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October 5, 2010 October 5, 2010

Biomass GasificationA Brief Review for Instituto Petroquimica ArgentinaBiomass GasificationA Brief Review for Instituto Petroquimica Argentina

William L. TittleWilliam L. Tittle Raul Arias AlvarezRaul Arias AlvarezPrincipal and Director of StrategyAmericas and AsiaPrincipal and Director of StrategyAmericas and Asia

Senior Consultant and ManagerLatin AmericaSenior Consultant and ManagerLatin America

Table of Contents

• A definition of biomass gasificationg• Why biomass gasification?• Relationship to other biomass utilization processes• Biomass availability• Biomass availability• Food versus fuel debate• Technology issues

Biomass Gasification October 5, 2010

What is biomass gasification?gBiomass gasification is the process of converting an organically

derived, carbonaceous feedstock by partial oxidation to make a gaseous product, known as synthesis gas,” which consists primarily of hydrogen (H2) and carbon monoxide (CO), with lesser amounts of carbon dioxide (CO2), water (H2O), methane (CH ) higher hydrocarbons (C +) and nitrogen (N ) These(CH4), higher hydrocarbons (C2+), and nitrogen (N2). These reactions are generally conducted at elevated temperatures, 500 to 1,400°C (930 to 2,550°F), and at atmospheric or higher pressures up to about 33 bar (480 psia) The oxidant used forpressures, up to about 33 bar (480 psia). The oxidant used for the partial oxidation can be air, pure oxygen, steam or a mixture of these gaseous materials. Air-based gasifiers typically make a gas with a relatively high nitrogen yp y g y g gconcentration and with a low heating value, generally between 4 and 6 MJ/m3 (107 to 161 Btu per ft3). Oxygen-based and steam-blown gasifiers make gas products containing relatively


high concentrations of H2 and CO, and with heating values between 10 and 20 MJ per m3 (268 to 537 Btu per ft3).

Why biomass gasification?y g• Feedstocks and products are fungible with the existing fuels and

chemicals• Can use mixed feeds

• Bioprocessing use enzymes that are typically sensitive to feedstocks, pretreatment, poisoning, and operating conditions

• Achieving scale does create logistical challenges with bioprocessing, but biomass can be pre-pyrolyzed (torrefaction) in the field as the first step in biomass gasification for shipment, storage, and feeding as a more energy-dense and easily handled bio-oil or charmore energy dense and easily handled bio oil or char

• Downstream processing technologies are similar to conventional processing:• Material handling, gasification, syngas treating, catalytics synfuelMaterial handling, gasification, syngas treating, catalytics synfuel

production• Same feedstock can make a range of fuels and chemicals


Biomass gasification versus other strategies for conversion to fuels and chemicals

Cellulosic biomass fermentation to ethanol or butanolNon-food natural oil sources for conversion to FAME or other diesel-range biofuels – including castor and jatropha beans, and oil-bearing algaeConversion of cellulosic biomass to levulinic acid, which is catalytically hydrogenated to methyl-tetrahydrofuran (MTHF), a high-octane cosolvent for ethanol and natural gas liquids blending (called P-Series fuel)Pyrolysis of lignocellulosic biomass to bio-oils, with catalytic upgrading to motor fuelsGasifying biomass of all kinds to produce syngas for either diesel or gasoline-range fuels, along with heat and power, and chemicals


Biomass availability

U.S. Biomass Inventory Total approximately I billion tons per year Total approximately I billion tons per year

Urban Waste3%

Forest13%

Perennial Crops35%

Manure4%

Grains5%5%

Crop Residues8%

Soy Stalks/HullsCorn Stover

20%Wheat Straw

6%

Soy Stalks/Hulls6%

Sourc e: U.S . DOE/USDA 2005 Report - Biomas s as Feedstock for Bioenergy and Bioproducts Industry : T he Techn ica l Feas ib ility of a Billion-Ton Annual Supply


Q208_ 00101.000 7.4110-Figures.xls\F2.2

p y y pp y

Direct versus indirect biomass gasification?g• Direct biomass gasification is similar to coal gasification• Indirect biomass gasification is similar to both steam methane g

reforming and coal gasification• Similar solids handling and ash removal to coal gasification• In making syngas for methanol production by biomassIn making syngas for methanol production by biomass

gasification, introduction of nitrogen from air would be a liability. Therefore, an indirect heat transfer system is required from the combustion fraction of the feed that qsupplies the process heat to the biomass that is to be pyrolyzed


Biomass gasification involves technologies that have been known for decades. The novel elements are:

Mechanics of feeding biomass, other than pre-pyrolyzing it to feed it as liquids, gases, char, and/or slurries, which is well-knownNew air separation technologies for oxygen-blown gasifiers (developed for coal gasification IGCC, but adaptable to bi )biomass)New catalysts for converting syngas to liquids, chemicals, or hydrogen, or for treating pyrolysis liquids New syngas cleanup techniquesNew microbes for fermentation of biomass gasification syngas to alcohols or hydrocarbons


Types of direct biomass gasifiers:

Air-blown direct – heat of reaction is provided by partial combustion of biomass Oxygen-blown direct - heat of reaction is provided by partial combustion of biomass, but with higher energy because the nitrogen diluent is eliminated Fixed Bed:Counter current updraft - Solid moves down, gas moves upConcurrent - Solid and gas move in same directiong

• Downdraft - solid and gas move down• Updraft- solid and gas move up

Cross current Solid moves down gas moves at right anglesCross-current - Solid moves down, gas moves at right anglesVariations:

• Stirred bed


• Two-stage gasifier.

Types of direct biomass gasifiers (continued):

Fluidized Bed:Single reactor - Low gas velocity, inert solid stays in reactor.Fast fluid bed - Inert solid is elutriated with product gas and recycledCirculating bed - Inert solid is elutriated, separated and C cu at g bed e t so d s e ut ated, sepa ated a drecirculated; sometimes also referred to as fast fluidized bed or twin-reactor systems.Entrained bed - Usually no inert solid; highest gas velocity of y ; g g ylean-phase systems; can be run as a cyclonic reactorTwin reactor – Steam gasification and/or pyrolysis occur in the first reactor, char is burned in the second reactor to heat the ,fluidized medium for recirculation; either can be any type of fluidized bed, although the combustor is often a bubbling fluidized bed.


Types of direct biomass gasifiers (continued):

Moving Bed :Mechanical transport of solids contact; careful design needed to avoid solids carryover.OtherRotary kiln - Good gas-solid contact; careful design needed to ota y Good gas so d co tact; ca e u des g eeded toavoid solids carryoverCyclonic reactors - High particle velocities give high reaction rates; similar to fast fluid bed reactors;


Product distributions from the different modes of pyrolysis pyrolysis

Typical Phase Yields from Pyrolysis Modes

Mode Conditions Liquid Char Gas

y y(Percent yields, dry wood basis)

Fast pyrolysis Moderate temperature, short residence time, particularly vapor 75 12 13Carbonization Low temperature, very long residence time 30 35 35oGasification High temperature, low residence times 5 10 85


Schematic of the Gasification-Pyrolysis Continuum


Typical functional groups contained in bio-oils from various biomass sources.

Typical Functional Group Content in Bio-Oils

Feedstock Carbonyl 1 Carbonyl 2 Hydroxyl Phenolic Methoxyl

Maple 2.1 5.7 0.92 2.8 2.1

Wheat Straw 1.4 5.3 1.40 3.0 1.1

Polar-Aspen 2.1 6.2 0.77 2.8 1.6

Peat Moss 1.2 3.0 1.30 1.8 0.7Peat Moss 1.2 3.0 1.30 1.8 0.7

Source: Resource Transforms International Ltd.,


Process Schematic - CHOREN Syngas Production from Biomassfrom Biomass

Syngasto

Fischer-

wash water

TropschProcess


BCT - Pulse EnhancedTM Indirect Gasification System Features:

High quality, medium calorific value syngasCustomized syngas composition for downstream processing Feedstock flexibilityEnergy self-reliant for the proprietary PulseEnhancedTM heat exchangersPulseEnhanced heat exchangersInherently stable and safeBCT’s system can be described as steam reforming gasification which has the following distinguishinggasification, which has the following distinguishing characteristics:– At an elevated temperature carbon will strip oxygen from

water to form carbon monoxide and hydrogenwater to form carbon monoxide and hydrogen– The endothermic operation uses roughly 20 percent of the

heating value of the fuel for the process



Product gases are hydrogen and carbon monoxide with small amounts of methane, suitable for reforming to alcohols and/or synthetic natural gas BCT’s patented Pyrolytic Steam Reforming Gasifier (PSRG) features a Staged Temperature Reaction Process (STRP),

hi h i l i d d l hi h B fwhich is claimed to produce a clean high-Btu syngas from a variety of biomass feeds. A unique feature claimed for the BCT system is that the cyclones and water condenser are integrated and contained within the biomass gasification chamber Thisand contained within the biomass gasification chamber. This design is said to conserve space and reduce the loss of heat energy.It is claimed that the First Stage Devolatilization Reactor:It is claimed that the First Stage Devolatilization Reactor: – Forces out the oxygen entrained with feedstock– In a reducing environment, raises the temperature of the

f d t k i th f di ti t t t j t b l


feedstock in three or four distinct stages to just below combustion temperature


Releases the volatiles (VOCs), which makes their energy available for subsequent reforming or energy productionAvoids the production of excess heat, CO2 and other combustion productsEliminates “flash pyrolysis” and “run away” combustionEliminates slag and reduces ash productionIt is further claimed that the Second Stage Reforming Reactor with entrained flow design that combines feedstock (char) with g ( )superheated steam at 1,500ºF, results in:– Lower operating temperatures within a controlled

environment– Lower soot production partly due to lower maximum

temperatures and partly due to higher steam-carbon ratio, which reduces soot production


p


Lower emissions: when steam is added as a gasification agent, the H2 content is increased and the CO2 content is lowered. This, it is claimed, results in faster combustion and lower emissions of CO and NOxThe Integrated Gas Cleanup and Conditioning, it is claimed,

d l l i h i l lk liproduces ultra clean syngas with no particulates, tar, or alkali metals, and low NOx, SOx, and CO2.


Food versus fuel debate is raised with biomass gasificationg

Food prices are driven by economic growth and biomass gasification applications are focused on marginal landThe value of grain in a box of typical breakfast cereal is only about 1 percent of the price of the price of the cereal box in a grocery storeGasification is targeted at switchgrass and other


October 5, 2010 October 5, 2010

Biomass GasificationBiomass Gasification

William L. TittleWilliam L. Tittle Raúl Arias ÁlvarezRaúl Arias ÁlvarezPrincipal and Director of StrategyAmericas and AsiaPrincipal and Director of StrategyAmericas and Asia

Senior Consultant and ManagerLatin AmericaSenior Consultant and ManagerLatin America

october 5, 2010 - · pdf fileoctober 5, 2010 biomass gasification ... • same feedstock...

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