Numerical Simulation Research On Flow And Combustion In Oil Shale Circulating Fluidized Bed

Oil shale is a kind of important potential energy, which has high volatile and low calorific value. Among the fossil fuels, its reserve in terms of the calorific value is only next to coal. It is the important replacement of oil and natural gas. The by-product of oil shale retort processing is called semi-coke, and semi-coke is very difficult to ignite and burn out. Therefore, we can mix oil shale with semi-coke, and send them in the CFB boiler, achieving the goal using of oil shale resources.In this thesis, in order to understand the combustion characteristics of oil shale and semi-coke, a CFB test rig was designed and set up at the Northeast Dianli University. The simulation experiments were done by using FLUENT and the models took into account CFB hydrodynamic model, heat transfer model and combustion model. The flow characteristics and combustion characteristics were simulated and discussed, which provided theoretical basis for oil shale CFB large-scale design EULERIAN two-fluid model was applied to simulate the flow characteristics.The effect of different drag model was analyzed and the distribution rules of particle velocity and concentration by changing wind speed and particle sizes were obtained, which was consistent with the core-annulus flow style. Comparing simulated results and experimental data, it proved that the simulation result is reasonable.Non-Premixed Combustion model was applied to simulate the combustion characteristics. The effect of different turbulence model was analyzed and the temperature distribution, component distribution and burn out level were obtained at different conditions. The simulation study on combustion performance of semi-coke and their mixture of shale and semi-coke was conducted. Then the best mixing ratio was got to achieve the objective of maximizing the use of oil shale.