Retrofitting Biomass Combined Heat and Power Plant for Biofuel Production

Thermochemical conversion processes of biomass, such as gasification and pyrolysis, can convert a wide range of feedstocks into liquid fuels, including forest residue, agricultural, food, and municipal solid waste. These more widely available and theoretically lower cost feedstocks make biofuel production through thermochemical pathway more cost-competitive. Furthermore, the thermochemical conversion pathway for biomass conversion could be relatively easy to integrate with the existing biomass combined heat and power plant, making it an attractive technology for the future commercialization of biofuel production through biomass. A detailed analysis was undertaken of a retrofitted biomass combined heat and power plant for biofuel production in this work. The biofuel production plant is designed to explore the polygeneration of hydrogen, biomethane, and biooil via the integration of gasification, pyrolysis, and renewable-powered electrolysis. The G-valve in the biomass circulating fluid bed plant, which is generally used for sand and char recycling, is retrofitted in the proposed system to fit the pyrolysis reaction for bio-oil production. Centering around the biomass circulating fluid bed gasifier, the system is also outfitted with a condensation and distillation process for bio-oil production, and a membrane reactor system for biomethane production. A mathematical model of the proposed biofuel production plant is established in Aspen Plus, followed by a performance investigation of the biofuel production plant under various design conditions. The limitations and opportunities of this retrofitted biomass combined heat and power plant for biofuel production are explored in this study.