Techno-economical Analysis Of Cellulosic Ethanol Production Process By Different Pretreatments

Energy development and utilization is the basis of the development of human society and industrial economy. With the sustained growth of energy consumption, energy shortage has become a global challenge. Because of its advantages of green, clean and renewable, cellulosic ethanol is considered as the ideal substitute for fossil energy. However, there are serious obstacles to the development of cellulose ethanol industry, such as the lack of cellulosic ethanol industrial production process with obvious advantages at present, most of the technology development and research is still in the laboratory scale, and technology and economy research on complete process are lacking too. Therefore, this research focus on the process model of complete cellulosic ethanol production process using different pretreatment processes, and the optimization of the simulation was performed with the application of the energy integration, then a comprehensive techno-economical analysis of the process was performed. The feedstock used in this paper was corn stover due to its abundance and low cost. The specific contents are as follows:(1) Three kinds of cellulosic ethanol production process were simulated. The cellulosic ethanol production process by pretreatments of dilute sulfuric acid, ammonia fiber explosion method, liquid hot water were established with daily processing 2000 tonnes of corn stover, which include sections of pretreatment, enzymatic hydrolysis and fermentation, separation and purification, wastewater treatment, raw materials and product storage, cogeneration and utility and so on, and Aspen Plus platform was used to realized these three full process simulation. The ethanol yield of these three process simulations were 0.1661 million tonnes/year,0.1525 million tonnes/year and 0.1496 million tonnes/year; and through the optimization of the heat exchanger network, the energy recovery rate were 32.13% and 25.15% and 34.43% respectively.(2) The economic analysis and comparison of three kinds of cellulosic ethanol production processes are carried out. Firstly, detailed calculation of required equipment investment in the production process of cellulose ethanol was estimated in this paper, including the total investments and operation costs. Then the discounted cash flow analysis of cellulosic ethanol production technology was performed based on of the cellulosic ethanol production project investment scheme parameters and the minimum ethanol selling price (MESP) was obtained when the net present value of cellulosic ethanol production process equal to zero. Besides that the sensitivity analysis of raw material price was performed. The calculation predicts that the total investment costs of these three kinds of technology projects are RMB ￥2.847 billion, RMB ￥2.856 billion and RMB￥2.902 billion, respectively; the operating costs in the process of ethanol production are RMB ￥2.59/L, RMB ￥2.74/L and RMBY2.64/L; and the minimum ethanol selling price are RMB ￥4.32/L, RMB ￥4.62/L and RMB ￥4.59/L, when the cellulosic ethanol production process reach the break even limit in the life cycle. Obviously, the dilute acid process is the best, and the ammonia fiber explosion process is the worst, but the disparity of these three cellulosic ethanol production process is narrow. The raw material price accounts for the largest in MESP of three processes, so the sensitivity analysis of corn stover price was performed. And sensitivity analysis shows that the change of corn stover price has the lowest effect on dilute acid process, and the effects on the other processes are not too dissimilar.