The influence of pressure and temperature on coal pyrolysis/gasification

Abstract

AbstractThe aim of the study is mainly to understand the effect of pressure and temperature on the property of coal particles in pyrolysis/gasification. The pyrolysis of Shenfu (SF) coal sample and the gasification of resultant char were carried out in a thermogravimetric analyzer (TGA) under pressurized and ambient conditions. The gas released from coal pyrolysis was analyzed using a portable FTIR spectrometer connected to the TGA. Simultaneously, the surface structure and main chemical compounds of the pyrolyzed char particles were analyzed using gas sorption (ASAP2020), CNHS, etc. analysis instruments. First, the pyrolysis of SF coals was carried out in a pressurized TGA at various pressures (0.1, 0.8, 1.5, 3 and 5 Mpa) with a heating rate of 10 °C min−1 and a final temperature of 1000 °C. It was observed that higher pressures accelerated the devolatilization of coal samples at lower temperatures (<500 °C), while the maximum mass loss rate was reduced, and the solid char yield increased with increasing pressure. The specific surface area and chemical components changed with changing system pressure. The gasification reactivity of the solid char particles obtained was analyzed using ambient thermal balance at 1000 °C, using CO2 as the gasifying agent. The gasification reactivity increased with increasing pyrolysis pressure. Then the pyrolysis of SF coal was carried out under different temperatures (500, 650, 800 and 1000 °C) at ambient and higher pressures (3 Mpa). With increasing temperature, the gas product from coal pyrolysis enhanced greatly at the expense of decreasing charcoal residue. The surface area of the char particles obtained were minimum at 800 °C (ambient pressure) and at 600 °C (3 Mpa). The gasification reactivity of solid charcoal residues decreased considerably with increasing pyrolysis temperature at ambient pressure, while at 3 Mpa a different result was obtained, with the highest gasification reactivity at 800 °C. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.