Development of coal mine methane concentration technology for reduction of greenhouse gas emissions

In coal mines in such countries as China and Russia, most of the coal mine methane (CMM) generated during mining is emitted to the atmosphere without any effective usage, because the methane concentration of CMM is relatively low and not allowed to be used as fuel for safety reasons. Methane is one of the greenhouse gases. Therefore, if it becomes possible to concentrate CMM to an acceptable level for use as fuel, this will greatly contribute to reduction of greenhouse gas emissions. With the aim of gaining approval as a greenhouse gas emission reduction of the clean development mechanism (CDM) or joint implementation (JI) project, we developed a CMM concentration system to apply the vacuum pressure swing adsorption (VPSA) technology using a high methane-selective adsorbent by Osaka Gas Co., Ltd. The pilot-scale plant of a CMM concentration system was installed in a coal mine in Fuxin City in the northeastern China and a demonstration test was commenced in December 2008. As the result, the pilot-scale plant successfully concentrated the raw material gas with a methane concentration of 21% and a flow rate of 1000 Nm3/h to 48%, which exceeded the target of the methane concentration performance (a 25% increase). The methane recovery rate reached 93%.