Characteristics of Temperature Field during the Oxygen-enriched Underground Coal Gasification in Steep Seams

Abstract

Through the underground coal gasification model test in steep coal seams, the changing characteristics and effects of pure oxygen gasification, oxygen-steam gasification, moving-point gasification, backward gasification methods on the underground gasification process, and gas quality were discussed. Experiments showed that, under the pure oxygen gasification, the rising rate for the roof temperature of the coal seams to be gasified is about 3.13°C/h, with that of the floor about 1.06°C/h; in the forward oxygen-enriched steam gasification stage, the high temperature field mainly concentrates around the gasification gallery, and the highest temperature in the oxidation zone reaches above 1,200°C. According to the experimental data, when the steam/oxygen ratio stood at 2:1, gas compositions remained virtually stable and CO + H2 was basically between 58 and 72%. Gasification with moving points can obviously improve the temperature conditions in the gasifier. Compared with forward gasification, the average temperature in the gasifier for backward gasification is lower than that of the former.