Simulation And Energy Integration Analysis In Coal And Biomass To Oil Process

With the increasing scarcity of oil resources, coal and biomass as raw material through the Fischer-Tropsch (FT) synthesis to generate liquid fuel is one of the most important methods to solve the oil shortage. Compared with oil, coal reserves are more abundant, and biomass is a kind of environment-friendly resource. Therefore, the research on coal and biomass to oil is of strategic significance.Software ASPEN PLUS was used to simulate coal and biomass to oil(CTL and BTL) process, which included five parts, there were gasification, water gas shift, syngas synthesis, FT reaction and combined cycle power generation. There were two main differences between CTL and BTL. Firstly, coal was gasified directly, however, biomass needed to be pyrolysised to bio-oil which gasified for syngas. Due to complexity of bio-oil composition, acetic acid, acetol, guaiacol and water were selected to substitute bio-oil in ASPEN PLUS simulation. Secondly, rectisol was selected as the syngas purification method in CTL process because of high sulfur content, and selexol was used in BTL process. The results show that CTL process has larger economic benefit and more CO2emission when the coal and bio-oil treated with the same inputs. Through the technology is more mature in CTL, and some bottlenecks need to be solved in BTL, however, BTL will become the future trend of development considering the perspective of sustainable development.Tail gas which contained light hydrocarbons and unreacted H2and CO, was cogenerated with liquid products in FT synthesis unit. The tail gas could provide utility through combustion system. The supply and demand of utility was influenced by the different treatment methods of tail gas. Take CTL process for example, there were four tail gas treatments selected, which included full combustion, H2and CO full recovery by membrane and pressure swing adsorption(PSA) respectively, partial combustion and recovery by auto thermal reform(ATR). The results show that the process utility can achieve self-sufficiency only in the full combustion case. The ATR case has the largest economic benefit, and it is increased by31.7%compared with full combustion case. However the ATR case leads to more CO2emission which is increased by20.2%.Besides liquid oil products, methanol and power can be directly generated with coal as raw material, and chemical products and power were cogenerated in CTL, BTL and CTM when considering the combined heat and power integration. It was called chemical products-power cogeneration in this paper. The economic benefit, CO2emission and the technology were analyzed between chemical products-power cogeneration systems and IGCC which generated power only. The results show that chemical products-power cogeneration process has larger benefit, and CTM has the largest benefit compared with IGCC system. Although the technology of CTM is maturer, BTL-power will be the future direction of development.