燃煤与半焦混合燃烧过程中燃尽风配风位置对燃烧特性影响的模拟研究

Numerical Study on the Impact of Overfire Air Position on CombustionCharacteristics in the Co-firing Process of Coal and Semi-coke

以某2.4 MW旋流燃烧炉为研究对象,基于数值模拟研究了煤粉与半焦混合燃烧过程中燃尽风配风位置对燃烧特性的影响。结果表明:燃尽风配风位置对燃尽特性有显著的影响,燃尽风配风位置越靠近主燃区下游,燃料在主燃区的停留时间越长,在燃尽区的停留时间越短,未燃尽焦炭反应越不充分,其燃尽程度越差。因此,在实际运行或改造中,在确保氮氧化物(NO_(x) )排放满足要求的情况下,建议尽量使燃尽风配风位置靠近主燃区,该方式有利于改善半焦的燃尽特性。

The effects of the overfire air position on the combustion characteristics during the co-firing process of coal and semi-coke were studied numerically at a 2.4 MW swirl combustion furnace. Results show that, the overfire air position has a significant effect on the burning-out characteristics. The closer the overfire air is positioned to the downstream of the primary combustion zone, the longer residence time the fuels experience in the primary combustion zone and the shorter time in the overfire zone, which causes the inadequateness of reaction and worsens the burning-out of the remaining coke. Therefore, it is recommended that the overfire air position should be set as close as possible to the primary combustion zone with ensuring the nitrogen oxide (NO_(x) ) emission meets the requirements in actual operation or retrofit. This method is beneficial to improve the burning-out characteristics of semi-coke.