Field test of large-scale hydrogen manufacturing from underground coal gasification (UCG)

The paper explores the reliability of using an underground coal gasification (UCG) technique for hydrogen manufacturing. Methods for increasing the temperature in underground gasifier are analyzed with the aim of improving the hydrogen-manufacturing process. In this paper, the rationales behind hydrogen manufacturing in UCG is explained. The experimental conditions and process of the underground gasification in Woniushan Mine, Xuzhou, Jiangsu Province are introduced, and the experimental results are analyzed. By adopting the new method of two-stage UCG with long channel and big section, the daily water gas production reaches about 16,000 m3, with a maximum output of 46,000 m3, with H2H2 content between 40% and 73%, and both CO and CH4CH4 contents over 6%. The daily average output of H2H2 is 7680m3. Experimental results show that the two-stage underground gasification with multi-point air (steam) feed cannot only improve the average temperature of the gasifier effectively, but also shorten the cyclical time of the two stages by a wide margin, which increases the time when water gas with a high content of H2H2 is produced by 0.95–1.24 times and 1.2–1.7 times respectively, as opposed to that of the conventional mode of pumping air (seam) with fixed points for field and model tests. Furthermore, the experimental data indicate that the backward gasification can form new temperature conditions and increase the gasification efficiency of coal seams and the productivity of hydrogen, which proves the feasibility of UCG for large-scale H2H2 production.