A Novel VPSA Process for Ventilation Air Methane Enrichment by Active Carbon

Abstract

Enrichment of ventilation air methane(VAM) is crucial to gather acceptable concentration to utilize. In this work, the adsorption characteristics of activated carbon have been tested. A novel three-bed VPSA cycle for recovering methane from methane/nitrogen mixtures using activated carbon have been done experimentally, and the VPSA process studied contains an effluent pressurization step to improve product concentration and recovery. The VPSA process was carried out under adsorption pressure at 155 kPa abs., and desorption pressure at 20 kPa abs., feeding VAM with the methane purity of 0.2%, methane purity of 0.4% with 70% recovery was obtained at ambient temperature while 0.36% purity with 87% recovery. This process has the potential of significantly increasing the product concentration and recovery with respect to the two-bed cycle process by VPSA.

Development of Combustion Technology for Methane Emitted from Coal‐Mine Ventilation Air Systems

“…[24] By using this method, the methane concentration can be increased from 0.3 to 0.75 %a ta na dsorption pressureo f < 250 kPa;h owever, 0.2 %o fm ethanei sr etainedi nt he effluent gas.Alower adsorption pressure was utilized at ambient temperature to achievet he capture of 70 %o ft he methane from af eed of VA Mw ith an initial methane concentration of 0.2 %. [25] Alternatively,ahoneycombm onolithic carbon fiber composite (HMCFC)c an be utilizeda sa na dsorbentf or methanee nrichment. [26] It was reported that HMCFCi ncreased the adsorption capacity to double that of commercially available activated carbon material.…”

Site Trials of Ventilation Air Methane Enrichment with Two-Stage Vacuum, Temperature, and Vacuum Swing Adsorption

“…Owing to the intrinsic characteristics of ventilation air from underground coal mines, including huge volumetric flow rates (120–600 m 3 /s in typical gassy mines), dilute and variable methane concentrations (<1 vol %), high relative humidity (70–100%), and dusty environment, the mitigation and utilization of VAM have been great challenges over the last two decades. − Flow reversal reactors and lean burn gas turbines have been mainly focused to oxidize VAM as a principal fuel. − Current technologies for principal use of VAM, including thermal or catalytic combustion, chemical looping, and bioreactor can be found elsewhere . Another option is to enrich the VAM up to a certain level, which is covered in this paper, providing a supplementary fuel to the oxidation units for a self-sustainable thermal balance when the VAM concentrations are lower than the minimum operational requirement. − Also, in the course of VAM enrichment, an explosion risk needs to be eliminated or prevented by proper safety measures such as removing ignition sources, keeping CH 4 concentrations out of the explosive range (5–15 vol % CH 4 ), and keeping O 2 concentrations below 12 vol % …”

“…There exists separation technologies that can be potentially considered for VAM enrichment, including hydrate-base gas separation, , absorption into ionic liquids, , membrane separation, , and adsorption with solid adsorbents. , As of today, among these technologies, due to their technical and practical limitations, only adsorption-based processes with solid adsorbents have been applied for VAM enrichment by mainly three groups (University of Science and Technology (UST), ,,− Dalian University of Technology (DUT) in China, and CSIRO ,,, in Australia. The first two groups in China have applied a vacuum pressure swing adsorption (VPSA) process with coconut shell-derived composites, the CH 4 adsorption capacities of which at 298 K were about 0.010 and 0.910 mmol/g at 0.67 and 100 kPa, respectively.…”