300 MW CFB锅炉旋风分离器改造数值模拟研究

Numerical simulation study on the enhancement of cyclone separator in CFB boilers

旋风分离器分离性能会显著影响循环流化床锅炉的运行。为解决某300 MW循环流化床锅炉旋风分离器分离器性能差的问题,基于欧拉-拉格朗日框架,使用UGNX12.0软件对该300 MW循环流化床锅炉的炉膛、旋风分离器、返料阀按照实际尺寸1∶1建立全回路几何模型,根据实际参数设置边界条件,并通过Barracuda软件进行数值模拟,分析旋风分离器烟道入口各参数(入口烟道高度、入口烟道宽度、入口下倾角大小及中心筒插入深度)对旋风分离器效率及压降的影响;综合考虑分离器的分离效率、压降以及磨损量,提出了2个改造方案。仿真结果表明:炉膛内压力模拟值与实际值的偏差均在5%以内,模拟结果较为精确;2个方案在各负荷下均能提升旋风分离器分离性能,方案1满负荷下效率相较于较改造前提升了0.260%,压降降低了13.1 Pa,方案2满负荷下效率相较于改造前提升了0.240%,压降降低了53.7 Pa;随着负荷降低,旋风分离器效率提升逐渐不明显,在300、260和160 MW负荷下,方案1分别提升0.263%、0.178%和0.023%,方案2分别提升0.243%、0.174%和0.020%。

Cyclone separator separation performance can significantly affect circulating fluidized bed boiler operation.In order to solve the problem of poor separator performance of cyclone separator in a 300 MW circulating fluidized bed boiler,based on the Euler-Lagrange framework,firstly,a full loop geometric model of the furnace,cyclone separator and return valve of the 300 MW circulating fluidized bed boiler was established by ug software according to the actual size of 1:1,and then the boundary conditions were set according to the actual parameters,and then numerical simulation was carried out by Barracuda software.Numerical simulations were carried out by Barracuda software to analyze the effects of the flue inlet parameters of the cyclone separator:inlet flue height,inlet flue width,inlet downward tilt angle and the insertion depth of the center cylinder on the cyclone separator efficiency and pressure drop.The deviation between the simulated and actual values of the pressure in the furnace chamber is within 5%,and the simulation results are relatively accurate.Considering the separation efficiency,pressure drop and wear and tear of the separator,two modification schemes are proposed.Simulation results show that the two schemes can improve the cyclone separator separation performance at all loads,the efficiency of Scheme I at full load is improved by 0.26%and the pressure drop is reduced by 13.1 Pa compared with that before the retrofit,and the efficiency of Scheme II at full load is improved by 0.24%and the pressure drop is reduced by 53.7 Pa compared with that before the retrofit;with the reduction of the load,the efficiency improvement is not obvious gradually,and the efficiency improvement is not obvious at 300 MW,260 MW and 160 MW loads,Scheme I improves the efficiency of the separator by 0.26%,0.178%,and 0.023%,respectively,and Scheme II improves it by 0.24%,0.174%,and 0.02%,respectively.