01 pretreatment
TRANSCRIPT
2011 Synthesis Gas Seminar – Margarita y gFeed PretreatmentNovember 2–4, 2011
Feed Gas Treatment
P bl• Problem components
S lfHC Feed
Steam
HTS
SulfurChloridesOlefins
S SCl ClCoking
OlefinsPurification Pre Reformer Primary Reformer
Cl
CO2Reforming
SClH2
Cl
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HT CO Shift LT CO Shift CO2 Removal Methanation
Feed Gas Treatment
A ti t d C b • Activated Carbon –adsorption of H2S + organic S
• H d d lf i ti (HDS)• Hydrodesulfurization (HDS) –convert organic S to H2SC t i hl id t HClConvert organic chlorides to HCl
• Chloride Guard – remove HClZi O id Ad b H S• Zinc Oxide – Adsorb H2S
• ActiSorb® G 1 – Sulfur removal
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Activated Carbon: C8-6 / C8-77
ADVANTAGES DISADVANTAGE
• Low Cost • Capacity Affected by • Regenerable• Low Temperature
p y yHeavy Hydrocarbons
• Need for Frequent Low Temperature Operation
• Effective on Virtually
qRegeneration
• Emissions Control yall Sulfur Species during Regeneration
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Lead-Lag ReactorsRaw Natural Gas Feed
To Regeneration VentTo Regeneration Vent
RegenerationSteam
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Purified Natural Gas
Activated Carbon
A bi• Ambient temperature• Steam before initial use• Regenerate upflow with steam to vent (or hot
NG/fuel )C t l t /NG l it t t fl idi tiControl steam/NG velocity to prevent fluidization < 0.5 ft/sec (SLV)Evolution of hydrocarbons and sulfur duringEvolution of hydrocarbons and sulfur during regeneration may need to condense/capture regeneration steam and hydrocarbonsNo oxygen in steam if above 400ºF (205ºC)
• No oxygen > 200ºF (95ºC) without steam
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yg ( )• Typical sulfur leakage: < 0.1 ppm
Activated Carbon - Operation
S lf i i d d b 125 F• Sulfur capacity is reduced above 125oF • Typical operating cycle 7-14 days• Typical feeds: < 5 ppmv RSH
< 5 ppmv H2ST bl i• Troublesome contaminants:
Heavy hydrocarbons can reduce capacityCO2 ( 5 %) d i i ifi lCO2 (>5 %) can reduce capacity significantlyWater vapor can reduce capacity somewhat
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Activated Carbon - Operation
C i B R iCapacity Between RegenerationsSCF of Feed per Ft³ of C8-7
Sulfur Type ppm SCF/ft³1 3 260 0001-3 260,0003-5 130,000
H2S
1-3 260,0003-5 130,000
R-SH
COS passes throughRegen Cycle depends on
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g y pbed volume and sulfur concentration
Activated Carbon - Problems• Reduced capacity between regenerations• Reduced capacity between regenerations
Surface ContaminationIncomplete RegenerationIncomplete RegenerationHeavy Hydrocarbon Buildupo C5+ can reduce capacity 50%p yo Insufficient regeneration temperatureIncreased Inlet Sulfuro Adsorbent capacity is fixedo Cycle length is inversely proportional to S content5% CO2 can reduce capacity 50%5% CO2 can reduce capacity 50%3% H2O can reduce capacity 20-30%High inlet temperature - > 125ºF (50ºC) capacity falls off
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g p ( ) p y
Feed Gas Treatment
A ti t d C b d ti f H S d i S• Activated Carbon – adsorption of H2S and organic S• Hydrodesulfurization (HDS) –
t i S t H Sconvert organic S to H2SConvert organic chlorides to HCl
Chl id G d HCl• Chloride Guard – remove HCl• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal
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Hydrodesulfurization
HDMaxHDMax®® 200 200 SeriesSeries
HDMaxHDMax®® 300300 SeriesSeriesHDMaxHDMax 300 300 SeriesSeries
CoMo on Alumina
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NiMo on Alumina
HDMax® Catalysts® ®Catalyst HDMax® 200 HDMax® 300
Wt % CoO 4.5 ---Wt% NiO --- 4.9Wt% MoO3 18.5 20.0Alumina Balance BalanceOperating Temp ºF 450-800 450-800
ºC 230 425 230 425• Converts all S species to H2S – downstream H2S trap
C t Cl i t HCl d t HCl t
ºC 230-425 230-425
• Converts Cl species to HCl – downstream HCl trap• Hydrogenates olefins• N t ff t d b h h d b
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• Not affected by heavy hydrocarbons
HDMax® Reactions
R SH H R H H SR-SH + H2 R-H + H2SRSR’ + 2 H2 RH + R’H + H2S
RS-SR’ + 3 H2 RH + R’H + 2 H2SCOS + H2 CO + H2S
C4H4S + 4 H2 C4H10 + H2S
Chlorides R-Cl + H R-H + HClChlorides R-Cl + H2 R-H + HCl
Olefins RnH2n + H2 RnH2n+2 + HeatNeeded when > 0.5% olefinsΔT = ~15-18ºF (8-10ºC) per 1% molar
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Control ΔT with recycle or multi-bed with intercooler
HDMax® - Operation
• TemperatureMin-Max = 450-800ºF (230-425ºC)T i l 650 750ºF (345 400ºC)Typical range = 650-750ºF (345-400ºC)Limits risk of hydrocarbon cracking
• Space Velocity: 1500-6000 /hSpace Velocity: 1500 6000 /h• Sulfiding
NG with 2-10 ppmv of sulfur no sulfiding requiredNG with 2 10 ppmv of sulfur, no sulfiding requiredOlefins in the feed – must be pre-sulfided
• Hydrogen RequirementHydrogen RequirementTypical H2 = 4-7 psia (0.3-0.5 bara) Olefins H2 = stoichiometric + 5-10% excess in the effluent
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Naphtha H2 = 15-20%
Sulfiding Reactions
S lfidiSulfidingCoO + 0.11H2 + 0.89H2S CoS0.89 + H2
MoO3 + 2H2S MoS2 + 3H2O3NiO + H2 + 2H2S Ni3S2 + H2O
DesulfidingCoS0.89 + 0.89H2 Co + 0.89H2S
MoS2 + 2H2 Mo + 2H2S2 2 2
Ni3S2 + 2H2 2Ni + 2H2S
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H2S to Sulfide CoO1.00E+01
1 00E-01
1.00E+000.1 Bar H2 Partial Pressure
1 Bar H2 Partial Pressure
5 Bar H2 Partial Pressure
1 00E 03
1.00E-02
1.00E-01 10 Bar H2 Partial Pressure
1.00E-04
1.00E-03
1.00E-06
1.00E-05
1.00E-08
1.00E-07
150 200 250 300 350 400 450 500 550
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150 200 250 300 350 400 450 500 550
Temperature, oC
H2S to Sulfide NiO1.00E+03
1.00E+02
0.1 Bar H2 Partial Pressure1 Bar H2 Partial Pressure5 Bar H2 Partial Pressure10 Bar H2 Partial Pressure
1 00E+00
1.00E+01
1.00E-01
1.00E+00
1.00E-02
1.00E-04
1.00E-03
150 200 250 300 350 400 450 500 550
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150 200 250 300 350 400 450 500 550
Temperature, oC
H2S to Sulfide MoO31 00E+01
1.00E+00
1.00E+01
0.1 Bar H2 Partial Pressure1 Bar H2 Partial Pressure5 Bar H2 Partial Pressure
1.00E-02
1.00E-015 Bar H2 Partial Pressure10 Bar H2 Partial Pressure
1 00E-04
1.00E-03
1.00E-05
1.00E 04
1.00E-07
1.00E-06
150 200 250 300 350 400 450 500 550
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150 200 250 300 350 400 450 500 550
Temperature, oC
HDS Special Consideration• Cracking Potential• Cracking Potential
Carbon laydown and ΔP buildup• If sulfur is low < 2 ppm• If sulfur is low - < 2 ppm
Minimize H2 recycle – possibly < 1%Keep inlet temperature < 700ºF (370ºC)Keep inlet temperature < 700ºF (370ºC)
• No contact with air/O2 after on line or sulfidedNo contact with air/O2 after on line or sulfided
• Shutdown Maintain with inert gas (could be N2, H2, NG)If Olefins in the feed, purge with inert gas during
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shutdown
Feed Gas Treatment
A i d C b d i f H S d i• Activated Carbon – adsorption of H2S and organic S
• H d d lf i ti (HDS)• Hydrodesulfurization (HDS) –• convert organic S to H2S• Convert organic chlorides to HCl• Convert organic chlorides to HCl
• Chloride Guard – remove HCl• Zinc Oxide Adsorb H S• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal
SynGas Seminar – Margarita – Nov 2-4,2011 Page 20
Cl Guard – ActiSorb® Cl 2
Alkali ≥ 6.5%LOI ≤ 7.0%Alumina BalanceDensity 45 lbs/ft3
0 72 k /L0.72 kg/L
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ActiSorb® Cl 2
Chl id i h LTS• Chlorides are a very strong poison to the LTS• Reacts with ZnO: ZnO + 2HCl ZnCl2 + H2O
Z Cl bli 500ºF (260ºC)ZnCl2 sublimes ~500ºF (260ºC)
R i N 2O 2HCl 2N Cl H O• Reaction Na2O + 2HCl 2NaCl + H2O
• Operating Temperature = 70-850ºF (20-450ºC)• Vapor Phase or Liquid Phase• Cl pickup = 8-10% wt.• Typically a layer on top of the ActiSorb® S 2
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Feed Gas Treatment
A i d C b d i f H S d i• Activated Carbon – adsorption of H2S and organic S
• H d d lf i ti (HDS)• Hydrodesulfurization (HDS) –• convert organic S to H2S• Convert organic chlorides to HCl• Convert organic chlorides to HCl
• Chloride Guard – remove HCl• Zinc Oxide Adsorb H S• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal
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Zinc Oxide – ActiSorb® S 2
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ActiSorb® S 2
H S Z O Z S H OH2S(g) + ZnO(s) ZnS(s) + H2O(v)
• An ADSORBENT, not a catalyst• ZnO is consumed by H2S containing gas• Not regenerable• Must be replaced when it no longer adsorbs Sulfur
• Typical performance 40-60 ppbv (Zn-ZnS equilibrium)• With Pre-Reformer recommend bottom layer of
ActiSorb® 305 to achieve < 10 ppb
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Component ppmv TemperatureH2S ≤ 100 See graphH2S ≤ 100 See graph
Limited, Short-term Capacity for Organic Sulfurs
RSH / RS-SR' < 10 >600ºF (315ºC)COS < 10 >700ºF (370ºC)COS 10 700 F (370 C)RSR' < 10 >750ºF (400ºC)Thiophenes 0
• For temporary, unavoidable circumstances• If feed has organic sulfurs hydrotreat with CoMo or NiMo
Thiophenes 0
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If feed has organic sulfurs, hydrotreat with CoMo or NiMo
ActiSorb® S 2 Capacity for H2SH2S
AmbientVolume Optimized
(Wgt Per
fur Pickup
Sulf
Gas Hourly Space Velocity (V / V / h)
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Gas Hourly Space Velocity (V / V / h)
Sulfur Adsorption
• Fresh ZnOFresh ZnO
• Surface adsorption (gas diffusion)
• Solid diffusion
• Saturated
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Axial Profile of Sulfur Level
Saturated Solid Diffusion Gas Diffusion Fresh Catalyst
Saturated With Sulfur
T f B d Middl f B d B tt f B d
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Top of Bed Middle of Bed Bottom of Bed
ActiSorb® S 2 Capacity for H2SH2S
AmbientVolume Optimized
(Wgt Per
fur Pickup
Sulf
Gas Hourly Space Velocity (V / V / h)
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Gas Hourly Space Velocity (V / V / h)
ZnO Optimization
P f l f• Performance results from:
Physical Integrity
ZnO Content – active ingredient
Density of finished product
Surface Area – better diffusion
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High and Low Surface Area
5
3
4
Low Surface Area ZnO
2
3
1
00 20 40 60 80 100
High Surface Area ZnO
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% Bed
ZnO Problems• ΔP buildup• ΔP buildup
Surface contaminationo Solids in the feedo Solids in the feedo Cracking in the feed heater coilZnCl2 formationZnCl2 formationo Affects structure o At >500ºF (>260ºC) can move downstream; corrosion( )CO2 + ZnO ZnCO3 (Zinc Carbonate)o Forms rapidly 200-500ºF (95-260ºC)o Weakens the physical structureo Reduces amount of Zn available to form ZnS
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o Decomposes at >500ºF (>260ºC)
Comparing Adsorbents
ActiSorb S ZnO "C" ZnO "D"
Size 4.8 mm 4 mm 3.2 mmShape Pellets Pellets SpheresWt% ZnO 90 100 85Density, lbs/CF 78 68 78 Performance*:Wt% S Pickup 26.9 19.6 19.0S Pickup, lbs/CF 22.5 19.7 14.2
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System Design Choices – 1 Vessel
Medium / High Temperature – Single BedCobalt Moly / ZnO Hydrogenation of Sulfur to H2S
Ad• Advantages– Lowest initial cost system
Handles ALL sulfur species
RAW GAS
– Handles ALL sulfur species and not sensitive to changes
• Disadvantages
CoMo
– CoMo “Thrown” Away– Lower Capacity than a 2-bed
system
ZnO
system– Plant must shut down to change-
out PURIFIED GAS
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System Design Choices – Lead/Lag
Medium / High Temperature – Dual BedCobalt Moly / ZnO Hydrogenation of Sulfur to H2S
• AdvantagesRAW GAS • Advantages– Handles ALL sulfur species
and not sensitive to changes
RAW GAS
g– Increased Sulfur Capacity
50%Ch “O th R ”
CoMoCoMo
– Change “On the Run”• Disadvantages
– CoMo “Thrown” Away
ZnO ZnO
– CoMo Thrown Away– Increased Cost in
vessels/material
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PURIFIED GAS
System Design Choices: 3-Bed
Medium / High Temperature – 3 Bed SystemCobalt Moly / ZnO Hydrogenation of Sulfur to H2S
• Advantages• Advantages– Handles ALL sulfur species– CoMo life maximized
RAW GAS
CoMo life maximized– Increased Sulfur Capacity– Change “On the Run”ZnO ZnO
C M • Disadvantages– Highest Cost in
vessels/material
CoMo
vessels/material
PURIFIED GAS
SynGas Seminar – Margarita – Nov 2-4,2011 Page 37
Feed Gas Treatment
A i d C b d i f H S d i• Activated Carbon – adsorption of H2S and organic S
• H d d lf i ti (HDS)• Hydrodesulfurization (HDS) –• convert organic S to H2S• Convert organic chlorides to HCl• Convert organic chlorides to HCl
• Chloride Guard – remove HCl• Zinc Oxide Adsorb H2S• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal
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ActiSorb® G 1
HydrodesulfurizationHydrodesulfurizationHydrodesulfurizationHydrodesulfurizationand Sulfur Adsorption and Sulfur Adsorption
In a Single CatalystIn a Single CatalystIn a Single CatalystIn a Single Catalyst
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ActiSorb® G 1
Cu 1.5% wtMo 3.5% wtZnO BalanceSurf Area 30m²/gSurf Area 30m /gDensity 75-85 lbs/ft³
1 2 1 4 kg/L
• Same ZnO lbs/ft³ as ActiSorb® S 2 S S C it
1.2-1.4 kg/L
Same S Capacity• HDS activity even after S saturation
L ti it f Ol fi h d tiSynGas Seminar – Margarita – Nov 2-4,2011 Page 40
• Low activity for Olefin hydrogenation
System Design Choices: 1 VesselSingle Bed – Optimized use of Actisorb G-1
RAW GAS
Option 1 - Lower Cost for Same Time On-stream (no
RAW GAS
Same Time On stream (no CoMo required)
Option 2 Up to 30 50% longer
CoMo
G 1G-1 Option 2 - Up to 30-50% longer Life with fixed reactor volume (replace CoMo with G-1)
ZnOG-1G 1
PURIFIED GAS
SynGas Seminar – Margarita – Nov 2-4,2011 Page 41
System Design Choices – Lead/Lag
RAW GAS
Dual Bed – Optimized use of Actisorb G-1
O ti 1 L C t fOption 1 - Lower Cost for Same Time On-stream (no CoMo required)
CoMoCoMo
q )
Option 2 - Up to 30-50% longer Life with fixed reactor volumeG-1 G-1ZnO ZnO Life with fixed reactor volume (replace CoMo with G-1) G-
1G-
1
G-1 G-1
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PURIFIED GAS
System Design Choices: 3-Bed
3 Bed System – Actisorb G-1
EliminateRAW GAS
Eliminate The CoMo Vessel RAW GAS
ZnO ZnO
(new designs or replacement)
G-1 G-1CoMo
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PURIFIED GASPURIFIED GAS
CO2 and COS
Z O h bl i h COS d CO i h f d• ZnO has some trouble with COS and CO2 in the feedH2S + CO2 COS + H2O
• Higher CO2 means higher COS• Small amount of H2O helps – COS hydrolysis
COS + H2O CO2 + H2S
• ActiSorb® G 1 can solve the problem
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ActiSorb® G 1 and COS
Wi h C M /NiM• With CoMo/NiMoCOS + H2 H2S + CO Hydrogenation
COS + H2O H2S + CO2 Hydrolysis• Leaving equilibrium COS• In ZnO H2S + ZnO ZnS + H2O
• ActiSorb® G 1 has Hydrogenation/Hydrolysis to the bottom of the bed and continuous H2S adsorption
• As H2S concentration decreasesso does COS equilibrium
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• With H2S concentration ~50 ppb, COS eq = ~0
Feed Pretreatment
A iS b® 200/300 i lf d• ActiSorb® 200/300 to convert organic sulfur and chloride to H2S + HCl
• T HCl ith A tiS b® Cl 2 h d f Z O• Trap HCl with ActiSorb® Cl 2 ahead of ZnO• Trap H2S with ActiSorb® S 2 to 40-60 ppb
Wi h CO /COS A iS b® G 1 li i COS• With CO2/COS use ActiSorb® G 1 to eliminate COS• For a pre-reformer polish to < 10 ppb S with
A tiS b® 305ActiSorb® 305
QUESTIONS?
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