v1702

ProMax® Training

BRE 101

Oil & Gas

Bryan Research & Engineering, Inc. Chemical Engineering Consultants

P.O. Box 4747 Bryan, Texas 77805 Office: 979-776-5220 Fax: 979-776-4818

sales@bre.com or support@bre.com

© 2016 BRE Group, Ltd.

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BRE Group, Ltd

Copyright 2016

TABLE OF CONTENTS

1 ProMax Oil & Gas Foundations .................................................................................................................................... 1

1.1. Course Description .......................................................................................................................................... 1

1.2. Course Agenda & Exercises ............................................................................................................................. 2

2 ProMax User Interface ................................................................................................................................................. 3

2.1. Overview ......................................................................................................................................................... 3

2.2. Visio Menus ..................................................................................................................................................... 3

2.3. ProMax Ribbon Menu ..................................................................................................................................... 4

2.4. ProMax Shapes ............................................................................................................................................... 5

2.5. Project Viewer ................................................................................................................................................. 5

2.6. ProMax Message Log ...................................................................................................................................... 6

3 Creating A Process Model ............................................................................................................................................ 7

3.1. Defining Environments.................................................................................................................................... 7

3.2. Drawing the Flowsheet ................................................................................................................................... 8

3.3. Defining Streams/Blocks ................................................................................................................................. 9

3.4. Unit Conversions in ProMax .......................................................................................................................... 20

3.5. Defining an Oil ............................................................................................................................................... 21

3.6. Creating New Flowsheets ............................................................................................................................. 23

3.7. Available Analyses in ProMax ....................................................................................................................... 24

3.8. Ideal Stage and Mass+Heat Transfer Column Types ..................................................................................... 25

3.9. Export / Append Project ............................................................................................................................... 26

3.10. ProMax Reports .......................................................................................................................................... 26

3.11. Gibbs Minimization Reactors in ProMax ..................................................................................................... 27

3.12. Utilizing Short Monikers and the Moniker Clipboard ................................................................................. 28

4 Optimizing A Model ................................................................................................................................................... 29

4.1. Overview ....................................................................................................................................................... 29

4.2. Excel Interactions .......................................................................................................................................... 29

4.3. Using Calculators in ProMax ......................................................................................................................... 31

4.4. User Defined Variables.................................................................................................................................. 33

5 Equipment Sizing & Rating Overview ......................................................................................................................... 34

5.1. Overview ....................................................................................................................................................... 34

5.2. Separator sizing ............................................................................................................................................. 34

5.3. Column Sizing ................................................................................................................................................ 35

5.4. Depressurization and Relief Valve Sizing ...................................................................................................... 36

5.5. Control Valves ............................................................................................................................................... 36

5.6. Heat Exchanger Rating .................................................................................................................................. 37

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6 Course Exercises ......................................................................................................................................................... 38

Exercise 1: Simple Gas Plant ................................................................................................................................. 38

Exercise 2: Pipeline Simulation ............................................................................................................................. 41

Exercise 3: Simple MDEA Sweetening Unit .......................................................................................................... 42

Exercise 4: Export/Append Project ....................................................................................................................... 45

Exercise 5: Glycol Dehydration Unit ..................................................................................................................... 47

Exercise 6: Simple Turboexpander Demethanizer ............................................................................................... 50

Exercise 7: Excel Import/Export ........................................................................................................................... 52

Exercise 8: Three Bed Claus Unit .......................................................................................................................... 54

Exercise 9: Scenario Tool ...................................................................................................................................... 57

Exercise 10: Simple Specifiers .............................................................................................................................. 60

Exercise 11: Simple Solvers .................................................................................................................................. 61

Exercise 12: User Value Sets ................................................................................................................................. 63

Exercise 13: Incinerator ........................................................................................................................................ 64

Exercise 14: Separator Sizing ................................................................................................................................ 65

Exercise 15: Depressurization............................................................................................................................... 66

Exercise 16: Shell & Tube Heat Exchanger Rating ................................................................................................ 67

7 ProMax Additional Exercises ...................................................................................................................................... 69

Exercise 17: Refrigeration Loop ............................................................................................................................ 69

Exercise 18: Ethylene Glycol Injection .................................................................................................................. 69

Exercise 19: Mixed Amines ................................................................................................................................... 70

Exercise 20: Activated MDEA for Acid Gas Removal ............................................................................................ 70

Exercise 21: Physical Solvent Acid Gas Removal .................................................................................................. 71

Exercise 22: Mercaptan Removal from LPG using NaOH ..................................................................................... 71

Exercise 23: CO2 Removal using NaOH ................................................................................................................. 72

Exercise 24: MEA Flue Gas CO2 Capture ............................................................................................................... 72

Exercise 25: Fractionation Train ........................................................................................................................... 73

Exercise 26: Environmental BTEX Calculations ..................................................................................................... 74

Exercise 27: Simple Sour Water Stripper .............................................................................................................. 75

Exercise 28: Air Cooler Rating............................................................................................................................... 76

8 Additional Help & Troubleshooting ............................................................................................................................ 78

8.1. Basic Specifications for ProMax Blocks ......................................................................................................... 78

8.2. General Guidelines for Diagnosing Errors ..................................................................................................... 79

8.3. Common Errors & Warnings ......................................................................................................................... 80

8.4. Web Tutorials ................................................................................................................................................ 84

8.5. Visio Hotkeys ................................................................................................................................................. 85

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ProMax Oil & Gas Foundations 1.1. COURSE DESCRIPTION

ProMax is a flexible, stream-based process simulation package used for the design and optimization of gas processing, refining, and chemical facilities. ProMax provides flexibility to its users through access to over 65 predefined thermodynamic package combinations and over 3200 components, along with crude oil characterization and compound species capabilities. For unit operations, the user has access to pipelines, fluid drivers (compressors and pumps), heat exchangers, vessels, distillation columns, reactors, membranes, and valves.

In addition, ProMax provides OLE automation tie-ins, specifiers, solvers, and Microsoft Excel® spreadsheet embedding, which give the user full access and control of all the information within any stream or block.

The exercises in this course are designed to show the basic functionality of ProMax. This includes the basics of how to draw flowsheets, create Environments, specify processes, and then display information from a completed project. This course also demonstrates many ProMax features for automization and optimization, such as how to set up Simple Specifiers and Solvers and how to utilize the Scenario Tool™. PSV and separator sizing, along with heat exchanger rating, are also discussed. These topics are discussed using applicable oil and gas processing focused exercises.

The general purpose of processing natural gas is to convert a raw gas that leaves the well into saleable products. This process can be separated into 3 main areas: collection and pre-processing, gas treating, and gas processing. ProMax can be used to model most of the systems used in these three areas. The figure on the right shows a general gas processing flow diagram; however, the processing steps might vary depending on the raw gas composition and requirements. In addition, field processing, such as dehydration and sweetening, may be required before the gas can be sent to the processing facility. Many of these systems are discussed and analyzed within the exercises of this course.

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1.2. COURSE AGENDA & EXERCISES

DAY 1 Exercise 1: Simple Gas Plant

Exercise 2: Pipeline Simulation

Exercise 3: Simple MDEA Sweetening Unit

Exercise 4: Export/Append Project

DAY 2 Exercise 5: Glycol Dehydration Unit

Exercise 6: Simple Turboexpander Demethanizer

Exercise 7: Excel Import/Export

Exercise 8: Sulfur Recovery Unit

Exercise 9: Scenario Tool

Exercise 10: Simple Specifiers

DAY 3 Exercise 11: Simple Solvers

Exercise 12: User Value Sets

Exercise 13: Incinerator

Exercise 14: Separator Sizing

Exercise 15: Depressurization

Exercise 16: Shell & Tube Heat Exchanger Rating

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ProMax User Interface 2.1. OVERVIEW

The ProMax interface is built around the Microsoft Visio® package. Therefore, it inherits many of the benefits of this package (e.g., shape sizing, transformation, text annotations, etc.). Starting ProMax will automatically start Visio with all of the ProMax interface included.

2.2. VISIO MENUS

Visio Ribbon Menu options are fully available within the ProMax project by selecting the “Home”, “Insert”, “Design”, “Review”, “View” or any additional Ribbon Menu options available. Ribbon Menu options can be adjusted through the Visio Options dialog from the “File” menu.

Some useful options within the Visio Ribbon Menus include shape alignment, pointer tool options, drawing page size, background borders or titles, image or text box insertion, and layer assignments.

Visual Basic for Applications can be accessed within the Developer Menu. It may also be accessed by pressing Alt-F11 if the Developer Menu is currently hidden.

ProMax Shapes contains all blocks, streams, and other shapes used in building the simulation.

Multiple flowsheets can be created within the same project.

ProMax Message Log displays the status, warnings, errors, and other information when the simulation is run.

ProMax Ribbon Bar provides quick access to all ProMax functionalities and options.

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2.3. PROMAX RIBBON MENU

General

Project Viewer – Opens the ProMax Project Viewer, which contains all project information. More details on the Project Viewer can be found on page 5.

Active Environment – Displays and manages the Environment in use on the current flowsheet. A drop-down menu provides access to all available thermodynamic Environments in the project.

Active Flowsheet – Displays information about what Environment is assigned to the active flowsheet. A drop-down menu provides access to manage all available flowsheets within the current project.

Oil – Displays and manages all defined oils in the project, including Single Oils, Curve Oils, and blends.

Warnings – Displays all warnings currently found within the project.

Report – Opens the report window to publish the results for the project into a document or worksheet.

Add Excel Workbook – Embeds an Excel workbook to the current project. Once a workbook is added, data can be exchanged between ProMax and Excel. Information on embedding an Excel workbook can be found on page 29.

Message Log – Displays information during execution such as block status, current solver error, column iterations, warnings, and errors.

Moniker Builder – Provides a method of creating “Short Monikers” for use within the project. Information on “Short Monikers” can be found on page 28.

Execute

Execute Project – “Runs” the complete project, including all flowsheets and calculators.

Execute Flowsheet – “Runs” the current, displayed flowsheet only.

Execute Block – “Runs” any selected block(s).

Abort – Stops the execution.

Clear Calculations – Clears any stored calculated data. User inputs, column solutions, and recycle streams are not updated, reset, or cleared.

Pause – Temporarily stops the execution.

Continue – Resumes a paused execution.

Options

Unit Conversion Drop-down – Allows on-the-fly unit conversions for the entire project. No user inputs or calculated data are changed.

Project Options – The icon displayed next to the word “Options” opens the dialog to customize atmospheric pressure, reference temperature, displayed properties, and other items

Help

ProMax Help – Provides parameter definitions, simulation setup help, common operating conditions, etc.

About ProMax – Displays the current version and build number of ProMax, as well as contact information, and some licensing and security device information.

Scripting Help – Reference documentation for JScript and VBScript.

Contact Support – Opens the BR&E Support website.

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2.4. PROMAX SHAPES

ProMax Shapes are a collection of blocks, streams, and other items used in building the flowsheet. Shape functions in ProMax can be thought of as including:

1. Unit operations – heat exchangers, pumps, columns, etc…

2. Streams – process and energy

3. Simulation specific blocks – recycles, make-ups, etc…

4. Data presentation blocks – callouts and tables

Only ProMax Shapes are loaded when ProMax starts. Other Visio shapes can be loaded, but will not interact with ProMax. This means that other Visio shapes can be drawn on the flowsheet for display purposes, but they will not act as ProMax objects with ProMax capabilities. Shape groups can be opened and closed as needed. To close a group, right click on the group title and choose Close. To open a group, go to More Shapes > then choose the desired group to open.

2.5. PROJECT VIEWER

The Project Viewer is the primary graphical interface to input and retrieve information within ProMax. The Viewer provides access to the majority of the information in a project, and provides additional shortcuts to running ProMax.

Contents

File / ProMax / Window Dropdown Menus – Contains options for the ProMax Project specific to the Project Viewer, including the option to open additional Project Viewer windows for simultaneous viewing.

Toolbar – Provides easy access to common ProMax operations (e.g., Environment, Execute, Report) and navigational buttons.

Navigation Tree – Includes a detailed list of all Flowsheets, Process and Energy Streams, Blocks, Calculators, and other objects contained in the Project. All of the various objects can be accessed by double-clicking directly in the navigation tree.

Upstream/Downstream Arrows – Provides a convenient method to navigate successive streams and blocks.

Data Display – The information displayed here depends on the selection. If a process stream is selected, the Viewer will have a “Properties” tab showing the stream properties, a “Composition” tab showing the composition of that stream, an “Analysis” tab, showing any analyses requested for that stream, and a “Notes” tab for user-added notes. An energy stream will have only a “Specifications” tab for the energy rate and a “Notes” tab. Similarly, a different set of information is displayed for the different blocks.

Message Log – Similar to the ProMax Message Log but displays messages related to the selected item only.

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Color Convention

The data displayed in the Project Viewer cells are color-coded for easy identification as follows:

Project Viewer Cell "Convention" Explanation

White Cell Background with No Text Available parameter, can be user-specified

White Cell Background with Blue Text

User-specified parameter

White Cell Background with Black Text Calculated or default parameter, can be overwritten

Gray Cell Background

Calculated parameter, unavailable for specification

Blue Cell Background

Value from a solver, specifier, or import from Excel

Red Cell Background

Parameter not applicable, calculation failed

Yellow Cell Background

Parameter value extrapolated or approximated

2.6. PROMAX MESSAGE LOG

The ProMax Message Log provides a running source of information about the status of a project and whether the execution is proceeding as desired. This provides an opportunity to see if any column solutions are approaching a solution, the ability to see if a recycle or solver is converging, and the chance to follow many additional aspects of a project during execution.

Additionally, any warnings are presented in blue, and failures are shown in red. The text provides the object in the project that is failing (e.g. ProMax:ProMax!Project!Flowsheets!Gas Processing!Blocks!VLVE-100 indicates the object “VLVE-100” on the “Gas Processing” flowsheet) and in many circumstances alerts the user to why the failure occurred.

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Creating A Process Model

ProMax provides freedom and flexibility when building a simulation. A simulation is started by defining the Environment and adding components or by drawing the flowsheet. During this process, changes can be made on any item as required.

When a new project is created, ProMax will create a flowsheet (Flowsheet 1) and assign an empty Environment (Environment 1) to that flowsheet. Flowsheets and Environments can be added, deleted, or modified at any point.

3.1. DEFINING ENVIRONMENTS

In ProMax, the term Environment is used to refer to the thermodynamic package, components, reaction sets, and oils specific to the simulation. The Environment dialog provides access to these properties. Multiple flowsheets can utilize the same Environment, or each may be unique.

To define an Environment, choose the “Edit Environments…” item from the drop-down options on the ProMax Ribbon Menu. This will open a window containing all project Environments. The dialog allows the user to create a new Environment, duplicate an existing Environment, or edit an existing Environment.

The Environment dialog has several tabs. The most commonly used tabs are the “Property Package” and “Components” tabs. The Property Package tab provides a list of thermodynamic equations that can be selected directly for use on a flowsheet. Alternatively, the user can modify options by selecting the “Use Custom Package” option. In this case, the user has the freedom to assign the desired thermodynamic model for each physical property.

Once a Property Package is set, components can be added to the Environment under the Components tab. Components may be added to the Environment by either manually searching in the components list or by using any of the filtering options provided. For example, to add methane to the components list, type “methane” in the Name filtering box and hit the “Enter” key. Many components have multiple aliases to choose from (e.g. CH4, C1, carbane, and r-50 are different aliases available for methane).

Choosing the correct Property Package is critical in obtaining reliable results. The table on the next page gives general guidelines on which packages apply to which applications. Refer to the ProMax Help for more information.

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Process Property Package Suggestion

Acid Gas Injection Systems SRK or Peng-Robinson

Air Separation SRK or Peng-Robinson

Amine Sweetening Amine Sweetening / Electrolytic ELR

Ammonia Absorption Refrigeration Tillner-Roth and Friend NH3 + H2O

Caustic Treating Caustic Treating

Chemicals (e.g. separation of Acetone/Acetic Acid/Acetic Anhydride)

Any non-Electrolytic Gibbs Excess/Activity Coefficient (e.g. DUNIFAC, TK Wilson, UNIQUAC, etc.)

Crude Oil Distillation/Fractionation SRK or Peng-Robinson

Dehydration/Hydrocarbon Removal Using MeOH SRK Polar or Peng-Robinson Polar

Fractionation SRK or Peng-Robinson

Gas Processing with MeOH SRK Polar or Peng-Robinson Polar

Glycol Dehydration SRK or Peng-Robinson

HC Dew Point Control w/ DEPG SRK or Peng-Robinson

Heavy Hydrocarbon Systems PR, SRK, Braun K10, Chao-Seader, Grayson-Streed

(SRK or PR must be used if aqueous phase present)

Hot Oil System Heat Transfer Fluid

Hydrocarbon - Water Separation SRK-Kabadi-Danner

Lean Oil Absorption SRK or Peng-Robinson

LNG Processes GERG-2008, SRK, Peng-Robinson

Methanol-Water Distillation (Binary System) NRTL

Natural Gas Processing SRK, Peng-Robinson, GERG-2008

Physical Solvent Acid Gas Removal w/ NMP or MeOH SRK Polar or Peng-Robinson Polar

Physical Solvent Acid Gas Removal w/ DEPG or PC SRK or Peng-Robinson

Refrigerant Systems (e.g. R13/R22, Propane, etc.) SRK or Peng-Robinson

Sour Water Stripping Amine Sweetening / Electrolytic ELR

Steam Systems NBS Steam Tables

Sulfur Recovery Sulfur or Sulfur ASRL

3.2. DRAWING THE FLOWSHEET

To draw the flowsheet, click and drag any shape from the Shapes Stencils and drop it on the page at the desired location. Shapes can be connected with process or energy streams at the Connection Points. Connection Points in the shape are indicated by a small “x” as shown in the figure. These can either be process connections or energy connections, which are not interchangeable. The number and type of connections for each shape can be viewed in the Project Viewer.

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Once a block or stream is present on the flowsheet, it can be manipulated using standard Visio techniques. After a block or stream is created, its process parameters can be defined within the Project Viewer by double clicking on the desired block or stream.

Visio 2010: Connected inlet stream, unconnected outlet stream.

In Visio 2010, solid red indicates a connected stream outlet and a red outline indicates a connected stream inlet. Solid blue indicates an unconnected stream outlet, and a blue outline indicates an unconnected stream inlet.

Visio 2016: Connected inlet stream, unconnected outlet stream

This convention is changed in Visio 2013 and 2016. A green circle indicates a connected stream outlet, and a circle with a green dot indicates a connected inlet. A light gray square indicates an unconnected outlet, and a white square indicates an unconnected inlet.

Tip

The Visio Connector Tool provides a convenient way to draw several streams quickly. This option can be found from the Visio “Home” Ribbon. The user should switch back to the Pointer Tool when not drawing streams.

3.3. DEFINING STREAMS/BLOCKS

To run any part of the simulation, all the information needed by ProMax to perform the required calculations must be provided. The information is entered as parameters for process streams, energy streams, or blocks. Keep in mind that the properties of the streams and blocks are interrelated, which gives the option to either specify the property of a stream directly or to specify how the block affects the process stream. For example, the temperature at the outlet of a heat exchanger may be placed in the outlet stream or calculated from a change in temperature from the inlet stream.

ProMax uses color coding for streams and blocks to help the user along the way. The following table summarizes the color conventions used within the flowsheet:

Color Block Status Stream Status Comments

RED Unconnected Not ready Stream: specification(s) missing

Block: stream connection(s) missing

BLUE Unsolved N/A Block has the minimum number of connections required

BROWN N/A Unsolved Stream is fully specified and ready for execution

ORANGE Approximate Approximate Properties inside a stream or block may also be orange, which generally indicates a calculation outside the correlation range

GREEN Solved Solved

ProMax allows for specifications to be made both upstream and downstream of most blocks, giving the user flexibility to specify properties in the most convenient fashion. The guide below lists provides a list of all available ProMax shapes along with specification recommendations.

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Auxiliary Objects

Divider – This block can be used to split any percentage of any specific components from the main process

stream. This is often useful in cases where a full simulation is unnecessary, such as a dehydration unit that does not need a rigorous simulation. There must be one inlet and at least one outlet, although typically two are used. An energy stream should also be connected to keep the simulation in both heat and material balance. The desired component splits must be set within the block itself.

Pipeline – The pipeline block can rigorously solve for many properties of single- or multi-phase flow in a pipe of any alignment. Ambient losses can be calculated based on pipe and ground material if an energy stream is connected to the pipeline block. Multiple pipe and fitting segments can be modeled in a single pipeline block.

Saturator – This block can saturate a stream with any component to whatever saturation level is desired. The temperature and pressure of the stream being saturated remain unchanged. Generally, multi-phase streams should be separated before feeding a single phase to the saturator block. Please see the Help for additional information.

Make-up/Blow-down – If there are losses in a process, material must be made up to keep a steady circulation rate. The make-up/blow-down block allows the user to set a desired flow rate to be maintained (set in the outlet stream). The block will calculate how much to add to maintain this flow rate on an ongoing basis. When applicable, this block also allows the user to set a desired outlet concentration (such as what weight percent the amine should be at leaving the make-up/blow down block).

AutoKinetic Reactors

ProMax can perform simulations for a variety of catalytic processes including Isomerization, Catalytic Reforming, Hydrodesulfurization, Hydrocracking, Hydrodewaxing, Hydroisomerization, Hydroskimming and Hydrofinishing for a range of oil fractions spanning from light naphthas to heavy vacuum gas oils.

Oil Speciation – This block estimates the composition of a mixture of species that represents the bulk properties of a given oil sample. The user defines the species list to be used and the block estimates a composition to fit the specified oil assay.

Kinetics Calibrator – This tool provides an easy-to-use graphical interface to calibrate kinetic parameters from plant data.

TBP Splitter – The TBP Splitter provides a quick, perfect separation of an inlet stream into as many as 10 cuts based on TBP spreads. This represents the maximum quantities of each cut that could be produced.

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Cut Point – A block for determining the performance of a fractionation unit. The block estimates the Cut Point Temperature and the degree of cross contamination between the two streams connected to it.

Catalytic Fixed Bed – A block for modeling a complete fixed particle bed reactor vessel.

Top Bed – A block for modeling a fixed particle bed located at the top section of a reactor vessel.

Bed Section – A block for modeling a fixed particle bed located in a middle section of a reactor vessel.

Bottom Bed – A block for modeling a fixed particle bed located at the bottom section of a reactor vessel.

Distillation Columns

There are predefined distillation columns available from the stencil set that can be used for most common applications. More complex arrangements may be setup by manually drawing the desired configuration.

ProMax provides two fundamental methods of calculating the column results: Ideal Stage and Mass + Heat Transfer. Ideal stage modeling can be used for any application to simulate VLE, LLE, and VLLE columns. Ideal stage models use tray efficiencies or HETP values to model trayed and packed columns using ideal stages. Column internals are generally not required for Ideal Stage modelling, although they are required for amine absorbers as described in the following paragraph.

Most Ideal Stage model applications will use the “General Ideal Stage” Column Type, with exceptions for amine sweetening. Amine absorbers will use the “TSWEET Kinetics” model, and amine regenerators will use the “TSWEET Stripper” model. The “TSWEET Kinetics” model requires tray and column information to calculate the residence time on a tray to fully model the reaction kinetics. Typical initial design input values are 70% flooding, a Real/Ideal Stage Ratio of 3, a system factor of 0.8, tray spacing of 2 ft [0.6 m] and weir height of 3 in [7.6 cm]. These values are input in the Hardware grouping on the Stage Data tab of the absorber column. Please see the ProMax Help for additional information on tower hardware specifications.

Mass + Heat Transfer-based modeling can also be used for all VLE applications. Mass + Heat Transfer models use the actual number of trays in a column. Additionally, with the Mass + Heat Transfer model there is no need to assume an HETP for packing as the actual packing height may be entered. However, column internals are required for all Mass + Heat Transfer modelling. Mass + Heat Transfer models account for departures from equilibrium temperatures between the phases. Matching operating data may be easier with these models due to mass transfer correlation options.

For help with Mass + Heat Transfer column specification, please see the ProMax Help.

All columns must have a pressure profile set (i.e., pressure drop, or top and bottom pressure, etc…). In addition, each condenser, reboiler, draw or pump-around adds a degree of freedom. Each degree of freedom requires a specification, chosen from the following options.

By default, ProMax will solve to zero degrees of freedom. The “Allow over-specification” permits the selection of more specifications than can be solved exactly, and ProMax will solve to the closest solution it can find based on a least-squares methodology.

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Available Column Specifications Boiling Curve Gap – The difference between boiling curve temperatures at specified fractions for selected

stage(s) and phase(s). For example, the user can specify that the bottoms liquid from a distillation tower should have a 200°F (110°C) gap between the 10% and 90% boiling curve temperatures for an ASTM D86 test.

Boil-up Ratio – The flow of vapor returned to the column from the reboiler divided by the flow of bottom product (molar basis).

Component Flow/Composition – The flow rate or fraction of one or more of the available components in one of the streams exiting the distillation column.

Component Ratio – The ratio determined by specifying a numerator, the flow of one or more components; and a denominator, the flow of one or more other components.

Component Recovery – The ratio of the flow rate or fraction of one or more of the available components in one of the streams exiting the column to the flow rate of the same selection in the total feed to the column. o If a flow unit is chosen, this designates the fraction of the selected components from all feeds that will

be sent to the specified stream. o If a fractional unit is chosen, the value is a dimensionless ratio of the fraction of the components in the

specified stream to the fraction of the components from all feeds. For example, if the feed to a deethanizer contains 7.28 mol% ethane and the bottoms contains 14.45% ethane, then the ethane fraction recovery in the bottoms is 14.45/7.28 = 1.985.

Cut Point – The boiling temperature of the oil at a certain percentage distilled for the specified stage and phase. All distillation curves are calculated on a dry basis.

Draw Rate – The flow rate in one of the draw streams from the column.

Draw Recovery – The ratio of the flow rate of one of the streams exiting the distillation column to the flow rate of the total feed to the column.

Duty – The duty associated with an unspecified energy stream attached to the distillation column. The value should be positive for heat injected into the column (and the energy stream arrow points towards the column) and negative for heat removed from the column (and the energy stream arrow points away from the column).

Flow Ratio – The ratio of the flow in a draw stream or on a stage to the flow in another draw stream or on another stage.

Fraction Vapor – The percentage of vapor in the total distillate or bottoms product. This specification is intended to be used for a column with a partial condenser including a liquid draw from the reflux, or a reboiler with a vapor draw from the vapor return stream. The column automatically calculates the liquid draw rate for the condenser or vapor draw rate for the reboiler to meet the specified value. Note that this specification does NOT decrease the degrees of freedom for the column; instead it sets the percent split in the splitter involved.

Fuel Property – A fuel property for any phase on any stage. These properties are calculated on a dry basis, and include the following options:

Cetane Index

ASTM D93 Flash Point

ASTM D611 Aniline Point

Absolute Viscosity at 100F

Absolute Viscosity at 210F

API Gravity 60F/60F

Paraffinic Mole Percent

Naphthenic Mole Percent

Aromatic Mole Percent

Research Octane Number

ASTM D97 Pour Point

Refractive Index

Watson K

Kinematic Viscosity at 40C

C:H Weight Ration

ASTM D86 10% Cut Point

ASTM D86 50% Cut Point

ASTM D86 90% Cut Point

ASTM D1322 Smoke Point

ASTM D2500 Cloud Point

Phase Property – A phase property for any phase on any stage in the column. Select the desired property from the drop-down list which includes all standard properties available for a stream (e.g. Temperature or Flow Rate) along with the Reid Vapor Pressure and True Vapor Pressure.

Reflux Ratio – The flow of liquid from the condenser returned to the column divided by the flow of vapor and liquid overhead products.

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The following items are available through the specifications tab of the column but will not fulfill a degree of freedom. These items are used as either an initial estimate for iteration purposes, or to report back values for parameters of interest.

Lean Approach – The equilibrium composition of the selected component for the specified stage and phase divided by the calculated composition of the selected component for the same stage and phase. This specification is useful for determining "Lean End Pinch" for amine sweetening absorbers, and also for determining the approach to equilibrium water content in glycol dehydration contactors.

Pump-around Estimate – An estimate sometimes required for pumparound loops. Options are: a. Fraction Feed Entering Column – If the pump-around path contains a mixer followed by a splitter,

the fraction of added material that reaches the column should be given as the estimate. For example, 100 mol/h of material is added to a 900 mol/h pump-around via a mixer, and 50 total mol/h of material is subsequently removed from the pump-around via a splitter. The "Fraction Feed Entering Column" would be 95% since 95 mol/h of the 100 mol/h feed reach the column. (5 mol/h or 10% of the 50 mol/h removed via the splitter is attributable to the feed). If the splitter has a % split specified instead of an outlet flow rate, this estimate is not required.

b. Fraction Draw Returned – If any stream between the draw and the return contains a splitter, the fraction returned to the column should be given as an estimate. For example, if the pump-around draw is 1000 mol/h and 150 mol/h is removed from the pump-around via a splitter, then the "Fraction Draw Returned" is 85%. If the splitter has a % split specified instead of an outlet flow rate, this estimate is not required.

c. Pump-around Duty – If duty is added to a pump-around by a heat exchanger (other than a condenser or reboiler) or pump, an estimate may be required for the total pump-around duty amount (positive if energy is added to the system). If the duty itself is specified, this estimate is not required.

Rich Approach – The calculated concentration of a selected component in the liquid exiting a specified stage divided by the equilibrium concentration based on the specified lean feed. Select either: "Maximum Loading", which reports the rich approach as a percentage of the highest loading attainable (equilibrium), or "Excess Solvent", which reports the rich approach as the percentage solvent flow in excess of the flow required for max load. This specification is useful for determining "Rich End Pinch" for amine sweetening contactors.

Side Column Estimate – An estimate sometimes required for side columns. Estimate options are: a. Fraction Feed Entering Column - If either path between the main and side columns contains a mixer

followed by a splitter, the fraction of added material that reaches the column should be given as the estimate. For example, if 100 moles of material are added to the path from the main column to the side column via a mixer, and 40 moles of material are subsequently removed from the same path to the side column via a splitter, the "Fraction Feed Entering Column" would be 60%.

b. Fraction Draw Entering Column - If any stream between the main and side column contains a splitter, and there is not a mixer like was mentioned above, the fraction that is returned should be given as the estimate. For example, if the draw from the main column to the side column is 100 moles and 15 moles are removed from the path to the side column via a splitter, then the "Fraction Draw Entering Column" is 85%.

c. Side Column Duty – If duty is added to the path from the main column to the side column, or from the side column to the main column via a heat exchanger, the amount should be given as an estimate (positive if energy is added to the system).

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Fluid Drivers

All fluid drivers (blowers, compressors, expanders, and pumps) should have either an efficiency or performance curve designated. An outlet pressure or change in pressure should also be defined. Recommended practice is to set the pressure in the outlet stream, as doing so will maintain the set pressure even if the upstream pressure is changed.

Heat Exchangers

Pressure drops or outlet pressures must be supplied for each side of an exchanger. A pressure drop is more commonly specified and is generally recommended.

Having pressure drops set on each side of a single-sided or two-sided exchanger leaves 1 degree of freedom around the exchanger. This should be specified based on outlet stream temperatures, exchanger duty, UA, or approach temperatures. Exchangers with more than two sides will have more than 1 degree of freedom, with the degrees of freedom being equal to the number of sides minus 1.

Mixers/Splitters

Mixers may have an unlimited number of streams mix together into one outlet stream, while splitters may have as many outlet streams as needed from a single inlet. In splitters, the user may designate the percent splits within the block or the flow rates in the outlet streams. Each inlet connection point on a mixer can accept multiple inlet streams. Mixers and splitters have a default pressure drop of zero, but this may be changed if necessary. The outlet pressure of a mixer is equal to its lowest inlet stream pressure minus any pressure drop designated in the mixer.

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ProMax Property Stencil

The ProMax Property Stencil is designed to add customizable functionality to ProMax, giving an option to embed and share VBScript-based calculations. Many examples are available for use and modification. The Property Stencils may be found in the “More Shapes” menu.

Single Line Property – Displays any single piece of information from the project on the flowsheet.

Property Input – Displays any user-defined parameter from the project on the flowsheet. The value may be modified directly on the flowsheet by typing in the new value and pressing enter.

Property Connector – Connects to another property stencil, such as the “Property Calculator”, to allow the user to quickly change a variable within that other stencil. This essentially changes the value of the variable within the stencil to match whatever stream the other end of the “Property Connector” is attached to.

Property Calculator – Allows a user to write script calculations based on variables within ProMax. The results are displayed directly on the flowsheet. Any number of variables can be defined by double-clicking in the grid area and browsing through the tree diagram. Click on “Edit Script Function” to define what will be displayed on the flowsheet.

Stream’s Cn+ GPM – Displays the potential Cn+ from any single stream in standard gallons per MSCF (thousand standard cubic feet). The “n” may be modified by double-clicking on the shape, selecting “edit source” and then double-clicking on the “intMinCAtoms” value and replacing the number (5 is the default).

Sum I/O Property – Displays the sum of a selected property across all input streams, if an input stream is selected; sums the property across all outlet streams if an outlet stream is selected; or sums the property across all internal (non-outlet/inlet) streams if an internal stream is selected.

API Vapor Relief Area – Deprecated (Use stream “Relief Valve Sizing Analysis” instead)

API Steam Relief Area – Deprecated (Use stream “Relief Valve Sizing Analysis” instead)

Data Exchange – Allows bi-directional specifications between an embedded Excel workbook and ProMax. This feature is most useful when writing compositions from Excel into ProMax.

Solver/Specifier Example – A shell that supplies a value to a script based ProMax Calculator (solver or specifier) with appropriate VBScript edits. Allows the user to write solvers and specifiers with VBScript.

Cn+ GPM Solver – This stencil works identically to the [Cn+] solver on the following page except that the units solved for will be standard gallons per MSCF.

Cn+ Flow/Frac. – Displays the total flow rate or fraction of any single stream of all components containing the minimum carbon atoms. By default, it calculates the flow rate of C3+. It can report in molar, mass, normal vapor, standard liquid or vapor, or volumetric units.

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Flow Duplicator – Copies a reference stream’s composition and sets target stream flow rate. Pressure and temperature are not set, and must be designated by the user. The target stream MUST be connected to a block, even if it is a valve with 0 pressure drop. The flow rate will NOT update otherwise.

UA Wizard – Creates a solver on a selected variable to solve an exchanger to a user-specified UA, LMTD, Approach Temperature, or percent over design.

Elemental Flow Example – Displays the total flow of a given element in a selected process stream.

Copy Stream – Copies a reference stream by transferring molar enthalpy, pressure, component mol fractions, and molar flow rate. Target stream MUST be connected to a block, even if it is a valve with 0 pressure drop. The flow rate will NOT update otherwise.

[Cn+] Solver – Manipulates a selected variable to achieve a desired Cn+ fraction or flow rate in a selected target stream. A blank Simple Solver must be created on the manipulated variable prior to placing the stencil on the flowsheet. The connector on the shape should then be placed on the target stream. The desired fraction or flow rate should be defined by double-clicking on the shape and changing the value.

PipeLine Mach Number – Solves for a specified Mach number through the pipe. By default, it will change the flow rate of the fluid until the Mach number is 1. The user should set an inlet flow rate as an initial guess for the solver. A desired Mach value can be specified by double-clicking on the shape.

Flow Multiplier – Copies a reference stream’s molar enthalpy, pressure, and composition, then modifies the reference stream’s flow rate by a multiplier. Default = 2x. Target stream MUST be connected to a block, even if it is a valve with 0 pressure drop. The flow rate will NOT update otherwise.

Membrane – Solves for asynchronous vapor separation in a membrane. Permeability values and available membrane area is defined in the block.

Membrane Permeabilities Example – Displays component permeability values directly on the flowsheet.

Orifice Plate – This can simulate either an orifice plate or a nozzle/venturi. It is capable of solving outlet pressure, inlet pressure OR mass flow, depending on what is specified in the inlet and outlet streams. Double-click on the shape to specify parameters.

Salt Example – Double-click on the shape to specify the stream in which an aqueous salt is desired. Then, select the desired salt and the mass percent of the salt in the solution. The tool will then add the required acid and base to the Environment, calculate the required amount of each in the stream, and define the composition based on this.

Chart – Allows the user to generate simple plots such as the column temperature profile or the temperature at each increment through a heat exchanger. These plots can be generated using the Plots tab of these blocks, but the Chart version can be conveniently placed on the flowsheet.

Component GPM – Displays the standard gallons per MSCF of any single selected component.

Date Example – Displays the project name and the created, saved, modified, and solved dates and times. This can be modified by changing the solver scripts.

Phase Envelope – Displays the phase envelope of a selected stream on the flowsheet. The current stream conditions are shown on the diagram with a red “X”.

Heat Transfer – Displays the heat transfer chart of a selected exchanger on the flowsheet.

Sum Component Flow/Frac. – Displays the sum of flows or fractions of components selected by the user. Many pre-defined groups are available, such as BTEX and Greenhouse Gases, but any components in the selected stream may be summed by choosing User Defined in the drop-down list.

GWP Calculator – Displays the global warming potential of a selected stream in mass flow of equivalent CO2.

Emission Factor – Calculates the emissions factor for pollutants in lb/bbl for a user-specified vapor and liquid PStream. Pollutants include VOCs, Benzene, Toluene, Ethylbenzene, Xylenes, n-Hexane, and 2,2,4-Trimethylpentane.

Flammable Limit – Estimates the upper and lower flammability limits for a hydrocarbon mix in ambient air.

Reversipator – This reverse separator calculates the pressurized liquid and flash gas compositions and flow rates by supplying the temperature, pressure, flow rate, and composition of a condensate stream, and the temperature and pressure of the pressurized liquid stream. Assumes that the condensate and pressurized liquid streams are at their bubble point.

Oil/Water Emulsion – This will modify the properties of an existing Single Oil to create an emulsion, and save this new component into the current Environment. The water volume fraction is then specified by double-clicking on the shape.

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Depressurization Example – This tool estimates an orifice diameter required to depressurize a vessel to a given pressure in a given amount of time. The user should set the vessel volume, vent pipe diameter, vessel initial pressure and temperature, downstream pressure, target pressure, time to reach target pressure, etc.

Latent Heat Example – This example estimates the latent heat of a stream from one vapor fraction to another at constant pressure.

Heat of Vaporization – An alternative method of estimating the heat of vaporization of a stream.

P/H Diagram – Displays the Pressure/Enthalpy diagram of a selected stream on the flowsheet. The current stream conditions are shown on the diagram with a red “X”.

P/S Diagram – Displays the Pressure/Entropy diagram of a selected stream on the flowsheet. The current stream conditions are shown on the diagram with a red “X”.

Inline Flow Multiplier – Transfers a process stream’s conditions and composition from one connected stream to another. The flow specification is set from the source stream and multiplied by the Flow Multiplier parameter. The user has the ability to select which properties to transfer to the target stream.

HTRI Data Transfer – This shape is designed to facilitate direct data transfer from a ProMax heat transfer unit operation to an HTRI ® input file. A licensed copy of the HTRI software must be installed on the computer to use this tool. The data transferred from ProMax to HTRI includes inlet and outlet conditions for the heat transfer, along with the thermodynamic property data required by HTRI.

Calculator Callout – Displays calculator related information directly on the PFD.

Stream’s Component Ratio – Displays a stream's user-defined component ratio.

Tank Losses – Follows the AP-42 methodology for calculating the rate and composition of volatile losses from a liquid storage tank. Working losses, breathing losses, loading losses, and flashing losses are calculated for liquid storage tanks operating at or near atmospheric pressure, and are suitable to calculate the average annual or monthly loss rate for environmental reporting applications.

Eductor – Calculates eductor area ratio based on inlet conditions.

Shortcut Distillation – Estimate ideal stage requirement, feed location, and minimum reflux ratio given a process stream.

Liquid Dielectric Constant – Estimate the liquid dielectric constant for a process stream.

Block Calculator – Creates a new stencil that is based on an existing block from the flowsheet. The stencil saves user defined properties (e.g., temperature on an outlet stream) and specifiers or solvers associated with the block. The values can be changed from the dialog for each user defined property. A “Master Name” should be selected for the stencil name, and then “Store in Stencil” selected to save the shape. Once stencils have been saved, the “Save” button in the top right-hand corner of the stencil will save the stencil for future use. Both this saved stencil group and the ProMax property stencil set must be open to use these created stencils.

Shape Converter – Modifies any Visio object into a ProMax shape. Connection points can be added from the connection point tool (in the same group as the connector tool); block type and connection point assignments are made in the stencil. Once both the shape and stencil set are saved, the shape may be used in any project.

Shape Swap – Drag this shape out and drop it on a ProMax shape to switch it with another compatible ProMax block shape.

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Reactors

There are several options for reactors in ProMax, including Conversion, Equilibrium, Gibbs Minimization, Plug Flow, Plug Flow with Mass Transfer, Stirred Tank, and Stirred Tank with Mass Transfer. The reactors discussed in this training are generally designed for sulfur recovery units, so this section will focus on the Gibbs Minimization option. The other options require reaction sets to be defined and used; for more information on these reactors and reaction sets, please see the ProMax Help.

Within the Gibbs Minimization choice there are “Gibbs Sets” options which are explained below. Each step of the sulfur recovery process has a corresponding Gibbs Set, with many constraints and reactive species predefined.

General – This option can be used for any general reactor type for which the Gibbs Minimization option will be used. This does not include any constraints and all species are reactive.

Acid Gas Burner – This set includes constraints on COS and CS2 production during the burning of acid gases, and should be used when modeling a burner that has either H2S or CO2 in the feed. The NSERC correlations are valid for an 8%-98% (mol) H2S composition and 0.1%-5% (mol) CO2 composition.

Burner – This model has no constraints set by default, and all components are Gibbs Reactive (i.e. all components are included in the reaction). Can be used to model incinerators, Reducing Gas Generators (RGGs), or fuel gas burners.

Claus Bed – For all typical Claus beds, this choice is best. All species involved in the Claus reaction are reactive. Note: COS and CS2 are not reactive at typical conditions for the Claus reactors.

Equilibrium Hydrolyzing Claus Bed – As opposed to the “Claus Bed” option, the “Hydrolyzing Claus Bed” allows the COS and CS2 to react, as this bed is designed to be operated at higher temperatures and with a specialized catalyst to destroy these species.

GPSA Hydrolyzing Claus Bed – This option adds constraints to the destruction of COS and CS2 in concordance with the correlations from Section 22 of the GPSA Data Book.

Reaction Set Only – A reaction set should be created for this option, otherwise no reactions will occur. Gibbs Reactive components are selected to match the reaction set, and cannot be overridden.

Sub-Dewpoint Claus Bed – This choice best models those Claus beds that are operated where sulfur condenses directly on the catalyst and the bed undergoes a regeneration cycle.

Sulfur Condenser – The Sulfur Condenser allows further reactions for sulfur redistribution at the cooling temperatures, but no other reactions.

Sulfur Direct Oxidation – This selection is for sulfur recovery units that utilize direct oxidation methods typically used where the H2S concentration is too low for combustion, even with a split flow configuration.

Sulfur Hydrogenation – The hydrogenation option models the reactions of the tail gas with an oxidizing stream to recreate H2S as the stream is passed on to an amine tail-gas treating unit.

Sulfur Partial Oxidation – The "Sulfur Partial Oxidation" or SUPERCLAUS® type Reactor uses a special catalyst for "selective oxidation" that converts almost all of the H2S directly to sulfur and is usually the final bed in a Claus unit. In ProMax, Sulfur Direct Oxidation mainly converts H2S to SO2, whereas Sulfur Partial Oxidation converts the H2S to elemental sulfur.

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Sulfur Redistribution – This option is used to represent the second pass of the waste-heat boiler in a typical Claus burner-WHB setup. The only reactions allowed in this Gibbs set are for the redistribution of the sulfur species; no other species are allowed to react. This can also be used to model reheaters more accurately.

Sulfur Thermal Reaction Zone – This is used to model the first pass of the waste-heat boiler. Constraints are added to a few components that cease reacting once the temperature has cooled below a set temperature.

Recycles

Process Recycle – This block is used when any downstream material is recycled back into the process

upstream. Analyzing the flowsheet to reduce the number of recycles necessary by combining as many as possible is typically encouraged, as this will reduce the execution time.

o The stream exiting the recycle block must be fully user-defined, including temperature, pressure, composition, and flow rate. This guess provides ProMax a place to begin its execution, and is overwritten each time the recycle iterates. This block is considered “solved” when the stream entering the recycle block is the same, within tolerances, as the stream exiting.

o Priorities must be set for recycle blocks. All default to a priority of 1, but should be adjusted to match the necessary solve order. Priorities may be set as any integer number with higher priority numbers solved first.

Q-Recycle – This block is used when energy is taken from somewhere downstream and applied to an upstream location. Often this occurs with a glycol reflux coil, as the amount of cooling that occurs in the coil is generally dependent upon the specification of the distillation column, and the outlet temperature of the rich glycol is not directly controlled, even though it is upstream of the column. This case is demonstrated in Exercise 5:“Glycol Dehydration Unit”.

o The initial guess for a Q-Recycle is provided in the block itself, unlike with the Process Recycle. This guess is provided as the “Calculated Value” on the Process Data tab. Priority, zero by default, should be adjusted to match the necessary solve order. Higher priority numbers solve first. Bounds and step size are optional, and typically not recommended.

Propagation Terminal – The propagation terminal is a specialized recycle block designed to be used in closed-loop systems where no material enters or leaves the loop, such as is found in refrigeration loops, hot oil loops and similar systems.

o The terminal allows chosen properties to propagate through the block, unlike a recycle block that will break all propagation. Two properties should be selected, typically pressure and temperature, but this depends on how the loop is specified. Please read the ProMax Help or review the ProMax example files for more information on how to use a propagation terminal.

Separators

Two Phase Separator – This block allows the separation of liquid and vapor phases of a process stream. There

may be multiple inlet streams attached to the separator but only two outlets: one vapor and one liquid. A pressure drop or outlet pressure must be specified. Energy streams may also be attached. If this is done, an additional degree of freedom is given, and should be specified as an outlet temperature or fraction vapor in the separator.

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Three Phase Separator – This block is similar to the two-phase separator, except that the three-phase separator allows separation of vapor, light-liquid, and heavy-liquid phases. On the Process Data tab, there is an option for the “Main Liquid Phase”. This allows the user to specify whether the liquid phase should use the light- or heavy-liquid outlet if there is only one liquid phase predicted by ProMax.

Entrainment – This property may be set within a separator for any phase into any other phase, on a variety of bases. The values are user-defined.

Streams

Process Stream – ProMax is a stream-based simulator; therefore, process streams typically contain most of

the specifications. For a stream to be fully specified, two “flash variables” (these include temperature, pressure, mole fraction vapor, and enthalpy), a flow rate, and a composition should be known or propagated from upstream or downstream.

Energy Stream – These are dotted streams representing the energy input or removed from blocks such as compressors, pumps, some heat exchangers and separators, etc.

Cross Flowsheet Connector – These allow stream information to cross from one flowsheet to another. If a process stream is connected, then pressure, enthalpy, and molar fractions are transferred. Since Property Packages may change between flowsheets, warnings can be set for any variation in these values from one flow sheet to another. The user also has the ability to choose not to transfer components that are below a specified mole fraction in the stream. This gives the ability to limit the number of components in the new Environment to decrease the execution time.

Valves

JT Valve – The valve has several icons available, but all are identical in their operation. Typically, a pressure

drop across the valve or an outlet pressure is specified. In some rare cases, an outlet temperature or fraction vapor may be specified. Valves may additionally be utilized to model a control valve or differential flow meter, allowing ProMax to estimate the pressure drop for the block based upon correlations for these operations.

3.4. UNIT CONVERSIONS IN PROMAX

A drop-down list of various unit sets is available from the ProMax Ribbon Bar or the ProMax Project Viewer. This selection will update the default units displayed for all streams and properties in the current project.

If a single property is to be displayed in a different unit, most properties have a drop-down menu available where the current unit assignment is displayed. Selecting in this cell will provide new unit options as demonstrated below.

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If a particular unit is not available in the dropdown menu, it can be typed directly into the unit box. The ProMax Help lists acceptable abbreviations for all units available in ProMax.

ProMax will automatically convert any value if the assigned units are changed. Thus, the user should set the correct units before manually entering a value for an individual property. Alternatively, the user can type a value followed directly with its desired units when specifying a property value.

3.5. DEFINING AN OIL

ProMax has two oil classifications: Single Oil and Curve Oil. These can be created from the “Oil” option on the ProMax Ribbon. A description for creating the oils can be found below. A Single Oil is treated as a single component and can be used to model a single hypothetical component, such as a C6+ fraction. A Curve Oil is treated as a collection of several “cuts” and is used to model a crude oil with a large boiling range, typically defined by a TBP curve or D86 curve. Unlike a Single Oil, a Curve Oil may be fractionated in a distillation column.

After creating an oil, it must be added to the desired Environment(s) from the Environment dialog, under the components tab.

Single Oil

To define a Single Oil, one of the following combinations must be provided at a minimum:

Volume Average Boiling Point

Molecular Weight AND Specific Gravity

Molecular Weight AND API Gravity

All other information can be estimated by ProMax using common correlations. These correlated values may be overwritten; every additional piece of information provided by the user will improve the prediction accuracy as the correlations are updated.

Once added to the Environment, the Single Oil is found in the component list as a single component, with the properties that were previously specified.

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Curve Oil

To define a Curve Oil, a boiling point curve must be provided to ProMax. This curve can be on several bases, with the most common being D86 and TBP curves. If it is available, the TBP curve is preferable because ProMax will first convert other curves into an estimated TBP curve before creating the oil.

Independent curve data for Specific Gravity, Molecular Weight, and High and Low Temperature Viscosity may also be provided to better define the oil, if available.

Once the curve data is entered, ProMax will calculate additional properties of the oil. If any of these bulk properties, such as the API gravity or molecular weight, are known the ProMax’s predictions can be overwritten.

The second tab, “Cut Points”, provides a preview and allows modification to how ProMax plans to cut this oil into individual components. The number of cuts ProMax should take between given temperature ranges may be specified.

The predicted properties of each cut point are given in the table on the Cut Points tab.

The “Light Ends” tab allows the user to designate whether there are any light ends involved with this Curve Oil. These components, typically hexanes, heptanes, and other known hydrocarbons in the oil, will have better properties and interactions if ProMax can use the pure components instead of estimates from a Curve Oil. The options are:

Light Ends Free – This sets no light ends in the oil.

Light Ends Generated – ProMax will generate an estimate of the amount of each light end that is in the oil. The user must designate which components are present.

Light Ends Supplied – The user must provide information on which components are present and how much of each component is in the oil.

The “Correlations” tab provides information on all of the correlations ProMax is using for each property of the oil. Many of these correlations have alternatives that can be selected for more accurate predictions if the default predictions are not close enough.

The “Plots” tab provides several charts of the physical properties of the oil as a visual aid. These should be used to verify that the expected results are achieved.

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Speciated Oil

The most advanced oil characterization method available in ProMax is through the Oil Speciation tool. This tool provides a composition of a mixture of species that represents the bulk properties of a given oil sample, and provides a complex mixture from assay data. Look for more in-depth information in the ProMax Help, or at an advanced training course.

3.6. CREATING NEW FLOWSHEETS

ProMax allows the user to have as many flowsheets in a project as desired. Each flowsheet may have a separate Environment to allow multiple processes to be modeled in the same project. Additional flowsheets can be added using the ProMax “Flowsheets” menu option.

Alternatively, the user may right-click on the flowsheet tabs area below the flowsheet and “Add Flowsheet…”.

Note: The symbol and “Insert” options will insert a Visio page, not a ProMax flowsheet. These can be useful for certain types of drawings, but are not capable of executing ProMax calculations. ProMax objects drawn on a Visio page will display in black and white.

When creating a new flowsheet, the assigned Environment can be an existing Environment, a duplicate (copy) of an existing Environment that can then be modified, or a new Environment to be fully defined.

Once the flowsheet is created, a cross-flowsheet connector may be used to have a process or energy stream flow from one flowsheet to another. This block will appear on both of the two connected flowsheets as an arrow shape to indicate the process or energy flow direction. The process or energy flow directions must agree on both sides of the connector (e.g. an input on one sheet must be an output on the other).

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3.7. AVAILABLE ANALYSES IN PROMAX

Analyses can be added to any stream in ProMax by clicking on the “Analyses” tab from the Project Viewer, and selecting “Add Analysis…” towards the bottom of the screen. The options are:

Amine Analysis – Presents information on carbon dioxide, hydrogen sulfide, and total acid gas loading in an amine stream. It also shows the pH and Molarity of the stream.

Combustion Analysis – Determines the required combustion oxygen for a stream, as well as various heating values, the Wobbe Index, Motor Octane Number, Methane Number, and Heat Release value.

Composition Subset – Calculates properties and flow rates on selected component “groups” within a stream, e.g. “C3+ Hydrocarbons”, “BTEX”, “Kerosene”, “Sulfur Components”, etc. User-defined grouping is also available.

Control Valve – Estimates many properties of a selected control valve for use in a process stream. Tables and plots of the valve Cv, choked pressure drops, and choked mass flow may also be produced.

Differential Pressure Flow Meter – Calculates the pressure drop, flow resistance, flow coefficient, and other properties for orifice, nozzle, and venturi flow meters. Other flow meter types may be modeled by specifying the permanent pressure drop ratio and discharge coefficient. A resistance coefficient calculated from the analysis may also be used as an input for a fitting segment in a pipeline.

Distillation Curves – Presents a table and plot of a distillation curve based on TBP, ASTM D86, ASTM D1160, ASTM D2887/SD, or EFV on either a wet or dry basis of the selected stream.

Freeze Out, Hydrate, H2O Dew Point – Determines the solids formation temperature, water content, and water dew point for any stream phase, including multiple hydrate points, structures and regions. This last point may be useful if operating below the highest hydrate point, but not in the hydrate region.

Fuel Properties – Predicts fuel properties of the stream, including the Flash Point, high- and low- temperature viscosity, API gravity, various ASTM cut points, and the smoke or cloud point.

Ionic Information – Presents information on the ions present in the stream if an electrolytic Environment is being used, including ionic and salt compositions, and pH values.

Line Sizing – Calculates the required nominal pipe size based on a limited gas velocity, pressure drop, or both. Inputs can include the inclination angle, pipe schedule, pipe roughness, material of construction, corrosion allowance, and other variables.

Phase Envelope – Generates a plot and table from a stream on either a wet or dry basis. By default, a bubble/dew point curve is created, but this can be modified. ProMax automatically matches the bubble-point curve if the dew-point curve is requested, and similarly will match the 90% curve with the 10% curve, etc… A Hydrate Curve, Dry Ice Curve, or Ice Curve can also be included.

Relief Valve Sizing – Estimates a relief valve size by following a chosen standard, with the default being the ASME API RP520. Relief Temperature and Pressure, Set Pressure, Over Pressure, Back Pressure, Flow Rates, Coefficients, and Corrections are all available for specification. The stream Latent Heat can also be found on this analysis as defined by the standard.

Vapor Pressure, Dew, Bubble Point – Calculates Bubble and Dew Point pressures and temperatures on a wet or dry basis. The True Vapor Pressure (TVP) at 100°F and the Reid Vapor Pressure (RVP) can also be calculated.

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3.8. IDEAL STAGE AND MASS+HEAT TRANSFER COLUMN TYPES

ProMax offers both Ideal Stage (equilibrium-based) and Heat + Mass Transfer (non-equilibrium-based) calculation models. Both models are powerful tools for examining column performance.

Ideal Stage

Ideal Stage models are often used in the design process when determining column configuration, optimum reflux, and other operating conditions. Since the calculations are relatively simple, the ideal stage models solve quickly, and generally give consistent results. These models can be used for all applications, with no need to research correlations for unusual systems or limitations against two liquid phases.

There are 3 column types available when using ideal stage models:

General Ideal Stage – A general equilibrium-based tower type for most distillation types.

TSWEET Kinetics – Designed for amine absorption of acid gases, this model accounts for the rate-dependent kinetic effects of the slower reaction rate of CO2 with amines, and is required for accurate predictions. Some column hardware information must be user-defined.

TSWEET Stripper – Created for amine regeneration, this model assumes a 50% efficient column, operating with a condenser and reboiler, at reasonable pressures and temperatures. No hardware is required to be user-set, however the number of stages should be set keeping in mind the 50% efficiency inherent to the model. If using a thermosyphon reboiler, or operating at unusual conditions, please see the Promax Help or contact Support for assistance.

Mass + Heat Transfer

Mass + Heat Transfer models account for non-equilibrium behavior in a column. This model type allows the user to specify the actual number of trays or height of packing, without making assumptions on the HETP or column efficiencies. Correlations for many applications are available within ProMax. Mass + Heat Transfer columns provide multiple correlation options and adjustable parameters for matching operating data and adjusting predicted performance. This model requires detailed column hardware information for all trays and packing columns.

There are 2 column types available when using Mass + Heat Transfer models:

General Mass + Heat Transfer – A general Mass + Heat Transfer model for most distillation types.

TSWEET Absorber / Stripper – Created for amine absorption and regeneration kinetics.

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3.9. EXPORT / APPEND PROJECT

ProMax has the ability to export entire projects to be appended to other ProMax projects. This is a simple two-step process that will import all streams, blocks, specifications, calculators, Environments, User Value Sets, and other information from one project into another project.

1. Within the project to be exported, select the “Export Project” option in the “File” menu. Save the file as a “.pmxexp” file type.

2. With the destination project open, select the “Append Project”

option in the “File” menu and browse for the desired “.pmxexp” file.

This process will import the entire project to the new project.

Tip If this option is used often for specific processes, it is recommended to have single flowsheets for each process so they can easily be combined into the new project.

3.10. PROMAX REPORTS

ProMax provides several options for generating a report after a project has been completed. The Report Options window shown below is accessed by clicking the “Report” button in the ProMax Ribbon.

1. Optionally supply a Client Name, Location and Job. This will be added to the first page of the report.

2. Choose the output file type, most commonly Word or Excel format. “Template” allows the use of a customized report designed in Excel. Information can be found in the Help, or by asking BR&E Support.

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3

4

5

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3. Units configuration should be set here. By default, ProMax will override any unit changes that have been made in streams and blocks so that the same units will be displayed throughout the report. If the “Override Units” checkbox is unselected, unit changes made for individual streams or blocks will stay as the selected units for the report. This section also allows for the report to be displayed based on Fraction or Percentage and Absolute or Gauge pressures, regardless of how the project was created.

4. The tree control diagram allows the user to select which pieces of information are included in the report. To report the entire project, check the top-most box. A user may select individual flowsheets, process streams, Environments, User Value Sets, or almost any other desirable combination to report.

5. Which stream properties to report are selected here. The selected properties may be rearranged into any order. Selected options are “checked” and found at the top of the list. The composition bases available are listed to the right.

6. Block options are available below the stream options. The selections here will vary depending on the project, but can include various plots or analyses that the user may want included in the report based on the blocks in the project. Heat exchanger specification sheets can be created from the options, and are available if the Word report format is selected and a rated exchanger is included in the simulation.

7. If the user would like either the drawing of the flowsheets or the warnings summary included with the report, they can select the corresponding options in the window.

Select “OK” when the selections are complete. ProMax will then open a dialog asking for a file save location, and then the report will be created.

The “Report Navigator” tool will appear when the Report is opened, and can assist in finding information from a generated report. This navigator does not use a license, but is only available on computers with ProMax installed.

3.11. GIBBS MINIMIZATION REACTORS IN PROMAX

Defining Reactors

This course will focus exclusively on Gibbs Minimization reactors in ProMax. Stoichiometric equations are not required for this reactor type; rather, equilibrium is determined by minimizing the product free energy. This is a good estimation when there is sufficient energy available for the reactions to overcome any activation energy barriers and go to equilibrium. In ProMax, select “Gibbs Minimization” from the “Type” field to enable these estimations.

In many cases, reactors do not have sufficient energy for all possible reactions to occur that are predicted by Gibbs Minimization estimations. To account for this, ProMax has a family of Gibbs Set constraints, with each member designed for specific purposes (see Page 18 for a complete list of Gibbs Sets).

Along with choosing the correct Gibbs Set, all reactors need a pressure drop to be defined.

The “Bypass Fraction” setting reflects the percent of material that passes through the reactor without reacting. This value can be used to estimate reactor efficiencies as well as the effects of catalyst deactivation over time.

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3.12. UTILIZING SHORT MONIKERS AND THE MONIKER CLIPBOARD

A moniker in ProMax is essentially the name given to each object or property within the project. As seen throughout the program, such as when adding variables in solvers and specifiers, finding these monikers in ProMax often leads the user to expand through a “tree” diagram with (+) signs opening to sub-categories.

Two shortcuts are available to find a moniker.

The first option copies the moniker value to a clipboard within the project. This is performed by right-clicking on the property (e.g. stream flow rate or temperature) to be used in a specifier, solver, or property table within the project. Select the “Copy Moniker to Clipboard” option from the context menu.

Later, when selecting this variable, choose the “Clipboard” option at the top-right above the tree diagram. Note that only one moniker may be on the clipboard at a time.

The second option creates a named local variable that is stored within the project and can be referenced at a later time. This is performed by right-clicking on the property to be used, and selecting “Add to Short Moniker List”. Name the variable in the dialog and “Add/reset” the moniker.

Once created, this local variable can be accessed from any moniker location by choosing the “Short Moniker” option located above the tree diagram. Note that not all variables, such as compositions, can be added as short monikers or to the clipboard using the right-click feature.

Tip

The Moniker Builder button in the ProMax ribbon (pictured at right) allows the user to create short monikers and add variables to the clipboard using the tree diagram as opposed to right-clicking on the desired variable. With this button, short monikers can be made for any variable, including compositions.

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Optimizing A Model 4.1. OVERVIEW

There are extensive optimization options available within ProMax. ProMax simulations can interact with Excel to import & export data between the two programs, and can also be used along with ProMax to run case studies or sensitivy studies to help understand and predict a unit’s behavior. Microsoft VBA coding provides additional opportunities for project customization.

Calculators can be used to automate simulations and optimize process conditions. Simple Specifiers are used to set the value of a property based on the value of other known variables or constants. Simple Solvers automatically adjust a parameter to maintain a spec or goal elsewhere in the process. User Value Sets can be created to store user-defined variables for additional calculations.

4.2. EXCEL INTERACTIONS

ProMax has several methods to interact with outside programs, most notably Microsoft Excel. The following pages outline how to use the two most popular Excel applications: Import/Export and Scenario Tool™.

Import/Export from Excel

The simplest Excel interaction is the import/export functionality that is available between ProMax and an embedded Excel workbook.

To embed a workbook, select the “Add Excel Workbook” option from the ProMax Ribbon. This workbook is embedded within ProMax and will open, close, and save with the project. It is not available outside of the ProMax project unless a copy is created in another Excel workbook that is not connected with ProMax.

Once an Excel workbook is embedded, right-clicking on most properties in ProMax will give an option for “Export to/Import from Excel”. Selecting this allows the user to choose the preferred unit set to be transferred with the value, along with the cell in Excel where the property will be connected.

Both exporting and importing are allowed if there is no value in the ProMax field; however, if there is a value in the ProMax field then importing options will be disabled and only exporting will be allowed. To delete an incorrect or unwanted Export/Import connection, right-click on any property and select “Delete Exporting to/Importing from Excel” to bring up a list of all existing Export/Import connections.

Tip

Compositions are exported as an array from the top of the components list down. Select a range of cells that corresponds to the number of components to export. For example, if the component list has 15 items and only 5 cells in Excel are selected, the top 5 components will be exported. Individual component’s composition within the list cannot be exported with this tool, as selecting one cell will always export the top component in the list. Individual components can be exported using the Scenario Tool, which is explained on the following page.

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Using the Scenario Tool™ in ProMax

ProMax includes an Excel Add-in that allows the user to create case studies for any unit created in ProMax. The Scenario Tool™ may be used in either an embedded or external Excel workbook. This tool provides access to all of the functionality of Excel, such as creating graphs or using “in-house” worksheet formulas for manipulating and interpreting data.

1. Open an Excel sheet and look for the tool under the ProMax ribbon.

2. If the Scenario Tool is not already available under the ProMax ribbon in Excel it can be added manually by double-clicking the ProMax Scenario Tool.xla file at the following default locations:

ProMax 4.0: C:\Users\Public\Documents\Bryan Research & Engineering Inc\ProMax4\AddOns\Excel.

ProMax 3.2: C:\Program Files (x86)\Bryan Research & Engineering Inc\ProMax3\AddOns\Excel.

3. Start the Scenario Tool in Excel by clicking on the “Scenario Tool” option.

4. Select from the drop-down list the appropriate ProMax file to be used. A name can be given to the scenario, and the “Manage Scenarios” button to the right allows for handling multiple scenarios.

5. Organize in Excel the input parameters to be supplied to ProMax and the output locations to display the calculated results.

6. Add the Input variables to the Tool by using the “Add Variable” button in the ProMax Inputs section. Use the “Select ProMax Object” button to select the desired ProMax variable. Name the variable, select the desired Excel range for this variable, and verify the units are correct.

7. Add the Output variables by using the “Add Variable” button in the ProMax Outputs section.

8. Run the tool, selecting which set of “runs” to execute.

Tip The EZ Setup Tool opens a “wizard” to help set up a scenario step-by-step, and the 2D Grid Setup Tool is designed for easily setting a grid with two input variables and one output variable, respectively.

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4.3. USING CALCULATORS IN PROMAX

Using Simple Specifiers in ProMax

A Simple Specifier is used to set the value of a property based on the value of other known variables or constants. To set a specifier, right-click on the property to be calculated, then select Create Simple Specifier.

1. Name the Simple Specifier.

2. Write the expression that defines the specified variable. This must be a single-line expression, but can have multiple independent variables. Note that the independent variables must be known and calculated prior to the specified variable being used.

3. A unit selection is also made. ProMax will maintain this selection even if project units are altered.

4. Select the Add button to add the Independent Variables to be used in the specifier. The Property Moniker dialog box, as shown to the right, will appear.

5. From the variable selection dialogue, begin expanding the tree through the project, flowsheets, stream or block, down to the desired independent variable. When a valid selection is picked, the gray box below the tree will fill in with a moniker string.

6. Upon selecting the variable, type a unique name to briefly identify the value. This name must not include any special characters, with the exception of the underscore (_); a space will be replaced with an underscore. The name must not start with a number and is case-sensitive.

7. Select Add when finished, and repeat for as many variables as required for the specifier. When an independent variable has been selected it will appear in the Independent Variables list with its name, value, and units as shown below.

Tip Selecting the “Hold” check-box in the Property Moniker dialog box will keep the dialog open after adding the current variable, simplifying the process of adding multiple independent variables.

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Using Simple Solvers in ProMax

A Simple Solver is used to adjust one variable in order to hit a goal or spec on another variable in a process. A Simple Solver must be used if ProMax will need to iterate to find the desired solution.

For example, if the goal is to adjust the flow rate of air fed to a Claus unit to achieve a set tail gas ratio of H2S to SO2, a Simple Solver could be placed in the inlet air flow rate field. ProMax will use the solver criteria to iterate on the air flow rate until it achieves the desired tail gas ratio.

To create a Simple Solver, right click on the property that the solver is to adjust and select Create Simple Solver.

1. Name the Simple Solver.

2. ProMax will iterate the Calculated Variable until the equation written here is equal to zero, so the equation must be written with this in mind.

3. Select the Add button to open a tree dialog as shown in the Specifier example on page 31. Add the Measured Variable to be used. This is the value ProMax will measure to see if it meets the goal (in this case, the tail gas ratio).

4. A guess for the “Calculated Value” must also be supplied to give the solver a starting point. Upper and lower bounds may be set, though this is usually not necessary and will cause the solver to fail if the solution is outside of the given bounds.

5. A Priority must be set if multiple solvers are present in the simulation for acceptable execution time. It is suggested that the solvers be prioritized to solve sequentially, with loops solving from the “inside out”.

Writing the Simple Solver Expression: 1. For this example, the Tail Gas Ratio should equal 2 when solved: TailGasRatio = 2

2. Since ProMax expects to solve at zero, this is rewritten: TailGasRatio – 2 = 0

3. ProMax needs only the function written, so the “0 = ” is omitted: TailGasRatio – 2

Tip

While writing the function as “TailGasRatio – 2” is acceptable, it is highly recommended that each Simple Solver expression be “normalized” to aid in convergence. Normalizing the above expression results in the following: “TailGasRatio/2 – 1”

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4.4. USER DEFINED VARIABLES

ProMax provides a method to define a variable that it does not calculate otherwise. These variables are stored in User Value Sets, so they may be grouped together as desired. To add a new user-defined variable:

1. Open the Project Viewer and select (double-click) the User Value Set from the tree diagram in which to add the new variable. If a new User Value Set needs to be created, right-click on the “User Value Sets” option in the tree diagram of the Project Viewer and select “Add”.

2. It is recommended to change the name of the User Value Set to something descriptive.

3. Select “Add…” to create the new variable.

4. From the new dialog box that appears, tell ProMax what type of unit this variable will have associated with it. There are three choices:

a. User Defined Units – Define units for this variable based on units ProMax can understand, but in an unusual sequence that is not available in the “Standard Units” list (e.g. kW*h/ft2). ProMax can perform unit conversions from these defined units.

b. Unrecognized Units – Define units for this variable based on something ProMax cannot understand, such as monetary units (e.g. $, £). Unit conversions are not available.

c. Standard Units – Select from the list which set of units this variable will have. ProMax will provide a dropdown list of available units as normal.

5. Choose whether to associate this variable with a new Simple

Specifier. Choose to associate with a Simple Specifier if any information must be taken from within the project to calculate this variable’s value (e.g. flow rates, compositions, horsepower, etc…). If the value for this variable will be set directly by the user, leave this unmarked (e.g. setting an ambient temperature for use in the project).

6. Name the variable and select “OK”.

7. If the user has selected to associate this with a Simple Specifier, it will create an undefined specifier. Right-click on the blue box, select “Show Calculator” and define the requirements. Please see Using Simple Specifiers in ProMax on page 31 for further details.

8. If there is not a specifier associated with this variable, the user types the desired value for this variable directly into the parameter box.

9. Lower and upper bounds are optional, but may be set. If the “Enforce Bounds” box is selected, a warning message box will be generated if the variable falls outside either of these bounds.

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Equipment Sizing & Rating Overview 5.1. OVERVIEW

ProMax provides sizing and rating capabilities for many different types of equipment. A variety of separator types can be sized for adequate separation. Column internals can be designed or existing column information can be specified. Relief valve sizing can also be performed within ProMax, along with depressurization calculations for a variety of scenarios. In addition, control valve types can be selected within a ProMax valve block to calculate the pressure drop over the valve.

Heat exchanger internals can be input into a simulation to determine if an existing exchanger will provide sufficient heat exchange. Expected pressure drops through the exchanger are calculated according to the actual exchanger internals.

The following sections provide basic information on sizing applications available within ProMax. These topics are discussed in great detail in the BRE 232 “Equipment Rating and Sizing” course as well as in the ProMax Help.

5.2. SEPARATOR SIZING

Separator sizing can be performed within ProMax to calculate the required size of a separator for adequate separation. Sizing for the following types of separators is available: Horizontal 2 Phase, Vertical 2 Phase, Vertical 3 Phase, Horizontal 3 Phase, Horizontal 3 Phase with Boot, Horizontal 3 Phase with Weir, Horizontal 3 Phase Boot & Weir, or Horizontal 3 Phase Bucket & Weir.

To enable separator sizing, double-click on the separator to be sized and select the “Include Separator Sizing” option on the Process Data tab.

With this enabled, a new Sizing tab is created where sizing information will be calculated. Separators are sized to give the vapor and liquid(s) adequate time to fully separate into their respective phases. Theoretically, there are many different separator sizes that could achieve the desired separation. By default, ProMax calculates the diameter and length combination that will give the smallest overall size required to achieve thorough separation. The diameter can be user-defined, in which case the necessary length will be calculated according to the set diameter.

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Refer to the “Separator Sizing” web tutorial online for an example of how to size a 3-phase separator or refer to the ProMax Help for definitions and explanations of separator sizing parameters.

5.3. COLUMN SIZING

Column sizing can be performed for any ideal stage or mass transfer column. Sizing information is found within the Hardware grouping under the Process Data tab of the column. Within the General section, the user can select whether the column uses trays, random packing, or structured packing. For an existing column a diameter can be specified, from which the fraction flooding will be calculated. Alternatively, for column design cases, a fraction flooding can be set and ProMax will calculate the necessary diameter for the specified amount of flooding. A system factor is set to account for the expected foaming within the tower.

For Ideal Stage models, a Real/Ideal Stage Ratio is specified to illustrate the conversion of real trays into theoretical ideal stages. For example, a ratio of 3 would mean that it takes 3 real trays to match 1 ideal stage. For both ideal stage and mass transfer models, tray and packing information can be specified. Two types of trays are available: Sieve and Round Valve. Many types of random and structured packing are available. User-defined packing types can also be input into the simulation.

For packed columns, the Ideal Stage model utilizes a Height Equivalent to the Theoretical Plate (HETP) value to convert a height of packing into an equivalent number of ideal stages. Mass Transfer modelling allows the user to directly input the total packing height into the tower internals. The total height is broken into increments (represented as stages) whereupon the calculations are performed.

For additional information on column internals, including differences between ideal stage and mass transfer models, contact Technical Support.

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5.4. DEPRESSURIZATION AND RELIEF VALVE SIZING

Depressurization events can be modelled with the Depressurization Example stencil inside the ProMax Property Stencils. This stencil allows the user to calculate the orifice diameter necessary for depressurization along with the maximum flow rate through the orifice. For a known orifice size this stencil can also calculate the time required for depressurization or the amount of depressurization that would occur given a specified amount of time. Heat input can be accounted for, including fire case calculations defined by API 521.

Relief valve sizing for blocked flow cases can be performed within any stream using the Relief Valve Sizing analysis. The analysis calculates the required effective discharge area based on the stream composition and user-specified parameters such as valve type, relief temperature, relief pressure, and back pressure.

5.5. CONTROL VALVES

Control valve specifications can be input directly into a valve block. Control valve calculations are performed by selecting “Control Valve” as the Pressure Drop Method on the Process Data tab and then specifying the valve Type, Identifier, and Opening. ProMax calculates the resulting Valve Cv and Pressure Drop for the specified control valve.

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5.6. HEAT EXCHANGER RATING

Heat exchanger internal information can be specified in ProMax for rating existing exchangers in a simulated process. The following heat exchanger types are available for rating: Shell & Tube, Fin Fan, Compact, Double Pipe, and Plate Frame exchangers.

To enable a rating for an exchanger, double-click on the desired exchanger, go to the Process Data tab, and then select the Enable checkbox at the bottom of the Heat Transfer grouping.

A new Rating tab is created where the exchanger internals are input and the results are dispalyed. The type of internal information required depends on the type of exchanger (number of tubes for shell & tube exchanger, number of layers for compact exchanger, etc.). A fraction over design (FOD) will be calculated for all types of exchangers to compare the currently simulated conditions with the actual capacity of the exchanger. A negative FOD means the existing exchanger is insufficient for achieving the stream conditions set in the simulation. Often a Simple Solver is placed on an exchanger duty or outlet temperature to achieve an FOD of 0%, resulting in a properly fit heat exchanger.

Exchanger rating also provides essential information specific to each side of the exchanger, such as an expected pressure drop calculation for each side. The user also has the ability to enter a fouling resistance for each side to help account for the prolonged use of an exchanger.

The exchanger rating feature can also be used for basic heat exchanger design. Please refer to the “Heat Exchanger Sizing” web tutorial online for an example of how to design a heat exchanger using ProMax rating capabilities.

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Course Exercises

Exercise 1: SIMPLE GAS PLANT

Process Background: Collection and Pre-Processing

Natural gas liquids (NGLs) recovered through natural gas processing are often stored until they are trucked or piped away for processing. To avoid excessive emissions and losses, the liquid products may be “stabilized”. The stabilization process heats the liquids to allow the most volatile components to vaporize, lowering the vapor pressure of the remaining NGL product.

Note that for all exercises the alternative specifications in metric units have been rounded for convenient values and are therefore not exact unit conversions.

Goal and Information

This simple system models a gas feed separated into a liquid product and a sales gas by compressing, cooling, and flashing the gas. The liquid is sent to a stabilizer to achieve product specifications by removing lighter components in the stabilizer overheads. The column is operated with a reboiler that is used to control the composition of the bottom liquids.

Configure the Environment by selecting an appropriate property package (Peng-Robinson or SRK) and adding the listed components.

Use the stream conditions in the table to define the inlet stream.

The compressor outlet pressure is 725 psig [50 barg]. Use 75% polytropic efficiency.

The outlet of the air cooler should be 110°F [43°C]. A pressure drop should be set in the cooler.

Sales gas is sent through a gas/gas exchanger to cool the inlet stream. The Minimum End Approach Temperature in this first cooler is 30°F [16°C]. Two pressure drop specifications are required for a two-sided exchanger.

The second cooler chills the stream feeding the propane cooler to 36°F [2°C]. Set the pressure drops.

The propane refrigeration cools the stream entering the low temperature separator to 20°F [-6.5°C]. Set a pressure drop.

Set a pressure drop of 0 psi in the LTS.

The pressure at the outlet of the JT valve is 200 psig [14 barg].

The column has 8-stages with a 4 psi [0.28 bar] pressure change.

Common NGL product specifications include: C1 < 0.5 liquid volume percent (LV%) of the NGL product stream; and a C1/C2 LV% ratio < 0.015. Inside the stabilizer on the Specifications tab, create both of the specifications mentioned here (see the FAQ on the next page for assistance). Set the C1/C2 ratio as a Specification and leave the C1 LV% as a Calculation.

Inlet Conditions

Temperature 95°F [35°C]

Pressure 200 psia [14 bar]

Flow 5 MMSCFD [5600 Nm3/h]

Composition Mole %

Nitrogen 1.92

Carbon Dioxide 2.71

Methane 58.66

Ethane 16.17

Propane 12.86

i-Butane 1.58

n-Butane 0.70

i-Pentane 0.84

n-Pentane 3.73

n-Hexane 0.81

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Once the unit has solved, recycle the Stabilizer gas stream to the beginning of the system. Supply a guess for stream “Recycle Guess”, including temperature, pressure, flow rate and composition. A good guess is to mimic stream 13 from the previous solution by clicking the “Copy Inlet” button inside the recycle block.

QUESTIONS 1. Insert a Property Table to display the temperatures, pressures, flow rates, and compositions of the Inlet, Sales

Gas, and NGL streams.

2. What is the LMTD in the first cross exchanger and the sales gas temperature?

3. What is the duty required for the C3 refrigeration unit?

4. Generate a phase diagram with only the dew point and bubble point lines for the sales gas stream. See the FAQ section on the next page for an explanation of how to create a phase envelope diagram.

5. Add the 90% and 10% vapor lines to the phase diagram.

6. What are the critical point and the cricondentherm temperature for the sales gas?

7. What are the Reid Vapor Pressure (RVP) and True Vapor Pressure (TVP) of the liquid product? Display these on the flowsheet using a Callout.

8. The pressure drop in the inlet stream is to be maintained below 5 psi/100 ft [1 bar/100m] of horizontal length. Using schedule 40 pipe, what diameter is required? What is the actual pressure drop? What is the velocity?

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FAQs on Exercise 1

All heat exchangers normally have a pressure drop specified, since this is a property of the exchanger. Setting an outlet pressure instead can result in unexpected results if conditions change later.

Generally, an efficiency is set for all pumps, compressors, and expanders. Setting both the outlet pressure and temperature is strongly discouraged because a small inaccuracy in the temperature can result in efficiencies less than 0% or greater than 100%.

Visio shapes can be resized and rotated by utilizing points that become available when the object is selected. Process and Energy streams can be redirected from similar points.

a. The small green circle above the exchanger to the right is for rotating the shape; a few shapes restrict this to maintain correct positioning of vapor and liquid exits.

b. The other green squares are to resize and stretch the shape c. The yellow diamond, as show on the “20” in the stream to the right,

designates label location; labels can be moved by dragging this diamond. d. To redirect streams, find the small bright-green squares located in the

middle of the streams, then click and drag from these points.

When the definition of a property in ProMax is unknown, often the “What’s This” Help menu can provide some assistance. This feature is found by right-clicking on most cells in the Project Viewer:

The Callout box option is found in the “ProMax Streams” set, and contains several set-up options to customize the display. The “Font…” button gives control over the font size, color, and type. The “Color…” button allows changes to the gridline colors.

For the Column Specifications mentioned, use “Component Flow” for C1 in total bottoms liquid stream and “Component Ratio” for the methane to ethane ratio.

Recycle blocks always require the outlet PStream to be completely specified (Pressure, Temperature, Flow Rate and Composition).

Many additional stream properties (such as the Phase Envelope, Vapor Pressure, Line Sizing, etc.) are calculated within the different analysis available in a stream under the Analysis tab. For a comprehensive list of analysis available in ProMax, see page 24.

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Exercise 2: PIPELINE SIMULATION

Goal and Information

Two different natural gas lines are mixed and sent through 17.3 miles of pipeline to a processing facility. Along the way, a 3rd gas stream from a different production facility is added to the mixture. Build a simulation to represent this system based on the information below.

PIPE-1:

Segment 1: 24,000 ft [7315 m] length 8 in [200 DN], schedule 80 Ambient T = 50°F [10°C]

Segment 2: 45° standard elbow

Segment 3: 25,000 ft [7620 m] length 8 in [200 DN], schedule 80 500 ft [150 m] elevation rise Ambient T = 40°F [5°C]

Segment 4: 30,000 ft [9140 m] length 8 in [200 DN], schedule 80 Ambient T = 30°F [-1°C]

PIPE-2:

Segment 1: 2.3 mile [3700 m] length 10 ft [3 m] elevation rise 12in [300 DN], schedule 80 Ambient T = 40°F [5°C]

The heat transfer coefficient should be calculated by ProMax based on Carbon Steel A134 welded pipe with a centerline buried depth of 24 inches [600 mm] in dry clay ground.

QUESTIONS 1. What is the temperature and pressure of the gas exiting the pipeline to the processing facility?

2. What is the calculated overall heat transfer coefficient for the first pipe segment?

3. For each pipe segment, plot length vs. pressure.

4. Where does drip condensate begin to form? How much liquid (bbl/d) exits Pipe-2?

5. If the upstream dehydration facility shuts down and Gas 1 becomes saturated with water, do hydrates form?

Stream Gas 1 Gas 2 Gas 3

Temperature 100°F [37°C] 100°F [37°C] 70°F [21°C]

Pressure 600 psig [41.5 barg]

600 psig [41.5 barg]

510 psig [35.2 barg]

Flow rate 8.2 MMSCFD [9153 Nm3/h]

5 MMSCFD [5575 Nm3/h]

8 MMSCFD [8930 Nm3/h]

Composition Mole % CO2 0.2 0.3 0.1 N2 0.5 0.3 0.8 C1 84.3 86.9 85.1 C2 5.5 4.8 6.5 C3 5.1 4.1 3.8 iC4 1.4 0.9 1.1 nC4 1.5 1.3 1 iC5 0.85 0.7 0.6 nC5 0.3 0.3 0.5 nC6 0.3 0.2 0.37 nC7 0.05 0.2 0.13

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Exercise 3: SIMPLE MDEA SWEETENING UNIT

Process Background: Acid Gas Removal

The removal of acid gases, specifically hydrogen sulfide (H2S) and carbon dioxide (CO2), can be achieved through several methods, including the use of: solid scavengers (e.g. iron sponges, etc.), chemical solvents (e.g. MEA, DGA, MDEA, caustic, potassium carbonate, etc.), physical solvents (e.g. MeOH, DEPG, NMP, etc.), and membranes. Some recently developed processes reduce the H2S in the natural gas directly to solid sulfur using liquid catalysts or biological pathways. The chosen method depends on the temperature, pressure and inlet gas composition.

An example of a chemical solvent process can be found in this exercise, while an example of a physical solvent process can be found in the Physical Solvent Acid Gas Removal exercise on page 71. Further examples of chemical and physical solvent processes can be found in the example projects located at FileOpen Example ProMax Project. The chemical solvent examples are contained in the “Amine Sweetening” directory and the physical solvent examples can be found in the “Gas Processing” directory. See the ProMax Help topic for information on modeling membranes.

Chemical solvents Chemical solvents usually consist of one or more amine compounds mixed with water. The solvent is brought into intimate contact with the gas in an absorption column that typically has ~20 real trays or equivalent packing. In the absorber, the acid gases are absorbed into the solvent and react with the amine (a weak base). This process is kinetically-limited. Primary amines (e.g. monoethanolamine (MEA), diglycolamine (DGA), etc.) have the fastest kinetics, secondary amines (e.g. diethanolamine (DEA), diisopropanolamine (DIPA), etc.) and tertiary amines (e.g. methyl-diethanolamine (MDEA)) have respectively slower kinetics. ProMax accounts for kinetic effects with a rigorous rate-based kinetic model.

While primary and secondary amines can absorb H2S and CO2 quickly, they are typically used at lower concentrations and with a reclaimer to reduce the amount of amine loss and degradation. Tertiary amines can be used at higher concentrations and the reaction kinetics favor selective absorption of H2S over CO2. Typically, these tertiary amines have no reclaimer since their degradation and losses are much lower.

If the absorber is operated at high pressure the rich amine is sent through a flash tank to reduce the amount of hydrocarbons present in the rich amine before it reaches the regenerator. A lean/rich heat exchanger is also commonly used to reduce reboiler duty.

The regenerator is a distillation tower that typically has ~20 real trays. It is operated at the lowest pressure feasible for downstream processing of the acid gas, typically near 15 psig [2.05 bara]. The reboiler often uses saturated steam at 50 psig [4.5 bara] and a flow rate equivalent to 0.7-1.5 lb steam/gal [90-180 kg steam/m3] of circulating solvent. A condenser is also present to reduce the amount of amine loss and to reduce the amount of water sent down-stream.

Additional information on optimization of sweetening systems can be found in the “BRE 231: Sour Gas Processing” course or within the ProMax Help.

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Goal and Information

In this exercise, a sweet gas is required to have less than 2 mol% CO2 and less than 4 ppm H2S (molar). Use the following information to simulate this amine sweetening unit and determine if the requirements are being met. Use an Amine Sweetening property package, as there are ionic reactions occurring. Use the “Exercise 3 – Simple MDEA Sweetening Unit.pmx” file.

Part A: Ideal Stage Model

Select an appropriate Amine Sweetening Environment.

The inlet gas stream is 100% saturated with water

Supply a guess for the recycle block outlet.

40 wt% MDEA is circulated at 190 sgpm [44 m3/h]. The makeup stream is at ambient temperature and 20 psig [1.4 barg].

The pump increases the lean amine pressure high enough to return to the absorber column.

The air cooler outlet temperature is set to 10°F [5°C] warmer than the gas feed temperature.

The absorber uses the “TSWEET Kinetics” column type that has a 4 psi [0.3 bar] pressure drop.

The absorber diameter is 4 ft [1.3 m]. Set a system factor of 0.8.

Set the real/ideal stage ratio to 3. This represents the fact that 3 real amine absorber trays are equivalent to 1 ideal stage (amine absorbers are about 33% efficient).

Weir height is 3 in [7.6 cm] and tray spacing of 2 ft [0.6 m].

The rich flash tank operates at 100 psia [6.9 bar].

The rich amine enters the regenerator at 210°F [99°C].

The regenerator top stage pressure is 12 psig [0.82 barg] with a 4 psi [0.3 bar] pressure change through the tower. Remember to use the “TSWEET Stripper” column type.

The condenser operates at 120°F [50°C] and the reboiler duty is 17 MMBtu/h [5000 kW].

Inlet Conditions

Temperature 100°F [38°C]

Pressure 1000psia [70 bar]

Flow 50 MMSCFD [56000 Nm3/h]

Composition Mole %

H2S 1.5

CO2 3.5

Methane 83.4

Ethane 5.65

Propane 4.07

n-Butane 0.9

n-Pentane 0.5

n-Hexane 0.32

n-Heptane 0.15

Benzene 0.005

Toluene 0.002

Ethylbenzene 0.001

o-Xylene 0.002

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QUESTIONS 1. What are the sweet gas CO2 and H2S compositions?

2. What are the liquid residence time and percent flood on an absorber tray?

3. What are the H2S, CO2, and total rich loadings (mol/mol)? Lean loadings?

4. What are the lean and rich approach in the absorber for H2S?

Part B: Trayed Tower Using Mass + Heat Transfer Model

One advantage of the Mass + Heat Transfer Model available in ProMax is the ability to directly specify the number of trays in the column.

Change the absorber tower to use the “Mass + Heat Transfer” model, and select the “TSWEET Absorber/Stripper” column type.

Increase the column stages to 20.

From the “General” selections, keep a 4 ft column diameter, and a system factor of 0.8.

From the “Tray” selections, use Sieve trays, and maintain the 2 ft spacing and 3 in weir height.

Solve the flowsheet again. How do the results compare?

FAQs on Exercise 3

The Saturator block is used in this exercise to fully saturate the sour feed stream with water. The “Water” stream requires only that a composition of 100% water is set. Allow ProMax to calculate other properties. The default setting for the block is to saturate the process stream to 100% saturation.

The Lean and Rich Approach are column specifications used to determine the best way to improve absorber performance. They are also used to predict absorber stability during process upsets.

o Lean Approach: Analyzes the driving force at the top of the absorber. If the lean approach is too high (>80%) then the lean amine acid gas concentration feeding the tower is high and there will be little driving force to move acid gas into the amine at the top of the column. Increasing the reboiler duty will lower the acid gas concentration in the lean amine and thus increase the driving force at the top of the column.

o Rich Approach: Analyzes the driving force at the bottom of the column. If the rich approach is too high (>80%) then the amine solution will approach equilibrium with the incoming feed and there will be little driving force to move acid gas into the amine at the bottom of the column. Increasing the amine flow rate will increase the capacity for pickup and increase the driving force at the bottom of the column.

The Make-up / Blow-down block controls the composition and flow rate of any make-up stream required – more details can be found on Page 10. The Make-up stream requires a user-set temperature and pressure.

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Exercise 4: EXPORT/APPEND PROJECT

ProMax provides a simple method to combine different projects. The options may be found in the File menu as “Export Project” and “Append Project”. In this exercise, an export file of the amine unit from Exercise 3: is created and appended to an existing template project of a dehydration unit.

PROCESS INFORMATION

From the file menu, select “Export ProMax Project…” Save the project in an easily accessible location, and close the file.

Open the file named “Ex5 - TEG Unit.pmx”.

From the file menu, choose “Append ProMax Project…” Browse and select the “.pmxexp” file from step 1.

From the TEG flowsheet, select “Active Flowsheet”. Then Duplicate the MDEA Environment and rename the resulting Environment “TEG Environment”. Assign the property package “SRK” to the Environment, and leave the components unchanged for now. Select OK, and then assign the “TEG Environment” to the TEG flowsheet.

Flow Multiplier

On the MDEA flowsheet, to double the flow rate of the sweet gas, use the ProMax Property Stencil named “Inline Flow Multiplier ”. Doubling the flow rate can be used to represent having two identical amine trains that mix before further processing. Allow this shape to propagate the pressure and enthalpy and set the outlet flow rate as double the inlet flow rate. The composition will always be unchanged when using this block. The Property Stencil set is found in the “More Shapes” menu, if not already available in the project.

Drop a Cross Flowsheet Connector, found in the “ProMax Streams” stencil, onto the MDEA page near the Inline Multiplier outlet stream. Select the TEG flowsheet as the connected page. Connect the Inline Multiplier outlet stream to the inlet of the Cross Flowsheet Connector as shown below.

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On the TEG flowsheet, connect the second side of the Cross Flowsheet Connector (which appears in the lower lefthand corner of the flowsheet by default) into the dehydration unit “Wet Gas” stream.

QUESTIONS 1. Is there a temperature difference between the “Sweet Gas” stream in the MDEA flowsheet and on the TEG

flowsheet? Why? How can this be corrected? (Incorporate this change into the project.)

2. Since the component list from the MDEA unit earlier was duplicated, the current TEG Environment is lacking the component TEG. When adding TEG to the Environment, also delete the MDEA from the list. Why will the cross-flowsheet connector no longer solve?

3. In the Cross Flowsheet Connector, a Mole Fraction Transfer Threshold can be set to prevent the transfer of trace components across flowsheets. This can be useful in cases where the user wants to remove a trace component from the components list across different units. In this exercise, set the Threshold value to limit transfer to only those components above 5 ppm. What components will not be transferred to the Dehy Flowsheet? What issues does this raise? Change the Threshold value to 1.5 ppm.

Tip

The “Copy Stream Conditions” property stencil is an alternative that will display both inlet

streams. The shape connects to a reference stream and a blank target stream with connector lines, as illustrated. Composition, mass flow rate, molar enthalpy and pressure are transferred.

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Exercise 5: GLYCOL DEHYDRATION UNIT

Process Background: Glycol Dehydration

Water content of a gas stream often needs to be adjusted to meet specifications for transmission pipelines, storage, or further processing. There are two methods currently employed in most dehydration systems: direct injection or a contactor column. Ethylene glycol (EG) and methanol are typically used in the injection method, and triethylene glycol (TEG) is typically used with the contactor column.

A contactor column with packing or trays is used to allow intimate contact between the wet gas and glycol. These towers typically have 2-3 ideal stages. Lean TEG is fed to the top of the tower and contacts the vapor stream coming up from the bottom. The TEG preferencially absorbs water from the gas stream. This rich TEG is then regenerated by removing the water in a regenerating column. The regenerating column typically consists of a very large reboiler with a small packed tower.

In general, about 2-5 gallons of TEG are circulated for every pound of water in the wet inlet gas. The reboiler temperature should not exceed the glycol degradation temperature, approximately 400°F [204°C] for TEG systems. It is also common practice to cool the temperature of the lean glycol entering the contactor to about 10°F [5°C] above the inlet gas temperature since colder temperatures improve absorption.

Though glycols do preferentially absorb water, aromatic hydrocarbons also show limited solubility in glycols. As a result, if the feed gas contains even small amounts of aromatic compounds, non-negligible amounts of these may be absorbed. Depending on Environmental regulations, the exhaust gases from a glycol dehydration process may need to be monitored and/or treated for aromatic compounds.

Additional information on optimization of dehydration systems can be found within the ProMax Help or in the BRE 231: Sour Gas Processing course.

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Goal and Information:

Simulate a TEG unit that dries the inlet gas to a water content of less than 7 lb H2O/MMSCF (110 mg/scm).

Part A: Ideal Stage Model

Use the appended project created in the previous exercise. If starting here, use the conditions in the table and add a Saturator block to saturate the inlet with water.

The Wet Gas stream is cooled to 100°F [38°C].

Specify a complete guess for the recycle outlet.

Use 5.6 sgpm [1.3 m3/h] for the glycol circulation rate. Makeup is 99.9 wt% TEG and 0.1 wt% H2O.

The absorber has 2 ideal stages, and the regenerator has 4 ideal stages.

The rich flash operates at 60 psig [5.2 bar].

The rich feed to the regenerator is heated to 300°F [150°C].

The regenerator reboiler operates at 390°F [200°C].

The regenerator operates at atmospheric pressure with a small reflux ratio generated from the reflux coil.

Use an estimate of 20,000 BTU/h [6 kW] inside the Q-Recycle block.

*Only use table if previous exercise not worked

Inlet Conditions

Temperature 125°F [50°C]

Pressure 990 psia [68.5 bara]

Flow 96.6 MMSCFD [107 800 Nm3/h]

Composition Mole %

H2S 3.3 ppm

CO2 1.31

Methane 86.63

Ethane 5.87

Propane 4.23

n-Butane 0.94

n-Pentane 0.52

n-Hexane 0.33

n-Heptane 0.16

Benzene 0.005

Toluene 0.002

Ethylbenzene 0.001

o-Xylene 0.002

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QUESTIONS 1. What is the water content (lb/MMSCF) of the dry gas? The water mass concentration in the Lean TEG stream?

Display these in Callout Boxes on the flowsheet.

2. At what temperature will hydrates form in the dry gas?

3. What is the mass flow of water in the feed gas?

4. How much BTEX (ton/yr) leaves in the Water Gas stream?

5. Create a customized ProMax report for the project. For additional information on reporting see page 26.

Part B: Packed Tower Using Mass + Heat Transfer Model

One advantage of the Mass + Heat Transfer Model available in ProMax is the ability to directly specify a height and type of packing in the column. Change the contactor tower to use the “Mass + Heat Transfer” model, and select the “General Mass + Heat Transfer” column type.

Increase the column “stages” to 6. This number for a packed column represents the number of calculation increments. Generally, each increment should represent approximately 18 in. [0.5 m] of packing.

From the “General” selections, choose “Structured” packing, a 4.25 ft. [1.3m] column diameter, 10 ft. [3m] column height, and a system factor of 0.6.

From the “Structured” selections, choose “Sulzer Mellapak® 350.X metal” as the packing type.

Solve the flowsheet again. How do the results compare?

Optional Extended Exercise – Stripping Gas in Dehydration

Goal: See the improvement the use of stripping gas will give to the Exercise 5: Glycol Dehydration Unit model.

PROCESS INFORMATION

Modify the process to feed 18 SCFM [34 scm/h] of the dry gas stream as stripping gas into the reboiler (approximately 3 SCF / gallon glycol circulation). Preheat the stripping gas stream to 350°F [177°C], and then lower the pressure to 20 psig [1.4 barg]. What is the new water content of the dry gas?

FAQs on Exercise 5

Why is there no flow from the rich flash tank to the regenerator?

This generally occurs if a 3-phase separator is used, but the current conditions only result in 1 or 2 phases. The separator block in ProMax defaults to the “Light Liquid” outlet for the Main Liquid Phase regardless of the composition. To change the behavior of the separator, change the “Main Liquid Phase” option within the separator block to “Heavy Liquid”.

Stream water content (lb/MMSCF) and hydrate formation temperature can be found in the “Freeze Out, Hydrate, H2O Dew Point” analysis.

Use the “Composition Subset” analysis to quickly calculate the amount of BTEX (or other groupings) in a stream.

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Exercise 6: SIMPLE TURBOEXPANDER DEMETHANIZER

Process Background: Gas Processing

Raw natural gas coming from the well will contain varying amounts of ethane, propane, n-butane, isobutane, and pentanes. These compounds comprise what is called natural gas liquids (NGLs). These NGLs are removed from the methane, which is sold as “natural gas.”

The NGLs are typically removed before the natural gas is introduced to the transmission pipelines. This helps to maintain the quality of the natural gas within regulations and minimize liquids formation in the pipeline. The removed NGLs can be used as raw material for chemical plants, in enhanced oil recovery, and as a fuel source. Thus, NGL products are often more profitable than natural gas and so improved recovery is desired.

The NGLs are removed in a demethanizer column. The methane, at pipeline purity, is recovered at the top of the distillation column. Depending on the economic situation, ethane will either be sent out the top along with the methane (known as “ethane rejection”) or recovered in the bottom liquids (“ethane recovery”). All other heavier hydrocarbons are recovered in the bottom liquid stream where they go on to be fractionated into different marketable products. Demethanizers are operated at very low temperature ranges (e.g. -150°F [-100°C] at the top) and at moderate pressures around 200-300 psig [14-21 barg].

The temperatures and reboiler requirements for the demethanizer usually result in the use of a “cold box” exchanger. This is often a compact exchanger exchanging energy with multiple streams (often 4-5 different streams). These compact exchangers can achieve closer approach temperatures than shell & tube exchangers and are designed to handle much lower temperatures. ProMax has the ability to both model and rate these exchangers.

Additional information on optimization of turboexpander systems can be found in the “BRE 201: Gas Processing” course or within the ProMax Help.

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Goal and Information

This exercise continues from Exercise 5: Glycol Dehydration Unit. Alternatively, Exercise 6: may be opened and the

table below may be used to specify inlet conditions.

A simple turboexpander-based demethanizer is used to recover ethane and heavier components from the gas stream as natural gas liquids (NGLs). The residue gas must be delivered at 900 psig [62 barg] with a gross ideal gas heating value of no more than 1100 BTU/ft3 [41 MJ/m3].

Add a cross-flowsheet connector to the “Dry Gas” stream exiting the TEG unit. Connect it to a new stream on the “Turboexpander” flowsheet.

The feed is completely dehydrated by a molecular sieve; model this with a Divider (under “Auxiliary Objects”) to remove 100% of water and TEG.

Use a feed split of 25% to the reboilers.

The low temperature separator (LTS) inlet stream should be set to -53°F [-47°C]. ProMax will calculate the Gas/Gas Exchanger outlet temperature required to achieve the specified LTS temperature.

The Side Reboiler duty is 5.4 MMBTU/h [1.6 MW].

Operate the Turboexpander at an outlet pressure of 250 psig [17.2 barg] and an 80% adiabatic efficiency.

The JT Valve outlet pressure is 252 psig [17.3 barg].

The bottoms liquid requirement is a C1/C2 ratio of 0.015, on a standard liquid volume basis.

The compressors have a 75% polytropic efficiency. Set the residue gas pressure to 900 psig [62 barg].

*Only use table if previous exercise not worked

Inlet Conditions

Temperature 102°F [39.1°C]

Pressure 965 psig [66.5 barg]

Flow rate 96.3 MMSCFD [107 500 Nm3/h]

Composition Mol %

H2S 3 ppm

CO2 1.55

Methane 86.44

Ethane 5.86

Propane 4.22

n-Butane 0.93

n-Pentane 0.52

n-Hexane 0.33

n-Heptane 0.15

Benzene 47 ppm

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QUESTIONS 1. What percentage of ethane and propane are recovered in the NGL stream? This can be found in the

Recoveries grouping inside of the demethanizer block.

2. How does the booster compressor pressure change compare to the expander pressure change?

3. What are the Minimum Effective Approach Temperatures for each exchanger?

4. If a kettle-type reboiler was used instead of a plate-fin exchanger, the Reboiler would use the “Pool Boiling” heat release curve type. Change the Reboiler to “Pool Boiling” and check the new Effective End Approach Temperature. Would the current process conditions be feasible if a kettle-type reboiler was used?

Exercise 7: EXCEL IMPORT/EXPORT

Goal and Information

This exercise continues from Exercise 6: Simple Turboexpander Demethanizer. Alternatively, Exercise 7: may be

opened. Use the Excel Import/Export feature to see how changing the LTS inlet temperature and turboexpander efficiency affects NGL production and required residue compression. For additional information on Excel Import/Export, see page 29.

PROCESS INFORMATION

Create an Excel workbook by clicking the “Add Excel Workbook” option in the ProMax Ribbon.

Label the first two columns “LTS Temperature” and “Turboexpander Efficiency”. Below these headers, type in -53°F [-47°C] and 80%.

Import the LTS temperature and turboexpander efficiency values from Excel. This is done by right-clicking on these properties within ProMax. In order to import values from Excel, first delete the user-defined specifications input for the LTS temperature and turboexpander efficiency inside ProMax.

Label three more columns “Compressor Power”, “NGL Flow Rate”, and “Residue Gas Composition”. Export the residue compressor power and NGL flow rate from ProMax into these columns in Excel. Make sure the selected units are correct. Export the entire Residue Gas composition (mol%) into the last column.

QUESTIONS 1. What happens to the residue compression power when the turboexpander efficiency drops to 70%?

2. What happens to the NGL flow rate when the LTS temperature increases to -45°F [-43°C]?

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Optional Extended Exercise – Simple VBA Interaction

There are many things that some simple programming can simplify, and the Microsoft Office products provide easy access to Visual Basic for Applications.

With just 2 lines of code in the current Turboexpander exercise, ProMax will automatically execute after any change in Excel.

In the excel workbook, type <Alt>+<F11> to open the VBA interface. This window can also be opened in the Developer tab by clicking the Visual Basic button

In the VBA window, go to the Tools tab and select References.

Within the available references list, select the “BR&E ProMax Type Library”.

On the left side of the VBA window, double click on “Sheet1” to write code for this Excel sheet.

Directly above the blank white page that appears, there are two dropdown menus. Set the left dropdown menu to “Worksheet” and then the right dropdown menu to “Change”. This creates a private sub where code is written that will go into effect whenever there is a change on the worksheet.

Inside the “Private Sub Worksheet_Change”, write the following two lines:

Dim PMX as new ProMax.ProMax PMX.Project.Solver.Solve (True)

Return to the Excel worksheet and change the LTS temperature to -55°F [-48°C]. ProMax will now immediately re-execute after this change has been made.

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Exercise 8: SULFUR RECOVERY UNIT

Process Background: Sulfur Recovery

If sufficient H2S is present, refineries and gas plants will require sulfur recovery units. These units take the hydrogen sulfide captured from the process and convert it to elemental sulfur for sale and transport. Claus units are the most common sulfur recovery process. This process entails burning the acid gases in a burner, then passing the gas over a specialized catalyst that converts the sulfur species into elemental sulfur. The gas is then cooled in sulfur condensers, and the liquid sulfur is removed. A typical Claus unit repeats this process several times with several catalytic beds, taking advantage of the equilibrium shift each time sulfur is removed via a sulfur condenser.

There are several variations on the typical Claus plant, including sub-dewpoint Claus beds, direct oxidation reaction beds, and partial oxidation reaction beds, any of which can be modeled in ProMax. ProMax models these reactors using Gibbs minimization with preconfigured Gibbs sets to represent each reactor in a sulfur recovery unit.

In many cases, after the acid gases have been sent through the catalytic reactor beds, the tail gas still contains too much sulfur to incinerate. The most common method of alleviating this concern is to send the tail gas through a

hydrogenation reactor, where hydrogen is added to convert most of the remaining sulfur species into hydrogen sulfide. The tail gas is then fed to an amine system for selective H2S removal. The recovered H2S is recycled back through the sulfur recovery unit, and the remaining off gas from this tail gas clean up unit can then be incinerated. This entire process can be modeled in ProMax by combining the various parts.

Additional information on optimization of sulfur recovery systems can be found within the ProMax Help or in the BRE 231: Sour Gas Processing course.

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Goal and Information

This exercise simulates a three-bed Claus sulfur recovery unit. All reactors in this exercise are Gibbs Minimization reactors, utilizing specialized Gibbs Sets that are preconfigured to select the reactive species and to add the necessary constraints.

Set the Environment to “Sulfur ASRL”

Additional components to include in the Environment: H2, SO2, CO, COS, CS2, S1 – S8

The blower increases the air pressure to 16 psig [1 barg]. The preheater then heats it to 500°F [260°C] with a ΔP = 0.5 psi [0.03 bar].

The Burner uses the “Acid Gas Burner” Gibbs Set to create COS and CS2 reaction constraints. Assume a 0% bypass fraction and ΔP = 0.

The Thermal Reaction zone (1st pass of the waste heat boiler) produces an outlet temperature of 1200°F [650°C]. This uses the “Sulfur Thermal Reaction Zone” Gibbs Set and has a pressure drop of 0.5 psi [0.03 bar]. In this set, certain components are “quenched” to keep from reacting below specified temperatures, better reflecting actual performance. COS and CS2 are excluded from reacting.

The Sulfur Redistribution block (2nd pass of the waste heat boiler) produces an outlet temperature of 700°F [370°C]. This block uses the “Sulfur Redistribution” Gibbs Set. The pressure drop is 0.5 psi [0.03 bar].

It may be easiest to specify the Claus Beds, reheats, and condensers sequentially, using the following information:

a. All sulfur condensers use the Gibbs Set “Sulfur Condenser” with a 0.5 psi [0.03 bar] pressure drop. Condensers 1 and 2 have an outlet temperature of 320°F [165°C], while condensers 3 and 4 have outlet temperatures of 300°F [160°C].

b. All reheats have a pressure drop of 0.5 psi [0.03 bar]. “Reheat 1” increases the temperature to 500°F [260°C], “Reheat 2” heat the stream to 480°F [250°C] and “Reheat 3” heats it to 430°F [220°C].

c. The Claus beds have a 5% bypass fraction and a 0.2 psi [0.01 bar] pressure drop. Claus Bed 1 uses the “GPSA Hydrolyzing Claus Bed” Gibbs set to partially destroy COS and CS2. Beds 2 and 3 use the “Claus Bed” Gibbs Set as they do not have the catalyst and temperature required for COS and CS2 destruction.

QUESTIONS 1. What is the burner outlet temperature?

2. What is the molar flow for H2S and SO2 in the tail gas?

3. How many lb/h of COS and CS2 are formed in the burner?

4. How many long tons per day (tonb/d) are produced from each condenser?

5. Plot the sulfur dew point and bed temperature vs. increment for Claus Bed 2.

6. For Condenser 1, plot liquid sulfur production vs. temperature.

7. Create a recovery in the project to represent the total sulfur recovery from all 4 sulfur condensers. Display this recovery on the flowsheet by creating a short moniker for this value.

Stream Dry Acid Gas Air

Temperature 115°F [45°C]

77°F [25°C]

Pressure 15 psig [1 barg]

1 psig [0.1 barg]

Flow rate 165 lbmol/h [75 kmol/h]

200 lbmol/h [100 kmol/h]

Composition Mol % Mol %

Hydrogen Sulfide 55 0

Carbon Dioxide 43 0

Methane 1 0

Ethane 0.6 0

Propane 0.4 0

Oxygen 0 21

Nitrogen 0 78

Water 0 1

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Optional Extended Exercise

PROCESS INFORMATION

Use a cross-flowsheet connector to send the Tail Gas on to the “Hydrogenation” flowsheet.

The fuel is methane at 30 psig [2 bar] and 77°F [25°C]. The flow rate is 1.5 lb-mol/h [1 kmol/h].

Ambient air, with an initial flow rate of 13.5 lb-mol/h [9 kmol/h], is compressed to 12 psig [1 barg] by the blower.

The Burner uses Gibbs Minimization with the “Burner” Gibbs set. Specify a pressure drop of zero.

The Hydrogenation Reactor is a Gibbs Minimization reactor and the Gibbs Set is “Sulfur Hydrogenation”. Set the pressure drop to 0.

QUESTIONS 1. What is the burner outlet temperature?

2. What is the remaining H2S content in the outlet? Is all the SO2 converted in the reactor?

FAQs on Exercise 8

The sulfur dew point within a Claus Bed can be calculated by performing an analysis inside of the bed. This is done on the Analyses tab by adding a “Vapor Pressure, Dew, Bubble Point” analysis and selecting the Dew Point Temperature. This value can then be graphed on the Plots tab.

Recoveries can be created from within the Project Viewer by right-clicking the “Recoveries” section and selecting “Add”. In this exercise, the reference stream is the Dry Gas while the Recovery streams are all four condenser liquid outlet streams. The “Atomic Basis” checkbox should be selected.

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Exercise 9: SCENARIO TOOL

Part A: Methanol Injection

Use the Scenario Tool to study the use of methanol injection to prevent hydrate formation. For additional information on how to load and use the Scenario Tool, see page 30.

PROCESS INFORMATION

Choose a Polar thermodynamic package.

Inlet conditions for the Saturated Gas are given in the table to the right.

15 lb/h [10 kg/h] methanol is added at 80°F [27°C] and 950 psig [65.5 barg].

The mixed stream is then cooled to 15°F [-10°C] by XCHG-100.

QUESTION 1. Use the Scenario Tool to vary the MeOH flowrate from 15 to 195 lb/h [10 to 100 kg/h] and compare the solid

formation temperature. If the downstream pipeline requirement states that the gas must have a solid formation temperature below 0°F [-18°C], what is the optimal methanol feed rate?

Part B: Examining Amine Flowrate Effects

Finding the optimum amine flow rate for an acid gas absorber unit includes studying several variables. Having a sweet gas concentration that is within specifications is essential, but it is not the only variable to monitor. Some other variables to consider include:

Fraction Flood – If this is an existing tower, the flooding on the trays is important to track.

Rich Loading – especially with H2S, if this is too high, there may be severe corrosion problems.

Lean and Rich Approach – help determine operational stability. If either of these is near 100%, any fluctuation of the inlet feed could cause acid gas slip, resulting in a sweet gas that is no longer within specifications.

PROCESS INFORMATION Use the Scenario Tool to track the Sweet Gas H2S Content, H2S Lean Approach, H2S Rich Approach, Fraction Flooding on stage 1, and the Total Rich Loading for a 40 wt% MDEA solution with flow rates from 160 sgpm to 280 sgpm in steps of 10 sgpm [36 m3/h to 64 m3/h in steps of 4 m3/h]. Leave the regenerator disconnected from the system for the scenario runs.

Inlet Conditions

Temperature 100°F [38°C]

Pressure 950psig [65.5 barg]

Flow 30 MMSCFD [35400 scm/h]

Composition Mole %

CO2 2

Methane 85.9

Ethane 5

Propane 5

n-Butane 1

n-Pentane 0.5

n-Hexane 0.3

n-Heptane 0.2

Water 0.1

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QUESTIONS 1. At approximately what amine flow rate does the rich approach become less than 85%?

2. At approximately what amine flow rate does the absorber reach the H2S specification of 4 ppm?

3. At approximately what amine flow rate does the rich loading reach 0.45 mol/mol?

Optional Extended Exercise: Optimum Turboexpander Pressure

A variety of factors are considered when setting the demethanizer tower pressure. Lower pressures result in colder tower temperatures which affects the C2 recovery while also affecting how much power is required to recompress the residue gas. Turboexpander efficiency will also affect both C2 recovery and residue compression power.

PROCESS INFORMATION

Use the Scenario Tool to track the demethanizer overhead temperature, C2 recovery, and residue compression power while adjusting the tower pressure (controlled by the turboexpander outlet pressure) and turboexpander efficiency. Run pressures from 225 to 275 psig [15 to 19 barg] at turboexpander efficiencies of 70% and 80%.

QUESTIONS 1. What effect does tower pressure have on C2 recovery? On recompression power?

2. What effect does turboexpander efficiency have on C2 recovery? On recompression power?

Optional Extended Exercise: Wellsite Heater Treater Conditions

Initial wellsite separation is performed to separate sales gas, hydrocarbon liquid, and produced water. In order to decrease the amount of flash emissions at the atmospheric storage tank, the hydrocarbon liquid is first sent to a heater treater. The vapors from the heater treater are compressed and re-combined with the sales gas from upstream separation. The heater treater pressure and temperature determine how much flash emissions will occur at the downstream hydrocarbon storage tank.

PROCESS INFORMATION Use the scenario tool to determine what effect changing the heater treater temperature and pressure has on BTEX emissions from the atmospheric hydrocarbon tank. Run scenarios at temperatures of 125°F, 150°F, and 175°F [50°C, 65°C, and 80°C] with pressures of 20 psig, 30 psig, and 40 psig [1.5 barg, 3 barg, and 4.5 barg]. Also track the compressor power and the heater treater energy input.

QUESTIONS 1. Why does lowering the heater treater pressure decrease BTEX emissions? How is the required compression

power affected?

2. How does increasing the heater treater temperature affect BTEX emissions?

FAQs on Exercise 9

Multiple scenarios can be made within the same Excel workbook. To create a new blank scenario, overwrite the current Scenario Name with a new name for the new scenario. Click Enter and then select “No” from the message window that appears.

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When selecting Input variables, only variables that can be user-defined within the ProMax project can be selected. These properties will be shown in bold lettering. Properties that are calculated by ProMax cannot be selected as Input variables and therefore are not bolded in the variable selection window. All variables can be Output variables regardless of whether they are user-defined or calculated values.

Scenario Tool properties can also be used as variables and are found at the bottom of the variable selection moniker tree. One Scenario Tool property that is commonly output is called Solve Status, which reports in an Excel common whether each scenario run converged or failed.

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Exercise 10: SIMPLE SPECIFIERS

Open the unsolved Exercise 10: “Simple Specifiers” file. Simple Specifiers are utilized to set one variable based on another already known variable. This automates a project so that when one variable is changed other variables will adjust accordingly. For more detailed instructions on Simple Specifiers, please see “Using Simple Specifiers in ProMax” on page 31.

Part A: Lean Amine Temperature

Add a Simple Specifier to maintain the lean amine contactor feed 10°F [5°C] above the sour gas feed temperature.

QUESTION 1. If the feed gas temperature decreases to 90°F [32°C], what is the new sweet gas H2S compositions?

Part B: Reboiler Duty

Add a Simple Specifier to set the reboiler duty based on 1 pound of steam per gallon of amine solution in circulation [0.13 kg/L solution]. To do this, attach the reboiler block energy stream to a new single-sided exchanger to represent the steam tubes side. Use 50 psig [3.5 barg] saturated steam at the inlet and saturated water at the outlet.

QUESTIONS 1. What are the sweet gas CO2 and H2S compositions?

2. What is the mass flow of steam required?

3. What is the reboiler duty?

Optional Extended Exercise: Turboexpander JT Valve Pressure

On the second flowsheet in this exercise there is a turboexpander unit. Add a Simple Specifier to maintain the pressure out of the JT valve 3 psi [0.2 bar] higher than the turboexpander outlet pressure.

QUESTIONS 1. What happens to the ethane recovery and residue compression requirements if the turboexpander outlet

pressure is dropped to 230 psig [16.5 barg]?

2. What equipment issues has this lower pressure (and thus lower temperature) potentially introduced?

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Exercise 11: SIMPLE SOLVERS

Simple Solvers adjust one variable in order to achieve a target value for another variable in a project. The user must set an initial guess so that the Simple Solver can iterate until a final solution is reached. This exercise demonstrates the use of Simple Solvers in a variety of processes previously discussed in this course. For more information on Simple Solvers, please see “Using Simple Solvers in ProMax” on page 32.

Part A: Amine Rich Loading Solver

Open the unsolved Exercise 11: “Simple Solvers” file. Add a Simple Solver to calculate the amine circulation rate needed to attain a rich amine loading equal to 0.40 mole acid gas/mole amine. Remember to assign a priority for this solver.

QUESTIONS 1. Why would a Simple Specifier not work in this situation? Why is a solver necessary?

2. What is the amine circulation rate to achieve a 0.40 rich loading?

3. What are the sweet gas CO2 and H2S compositions?

Part B: Amine Lean Loading Solver

Delete the Simple Specifier on the steam rate. Create a Simple Solver to determine the required mass flow of steam to achieve a lean loading of 0.0035 mole/mole total acid gas loading. Please review the priorities required for each solver for efficient execution of the project.

QUESTIONS 1. What are the sweet gas CO2 and H2S compositions when using both solvers?

2. What is the mass flow of steam required to attain the new lean loading?

3. What is the reboiler duty?

Optional Extended Exercise: SRU Tail Gas Ratio Solver

On the second flowsheet, add a Simple Solver to automatically adjust the air flow rate to attain an H2S/SO2 tail gas ratio of two. Make note of the original air flow rate and overall sulfur recovery prior to creating this solver.

QUESTIONS

1. What is the required air flow rate? What percentage increase of air flow was required?

2. What is the new overall sulfur recovery?

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Optional Extended Exercise: Turboexpander Exchanger Approaches

On the Turboexpander flowsheet, add Simple Solvers to maximize heat integration in the turboexpander plant. Control the LTS inlet temperature such that the minimum effective approach temperature of the gas/gas exchanger is 5°F [3°C]. Set a similar solver controlling the side reboiler duty to achieve a minimum effective approach temperature of 5°F [3°C]. A third solver is set on the inlet split percentage to the reboilers to achieve a minimum effective approach temperature in the bottom reboiler of 5°F [3°C]. Set the priority for each solver to zero.

QUESTIONS 1. Why is the priority set to be the same for each solver?

2. With these solvers in place, increase the turboexpander outlet pressure to 275 psig. Note how this affects the LTS temperature and the ethane recovery.

Optional Extended Exercise: Pipeline Network Delivery Pressure

On the Pipeline flowsheet, use a speciifier to make the “Gas 3” stream pressure equal to stream 2 and another specifier to make the “Gas 2” stream pressure equal to the “Gas 1” stream pressure. Put a Simple Solver on the “Gas 1” stream pressure to get a final delivery pressure of 500 psig [34.5 barg] to the facility.

QUESTIONS 1. Why are the Simple Specifiers necessary in this situation?

2. What is the required “Gas 1” stream pressure to achieve the desired delivery pressure?

Optional Extended Exercise: JT Skid – Methanol Injection

As discussed in Exercise 9: Scenario Tool, methanol can be injected into a process stream to prevent hydrate formation when necessary. On the JT Skid flowsheet, place a solver on the methanol mass flow rate to determine the required methanol injection rate so that stream 5 will be 10°F above solid formation. Use a step size of 10 lb/h [5 kg/h].

QUESTIONS 1. How much methanol needs to be injected?

2. OPTIONAL: Put solvers on the Gas/Gas and Gas/Liquid exchanger outlet temperature’s so that both exchangers have approach temperatures of 10°F [5°C].

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Exercise 12: USER VALUE SETS

A new user-defined variable can be specified to represent any desired value that is not defined within ProMax by default. The following exercise shows some examples of how this can be useful. For additional information on creating these user-defined variables and User Value Sets, please see User Defined Variables on page 33.

Part A: Steam Ratio

Add a user-defined variable to represent a reboiler steam ratio (pounds of steam per gallon amine in circulation). Set this ratio to 1.2 lb/gal [0.15 kg/liter]. Put a Simple Specifier on the reboiler steam rate on the MDEA flowsheet to utilize this ratio.

QUESTIONS 1. Use a “property input” stencil to display the steam ratio on the flowsheet. Adjust the ratio to 1.3 lb/gal [0.163

kg/liter] and note the change to the lean loading and Sweet Gas H2S concentration.

Part B: Cost Estimation

Some operations can estimate an operating cost based on the BTUs required. Create a user-defined variable to input this energy cost; start with a cost of $6.00/MMBtu. Add an additional user-defined variable in the same set to display the cost of running the amine reboiler based on this information.

QUESTIONS 1. What is the current operating cost of the amine reboiler ($/day), based only on the required energy? What

would the operating cost be if the energy cost was $6.50/MMBtu?

Optional Extended Exercise: Refrigeration Loop Compression Power

Create a user-defined variable to sum the total compressor horsepower requirement for the Refrigeration flowsheet. Once created, add the value as a short moniker in the project. Then add a property table to display this value on the flowsheet, based on the short moniker name.

QUESTIONS 1. What happens if an upper bound of 225 hp [168 kW] is set?

Optional Extended Exercise: Glycol Flow Rate Ratio

Glycol flow rates are typically set according to the amount of water in the feed gas. Typical ratios are between 2 and 5 gallons of glycol for each lb of water in the feed gas [15-40 L/kg]. On the dehydration flowsheet, add a user-defined variable to represent a glycol flow ratio of 2 gal/lb [15 L/kg]. Put a Simple Specifier on the glycol flow rate to utilize this ratio.

QUESTIONS 1. How are the BTEX emissions affected when this ratio is changed to 3 gal/lb [24 L/kg]?

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Exercise 13: INCINERATOR

Process Background: Incineration

As discussed previously, sulfur recovery units convert hydrogen sulfide captured from upstream processes and convert it to elemental sulfur for sale and transport. The tail gas, with small amounts of hydrogen sulfide remaining after processing, is typically sent to an incinerator. Tail gas generally has a very low heating value due to large concentrations of incombustibles so fuel is often mixed with the tail gas in order to ensure combustion. Sufficient air must also be supplied in order for enough oxygen to be present for complete combustion of hydrogen sulfide.

Goal and Information

This exercise shows how to model an incinerator to combust tail gas from a sulfur recovery unit. The effects of fuel gas and air flow rates will be analyzed and discussed.

PROCESS INFORMATION

The tail gas stream is pre-configured to represent tail gas leaving a sulfur recovery unit.

Temperature, pressure, and composition are pre-defined in the air and fuel gas streams.

To begin the exercise, set the fuel gas flow rate to 0 lbmol/h [kmol/h].

Use a Simple Specifier on the air flow rate to mix 20% excess oxygen with the combined gas. The amount of oxygen necessary for combustion can be found by performing a Combustion analysis in the combined gas stream.

The incinerator is modeled as a Gibbs Minimization reactor, using the Burner reaction set.

Set a 0 psi pressure drop in the incinerator. Set the bypass fraction to 2%.

QUESTIONS 1. What is the current incinerator outlet temperature? Why is a higher temperature desireable?

2. Fuel gas is used to achieve a sufficiently high temperature to ensure combustion. Put a Simple Solver on the fuel gas flow rate to get an incinerator outlet temperature of 1600°F [870°C]. What is the calculated fuel gas flow rate to achieve an outlet temperature of 1600°F [870°C]?

3. Change the air flow rate to run at 50% excess oxygen and re-converge the simulation. How does the required fuel gas flow rate change?

4. What does a bypass fraction of 2% represent?

5. What are the SO2 emissions from the incinerator in ton/yr?

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Exercise 14: SEPARATOR SIZING

Use the following information to size a 3-phase horizontal bucket & weir separator.

PROCESS INFORMATION

Create a hypothetical component to represent the C6+ with a molecular weight of 180 lb/lbmol and API gravity of 42.

The feed conditions and composition are shown in the attached table.

Check the “Include Separator Sizing” box inside the separator on the Process Data tab.

On the Sizing tab, select “Horizontal 3-phase Bucket & Weir” for the Vessel Type

Use a K-value of 0.5 ft/s [0.15 m/s] for V-L separation.

Use a liquid droplet diameter of 150 micron for L-L separation.

Both the light liquid and heavy liquid holdup times are 0.5 minutes and surge times are 0.25 minutes.

The light liquid low level shutdown depth is 6 inches [15 cm].

Demister pad thickness & overhead clearance are 6 inches [15 cm].

Light and heavy liquid residence times are 3 minutes.

Design temperature is 200°F [93°C] and MAWP is 435 psig [30 barg].

Corrosion allowance is 0.0625 inches [0.15 cm].

Use carbon steel A516-70 for the shell and head material of construction.

Use ellipsoidal heads.

QUESTIONS 1. What is the calculated L/D ratio?

2. In the range 1.5 < L/D < 6, what is the smallest (by mass) separator that will meet design requirements? What is the mass when the vessel is filled with water?

3. What are the shell and head thicknesses?

4. What is the settling compartment length?

5. Create an entrainment within the separator to make the heavy liquid outlet stream contain 1 vol% light liquid. Set this entrainment up on a volume per volume basis with 0.01 gal light liquid/0.99 gal heavy liquid.

6. Does this entrainment affect the sizing results?

Inlet Conditions

Temperature 155°F [68°C]

Pressure 415 psia [29 bar]

Flow Rate 58,225 lbmol/h [26 410 kmol/h]

Composition Mole %

Methane 4.9

Ethane 1.9

Propane 1.5

n-Butane 1.0

n-Pentane 0.5

Water 84.5

C6+ 5.7

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Exercise 15: DEPRESSURIZATION

In this exercise, the blowdown orifice for depressurizing a vessel will be sized to a target pressure within a certain timeframe in case of fire using API 521.

PROCESS INFORMATION

The drawn process stream represents the contents of the vessel. Operating conditions are pre-defined as described in the table.

Drag the “Depressurization Example” shape from the ProMax Property Stencil onto the flowsheet. Select the “Vessel Contents” stream from the dropdown menu.

The vent phase should be set to vapor.

Set the vessel volume to 400 ft3 [11.33 m^3].

The initial pressure and temperature are the pressure and temperature of the vessel when relieving begins. Note that this is not the normal operating pressure and temperature. For this case, set the vessel relief pressure at 688 psig [48 barg] with a relief temperature of 138°F [59°C].

Pipe inner diameter is 2 inches [6 cm]. Vent Pressure is atmospheric.

Target Pressure will be half of the relief pressure (344 psig [24 barg]). Set the target time to 15 minutes.

Check the “Use API521 for heat estimation?” box. Tank shape is “Horizontal Cylinder”. Fire-fighting is available.

Tank surroundings is set to bare. Tank elevation is 2 ft [0.6m] above grade. Specify the tank length to radius ratio as 8. Check the “Use EOS for liquid phase” selection.”

Click “Solve” at the bottom of the Depressurization window to execute the stencil.

QUESTIONS 1. What is the initial liquid volume fraction in the vessel?

2. What is the calculated orifice diameter?

3. What is the maximum venting mass flow rate?

Optional Extended Exercise – Relief Valve Sizing

PROCESS INFORMATION

On the Relief Valve Sizing Flowsheet, relief conditions for a C4/C5 mixture are specified in the stream according to the table.

Add a “Relief Valve Sizing” analysis to the C4/C5 mix stream.

Use the API520 standard and a Conventional valve.

Relief Temperature and Set Pressure are set at stream conditions

Fraction Over Pressure is 10%. Back pressure is atmospheric.

The required mass flow rate is 50,000 lb/hr [22,700 kg/h].

QUESTIONS 1. What are the calculated Effective Discharge Area and Mass Flux?

2. What is the Relieving Fluid Type? Why?

3. Set Back Pressure to 20 psig [1.4 barg] and switch to Balanced Bellows. What is the new Effective Discharge Area? What is the Back Pressure Correction Factor?

Vessel Contents

Temperature 100°F [38°C]

Pressure 560 psig [38.6 barg]

Composition Mole %

C1 26

C2 30

C3 15

iC4 10

nC4 15

C5 4

C4/C5 Mix

Temperature 170°F [76.7°C]

Pressure 75 psig [5.2 barg]

Flow Rate 50,000 lb/hr [22 700 kg/h]

nC4 70 mol%

nC5 30 mol%

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Exercise 16: SHELL & TUBE HEAT EXCHANGER RATING

Use the shell & tube exchanger specification sheet provided to rate the Lean/Rich Exchanger in an amine unit.

QUESTIONS 1. What is the area available in the exchanger for heat transfer?

2. Display the percent over-design on the flowsheet.

Optional Extended Exercise: Fraction Over Design Solver

Add a Simple Solver to the shell & tube outlet temperature going into the regenerator. Set this solver to achieve a fraction over design of 10%. Remember to assign the best priority to the solver for the most efficient execution.

QUESTIONS 1. What is the new temperature going into the regenerator?

FAQs on Exercise 16

Tube service is set to Demand for this exchanger since the rich amine stream (2) that is being heated runs through the tubes. This is due to the corrosive nature of the rich amine.

Fouling resistance can be user-specified for side A and side B of the exchanger. Go to the Connections tab to determine which fluid is on side A and which is on side B.

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69

ProMax Additional Exercises

Exercise 17: REFRIGERATION LOOP

Use the Propagation Terminal in ProMax to determine the required refrigerant flow.

PROCESS INFORMATION

Use 100% propane as the refrigerant.

Compress to 250 psia {17.25 bar], then cool to 120°F {48°C].

Expand to 35 psia {2.4 bar] across the valve.

Use 10 MMBtu/h [2.93 MW] for the Q-Load stream in this example.

Inlet Conditions

Temperature 80°F [27°C]

Pressure 300 psia [20.7 bar]

Flow Rate 33 sgpm [125 lpm]

Composition Mole % Propane 99.973 Methyl Mercaptan 0.027

QUESTIONS 1. What is the required flow rate of propane, and the compressor HP?

Exercise 18: ETHYLENE GLYCOL INJECTION

Prevent solids when processing a 0.7 gravity gas using EG.

PROCESS INFORMATION

Circulate 500 lb/h [225 kg/h] EG solution.

Operate the LTS at -5°F [-20.5°C].

Heat the LTS liquids temperature to 30°F [0°C] so emulsions forming at low temperature will separate in the oil/glycol separator.

Operate the oil/glycol separator at 265 psia [18.3 bar].

Regenerate the EG solution to 80 wt% using an atmospheric regenerator. A reflux ratio of 0.15 is sufficient.

Sales gas temperature leaving the gas/gas exchanger is 100°F [38°C].

Inlet Conditions Temperature 110°F [43°C] Pressure 1000 psia [69 bar] Flow Rate 25 MMSCFD

[29,500 sm^3/h]

Composition Mole% Methane 86.05 Ethane 6.06 Propane 3.39 i-Butane 0.84 n-Butane 1.36 n-Pentane 2.30 100% water saturated

QUESTIONS 1. What is the solids formation temperature of the low temperature separator feed? 2. What is the water dew point (or freeze out temperature) of the sales gas?

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Exercise 19: MIXED AMINES

Sweet Gas with < 0.5 mol% CO2 and 100 ppm (mol) H2S.

PROCESS INFORMATION

Use 100 sgpm [375 lpm] of 30 wt% MDEA / 15 wt% DEA .

Absorber: 21 real trays, ∆P = 4 psi [0.25 bar] , D=3.5 ft [1.1 m], weir height = 3 in [5 cm], tray spacing = 2 ft [0.6 m].

Stripper: 20 real trays, operating P=24.4 psia [1.6 bar], ∆P = 5 psi [0.3 bar], condenser = 120°F [49°C], reboiler = 5.5 MMBtu/h [1.6 MW].

Flash tank operates at 80 psia [5.5 bar].

QUESTIONS 1. What is the rich amine loading? 2. What is the makeup rate of water, MDEA, and DEA? 3. What is the liquid residence time on a tray in the absorber?

Inlet Conditions Temperature 100°F [38°C] Pressure 500 psia [35 bar] Flow Rate 25 MMSCFD

[29,500 sm^3/h]

Composition Mole % H2S 0.1 CO2 3.3 Methane 72.4 Ethane 13.3 Propane 7.5 n-Butane 2.7 n-Hexane 0.7 100% water saturated

Exercise 20: ACTIVATED MDEA FOR ACID GAS REMOVAL

Compare sweetening results using activated MDEA with the results using basic MDEA.

PROCESS INFORMATION

Process set-up is identical to Exercise 3:Simple MDEA Sweetening Unit; the unsolved version of this exercise is identical to the solved version of Exercise 3:

Add piperazine as a component in the Environment, then modify the Make-up/Blowdown block to maintain 3% piperazine in addition to the 40% MDEA.

QUESTIONS 1. How does the H2S and CO2 absorption compare? What caused the results to shift this way?

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Exercise 21: PHYSICAL SOLVENT ACID GAS REMOVAL

Achieve a Sweet Gas with 3% CO2 using a DEPG.

PROCESS INFORMATION

The flash tanks should operate at 250 psia, 25 psia and 5 psia [17.5 bar, 1.75 bar, and 0.34 bar] .

The first flash vapor is compressed and mixed with the inlet .

Circulate 325 sgpm [1230 lpm] of DEPG (make-up pure DEPG).

Chill the lean solvent down to 45°F [7°C] before entering the contactor.

QUESTION 1. Try various chiller temperatures to see how this affects the

treated gas and acid gas compositions.

Inlet Conditions Temperature 95°F [35°F] Pressure 950 psia [65.5 bar] Flow Rate 9 MMSCFD

[10.600 sm^3/h]

Composition Mole% Methane 65 CO2 35 100% water saturated

Exercise 22: MERCAPTAN REMOVAL FROM LPG USING NAOH

Simulate mercaptan removal using a caustic solution.

PROCESS INFORMATION

Use 1 sgpm [4 lpm] of 10 wt% NaOH solution; assume there is residual methyl mercaptan in the caustic of 0.01 wt%.

The caustic solution should be cooled to 80°F [27°C].

Specify a two stage LLE column.

Inlet Conditions Temperature 80°F [27°C] Pressure 300 psia [20.7 bar] Flow Rate 33 sgpm [125 lpm] Composition Mole %

Propane 99.973 Methyl Mercaptan 0.027

QUESTIONS 1. What percent recovery of CH3S is achieved in the absorber?

2. What is the liquid viscosity of the lean caustic solution feeding the column?

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Exercise 23: CO2 REMOVAL USING NAOH

Simulate CO2 removal using a caustic solution.

PROCESS INFORMATION

Use 5 sgpm [19 lpm] of 7 wt% NaOH solution.

Select the Caustic property package.

QUESTIONS 1. Using the ionic info analysis information, determine how

much Na2CO3 will be formed. 2. What is the CO2 content of the fuel gas in ppm? 3. What is the respective CO2 contents when the NaOH

circulation is decreased to 4 sgpm [15 lpm], then 3 sgpm [11 lpm]?

4. What is the liquid viscosity of the rich caustic solution?

Inlet Conditions Temperature 100°F [38°C] Pressure 165 psia [11.4 bar] Flow Rate 15 MMSCFD

[17700 sm^3/h] Composition Mole % CO2 0.1 Nitrogen 10 Hydrogen 11 Methane 40 Ethylene 17 Ethane 16 Propylene 0.8 Propane 3.9

Exercise 24: MEA FLUE GAS CO2 CAPTURE

Reduce CO2 to <1% mol in an inlet flue gas stream.

PROCESS INFORMATION

The gas is first treated in a 3-stage “Ideal Stage” caustic SO2 scrubber (10 sgpm [38 lpm] of 10% wt NaOH].

A 4-stage TSWEET Kinetics absorber uses 2 ft. [0.6 m] spacing and 2 in. [5 cm] weirs.

Circulate 1300 sgpm [295 lpm] of 28.2 wt% MEA; cool to 125°F [52°C].

Strip with 0.8 lb/gal [0.1 kg/L] of 60 psia [4.1 bar] saturated steam, and a 120°F [49°C] condenser. The regenerator operates at 10 psig [0.7 barg].

Inlet Conditions Temperature 125°F [52°C] Pressure 16 psia [1.1 bar] Flow Rate 50 MMSCFD

[59,000 sm^3/h] Composition Mole % H2O 11.8 CO2 12.8 O2 5.6 N2 69.8 SO2 0.01

QUESTIONS 1. Why is the scrubber required? 2. Why does the cooler not need to keep the amine 10°F [5°C] above the feed gas temperature?

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Exercise 25: FRACTIONATION TRAIN

Fractionate the liquids from a demethanizer into ethane, propane, butanes, and a C5+ condensate.

PROCESS INFORMATION

Deethanizer

a. An initial guess is required for column convergence; use 99% ethane recovery in the top.

b. The column operates at 300 psia [20.7 bar] with a ∆P=7psi [0.5 bar].

c. Ethane product exits at a 65°F [18.3C] condenser temperature.

d. Specify a 0.04 C2/C3 ratio in the bottoms product.

Depropanizer

a. The exchanger cools the feed to 180°F [82°C]. b. The column operates at 205 psia [14.1 bar] with a ∆P=

3psi [0.25 bar]. c. Use a reflux ratio of 2. d. 99.9% of the C3 is to be recovered in the vapor. e. Use an initial guess of 98% i-C4 recovery in the

bottoms.

Debutanizer

a. The condenser is sub-cooled to 160°F [71°C]. b. Column pressure is 150 psia [10.3 bar] with a ∆P= 5 psi

[0.4 bar]. c. Recover 99.9 mol% n-C4 in the overhead product. d. Use a boil-up ratio of 4. e. Use an initial guess of 99.9 mol% recovery of i-c5 in

the bottoms.

Butane Splitter

a. The column operates at 135 psia [9.3 bar] with a ∆P= 20psi [1.5 bar].

b. Use a total condenser with the i-Butane product sub-cooled to 70°F [21°C].

c. Use a boil-up ratio of 11.5. d. The bottoms product purity specification is 97.5 mol%

n-C4.

Inlet Conditions Temperature 80°F

[27°C] Pressure 500 psia

[34.5 bar] Flow Rate 2400 lb-mol/h

[1080 kg-mol/h]

Composition Mole % Methane 0.63 Ethane 49.00 Propane 27.00 i-Butane 4.15 n-Butane 7.60 i-Pentane 2.20 n -Pentane 2.14 n-Hexane 3.80 n-Heptane 0.60 Benzene 0.12 Toluene 0.17 Ethylbenzene 0.009 p-Xylene 0.13 Nitrogen 0.051 CO2 2.40

QUESTIONS 1. What is the ethane recovery in the deethanizer?

2. What is the propane recovery in the depropanizer?

3. What is the RVP of the C5+ split?

4. What is the temperature difference between stages 2 and 60 of the butane splitter?

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Exercise 26: ENVIRONMENTAL BTEX CALCULATIONS

Build the following flowsheet which represents a field production and separation facility.

PROCESS INFORMATION

In “Project Options”, set Atmospheric Pressure to 11.3 psia [0.78 bar].

Use the Peng-Robinson property package in the Environment. Add the components listed in the inlet composition and H2O.

Water rate is 0.5 sgpm [2 lpm].

The inlet mix goes through a choke valve and line heater and then enters the high pressure separator at 875 psig [60.3 bar] and 95°F [35°C]. Set the line heater pressure drop to 0.

The sample line contains material that will be sampled for extended GC analysis.

The liquids leave the condensate tank at 0 psig [0 bar]. Do not set pressure drop in the condensate tank.

Inlet HC Conditions Temperature 115°F [46°C] Pressure 1000 psig [69 barg] Flow Rate 1.04 MMSCFD

[1225 sm^3/h]

Inlet HC Composition Mole % Methane 90.2 Ethane 6.3 Propane 1.2 i-Butane 0.06 n-Butane 0.08 n-Pentane 0.13 n-Hexane 0.15 n-Heptane 0.5 n-Octane 0.2 n-Nonane 0.17 n-Decane 0.73 Benzene 0.03 Toluene 0.13 Ethylbenzene 0.012 m-Xylene 0.137

QUESTIONS 1. What is the molecular weight of the inlet HC feed?

2. How much heat in BTU/h must be supplied to the line heater?

3. What mole fraction of the HP Flash feed left as a vapor?

4. How many barrels/day of liquid condensate are produced?

5. What is the API gravity of the condensate?

6. How many tons/yr of BTEX leave with the condensate tank emissions? Use the “Sum Components” ProMax Property Stencil.

7. Prepare a Phase Envelope Analysis of the Sales Gas. What are the critical temperature and pressure?

8. Select the “Hydrate Curve” option in the phase envelope from the previous question. At what temperature will hydrates form if this stream remains at 875 psig [60.3 bar]?

9. What are the Reid Vapor Pressure (RVP) and True Vapor Pressure (TVP) of the condensate?

10. Using a combustion analysis, determine the rate of oxygen required (lbmol/h) to completely combust the emissions stream.

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Exercise 27: SIMPLE SOUR WATER STRIPPER

This unit is used to remove several contaminants from utility water before sending it to waste water treatment. Here, we will simulate a sour water stripper with a thermosyphon and an overhead condenser.

PROCESS INFORMATION

The pump outlet pressure is 40 psig [3.8 bar]. Use 65% pump efficiency.

The Sour Water enters the Stripper at 190°F [90°C].

The stripper has 7 ideal stages, and should be an Equilibrium column type.

The top stage is 8 psig [1.5 bar] and the column has a 1 psi [0.06 bar] pressure change.

The Condenser outlet temperature is 185 °F [93°C].

For stripping, a thermosyphon is used to heat and return 70% of the bottoms. This stream is 15% vaporized through the exchanger.

The Air Cooler lowers the stripped sour water temperature to 110°F [43°C].

The column may require a pump-around duty estimate. Give this initial guess for the thermosyphon loop as a “Pump-around Estimate” column specification.

After setting up the simulation, insert a Property Table to display the temperatures, pressures, flow rates, and compositions of the Sour Water, Stripped Water, Stripper Overheads streams.

QUESTIONS 1. Determine the pump’s head and required horsepower.

2. What are the end-point approach temperature, and Effective UA in the Feed Effluent Exchanger?

3. What is the Stripper bottoms temperature?

4. What is the recovery of H2S and NH3 in the Stripper Overhead?

5. What is the pH of the Sour Water from Tankage and the cooled Stripped Sour Water?

6. The pressure drop in the Stripper Overheads is to be maintained below 5 psi/100 ft of horizontal length. Using schedule 40 pipe, what diameter is required? What is the actual ∆P and velocity?

7. What is the critical point for the Stripper Overhead?

Inlet Conditions

Temperature 95°F [35°C]

Pressure 0.3psig [1.05 bar]

Flow Rate 545 sgpm [120 m3/h]

Composition Mass %

NH3 0.55 H2S 1.2 Phenol 0.1 HCN 0.001 H2O 98.149

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Exercise 28: AIR COOLER RATING

Using the heat exchanger specification sheet on page 77, rate the fin fan heat exchanger used to cool the lean amine before entering the amine contactor.

PROCESS INFORMATION

This will require creating a second side to the exchanger by connecting a second single-sided exchanger to the first via a common energy stream.

“Air” is not a component in ProMax, and must be created from its constituent components – at a minimum nitrogen and oxygen, and additionally water, argon, carbon dioxide and other lesser components, if desired.

The rating option is available once the exchangers have been connected with a common energy stream (or if the single-sided air cooler icon is replaced with a double-sided exchanger). This option is found in the Project Viewer of the heat exchanger under the Process Data Tab at the bottom. Check the box for “Enable Rating”, and select the correct exchanger type from the drop-down list. Once this box is checked, a new tab appears in the Project Viewer for “Rating”.

QUESTIONS 1. What is the calculated pressure drop for the process stream?

2. How can the heat exchanger rating be exported to an .hexr file?

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Additional Help & Troubleshooting 8.1. BASIC SPECIFICATIONS FOR PROMAX BLOCKS

Each block within ProMax gives the user some freedom to specify what is occurring around that block. There are many possibilities of what can be specified within and around each type of block, not all of which are covered here. The following is a list of the most common types of specifications:

Inlet Streams The user must fully specify inlet streams. This generally means providing these 4 pieces of information: Temperature, Pressure, Flow Rate (molar, mass, or volumetric flow), and composition.

Pumps/Compressors/Expanders: An efficiency and outlet pressure are the most common specifications.

Heat Exchangers: A pressure drop is required within every heat exchanger. For multi-sided exchangers a pressure drop is required for each side. Along with the pressure drop, a single or double-sided heat exchanger allows for one temperature-related specification to be set. Most commonly one of the outlet temperatures is set but in some cases a duty or Minimum End Approach Temperature may be set instead.

Separator: A pressure drop or outlet pressure is required. If an energy stream is attached to a separator (such as with a condenser) then an outlet temperature can also be set.

Valves: An outlet pressure (most common) or pressure drop must be specified.

Columns: Columns are allowed 1 specification for every energy source to the column (Reboiler, Condenser, etc.). The specifications the user chooses to use will vary greatly depending on the process. For a complete list of available specifications, see page 13. Regardless of configuration, all columns need a user-specified pressure profile.

Process Recycles: Process recycles allow the user to estimate what is happening at a particular point in the process to allow ProMax to iterate towards the final solution. For process recycle blocks, the recycle outlet stream must be completely user-specified just like an inlet stream (temperature, pressure, flow rate, composition).

Q (Energy) Recycles: Energy recycles require the user to estimate how much energy is being recycled. This energy estimate is user-specified within the block itself.

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8.2. GENERAL GUIDELINES FOR DIAGNOSING ERRORS

If a block is bright red, it means the block is missing one or more connections. Check the

Connections tab to determine which connections need to be made before the block can be

solved.

If a stream is bright red, it means the stream is missing a specification.

Check to make sure that all inlet streams going to an unsolved block are green, meaning they are converged. A

block will not solve if any of its inlet streams are not solved.

Click the “Warnings” button in the ProMax Ribbon to bring up a list of all the errors and warnings currently in

the ProMax project. The Warnings list should always be checked, even if the simulation is fully converged.

The Message Log records information about convergence each time the user clicks to Execute. When

troubleshooting, make sure to look at the most recent information at the bottom of the Message Log by right-

clicking in the log and selecting “Page End”.

Most “Errors” prevent a simulation from converging. “Warnings” appear when the simulation has converged

but there are certain parts of the simulation that are outside normal operations or normal simulation practices.

Thus, the user can determine whether or not a warning needs to be addressed.

Interpreting ProMax monikers in Message Log error messages

Every object & property within ProMax has a “moniker” that acts as an identifier for that object (similar to a web address). Error messages include the object moniker where the error occurred. Each moniker follows this pattern:

ProMax:ProMax!Project every moniker begins with this reference meaning it is an object found in a ProMax project

Flowsheets!Gas Processing the moniker mentions which flowsheet it is looking at (a flowsheet named “Gas Processing” in this case).

PStreams!16 this portion mentions which object the moniker is referring to (a process stream named “16” in this case). PStream stands for process stream. QStream refers to energy stream, and Block refers to any block.

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8.3. COMMON ERRORS & WARNINGS

Generic Block Errors

This error means that a block is overspecified. Common causes of over-specification:

Exchanger: Outlet temperatures specified for both outlets of an exchanger OR both an outlet temperature and Minimum End Approach Temperature specified.

Pump: Outlet temperature and pressure specified, along with an efficiency or power inside the pump

Columns

Inside a column, at the very bottom of the Project Viewer, it will say “Under Specified” when there are degrees of freedom available to the column that have not been used.

This error occurs when the pressure profile has not been configured within the tower. This means that on the Stages grouping within the Process Data tab either a pressure change or top/bottom stage pressures need to be set.

OR

OR

OR

A column turns yellow (meaning it is approximating a solution).

These errors mean the column could not find a solution. First, verify that all the column inlet streams and column specifications are correct. If these are all correct, go to the Convergence tab within the column and try changing the Enthalpy Model, then the Inner Loop Model. Sometimes using a different model can find a solution when the default did not.

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If none of these combinations work, click the “Delete Last Solution” button and try again to execute the column. Adding a K Damping factor (0-10) can help with oscillation issues. Checking the “Boston-Sullivan Kb” option or changing the MESH Method can also help with convergence. Lastly, the max number of iterations can be increased by going to the “Solver” grouping under the Convergence tab.

This warning occurs when an amine absorber is run as the incorrect column type. On the Process Data tab in the Column grouping, make sure “TSWEET Kinetics” is selected for the Ideal Stage Column Type.

This warning occurs when an amine stripper is run as the incorrect column type. On the Process Data tab in the Column grouping, make sure “TSWEET Stripper” is selected for the Ideal Stage Column Type.

OR

All columns are required to have vapor entering on the bottom stage of the column. Similarly, all columns must have liquid feeding into the top stage of the column.

This error message means a duty estimate is required for a column pumparound loop. If duty is added to a pumparound by a heat exchanger (other than the condenser) or pump, an estimate may be required for the total pumparound duty amount. This estimate can be made within the column by adding a “Pump-around Estimate” specification. Estimate a negative duty if energy is being removed from the loop.

Heat Exchangers

Always check inside the exchanger to make sure a Pressure Drop is specified. If it is a double-sided exchanger, then it will require a Pressure Drop on both sides of the exchanger.

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This error message means there is a temperature cross in the heat exchanger, indicating that the specified heat transfer is thermodynamically impossible. While the heat exchanger (and model) will converge, any attempt to rate the exchanger will fail. Adjust any duty or outlet temperature specification until there is no longer a negative approach temperature for the exchanger.

Pumps

This error occurs when ProMax calculates a pump efficiency greater than 100%. This usually occurs when the user specifies an outlet temperature from the pump. Generally, it is recommended that the user not specify the temperature coming out of a pump but instead specify an efficiency inside the pump which will allow ProMax to calculate the outlet temperature.

Recycles

This error message means that the recycle block was not able to converge to a solution after performing the set maximum number of iterations. The first thing to do is verify that there is a reasonable estimate in the recycle block outlet stream. The maximum number of iterations can be increased inside the Recycle block under the Solver grouping on the Converge tab.

Simple Solvers

This error message indicates that a variable written into the Solver/Specifier equation is undefined. This means either a) the variable has not been added to the Measured/Independent Variable list or b) the name written in the equation does not match the name given to the Measured/Independent Variable. Make sure the variable is listed and that the names match, keeping in mind that names are case-sensitive and no spaces are allowed in the name.

This error message indicates that a Solver initial guess has not been set. Inside the solver, make sure an initial estimate has been put into the Calculated Value cell. ProMax will adjust this initial guess until it reaches a solution.

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Solver/Recycle Priorities When there is more than one solver and/or recycle in a simulation, priorities tell ProMax the order in which to solve the different solvers/recycles. ProMax will solve from the highest priority on down. Poor priority order can lead to much longer convergence times and even prevent a simulation from solving. Consider the following:

Give higher priorities to solvers that come first in sequence. Example: solvers/recycles on an amine unit should solve before (and therefore have higher priorities than) solvers/recycles on a downstream dehydration unit.

Nested, inner loops should be solved before outer loops. Example: solvers within a recycle loop should solve before the loop recycle block.

The exact number value of a priority is unimportant; it is only the comparison of priorities from highest to lowest that matters. Example: if a recycle has a priority of 10 and a solver has a priority higher than 10 (11, 20, 100, etc.), ProMax will solve the solver and then the recycle.

A list of solvers/recycles in a project, including their priorities, is found in the Solver Summary within the Project Viewer.

Streams

This error means that either the temperature or pressure being calculated for the specified stream is outside the maximum/minimum allowable values in ProMax. The most common cause is a duty within an exchanger that is impossibly high for the given stream’s flow rate.

OR

These warnings appear for any stream that is near or below a temperature where hydrates could form. Similar warning messages appear for ice and dry ice formation. This means that solids could potentially form at this part of the process and the user should consider running at higher temperatures, removing water (or CO2 for dry ice) from the system, or injecting a hydrate inhibitor such as methanol or ethylene glycol.

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8.4. WEB TUTORIALS

At www.bre.com, an ever-expanding library of web tutorials is available to demonstrate common ProMax applications. These videos include explanations of each block in ProMax, how-to videos on different ProMax tools, discussions on commonly simulated processes, and much more.

Some pertinent videos for those wanting to learn the basics of ProMax are listed below.

ProMax Tools

Simple Specifier

ProMax Solver

Scenario Tool Basics

Creating User Values – Ambient Temperature Example

Single Oils

Common Processes

Amine Sweetening Initial Design

Pipeline Model

Separator Sizing

Additional Tips

What’s New in ProMax 4.0

Streams & Blocks Tips

Column Convergence Tips

Selecting Components in a ProMax Environment

Selecting a Property Package in a ProMax Environment

Solver Summary Table

Project Options

BRE 101 Exercise Demonstrations

BRE 101 - Exercise 1 (Simple Gas Plant Part 1)

BRE 101 - Exercise 1 (Simple Gas Plant Part 2)

BRE 101 - Exercise 1 (Simple Gas Plant Questions)

BRE 101 - Exercise 3 (Simple MDEA Sweetening Part 1)

BRE 101 - Exercise 3 (Simple MDEA Sweetening Part 2)

BRE 101 - Exercise 4 (Export/Append)

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8.5. VISIO HOTKEYS

Standard Microsoft hotkeys are available within any ProMax project. In addition, a user also has the ability to create custom hotkeys through VBA programming.

Below is a summary of commonly used Visio hotkeys (based on Visio 2016):

Ctrl + A Select All

Ctrl + D Duplicate Selected Shape (creates a new, blank shape)

Ctrl + C

Ctrl + V

Copy and Paste Selected Shape(s)

(user-defined properties in a stream will be copied along with the stream but internal block info will not be copied with the block)

Ctrl + H Flip Shape Horizontal

Ctrl + J Flip Shape Vertical

Ctrl + S Save File

Ctrl + 3 Toggle to/from Connector Mode

Ctrl + 2 Toggle to/from Text Mode

Ctrl + X Delete Selected Shape(s)

Ctrl + L Rotate Selected Shape Counterclockwise

Ctrl + R Rotate Selected Shape Clockwise

Ctrl + Click Select Multiple Shapes

Ctrl + Wheel Zoom In / Out

Shift + Wheel Scroll Flowsheet Right / Left

Shift + Arrow Nudge Selected Object Right/Left/Up/Down