Enrichment of Low-Quality Methane by Various Combinations of Vacuum and Temperature Swing Adsorption Processes

• Published in: Industrial & engineering chemistry research Vol. 61; no. 38; pp. 14298 - 14304
• Main Authors: Bae, Jun-Seok, Yu, Xin Xiang, Su, Shi
• Format: Journal Article
• Language: English
• Published: American Chemical Society 28-09-2022
• Subjects: Separations
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.2c01890

As an endeavor to reduce greenhouse gas emissions while harnessing an energy source, this paper applied various combinations of adsorption-based swing processes to enrich a wide range (3–30%) of low-quality coal mine methane (CMM) in air to a level that a direct utilization can be made by gas engine technology. Having honeycomb monolithic carbon fiber composites tuned for CMM enrichment, at least 5.3 and 3.5% CH4 were found to be required by one- and two-stage vacuum swing adsorption (VSA) processes, respectively, to obtain more than 9.0% CH4 in the product. As VSA alone, however, can give rise to a safety risk that the CH4 concentrations in the product are still in the explosive range, a one-stage vacuum, temperature, and vacuum swing adsorption (VTVSA) process was applied, enriching 3.0–8.6% CH4 up to 18.2–50.7% CH4 in the product and thus eliminating the safety concern. As a reference for other applications, 10.3–30.1% CMM streams can be enriched up to 57.5–86.9% through the one-stage VTVSA process. To minimize energy consumption with two fixed columns, VSA and VTVSA processes in the first and second columns, respectively, were applied, enriching 3.1 and 4.1% CH4 up to 31.6 and 37.3% CH4 in the product, respectively. In this paper, various adsorption-based technology options are provided for mine operators to enrich low-quality CMM and can be applied for other applications such as methane capture from abandoned landfill sites. Due to the explosive nature of the low-quality CH4 in air, this paper is the first to cover the enrichment of a wide range of low-quality CMM below 30% with an explosion-proof enrichment unit being capable of various vacuum and temperature swing adsorption processes.