Technological aspects for underground coal gasification in steeply inclined thin coal seams at Zhongliangshan coal mine in China

In order to recover the abandoned coal resource of steeply inclined thin coal seams (SITCS), a field trial of underground coal gasification (UCG) with shaft method has been successfully carried out at Zhongliangshan coal mine in China. Many technological measures have been taken according to the geological conditions of coal seams. These technologies include the hollow-bottom and wall-style gasifiers, pinnate-pattern boreholes, the controlled moving multipoint gas injection, multi-component oxygen-rich gasification agent, and micro-seismic detection of flame working face. Some of the technologies were used for monitoring and controlling the UCG process, including gas-producing conditions and gasifier running states. The trial results show that it's feasible to recover the abandoned coal resource and produce clean gas energy. The gaseous product of gasification consists of 5-10% H-2, 14-16% CO and 5-8% CH4 and generated at a flow rate of 1400-1600 Nm(3)/h with a heat value of 1200-1400 kcal/Nm(3). (C) 2016 Elsevier Ltd. All rights reserved.