Numerical Simulation Of Drying Oil Shale And Drying Kinetic Analysis

Energy has been recognized as the basis of modern human civilization and social development, the rapid development of economy leads to the huge energy consumption and fossil fuel reserves are dwindling, so many countries in the world begin to find alternative sources. Owing its rich world reserves, oil shale is a good alternative sources of energy. But oil shale mined has high moisture content, the high moisture content are adverse to oil shale distillation and oil shale combustion for power generation. Oil shale fluidized bed with high drying efficiency, but the internal heat and mass transfer model lack reliable simulation parameters. Therefore, drying process of single oil shale particle was simulated in this paper, and the analysis of different drying media traditional hot air and superheated steam on drying oil shale process, some related parameters calculation are formulated. The mass transfer process of fluidized bed dryer is complex, and the semi empirical model based on the theory of drying dynamics is used to predict the change of wet mass.A drying oil shale mathematical model on hot air drying process is established based on the Whitaker theory solved by the finite element numerical calculation software COMSOL, it reveals the variation of internal temperature and moisture content of oil shale on hot air drying process, the main driving force of drying process found at the boundary of is concentration gradient of the water vapor; The relative moisture content have a significant influence on the simulation; higher hot air temperature leads to the faster drying rate; During the drying process, internal temperature, humidity and pressure of particle display the anisotropy characteristics affected by oil shale flake structure; The calculation formula of effective water diffusion coefficient of hot air drying of oil shale is built. A double field model coupling temperature field and humidity field based on the gradient driven model is established for simulating superheated steam drying single oil shale particle process, COMSOL software is used to solve the coupled equations, and drying moisture effective diffusion coefficient were discussed in detail, draw the calculation expression of the particle size, moisture and temperature; Superheated steam drying oil shale owns higher moisture diffusion coefficient by comparing the hot air drying process.Based on the drying kinetics theory of hot air flow drying oil shale, the drying kinetics analysis for oil shale is conducted, comparing different thin layer drying theory fitting results, select the most appropriate model used to predict the drying process, and provide theoretical guidance for fluidization drying oil shale; on drying rate constants of the influence factor analysis, its type of correlation and the effective diffusion coefficient, effective diffusion coefficient model combined with single grain drying process, derived calculation expression of the drying rate constant.The numerical study of single particle shale oil drying and fluidized bed heat transfer, and oil shale drying kinetics analysis will be benefit for the dry oil shale industry to make a further study on the mechanism and better equipment design.