燃煤电站直排烟囱二次脱水流场模拟与优化

摘要

在燃煤电站湿法脱硫直排烟囱内加装二次脱水装置,可较好地解决烟囱飘雨问题.为分析加装二次脱水装置前后烟囱出口含水率和内部流场的变化,并优化装置结构,使脱水率和运行阻力达到最佳匹配,采用CFD方法对烟囱内部流场进行数值模拟研究.结果表明:加装二次脱水装置后,烟囱出口烟气含水率由111 mg/m3减小到52 mg/m3;,运行阻力在允许范围内增大,由195 Pa增大到699 Pa,小于1 200 Pa;烟囱出口速度由17.3 m/s增大到17.6 m/s;烟气沿烟囱内壁螺旋上升,而不再是沿中心区域直线上升;旋流板最佳叶片角度为42°.通过实际和模拟对比分析,验证了二次脱水装置的有效性和最佳叶片角度的可行性,得到烟囱内部流动基本规律和特性曲线.%The "chimney rain" problem can effectively be solved by adding a secondary dehydration device inside the chimney with wet flue gas desulfurization (FGD) direct-discharged measures in coal fired power station.In order to analyze the changes of outlet moisture content and internal flow field,and to optimize the structure of device to match the dehydration capacity and working resistance,a computational fluid dynamics (CFD) method was adopted to simulate the internal flow field of the chimney.Results show that after installing a secondary dehydration device the outlet moisture ratio decreases from 111 mg/m3 to 52 mg/m3 ;the working resistence increases in an allowable range,from 195 Pa to 699 Pa,which is below 1 200 Pa;the outlet velocity raises from 17.3 m/s to 17.6 m/s.The smoke spirals up along inwall,not along central zone ; the optimum angle of the whirl board is 42 degrees.Through the comparative analysis of actual and simulation results,the effectivity of the device and the feasibility of optimum angle were verified,and the basic laws and characteristics curves of internal flow field were also obtained.