08 Gasification & Liquid Fuel Synthesis

John Jechura – [email protected]: January 4, 2015

Gasification & Liquid Fuel Synthesis

Topics

• Principles of gasification

Gasification vs. combustion

• Gasifier & associated process configurations

• Products from syngas

Fisher‐Tropsch (FT) Synthesis

2

Thermochemical Conversions

• Pyrolysis Thermal conversion (destruction) of organics in the absence of oxygen

In the biomass community, this commonly refers to lower temperature thermal processes producing liquids as the primary product

Possibility of chemical and food byproducts

• Gasification Thermal conversion of organic materials at elevated temperature and reducing conditions to produce primarily permanent gases, with char, water, & condensables as minor products

Primary categories are partial oxidation and indirect heating

4

Distinction between produced gas

• Town Gas

Gas produced from coal, about 50% hydrogen, 3%‐6% carbon monoxide, & the rest mostly methane & carbon dioxide

• Synthesis Gas (Syngas)

Mixture of hydrogen & carbon monoxide

• Synthetic Natural Gas (SNG)

Mixture of mostly methane from syngas

• Producer Gas

Partial oxidation of coke with humidified air

• Water Gas

50/50 mixture of hydrogen & carbon monoxide

5

Principles of Gasification

Gasification Purification Low Btu GasCO, H2, N2

Feed

AirSteam

Contaminants

Gasification Purification Medium Btu GasCO, H2

Feed

OxygenSteam

Contaminants

Gasification Purification Medium Btu GasCO, H2

Feed

HeatSteam

Contaminants

Hydro-Gasification Purification High Btu GasCO, H2, CH4

Feed

HeatHydrogen

Contaminants

Catalytic Gasification Purification & Separation SNGCH4

Feed

Steam

Contaminants

6

Simplistic view of gasification

Biomass Gasification: Fundamentals & ApplicationsAshwani Gupta, webinar, December 7, 2010.

7

Stoichiometric Considerations

2 2

2

2 2 2

C O CO1

C O CO21

H O H O2

• Oxygen consumed (exothermic)

• Water‐gas reactions (endothermic)

• Bourdourd reaction (endothermic)

• Hydro‐gasification

• Water‐gas shift reaction

• Methanation reaction

2 2

2 2 2

C H O CO HC 2H O CO 2H

2C CO 2CO

2 4C 2H CH

2 2 2CO H O H CO

2 4 21 1

C H O CH CO2 2

8

Gasification vs. Combustion


9

Gasification vs. Combustion


10

Coal is not the only feedstock


11

Alcohol Synthesis

Biomass

Flue Gas

Dryer

Scrubber

Sludge(Waste)

CO2

Sulfur

Acid Gas Cleanup

Air

Gasifier

Solids(Waste)

Steam

Alcohol Separation

Methanol & Water

Ethanol

MixedAlcohols

Steam

Reformer

Air

Compressor

Water to recycle

Compressor

Example Thermochemical Conversion

Personal communication Ryan Davis, NREL. November 2009.

13

Gasifier configurations –Counter‐Current Moving Bed

http://www.netl.doe.gov/technologies/coalpower/turbines/refshelf/handbook/1.2.1.pdf

14

Gasifier configurations – Fluidized Bed


15

Gasifier configurations – Entrained Flow


16

Direct vs. Indirect Gasification

http://www1.eere.energy.gov/ba/pba/pdfs/bio_gasification.pdf

17

SilvaGas Indirect Gasifier

http://rentechinc.com/silvaGas.php

18

Gas Cleanup Technologies

• Particulate removal

Cyclones

Wet scrubbing

• Gas conditioning

Tar removal /destruction

CO2 & H2S removal

• Solvent systems – amines, Selexol, …

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IGCC – Integrated Gasification Combined Cycle

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Syngas Products

• Hydrogen

• Methanol and its derivatives (NH3, DME, MTBE formaldehyde, acetic acid, MTG, MOGD, TIGAS)

• Fischer Tropsch Liquids

• Ethanol

• Mixed alcohols

• Olefins

• Oxosynthesis

• IsosynthesisSyngasCO + H2

Methanol

H2OWGSPurify

H2N2 over Fe/FeO

(K2O, Al2O3, CaO)NH3

Cu/ZnOIsosynthesis

ThO2 or ZrO2

i-C4

Alkali-doped

ZnO/Cr2 O3

Cu/ZnO; Cu/ZnO/Al2 O3

CuO/CoO/Al2 O3

MoS2

MixedAlcohols

Oxosynthesis

HCo(CO)4

HCo(CO)3 P(Bu3 )

Rh(CO)(PPh3 )3

AldehydesAlcohols

Fischer-Tropsch

Fe, C

o, R

u

WaxesDiesel

OlefinsGasoline

Ethanol

Co, Rh

FormaldehydeAg

DME

Al2O

3

zeolites

MTOMTG

OlefinsGasoline

MTBEAcetic Acid

carb

onyla

tion

CH3O

H +

COCo

, Rh,

Ni

M100M85DMFC

Direct Use

hom

olog

atio

nCo

isob

utyl

ene

acid

ic io

n ex

chan

ge22

Fischer‐Tropsch for Liquid Fuel Synthesis

2 2 2 22 1 H CO C H H On nn n n

• Set of reactions that “recreates” linear alkanes from syngas

• Distribution of compounds well described by Anderson‐Schulz‐Flory distribution

where representschain growth probability

2 1n 1 nnW

23


• Chain growth probability shifts from light products to wax

24


• History

Original process commercialized in Germany in 1936. Used by Germany & Japan during World War II to produce substitute fuels

Sasol. Largest scale implementation series of plants operated by Sasol in South Africa. Required during time of apartheid.

Shell Middle Distillate Synthesis. 12,000 barrels per day Shell facility converts natural gas into low‐sulfur diesel fuels and food‐grade wax in Bintulu, Malaysia.

Ras Laffan, Qatar. Based on the Sasol technology, using cobalt catalysts at 230oC. Includes "Dolphin Gas Project" plant, converting natural gas to petroleum liquids at a rate of 140,000 barrels/day, with additional production of 120,000 barrels of oil equivalent in natural gas liquids and ethane. Was scheduled to commission in 2010.

Rentech. • Demonstration F‐T plant Commerce City, CO. Commercial scale facilities had been planned for Rialto, CA, & Natchez, MS.

• Abanded projects 2012. Sold technology in 2013.

Three GTL facilities proposed in US: Lake Charles, LA (large scale); Karns City, PA; Ashtabula, OH• December 2013 Shell cancelled plans for another facility in LA because of high capital costs & market uncertainties for natural gas & liquid product prices

25

Fischer‐Tropsch Process Considerations

• Catalyst types HTFT (High‐Temperature Fischer‐Tropsch)

• Iron‐based catalyst• 330oC‐350oC• Used extensively by Sasol in their Coal‐to‐Liquid (CTL) plants

LTFT (Low‐Temperature Fischer‐Tropsch)• cobalt based catalyst• 250oC or less• Shell’s integrated Gas‐to‐Liquid (GTL) plant in Bintulu, Malaysia.

• Product types Predominantly straight‐chain alkanes. Lesser amounts of 1‐alkenes & alcohols. Properties best for distillate fuels (jet, diesel) & wax

• Low octane gasoline. Isomerization required• May hydrocrack was for increased fuel production

26

Fischer‐Tropsch Reactor Types

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“High quality diesel via the Fischer-Tropsch process – a review”M.E. Dry, Journal of Chemical Technology & Biotechnology, v 77, pp 43-50

Fischer‐Tropsch Chain Growth & Kinetics

• General rate expressions

For Co:

For Fe:

• Water slows down rate for iron‐based catalysts

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2H CO

2CO

rate1

p pk

b p

2

2

H CO

CO H O

ratep p

kp a p

“High quality diesel via the Fischer‐Tropsch process – a review”M.E. Dry, Journal of Chemical Technology & Biotechnology, v 77, pp 43‐50

Fischer‐Tropsch – More Than Alkanes

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Fischer‐Tropsch Process Considerations

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http://www.eia.gov/todayinenergy/detail.cfm?id=15071

Production of Diesel

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Production of Gasoline, Diesel, & Chemicals

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Documents

08 Gasification & Liquid Fuel Synthesis