A contrast study on different gasifying agents of underground coal gasification at Huating Coal Mine

Abstract

To optimize the technological parameter of underground coal gasification (UCG), the experimental results of air gasification, air-steam gasification, oxygen-enrichment steam gasification, pure oxygen steam gasification and two-stage gasification were studied contrastively based on field trial at the Huating UCG project. The results indicate that the average low heat value of gas from air experiment is the lowest (4.1 MJ/Nm3) and the water gas from two-stage gasification experiment is the highest (10.72 MJ/Nm3). The gas productivity of air gasification is the highest and the pure oxygen steam gasification is the lowest. The gasification efficiency of air gasification, air-steam gasification, oxygen-enriched steam gasification, pure oxygen steam gasification and two-stage gasification is listed in ascending order, ranging from 69.88% to 84.81%. Described a contract study on results of a field test using steam and various levels of oxygen enrichment of 21%, 32%, 42% and 100%. The results show that, with the increasing of O2 content in gasifying agents, the gas caloricity rises, and the optimal O2 concentration range to increase the gas caloricity is 30%∼40%. Meanwhile, the consumption of O2 and steam increase, and the air consumption and steam decomposition efficiency fall.