1000 MW机组静电除尘器对粉尘颗粒脱除的数值研究

Numerical Investigation on Removal of Dust Particles by 1000 MW Electrostatic Precipitator

基于计算流体动力学软件FLUENT,对某电厂1 000 MW机组的电除尘器(ESP)流场、电晕电场和颗粒运动场进行三维数值模拟,其中流场的模拟采用k-ε双方程,电晕电场采用有限体积法,颗粒相运动采用拉格朗日方法,数值计算采用SIMPLE算法,在验证该数值模拟结果合理的前提下,模拟了出口压力、烟气流速、粉尘浓度及粉尘粒径对电除尘器除尘效率的影响。结果表明:粉尘脱除效率随出口压力绝对值的减小而增大,且当出口压力维持在-3 000 Pa^3 500 Pa时,电除尘器运行稳定;在较高的烟气流速下飞灰颗粒所受惯性力增大,克服电场力逃逸收尘板捕获的能力增强,使得电除尘器收尘效率降低;当烟气粉尘浓度维持在30 g/m^3时,电除尘效率最高;粉尘粒径越大,电除尘器收尘效率越高,但增长速率减缓。

Based on computational fluid dynamics software Fluent,a three-dimensional numerical simulation was performed for the electrostatic precipitator in the 1000 MW unit of a power plant,to study the flow field,corona electric field and particle motion field.The flow field was simulated using the k-ε double equation,the corona electric field was simulated using the finite volume method and the particle phase motion was simulated using the Lagrangian method.The SIMPLE algorithm was used for numerical calculation.Under the premise of verifying that the numerical simulation results were correct,the effects of outlet pressure,the velocity of flue gas,dust concentration and dust particle size on the dust removal efficiency of the electrostatic precipitator were simulated.The results show that the dust removal efficiency increases with the decrease of the absolute value of the outlet pressure,and the electrostatic precipitator operates stably when the outlet pressure is maintained at-3 000 Pa^3 500 Pa.At a higher velocity of flue gas,the inertial force of the fly ash particles is increased,and the ability to escape the trapping of the dust collecting plate against the electric field force is enhanced,so that the dust collecting efficiency of the electrostatic precipitator is reduced.When the dust concentration of flue gas is maintained at 30 g/m^3,the efficiency of electrostatic precipitator is the highest.The larger the particle size of dust is,the higher the dust collection efficiency of electrostatic precipitato is,but the growth rate is slowed down.