Study on Pressurized Isothermal Pyrolysis Characteristics of Low-Rank Coal in a Pressurized Micro-Fluidized Bed Reaction Analyzer

Abstract

The development of clean coal technology has prompted the study of pressurized pyrolysis for coal. Most of the existing studies are non-isothermal kinetic experiments conducted in P-TGA, which cannot reflect the particle movement in actual furnace, so there is a lack of relevant data on pressurized isothermal pyrolysis characteristics. In this work, the effects of pressure on the characteristics of gas release and pressurized isothermal pyrolysis kinetics are explored in P-MBFRA. This work finds that the yields of CO2, CO, CH4, and H2 increases with temperature and pressure. The most probable mechanism function of CO2, CO and CH4 change from shrinking core model to homogeneous model at 1MPa, 0.8MPa and 0.5MPa, respectively, showing that reaction is controlled by chemistry under low pressure but affected by diffusion effect with elevating pressure. The rate constant and activation energy of each gas appear an increasing-decreasing tendency and the difference between activation energy of each gas reduces with pressure. Compared with non-isothermal experiments, the activation energy and pre-exponential factor in P-MBFRA are less than those in P-TGA, indicating P-MBFRA can effectively reduce the diffusion inhibition, and the kinetics obtained is close to the reaction in industrial fluidized bed reactor.