STUDY ON KINETICS OF BIOMASS PYROLYSIS IN THE FIXED BED. 2. ANALYSIS OF THE RESULTS OF CALCULATING THE THERMAL DECOMPOSITION OF DIFFERENT TYPES OF SOLID FUEL

Abstract

Using the constructed non-stationary model of the dynamics of the release of volatile substances in a fixed bed [1], extensive numerical studies on three types of biomass pyrolysis Wood Birch, Wood quebracho and Bagasse were performed in order to determine the light gas composition satisfactorily coinciding with experimental data. As a result of research, the following composition of light gas (in mass fractions) was determined for the first time: CO = 0.464, CO2 = 0.101, H2 = 0.01, H2O = 0.23, C6H6.2O0.2 = 0.058, and C1.16H4 = 0.137, which differs from the light gas composition given in modern sources copies [2−4] (in mass fractions): CO = 0.396, CO2 = 0.209, H2 = 0.019, H2O = 0.249, and C6H6.2O0.2 = 0.127 [3], also CO = 0.46, CO2 = 0.08, H2 = 0.015, H2O = 0.23, C6H6.2O0.2 = 0.058, and CH4 = 0.157 [2]. Obtained calculation results for Wood quebracho with refined composition of light gas in terms of dry mass at a temperature of 800 °С: H2 = 15.56 %, CO2 = 7.134 %, CO = 51.4 %, C1.16H4 = 23.71 % (CH4 = 16.6 %, C2H4 = 7.46 %), and C6H6.2O0.2 = 2.21 % — agree satisfactorily with the experimental data. At the exit from the retort, mixed pyrolysis gas composition changes little over time and differs in the values of the gas components from the pyrolysis gases compositions obtained in the elementary volumes of the retort. This discrepancy is explained by the fact that the initial gas mixture contains components obtained at low temperatures with a high content of H2 and CO2 and a low concentration of CO and C1.16H4. Bibl. 20, Fig. 11, Tab. 4.