降低天然气蓄热式辐射管烟气中NOx的实验

Decreasing of NO_x Emission in Fired-natural Gas Radiant-tube with Regenerative Combustor

天然气蓄热式辐射管可将助燃空气预热到接近1 000℃,如果不采取一些特殊的措施,烟气中NOx含量会很高。文中通过实验手段,研究了降低天然气蓄热式辐射管的NOx含量的措施,指出分级燃烧、烟气再循环、强化辐射管内传热等技术可有效的控制辐射管中NOx的生成。研究认为,进一步降低NOx含量,有两种方式可选择:一是在辐射管设置内衬管,同时通过加插入件,强化辐射管内燃烧的高温气体与管壁的传热来降低燃烧温度,从而降低NOx含量,并且该方法还有降低排烟温度的好处;二是在设置内衬管的基础上,通过烟气再循环,降低辐射管燃烧区的O2含量,减少NOx含量,且烟气再循环还有改善辐射管表面温度均匀性的效果。

Air can be preheated nearly 1 000 ℃ in the fired-natural gas radiant-tube. Normally, there is high NOx emission in the exhaust gas. We propose that staged combustion, recirculation of exhaust gas, and heat transfer could reduce NOx emission. There are two efficient approaches, which can be used to reduce NOx emission. The first one is combination of staged combustion and heat transfer. This can not only reduce NOx emission, but also decrease the temperature of exhaust gas. The other is combination of the staged combustion and recirculation of exhaust gas, which can decrease the concentration of O2 in the tube, and thus decrease NOx emission. This can distribute surface temperature of the radiant-tube as well.