| A steady-state model of a countercurrent, updraft, biomass gasifier was developed and verified against pilot-plant data. The experimental data was obtained from a medium scale pilot plant. The gasifier was modeled in two parts: a combustion-gasification (CG) and a pyrolysis model. Development of the CG model demonstrated that the combustion reaction was mass transfer controlled, and the water-gas shift reaction was approximately at equilibrium. The CG model was studied for sensitivity to the particle diameter, air-to-steam ratio, oxygen mass transfer coefficient and the chemical reaction activation energies. The pyrolysis model was based on assuming the pyrolysis reaction was heat transfer limited. Linearized results for a moving-boundary, phase-change model were used to develop the rate of the pyrolysis process. |
