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

Abstract

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 coefficient α≤1.35. Among them, the flame temperature is the lowest when α＝1.25. NOx concentration increases with the increase of air distribution ratio and decreases with the increase of α. According to comprehensive analysis, the combination of α＝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.

Keywords

• two-stage combustion
• twin fire channels
• air supply
• temperature
• nitrogen oxides