Modeling and Comparative Thermal Performance Analysis of a Biomass Gasifier Using Different Gasifying Agents

Abstract

This paper focuses on the modeling of a fixed bed biomass gasifier using different gasifying agents (air and steam) considering sawdust as feedstock. Both energetic and exergetic approaches are considered for analyzing the performance of the gasifier model. Performance of the modeled gasifier is evaluated via several parameters like lower heating value (LHV) of syngas, concentration of hydrogen, cold gas efficiency and exergetic efficiency considering process parameters viz., gasification temperatures, steam-to-biomass ratio (STBM) and equivalence ratio (ER). STBM is considered to be the key input parameter for steam gasification whereas equivalence ratio for air gasification. Modeled gas data has been validated with reported experimental work and it is noted that the simulated results are synchronizing well with the experimental gas data. Additionally parametric optimization shows that the maximum concentration of hydrogen is found to be 64.2% at STBM of 2.0 and 29.94% at equivalence ratio of 0.2. The maximum value of cold gas efficiency is found to be 90.4% and 83.78% at STBM of 0.8 and equivalence ratio of 0.2 respectively when the gasification temperature is 1000 °C. The maximum value of exergetic efficiency is found to be 85.4% at STBM of 0.8 and gasification temperature of 1000 °C.