低浓度甲烷旋流燃烧器性能数值模拟

Numerical simulation of performance of low concentration methane cyclone burner

为了解决煤层气中低浓度甲烷燃烧利用问题,基于贫燃预混、旋流燃烧等方法,运用传统导向叶片的成型原理提出一种新型旋流叶片.采用数值模拟研究了叶片的结构参数对燃烧器性能的影响.结果表明:随着叶片内径、包络角、数量和出口角增大,旋流强度增大,火焰的形状由细长向短粗转变,火焰向燃烧室中轴线靠近;未燃烧的混合气与高温烟气接触后可以更快达到燃烧温度,燃烧效率提高.但叶片包络角达到90°后,再次增大包络角,燃尽率稳定在98.2%.叶片内径增大,燃尽率先增大后减小,这是因为随着叶片出口速度的增大,混合气在高温区的停留时间反而减少,燃料燃烧效率下降.

In order to solve the problem of combustion and utilization of low concentration methane in coal bed methane,a new type of cyclone blade is proposed based on the methods of lean combustion premixing and cyclone combustion and the forming principle of traditional guide blade.The influence of the structural parameters of the blade on the performance of the burner is studied by numerical simulation.The results show that with the increase of blade inner diameter,envelope angle,number and outlet angle,the swirl intensity increases,the shape of flame changes from slender to short and thick,and the flame approaches the central axis of the combustion chamber.The unburned mixture can reach the combustion temperature faster after contacting with high temperature flue gas,and the combustion efficiency is improved.However,when the blade envelope angle reaches 90°,with the envelope angle increasing again,the burnout rate is stable at 98.2%.As the blade inner diameter increases,the burnout rate first increases and then decreases.This is because with the increase of the blade outlet velocity,the residence time of the mixture in the high temperature zone decreases,and the fuel combustion efficiency decreases.