Gasification characteristics of biomass/coal mixture in an ICFB reactor

Abstract

In present study, thermochemical characteristics of biomass and biomass/coal blend were determined during pyrolysis and gasification process. Sawdust, rice husk, peanut shell, gingko nut shell and Jatropha seed shell were chosen as a resource of lignocellulosic biomass. From thermogravimetric analysis, thermochemical characteristics of these biomass samples were determined, as well as cellulose and lignin which are the main component of biomass at a given linear heating rate. There are big differences between cellulose and lignin thermal behavior during pyrolysis. Cellulose was decomposed within relatively low and very narrow temperature range with higher devolatilization rate. However, lignin was decomposed within very broad temperature range from 200 ℃ to 900 ℃ with very low devolatilization rate. It is attributed to the structural differences between cellulose and lignin. From biomass pyrolysis, it can be classified into 3 stages, and each stage is mainly corresponding hemicellulose, cellulose and lignin in order of temperature range where one of the main components was mainly decomposed. Since each sample has different contents of cellulose, hemicellulose and lignin, one showed the different thermal behavior at each stage. In other words, weight loss at each stage is linearly proportional to the content of component corresponding to that stage in samples. In addition, interactions among the main components of biomass are not appeared. As the heating rate increases, the range of the degradation temperature of samples become relatively narrow and several adjacent peaks are united to form overlapped broader and higher peaks due to simultaneous decomposition of main components of biomass. As a result, from a thermo balance reactor which heat up sample within very few seconds, decomposition reaction of Jatropha seed shell is shown like only one reaction. Kinetic analysis of Jatropha seed shell was conducted by using a thermo balance reactor under isothermal cond...