炉膛煤粉空气射流的火焰稳定性分析

本文结合锅炉炉膛煤粉空气射流的流场特征,分析煤粉气流的预热、着火及燃烧过程,提出以炽热燃烧的回流区为研究对象的分析煤粉射流气流火焰稳定的集总分析模型,并用它分析了几种典型的炉膛煤粉射流流场.结果表明,对于任何给定特征尺度的回流区只要满足一定的温度、煤粉浓度及射流速度等条件,就能实现对射流火焰的稳定.

A Flame Stability Analysis for Pulverized Coal-Air Jet in Furnace

The flame stability of the coal-air jet in the combustion of low-grade pulverized coal has all along been a problem of public concern. A number of new-type burners have been designed and fairly successfully used in stabilizing the flame in a furnace. Nevertheless, the mechanism of flame stabilization has yet to be studied. In this paper, the flow characteristics of the coal-air jet are considered for a better understanding of the preheating, igniting and combustion of the coal-air mixture. A lumped system model based on the well-distributed flowfeature of the recirculating zone formed by the jet is proposed for analyzing the flame stabilization of the coal air jet. Four kinds of flow field, the suddenly expanded channel one, the corner-fired burner one, the side-fired burner one and that of the fired burner with a bluff-body, have been investigated with the model developed. It is concoluded that, for a recirculating zone brought about by any kind of jet of given characteristic size, it is possible to stabilize the flame of the coal-air jet on condition that the temperature in the recirculating zone, the velocity of the jet and the concentration of pulverized coal are within a specified range.