Model development and energy and exergy analysis of the biomass gasification process (Based on the various biomass sources)

Worldwide growing demand for energy consumption in recent years arising from industrialization development and increasing earth population has caused more environmental concerns to emerge. On the other hand, specific issues related to the use of fossil fuels as a nonrenewable source of energy has been caused alternative fuels like biomass to be investigated with more concern. Generally, gasification is a process which converts organic matter to gas and tar. Also, through the gasification, biomass as a fuel is converted to the combustible gas (syngas). In this study, modeling and simulation of the biomass gasification process is investigated and analyzed considering 23 different kinds of the biomass sources. The proposed model is based on the Gibbs free energy minimization and the restricted equilibrium method is used for calibration. The process operating performance is analyzed thermodynamically based on the hydrogen production yield. In this regard, effective parameters like temperature of the gasification, air-fuel ratio, steam-biomass ratio and temperature of the air and steam streams are investigated. Gasification temperature and steam-biomass ratio affect the syngas compositions and the heating value significantly. Biomass moisture has the most significant impact on the syngas production efficiency. Also, other parameters which are not very intensive but still have an effect on the syngas production efficiency, are examined. Finally, the process performance is analyzed based on the energy and exergy analysis methods. The obtained results show that, exergy efficiency of drying stage is the highest (about 90.0%) in all cases. Nonetheless, exergy destruction rate for this stage is a great value against the others. Among the selected biomasses, Rice husk type has the greatest exergy destruction rate which is related to the tar combustion and decomposition reactors; respectively.