生物质组分及温度对闪速热解挥发分的影响

Effects of chemical components and temperature on the volatility of biomass in flash pyrolysis

A laminar flow furnace reactor heated by a plasma jet was designed to study the influences of the biomass components, pyrolysis temperature and residence time on the volatility of biomass materials at flash heating rate and isothermal pyrolysis conditions. The plasma can provide with a high heating rate over 104K·s^-1 to meet the experimental requirement of this work. Flash pyrolysis experiments of coconut shell, cotton stalk and rice husk were conducted in the laminar flow furnace reactor at the temperatures of 750K, 800K, 850K, 900K, and with the gas passing distance of 0.2m, 0.25m, 0.3m and 0.35m, respectively. Using the ash as the tracer, the mass percentage of volatile products were obtained. The tests of three models by regression analysis on the experimental data employing statistics software were done to validate the models. The regression results show that the “S” model fits the data well. Compared with the theoretical analysis of the first-order kinetic Arrhenius model, it is found that the “S” model has the same expression as the first-order kinetic Arrhenius model . Thus the first-order kinetic Arrhenius model can be used to simulate the pyrolysis process and predict the percentage of volatile products during flash pyrolysis. The researches indicate that the biomass components, pyrolysis temperature and residence time have great influence on the mass volatile fraction of biomass flash pyrolysis. The mass volatile fraction grows with pyrolysis temperature and residence time. The mass volatile fraction as a function of pyrolysis temperature and residence time in the form of Arrhenius is determined. The volatile products are mainly produced by the pyrolysis of cellulose and hemicellulose, while the char is mainly formed by the pyrolysis of lignin. Therefore, the biomass material with high content of cellulose and hemicellulose would have high volatile yield.