01 Pretreatment

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

SynGas Seminar – Margarita – Nov 2-4,2011

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


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


Lead-Lag ReactorsRaw Natural Gas Feed

To Regeneration VentTo Regeneration Vent

RegenerationSteam


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


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


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


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


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


Hydrodesulfurization

HDMaxHDMax®® 200 200 SeriesSeries

HDMaxHDMax®® 300300 SeriesSeriesHDMaxHDMax 300 300 SeriesSeries

CoMo on Alumina


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


• 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


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


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


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


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


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


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


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


Cl Guard – ActiSorb® Cl 2

Alkali ≥ 6.5%LOI ≤ 7.0%Alumina BalanceDensity 45 lbs/ft3

0 72 k /L0.72 kg/L


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


Feed Gas Treatment



• Chloride Guard – remove HCl• Zinc Oxide Adsorb H S• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal


Zinc Oxide – ActiSorb® S 2


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


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


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)



Sulfur Adsorption

• Fresh ZnOFresh ZnO

• Surface adsorption (gas diffusion)

• Solid diffusion

• Saturated


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


Top of Bed Middle of Bed Bottom of Bed

ActiSorb® S 2 Capacity for H2SH2S

AmbientVolume Optimized

(Wgt Per

fur Pickup

Sulf




ZnO Optimization

P f l f• Performance results from:

Physical Integrity

ZnO Content – active ingredient

Density of finished product

Surface Area – better diffusion


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


% 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


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


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


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


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


Feed Gas Treatment



• Chloride Guard – remove HCl• Zinc Oxide Adsorb H2S• Zinc Oxide – Adsorb H2S• ActiSorb® G 1 – Sulfur removal


ActiSorb® G 1

HydrodesulfurizationHydrodesulfurizationHydrodesulfurizationHydrodesulfurizationand Sulfur Adsorption and Sulfur Adsorption

In a Single CatalystIn a Single CatalystIn a Single CatalystIn a Single Catalyst


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

• 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


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


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


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


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


• 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?


01 Pretreatment

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