入口旋流数对煤粉低尘燃烧器流场的影响

The Influence of Inlet Swirl Number on the Flow Field of Pulverized Coal Slagging Burner

以液排渣旋风燃烧过程为基础的煤粉低尘燃烧器可在燃烧过程实现捕渣，为工业加热提供低含尘浓度的高温火焰，是工业加热过程实现以煤代油的先进燃烧技术。根据旋流燃烧流动特点，采用能考虑非均向湍流应力的雷诺应力模型，对旋流煤粉低尘燃烧器内气流流动过程场进行数值模拟计算，计算结果与流场实验测试相吻合。研究表明，气流进入燃烧器时的旋转强度（旋流数）对燃烧器内的流动特性有很大影响，在冷态模型条件下，当旋流数在7以上时，环室回流在轴向贯穿燃烧器整个流场，有利于增加煤粉颗粒在燃烧室内的循环次数，提高灰渣捕获率；低于7时，环室回流出现阻断，不再连续，易造成煤粉颗粒直接逸出，对燃烧及灰渣捕获不利。随旋流数增加，燃烧器出口处中心回流率增大，对炉膛高温烟气的抽吸作用增强。

The pulverized coal slagging burner with liquid slag-removal cyclone combustion can realize ash capture in combustion to provide high-temp. flame with low dust concentration in industrial heating. It is an advanced combustion technology in industrial heating to realize the use of coal in place of oil. A numerical simulation based on the Reynolds Stress Model for a pulverized coal Slagging burner is reported in this paper, and the calculation result tallies with experimental test. The results show that, there is a main backflow area along the axis of the burner, and an annular backflow area nearby the wall of burner, the inlet swirl number of secondary air influences the recirculation rate of flue gas. When the inlet swirl number is less than 7, the annular backflow would become discontinuous, and the ash capture rate would be reduced. With the increase of swirl number, the axis reflux rate increases and the suction power to the high temp. flue gas outside the burner increases.