Study On Kinetics Model And Simulation Process Of Direct Coal Liquefaction Of Shenhua Coal

In China, coal is the most abundant fossil fuel, but oil and gas resources are relatively poor. Today, coal combustion, at a lower energy efficiency, is the main consumption way which leads to many serious environmental pollution. Direct coal liquefaction (DCL) as one of the clean coal technologies, has attracted a continuous interest for producing the substitutable transportation fuels, especially in China. Direct coal liquefaction, a complex combination of physical and chemical process, refers to the direct reaction of coal with high pressure hydrogen to form liquids in a solvent under high temperature. The studies on the mechanism and kinetics of direct coal liquefaction are beneficial to reactor design and process optimization.In this paper, the kinetic model was established based on 0.01t/d Direct Liquefaction of Shenhua Coal continuous facility of Shanghai Research Institute of China Shenhua coal to liquid and chemical Co., Ltd. By using BFGS optimization algorithm, kinetic parameters of the model were obtained on the premise that the early and later reaction periods are a continuous whole. The results showed that the average relative and absolute errors between model calculated values and experimental values of the early reaction period were 2.74% and 1.84% respectively, and ones of the later reaction period were 6.61% and 1.20% respectively, so the simulated results were good agreement with the experimental ones. And the kinetic model can describe and reflect the reaction process of direct liquefaction of shenhua coal. In order to further predict distributions of different gas molecules in the gas lumped and narrow distillates in the oil lumped, the correlation models were developed with the reaction conditions, and the results were good.Meanwhile, this study used Aspen Plus, the chemical process simulation software, to complete the process simulations of coal slurry preparation unit, liquefaction reaction unit and separation process. Aspen Plus’s built-in unit models are unable to simulate the complex reaction process of coal direct liquefaction, so Aspen Plus user models of preheater and reactor in direct liquefaction of Shenhua coal were developed with Fortran language. And the interface program was written to achieve the coal slurry preparation unit and liquefaction reaction unit simulation of direct coal liquefaction process, which connects the user models with built-in unit operation models in Aspen Plus software. In addition, a virtual component model of the coal liquefied oil fractions was set up with Aspen Plus software. And the COAL-LIQ property method was used to estimate the critical properties of the fractions. Then we built the flash process simulation. Through comparison between the simulation data and the real data, suitable property method was selected for the high pressure system of coal liquefaction, and the simulation results with GRAYSON method and UNIFDMD-RKS method fitted the experimental value of high and low temperature separators respectively.