| "Energy and resources" is the eternal theme of mankind.Shale oil can be used as supplementary energy for petroleum by retorting of oil shale.At present,Fushun type gas heat carrier retorting furnace is mainly used in China to obtain shale oil,which has low oil yield,serious waste of oil shale,environmental pollution and relatively backward technology.Therefore,grasping the mechanism of oil shale retorting refining and developing advanced oil shale gas heat carrier retorting furnace are the key problems of basic application that need to be solved,and also the way to control pollutants and efficient energy saving in the comprehensive utilization of oil shale.Taking Wangqing oil shale as the research object,this paper adopts the method of combining experimental research and theoretical research to closely focus on the gas release characteristics and pyrolysis reactivity in the pyrolysis process of Wangqing oil shale.The FLASHCHAIN model is used to predict the generation rules of pyrolysis gas products.The heat source of oil shale gas heat carrier retorting--the generation law of pyrolysis gas products was thoroughly explored.The three-dimensional numerical simulation of the retorting process in gas heat carrier retorting furnace was carried out,and a new type of gas heat carrier retorting device was developed.In this paper,the mechanism of oil shale pyrolysis gas release was studied from macro to micro,from apparent to intrinsic,and from experimental research to simulation calculation and design and development,the advanced oil shale gas heat carrier retorting system was finally developed and verified by engineering experiments.The main work of this paper is as follows:The distribution of functional groups and carbon skeleton structure of organic structure of Wangqing oil shale was analyzed by 13C-NMR and FT-IR,and the pyrolysis kinetics of Wangqing oil shale was calculated by combining TG-FTIR results.The release characteristics of pyrolysis gas during the pyrolysis of Wangqing oil shale were investigated by peak-splitting fitting method.TG analysis results were used to study the pyrolysis characteristics of Wangqing oil shale at different heating rates.Kinetic parameters of low temperature pyrolysis of oil shale were calculated by Friedman method,FWO method and DAEM model.The results show that the-COOH functional group will decompose to generate CO when the temperature is above 200?.When the pyrolysis temperature exceeds 600?,carbonate continues to generate CO gas,accompanied by a small amount of CO precipitation.The apparent activation energy calculated by FWO method and Friedman method varies continuously with the conversion rate for the pyrolysis of clear oil shale.The average activation energies of the two methods were 233.71 kJ/mol and 234.61 kJ/mol,respectively.Combined with F test and quantity criterion test,the Logistic DAEM model is suitable for solving the kinetic parameters of the oil shale,and the activation energy of low temperature pyrolysis is 238.67 kJ/mol.The release law of light gas during pyrolysis of Wangqing kerogen was investigated.The FLASHCHAIN model and density functional theory were used to predict the formation characteristics and reaction mechanism of pyrolysis products,and the change rules of main functional groups of kerogen at different pyrolysis temperatures were studied to determine the main sources of gases precipitated during pyrolysis.The results show that the pyrolysis gas products of kerogen are mainly hydrocarbon with low carbon number,and a small part is CO2 and CO.With the process of pyrolysis,the vibration intensity of aliphatic hydrocarbon region in kerogen FT-IR gradually decreases and finally disappears.During the pyrolysis of kerogen.the formation of CO is characterized by lipid structure,carbonyl structure and ether bond structure.Whether they are aliphatic or aromatic,they form CH4 mainly occurs in the process of H atom transfer,and heteroatom O contributes to the pyrolysis of the parent material of shale oil to form CH4.The branching degree of alkane chain of kerogen decreases first and then increases,and then decreases again.The branching degree of alkane chain of kerogen is-CH2-at 470?and-CH3.The ratio of vibration absorption peak area to the maximum is 7.064.The three-dimensional numerical simulation of gas heat carrier distillation process was carried out by using ANSYS-FLUENT.The porous medium model was used in the FLUENT,and the flow and heat and mass transfer process in the furnace were simulated by using a custom program.The results show that the porous media model based on Ergun equation and the RNG K-? midstream turbulence model can better match the heat and mass transfer process in the process of retorting.the research results can provide a theoretical basis for the design and development of gas heat carrier retorting furnace.In order to ensure the effect of retorting and improve the contact area and time between gas and particles,coaxial or eccentric axial impinging flow distribution can be formed in the retorting section.The heat and mass transfer model of oil shale particles is established to predict the variation of temperature,moisture and volatiles in the bed with time.When the inlet gas velocity and temperature are increased 1.5 m/s and 100?.the pyrolysis process of kerogen is accelerated by 1600s and 600s,respectively.When the inlet velocity and temperature are reduced 1.5 m/s and 100?.the kerogen pyrolysis process is reduced by 1600s and 600s,respectively.In addition.when the intake temperature is increased or decreased by 100?,the maximum evaporation rate of water in the early pyrolysis process is increased by 11.4%or decreased by 24.7%.respectively.According to the analysis of organic structure and pyrolysis gas release characteristics of Wangqing oil shale and kerogen.a new gas heat carrier distillation system was developed on the basis of numerical simulation of the distillation process.and a pilot-scale experiment was carried out.The results show that the design of heating capacity of the distillate conforms to the process requirements.The average heating temperature of hot gas is 572? in actual operation,and the maximum temperature of constant temperature section in the distillate is 520? to 550?.The difference between the average gas temperature and the maximum distillation temperature in the distillate furnace is 30? to 50?.The distillate furnace has better insulation effect.The new gas heat carrier retorting device realizes the dry discharge of coke,and the water content of half coke is less than 2%,which can be directly used as the fuel of circulating fluidized bed boiler,and the gas heating furnace has no problem of carbon accumulation and coking.During the experiment,the oil recovery rate was 91.7%,which laid a foundation for the engineering and large-scale development of the new gas heat carrier distillation furnace. |
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