Air gasification of rice husk in a dual distributor type fluidized bed gasifier

In this study, a dual distributor type fluidized bed gasifier was used for the air gasification of rice husk in view of producing fuel gas. The effects of varying fluidization velocity (0.22, 0.28 and 0.33 m s(-1)) and equivalence ratio (0.25, 0.30 and 0.35) on the gasifier performance were discussed. The steady state temperature varied between 665 and 830 degrees C. The fluidization velocity of 0.22 m s(-1) and equivalence ratio of 0.25 appeared to be the optimum conditions with respect to the quality of gas. The mole fractions of the combustible components reached their maximum values at these conditions with a typical gas composition of 4% H-2, 5% hydrocarbons (CH4, C2H2, C2H4 and C2H6), 15% CO2, 20% CO and 57% N-2. The higher heating value of the gas obtained at these fluidization velocity and equivalence ratio (3.09-5.03 MJ Nm(-3)) compared very well with published data from air-blown biomass gasifiers of similar scale of operation. The gas yield and carbon conversion were in the range of 1.30 to 1.98 Nm(3) kg(-1) and 55.0 to 81.0%, respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.