Performance analysis of a pressure swing adsorption unit in removing biogas impurities using zeolite 13X

Abstract

This study aims to assess the performance of a Pressure Swing Adsorption (PSA) unit in removing the carbon dioxide from biogas by evaluating the breakthrough and adsorption capacity of the adsorption process as well as determining the effects of cyclic regeneration of the adsorbent. The PSA system developed and composed only a main vessel made up of 316 stainless steel components. It was then operated up to 10 bars pressure at ambient temperatures and gas flows at a rate from 0 to 15 L min-1. Use of physical adsorbent (zeolite 13X) will consume the gaseous impurities such as CO2. Product gas was collected into 1 L Tedlar bags and analyzed using SRI gas chromatograph with TCD and HID detector to validate the CO2 and CH4 composition. The results of the pressure swing adsorption (PSA) experiments showed an average increase of 160% in the net heating value over that of a certified gas standard. The amount of methane was also significantly higher although the amount of the other gasses (i.e. nitrogen) remained comparatively the same. The number of other gases was significantly lower and leaving no traces of carbon dioxide was observed in the PSA system product gas indicating that carbon dioxide had been completely adsorbed by the system. This study greatly helps to reduce CO2 emitted to the atmosphere from the anaerobic co-digestion of biogas to produce high energy content bio-methane fuel.