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为了更好地研究流化床内复杂的运动和颗粒间的混合情况,为流化床的设计及优化提供参考,采用欧拉–拉格朗日坐标系下的离散单元法软球模型在二维空间对单孔射流流化床内气固两相流动进行了数值模拟。其中颗粒相采用离散单元法,气相的计算采用SIMPLER算法,气固两相间遵循牛顿第三定律建立耦合模型,并用FORTRAN语言编程计算来实现。在假设不考虑传热、燃烧及颗粒转动的条件下,模拟得到了流化床内上下两层颗粒的运动和混合情况、气固两项的速度分布以及颗粒的浓度分布。模拟结果表明:由于受到空气射流的影响,流化床内存在强烈的颗粒返混和内循环现象。固体颗粒在横向和纵向都存在一定的浓度梯度,在空间中的碰撞次数分布也有不同,颗粒浓度高的地方颗粒碰撞和混合会更剧烈。
In order to better study the complicated motion and interparticle mixing in the fluidized bed and to provide references for the design and optimization of the fluidized bed, the discrete element softball model under Eulerian- Dimensional space Numerical simulation of gas-solid two-phase flow in a single-hole jet fluidized bed. Among them, the discrete phase method is adopted for the grain phase, the SIMPLER method is used for the calculation of the gas phase, and the coupled model is established according to the third law of Newton between the gas and solid phases, and is realized by programming with FORTRAN language. Under the assumption of not considering the heat transfer, combustion and particle rotation, the motion and mixing of upper and lower particles in the fluidized bed, the velocity distribution of gas and solid and the particle concentration distribution were simulated. Simulation results show that due to the influence of air jets, there is a strong particle backmixing and internal circulation in the fluidized bed. Solid particles in both horizontal and vertical concentration gradient exists in the spatial distribution of the number of collisions are also different particles in high concentrations where particles collide and mix more severe.