CBB 3024PROCESS PLANT DESIGN

Lecturer : Assoc. Prof. Dr. Mohamed Ibrahim Abdul Mutalib

Dr Mohanad El-Harbawi

4 Credit-Hour Core Course

Lecture Time : Mon 10 am – 12 noon ; Mon 1 – 3 pm: Thurs 11 am – 1 pm ; Fri 8 – 10 am

Location : LT D2 ; 21-01-04 17-02-06 21-02-07

Semester May 2011

PROGRAMME OUTCOMES – UTP CHEMICAL ENGINEERING

1 Acquire and apply knowledge of basic sciences and engineering fundamentals

2 Acquire and apply Chemical Engineering principles and in-depth technical knowledge

3 Ability to design, optimize and operate processes

4 Undertake problem identification, formulation and solution by considering the concept of sustainable development

5 Comprehend social, cultural, global and environmental responsibilities of a professional engineer, and the need for sustainable development

6 Communicate effectively in a professional context

7 Exhibit professional and ethical responsibilities

8 Demonstrate leadership, business acumen and entrepreneurship

9 Demonstrate the capability to undertake lifelong learning

COURSE OUTCOMES – CHEMICAL PLANT DESIGN

K S A

3   PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO3 PO9 PO7

CO1Integrate knowledge from previous chemical engineering courses in designing a chemical process system

x x x           x    

CO2Apply conceptual process design and synthesis tools in designing a chemical process system

x x x x         x    

CO3 Apply a systematic approach or method to design a chemical process system

   x x   x x   x   x

K – KnowledgeS – SkillA – Attitude

Course Content, Delivery & Assessment

Lec. No.

Topic Assessment Lecturer

1-2

3-4

Introduction to Plant Design and Economics (Approaches and Stages of Process Design)

General Plant Consideration (Plant Layout/Utility System)Quiz 1

Dr Ibrahim

Dr Ibrahim

5-8 Synthesis of Reactor Separation System(Fundamentals and Selection of Reaction System & Separation System)

Assign 1Test 1

Dr Ibrahim

9-12 Synthesis of Reactor Separation System(Fundamentals and Selection of Reaction System & Separation System)

Assign 1Test 1

Dr Ibrahim

13-16 Synthesis of Reactor Separation System(Process Recycle and Distillation Sequencing)

Assign 1Test 1

Dr Ibrahim

17-20 Heat Integration (Composite Curve & Heat Recovery Pinch, Problem Table Algorithm)

Assign 2Test 1

Dr Ibrahim

21-24 Heat Integration (Grand Composite Curve & Multiple Utilities) Assign 2Test 1

Dr Ibrahim

25-28 Heat Integration (HEN Design) Assign 2Test 1

Dr Ibrahim

Lec. No.

Topic Assessment Lecturer

29-32 Process Flowsheeting (Flowsheet Synthesis & Simulation, Model Formulation, Solution Strategies)

Test 2 Dr Mohanad

33-36 Economics of Chemical Plants Quiz 2 Dr Ibrahim

37-40 Equipment Design & Specification (Material Transfer & Handling, Mass Transfer Equipment)

Assign 3Test 2

Dr Mohanad

41-44 Equipment Design & Specification (Mass Transfer & Reactor Equipment)

Assign 3Test 2

Dr Mohanad

45-48 Equipment Design & Specification (Pressure Vessel Design) Assign 3Test 2

Dr Mohanad

49-52 Environmental Studies & Consideration – Effluent Treatment, Waste Minimisation and Life Cycle Analysis

Quiz 3 Dr Mohanad

53-56 Plant Wide Control (Material & Quality Control, Pairing of Variables in MIMOS, Typical Unit Operation and Control Strategies)

Quiz 4 Dr Ibrahim

Assessment : Quizzes – 4 (5 %) Assignments - 3 (5%) Projects - 1 (10%)Tests - 2 (20%) Final Exam - 1 (60%)

The purpose of engineering is to create material wealth – Douglas, Conceptual Design of Chemical Processes 1988.

How to do so ?

Raw Materials+ Other Feeds

EnergyIn

CHEMICAL PROCESS Products + Wastes

Energy Out

WHAT CAN YOU SAY ABOUT THE CHEMICAL PROCESS ?

Lecture 1. Introduction to Plant Design and Economics

In a chemical process, the transformation of raw materials into desired products usually cannot be achieved in a single step. Instead, the overall transformation is broken down into a number of steps that provide intermediate transformations. (Robin Smith, Chemical Process Design 1995)

The goal of the engineer is to design and produce artifacts and systems that are beneficial to mankind – Biegler, Grossman & Westerberg, Systematic Methods of Chemical Process Design 1997.

Raw Materials+ Other Feeds

Energy

CHEMICAL PROCESS

Products + Wastes

Energy

SO, A NUMBER OF PROCESSING STEPS MADE UP THE CHEMICAL PROCESS.

QUESTIONS?

- WHAT SORT OF PROCESSINGS ARE LOCATED IN THE CHEMICAL PROCESS? - HOW DO WE SEQUENCE THE PROCESSING STEPS?- TO WHAT EXTEND CAN WE EXPECT EACH OF THE PROCESSING STEP TO PERFORM AND WHAT FEATURES ARE REQUIRED? - HOW MUCH ENERGY IS REQUIRED AND HOW MUCH IS PRODUCED?- HOW MUCH FEEDS DO WE NEED AND HOW MUCH PRODUCTS ARE PRODUCED?- HOW MUCH WASTES ARE GENERATED?- HOW MUCH PROFIT COULD BE DERIVED?

HOW DO WE ADDRESS THIS?

Concept Design for Chemical Process

Raw Materials+ Other Feeds

Energy

CHEMICAL PROCESS

Products + Wastes

Energy

PROCESS PLANT DESIGN IS THE NAME OF THE GAME HERE !

LITTLE OR LIMITEDINFORMATIONS AREAVAILABLE

BEFORE COMING UP WITH A COMPLETE PROCESS

But so many possibilitiesor solutions !

Perhaps, the major features that distinguishes design problems from other types of engineering problems is that they are under defined; i.e., only a very small fraction of the information needed to define a design problem is available from the problem statement. (Douglas, Conceptual Design of Chemical Processes 1988)

Once the process concept has been designed which produces process flowsheet,

the equipment design then has to be performed…..

Distillation

The equipment design comprises of ;

1. Performance/Capacity Rating or Sizing

2. Vessel Mechanical Design

Equipments’ Dimensions – diameter & height

No. of stages for contact

Heat Transfer Area Needed

Wall thickness

Support DesignPipe fittings & Reinforcement

Internal Design

The process safety and control strategy has to be devised;

1. Process Safety

2. Process Control Strategy

- Material Control

- Product Control

Overall Plant and Equipment ….

- Hazard and Operability Study (HAZOP)

- Risk Assessment

HAZOP study

Risk Assessment Matrix

And Waste Treatment/Minimisation need to also be addressed…

1. Waste Treatment (conventional)

2. Waste Minimisation (sustainability)

- Suitable ‘end of pipe’ treatment on the effluent (gases & liquids)

- Adjusting processes to minimise the generation of wasteREACTOR

SEPARATION & RECYCLE SYSTEM

HEAT EXCHANGERNETWORK

UTILITIES

In finalising the process and equipment design, several stages of economic analysis could be conducted …

First step;EP 1 = Revenue – Cost of Raw Material

Second Step (after mass balance developed)EP 2 = Revenue – Cost of Raw Material - Utility

Third Step (after equipments designed)EP 3 = Revenue – Cost of Raw Material – Utility – Annualised Cost of Equipment

The economics analysis continues with other costs (manpower, insurance etc) ….

with profitability analysis conducted at the end to assess project viability ……

Pay back time,Return on InvestmentInternal Rate of Return

Finally …..

1. ADDRESS THE INDIVIDUAL PROCESS/TRANSFORMATION STEP

2. ADDRESS THE REQUIRED INTERCONNECTION BETWEEN THE STEPS

FEED REACTOR

CW

STEAM

PRODUCT 1

PRODUCT 2

RECYCLE

Lecture 2. Approaches and Stages of Process Plant Design

In the first stage, conceptual process design has to be conducted.In general conceptual process design has to address two major activities ….

……….and the target is to create the best possible feasible flowsheet for the process.

THIS IS WHAT YOU WANT AT THE END OF THE STAGE !

WHAT OTHER INFORMATIONS SHOULD BE AVAILABLE IN A FLOWSHEET ?

AND HOW DO YOU GET SUCH INFORMATION ?

FEED REACTOR

CW

STEAM

PRODUCT 1

PRODUCT 2

RECYCLE

Str1 Str2 Str3 Str4 Str5 Str6 Str7 Str8 Str9F

T

P

x

H

DEFINITION OF A FLOWSHEET.FLOWSHEET IS A DIAGRAMMATIC REPRESENTATION OF THE PROCESS STEPS AND ITS INTERCONNECTIONS.

A SYSTEMATIC APPROACH OR METHOD IS REQUIRED

However, as much as we would like to have a systematic approach or method, we must also recognised that process design is an art !

If we reflect on the nature of process synthesis and analysis, …. , we recognize that process design actually is an art, i.e., creative process. (Douglas, Conceptual Design of Chemical Processes 1988)

The approach or method should be able to help in addressing these questions …

Why is the unit operation selected ? How are the unit operations connected ?

What are the utilities required and approximate amount ? How will it be supplied to the process unit operations ?

What wastes will be generated?

1. ADDRESS THE INDIVIDUAL PROCESS/TRANSFORMATION STEP

2. ADDRESS THE REQUIRED INTERCONNECTION BETWEEN THE STEPS

FEED REACTOR

CW

STEAM

PRODUCT 1

PRODUCT 2

RECYCLE

FLOWSHEET

Now, what criteria should be adopted besides economics during the design activities?

MINIMISE COST

MINIMISE ENERGY CONSUMPTION

MINIMISE WASTES GENERATION

..... BUT HOW TO OPTIMISE ?

HIGH SAFETY & INTEGRITY

GOOD OPERATIONAL ASPECTS

QUANTIFIABLE FACTOR !

NON - QUANTIFIABLE FACTOR !

VERSUS

FEED REACTOR

CW

STEAM

PRODUCT 1

PRODUCT 2

RECYCLE

Consider back the flowsheet !

OPTIMISING THE INTERCONNECTIONSBETWEEN THE UNITS/STEPS IN THE PROCESS

?

MANY POSSIBLE CONNECTIONS WHICH LEADTO DIFFERENT STRUCTURES OF FLOWSHEETTHUS DIFFERENT ECONOMIC IMPACT EVEN TO THEEXTENT OF THE INDIVIDUAL UNIT ITSELF!

DIS-CONTINUOUS FUNCTION

STRUCTURAL OPTIMISATION

OPTIMISING A SINGLE UNIT/STEP IN THE PROCESS

EG. DISTILLATION COLUMN

TOTALCOST

RR

RR --> ENERGY

RR --> CAPITAL

CONTINUOUS FUNCTION

PARAMETER OPTIMISATION

How do we tackle them ?

Consider the approaches/methods which have been introduced to deal with such complex optimisation ?

MIXED INTEGER LINEAR/NON-LINEAR PROGRAMMING

MATHEMATICAL METHOD

USE A MATHEMATICAL PROGRAMMING METHOD TOSOLVE AND GIVE SOLUTION FOR THE PROCESS.SIMULTANEOUS SOLUTION OF ALL THE SYSTEM.

CONCEPT IS BASED ON"CREATING AND OPTIMISING A REDUCIBLE STRUCTURE"

DECISION ARE BASED ON SOLELY MATHEMATICAL OPTIMISATION CRITERIA

Grossman I. E, Comp. Chem. Eng., 9: 463, 1985

Biegler, Grossman & Westerberg, SystematicMethod of Chemical Process Design 1997

ONION MODEL

HEURISTIC METHOD

USE A SEQUENTIAL/HIERARCHICAL METHODACCORDING TO FOLLOWING SEQUENCE ;1. REACTOR2. SEPARATION AND RECYCLE SYSTEM3. HEAT EXCHANGER NETWORK4. UTILITIES

CONCEPT IS BASED ON"BUILDING AN IRREDUCIBLE STRUCTURE"

DECISION ARE BASED ON ENGINEERING GUIDELINESESTABLISHED AND MATHEMATICAL OPTIMISATION

Smith R.,Chemical Process Design 1995

HIERARCHICAL APPROACH

USE A SEQUENTIAL/HIERARCHICAL METHODACCORDING TO FOLLOWING SEQUENCE ;1. BATCH VS CONTINUOUS2. INPUT-OUTPUT STRUCTURE OF THE FLOWSHEET3. RECYCLE STRUCTURE OF THE FLOWSHEET4. GENERAL STRUCTURE OF SEPARATION SYSTEM5. HEAT EXCHANGER NETWORK Douglas.,Conceptual Design of Chemical Process 1988

HEURISTIC METHOD – The Onion Model

REACTOR

SEPARATION & RECYCLE SYSTEM

HEAT EXCHANGERNETWORK

UTILITIES

- FOLLOWS ONION LOGIC

Design starts from the centre ( heart of process ) which is the reactor.At each layer, decision has to be made to complete the design requirement for the stage. As such, many best local optimal decisions are made since the whole picture is incomplete. Unit/Equipment is added only if it is economically justified based on the current available information. This keeps the process (structure) irreducible and features which are technically/economically redundant are not included.

What do you see are the advantages and disadvantages of this method ?

Advantages Disadvantages

WHAT DO YOU NOTICE ONTHE STATEMENT CONTAIN WITHINTHE SHADED BOX ?

Compare these statementsto the onion model !

REACTOR

SEPARATION & RECYCLE SYSTEM

HEAT EXCHANGERNETWORK

UTILITIES

HEURISTIC METHOD – The Hierarchical Approach

The conceptual design is performed based on 5 different stages. The approach is somewhatdifferent by tackling the 5 different level that are classified differently. The 5 levels are ;

Level 1 Decision : Batch vs Continuous

Level 2 Decision : Fixing the Input-Output Structure

Level 3 Decision : Determining the Recycle Structure for the ProcessLevel 4 Decision : Determining the Separation System

Level 5 Decision : Determining the Heat Exchanger Network

At each level except level 1, alternatives have to be generated and assessed to see its economic and operational potential. Some level of process design has to be conducted on the units/process placed at every stages.

Semester July 2004

MATHEMATICAL METHOD – The Mixed Integer Linear/Nonlinear Programming

What are the advantages and disadvantages of this method ?

Advantages Disadvantages

- CREATION OF SUPERSTRUCTURE/HYPERSTRUCTURE

A major (super) structure is created which embedded within it all feasibleprocess (including its operations) and all feasible interconnections thatare candidates for an optimal design. The method is completely automatedand depends only on the computer programming to solve it. The design problem is formulated into sets of mathematical equations which has to besolved by the mathematical programming. Started off with many redundant features, the programming optimise and reduce the process (structure) to an optimal solution.

other processalternatives

From the conceptual process design, a flowsheet is generated for the process. The next stage would then be to address the equipment design …

FEED REACTOR

CW

STEAM

PRODUCT 1

PRODUCT 2

RECYCLE

Heat Exchanger

Type of Exchanger (Plate / Shell & Tube)Heat Transfer CoefficientHeat Transfer AreaPressure DropExchanger Configuration

Reactor

Type of ReactorReaction KineticsReaction SelectivityReactor SizingReactor Temperature & Pressure

No of stagesReflux RatioFeed LocationVapour/Liquid LoadingColumn SizingInternalsColumn Temperature & Pressure

Distillation

There are established methods for performing the design of these equipments ….

Heat Exchanger

Rating calculation that will enable the sizing of the heat exchanger to be done

Kern’s method Reactor

Reactor

From the kinetics obtained from experiment, sizing of reactor could be done based on residence time.

Distillation

No of stages calculation versus reflux ratio could be made and the feed location determined.Results are then simulated in rigorous simulation model for actual design involving capacity calculation for internals.

Fenske, Gilliland & Underwood

Heat Exchanger

Reactor

Distillation

Given that each of the equipment will normally involved vessel operated at various pressure and temperature, the design of the pressure vessel has to be conducted. The design is to be done according to standards…..

Pressure Vessel Dimension Shell ThicknessFlanges Connection & ReinforcementSupport type and DesignCorrosion AllowanceWelding specification

American Society of Mechanical Engineers (ASME)Boiler and Pressure Vessel Code.ASME Boiler and Pressure Vessel Code (BPVC) is a standard that provides rules for the design, fabrication, and inspection of boilers and pressure vessels. It is reviewed every three years.

Health, Safety and Environment aspects are increasingly gaining attention in view of their importance. Therefore the design of process plant has to take into account of the HSE particularly the safety and environment aspects where it has to be integrated with the design activities ….

Inherent SafetyRemove or attenuate conditions that could lead to the 3 incidents such as high P and T …..

Hazard Analysis

FIRE EXPLOSION TOXIC RELEASE

Auto Ignition temp.Flammability LimitsFlash PointsMinimum Oxygen concentration

Flammable liquids are more dangerous than flammable gas

Chemical Energy vs Physical EnergyDeflagration vs detonationConfined vs Unconfined Explosions (VCE)

Time weighed exposureShort term ExposureCeiling ExposureLC50 & LD50DOW Index

HAZOP

Hazard and Operability Study.

Environment

Health, Safety and Environment aspects are increasingly gaining attention in view of their importance. Therefore the design of process plant has to take into account of the HSE particularly the safety and environment aspects where it has to be integrated with the design activities ….

Environment

Waste Minimisation(Clean Process Technology)

Waste Treatment

ReactorIncrease conversion if selectivity is not an issueProduct removal for reversible reaction favoring productSet T & P to improve selectivity

DistillationRecycling waste stream to suppress by product reactionFeed purificationEliminate use of extraneous material for separation (entrainer)

Waste stream recoveryImprove heat recovery

Air EffluentParticulate, CO2, CO, SOx, NoxGravity Settlers, Inertial Collectors, Scribbers, Filters, Electrostatic precipitators, catalytic reaction etc.

Water EffluentMembrane, Adsorption, Absorption, thermal oxidation, biological treatment, membrane separation etc.

Finally …..

You will develop the construction details for a process plant ….