错流移动颗粒床高温除尘模拟和操作特征分析

Modeling and Operating Characteristic Analysis of the Moving Granular Bed for Hot Gas Cleanup

颗粒层内的沉积粉尘是影响颗粒床过滤器除尘效率和操作压降变化的重要因素,考虑颗粒层内沉积粉尘对除尘过程的影响,基于捕集单元的收缩管模型,建立了二维的气固错流移动颗粒床过滤器除尘过程的数学模型。分析了主要设计和操作参数对颗粒层除尘效果的影响,并对颗粒层内气体流动规律、粉尘沉积特点和气体含尘浓度变化进行了模拟分析。颗粒层内的沉积粉尘在气、固流动方向上具有二维分布的特点,沉积粉尘分布导致局部气体过床的阻力和捕集单元除尘效率的变化。模型计算结果和高温煤气除尘实验数据比较表明,表观过滤气速0．1～0.3 m/s范围内,计算值与实验结果吻合较好,可适用于过程的设计和优化。

The dust deposit has a significant effect on the collection efficiency and the pressure drop of the granular bed filter. Considering the effect of the deposit, the hydrodynamics of gas flow and the collection of particulates, a comprehensive mathematical model based on the constricted-tube concept of collector element was established to simulate the dust removal performance and operating characteristics of the cross-flow moving granular bed filter. The effect of the length of the granular bed, the granular moving speed and the distribution characteristics of the dust deposit, the gas velocity and the dust concentration were analyzed theoretically. The results shows that the dust deposit identifies with the 2-D distribution along the gas flow and the solid moving directions. The dust deposit may influence the gas flow resistance and the collection efficiency. There are less dust deposit, higher gas flow rate and lower dust removal efficiency at the upside of the granular bed. The distribution may be promoted with the increase of the height of the granular bed and the decrease of the solid moving speed. The corresponding experimental investigation was also conducted in a bench scale equipment. The model test showed that the model calculating values including the pressure drop and the collection efficiency were in good agreement with the experimental data for the superficial gas velocity from 0.1 to 0.3m/s. It can be used for the process design and the optimizing operation parameters.