(189j) Optimization of a Dual PSA Process for the Separation of Mixture Gas Consisting of Methane and Carbon Dioxide

Heavy products of PSA processes are not the waste anymore to developers and designers. Reducing the cost for raw materials and obtaining reusable waste gas are main issues for industrial efficiencies in these days. In a methane and carbon dioxide separation system, because the carbon dioxide is main component of the heavy product of a methane PSA processes, the recycling or collection of the heavy product is even more important issue. For that reason, Dual-PSA process is suggested by Grande at al., 2012. This system has two units which called Rectifying unit and Stripping unit. Whereas the rectifying unit is similar to the stand-alone methane PSA unit, the stripping unit has a role of re-separation of heavy products to upgrade the purity of carbon dioxide. Each unit has two columns of which adsorbent is one of carbon molecular sieve (CMS) and follows 4-step general Skarstrom cycle. The optimization for each unit is fulfilled individually, and the objective is the maximizing methane recovery for rectifying unit and the maximizing carbon dioxide recovery for stripping unit. After the optimization, the methane recovery in light product is improved to 97.5% from 80% with same purity, 97%, and the carbon dioxide purity increases from 43.0% to 75.7% whereas the recovery slightly decreases from 86.0% to 85.5%. Above all, the most outstanding result is that it is possible to obtain high purity carbon dioxide while having a similar recovery to a stand-alone methane PSA process.