Operation, Modeling and Analysis of the Reverse Water Gas Shift Process Jonathan Whitlow Florida...

Operation, Modeling and Analysis of the Reverse Water

Gas Shift Process

Jonathan Whitlow

Florida Institute of Technology

NASA/ASEE Summer Faculty Program

August 1, 2001

Overview of Presentation

• Description of RWGS Process

• Gas Chromatograph Composition Analysis

• Presentation and Analysis of Operating Data

• Problems Encountered with RWGS Operation

• Description and Evaluation of Matlab Models

• Conclusions and Recommendations

RWGS Photo

CO2

CondenserCatalyticReactor

MembraneSeparator

2

2

2O

2

in Q

F 1

W

2 3 4

R

Electrolysis

RecycleCompressor

2

2O

2

H

H

CO

CO

H

H

H

CO

CO

Q out

H

O2

2

RWGS Process Flow DiagramRWGS Process Flow Diagram

RWGS Flow Schematic

Composition Analysis

• Analysis is Key to Mass Balance Models

• Insufficient Calibration for use of Mass Spectrophotometer

• Gas Chromatograph utilized for Analysis– TCD for CO and CO2

– HID for H2

0.00 20000.00 40000.00 60000.00 80000.00 100000.00

0

10

20

30

40

50

60

CO2 Data CO2 Calculated

% C

arbo

n D

ioxi

de

GC Area Count (TCD)

Carbon Dioxide GC Calibration

0.00 50000.00 100000.00 150000.00

0

20

40

60

80

100

CO Data CO Calculated

% C

arbo

n M

onox

ide

GC Area Count (TCD)

Carbon Monoxide GC Calibration

Hydrogen GC Calibration

0.0 2.0x106 4.0x106 6.0x106 8.0x106 1.0x107 1.2x107 1.4x107

0

10

20

30

40

50 H2 Data H2 Calculated

% H

ydro

gen

GC Area Count (HID)

Summary of RWGS Operating Data

Date # Steady States GC Analysis Electrolysis Sample Frequency7/2/2001 1 ?? no yes 60 seconds7/3/2001 1 ?? no yes 60 seconds7/5/2001 1 ?? no yes 60 seconds7/9/2001 1 partial no 60 seconds7/18/2001 3 yes no 10 seconds7/19/2001 3 yes no 10 seconds

7/27/2001 2 yes no 10 seconds

July 3 Reactor Temperatures (Electrolysis On)

0.00 5000.00 10000.00 15000.00330

340

350

360

370

380

390

T2 T3

Tem

pera

ture

(C)

Time(s)

0.00 5000.00 10000.00 15000.00 20000.00

330

340

350

360

370

380

390

PC1=44 psiaPC1=60 psiaPC1=53 psia

T2 T3

Tem

pera

ture

(C)

Time(s)

July 19 Reactor Temperatures

July 3 CO Vent {R9} Flow (Electrolysis On)

0.00 5000.00 10000.00 15000.000.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

PC1=44 psia

Feed Flow = 2 slpm CO2 & 0.1 slpm H2

R9

Flo

w (

slpm

)

Time(s)

July 18 CO Vent {R9} Flow PC1 Set Point = 53 psia

0.00 5000.00 10000.00 15000.00 20000.00 25000.000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Feed Flow = 1.0 slpm H2 & CO2


R9

Flo

w (

splm

)

Time(s)

0.00 5000.00 10000.00 15000.00 20000.000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

PC1=53 psiaPC1=44 psia

PC1=60 psia

R9

Flo

w (

slpm

)

Time(s)

July 19 CO Vent {R9} Flow Feed Flow=1.3 slpm CO2 & H2

July 27 CO Vent {R9} Flow Feed Flow=1.1 slpm CO2 & H2

0.00 5000.00 10000.00 15000.000.0

0.5

1.0

1.5

2.0

2.5

3.0

PC1=60 psiaPC1=53 psia

R9

Flo

w (

slpm

)

Time(s)

July 3 Membrane P (Electrolysis On)

0.00 5000.00 10000.00 15000.0025

26

27

28

29

30

PC1=44 psia

Feed Flow = 2slpm CO2 & 0.1 slpm H2

Mem

bran

e P

ress

ure

Dro

p (p

si)

Time(s)

July 18 Membrane PPC1 Set Point = 53 psia

0.00 5000.00 10000.00 15000.00 20000.00 25000.0034.0

34.5

35.0

35.5

36.0

36.5

37.0

37.5

38.0



Mem

bran

e P

ress

ue

Dro

p (p

si)

Time(s)

0.00 5000.00 10000.00 15000.00 20000.00

26

28

30

32

34

36

38

40

42

PC1=44 psia

PC1=60 psia

PC1=53 psia

Mem

bran

e P

ress

ure

Dro

p (p

si)

Time(s)

July 19 Membrane PFeed Flow=1.3 slpm CO2 & H2

July 27 Membrane PFeed Flow=1.1 slpm CO2 & H2

0.00 5000.00 10000.00 15000.00

34

36

38

40

42

44

46

PC1=60 psia

PC1=53 psia

Mem

bran

e P

ress

ure

Dro

p (p

si)

Time(s)

July 3 Recycle {R12} Flow & Membrane Feed (R8) (Electrolysis On)

0.00 5000.00 10000.00 15000.0028

30

32

34

36

38

40

42

Feed Flow = 2slpm CO2 & 0.1 slpm H2

PC1=44 psia

R8 R12

Flo

w (

slpm

)

Time(s)

July 18 Recycle {R12}PC1 Set Point = 53 psia

0.00 5000.00 10000.00 15000.00 20000.00 25000.00

26

28

30

32

34

36

38 Feed Flow = 1.2 slpm H2 & CO2


Time(s)

R12

Flo

w (

slpm

)

July 19 Recycle {R12} & Membrane Feed (R8) Flow Feed Flow=1.3 slpm CO2 & H2

0.00 5000.00 10000.00 15000.00 20000.0031

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

PC1=44 psia

PC1=60 psia

PC1=53 psia

R8 R12

Flo

w (

slpm

)

Time(s)

July 27 Membrane Feed (R8) Flow Feed Flow=1.1 slpm CO2 & H2

0.00 5000.00 10000.00 15000.0022

24

26

28

30

32

34

36

38

PC1=60 psia

PC1=53 psia

R8

Flo

w (

slpm

)

Time(s)

RWGS July 18 Mass Balance Summary

Date Port Time %H2 %CO2 %CO Port 2 Port 3 Port 4 Port 7 Feed

7/18/2001 3 9:30 2.48 2.97 94.55 Flow Flow Flow Flow Flow

7/18/2001 3 9:50 2.70 2.83 94.47 30.608 1.022 30.541 32.541 2.000 slpm 0.96 MB. Errror (slpm)7/18/2001 2 10:10 70.85 22.67 6.49 1.2517 0.0418 1.2489 1.3307 0.0818 gmole/min 3.12 %Error7/18/2001 2 10:25 70.08 23.17 6.75 28.784 1.015 28.595 30.595 2.000 CO2 adjusted 0.83 Adjusted CO2 Errror7/18/2001 4 10:40 71.91 24.50 3.58 1.1771 0.0415 1.1694 1.2511 0.0818 gmole/min 2.87 %Error

7/18/2001 7 10:55 69.83 26.71 3.47Comp. Bal. H2 CO2 CO

In 2 20.864 6.786 1.960 Overall Balance ErrorOut 3 0.026 0.029 0.959 Added to port 2Out 4 20.564 7.007 1.024Error 0.273 -0.250 -0.023




7/18/2001 4 2:35 66.26 29.41 4.337/18/2001 4 2:45 65.67 29.82 4.51 Comp. Bal. H2 CO2 CO7/18/2001 7 3:00 64.46 31.45 4.10 In 2 16.861 7.522 2.116 Overall Balance Error7/18/2001 7 3:10 63.84 31.95 4.21 Out 3 0.013 0.013 0.988 Added to port 27/18/2001 7 3:20 63.59 32.18 4.23 Out 4 16.812 7.547 1.1267/18/2001 3 3:35 1.34 1.44 97.22 Error 0.036 -0.038 0.0027/18/2001 3 3:45 1.20 1.42 97.38




7/18/2001 4 5:00 77.27 20.80 1.937/18/2001 7 5:15 75.76 22.55 1.69 Comp. Bal. H2 CO2 CO7/18/2001 7 5:25 75.75 22.57 1.67 In 2 25.333 8.126 1.864 Overall Balance Error

Out 3 0.059 0.076 1.144 Added to port 2Out 4 26.205 7.189 0.650Error -0.932 0.861 0.071

RWGS July 18 Operation SummaryDate Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3 T5

7/18/2001 3 9:30 2.48 2.97 94.55 Flow Del P Port 2 Port 4 Conversion Ratio

7/18/2001 3 9:50 2.70 2.83 94.477/18/2001 2 10:10 70.85 22.67 6.497/18/2001 2 10:25 70.08 23.17 6.75 2.0 35.94 52.65 16.71 97.37 1.0223 379.06 342.11 5.677/18/2001 4 10:40 71.91 24.50 3.587/18/2001 7 10:55 69.83 26.71 3.47

Date Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3 T5


7/18/2001 3 1:40 1.90 1.22 96.887/18/2001 3 2:00 0.89 1.25 97.867/18/2001 2 2:10 63.79 28.16 8.057/18/2001 2 2:20 63.47 28.61 7.927/18/2001 4 2:35 66.26 29.41 4.337/18/2001 4 2:45 65.67 29.82 4.51 2.0 36.71 52.60 15.90 98.66 1.0175 378.80 344.10 5.617/18/2001 7 3:00 64.46 31.45 4.107/18/2001 7 3:10 63.84 31.95 4.217/18/2001 7 3:20 63.59 32.18 4.237/18/2001 3 3:35 1.34 1.44 97.227/18/2001 3 3:45 1.20 1.42 97.38

Date Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3 T5


7/18/2001 3 4:15 5.00 6.19 88.817/18/2001 2 4:25 71.02 23.65 5.337/18/2001 2 4:35 72.42 22.36 5.227/18/2001 4 4:50 76.68 21.43 1.89 2.4 34.68 52.76 18.08 95.04 1.0828 379.82 342.81 5.627/18/2001 4 5:00 77.27 20.80 1.937/18/2001 7 5:15 75.76 22.55 1.697/18/2001 7 5:25 75.75 22.57 1.67


7/19/2001 3 10:15 18.85 12.88 68.27

7/19/2001 3 10:30 17.90 12.78 69.32 39.993 1.496 40.962 43.562 2.600 slpm 2.46 MB. Errror (slpm)7/19/2001 3 10:40 18.62 12.47 68.92 1.6355 0.0612 1.6751 1.7814 0.1063 gmole/min 6.16 %Error7/19/2001 2 10:55 75.99 20.00 4.01 37.909 1.447 38.822 41.422 2.600 CO2 adjusted 2.36 Adjusted CO2 Errror7/19/2001 2 11:05 75.77 20.08 4.15 1.5502 0.0592 1.5876 1.6939 0.1063 6.22 %Error

7/19/2001 4 11:25 78.63 19.97 1.407/19/2001 4 11:35 78.40 20.22 1.38 Comp. Bal. H2 CO2 CO7/19/2001 7 11:50 76.42 22.29 1.28 In 2 30.555 8.070 1.644 Overall Balance Error7/19/2001 7 12:00 76.46 22.16 1.38 Out 3 0.267 0.184 0.996 Added to port 2

Out 4 30.480 7.801 0.541Error -0.193 0.086 0.107




7/19/2001 4 1:30 75.91 21.93 2.157/19/2001 7 1:45 74.79 23.28 1.94 Comp. Bal. H2 CO2 CO7/19/2001 7 1:55 74.33 23.73 1.94 In 2 29.428 8.696 2.047 Overall Balance Error


Date Port Time %H2 %CO2 %CO

7/19/2001 3 2:15 7.88 6.80 85.32 Bad Analysis7/19/2001 3 2:25 2.95 6.89 90.167/19/2001 3 4:20 4.18 11.47 84.35


RWGS July 19 Operation SummaryDate Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3


7/19/2001 3 10:30 17.90 12.78 69.327/19/2001 3 10:40 18.62 12.47 68.927/19/2001 2 10:55 75.99 20.00 4.017/19/2001 2 11:05 75.77 20.08 4.15 2.6 33.54 52.87 19.32 79.46 1.1508 378.75 341.327/19/2001 4 11:25 78.63 19.97 1.407/19/2001 4 11:35 78.40 20.22 1.387/19/2001 7 11:50 76.42 22.29 1.287/19/2001 7 12:00 76.46 22.16 1.38

Date Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3


7/19/2001 3 12:40 7.03 6.25 88.817/19/2001 2 12:55 73.17 21.69 5.147/19/2001 2 1:05 73.34 21.60 5.057/19/2001 4 1:20 75.88 21.97 2.14 2.6 39.42 59.69 20.27 93.09 1.0570 378.97 341.427/19/2001 4 1:30 75.91 21.93 2.157/19/2001 7 1:45 74.79 23.28 1.947/19/2001 7 1:55 74.33 23.73 1.94

Date Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3


7/19/2001 3 2:25 2.95 6.89 90.167/19/2001 3 4:20 4.18 11.47 84.35 2.6 27.11 44.08 16.97 94.62 1.2870 378.19 342.23





Comp. Bal. H2 CO2 COIn 2 25.099 7.332 1.986 Overall Balance Error




7/27/2001 3 3:30 1.00 1.06 97.94 29.437 1.109 29.328 31.528 2.200 slpm 1.00 MB. Errror (slpm)7/27/2001 2 3:55 62.16 29.57 8.27 1.2038 0.0453 1.1993 1.2893 0.0900 gmole/min 3.40 %Error7/27/2001 2 4:05 61.50 30.09 8.41 27.154 1.106 26.793 28.993 2.200 CO2 adjusted 0.74 Adjusted CO2 Errror7/27/2001 4 4:30 62.01 32.97 5.02 1.1104 0.0452 1.0956 1.1856 0.0900 2.74 %Error7/27/2001 4 4:40 61.16 33.54 5.317/27/2001 3 4:55 1.47 1.06 97.47 Comp. Bal. H2 CO2 CO7/27/2001 3 5:05 0.93 0.83 98.24 In 2 17.248 8.323 2.327 Overall Balance Error

Out 3 0.007 0.012 1.086 Added to port 2Out 4 16.500 8.909 1.384Error 0.741 -0.598 -0.143

RWGS July 27 Operation Summary

Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/H2 Feed T2 T3 T5

3 12:30 4.57 7.22 88.22 Flow Del P Port 2 Port 4 Conversion Ratio

3 12:40 2.43 6.05 91.522 1:05 72.93 21.30 5.774 1:20 76.86 20.91 2.234 1:35 76.78 20.92 2.30 2.20 34.73 52.63 17.90 96.37 1.0559 378.77 344.15 5.46

Port Time %H2 %CO2 %CO Feed mem P5 P8 Overall R9/Feed T2 T3 T5

3 3:20 0.33 1.11 98.56 Flow Del P Port 2 Port 4 Conversion Ratio

3 3:30 1.00 1.06 97.942 3:55 62.16 29.57 8.272 4:05 61.50 30.09 8.414 4:30 62.01 32.97 5.02 2.20 42.06 59.40 17.34 99.34 1.0079 378.18 344.92 5.834 4:40 61.16 33.54 5.313 4:55 1.47 1.06 97.473 5:05 0.93 0.83 98.24

Experimental Feed mem P5 P8 Overall R9/H2 Feed T2 T3 T5Run Flow P Port 2 Port 4 Conversion Ratio

7/18/01 9:30-10:55 2.0 35.94 52.65 16.71 97.37 1.0146 379.06 342.11 5.677/18/01 1:15-3:45 2.0 36.71 52.60 15.90 98.66 1.0175 378.80 344.10 5.617/18/01 4:00-5:25 2.4 34.68 52.76 18.08 95.04 1.0828 379.82 342.81 5.627/19/01 1:15-12:00 2.6 33.54 52.87 19.32 79.46 1.1508 378.97 341.42 5.887/19/01 12:30-1:55 2.6 39.42 59.69 20.27 93.09 1.0570 378.97 341.42 5.887/19/01 2:15-4:20 2.6 27.11 44.08 16.97 94.62 1.2870 378.19 342.23 5.757/27/01 12:30-1:35 2.2 34.73 52.63 17.90 96.37 1.0559 378.77 344.15 5.467/27/01 3:20-5:05 2.2 42.06 59.40 17.34 99.34 1.0079 378.18 344.92 5.83

RWGS Operation Summary

Problems Encountered in RWGS Operation

• Water Level Control is a Major Process Disturbance

• Non Uniform Temperature Across Reactor Catalyst Bed

• Temperature T2 had to be controlled by adjusting T3 Set Point

• Solenoid Valves (SV13 & SV14) tied to RWGS Interlocks Stuck Shut (Replaced with Coupling)

• Calibration on Flow Sensors is Inaccurate

• Some of the Redundant Sensors don’t work (P7 & R11)

• Electrolysis use is Limited by High Water Conductivity

Set Temperatures, Pressures, Conversion & Recycle Molar Flow Rates

Set Temperatures, Pressures, Conversion & Recycle Molar Flow Rates

Solve for Reactor Entrance & Exit Molar Flow Rates

Solve for Reactor Entrance & Exit Molar Flow Rates

Perform Isothermal & Isobaric Phase Equilibrium Calculations for the Condenser

Perform Isothermal & Isobaric Phase Equilibrium Calculations for the Condenser

Solve Equations for Membrane SeparationSolve Equations for Membrane Separation

Are Recycle Molar Flows Equal to Starting Values ?Are Recycle Molar Flows Equal to Starting Values ?

No

Yes Exit

Update Recycle Molar Flow Rates

Start

RWGS Model Development(Mass Balance Algorithm)

• Equilibrium favors left side of reaction unless very high temperatures are achievedCO2 + H2 <-----> CO + H2O

• @400 CentigradeK = [CO][H2O] = 0.086

[CO2][H2]

RWGS Reactor

• Reactor analysis assumes that equilibrium conversion is achieved.

• Conversion is found by solving a quadratic equation.

RWGS Reactor

K = [CO] [ H O]

[ CO ] [ H ] =

( + x ) ( + x )

( - x ) (1 - x )2

2 2

CO eq H O eq

CO eq eq

2

2

Condenser• Condenser is used to remove water

from the reactor exit stream • Ideal cases are assumed in modeling

the condenser Raoult’s Law for water in vapor phase

Partial Pressure = Vapor Pressure Henry’s Law for dissolved gases in liquid phase

Solubility is a function of temperature in pure H2O

Model Representation for N Stage Counter-Current Membrane

Feed

Permeate

VN-1

y j,N-1

V k+1

y j,k+1

VN

y j,N

LN+1

x j,N+1

L k+2

x j,k+2

L k+1

x j,k+1

V k

y j,k

L k

x j,k

L 2

x j,2

L 1

x j,1

V k-1

y j,k-1

V 1

y j,1

V 0

y j,0

m j,N m j,k-1 m j,k m j,1

Residue

Sweep

Stage N Stage k+1 Stage k Stage 1

LN

x j,N

Summary of Membrane ModelingCalculated Actual Absolute Calculated Actual Absolute Calculated Actual Absolute

7/18/01 9:30-10:55 H2 H2 Difference CO2 CO2 Difference CO CO DifferenceFeed 20.591 20.864 0.273 7.036 6.786 0.25 1.983 1.96 0.023

Permeate 20.552 20.564 0.012 7.008 7.007 0.001 0.952 1.024 0.072Reject 0.039 0.026 0.013 0.028 0.029 0.001 1.031 0.959 0.072

7/18/01 1:15-3:45Feed 16.825 16.861 0.036 7.56 7.522 0.038 2.114 2.116 0.002

Permeate 16.812 16.812 0 7.547 7.547 0 1.126 1.126 0Reject 0.013 0.013 0 0.013 0.013 0 0.988 0.988 0

7/18/01 4:00-5:25Feed 26.265 25.333 0.932 7.265 8.126 0.861 1.793 1.864 0.071

Permeate 26.058 26.205 0.147 7.162 7.189 0.027 0.64 0.65 0.01Reject 0.207 0.059 0.148 0.103 0.076 0.027 1.153 1.144 0.009

7/19/01 1:15-12:00Feed 30.748 30.555 0.193 7.984 8.07 0.086 1.537 1.644 0.107

Permeate 30.011 30.48 0.469 7.681 7.801 0.12 0.3831 0.541 0.1579Reject 0.737 0.267 0.47 0.303 0.184 0.119 1.154 0.996 0.158

7/19/01 12:30-1:55Feed 29.552 29.428 0.124 8.605 8.696 0.091 2.028 2.047 0.019

Permeate 29.324 29.463 0.139 8.486 8.523 0.037 0.723 0.834 0.111Reject 0.228 0.09 0.138 0.119 0.082 0.037 1.305 1.194 0.111

7/27/01 12:30-1:35Feed 25.603 25.099 0.504 7.035 7.332 0.297 1.986 1.779 0.207

Permeate 25.515 25.563 0.048 6.987 6.96 0.027 0.753 0.747 0.006Reject 0.088 0.04 0.048 0.048 0.076 0.028 1.026 1.032 0.006

7/27/01 3:20-5:05Feed 16.507 17.248 0.741 8.921 8.323 0.598 2.47 2.327 0.143

Permeate 16.43 16.5 0.07 8.843 8.909 0.066 1.032 1.384 0.352Reject 0.077 0.007 0.07 0.078 0.012 0.066 1.438 1.086 0.352

Conclusions

• High Conversion of H2 can be Achieved with Proper Operating Conditions

• Modifications are needed to Improve Operation and Analysis of RWGS with Electrolysis

• Further Experimental Testing is Needed to Better Characterize RWGS Process

• Membrane Model is Valid, Further Work is Needed to Refine and Validate the rest of RWGS Models

Recommended Modifications• Make Modifications to Sampling System

• Evaluate Other Methods for H2 Analysis– Calibrate Mass Spec

– GC using TCD with Argon Carrier

• Install Low Pressure Drop Bleed Valves for Water Level Control

• Recalibrate Flow Sensors Around Membrane (R8 & R12)

• Control Reactor Temperature with T2

• Add Integral Action to Pressure & Temperature Controller

Further Experimental Tests

• Examine Additional Steady States at Different System Pressures/Membrane P (@ Constant Temperature & Feed Ratio)

• Examine Additional Steady States at Different Feed Rates (@ Constant Temperature & Feed Ratio)

• Examine Effects of Varying Reactor Temperature• Examine Effects of Varying Fresh Feed Ratios

Operation, Modeling and Analysis of the Reverse Water Gas Shift Process Jonathan Whitlow Florida...

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Transcript of Operation, Modeling and Analysis of the Reverse Water Gas Shift Process Jonathan Whitlow Florida...