基于CFD方法的燃煤电厂烟气排放数值模拟

发布时间：2018-06-01 11:55

本文选题：计算流体力学 + 燃煤电厂　；参考：《环境科学研究》2017年12期

【摘要】：为研究燃煤电厂的烟气扩散,采用计算流体力学(computational fluid dynamics,CFD)方法对燃煤电厂烟气排放中污染物(包含气态污染物和固态颗粒物)的扩散形态进行模拟.燃煤电厂的排烟方式主要有烟塔合一和烟囱两种,根据几何参数建立烟塔合一及烟囱的数值模型,采用纳维-斯托克斯方程(Navier-Stokes equations,N-S equations)求解流场及气态污染物浓度场,采用离散相模型(Discrete Phase Model,DPM)计算固态颗粒污染物运动轨迹.结果表明:对于气态污染物,由于冷却塔下游漩涡的卷吸作用,采用烟塔合一排放的烟气最大浓度和超标范围随环境风速的增加逐渐增大,不利于烟气扩散.但随着环境风速的增加,空气的对流作用逐渐增强,从而加速了烟气的扩散.在漩涡和环境风的综合作用下,烟气的最大浓度和超标范围在环境风速为6m/s时达到最大值,随后随着环境风速增加而减小.采用烟囱排放的烟气由于漩涡作用很小,因此其最大浓度及超标范围随风速的增加呈递减趋势.得益于烟气在冷却塔内的预扩散,采用烟塔合一排放的烟气最大浓度比采用烟囱排放的烟气最大浓度低将近1个数量级,但这种优势会随着环境风速的增加而减小.对于固态污染物,冷却塔后方的漩涡会加速颗粒物的扩散,因此采用烟塔合一排放的颗粒物的扩散状态远优于采用烟囱排放的颗粒物的扩散状态.
[Abstract]:In order to study flue gas diffusion in coal-fired power plants, the diffusion patterns of pollutants (including gaseous pollutants and solid particles) in flue gas emissions from coal-fired power plants were simulated by computational fluid dynamics (CFD) method. There are two types of exhaust gas in coal-fired power plants: smoke tower integration and chimney. According to the geometric parameters, the numerical model of smoke tower integration and chimney is established. The Navier-Stokes equations Navier-Stokes equationsN-S equationsare used to solve the flow field and the concentration field of gaseous pollutants. Discrete Phase Model (DPM) was used to calculate the motion trajectory of solid particle pollutants. The results show that, for gaseous pollutants, due to the entrainment of the vortex downstream of the cooling tower, the maximum concentration and exceeding range of flue gas emitted by the smoke tower increase with the increase of the ambient wind speed, which is not conducive to the smoke diffusion. However, with the increase of the ambient wind speed, the convection effect of the air increases gradually, which accelerates the smoke diffusion. Under the combined action of swirl and ambient wind, the maximum concentration and exceeding range of flue gas reach the maximum when the ambient wind speed is 6m/s, and then decrease with the increase of ambient wind speed. The maximum concentration and exceeding range of flue gas emitted by chimney are decreasing with the increase of wind speed because of the small swirl effect. Due to the pre-diffusion of flue gas in the cooling tower, the maximum concentration of flue gas emitted by the smoke tower is nearly one order of magnitude lower than that of the smoke from the chimney, but this advantage will be reduced with the increase of the environmental wind speed. For the solid pollutants, the swirl behind the cooling tower will accelerate the diffusion of particulate matter, so the diffusion state of the smoke tower emission is much better than that of the chimney emission.
【作者单位】：南京信息工程大学大气物理学院;国电环境保护研究院国家环境保护大气物理模拟与污染控制重点实验室;南京信息工程大学环境科学与工程学院;
【基金】：国家自然科学基金项目(41373023,91544229-02) 国家重大科学仪器设备开发专项(2014YQ060537)
【分类号】：X773

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