Pyrolysis and Combustion Behavior of Coal Gangue in O2/CO2 and O2/N2 Mixtures Using Thermogravimetric Analysis and a Drop Tube Furnace

Abstract

Combustion of coal gangue is extensively used for power generation in China. In this paper, pyrolysis and combustion characteristics of a low-rank coal gangue have been investigated under oxy-fuel (O2/CO2) and air (N2/O2) conditions using a drop tube furnace and thermogravimetric analysis. Pyrolysis experiments were carried out in N2 and CO2 environments, which are the main diluting gases of air and oxy-fuel environments, respectively. The burnout and yields of volatile matter were analyzed during DTF experiments. At lower temperatures, the weight loss rate of coal gangue during pyrolysis in N2 was higher than that in CO2. However, further weight loss took place in CO2 atmosphere at temperatures above 800 °C due to CO2 gasification of chars. The thermogravimetric analysis (TGA) results confirmed that the pyrolysis in CO2 environment can be divided into three stages: moisture release, devolatilization, and char gasification by CO2 in a higher temperature zone. Combustion experiments were carried out in fou...