马后炮化工技术论坛_Consortium of Reaction-Separation Prosess （Aspen Dynamics）

8/13/2019 _Consortium of Reaction-Separation Prosess Aspen Dynamics

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Consortiumof

Reaction Se aration

Prosess

Speaker:JianKai Cheng()

DeptofChem.Eng.

NationalTaiwanUniversity


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Introduction

Dynamic Data in Aspen Plus Running Simulation in Aspen Dynamics

Distillation with RadFrac

Reactors Tasks

Process Control


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AspenDynamicsisatoolintheAspenEngineeringSuit

fordynamic

simulation

of

flowsheets

AspenPlus:SteadyState,BasisforAspenDynamics

simulations

AspenDynamics:Running

off

the

shelf

models

based

ib

AspenPlusflowsheet


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Build steady state

Prepare flowsheet for

Add dynamic data

Export simulation

Dynamics

,

disturbance


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What happens if operating conditions change?


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1. Create the simulation flowsheet in Aspen Plus

Properties, components, stream, blocks,

2. Enter the dynamic information in Aspen Plus

.

4. We have a dynamic model for our flowsheet

Change control system

Etc


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IntroductiontoAspenDynamics


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Describethedatarequiredtocreateadynamic

simulationinput

from

Aspen

Plus

flowsheet


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Clickdynamictoolbuttontoactivatedynamicdata

forms


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Dataisrequiredtocalculatethefollowing:

Vesselgeometry

Vesselinitialfillage


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Vesseltype

Instantaneous Defaulttyperequirednoinputvesselgeometry.

Vertical

Horizontal Vesselgeometry

Headtype

Diameter Length


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Export

Creates and saves the Aspen Dynamics Problem file (*.dynf)* .

required for the properties calculations

Send to

Exports then automatically starts Aspen Dynamic and loads theexported problem files

Runid#.dynf

Runid#.appdf


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Thefollowingobjectsareexported:

Components Properties

StreamandBlock(Supportedmodelonly)

Thefollowing

objects

are

not

exported:

S ecification

Calculator


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ere are wo ypes o ynam c s mu a ons:

Flow-driven Useful for a first approach of dynamic behavior of the

processes

Good for liquid processes Pressure driven

Flowrate is controlled by pressure differences

More realistic, the system must be setup, pumps and.


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Alwaysanalyzethemessagewhileexportingthe

simulationas

they

are

really

important

Warning:Somethingyoushouldreallycheck!

Example:

Flashvessel

full

of

liquid

Phasetype

(Fatal)Error:Thesimulationcannotbeexportedor

usedwithout

corrective

action

Pressuredrop


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FatalError

Useof

any

Aspen

Plus

feature,

which

is

not

support

in

Aspendynamics

Anyresults,whichareinconsistentwithadynamic

s mu at on,e.g.,pro emw t a rac pressurepro e

Error

Ablockthatisnotsupport

Note:Ifaflowsheet includesanunsupportedblock,itwillstillbe

block

Anythingwhich

could

cause

aproblem

in

the

dynamic

simulation e. . ne ativeorzero ressuredro invalves


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Thefollowingobjectsareexported

Component Properties

Streamandblock

Thefollowing

objects

are

not

exported

S ecification

Calculatorblocks


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Workshop:

AddingDynamic

Data

Buildthesteadystateflowsheet


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RunningSimulationinAspenDynamics



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Reviewthebasicconceptsinrunningthesimulation

Explainhow

to

run

and

pause

Showhowtodisplaytheresults


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Displaythecontentofthesimulation

ComponentList:

Components

and

physical

property

Globals:Optionsforthesimulation

Flowsheet:

Blocks

and

streams

on

the

flowsheet

L rar es:Li raryo mo e s

Diagnostics:Informationonresultion


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Selectsthetypeofsimulation

AspenDynamics

is

typically

used

with

Dynamic

and

Initializationrunmode

Initialization run:

Solvesequations

of

the

system

at

time

0

to

find

the

valuesofthe freevariables

Dynamicrun:

Theintegrates,stepbystep,equationsofthesystem


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To start or continue the simulation (Run button)

To run ste -b -ste

To pause the simulation (Pause button)

To go back to a time 0 (Re-start button)

To go back to a timed snapshot (Rewind button)


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Communication

interval

Time units for

Pause Time


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Selectstheparametersfor

numericalmethods

Importsettingonintegrator

sheet

InitialIntegration

step

Defaultvaluesare

setting


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Fixed: Specifythevalueofthevariablefor

thecalculation

Free: ValueiscalculatedbyAspenPlus

time0

OriginalvaluesarefromtheAspenPlussimulation

You

can

save

new

starting

points

in

current

resultssectionsorinsnapshots.


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1. Click the new form button

2. Select the option, click OK3. Open a table/plot

4. Click the name of the variable

5. Hold down the left mouse button to drag it anddrop it on the form

6. Right Click to change its

its properties7. The table/plot is defined

in Flowsheet folder


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Workshop:

RunningAspen

Dynamics

Explorethemainstepsonhowtorunasimulation:

Experimentwithpredefinedplotsandtables

Rewind,Restart


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DistillationwithRadFrac



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OverviewofRadFraccapabilities

Dynamicform

in

Aspen

Plus

ModelandSpecificationsofexportedto:

Reviewsome

specific

details

of

Aspen

Dynamics

assum tions

CompleteworkshopadRadFrac


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Dynamic RadFrac may be used in the same applications

as steady-state model

n ynam c mo e. a rac mo e s e pressure rop

across each stage due to the head of liquid and vapor

Stage hydraulics are also modeled

Reaction-Dist Reaction type: equilibrium reactions are not

supported User reaction type us supported


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Heattransferoption

CondenserReboiler

Sizeandinitialcondition

Refluxdrum

Sum

Decanter

calculationforthestages


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on ensers an re o er o ups are typ ca surge vo ume.

Heuristics: 5 min residence time for condensers and reboilers

-

= 3LEx. Overhead vapor rate=5577 lb/hr and 29 lb/ft

= =35577 5min 2 32ft

29 60minV

hr lb

Liquid Volume Fraction = 0.5


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Aspectratio(L/D)rangesfrom1to4generally

Atypical

value

of

2is

often

used

2 2 3

= = =Volume 4 4 2


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Simple Trays: Uses simple correlation for trays

Simple Packing: Uses simple correlation forpacking

rating or packing rating

becomes too low


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To complete form, you need to select the option update

pressure profile in the tray rating or packing rating


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Example showing default controllers for a simple

column

Pressure Control ler

Level Controlle

W k h


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Workshop:

DistillationColumn

HeterogeneousAzeotropic Distillation

1. Build

steady

state

design

in

Aspen

Plus2. Adddynamicdata

3. Trydynamicsimulation

4. Change

condition

of

the

process


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Reactors



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PresentthereactormodelssupportedbyAspen

Dynamics RCSTR

RPlug

Workshop


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Plugflowisdiscretized intoanumberoffixedsize

elements Supportliquid,vapor,liquidvaporandliquidliquid

vaporphaseoptions

Onlykinetic

reactions

are

supported

reactions(forwardandreverse)

fluidismodeled


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Aspendynamicsusesaonedimensional,firstorder

finite

difference

scheme

to

solve

the

partial

equationsfortheRPlug reactor.Thefinitesizeof

eachelementmaycauseacertainamounterror

Reduce

the

error

by

increasing

then

number

of

finite

differenceelementsfromthedefaultvalueof10

RPlug Report/ProfilesheetinAspenPlus

Workshop:


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Workshop:

RCSTRand

RPlug

ComparedifferenttransferoptionsinRCTRand

RPlug


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Tasks



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Exposethepurposeoftasks

Explainsyntax

of

task

instructions

Workshop


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A task is a set of instructions that define a

sequence of actions taking place during adynamic simulation

Change the value of some variables, write message

You can create as many tasks as you like

The tasks can be

Event-driven tasks: triggered by a predetermined

simulation time, a logical becoming true

Callable Tasks: called from another task


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You need to end statements with a semi colon (;)

Syntax to access a variable within a: Blocks: Blocks(block name).

Ex: Block(C130).Level

Stream: Stream s(block name). Ex: Stram(FEED).FmR

Compile task: Short cut-Function key F8


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Tocreateaflowsheet task:

1. Double

click

Add

Task2. Definetaskname

3. Entertaskinsructions

4. Compile

5. Activatetaskifeventdriven

callable taskinactive

error taskactive


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Syntax

TASK TaskName (ParameterList)TaskStatement ;

END

CallCALL TaskName (ParameterList)


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Syntax

as ame t me

TaskStatement ;

END

time:apostive real

value

representing

asimulation

me


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Syntax

TASK TaskName RUNS ONCE WHEN conditionTaskStatement ;

END

TASK TaskName RUNS WHEN condition

TaskStatement ;

END

Condition:

time==value(synonymofRUNSATvalue)

expression1>,=,


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Assignment:Tochangethevalueofafixedvariable

Unitsof

measure

can

be

specified

between

braces{}

variable: value {unit};

Ramp:To

increase/decrease

avariable

to

target

va uew nearors nes ape rampo spec e

duration

RAMP (variable: value, finalvalue, duration);

SRAMP (variable: value, finalvalue, duration);


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WAITFOR:Suspendstheexecutionofthetaskuntil

conditionismet.Executionwillcontinuefromthe

nextstatement

WAIT FOR condition

numberoftimeunitsrepresentedbyRealExpression.

WAIT duration;


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RESTARTAFTER:Endstheexecutionofatask.Thetaskwill

thenrestartafterthenumberoftimeunits representedby

.

statementafterstartcondition.

.

restartwhen

the

condition

is

true.

Execution

will

continue

fromthefirststatementafterstartcondition.

RESTART:Endstheexecutionofatask.Thetaskwillrestart.

Executionwillcontinuefromthefirststatementafterstart

condition.


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Learn about the Aspen Dynamics process

control models

Become familiar with the PIDincr controller

-

Pressure

Temperature


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Dynamicslibrarycontrolmodels


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ControlSignal

Streamtypetoconnectcontrollertothe

otherobjects


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Toobtaingoodresultsthatcanbetransferredtoa

realcontrolsystem,itisimportantthatyou

accuratelymodeltheloopdynamics

Itisparticularlyimportanttomodellagsanddead

timesinthecontrolloop


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Foranysensor,t eresponseo measurementisnotinstantaneous.Itis

morerealistictoincludemeasurementlags.

number time (minutes) type

_____________________________________________________

Temperature Liquid 2 0.5 First order lag

Gas 3 1 First order lagComposition GC 1 3-10 Dead time

_____________________________________________________


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Cascade mode

Percent toggles

display b/w process

Manual mode switch

switch

Configuration form

Plot form

Auto mode switchTunin controller

parameters

PIDincrBlockConfiguration:


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Tuningand

Ranges

[ ]rang OP

[ ]range PV

=


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Direct:

Whenthemeasuredvariableincrease,themanipulated

variableshouldbe increased

Indirect:

Whenthemeasuredvariableincrease,themanipulated

variableshould

be

decreased


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se t ecurrentva ueso t emeasure var a esandmanipulatedvariabletoinitializecontroller

ThevaluefortheoperatorSPchangestothevalueofthe

The

value

for

the

OP

changes

to

the

value

of

the

manipulatedvariable

Processvariableandoutputrangeschangedto0to2timesthevalue

xcep on:

orva ve

pos on,

erange

sspec e

o

an

Typically,youusethisonlyonce,whenyoucreate

AutoGeneratedControllers


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(FlowDriven

Mode)

Controller When Measured Manipulated

ar a e

Pressure apor o up

ismodeled

ressure n

vessel

aporout et

moleflow

rate

Level Liquidholdup

ismodeled Liquidlevel

Liquidoutlet

massflowrate

AutoGeneratedControllers


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(PressureDriven

Mode)

During the export, it checks for valves connected

on liquid and vapor outlets

If a valve block is present, the controller will

manipulated the valve position

Pressure control with vapor outlet

Liquid level with liquid outlet

,

created so that you can select another appropriate

variable to mani ulate in As en D namics


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Remark: 1. Generate sustained oscillation in a controlled manner.

2. Ku=4h/a and Pu are readily available.

3. Set the controller using Ziegler-Nichols type of tuning.


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First order plus dead time model

(FOPDT)

0.5

Ds s

K e e

1 2 1G s

s s= =

+ +

=max(1.7D,0.2 )

2 DK K

+=

I

2

/ 2D

= +

I

?

?

cK

=

=

Worksho :


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ControlSystem

of

Heterogeneous

Azeotropic Distillation

SettemperatureController

Set

concentration

Controller Tunecontrollerparameters


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http://support.aspentech.com/

, 2006-SteadyStateto

Dynamic.


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1. Luyben,W.L.;Tyreus,B.D.;Luyben,M.L.Plantwide ProcessControl,McGrawHill,NewYork,1999.

. uy en,

.

. an w e ynam c mu a ors n em caandProcessingandControl,MarcelDekker:NewYork,2002.

. , . .

Simulation,WILEY

Interscience:

New

York,

2006.


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马后炮化工技术论坛_Consortium of Reaction-Separation Prosess （Aspen Dynamics）