SCR反应器入口增设槽型惯性分离器数值模拟及设计优化

Adding groove intertial separator at SCR reactor inlet:numerical simulation and design optimization

为避免选择性催化还原法(SCR)所用催化剂中毒,以及蜂窝状催化剂堵塞,在国电哈尔滨平南热电有限公司2×350 MW机组锅炉尾部水平段烟道加装槽型惯性分离器,并采用计算流体力学方法研究了槽型惯性分离器内两相流场和分离性能;讨论了纵向排数、粒径和烟气流速对槽型惯性分离器性能的影响;结合典型超临界350 MW燃煤机组BMCR工况下的实际运行数据,分析了增设槽型惯性分离器后最上层催化剂的飞灰含量、最高流速及气流均匀度。结果表明:飞灰进入槽型惯性分离器内部,受到气流干扰较小,容易捕集;分离器性能受其形状、节距等结构因素影响,且纵向相对节距存在最佳值;通过多指标正交实验优化得到分离器结构最佳参数为深宽比为0.5,横向相对节距为2.5,纵向相对节距为2.5,纵向排数3,在压力损失为360.21Pa时,分离效率可达55.285%。

In order to avoid catalysts toxicity during selective catalytic reduction（SCR）process and reduce blockage of honeycomb catalysts,groove inertial separators were installed in the horizontal flue duct of the2×350 MW unit boiler in Harbin Pingnan Thermal Power Plant.The computational fluid dynamics method was used to numerically simulate the two phase flow in the groove inertial separators and investigate the separation performance.Moreover,the effects of lengthwise row number,particle size and flue gas velocity on performance of the groove inertial separator were discussed.Combing with the actual operation data of a typical supercritical 350 MW coal-fired unit,the fly ash content in the top catalyst layer,the highest flue gas velocity and gas uniformity in the duct after the groove inertial separator were analyzed.The results show that,after entering the groove inertial separator,the fly ash subjects small disturbance form the stream and is easy to be captured.It could be conclude that the most important structural parameters of the separator include aspect ratio and pitch,and the optimal lengthwise dimension pith is proposed.The optimal parameters of the separator are：the ratio of depth to width is 0.5,the transverse relative pitch is 2.5,thelengthwise relative pitch is 2.5,the longitudinal row number is 3.With these structural parameters,the separation efficiency can reach up to 55.285% when the pressure loss is 360.21 Pa.