Pyrolysis product distribution of the typical subbituminous coal and bituminous coal under ultra-high temperature conditions

Abstract

ABSTRACT In this work, the effect of temperature on the pyrolysis products of two typical coal samples, namely, bituminous coal and subbituminous coal, is studied by using a tube furnace with the highest working temperature of 1700°C. The temperature range is set to 1000–1400°C to obtain ultrahigh temperature conditions. Proximate analyses and ultimate analyses are performed to obtain the basic characteristics of raw coal samples. In the pyrolysis process, the tube furnace is preheated to the target temperature, prior to the coal samples and as the quartz tube being pushed into the constant temperature zone of the tube furnace. The yields and release rate of the light volatile gas (LVG), the calorific value, the distribution of LVG, and pyrolysis products are evaluated. Additionally, the impact of temperature on LVG is discussed in-depth. The amount of volatile gas increased by 1.25 and 1.38 times for ZD coal and DT coal, respectively, with increasing temperature. Our results show that increased temperature has a positive impact on the acceleration of the cracking and raises the gross output of volatile gas. The H2 yield is approximately 50–70% of LVG, and the CO2 and CO show opposite variations with temperatures due to the conversion of the oxygen atoms in the gas. The output of CH4 is inhibited due to the presence of the carbon deposition reaction in the high-temperature pyrolysis, resulting in increasing H2 yield. Additionally, the yields of char and tar decrease with increasing temperature.