CFB-FGD布袋除尘器内气固流动特性的数值模拟研究

采用k-ε双方程湍流模型和离散相模型对循环流化床烟气脱硫(CFB-FGD)布袋除尘器内气固两相流动进行了数值模拟,分析了进口烟道结构形式、气流均布板和锅炉负荷等对改进前后布袋除尘器的流场分布、阻力特性及颗粒相流动状况的影响规律.模拟结果表明,渐扩型进口烟道和具有一定开孔率的气流均布板可很好地改善除尘器内流场分布的均匀性.与布袋除尘器原型相比,改进型除尘器内的颗粒流动更加均匀,同时灰斗积灰对颗粒相均匀分散有一定的改善作用.不考虑粉尘堆积情况下,改进型布袋除尘器总阻力损失与锅炉负荷满足二次函数关系.

Numerical Simulation on Gas-solid Flow Characteristics of a CFB-FGD Bag-Filter

Based on the k-ε two-equation turbulence model and discrete phase model（ DPM ） ,the numerical simulation of the gas-solid two-phase flow characteristics of original and modified bag-filters for circulating fluidized bed flue gas desul- phurization（CFB-FGD） is carried out. The effects of flue gas duct structure,flue gas distributor and boiler load on flow filed distribution, resistance properties, particle flow trajectory of original and modified bag-filters are analyzed. Simulation results indicate that the uniformity of flow field distribution in the bag-filter can be improved by diverging inlet flue gas duct and flue gas distributor with a certain opening ratio. The particle flow in modified bag-filter is more uniform than that in original bag-filter, and fly ash deposition in the hopper can enhance the particle distribution in the modified bag-filter. The resistance loss of modified bag-filter and the boiler load meet the needs of quadratic function under no ash deposition in the surface of filter bag.