Performance Prediction of Gasification of Biomass Briquettes Using Thermodynamic Equilibrium Model

Abstract

The gasification of biomass resources is considered a promising route for the production of clean energy fuels for the future.The product gas of partial combustion of biomass with air as the gasifying medium is the mixture of CO, H2, CH4, CO2, H2Oand N2 called syngas. Syngas generation is now considered matured and acceptable technology compared to other biomassconversion technologies. In this study, a thermodynamic equilibrium model to determine syngas composition based on carbon,hydrogen and oxygen obtained from composite agricultural wastes was developed. For these materials, at preset gasificationtemperature of 750oC, the effects of changes in moisture content and air/fuel ratio on the quality syngas composition weremodeled. The yields of combustible gases (H2, CO and CH4) from Rice husk briquette were observed to be generally higherthan those of groundnut shell with sawdust briquette. The result with Groundnut shell and Sawdust briquette as input indicatedthat the fraction of H2, CO and CH4 gradually decreased, while the concentration of CO2 and H2O increased when moisturecontent increases from 0% to 45%. Similar trend was observed from the analysis of Rice husk briquette gasification in the model.The amount of Air per kmol of fuel varied from 0 to 1.0. As a result, the H2, CO and CH4 content of syngas for Groundnutshell and sawdust briquette decreased continuously; with CH4 approaching zero at air/fuel ratio of unity. Similar trend occurredin Rice husk briquette, but the values were higher than those observed for the groundnut shell & sawdust briquette. The amountof CO2 and H2O increased from 14.9742% and 20.6603% to 36.5886% and 57.3208% respectively for Groundnut shell briquette,while for Rice husk briquette the amount of CO2 and H2O rose from initial values of 2.8047% and 2.2552% at zero air/fuelratios to 40.3272% and 45.6339% respectively.The results of this study would be useful for the engineering development of biomass gasification power generation technologiesand in the selection of appropriate feedstock.