Energy Analysis And Optimization Of Syngas Directly Synthesis Dimethyl Ether In Slurry-bed Reactor

With the large-scale and irrational use of fossil resources, it causes greatdamage to the human survival environment and emits a large number ofpollutants and greenhouse gas. Coal-based synthetic fuels have become the newtheme in the field of energy. The syngas directly synthesis dim ethyl ether inslurry-bed reactor system has the characteristics of short process, lessinvestment in equipment, low energy consumption and one-way conversion rateof Carbon monoxide is high. It has become the focus of development directionin coal chemical industry.In this paper, the system utilizes the aspen plus software to simulate thesystem process. On the base of a large amount of literature data must becollected to adjust the aspen plus software. Researched for the dimethyl ethersynthesis system, the dimethyl ether-electricity co-generation system, thedimethyl ether distillation system. Analysis of the influence betweencirculations ratio and energy consumption of this system. The results show thatthe optimum circulation ratio is1.5. Also analysis of each process of distillation,the results show that the separation sequence, which water is first separated,then the methanol is separated, carbon dioxide and dimethyl ether are separated finally, is the minimum loss of energy and exergy in distillation system.On the basis of the analysis, energy method and exergy method are used toanalyze the system. The energy flow chart and the exergy flow chart areproduced for this system. The energy method results show that dimethyl etherconversion efficiency was47.16%, methanol conversion efficiency was6.37%,and power conversion efficiency was3.47%. After the transfer, the energy lossof steam and cooling water were20.21%. The energy loss of invalid products(carbon dioxide separated from distillation unit and the flue gas from Waste heatboiler unit) was7.42%. The sum energy loss in every process was15.66%, theenergy loss of heat exchange in the process of reaction, distillation process andpower generation in the Waste hear boiler process were bigger. The exergymethod results show that dimethyl ether conversion efficiency was39.03%,methanol conversion efficiency was5.29%, and power conversion efficiencywas2.64%. After the transfer, the exergy loss of steam and cooling water were4.38%. The exergy loss of invalid products was3.71%. The sum heat exchangeexergy loss in every process was20.18%, the exergy loss in equipment was3.01%, the exergy loss in mixing and shunting were0.38%, the exergy loss ofthe process of power generation unit was3.87%, and the exergy loss of theprocess of dimethyl ether distillation was17.51%. It needs higher quality energyfor distillation process and heat exchange in the process of reaction, so the lossof exergy is bigger. If reasonable distribution of energy, it is not only reducesthe input of high quality energy, but also increases the energy utilization, reducing the loss of exergy and improving the efficiency of exergy.According to the energy method and the exergy method, the results that thebigger loss of energy and exergy were dimethyl ether distillation process andheat exchange in system. The heat integration can make sure the use of energyand exergy rational and improve the efficiency. Carbon dioxide separated fromdistillation unit and the flue gases from Waste heat boiler unit were also bigger,but the power capability was low and the economic effect was not obvious.