异距贴壁风喷口布置方案的数值模拟

Numerical simulation of near-wall air scheme combined with different jet position

为了消除某600MW前后墙旋流对冲锅炉侧墙水冷壁出现的高温腐蚀现象,在前后墙开3层对冲贴壁风喷口,借助Fluent软件模拟计算了原始运行工况以及不同贴壁风工况下的炉内燃烧,并着重分析了侧墙近壁区内还原性气体(CO)浓度的分布情况;结果表明,数值模拟的结果比较符合炉膛实际的运行情况,不同贴壁风喷口类型的防腐效果并没有显示出太大差异;受上升烟气的携带作用,贴壁风喷口的布置方式对贴壁风的防腐效果影响很大;采用异距式贴壁风喷口的布置方式并结合贴壁风射流补氧特性,在贴壁风率消耗不到4%的前提下,就使侧墙近壁区的还原性气氛浓度达到较低水平,说明在合适的喷口布置以及速差组合的基础上,前后墙贴壁风布置方式可以有效地抑制侧墙水冷壁高温腐蚀。

In order to eliminate the high temperature corrosion of the side water-cooled wall in a600MW front and rear wall swirl-opposed firing boiler,three layers of opposed near-wall air nozzle were punched in the front and rear walls.The boiler combustion of original condition and near-wall air condition with different nozzle arrangement schemes was simulated by use of Fluent.The distribution of reductive atmosphere of near-wall region was emphatically focused on.The results showed that the simulation results agreed with the actual operation condition of boiler and the anti-corrosion performance of different nozzle patterns was limited.Due to the push of rising flue gases from the bottom,the nozzle arrangement had a great influence on the effect on anti-corrosion.In addition,by adjusting the position of nozzle and combining the nozzle flow characteristics,the coverage of reductive atmosphere in the near-wall region maintained at a low level while the ratio of near-wall air was less than4%,indicating that the front and rear wall arrangement scheme can effectively restrain the high temperature corrosion of the side water-cooled wall on the basis of the combination of appropriate nozzle positions and nozzle flow velocity.