工业燃烧室天然气湍流扩散火焰长度影响因素分析

Analysis of influencing factors of natural gas turbulent diffusion flame length in industrial combustion chamber

通过1.3MW级工业燃烧器实验验证商用CFD软件计算天然气湍流扩散火焰长度的有效性。以天然气(含有95%CH4和5%N_(2))为燃料,以直径为300mm、长度为1200mm的圆筒形燃烧室中、燃气孔径基本尺寸2mm的同轴射流扩散火焰为研究对象。采用数值计算的方法研究了燃气流量、喷孔孔径、助燃风特性等多种因素对火焰长度的影响规律。研究结果表明:在天然气湍流扩散火焰中,当孔径不变燃气流量增加一倍,火焰长度由652mm增加到782mm,增长19.9%。当燃气流量不变孔径增加一倍,652mm增加到1012mm,增长55.2%。改变燃气孔径是控制湍流扩散火焰长度的有效手段;在一定氧含量范围内,与助燃风氧含量相比,湍流火焰长度对助燃风速度的变化更加敏感。该研究对评估天然气燃烧装备性能和优化燃烧室设计具有重要的应用价值。

Via experimental validation with a 1.3MW industrial burner,the commercial CFD software in calculating natural gas turbulent diffusion flame length was verified.A coaxial jet diffusion flame in a cylindrical combustion chamber(diameter of 300mm and length of 1200mm)with a diameter of 2mm gas nozzle was studied,using the natural gas containing 95%CH4 and 5%N_(2).The influences of gas flow,nozzle diameter,and combustion air characteristics on the flame length were studied by numerical simulation.The results indicated that in the natural gas turbulent diffusion flame when the gas flow rate was doubled with the gas nozzle diameter unchanged,the flame length increases from 652mm to 782mm,with an increase of 19.9%.When the gas flow rate was unchanged with the nozzle diameter doubled,the flame length increases from 652 mm to 1012 mm,an increase of 55.2%.Changing the gas nozzle diameter was an effective means to control the length of turbulent diffusion flame.Within a specific range of oxygen concentration,the turbulent flame length was more sensitive to the velocity than the oxygen concentration of combustion air.The analysis had important application value for evaluating the performance of natural gas combustion equipment and optimizing the combustion chamber design.