Study On Chemical Reaction Mechanism Of Coal-derived Naphtha Based On JSR

To cope with the increasing energy crisis and air pollution,clean alternative fuel and new combustion technology of internal combustion engine have been paid much attention.Based on the characteristics of my country's coal-rich,oil-deficient,and low-gas resources and the current situation of increasing dependence on foreign oil,the development of coal-to-liquid technology is a key decision to alleviate my country's energy imbalance.Coal-derived naphtha is an important way for clean utilization of coal,with mature preparation technology and rapid increase of production capacity.It contains almost no aromatics,has high low calorific value,good evaporation and mixing property,and is an ideal fuel for internal combustion engines.At present,domestic and foreign scholars have little research on the basic combustion of coalderived naphtha,and there is a lack of establishment of a kinetic model for the low-temperature combustion of coal-derived naphtha.Therefore,it is necessary to conduct an in-depth study on the chemical reaction kinetic mechanism of coal-derived naphtha.According to the physical parameters of coal-derived naphtha and the three principles of selecting the characterizing fuel,the characterizing fuel groups were determined as n-heptane,iso-octane and methylcyclohexane.Based on the CHEMKIN software,an intelligent characterization fuel mixture optimizer was proposed,using a built-in genetic algorithm optimization method.After accurate calculation,the characterization fuels of coal-derived naphtha were 43.8% n-heptane,44.2% iso-octane and 12.0% methyl cyclohexane by volume.In this paper,the medium-low temperature oxidation test rig was established with JSR and GC-MS as the main components.Under different equivalence ratios(?=0.3,0.5,1.0 and 2.0),temperature 700K~1200K and atmospheric pressure 1atm,a comprehensive study of the oxidation process of coal-derived naphtha and characterizing fuels was carried out.Through the chromatogram and mass spectrum generated by the GC-MS,the qualitative and quantitative analysis of the change law of the mole fraction of the main substances with temperature during the oxidation process.A total of 16 substances were measured in the experiment,and it was found that the experimental values of the two substances were well fitted,which proved that the characterization fuels selected in this paper were correct.Based on software CHEMKIN of n-heptane,isooctane,methyl cyclohexane was analyzed,and the main reaction path,on this basis,a Primary Reference Fuel(PRF)-methylcyclohexane(MCH)mechanism is constructed,which contains 1563 components and 6719 reactions.The mechanism of PRF-MCH was simulated using the PSR model in CHEMKIN software,and the simulated data were compared with the experimental values of coal-derived naphtha and characterized fuel.The oxidation rate of the fuel gradually decreases with the increase of equivalence ratio,while the temperature at the beginning and the end of the reaction increase.The simulation data and experimental values are in good agreement,indicating that the PRFMCH mechanism constructed in this paper can predict the experimental results well.