Numerical study of NOx emission reduction by MILD and air staged synergistic combustion in a new type of coke oven flue

• Published in: International communications in heat and mass transfer 2024-12, Vol.159, p.107986, Article 107986
• Main Authors: Shi, Kejian, Feng, Junxiao, Yang, Gang, Chen, Weiwang, Hong, Jichao, Yang, Huachao, Xu, Qian
• Format: Article
• Language: English
• Subjects: Air mass flow ratio; Air-staged combustion; MILD combustion; NOx emissions; Synergistic combustion
• ISSN: 0735-1933
• DOI: 10.1016/j.icheatmasstransfer.2024.107986

In order to address the issue of high emissions in the coke industry, we require innovative solutions. This article designs a coke oven flue with an array type secondary air nozzle, achieving the synergistic occurrence of MILD combustion and air staged combustion, which can significantly reduce nitrogen oxide emissions. However, further research is needed on the optimal control methods for synergistic combustion effects. First, Analyzed the mixing state of air and fuel under different air mass flow ratios. Next, by taking into account the oxygen distribution law, analyze the temperature distribution in both the primary and secondary combustion zones. Finally, analyze the distribution of NOx concentration. Study the impact of temperature differences caused by air mass flow ratio in synergistic effects on NOx emissions. The results indicate that by adjusting the air flow ratio, the air vortex intensity in the collaborative combustion process can be enhanced. This method can reduces flame temperature, achieving the objective of reducing NOx concentration. In the new type of coke oven flue, when the air mass flow ratio is 0.4, the combustion state in the primary and secondary combustion zones is optimal, and the NOx emission concentration is 312.88 mg/m3, representing a reduction of 38 %. •Studied the synergistic mechanism of MILD combustion and air-staged combustion.•Discussed the influence of air mass flow ratio on the reduction of NOx in synergistic combustion.•Obtained the optimal synergistic combustion parameters for minimum NOx emissions.