Impact of Bed Length on Low-Concentration Coal Mine Methane Enrichment by Proportion Pressure Swing Adsorption

Abstract

The enrichment and utilization of low-concentration coal bed methane (LCCMM) will provide a fuel source, will ensure safety from flammable gas release and will prevent significant greenhouse gas emissions. One of the special challenges in dealing with LCCMM originates from the presence of O 2 , which is difficult to process economically and explodes easily. In this work, we studied oxygen-bearing LCCMM with a CH 4 concentration of 20% and developed a safe and effective enrichment method for LCCMM: Proportion Pressure Swing Adsorption (PPSA), which used a mixture of active carbon (AC) and carbon molecular sieves (CMS) as adsorbents. With this method, CH 4 and O 2 in LCCMM can be adsorbed simultaneously because CH 4 is mostly adsorbed by active carbon and O 2 is mostly adsorbed by the CMS. Therefore, the concentration of CH 4 and O 2 is well controlled and does not exceed the explosive limit during the adsorption and desorption processes. The impact of bed length on LCCMM by PPSA was investigated. We have demonstrated the safety and feasibility of PPSA for obtaining 30% CH 4 from LCCMM, with 20% CH 4 in air as a feed stock. Our results showed that the O 2 concentration can be controlled well and does not exceed the explosive limit in both adsorption and desorption, and the CH 4 concentration in the desorption gas can be increased to more than 30% by adjusting the bed length and mass ratio of the AC and CMS.

High performance and low temperature coal mine gas sensor activated by UV-irradiation

“…Coal mining is considered much more hazardous than hard rock mining. Incident reports show that the presence of minor amount (about 1–3%) of CMM in the underground mines atmospheres causes increasing the explosion risk to about 75% 3 , 4 . Hence, timely gas detection in underground mines and rapid ventilation is essential for coal miner safety 5 .…”