Technique Analysis On The Biomass Gasification Syngas Fermentation To Produce Ethanol

The process of syngas fermentation to produce ethanol integrates two kinds of craft advantages of thermal chemical process and biological fermentation process, focused on by more and more people.The main technology process is as follows: biomass is converted into high temperature crude synthesis gas by gasification, then put into fermentation tank after cooled and cleanup by removing tar and dust, and the synthesis gas is converted into low concentration of ethanol by fermentation. Azeotropic concentration ethanol is recycled by distillation, waste gas from tank and the high temperature and high pressure steam produced by cooling synthesis gas are put into electricity and steam cogeneration equipment, part of the steam supplying ethanol distillation process.Based on principle of biomass gasification, characteristic of Aspen plus software and mechanism of the syngas fermentation theory, this paper establishes the models and optimization of biomass gasification> synthesis gas fermentation、 differential pressure distillation of the ethanol recovery and co-generation power simulation, and then calculates and analysis the whole process.The simulation values of biomass gasification model is agree with literature value, while the values of syngas fermentation is not closely coincided, but can roughly estimate of ethanol yield. In addition, the oxygen and water vapor-oxygen as gasification agent are respectively studied, finding that agent addition amount influences the gasification products and ethanol production. Furthermore, the oxygen as gasification agent produces more ethanol than water vapor-oxygen, and when the mass ratio of oxygen to dry biomass is0.4, ethanol yield reaches the largest.This paper uses oxygen as gasification agent, O2/B is0.4.This paper uses differential pressure distillation process by twin towers to recycle ethanol of fermentation tank; Also conducts heat integration to recover the condensing heat of the rectifying tower; Moreover, optimizes the the operation parameters of reflux ratio and tower pressures of the toping tower to get the minimum total energy consumption:as the ethanol concentration of the fermentation tank is2.4%, and parameters ofr、P1and P2are1.25、0.35atm and1.8atm respectively, the minimum energy consumption is48966.88kW, and Distillation production consumes4.90tons of0.4MPa low-pressure steam; as the ethanol concentration of the fermentation tank is5.0%, and parameters of r、P1and P2are0.25、0.35atm and1.8atm respectively, the minimum energy consumption is56906.49kW, and Distillation production consumes2.78tons of0.4MPa low pressure steam.In addition, this paper also establishes two simplified models of the cogeneration technology process which the main parts are single waste heat boiler, steam turbine and M701F gas turbine, waste heat boiler, steam turbine respectly.Then calculate output power of two different components of the waste gas.When the waste gas calorific value is higher, the gas and steam turbine cogeneration technology can recover more heat; when waste gas calorific value is lower, boiler steam cogeneration technology is chosen to simulate calculation.Comprehensive above simulation models, the models conduct a rigid material balance and energy utilization calculation about this process.The result is that as the capacity of2000tons per day and syngas conversion ratios are under lower and higher situations, ethanol yield of155kg per ton biomass and319kg per ton biomass can be acquired; units of energy utilization efficiency is37.77%and45.12%respectly.