Purification and Upgrading from Biogas to Biomethane

Abstract

Biomethane could be upgraded from biogas to increase its heating value, avoid corrosion and eliminate toxicity. The simplest and most common technique for upgrading biogas is absorption process. In this study, two processes between water scrubbing and chemical scrubbing with diethanolamine (DEA) solution integrated with regeneration and recirculation are compared through Aspen Plus simulations. The aim of this study is to find the suitable operational condition in absorption process in order to increase the efficiency of the process in recovery methane and to decrease the energy consumption in the system. Our model was developed by including one additional absorber unit. Results show that the systems, both water scrubbing and chemical scrubbing, can achieve high purity of biomethane of >96 %v/v. In comparison between models for water scrubbing, our proposed system offers higher recovery methane of 4.68% of and 7,863.07 kW of energy of biomethane. In chemical scrubbing process, our system was able to decrease the pressure of absorber from 55.2 to 10 bar. Consequently, the recovery methane and energy of biomethane were increased while the energy consumption of system was decreased.