Simulation,Development And Optimization Of The Oil Shale Refinery Process

Oil shale,a kind of unconventional fossil fuels,is abundant in reserves.Its exploration and exploitation are significant to the development of alternative oil-gas strategic emerging industries,and the reduction of dependence of imported oil in China.Compared with the petrochemical industry,however,oil shale industry is still relatively backward and has many shortcomings,such as low oil yield,poor quality of oil,inefficient utilization of retorting gas,unsatisfactory economic performance,and serious environmental pollution.To date,nevertheless,little work has been published on process integration of the oil shale refinery technology,high value-added utilization of oil-gas products,reduction of pollution,or cascade utilization of energy.These problems severely restrict the large-scale utilization and sustainable development of oil shale resources.Therefore,this thesis builds the models of key units and the whole system of the oil shale refinery process.These models are validated by comparison with the industrial data.On the basis of the reliable models,the material,energy utilization,and bottleneck of the oil shale refinery process are identified by conventional and advanced exergy analysis.Results show that the exergy efficiency of the oil shale refinery process is 34.17%.The key parameters of the retort are optimized since it has the largest improvement potential.As a result,the avoidable exergy destruction of the retort is reduced by 28%.To address the deficiencies of conventional thermodynamic and economic analyses,a framework based on advanced exergoeconomic analysis is proposed for system evaluation and optimization.A conventional oil shale refinery process is used to illustrate the application of the proposed framework and demonstrated its advantages on quantify of the avoid cost/exergy destruction,analysis of the relationship of different units,and determination of the real improvement potential of the system.Results show that the real improvement potential of the oil shale refinery process is 35.75%.Therefore,efforts to optimize the performance of the process should be focused on reducing the exergy destruction costs.Following the system optimization,with the goal of minimizing of total avoidable costs and total production costs,the cost per exergy unit of product of the six units of the oil shale refinery process are decreased by 6.93-11.28%.The total avoidable cost is reduced by 17.03%.Facing with the problem of inefficient utilization of retorting gas and poor quality of oil,this thesis proposes a novel oil shale refinery process integrated with retorting gas and shale oil upgradation(OSR-HPHD)process.The process is more ingenious to convert the effective components of retorting gas into high purity and high economic valued hydrogen product.Part of the produced hydrogen is used to shale oil hydrogenation unit to reduce the production cost and further improve the economic benefit of the whole process.Referring to the results of the whole process simulation and parameters optimization,the techno-economic performance of the novel process is analyzed.Compared with a conventional Fushun-type oil shale refinery(FSOSR)process,a FSOSR process integrated with hydrogen production from retorting gas(OSR-HP),and a FSOSR process integrated with hydrogenation of shale oil(OSR-HD),results show that the OSR-HPHD and the OSR-HP processes have the best economic performance.Especially they can turn losses of the FSOSR and the OSR-HD processes into profits at the situation of low oil price.The OSR-HPHD process is suggested to the oil shale plants which use the oil shale with high oil content;on the contrary,they are better to select the OSR-HP process.To efficient utilization of fine oil shale,associated coal and semi-coke,the thesis proposes an oil shale retorting process integrated gas and solid heat carrier technologies(OSRGS),an oil shale refinery integrated with coal gasification for hydrogen production(OSR-CGH),and an oil shale comprehensive utilization process integrated with semi-coke for electricity generation(OSR-SCE).A detailed techno-economic analysis of these proposed process are conducted.Compared with the FSOSR process,the OSRGS process not only increases the resource and energy utilization ratios,but also makes the internal rate of return of the FSOSR process increased by 6.55% since it can produce more shale oil and electricity.The internal rate of return of the OSR-CGH process is increased by 7.39% because it produces lots of high economic valued hydrogen and fuels products.The OSR-SCE process uses the semi-coke for power generation and the ash for building materials production.It makes waste profitable and obviously increases the economic performance of the FSOSR process.Therefore,these novel processes proposed in this thesis can effectively improve the technical-economic-environmental performance of the FSOSR process,and provides a substantial theoretical and technical foundation for the future large scale development of oil shale resources.