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of ‘Black-box' Models in Power Plant Flowsheets

Yidong Lang & Lorenz T. Biegler

Department of Chemical Engineering

Carnegie Mellon University

Energy System Initiative

March 7, 2010

Optimization and Integration

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Outline   Motivation   Development of ROM   Wrapped yROM for flowsheet   Integration of ROM into Flowsheet in GAMS   Optimization and Closed loop evaluation   Converting yROM into USER3 model   Integrating the USER3 with IGCC in AspenPlus

for further Optimization with EO mode

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Concepts of APECS: Co-Simulation with Aspen Plus and Fluent

CFD Model

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Road map from CFD model to “Black box” model

Flowsheet of IGCC in APECS with Aspen

Plus and Fluent accommodating CFD

Model

Extracted CFD

model

Developed ROM

Developed USER3 Model According to the protocols in Aspen Plus

Equations of ROM inserted part of

IGCC flowsheet in GAMS Flowsheet of IGCC in Aspen Plus with

replacement of USER3 of ROM which can be optimized with EO

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ROM Development for CFD Model

Ref: Lang et al., Reduced Order Model Based on Principal Component Analysis for Process Simulation and Optimization†, Energy & Fuels 2009, 23, 1695–1706

xROM PCA ROM

yROM For Iterative process simulation and optimization

Display fields of states after convergence Cases of

CFD Model

ROM is a remedy to overcome CPU time prohibited of CFD model in iterative computing of co-simulated flowsheet simulation and optimization

1.  Determine operation domain, Experimental design (LHS) 2.  Run Fluent cases according to the results of Experimental design

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split

The predicted effect of inputs on outlet temperature given by yROM shows reasonable reliability

Development and Validation of ROM for Gasifier

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Interface

Coal

Water

Oxyg.

s41 s81

s82

s83

s84

s85

s86

s87

s88

s89

Gasifier

GFpost

Splitter

Mixer 1

Mixer 2

Wrapping yROM of Gasifier as a section of flowsheet

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AIR

FUEL

LP CONS . MP

CONS . HP CONS .

CW

DW

High Pressure ( HP ) Header

Vacuum Header

Condensate Header

Medium Pressure ( MP ) Header

Low Pressure ( LP ) Header

Deaerator

HRSG

Gas Turbine

S 1 S 58

S 2

S 3

S 59

S 4

S 60

S 61

S 5

S 6 S 7

S 8

S 9

S 15 S 20

S 16 S 12

S 11 S 17

S 10 S 37 S 38

S 34 S 35 S 36

S 41 S 46

S 43

S 42

S 45

S 40

S 39 S 47 S 54

Gas

ifier

wat

er

Coa

l

O2

Integration yROM of Gasifier and Steam Cycle

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Minimizing Objective Function Subject to

Power Demand (Net Electricity): 500 MW

Objective Function Add. Constr Optimal solutions

u1 u2 u3

1 Heating Value of Syngas No 84.6928 34.9266 84.8813

2 Coal Feed flowrate No 70.3411 25.2085 75.2154

3 Heating Value of Syngas Tout >1660 Tout < 1670

84.6928 34.9266 82.716198

4 Coal Feed flowrate Tout >1660 Tout < 1670

70.3411 25.2085 75.912813

Optimal Solution

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H2S H2O H2 CH4 CO2 CO Temp(K)

Loop test (1)

ROM 0.013172 0.305403 0.011566 0.025022 0.067842 0.552102 1709.19

Fluent 0.013149 0.305228 0.011611 0.024865 0.069569 0.550176 1712.65

Error(%) 0.17 0.06 0.38 0.63 2.48 0.35 0.20

Loop test (2)

ROM 0.015087 0.207855 0.017510 0.031057 0.065993 0.635727 1644.08

Fluent 0.015114 0.206340 0.017904 0.030502 0.065742 0.638125 1627.54

Error(%) 0.18 0.73 2.20 1.82 0.38 0.38 1.02

Loop test (3)

ROM 0.013277 0.304384 0.011538 0.027482 0.061432 0.557007 1670.00

Fluent 0.013280 0.302956 0.011573 0.028183 0.065889 0.552833 1667.49

Error(%) 0.02 0.47 0.30 2.49 6.76 0.76 0.15

Loop test (4)

ROM 0.015042 0.206258 0.017836 0.029846 0.073121 0.631096 1660.00

Fluent 0.015602 0.211528 0.016875 0.031671 0.063249 0.635083 1657.04

Error(%) 0.13 2.49 5.69 5.76 15.61 0.63 0.18

Results of closed loop test for yROM

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Closed Loop (1) for xROM

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Closed Loop (2) for xROM

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Closed Loop (3) for xROM

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Closed Loop (4) for xROM

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Converting yROM into USER3 model in Aspen Plus

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IGCC flowsheet and integration of replaced CFD model

Water shift

TSA and CO2 compression

Gas-Combustor-Turbine

Steam cycle

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Conclusions

  The concept of APECS is extended to process optimization by replacing CFD model with its PCA ROM in IGCC flowsheet

  ROM for gasifier is developed and validated   ‘Closed loop’ tests in GAMS show that validation from converged

Fluent case is encouraging.   Conversion from yROM into USER3 model is successfully

implemented and can be integrated with an existing IGCC flowsheet

  We are now aiming at EO mode of the simulator, it is potentially possible to used novel NLP solver like Ipopt in process optimization for IGCC

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Future Work

  ROM of Gas turbine combustor will be developed following the procedures of PCA ROM

  Convert its yROM into USER3 in Aspen Plus and integrate with IGCC

  Implement optimization with integrated two ‘Black-box’es using EO and open solver in Aspen Plus