Experimental studies on gasification of agricultural residues in a fluidized bed

Abstract

Gasification is one of the primary thermo chemical conversion methods to convert biomass into valuable, energy rich, fuel gas. Biomass is widely considered to be a potential fuel and renewable resource for the future. Energy from biomass is a more attention worldwide because it is a potentially CO2 - neutral and renewable energy source. Gasi cation of biomass has been denied a possible system for producing renewable hydrogen, which is bene cial to exploit biomass resources, to develop a highly efficient clean way for large-scale hydrogen production, and has less dependence on insecure fossil energy sources. Agricultural residues (AR) are readily available but not utilized in energy recovery schemes particularly in developing countries. In the present study, a fluidized bed biomass gasifier system has been fabricated to investigate the utilization of agricultural residues and saw dust. The system consisted of steam generator, fluidized bed gasifier, cyclone, water scrubber, dry filter, thermocouples and microprocessor based control unit and gas analyzer. The gasification was carried out in a fluidized bed with the samples of coconut shell (CS), groundnut shell (GS), rice husk (RH), and saw dust (SD) with air and steam as fluidization and gasification agents respectively. The carbon, hydrogen, oxygen and nitrogen percentage were found by elemental analysis, the volatile matter, fixed carbon and moisture content were found by the proximate analysis. Experiments performed in the fluidized bed gasifier were carried out in two groups for all the samples. At first, the effect of the temperature (650 to 950ºC) was determined on gas composition, gas yield, lower heating value (LHV) and carbon conversion efficiency at a constant biomass feed rate and equivalence ratio. The second group of experiments was performed in order to determine the effect of steam to biomass ratio (0 to 1.0) on the gas composition, gas yield, gas lower heating value (LHV) and carbon conversion efficiency.