Biogas industry: Novel acid gas removal technology using a superacid solvent. Process design, unit specification and feasibility study compared with other existing technologies

Publication date: Available online 13 December 2019Source: Chemical Engineering Research and DesignAuthor(s): Iran D. Charry Prada, Rodrigo Rivera-Tinoco, Chakib BouallouAbstractA novel purification technology for raw biogas streams is proposed and it is based on the use of a superacid solution within a bubble column reactor. The solvent is a mixture of sulfuric acid (H2SO4(aq), 95.0 wt.%) and acetic acid glacial (CH3COOH(l), ≥99.8 vol.%), both commercial grades. A mixture with a molar ratio of 9/1 for H2SO4(aq),/CH3COOH(l) respectively, leads to the interesting physical and chemical absorption properties for biogas treatment.Process simulations of the technology within a frequently used biomethane production process showed simultaneous capabilities for H2S elimination, CO2 absorption and, siloxanes and volatile organic compounds (NMVOCs) complete degradation. A single bubble column reactor was designed for treating 500 Nm3/h  of raw biogas with H2S content between 400 and 1500 ppmv (dry basis) and for handling a solvent volume flow between 10.23 and 23.39 L/min, depending on the H2S gas content. Proper functioning and hydrodynamic stability of this unit were evaluated in order to avoid possible issues related to bubbles coalescences or break-up, liquid backmixing and mass transfer limitations.Comparison of the proposed technology with methanol-based and monoethanolamine (MEA(aq))-based absorption processes allowed proving the low energy demands of the proposed un...
Source: Chemical Engineering Research and Design - Category: Chemistry Source Type: research