两段加热式双联火道内燃烧特性的数值模拟

Numerical Simulation of Combustion Characteristics in a Two-stage Heated Twin Fire Channel

【目的】分段加热耦合废气循环在大型焦炉中应用较广,但对空气过量系数和配风比的优化研究不足。【方法】利用CFD方法研究了不同过量空气系数和配风比下焦炉煤气在两段加热式双联火道中的燃烧特性。【结果】结果表明,配风比为65∶35时,各可燃组分的消耗速率最低,最高温度沿高向的衰减最少,温度均匀性最好。且在过量空气系数α≤1.35的范围内,高向温度呈现相似的分布。其中,α=1.25时火焰温度最低。NO_(x)浓度随配风比的增加而提高,随α增加而降低。综合分析,α=1.25与配风比65∶35组合形成的空气供给方式最好。焦炉煤气中的不同可燃组分的消耗速率不同,氢气最快,CO最慢。如将氢气分离用于发展氢能产业,剩余可燃组分形成的火焰会更长,有利于改善高度方向温度分布均匀性。

【Purposes】Segmented heating coupled exhaust gas circulation is widely used in large coke ovens,but the optimization of air excess coefficient and air distribution ratio is insufficient.【Methods】In this paper,the CFD method was used to study the combustion characteristics of coke oven gas in the two-stage heated duplex fire channel under different excess air coefficients and air distribution ratios.【Findings】The results show that when the air distribution ratio is 65∶35,the consumption rate of each combustible component is the lowest,the attenuation of the highest temperature along the high direction is the least,and the temperature uniformity is the best.The high temperature shows a similar distribution in the range of excess air coefficientα≤1.35.Among them,the flame temperature is the lowest whenα=1.25.NO_(x) concentration increases with the increase of air distribution ratio and decreases with the increase ofα.According to comprehensive analysis,the combination ofα=1.25 and air distribution ratio of 65∶35 forms the best air supply mode.The different combustible components in coke oven gas have different consumption rates,with hydrogen being the fastest and CO the slowest.If hydrogen separation is used to develop the hydrogen energy industry,the flame formed by the remaining combustible components will be longer,which is conducive to improving the uniformity of altitude direction temperature.