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Tutorial 10 : OptimizationAspen Team_XIII Generation

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Why should we learn Optimization?

We can use optimization to maximizeor minimize a user-specified objectivefunction b mani ulatin decision

variables (feed stream, block input, orother input variables).

Commonly, optimization will becombined with constraint.

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Optimization : Step by Step..

Run Simulation

Determine the constraints

Determine the objective functionand selected constraints

Specify the manipulated variable

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To create a constraint problem :

1 From the Data menu, point to ModelAnalysis Tools, then Constraint.

n e ons ra n ec anager,click New.

3 In the Create New ID dialog box,

enter an ID (or accept the default ID)and click OK.

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To create an optimization problem:

1 From the Data menu, point to ModelAnalysis Tools, then Optimization.

n e p m za on ec anager,click New.

3 In the Create New ID dialog box,

enter an ID (or accept the default ID)and click OK.

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The recommended procedure forcreating an optimization problem is:

1 Start with a simulation (instead of starting withoptimization). There are a number of reasons for thisapproach:- It is easier to detect flowsheet errors in a simulation.

- ou can e erm ne reasona e spec ca ons.- You can determine a reasonable range of decisionvariables.

- You can get a good estimate for the tear streams.2 Perform sensitivity analysis before optimization, to find

appropriate decision variables and their ranges.3 Evaluate the solution using sensitivity analysis, to find

out if the optimum is broad or narrow.

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Case Study :

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Case Study :

Benzene & toluene can be produced fromcrude oil in refinery.

,

are separate and enter the tower.

Use optimization to get maximum product

revenue

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Case Study :

Total crude oil feed 25736 kg/hr atcondition 77.4 C and 6.2 bar

propana = 0,05388i-butana = 0,14808n-butana = 0,29493

metil butana = 0,13301n-pentana = 0,12368n-heptana = 0,23114benzena = 0,00941toluena = 0,00587

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Tower

Number of stage 33

Pcond 6.52 bar

Pressure drop column 0.24

Reflux ratio 1.8

Distilate to feed ratio 0.49806

Vapor feed stage 13

Liquid feed stage 20

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First Step : Run Simulation

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First Step : Run Simulation

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First Step : Run Simulation

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First Step : Run Simulation

Run Simulation!!!

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Second Step : Determine Constraint

1. Define (thats easy for you)2. Spec

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Third Step : Determine Optimization

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Third Step : Determine Optimization

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Third Step : Determine Optimization

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Third Step : Determine Optimization

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Third Step : Determine Optimization

Run!!

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Thanks for your attention..