3 Hysys Training Distillation Tutorials 3 4 5

8/10/2019 3 Hysys Training Distillation Tutorials 3 4 5

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Steady State Simulation Using Aspen Hysys


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Designing Distillation System Using Hysys

Objective:

Become comfortable and familiar with various

distillation column models in Hysys and use of sizing

module


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Distillation Models

Four models are available which can be used to model

and design industrial fractionation system

Distillation Column

Model with Condenser and Reboiler in-built

Used for conventional solvent separation

Refluxed Absorber

Model with Condenser and no Reboiler


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Distillation Model (Continue.)

Absorber

Model without Condenser and Reboiler

Used for absorber or stripper

Reboiled Absorber

Model with Reboiler and no Condenser

Used to model reboiled stripping or absorber


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Tutorial 3 De-Methaniser

0.00270.0001C8

0.00470.0002C7

0.00370.0003C6

0.01020.0020N-C5

0.01470.0036i-C50.01970.0085N-C4

0.02040.0112i-C4

0.07500.0706C3

0.11760.1921C2

0.72270.7041C1

0.00290.0048CO2

0.00570.0025N2

Mole FractionMole fractionComponents

215 kmol/hr1620 kmol/hrFlowrate

2290 kPa2275 kPaPressure

-85 deg C-95 deg CTemperature

Feed 2Feed1Name

Build a flowsheet in Hysys to model De-Methaniser


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Tutorial 3 De-Methaniser Study

Study Feed Streams 2 Feed Streams contain Methane and heavier vapours

Also contain traces of non condensables N2 and CO2

Feed conditions low temp and high pressure

Decide Thermodynamic System

Which are key components?

What are boiling points of methane and ethane

Configure streams in simulation and study their state (liq/vap)

Can methane be separated by flashing to lower pressure? To

study using a simple flash Need distillation column


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De-Methaniser To Decide Column inputs

To Decide Column Inputs

What type of column? Fractionator / Stripper / Rectifier?

No need of condenser why?

Number of theoratical stages based on difficulty of separation

Column top pressure and pressure drop per stage

Feed Locations

Feed-1 at top stage to provide reflux

Feed-2 at stage 4

Configure column specs -

Reboiler Duty

Distillate Rate

Provide Temperature Estimates


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Tutorial 3 De-Methaniser Column flowsheet details

kmol/hr1338Distillate Rate

kPa2310Bottom Stage Pressure

kPa2275Top Stage Pressure

10Number of Stages

Main TS

kJ/hr2.1e+06Heat Flow

Ex Duty

4Feed 2

2Ex Duty

1Feed 1

Feed StageStream

Property : Peng Robonson

27 CBottom

-68 CTop

Temperature Estimates


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Tutorial 3 De-Methaniser Answer Fol lowings..

What is mole fraction of methane in overhead?

:______________

Add design specification to get 95 % (mole) ofmethane in overhead. You have to add Column

Component Fraction spec from Specs page and

deactivate distillate flowrate. What is mole fraction of methane in overhead?

:______________

What is flowrate of overhead product? :______________


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Tutorial 4 De-Ethaniser

Add pump to transfer bottom product of De-Methaniser to De-

Ethaniser column with following data

2790 kPaDC2 Feed Pressure

WorksheetP=100-HPEnergy

DC2 FeedOutlet

DC1 BtmInlet

Connections

EnterIn This cell


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Tutorial 4 De-Ethaniser (Continue)

De-Ethaniser is modeled using Distillation column with

following details

DC2 Cond QCondenser Duty

DC2 BtmBottom Liquid Outlet

DC2 Reb QReboiler Duty

DC2 Feed / 6Feed stream/Stage

DC2 OvhdOverhead Vapour ProductDC2 DistOverhead Liquid Product

14No. of stages

DC2Name

Connections EnterIn This cell


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2.5 (Molar)Reflux Ratio

0 kmol/hrDistillate Rate

320 kmol/hrOverhead Vapour Product

95 CReboiler

Specifications

2792 kPaReboiler

Temperature Estimates

-4 CCondenser

35 kPaCondenser Delta P

2725 kPaCondenser

Pressures

EnterIn This cell

Answer this

What is flowrate of C2 and C3 in DC2 Btm?

C2 _____________, C3_______________, Ratio C2/C3 ________________


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Add design specification to maintain ratio of C2/C3 to 0.01,

deactivating Ovhd Vap Rate. Select Column Component

Ratio as specification type with following information

PropaneDenominator

EthaneNumerator

0.01Spec Value

LiquidPhase

Mole FractionFlow Basis

ReboilerStage

C2/C3Name

EnterIn This Cell

What is the flowrate of DC2 Ovhd ? : _____________________


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Tutorial 5 Methanol Water Separation

Feed:63.2 wt% Water

36.8 wt% Methanol

Total flow = 120,000 lb/hr

Pressure 18 psia

Saturated liquid

Desired Purity of Products: 99.95 wt% methanol in the distillate

99.90 wt% water in the bottoms


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Tutorial 5 Methanol Water Separator Study

Study Feed and Required Column Specs Decide Thermodynamic System

Any Azeotrope between Methanol Water?

What are boiling points of Methanol and Water?

What type of column? Fractionator / Stripper / Rectifier?

Number of theoratical stages based on difficulty of separation

Column top pressure and pressure drop per stage

Feed Location

Configure column specs -

Distillate Rate Reflux Ratio


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Tutorial 5 Methanol Water Separation

Part A:

Perform a rating calculation of a Methanol tower using thefollowing data:

Use the NRTL Property Method

Feed:63.2 wt% Water36.8 wt% MethanolTotal flow = 120,000 lb/hrPressure 18 psiaSaturated liquid

Column specification:38 trays (40 stages)Feed tray = 23 (stage 24)Total condenserTop stage pressure = 16.1 psiaPressure drop per stage = 0.1 psi

Distillate flowrate = 1245 lbmol/hrMolar reflux ratio = 1.3


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Part B:

Set up design specifications within the column so the following

two objectives are met:

99.95 wt% methanol in the distillate

99.90 wt% water in the bottoms

What are condenser and reboiler duty?

Condenser Duty :_________

Reboiler Duty :___________

What is reflux ratio ? :______________________

Tutorial 5 Methanol Water Separation (Continue)


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Part C:

Perform the same design calculation after specifying

a 60% Murphree efficiency for each tray. How do these efficiencies affect the condenser and

reboiler duties of the column?

Part D: Perform a tray sizing calculation for the entire column,

given that Bubble Cap trays are used.

What is column diameter required for this separation ? : _____________

Tutorial 5 Methanol Water Separation (Continue)

3 Hysys Training Distillation Tutorials 3 4 5

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