逆向射流燃烧技术研究进展

逆向射流燃烧技术是可同时适用于燃气和燃煤领域的高效低污染燃烧技术,逆喷结构和射流流速比决定了其流场特性。笔者综述了逆向射流燃烧技术在燃气和燃煤领域的发展历史、研究现状和发展趋势。在燃气领域,逆向射流主要起稳定火焰作用,具有良好的燃料-空气混合条件,形成一个近似均匀的热流场,避免燃烧过程中出现局部热点,但目前仅为一种为燃气轮机和飞机发动机提供的探索性技术,工程应用还需克服燃料和空气在一个狭小空间里的流场合理控制以及从简化装置到工程放大等问题。在燃煤领域,对于煤粉燃烧器,逆向射流可形成一个可控组分、大小、形状和位置的回流区,且将煤粉直接送进回流区,还可控制煤粉在回流区内的停留时间,该技术与传统火焰稳定方式相比,火焰稳定能力更强、停留时间更长、污染更低,更适用于低阶煤的高效燃烧,目前,逆向射流燃烧技术耦合其他稳燃、低氮技术为煤粉高效清洁利用发展提供了新方向,且已有实际工程应用,但对于其机理研究不够深入,限制了其进一步发展与推广。对于电站锅炉,部分一次风或燃尽风逆向偏转射入炉内,可缓解四角切圆燃烧方式下炉膛出口烟气的烟速和烟温偏差,目前主要是燃尽风反切的工业应用,但如何合理控制燃尽风反切角度、反切动量以及反切层数等关键问题还需进一步研究。 Reverse jet combustion technology is a high-efficiency and low-pollution combustion technology,which can be applied to both gas and pulverized coal combustion.The flow characteristics are determined by the structure of reverse jet and jet velocity ratio.In this paper,the development history,research progress and development trend of reverse jet combustion technology in gas and coal-fired fields were reviewed in detail.The analysis shows that in the field of gas combustion,the reverse jet is mainly used to stabilize the flame,which is characterized by good fuel/air mixing conditions,forming a nearly uniform heat flow field and avoiding local hot spots in the combustion process.However,it is only an exploratory technology for gas turbine and aircraft engine at present.For engineering application,it is necessary to overcome some important problems,such as the reasonable control of the flow field of fuel and air in a narrow space,as well as from the simplification of the device to the enlargement of the project.In the field of coal combustion,for the pulverized coal burner,the reverse jet can form a recirculation zone with controllable components,size,shape and position.It also can directly send the pulverized coal into recirculation zone and control the residence time of pulverized coal in the recirculation zone. Compared with the traditional flame stabilization method,the technology has stronger flame stability,longer residence time and lower pollution,which is more suitable for the high efficiency of low rank coal combustion.At present,the reverse jet combustion technology coupled with other stable combustion and low nitrogen technology provides a new direction for the development of high-efficiency and clean utilization of pulverized coal,and has been applied in practical engineering.But the mechanism research is not in-depth,which limits the further development and promotion of the technology.For utility boilers,part of the primary air or burn-out air is deflected into the furnace in reverse direction,which can alleviate the velocity and