Novel Landfill-Gas-to-Biomethane Route Using a Gas–Liquid Membrane Contactor for Decarbonation/Desulfurization and Selexol Absorption for Siloxane Removal

• Published in: Processes 2024-08, Vol.12 (8), p.1667
• Main Authors: da Cunha, Guilherme Pereira, de Medeiros, José Luiz, Araújo, Ofélia de Queiroz F.
• Format: Article
• Language: English
• Subjects: Absorption; Adiabatic; Alternative energy sources; Batteries; Biogas; Carbon dioxide; Compressibility; Compressibility effects; Contactors; Decarbonation; Desulfurization; Desulfurizing; Electricity generation; Emissions; Enhanced oil recovery; Fault detection; Fugacity; Gas absorption; Gases; Gravity; Heat transfer; Hollow fiber membranes; Hydrogen sulfide; Industrial design; Landfill; Landfill gas; Liquid membranes; Methane; Modularity; Partial differential equations; Siloxanes; Solvents; Steady state models; Strippers; Troubleshooting
• ISSN: 2227-9717; 2227-9717
• DOI: 10.3390/pr12081667

A new landfill-gas-to-biomethane process prescribing decarbonation/desulfurization via gas–liquid membrane contactors and siloxane absorption using Selexol are presented in this study. Firstly, an extension for an HYSYS simulator was developed as a steady-state gas–liquid contactor model featuring: (a) a hollow-fiber membrane contactor for countercurrent/parallel contacts; (b) liquid/vapor mass/energy/momentum balances; (c) CO2/H2S/CH4/water fugacity-driven bidirectional transmembrane transfers; (d) temperature changes from transmembrane heat/mass transfers, phase change, and compressibility effects; and (e) external heat transfer. Secondly, contactor batteries using a countercurrent contact and parallel contact were simulated for selective landfill-gas decarbonation/desulfurization with water. Several separation methods were applied in the new process: (a) a water solvent gas–liquid contactor battery for adiabatic landfill-gas decarbonation/desulfurization; (b) water regeneration via high-pressure strippers, reducing the compression power for CO2 exportation; and (c) siloxane absorption with Selexol. The results show that the usual isothermal/isobaric contactor simplification is unrealistic at industrial scales. The process converts water-saturated landfill-gas (CH4 = 55.7%mol, CO2 = 40%mol, H2S = 150 ppm-mol, and Siloxanes = 2.14 ppm-mol) to biomethane with specifications of CH4MIN = 85%mol, CO2MAX = 3%mol, H2SMAX = 10 mg/Nm3, and SiloxanesMAX = 0.03 mg/Nm3. This work demonstrates that the new model can be validated with bench-scale literature data and used in industrial-scale batteries with the same hydrodynamics. Once calibrated, the model becomes economically valuable since it can: (i) predict industrial contactor battery performance under scale-up/scale-down conditions; (ii) detect process faults, membrane leakages, and wetting; and (iii) be used for process troubleshooting.