Process simulation of pressureswing adsorption technology optimization based on low concentration methane enrichment
Methane enrichment is a necessary measure to develop and utilize low concentration coalbed methane.Among many separation technologies,pressure swing adsorption technology has become the most widely used technology in recent years due to its advantages of low energy consumption and low cost.In order to better realize the methane enrichment effect(purity and recovery),it is necessary to study the relationship between the adsorbent and the pressure swing adsorption process,that is,to select a suitable pressure swing adsorption process for the adsorbent.This work uses Aspen adsorption process simulation software to study two different types of adsorbents(N2 selective adsorbent MIL-100(Cr)and CH4 selective adsorbent Silicalite-1)in common and optimal vacuum pressure swing adsorption(adding buffer tank).Simulation results shows that the optimal vacuum pressure swing adsorption process can effectively improve the CH4 recovery,and MIL-100(Cr)has a significantly better recovery improvement effect compared with Silicalite-1.However,when the CH4 content of the coalbed methane is less than 30％,CH4 recovery of 100％can be achieved by using Silicalite-1 adsorbent in the optimal vacuum pressure swing adsorption process.In the actual process of enriching coalbed methane,methane purity and recovery are very important indicators.Therefore,the single cycle efficiency index is proposed to comprehensively evaluate the efficiency of the methane enrichment process.The results show that compared with the common vacuum pressure swing adsorption process,the optimal vacuum pressure swing adsorption process using MIL-100(Cr)adsorbent has a single cycle efficiency improvement of more than 30 percentage point,while that of Silicalite-1 adsorbent even slightly decline 1 percentage point.Comparative analysis shows that the common vacuum pressure swing adsorption process is suitable for Silicalite-1 adsorbent,and the optimal vacuum pressure swing adsorption process with buffer tank is more suitable for MIL-100(Cr)adsorbent.
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