Knowledge Management System Of Institute of process engineering,CAS
|Process Integration and Analysis of Liquid Fuels and Hydrogen Production by Oil Shale|
|MUHAMMAD AFZAL RAJA|
油页岩是世界上储量丰富的非常规化石燃料之一，油页岩的高质化利用成为当今能源领域的研究热点。本研究的创新点是模拟了同时包括干馏、加氢、费托合成三种技术的油页岩联产氢气和商用液体燃料的工艺。为了深入理解油页岩的加工过程，充分发挥联合工艺优势，提高实际装置效率，开展对油页岩提质的过程模拟、集成和分析研究意义重大。本论文主要针对油页岩联产氢气和液体燃料系统进行研究，对油页岩干馏、干馏气重整、页岩油加氢等关键单元进行模拟及集成，通过物流分析、能流分析、灵敏度分析和产品分布分析，提出油页岩综合利用的优化路线。主要研究内容和结论如下:（1）采用ASPEN软件对油页岩干馏过程进行了系统模拟和分析。首先采用物性方法估算得到油页岩非常规组分基本物性，基于过程分析，建立干馏反应动力学，采用RCSTR模型对干馏过程流化床反应器进行模拟计算，通过参数优化得到510℃条件下，液体收率最佳、能耗最低。其次，采用RGIBBS方法模拟了干馏残渣的的燃烧过程，通过调节操作变量获得燃烧过程的影响规律，在此基础上，对油页岩预处理-干馏-干馏残渣燃烧-油气分离单元的全过程进行系统集成，开展了干馏全过程的物流分析-灵敏度分析-能流分析。模拟结果表明，在最优工艺条件下（510℃，1 bar，74wt%废页岩回收率，33wt%干馏气回收率），可以得到31.6wt%的干馏气和68.4wt%的页岩油。（2）对干馏气净化及制氢单元进行了模拟分析。采用含ZnO的固定床工艺实现干馏气中硫的有效脱除，硫的脱除率高达99.5%。采用平衡反应模型对甲烷重整制氢过程进行了模拟分析，获得了温度，压力，蒸汽/碳比对重整制氢过程的影响规律，优化的制氢最佳条件为: 压力22bar，温度950℃，蒸汽/碳比为4。在此基础上，对干馏气净化-蒸汽重整-水汽变化-变压吸附单元进行全过程模拟，及物流和能流的评价分析。模拟结果表明，90%以上的氢均可被回收利用，氢气产品和页岩油的系统能效分别为4.40%和49.59（HHV%）。（3）模拟分析了页岩油的加氢提质过程。建立了页岩油各组分的加氢反应网络及反应动力学，开发了沸腾床和两段固定床的反应器模型，获得了各操作变量对加氢过程的影响规律，优化了反应条件。对加氢提质过程进行了物流-能流的模拟分析，计算得到高附加值的燃料收率分别为：中间馏分（68.97wt%），(柴油>80 %)，石脑油（9.98wt %），低硫燃料油（19.21wt %）。各产品的系统能耗占比分别为：中间馏分54.54（HHV%），石脑油7.10（HHV%），低硫燃料油16.47（HHV%）。（4）对油页岩生产氢气和液体燃料的两种工艺进行了模拟，并对其产品组成和能量效率进行了对比分析。方案一为干馏后的页岩油经过加氢工艺得到液体燃料；干馏气经过蒸汽重整得到氢气。方案二主要包含干馏、干馏气蒸汽重整、页岩油加氢和费托合成。对两种方案进行了综合评价，进行了物流分析、能流分析和灵敏度分析。模拟结果表明，方案二的烃类油产率比方案一高0.95wt %，但氢气产量要高14.7 %。方案二中的外界能耗比方案一要高20 %；方案一的系统能效为43.45（HHV %）, 方案二的系统能效为43.16（HHV %）。;Oil shale is one of the largest, relatively undeveloped unconventional fossil fuel resources in the world. The clean processing and utilization of oil shale has become the research hotspot in today’s energy field. The novelty of the present work is the modeling and simulation of oil shale to liquid fuels, syngas to liquid fuels and retorting gas steam reforming processes for the simultaneous production of hydrogen and commercial spec fuels. To insight understand the whole system and to provide representative routes for efficient larger scale oil shale technology utilization, a systematic study on the process simulation of oil shale upgrading is of great significance. Based on the background above, a comprehensive assessment based on energy flow, mass flow, sensitivity and product distribution analysis of the whole oil shale utilization system were conducted in this thesis, furthermore, key units in this system like oil shale retorting, retorting gas steam reforming, shale oil hydrogenation and Fischer-Tropsch (F-T) were simulated and analyzed. The main content and results in this thesis are listed below:The process of oil shale retorting is systematically simulated and analyzed. Firstly, the basic physical properties of oil shale unconventional components are obtained by physical property method. Based on the process analysis, a kinetic reaction model of the oil shale retorting is established. The RCSTR model is used to simulate the fluidized bed reactor in the retorting process. The optimum yield and the lowest energy consumption are obtained under the condition of 510 ℃. Secondly, the RGIBBS method is used to simulate the combustion process of spent shale, a comprehensive assessment of combustion process is obtained by adjusting the manipulated variables. On the basis of this, the whole process of oil shale pretreatment – oil shale retorting – spent shale combustion - oil and gas separation unit is systematically integrated, and the process of energy analysis - sensitivity analysis - energy flow analysis is carried out. The simulation results show that the hydrocarbon products produced under the optimum operating conditions (Temperature 510 ℃, Pressure 1 bar, mass ratio of recycled spent shale 0.74, mass ratio of recycled retorting gas 0.33) are as, retorting gas accounts for 31.6 wt % and shale oil accounts for 68.4 wt %.The oil shale retorting gas cleaning and hydrogen production units are simulated. Firstly the fixed bed ZnO technology is used to achieve effective removal of sulfur from the retorting gas, sulfur removal rate as high as 99.5 %. Then the equilibrium reaction model is used to simulate the hydrogen production process of retorting gas steam reforming. Secondly, the sensitivity analysis of temperature, pressure and steam / carbon ratio on the hydrogen production process is carried out and the optimum conditions are as follows, pressure 22 bar, temperature of 950 ℃ and a steam / carbon ratio of 4. Thirdly, the process simulation of the whole process of the oil shale retorting gas cleaning - steam reforming - water gas shift - pressure swing adsorption unit is carried out, and the mass and energy flows were analyzed. The simulation results indicate that the total energy contained in products as result of the oil shale retorting gas steam reforming and hydrogen production system is as; hydrogen contains 4.40 % (HHV) and shale oil contains 95.59 % (HHV) and the overall energy efficiency of the system is 49.59 % (HHV).The shale oil upgrading process is simulated and analyzed. The hydrogenation reaction network and reaction kinetics of each component are established. On this basis, the reactor models of ebullated bed and two fixed beds are developed. The influence of each manipulating variable on the hydrogenation process is investigated, and the reaction conditions are optimized. At the same time, the mass and energy flow analysis of the hydrogenation process are carried out. The simulation results show that fuel yield with high added value as: middle distillate (68.97 wt %) (the middle distillate contains diesel oil > 80 %), naphtha 9.98 wt %, low sulfur fuel oil (19.21 wt %). The energy contained in the products is as: middle distillate 54.54 (HHV %), naphtha 7.10 (HHV %), low sulfur fuel oil 16.47 (HHV %).(4) The two processes of producing hydrogen and liquid fuels for oil shale are proposed and simulated, and their product distributions and energy efficiencies are compared and analyzed. In the case 1, the shale oil after the oil shale retorting is subjected to a hydrogenation process to obtain liquid fuels and the retorting gas is steam reformed to obtain hydrogen. In case 2, the main processes include oil shale retorting, retorting gas steam reforming, shale oil hydrogenation and Fischer-Tropsch synthesis. In this study, the two cases are evaluated systematically, and the mass flow analysis, energy flow analysis and sensitivity analysis are carried out. The simulation results show that in case 2 the overall production of hydrocarbon fuels increases 0.95 wt % than in case 1 but the production of hydrogen reduces 14.7 % in case 2 than in case 1. The external energy consumption in case 2 is 20 % higher than that of case 1. The results also show that the energy efficiency of the case 1 is 43.45 (HHV %), and the energy efficiency of the case 2 is 43.16 (HHV %).
|MUHAMMAD AFZAL RAJA. Process Integration and Analysis of Liquid Fuels and Hydrogen Production by Oil Shale[D]. 中国科学院大学,2017.|
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