Experimental study and static numerical optimization of scalable design of non-adiabatic and non-isothermal pressure swing adsorption for biogas upgrading

Biogas upgrading to fuel grid quality standards using plate PSA design mediated by raw biomass adsorbent under non-adiabatic and non-isothermal conditions was tested and optimized. The interaction effects of system pressure, CO2 concentration, and adsorption/desorption time on bioCH4 purity in the product line and CO2 purity in the waste line were investigated utilizing a central composite design. The response surface methodology and desirability function were applied to specify the optimum points of the factors to maximize the two responses namely bioCH4 and CO2 purity. The generated quadratic model with experimental error of less than 5% revealed that the factors influenced both responses remarkably. The optimum conditions for bioCH4 purity within 0.95–1 desirability scale were CO2 concentration below 50%, system pressure from 1.7 bar to 3 bar, and adsorption time below 5.9 min. For CO2 purity in the waste line, the optimum conditions were CO2 concentration above 65%, system pressure higher than 2.5 bar, and desorption time of 6 min. With these ranges of conditions, the proposed system achieved bioCH4 purity of ≥ 97% and CO2 purity of ≥ 90%. © 2022 Elsevier Ltd