(AGRU) ACID GAS SOUR SHIFT: CASE STUDY IN REFINERY GAS TREATMENT

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(AGRU) ACID GAS
SOUR SHIFT: CASE
STUDY IN REFINERY
GAS TREATMENT
Case Study: #0978766GB/H
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CONTENTS
CASE STUDY OVERVIEW
Syn Gas Sour Shift: Process Flow Diagram
AGR: Acid Gas to VULCAN SYSTEMS Sour Gas Shift
DESIGN BASIS:
ACID GAS REACTOR CATALYST SPECIFICATION
SOUR SHIFT CASE
SHIFT REACTOR CATALYST SPECIFICATIONS
COS REACTOR CATALYST SPECIFICATIONS
SWEET SHIFT CASE
PERFORMANCE SIMULATION RESULTS
SOUR SHIFT SECTION
1 Cases Considered
2 Catalyst Used
3 Client Requirements
4 Oxygen and Olefins
5 HCN
6 NH3
7 Arsine
8 Input Data Sour Shift Unit
9 Activity (PROPRIETARY)
10 Results

ADIABATIC SWEET SHIFT SECTION: HTS Reactor followed by LTS Reactor
1 Catalyst Used
2 Inlet Operating Temperature HTS Reactor
3 Feed Flow Rate, Inlet Operating Pressure and Feed Composition
HTS Reactor
4 Inlet Operating Conditions LTS Reactor
6 Results: Standard Case as Presented to the Client
7 Results: Inlet Operating Pressure HTS Reactor = 25.2 bara
8 Results: Addition of 100 kmol/h N2
COS HYDROLYSIS SECTION FOR SWEET SHIFT CASE
1 Total Feed Flow Rate, Feed Composition, Direction of Flow, Inlet
Operating Temperature, Inlet Operating Pressure
2 Inlet H2S and COS Levels
3 Equilibrium H2S and COS Levels (COS Hydrolysis Reaction)
5 Results
H2S REMOVAL SECTION AFTER AGR UNIT
(2 Absorbent Beds (VULCAN VSG-EZ200) in Lead/Lag Arrangement)
2 Inlet H2S and COS Levels
3 Client Requirements (All Cases)
4 Results

ISOTHERMAL SWEET SHIFT SECTION: Alternative Approach
VULCAN Simulation Input Data
1 Enthalpy method
2 Cases considered
3 Feed stream data
4 Kinetics
5 Catalyst
6 Catalyst Activity relative to standard
7 Catalyst size and packing details
8 Catalyst pressure drop parameters
9 Catalyst Volume
10 Standard die-off rate
11 BFW Rate
12 Vapor fraction
13 Steam Temperature
14 Steam Pressure
15 Boiling Model
16 Volumetric UA
Isothermal Shift Simulations Results
APPENDIX
Characteristics of Acid Gas Removal Technologies

OVERVIEW
Gas Treating in gas industries, and in oil and chemical facilities is getting more
complex due to emissions requirements established by environmental regulatory
agencies.
Acid Gas Removal (AGR)
Currently, the processes of choice in refinery gas processing facilities for the
removal of acid gases are both the chemical solvent AGR processes based on
aqueous methyldiethanolamine (MDEA) and the physical solvent-based Selexol
process—which uses mixtures of dimethyl ethers of polyethylene glycol.
In most of the refinery acid gas applications now, with both of these AGR
processes, the AGR units are preceded by carbonyl sulfide (COS) hydrolysis
units to convert most of the COS to H2S. This then enables the AGR units to
accomplish deeper total sulfur removal and lower H2S levels.
AGR units remove essentially all of the H2S and CO2 from various refinery gas
streams.
• Fuel gas treating
• Hydrotreater product/fuel gas
• Hydrotreater recycle gas
• Hydrocracker product/fuel gas
• Hydrocracker recycle gas
• LPG liq-liq contactor
• Thermal/catalyst cracker gases

This case study demonstrates how the VULCAN SYSTEMS S2
GP “sour gas shift
process” can provide a technically viable process option in the treatment of an
AGRU’s acid gas stream, for the generation of Synthesis gas suitable for various
downstream refinery and petrochemical processes.
The “Shifted” Syngas can be utilized for co-gen (as fuel to existing gas turbines),
fuel for existing heaters, producing value added products like hydrogen,
substitute natural gas (SNG), carbon monoxide (CO), synthesis gas, etc.
ACID GAS: SOUR SHIFT CASE STUDY

Acid Gas to VULCAN SYSTEMS Sour Gas Shift
ACID GAS REACTOR CATALYST SPECIFICATION
DESIGN BASIS:
SOUR SHIFT CASE
COS REACTOR CATALYST SPECIFICATIONS
SWEET SHIFT CASE
4 1. Data marked v to be specified / confirmed by catalyst vendor.
5
6 2. Allowable pressure drop to include catalyst support material.

Job ACME - Sour Shift Case Item No.
Item Name SHIFT REACTOR CATALYST
1 OPERATING DATA Units INLET OUTLET
2 Component Flow
3 Hydrogen mol % 11.48 v
4 Nitrogen mol % 3.23 v
5 Carbon Monoxide mol % 23.05 v
6 Carbon Dioxode mol % 1.67 v
7 Methane mol % 0.01 v
8 Argon mol % 0.03 v
9 Hydrogen Sulphide mol % 0.63 v
10 Carbonyl Sulphide mol % 0.05 v
11 Ammonia mol % 0.06 v
12 Water mol % 59.79 v
13 Hydrogen Cyanide mol % 0.003 v
14
15
16
17 Total mol %
18 Total Flow kmol/h 14438
19 Total Flow kg/h 279656
20 Actual Volume Flow m3
/h
21 Normal Volume Flow Nm3
/h
22 (at 0°C, 1 bar a)
23 Stream Temperature o
C 215
24 Operating Pressure bar a 37.5
25 Stream Viscosity cP 0.025
26
27 Bed 1 Bed 2
28 Allow able Pressure Drop bar
29 Maximum Temperature o
C
30 Design Temperature o
C
31 Heat Loss kW/m2
32
33 Catalyst Vendor
34 Catalyst Type
35 Catalyst Size / Shape
36 Catalyst Life years
37 Bulk Density kg/m3
38 Bed 1 Bed 2
39 Bed Height mm
40 Bed Diameter mm
41 Bed Volume m3
42 Bed Weight te
43
44 LHSV / VHSV
45 Flow Direction Downwards
46
47
48
49
50
v
v
100.00
v
100.00
14438
279656
-40 min
v
v
0.34 (Note2)
v
v
v
v
v
v
v

Job ACME - Sweet Shift Case Item No.
Item Name COS REACTOR CATALYST
OPERATING DATA Units INLET OUTLET
Component Flow
Hydrogen mol % 21.98 v
Nitrogen mol % 6.20 v
Carbon Monoxide mol % 44.17 v
Carbon Dioxode mol % 3.10 v
Methane mol % 0.01 v
Argon mol % 0.05 v
Hydrogen Sulphide mol % 1.20 v
Carbonyl Sulphide mol % 0.10 v
Ammonia mol % 0.005 v
Water mol % 23.18 v
Hydrogen Cyanide mol % 0.005 v
Total mol %
Total Flow kmol/h
Total Flow kg/h
Actual Volume Flow m3
/h
Normal Volume Flow Nm3
/h
(at 0°C, 1 bar a)
Stream Temperature o
C
Operating Pressure bar a
Stream Viscosity cP
Bed 1 Bed 2
Allow able Pressure Drop bar
Maximum Temperature o
C
Design Temperature o
C
Heat Loss kW/m2
Catalyst Vendor
Catalyst Type
Catalyst Size / Shape
Catalyst Life years
Bulk Density kg/m3
Bed 1 Bed 2
Bed Height mm
Bed Diameter mm
Bed Volume m3
Bed Weight te
LHSV / VHSV
Flow Direction Downwards
v
v
v
v
v
v
v
-40 min
v
v
0.34 (Note 2)
37.8
0.024
201
100.00
7535
155091
100.00
7535
155091
v
v
v

Job ACME - Sweet Shift Case Item No.
Item Name SHIFT REACTOR CATALYST
1 OPERATING DATA Units INLET OUTLET
2 Component Flow
3 Hydrogen mol % 11.55 v
4 Nitrogen mol % 3.26 v
5 Carbon Monoxide mol % 23.22 v
6 Carbon Dioxode mol % 1.29 v
7 Methane mol % 0.01 v
8 Argon mol % 0.03 v
9 Hydrogen Sulphide mol % 0.00 v
10 Carbonyl Sulphide ppmv < 50 v
11 Ammonia ppmv < 0.1 v
12 Water mol % 60.65 v
13 Hydrogen Cyanide ppmv < 0.1 v
14
15
16
17 Total mol %
18 Total Flow kmol/h 14321
19 Total Flow kg/h 274316
20 Actual Volume Flow m3
/h
21 Normal Volume Flow Nm3
/h
22 (at 0°C, 1 bar a)
23 Stream Temperature o
C 210
24 Operating Pressure bar a 33.2
25 Stream Viscosity cP
26
27 Bed 1 Bed 2
28 Allow able Pressure Drop bar
29 Maximum Temperature o
C
30 Design Temperature o
C
31 Heat Loss kW/m2
32
33 Catalyst Vendor
34 Catalyst Type
35 Catalyst Size / Shape
36 Catalyst Life years
37 Bulk Density kg/m3
38 Bed 1 Bed 2
39 Bed Height mm
40 Bed Diameter mm
41 Bed Volume m3
42 Bed Weight te
43
44 LHSV / VHSV
45 Flow Direction Downwards
46
47
48
49
50
v
v
100.00
v
100.00
14321
274316
-40 min
v
v
0.34 (Note 2)
0.025
v
v
v
v
v
v
v

PERFORMANCE SIMULATION RESULTS
Sour Shift Section
Starting Point: In this document only the Sour Shift option will be considered.
The following Cases were considered:
1 Cases Considered
Life Inlet Operating
Pressure
(bara)
Inlet Operating
Temperature
(o
C)
Standard Case SOR SOR Expected 37.5
(= 36.5 barg)
Bed 1: 300*
Bed 2: 280
Standard Case EOR 2 Years
Guaranteed
Lower Inlet Operating
Pressure SOR
SOR Expected
29.5
(= 28.5 barg)Lower Inlet Operating
Pressure EOR
2 Years
Guaranteed
Addition of 100 kmol/h N2
SOR
SOR Expected 37.5
(= 36.5 barg)
Addition of 100 kmol/h N2
EOR
2 Years
Guaranteed
*The Inlet Operating Temperature ad specified by the Client (215o
C) is too low for
sour shift; moreover this temperature is below the dewpoint for water at an Inlet
Operating Pressure of 37.5 bara (= 215o
C).
2 Catalyst Used: VULCAN VIG-SGS202.
The use of this catalyst is allowed here, because the Inlet Operating Pressure is
always lower than 40 bara.
3 Client Requirements:
Required Guaranteed Maximum Catalyst Life (years): 2
Required Guaranteed Maximum CO Slip EOR (i.e. 2 years, mol%, dry): 1.2
Required Expected Total Maximum Catalyst Bed Pressure Drop after 2
Years EOR (bar):
0.34

4 Oxygen and Olefins
There are no oxygen or olefins present in the feed, which would have
resulted in an additional exotherm and a change in the composition of the
feed.
5 HCN
The catalyst hydrogenates 90% of the HCN present in the feed.
6 NH3
The NH3 Level present in the feed will not affect the performance of the
catalyst.
7 Arsine
No mention is made of the presence of arsine. Arsine is a severe catalyst
poison. In view of the fact that coal is the starting point in this process it
would be wise to double-check whether there is really no arsine
whatsoever present in the feed of the Sour Shift Section.

8 Input Data Sour Shift Unit
Lower Inlet
Operating
Pressure
(29.5 bara)
Addition of
100 kmol/h
N2
Standard
Case
Feed Flow Rate (kmol/h, wet): 14438 14538 14438
Feed Flow Rate (Nm3
/h, wet): 323613 325855 323613
Feed Flow Rate (kmol/h, dry): 5806 5906 5806
Feed Flow Rate (Nm3
/h, dry): 130136 132378 130136
Steam Flow Rate (kmol/h): 8632 8632 8632
Steam Flow Rate (Nm3
/h): 193478 193478 193478
Steam/CO Ratio (mol/mol): 2.594* 2.594* 2.594*
Steam/Dry Gas Ratio (mol/mol): 1.4867** 1.4616** 1.4867**
Feed Composition (mol%, dry):
H2
CO
CO2
N2
CH4
Ar
NH3
H2S
HCN
COS
TOTAL
28.5480
57.3198
4.1529
8.0322
0.0249
0.0746
0.1492
1.5667
0.0075
0.1243
100.0000
28.0646
56.3493
4.0826
9.5892
0.0245
0.0733
0.1467
1.5402
0.0074
0.1222
100.0000
28.5480
57.3198
4.1529
8.0322
0.0249
0.0746
0.1492
1.5667
0.0075
0.1243
100.0000
Inerts (mol%, dry): 9.9793 11.5035 9.9793
COS (ppmv, dry): 1243 1222 1243
H2S/COS Ratio (mol/mol): 12.60 12.60 12.60
Inlet Operating Pressure (bara): 29.5
(= 28.5
barg)
37.5
(= 36.5
barg)
37.5
(= 36.5
barg)
Interbed Cooling: Heat
Exchanger
Heat
Exchanger
Heat
Exchanger
Inlet Operating Temperature, Bed
1 (o
C):
300*** 300*** 300***
Inlet Operating Temperature, Bed
2 (o
C):
280*** 280*** 280***
Required Exit CO Slip (mol%, dry) 1.2 1.2 1.2

*This value for the Steam/CO Ratio is high enough to avoid methanation at the
specified Operating Pressure and CO Inlet Level.
**This value for the Steam/Dry Gas Ratio is high enough to avoid methanation.
***This value for these Inlet Operating Temperatures is way above the dewpoint
for water in all Cases.
9 Activity (PROPRIETARY)
For beds 1 and 2 ATE’s of 50 and 30o
C, respectively were used in the
calculations.
10 Results:
Downflow and axial reactors have been assumed. The details are given below:
Results: Standard Case as Presented by the Client
Bed 1 EOR SOR
Expected Exit Operating Temperature (o
C): 498.1 499.3
Expected Catalyst Bed Pressure Drop (bar): -* 0.24
Guaranteed Catalyst Life (Years): 2 N.A.
Gas Exit Composition (mol%, dry):
Inerts**:
H2
CO
CO2
TOTAL
6.72
51.86
6.00
35.42
100.00
6.71
51.96
5.78
35.55
100.00
Exit Steam: Dry Gas Ratio (mol/mol): 0.6755 0.6721
Catalyst Bed Volume, Bed 1 (m3
): 51.00
Catalyst Bed Diameter, Bed 1 D (m): 4.766
Catalyst Bed Height H, Bed 1 (m): 2.859
H/D (-): 0.60
Bed 2 EOR SOR
C): 309.2 308.6

Inerts**:
H2
CO
CO2
TOTAL
6.42
54.04
1.20
38.35
100.00
6.41
54.08
1.09
38.41
100.00
Guaranteed Maximum CO Slip (mol%, dry): 1.20 N.A.
): 51.00
H/D (-): 0.60
*Due to build-up of particulates it is impossible to give a value for the Catalyst
Bed Pressure Drop EOR.
**Inerts = N2 + CH4 + Ar + H2S + COS + NH3 + HCN.
Results: Inlet Operating Pressure = 29.5 bara
Bed 1 EOR SOR
C): 496.4 500.7
Inerts**:
H2
CO
CO2
TOTAL
6.76
51.57
6.63
35.03
100.00
6.71
51.93
5.83
35.52
100.00
): 51.00
H/D (-): 0.60
Bed 2 EOR SOR
C): 312.2 309.1

Inerts**:
H2
CO
CO2
TOTAL
6.43
53.97
1.36
38.25
100.00
6.41
54.08
1.12
38.40
100.00
): 51.00
H/D (-): 0.60
Results: Addition of 100 kmol/h N2
Bed 1 EOR SOR
C): 497.0 498.4
Inerts**:
H2
CO
CO2
TOTAL
7.79
51.26
5.94
35.01
100.00
7.78
51.37
5.69
35.16
100.00
): 51.00
H/D (-): 0.60
Bed 2 EOR SOR
C): 309.1 308.3

Inerts**:
H2
CO
CO2
TOTAL
7.44
53.44
1.19
37.92
100.00
7.44
53.49
1.08
37.99
100.00
): 51.00
H/D (-): 0.60
Amount of Catalyst to be Ordered (m3
): 2 x 51 x 1.03 = 105 m3
.
Comments
In all Cases both beds show an Expected Exit Operating Temperatures of less
than 550o
C, which is acceptable.
Of course the steam content must always stay below dew point level. This is true
for all Cases in both beds.
The Catalyst Bed Pressure Drop is acceptable for sour shift design, but is slightly
higher than the value specified by the Client (= 0.34 bar). Please also note that
the Catalyst Bed Pressure Drops calculated here are for SOR expected only.
The Required Guaranteed Maximum CO Slip EOR (2 years) of 1.2 mol% (dry)
can be achieved for the Standard Case and for the Addition of 100 kmol/h N2
Case.
In all Cases Desulfiding of the catalyst will not occur.
A Catalyst Bed Height of 2.859m is acceptable (less than 5 m).
H/D = 0.60 is acceptable.

A decrease in the Inlet Operating Pressure results in a slightly worse
performance in terms of Catalyst Bed Pressure Drop and in terms of CO Slip
compared to the Standard Case. Slightly larger Catalyst Bed Volumes would be
required here.
The addition of 100 kmol/h N2 results in virtually the same performance as the
Standard Case in terms of Catalyst Bed Pressure Drop and in terms of CO Slip.
The linear velocities are acceptable in the Standard Case and in the Addition of
100 kmol/h N2 Case (less than 0.35 m/s). However, the Lower Inlet Operating
Pressure Case shows linear velocities of 0.43 and 0.36 m/s for Bed 1 and 2,
respectively. Increasing D could decrease these linear velocities, which would be
acceptable because (see above) in the Lower Inlet Operating Pressure Case
slightly larger Catalyst Bed Volumes would be required anyway to meet 1.2 mol%
(dry) CO Slip criterion specified by the Client.
In all Cases the linear velocities are less than 1.5 x the fluidization threshold
velocity (the criterion used to prevent milling of catalyst at the top of the bed in
downflow), which is acceptable.
The wet GHSV is always less than 10000 h-1
, which is fine.

ADIABATIC SWEET SHIFT SECTION: HTS Reactor followed by LTS Reactor
Starting Point: The calculations were carried for 0 years expected and 2 years
guaranteed for the standard case presented by the Customer. Moreover the
impact of the following changes were evaluated:
An 8 bar lower Operating Pressure and the addition of 100 kmol/h N2.
The direction of flow is downflow throughout. Axial reactors are used. The
following data were used in the calculations:
1 Catalysts Used:
HTS Section: VULCAN VSG-F101
LTS Section: VULCAN VSG-C111/112
2 Inlet Operating Temperature HTS Reactor
Inlet Operating Temperature (o
C): Optimized
Calculation Type: OPTIMIZATION
3 Feed Flow Rate, Inlet Operating Pressure and Feed Composition
HTS Reactor:
Lower Inlet
Operating
Pressure (25.2
bara)
Addition of 100
kmol/h N2
Standard Case
Feed Flow Rate (kmol/h,
wet):
14321 14421 14321
Inlet Operating Pressure
(bara):
25.2 33.2 33.2
Feed Composition (mol%,
wet):
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
Water
TOTAL
11.550
3.260
23.220
1.290*
0.010
0.020
60.650
100.000
11.470
3.931
23.059
1.281
0.010
0.020
60.229
100.000
11.550
3.260
23.220
1.290*
0.010
0.020
60.650
100.000

*Please note that the carbon dioxide seems to have been diluted more by the
steam added than the other components. The Carbon Dioxide Component Feed
Flow Rate is here 184.7 kmol/h, whereas the Carbon Dioxide Component Feed
Flow Rate for the H2S Removal Section is 241.1 kmol/h. There is something not
quite right here.
4 Inlet Operating Conditions LTS Reactor:
Inlet Operating Temperature
(o
C):
Optimized
Inlet Operating Pressure
(bara):
To be calculated
Feed Flow Rate (kmol/h, wet): 14321
Feed Composition (mole %,
wet):
= Exit Composition HTS Reactor (to be
calculated)
Calculation Type: OPTIMIZATION
5 Client Requirements:
Guaranteed Minimum Catalyst Lives: 2
(Assumed)
Maximum CO Slip Exit Adiabatic Sweet Shift Section after 2 Years
Guaranteed (mol%, dry):
1.2
Expected Maximum Catalyst Bed Pressure Drop across Adiabatic
Sweet Shift Section after 2 Years (bar):
0.34
6 Results: Standard Case as Presented to the Client:
HTS Catalyst: VULCAN VSG-F101
LTS Catalyst: VULCAN VSG-C111/112
0 Years
Expected (SOR)
2 Years
Guaranteed
(EOR)
Bed 1: HTS Reactor
Guaranteed Catalyst Life (Years): 2
Required Catalyst Bed Volume (m3
): 42.0 (Order: 43.3)
Catalyst Bed Diameter D (m): 4.47
Catalyst Bed Height H (m): 2.68
H/D (-): 0.6
Expected Optimum Inlet Operating
Temperature (o
C):
310.0 310.0
Expected Exit Operating Temperature
(o
C):
507.4 507.4

Expected Catalyst Bed Pressure Drop
(bar):
0.123 0.133
Expected Exit Operating Pressure (bara): 33.1
GHSV (h-1
): 7642.6
Exit Composition (mol%, dry):
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
52.960
5.520
5.870
35.600
0.020
0.030
100.000
52.920
5.520
5.960
35.540
0.020
0.030
100.000
Exit Steam/Dry Gas Ratio (mol/mol) x
100:
69.2 69.4
Exit WGS Approach–to–Equilibrium (o
C): 0.0 3.3
Reduction Potential (-): 0.717
Bed 2: LTS Reactor
): 42.0 (Order: 43.3)
H/D (-): 0.6
Temperature (o
C):
208.4 219.6
(o
C):
240.4 251.3
(bar):
0.145 0.164
GHSV (h-1
): 7642.6
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
55.390
5.230
0.380
38.940
0.020
0.030
100.000
55.240
5.250
0.740
38.720
0.020
0.030
100.000
100:
60.5 61.0

C): 3.7 16.7
Guaranteed Maximum CO Slip Exit LTS
Reactor after 2 Years (mol%, dry):
1.2
Total Expected Catalyst Bed Pressure
Drop across Adiabatic Sweet Shift
Section (bar):
0.268 0.297
7 Results: Inlet Operating Pressure HTS Reactor = 25.2 bara
0 Years
Expected (SOR)
2 Years
Guaranteed
(EOR)
Bed 1: HTS Reactor
): 42.0 (Order: 43.3)
H/D (-): 0.6
Temperature (o
C):
310.0 310.0
(o
C):
510.0 509.6
(bar):
0.161 0.173
GHSV (h-1
): 7642.6
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
52.920
5.520
5.960
35.550
0.020
0.030
100.000
52.810
5.530
6.220
35.390
0.020
0.030
100.000
100:
69.3 69.8
C): 0.0 3.2
Bed 2: LTS Reactor

): 42.0 (Order: 43.3)
H/D (-): 0.6
Temperature (o
C):
207.5 218.9
(o
C):
241.3 252.6
(bar):
0.192 0.217
GHSV (h-1
): 7642.6
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
55.390
5.230
0.390
38.94
0.020
0.030
100.000
55.200
5.250
0.820
38.670
0.020
0.030
100.000
100:
60.5 61.1
C): 3.8 23.4
1.2
Section (bar):
0.353 0.390

8 Results: Addition of 100 kmol/h N2
0 Years
Expected (SOR)
2 Years
Guaranteed
(EOR)
Bed 1: HTS Reactor
): 42.0 (Order: 43.3)
H/D (-): 0.6
Temperature (o
C):
310 310
(o
C):
506.6 506.5
(bar):
0.125 0.135
GHSV (h-1
): 7696.0
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
52.35
6.62
5.77
35.20
0.02
0.03
100.00
52.30
6.63
5.89
35.13
0.02
0.03
100.00
100:
68.4 68.5
C): 0.0 3.5
Bed 2: LTS Reactor
): 42.0 (Order: 43.3)
H/D (-): 0.6
Temperature (o
C):
208.7 219.9
(o
C):
240.4 251.4

(bar):
0.147 0.166
GHSV (h-1
): 7696.0
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
TOTAL
54.78
6.28
0.38
38.51
0.02
0.03
100.00
54.61
6.30
0.75
38.28
0.02
0.03
100.00
100:
59.8 60.4
C): 3.8 18.1
1.2
Section (bar):
0.272 0.301
Comments:
For all Cases the value for the Reduction Potential R is so low that over-
reduction of the HTS Catalyst can be safely ruled out (R is always less than 1.9).
The dew point of the bulk gas inlet the HTS and LTS Reactors is always at least
15o
C lower than the corresponding Inlet Operating Temperature, so there is no
risk of water condensation.
All Operating Temperature regimes encountered are acceptable.
An H/D Ratio of 0.6 is acceptable for HTS and LTS Reactors.
The GHSV of the HTS Reactor is < 8000 h-1
, which is OK.
The Total Expected Catalyst Bed Pressure Drop across the Adiabatic Sweet Shift
Section after 2 Years (bar) was found to be 0.297 bar for the Standard Case,
which meets the Pressure Drop requirement. On the other hand their figure of
0.34 bar is to include catalyst support, which could mean that there might be an
opportunity for VULCAN DPOPTIMIZOR System here.

The Required Guaranteed Maximum CO Slip Exit Adiabatic Sweet Shift Section
after 2 Years is achieved for all Cases (= 1.2 mol%, dry).
The Required Guaranteed Minimum Catalyst Lives are achieved for all Cases.
A decrease in the Inlet Operating Pressure of the HTS Reactor of 8 bar results in
a slightly worse performance in terms of Catalyst Bed Pressure Drop and in
terms of CO Slip compared to the Standard Case. However, the CO Slip
requirement is still met. On the other hand, the Total Expected Catalyst Bed
Pressure Drop across the Adiabatic Sweet Shift Section is a bit too high ( 0.353
and 0.390 bar for 0 years expected and 2 years guaranteed, respectively).
The addition of 100 kmol/h N2 results in virtually the same performance as the
Standard Case in terms of Catalyst Bed Pressure Drop and in terms of CO Slip.
Both the CO Slip requirement and the requirement for the Total Expected
Catalyst Bed Pressure Drop across the Adiabatic Sweet Shift Section are still
met.

COS Hydrolysis Section for Sweet Shift Case (1 Bed of VULCAN A2
ST 99)
Starting Point:
Total Feed Flow Rate (kmol/hr): 7535
Total Feed Flow Rate (Nm3
/hr): 168889
Feed Composition (mol%):
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
Hydrogen Sulphide
Carbonyl Sulphide
Ammonia
Water
Hydrogen Cyanide
TOTAL:
21.980
6.200
44.170
3.100
0.010
0.050
1.200
0.100
0.005
23.180
0.005
100.000
Direction of Flow: Downflow
C): 201 or 125 (See
below)
Inlet Stream Dynamic Viscosity (cP): 0.024
2 Inlet H2S and COS Levels*
H2S (ppmv as S): 12000
COS (ppmv as S): 1000
*As specified by the Customer.
3 Equilibrium H2S and COS Levels (COS Hydrolysis Reaction)
Operating Temperature
(o
C):
201 125
H2S (ppmv as S): 13000 13000
COS (ppmv as S): 0.38 0.10

From the above calculated equilibrium H2S and COS levels it can be concluded
that if an exit COS Level of 0.1 mol% is required the Operating Temperature will
have to be decreased from 201 to 125o
C. An Operating Temperature of 125o
C
will kinetically still be acceptable for VULCAN A2
ST 99, the COS Hydrolysis
Catalyst recommended here.
Required Guaranteed Catalyst Life (VULCAN A2
ST 99) (years): 2
(Assumed)
Required Guaranteed Maximum Exit COS Level (ppmv,
expressed as S):
Unknown
Required Expected Maximum Total Catalyst Bed Pressure Drop
across HDS Section and H2S Removal Section after 2 Years
(bar):
Unknown
5 Results
The Absorbent Bed Pressure Drop:
Exit Operating Temperature (o
C): 201 125
Expected Exit Operating Pressure after 2 Years (bara): 37.6 37.6
Exit Stream Dynamic Viscosity (cP): 0.024
Calculated Required Bed Volume of VULCAN A2
ST 99
(m
3
):
43.6* (Order:
44.9)
Catalyst Bed Height (m): 3.81
H/D (-): 1.0
Guaranteed Minimum Catalyst Bed Life (VULCAN A2
ST
99) (years):
2
Guaranteed Maximum Exit Total COS Level (ppmv): 0.38 0.10
Expected Catalyst Bed Pressure Drop after 2 Years (bar): 0.247 0.201

Exit Composition (mol%):
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
Hydrogen Sulphide
Carbonyl Sulphide
Ammonia
Water
Hydrogen Cyanide
TOTAL:
21.980
6.200
44.170
3.200
0.010
0.050
1.300
0.000
0.005
23.080
0.005
100.000
*This Bed Volume is determined by the minimum acceptable contact time of 20 s.
Please note that our HTS Catalyst (VULCAN VSG-F101) can cope with H2S
levels up to 200 ppmv. The Client has stated that the AGR Unit will remove 99.95
% of all the H2S present (= 13000 ppmv). This means that after the AGR Unit
there will still be 0.0005 x 13000 = 6.5 ppmv H2S present in the feed of the HTS
Unit, which should be OK.
However, if an LTS Section is required the H2S Level must be reduced to 0.1
ppmv, which means that at a temperature of 220o
C a bed of VULCAN EZ200
Zinc oxide will be required.

H2S Removal Section after AGR Unit (2 Absorbent Beds (VULCAN EZ200)
in Lead/Lag Arrangement
Starting Point:
1 Total Feed Flow Rate, Feed Composition, and Direction of Flow, Inlet
Operating Temperature, And Inlet Operating Pressure:
Total Feed Flow Rate (kmol/hr): 7535
Total Feed Flow Rate (Nm3
/hr): 168889
Feed Composition (mol%):
Hydrogen
Nitrogen
Carbon Monoxide
Carbon Dioxide
Methane
Argon
Water
TOTAL
21.980
6.210
44.170
3.200
0.010
0.050
24.380
100.000
Direction of Flow: Downflow
C): 220
2 Inlet H2S and COS Levels:
H2S (ppmv as S): 6.5*
COS (ppmv as S): 0.0*
*These values are the equilibrium values of the COS Hydrolysis reaction.
3 Client Requirements (All Cases):
Required Guaranteed Absorbent Life per Bed (VULCAN EZ200)
(months):
6
(Assumed)
Required Guaranteed Maximum Exit Total S Level (ppmv,
expressed as S):
0.1
Required Expected Maximum Total Catalyst Bed Pressure Drop
across H2S Removal Section after 1 Year (bar):
Unknown

4 Results:
The Absorbent Bed Pressure Drops:
Calculated Required Bed Volume of VULCAN EZ200 per
Reactor (m
3
):
64.6* (Order:
133 for 2
reactors)
Absorbent Bed Diameter D (m): 4.35
Absorbent Bed Height H (m): 4.35
H/D (-): 1.0
Guaranteed Minimum Bed Life per Absorbent Bed (VULCAN
EZ200) for the Calculated Required Bed Volume (months):
8.5**
Guaranteed Maximum Exit Total S Level (ppmv): 0.1
Calculated Total Expected Absorbent Bed Pressure Drop for
2 VULCAN EZ200 Reactors after 1 Year (bar)***:
0.304
*This Bed Volume is determined by the minimum acceptable contact time of 25 s.
**It is assumed that the sulfur slip from the first bed is allowed to increase to 90%
of their inlet levels.
***These absorbents will be changed after 6 months.

ISOTHERMAL SWEET SHIFT SECTION: Alternative Approach
Simulation Input Data
1 Enthalpy method: 0 (Ideal gas)
2 Cases considered:
Case 1A: Standard Case, 0 years expected (SOR).
Case 1B: Standard Case, 2 years guaranteed = 4 years expected (EOR).
Case 2A: Lower Inlet Operating Pressure, 0 years expected (SOR).
Case 2B: Lower Inlet Operating Pressure, 2 years guaranteed = 4 years
expected (EOR).
Case 3A: Addition of 100 kmol/h N2, 0 years expected (SOR).
Case 3B: Addition of 100 kmol/h N2, 2 years guaranteed = 4 years expected
(EOR).
3 Feed stream data
Cases 2A and
2B: Lower Inlet
Operating
Pressure
Case 3A and
3B: Case
Addition of 100
kmol/h N2
Cases 1A and
1B: Standard
Case
Inlet Temperature (oC): 210
Inlet Pressure (bara): 25.2 33.2 33.2
Inlet CO (kmol/h): 3325.3 3325.3 3325.3
Inlet CO2
(kmol/h): 184.7 184.7 184.7
Inlet H2 (kmol/h): 1654.1 1654.1 1654.1
Inlet N2 (kmol/h): 466.9 566.9 466.9
Inlet CH4
(kmol/h): 1.4 1.4 1.4
Inlet H2
O (kmol/h): 8685.7 8685.7 8685.7
Inlet Ar (kmol/h): 2.9 2.9 2.9
TOTAL (kmol/h, wet): 14321.0 14421.0 14321.0
Inlet CO (mol%, wet}: 23.220 23.059 23.220
Inlet CO2
(mol%, wet}: 1.290 1.281 1.290
Inlet H2 (mol%, wet}: 11.550 11.470 11.550
Inlet N2 (mol%, wet}: 3.260 3.931 3.260
Inlet CH4
(mol%, wet}: 0.010 0.010 0.010
Inlet H2
O (mol%, wet}: 60.650 60.229 60.650
Inlet Ar (mol%, wet}: 0.020 0.020 0.020
TOTAL (mol%, wet}: 100.000 100.000 100.000

4 Kinetics
PROPRIETARY
5 Catalyst
PROPRIETARY
6 Catalyst Activity relative to standard
PROPRIETARY
7 Catalyst size and packing details
Default values were used.
8 Catalyst pressure drop parameters
PROPRIETARY (No pressure drop could be calculated, because reactor
geometry is unknown).
9 Catalyst Volume
A typical GHSV of 5000 Nh-1
(wet) was assumed, which with a maximum
Total Wet Inlet Flow Rate of 14421 kmol/h = 323232 Nm3
/h, results in a
Catalyst Bed Volume of 64.6 m3
(Order: 66.5 m3
).
10 Standard die-off rate
PROPRIETARY
11 BFW Rate
A value of 300.000 t/h was assumed. This is much higher than the default
value, because the process flow rates are very high. The Client provided
no value.
12 Vapor fraction: 0
13 Steam Temperature = 220o
C.
The value is lower than the default value of 250o
C, because we need to
avoid excessive process temperatures in the catalyst bed.
14 Steam Pressure.
A Steam Pressure of 23.201 bara was used, which is the Saturated Steam
Pressure at 220o
C.

15 Boiling Model: The default value
PROPRIETARY
16 Volumetric UA:
0.03 MW/(m3K). this value is higher than the default value of 0.02
MW/(m3
K), because we need to avoid excessive process temperatures in
the catalyst bed.

Isothermal Shift Simulations Results
Table 1: Exit Composition (kmol/h):
Case 1A Case 1B Case 2A Case 2B Case 3A Case 3B
CO 22.9 35.8 22.9 38.4 22.9 35.6
CO2 3487.1 3474.2 3487.1 3471.6 3487.1 3474.4
H2 4956.5 4943.6 4956.5 4941.0 4956.5 4943.8
N2 466.9 466.9 466.9 466.9 566.9 566.9
CH4 1.4 1.4 1.4 1.4 1.4 1.4
H2O 5383.3 5396.2 5383.3 5398.8 5383.3 5396.0
Ar 2.9 2.9 2.9 2.9 2.9 2.9
TOTAL 14321.0 14321.0 14321.0 14321.0 14421.0 14421.0
Table 2: Required Catalyst Type, Required Catalyst Bed Volume, Expected
Approach-to-Equilibrium (WGS Reaction) and CO Slip:
Required
Catalyst
Type:
PROPRIETARY VULCAN SERIES CATALYST
Required
Catalyst Bed
Volume (m3
):
64.6 (Order: 66.5)
ATE (o
C): 1.0 22.5 1.2 26.2 1.0 22.2
CO Slip
(mol%, dry):
0.26 0.40 0.26 0.43 0.25 0.39
Table 3: Maximum Catalyst Bed Temperature and Position:
Maximum
Bed
Temperature
(o
C):
298.8 300.5 296.8 298.4 298.4 300.0
Position
(Catalyst Bed
Volume m
3
):
8.7 44.8 8.7 44.8 8.7 44.9

Comments:
• We can guarantee that the CO Slip after 2 years will always be less than
the value indicated by the Client (= 1.2 mol% (dry)). We could perhaps at
a later stage even offer a smaller catalyst volume. The CO profile found in
the worst case (Case 2b) suggests that we could go as low as 55 m3
.
• Catalyst Life: 2 years guaranteed.
• Catalyst Bed Pressure: At this stage it is impossible to calculate the
pressure drop, because we know nothing about the geometry of this multi-
tube reactor.
• There is very little difference in performance between the 3 Cases.

APPENDIX

(AGRU) ACID GAS SOUR SHIFT: CASE STUDY IN REFINERY GAS TREATMENT

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