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A small scale (~270 Nm3·h−1) vacuum pressure swing adsorption (VPSA) air separation system was established in Qinghai Province (in China) with an altitude of 3800 m, which was used to supply oxygen for relieving the hypoxia. The effects of adsorption and desorption time, purge and pressure equalization step and feed temperature on the performance of the process were investigated by performing experiments under plateau special conditions. Results showed that pressure equalization and intermittent purge steps could effectively improve the performance of the VPSA process. The system could produce 270 Nm3·h−1 of 90% O2 with 62.6% oxygen recovery from compressed air. The maximum productivity and minimum energy consumption with pressure ratio of 160:42 for ~90% O2 were 121.7 L·h−1·kg−1 and 0.55 kWh·Nm−3, respectively. [ABSTRACT FROM AUTHOR]

Pressure swing adsorption (PSA) is a suitable method to enrich the concentration of methane in coal mine methane (CMM) separation processes. However, traditional PSA processes for low-concentration CMM can easily increase the concentration of methane to explosive limits, which subsequently increases the risk of explosion. In this paper, a novel PSA process for low-concentration CMM was studied. Using a mixture of activated carbon (AC) and carbon molecular sieve (CMS) as the adsorbent, this method ensures that the gaseous mixture adsorbed does not reach the explosive limits by adsorbing methane and part of the oxygen simultaneously. Using a two-bed vacuum PSA experimental apparatus, the low-concentration CMM was safely enriched from 20% to more than 30%, with CMS and AC mass ratio of 3.4. The results of experimental studies indicate that the mixture adsorbent (AC and CMS) has explosion-suppression and flameproof characteristics. The igniting resource (methane) will not explode even if it appears in the adsorbent layer and, in addition, the explosion will not propagate through the adsorbent layer if it happens in other areas. [ABSTRACT FROM AUTHOR]

Abstract: In order to solve hypoxic problems in high altitude area and ensure workers life safety, a new cycle named as Low Pressure Swing Adsorption for oxygen concentration was proposed. In this cycle, the high efficiency liking Vacuum Pressure Swing Adsorption was obtained but the vacuum was not used. The relationship between oxygen concentration and oxygen flux was revealed. And the matching air content curve in different altitudes was acquired. Basing on the experiment data, the life safety system with oxygen supplied for workers was suggested. After using this system, the oxygen partial pressure of the tunnel face could be enhanced by 2 – 3kPa and the incidence of AMS in the workers decreased significantly, blood oxygen saturation increased, pulse rate and breaths per minute decreased. [Copyright &y& Elsevier]