VOC Reduction by VOC Reduction by Dynamic Condenser Dynamic Condenser DesignDesignMelanie Melanie RondotRondotAugust 5, 2004August 5, 2004University of Illinois at Chicago NSFUniversity of Illinois at Chicago NSF--REU 2004REU 2004

Advisors:Advisors:Professor Andreas LinningerProfessor Andreas LinningerAndrés Malcolm, graduate studentAndrés Malcolm, graduate student

Organic solvents Volatile Organic Compounds (VOCs) in air emissions

VOC emissions regulated by EPA

Pharmaceutical ProcessPharmaceutical Process

Source: EPA Office of Compliance Sector Notebook Project: Profile of the Pharmaceutical Manufacturing Industry; September 1997

Flow diagram for typical pharmaceutical process:

Reactor

Condenser

Product

Project DescriptionProject Description

Surface condensationSurface condensationCondenser Model using MATLAB Condenser Model using MATLAB

Steady State Steady State DynamicDynamic

Uncertainty Uncertainty Operating ConditionsOperating ConditionsEstimated ParametersEstimated Parameters

Control SystemControl System

Condenser ModelCondenser Model

Fcool,Tcooln-1

Fgn-1,Tg

n-1

Wall, Twalln

CoolantTcool

n , Ncool

GasTg

N,NgN

Fcon,Tco

n

Fcool,Tcooln

Qw-cooln

Fgn,Tg

n

Qw-gn

Finite Volume Discretization:

Gas Inlet

Gas Outlet

CoolantInlet

CoolantOutlet

Condensate Outlets

Condenser TheoryCondenser Theory

Energy BalancesEnergy BalancesMass BalancesMass BalancesDiffusion EquationsDiffusion Equations

Diffusion EquationsDiffusion Equations

0I g

n n ncondensatey y F≥ ⇒ =

No condensationNo condensation

1. . .ln1

I

nn ABcondensate n

g

yA D CFyδ

−= −

DiffusionDiffusion--Controlled CondensationControlled Condensation

MATLAB ModelMATLAB ModelUser defines

Condenser geometryPhysical propertiesInitial temperaturesInitial flow rates

Program calculates system variables (h, Dab, Cp, etc…)

Steady State ModelSteady State Model

Simultaneous solution of mass and energy balances using fsolveTemperature, concentration, and flow profiles

0 0.5 1 1.5 2 2.5 3200

300

400S teady S tate Condens er

Tem

p (K

)

0 0.5 1 1.5 2 2.5 30

0.1

0.2

VO

C C

onc.

(mol

fr.)

0 0.5 1 1.5 2 2.5 35

10

15

Fcon

b (m

ol/s

)

0 0.5 1 1.5 2 2.5 30

0.2

0.4

Length (m)

Fcon

(mol

/s)

gaswall

coolantgasw all

20% Inlet VOC Concentration

0 0.5 1 1.5 2 2.5 30

200

400S teady S tate Condens er

Tem

p (K

)

0 0.5 1 1.5 2 2.5 30

0.2

0.4

VO

C C

onc.

(mol

fr.)

0 0.5 1 1.5 2 2.5 310

20

30

Fcon

b (m

ol/s

)

0 0.5 1 1.5 2 2.5 30

0.5

1

Length (m)

Fcon

(mol

/s)

c oolantgasw all

gaswall

40% Inlet VOC Concentration

ExplanationExplanation

Appropriate concentration Appropriate concentration gradient gradient ----> condensation> condensation

Energy balancesEnergy balancesn nw g w coolQ Q− −=

.( )n n nw cool cool w coolQ T Tα− = −

( ). .( ) ( )n n n n n v nw g g condensate pg g w g wQ Q F C T T H T− = + − + ∆

.( )n n ng g g wQ T Tα= −

0 0.5 1 1.5 2-1

0

1S teady S ta te Condens er

Qga

s (k

J/s)

0 0.5 1 1.5 20

10

20

30

Qco

nd (k

J/s)

0 0.5 1 1.5 20

10

20

30

Length (m)

Qdi

sp (k

J/s)

40% Inlet VOC Concentration -Heat Flow Profiles

Limiting ConditionLimiting Condition

Heat Transfer Limited CondensationHeat Transfer Limited Condensation

( );( )

nw gn n n n n

g w g w condensate v ng w

QT T T T F

H T−≤ ⇒ = =

∆

0 0.5 1 1.5 2 2.5 3200

300

400S teady S tate Condens er

Tem

p (K

)

0 0.5 1 1.5 2 2.5 30

0.2

0.4

VO

C C

onc.

(mol

fr.)

0 0.5 1 1.5 2 2.5 320

25

30

Fcon

b (m

ol/s

)

0.5

1

con

(mol

/s)

gaswall

coolantgaswall

0 0.50

0.5

1

Qga

s (k

J/s)

20

30

nd (k

J/s)

40% Inlet VOC Concentration with Heat Transfer Limitation

Dynamic ModelDynamic Model

Introduces change into system Simultaneous solution of mass and energy balances using ode15sInitial values obtained from steady state solution

Dynamic Model OutputDynamic Model Output

Uncertain ParametersUncertain Parameters

Operating ConditionsOperating ConditionsInlet Gas Temperature Inlet Gas Temperature Inlet Coolant TemperatureInlet Coolant TemperatureInlet Flowrate of Condensable SpeciesInlet Flowrate of Condensable Species

Estimated ParametersEstimated ParametersHeat Transfer Coefficient of GasHeat Transfer Coefficient of GasDiffusion CoefficientDiffusion Coefficient

Uncertainty Evaluation:Uncertainty Evaluation:ProcedureProcedure

LevelsLevelsTg_inTg_in: 350 ± 5 K: 350 ± 5 KTcool_inTcool_in: 230 ± 2 K: 230 ± 2 KFconb_inFconb_in: 15 ± 1 mol/s: 15 ± 1 mol/sHgasHgas (initial): calculated ± 20%(initial): calculated ± 20%Dab (initial): calculated ± 20%Dab (initial): calculated ± 20%

Outlet Gas Temperature vs. Inlet Gas Temperature

y = 0.8814x - 41.819R2 = 1

261

262

263

264

265

266

267

268

269

270

271

272

344 345 346 347 348 349 350 351 352 353 354 355 356

Inlet Gas Temperature (K)

Out

let G

as T

empe

ratu

re (K

)

Outlet Gas Temperature vs. Inlet Coolant Temperature

y = 0.1407x + 234.3R2 = 0.9996

266.3

266.4

266.5

266.6

266.7

266.8

266.9

267.0

227.6 228.0 228.4 228.8 229.2 229.6 230.0 230.4 230.8 231.2 231.6 232.0 232.4

Inlet Coolant Temperature (K)

Out

let G

as T

empe

ratu

re (K

)

SS Uncertainty Evaluation: SS Uncertainty Evaluation: Independent Variation of 1 VariableIndependent Variation of 1 Variable

Outlet Gas Temperature vs. Inlet Condensable Flowrate

y = -4.7536x + 337.95R2 = 1

260

262

264

266

268

270

272

13.8 14.0 14.2 14.4 14.6 14.8 15.0 15.2 15.4 15.6 15.8 16.0 16.2

Inlet Condensable Flowrate (mol/s)

Out

let G

as T

empe

ratu

re (K

)

SS Uncertainty Evaluation: SS Uncertainty Evaluation: Independent Variation of 1 VariableIndependent Variation of 1 Variable

Outlet Gas Temperature vs. Heat Transfer Coefficient of Gas (Initial Value)

y = -450.94x + 326.71R2 = 0.9991

250

255

260

265

270

275

280

285

0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17Heat Transfer Coefficient of Gas (Initial Value) ( kJ / (s*m^2*K) )

Out

let G

as T

empe

ratu

re (K

)

Outlet Gas Temperature vs. Diffusion Coefficient (Initial Value)

y = -14.415x + 324.42R2 = 0.9994

250

255

260

265

270

275

280

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0

Diffusion Coefficient (Initial Value) ( mol / (s*m^2*atm) )

Out

let G

as T

empe

ratu

re (K

)

SS Uncertainty Evaluation: SS Uncertainty Evaluation: Simultaneous Variation of 2 VariablesSimultaneous Variation of 2 VariablesOutlet Gas Temperature vs. Variation in Inlet Gas and Coolant Temperatures

y = 0.9423x + 266.65R2 = 1

266

267

268

269

270

271

272

0 1 2 3 4 5 6

Level of Variation in Inlet Gas and Coolant Temperatures

Out

let G

as T

empe

ratu

re (K

)

Outlet Gas Temperature vs. Variation in Inlet Coolant Temperature and Inlet Condensable Flowrate

y = 1.0037x + 266.66R2 = 1

266

267

268

269

270

271

272

0 1 2 3 4 5 6

Level of Variation in Inlet Coolant Temperature and Inlet Condensable Flowrate

Out

let G

as T

empe

ratu

re (K

)

Outlet Gas Temperature vs. Variation in Inlet Gas Temperature and Inlet Condensable Flowrate

y = 1.8291x + 266.66R2 = 1

266

268

270

272

274

276

278

0 1 2 3 4 5 6

Level of Variation in Inlet Gas Temperature and Inlet Condensable Flowrate

Out

let G

as T

empe

ratu

re (K

)

Control SystemControl System

Influence system toward operation about set point by adjusting coolant flowrate

( 1)e Tg n Tsp= + −Error: Control Action:1*( )IT

Gc kc e edt= + ∫

Control System: Control System: Decrease Inlet Coolant TemperatureDecrease Inlet Coolant Temperature

0 50 100 150 200 250230

240

250

260

270Temporary repons e of element a

Time (s )

Tem

p (K

)

0 50 100 150 200 250266

266.5

267

267.5

268

268.5

Time (s )

Gas

Tem

p (K

)

0 50 100 150 200 250-2

-1.5

-1

-0.5

0

0.5

Time (s )

Erro

r (K

)

0 50 100 150 200 2500

5

10

15

Time (s )

Coo

lant

Flo

wra

te (k

g/s)

GasCoolantWall

Response to 20% Decrease in Inlet Coolant Temperature at t = 120s

Tsp = 268.2K

Control System: Control System: Increase Inlet Coolant TemperatureIncrease Inlet Coolant Temperature

Response to 20% Increase in Inlet Coolant Temperature at t = 120s

Tsp = 268.2K

Suggested Future WorkSuggested Future Work

Run simulations and uncertainty trials for systems with Run simulations and uncertainty trials for systems with different species and condenser geometriesdifferent species and condenser geometries

Introduce system variable calculations into model for Introduce system variable calculations into model for treatment of inlet streams containing more than one treatment of inlet streams containing more than one condensable speciescondensable species

Compare simulation results with experimental data to judge Compare simulation results with experimental data to judge accuracy and determine magnitude of error in parameter accuracy and determine magnitude of error in parameter estimations (estimations (CpgasCpgas, , hgashgas, Dab), Dab)

Gather information regarding cryogenic cooling systems and Gather information regarding cryogenic cooling systems and cost data for condenser construction and operationcost data for condenser construction and operation

AcknowledgementsAcknowledgements

Faculty, graduate students, and postFaculty, graduate students, and post--doctoral researchers in doctoral researchers in the Chemical Engineering Department at the University of the Chemical Engineering Department at the University of Illinois at Chicago, particularly Professor Andreas Illinois at Chicago, particularly Professor Andreas LinningerLinningerand and AndrésAndrés MalcolmMalcolm

The National Science FoundationThe National Science Foundation