The Process Study Of Producing Low-carbon Alcohol From Biomass Synthesis Gas

In the program of alternatives to oil, biomass conversion to liquid transportation fuels is one direction of the development of alternative energy, while producing low-carbon alcohol from biomass synthesis gas is one of the better conversion path in this direction.In the process of producing low-carbon alcohol from biomass synthesis gas, something should be noted:the selection of biomass gasification way; the selection of alcohol synthesis catalyst and the selectivity of alcohol synthetic products, etc.There are three parts in this paper. First of all, through the process of biomass synthesis gas to low-carbon alcohol, this part introduces the source of synthesis gas and the process of gasification. Then, the process of alcohol from synthesis gas and the alcohol synthesis catalyst are introduced, especially the alcohol synthesis catalyst. In the end, the thermodynamics, dynamics and the reaction mechanism of the process of low-carbon alcohol from synthesis gas are elaborated.And on that basis, the model of low-carbon alcohol from biomass synthesis gas is established using the process simulation software Aspen. The process involves feed handling and drying, gasification, gas cleanup and conditioning, and the synthesis and refining of alcohol. The following impacts are considered in this model:CO conversion in water gas shift, reform fractions of recycle synthesis gas, tar reform, some parts methanol recycle. The unit of acid gases removed and air separation unit are added. The overall mass and energy balance is calculated. The model analysis shows:in order to meet the requirements of synthesis gas H2/CO molar ratio for the whole process, the optional process condition is obtained, that is, the reform fraction of recycle synthesis gas is between0.4-0.6, the CO conversion ratio is between0.01-0.1; CO conversion is significant impact on the whole process; lower the content of methane, more the yield of alcohol in the process; improved the conversion ratio of tar reformer is good for synthesis alcohols; the yield of alcohols is proportional to reform fractions of methanol; the utilization of energy should be improved.In order to study the process of low-carbon alcohol from biomass synthesis gas, GTI gasifier’s model, BCL gasifier’s model and synthesis low-carbon alcohol models, in these study the processes of two pairs models are main compared. In the contract of the two gasifier’s models, it is found that:the content of CO2is higher and the H2, CO content is lower in the products of GTI gasifier; steam, is not only as the fluidization medium, but also as part of high temperature reaction; the content of coke from gasification is high carbon and low sulfur; compared BCL gasifier, the utilization of C in GTI gasifier is improve, but there is still much room for improvement. In the contract of synthesis low-carbon alcohol models, it is found that: the simulate results are in good agreement with the literature data; water should be effectively removed in the process; compared the process synthesis low-carbon alcohol by BCL gasifier, the form of carbon transformation by GTI gasifier is similar, and there is still much room for improvement both of them; the conversion efficiency of ethanol and other low-carbon alcohols is lower by GTI gasifier, and the improve room is much more than by BCL gasifier.In order to improve the utilization rate of biomass and the economical efficiency of the whole process, cogeneration natural gas model and heat and power model were established. three feasible cases are considered in cogeneration natural gas model. Overall, the model of equipment added after gas cleanup and conditioning is the best of all, because it isn’t affect methane reforming, and the methane content of tower is low. In the heat and power model, it can be obtained26811.72kW through integrated its own energy. In this process, three wastes emissions are reduced. Besides, it is good for environmental protection, and the process economy could be improved.