Biomass Gasification Biomass Gasification in ain a

Fluidized Bed ReactorFluidized Bed Reactor

NaderNader MahinpeyMahinpey, Malcolm Wilson, Malcolm WilsonUniversity of Regina, Energy University of Regina, Energy INetINet

Energy INetEnergy INet

Goal is to act as a facilitator in developing Goal is to act as a facilitator in developing research and demonstration projects.research and demonstration projects.To build capacity, research and To build capacity, research and intellectual.intellectual.To develop consortia to accomplish the To develop consortia to accomplish the above in an effective way.above in an effective way.www.energyinet.comwww.energyinet.com

University of ReginaUniversity of Regina

Building expertise and capacity in a variety Building expertise and capacity in a variety of capture and storage areas:of capture and storage areas:

Geological storage of CO2Geological storage of CO2Capture of CO2 from flue gasesCapture of CO2 from flue gasesRisk assessment, performance assessmentRisk assessment, performance assessmentGasification Gasification –– biomass and mixed fuelsbiomass and mixed fuelsHydrogen productionHydrogen production

Lab-Scale Gasifier

Fluidized Bed Reactor in U of RFluidized Bed Reactor in U of R

w/steam onGasificati

dioxide w/carbon onGasificati

w/oxygenonGasificati

cEndothermi 22HC

cEndothermi 22

COC

exothermic Highly 22O C

Exothermic 221

HCOO

CO

CO

COOC

++

+

+

+

⎯→⎯

⎯→⎯

⎯→⎯

⎯→⎯

exothermic Highly 2423HCO

Exothermic Midly 222HCO

Exothermic 422HC

nMethanatio

shift gas- Water

w/hydrogenonGasificati

OHCH

COHO

CH

++

++

+

⎯→⎯

⎯→⎯

⎯→⎯

Experimental DesignExperimental DesignFeed: Wheat Straw (Davidson)Feed: Wheat Straw (Davidson)Particle diameter: 2 mmParticle diameter: 2 mmGasification agent: air & steamGasification agent: air & steamTemperature: 800Temperature: 800ººCCPressure: 1 Pressure: 1 atmatmNo inert bed material (fluidized by itself)No inert bed material (fluidized by itself)

IssuesIssuesBedBed--agglomerationagglomerationSinteringSinteringFouling and corrosionFouling and corrosionTar formationTar formationEntrainment & ElutriationEntrainment & ElutriationInfluence of particle sizeInfluence of particle sizeEmissions: Particulate, Emissions: Particulate, NONOxx, , SOSOxx, Unburned , Unburned hydrocarbons, Halogen compounds (HCI), Alkali hydrocarbons, Halogen compounds (HCI), Alkali metal compounds (metal compounds (NaCINaCI, , NaOHNaOH. KCI, KOH). KCI, KOH)

Objectives Objectives Experimental: measuring the composition of product Experimental: measuring the composition of product gas and finding the influence of steam/air ratio, gas and finding the influence of steam/air ratio, feed/air ratio on the amount of hydrogen productionfeed/air ratio on the amount of hydrogen production, , heat transfer study (Film, Singleheat transfer study (Film, Single--particle, Emulsion particle, Emulsion phase/packet model, Kinetic model), effects of phase/packet model, Kinetic model), effects of operating conditions on heat transfer coefficientsoperating conditions on heat transfer coefficients

Simulation : Kinetics (Different models i.e.,uniformSimulation : Kinetics (Different models i.e.,uniform--reaction model, Shrinkingreaction model, Shrinking--core model), mass core model), mass transfer studies (homogeneous bed approach, transfer studies (homogeneous bed approach, bubbling bed approach), Hydrodynamicsbubbling bed approach), Hydrodynamics

Kinetics SimulationKinetics Simulation

Aspen Plus Software ProgramAspen Plus Software Program

Solid FractionSolid Fraction

ReactorsReactors

RYIELDRYIELDYield distribution data available

Unknown reaction stochiometry and kinetics

Devolatilization

RSTOICRSTOICUnknown or unimportant reaction

kinetic Known stochiometry

volatile combustion

RCSTRRCSTRKnown reaction kinetic CSTR reactors

User supplied kinetics subroutine when solids, such as char, are participating in the reactions

Char combustion

SimulationSimulationAspen Plus Aspen Plus

Main Reactions of GasificationMain Reactions of Gasification

Heterogeneous reactions Heterogeneous reactions

( ) ( ) CO12CO122O C 2−+−→+ φφφ

2HCOO2HC +→+

4CH22HC →+

2CO2COC →+

Main Reactions of Gasification Main Reactions of Gasification (Cont(Cont……))

HomogeneousHomogeneous reactionsreactions

O2HO2H 221 →+

2H2COO2HCO +→+

2COOCO 221 →+

OHCH3HCO 242 +→+

Hydrodynamic simulationHydrodynamic simulation

Fluent software programFluent software program

ObjectivesObjectives

2D and 3D modeling and simulation of the 2D and 3D modeling and simulation of the gasifier fluid dynamics in bubbling flow gasifier fluid dynamics in bubbling flow regime and comparison of the results with regime and comparison of the results with available experimental data using Fluent available experimental data using Fluent CFD package.CFD package.Utilizing a UDF (user defined function) for Utilizing a UDF (user defined function) for gasification reactions and comparison of gasification reactions and comparison of the results with experimental data.the results with experimental data.

2D and 3D Modeling2D and 3D Modeling

Bed ExpansionBed Expansion

0 s 0.1 s 0.2 s 0.3 s 0.5 s 1 s 2 s 3 s 4 s 6 s 8 s 10 s

Expanded Bed HeightExpanded Bed Height

( )( )

126.0937.0*

376.0006.1738.0*4.211

⎟⎟⎠

⎞⎜⎜⎝

⎛

−+=

agmf

PPmf

mf

f

ppwU

dUUHH ρ

Empirical FormulasEmpirical Formulas UUmfmf** HHff (m)(m)

0.070.07 0.6040.604

Hf(2D simulation)=0.63

Hf (3D simulation) =0.62

2D Error=4% over estimates for model

3D Error = 2.7% over estimated for model

Pressure FluctuationPressure Fluctuation

Volume Fraction of solidVolume Fraction of solid

Next Phase (Short term)Next Phase (Short term)

CoCo--gasification of wheat straw and other gasification of wheat straw and other waste biomass, also biomass and coal. waste biomass, also biomass and coal. Potential for mixed low grade fuels (pet. Potential for mixed low grade fuels (pet. coke, coal, bitumen).coke, coal, bitumen).