梯度磁场对甲烷层流燃烧时NOx生成特性的影响

Influence of gradient magnetic field on NO_x formation characteristicsin methane laminar burning

天然气燃烧过程中NOx的控制是燃烧洁净优化的关键指标之一。以甲烷层流扩散火焰为研究对象,通过在火焰周围安放电磁铁的方法在火焰区产生梯度磁场,开展在四种甲烷流量工况下改变梯度磁场对热力型NOx的生成特性的研究。研究发现,当梯度磁场增加时,较大磁场梯度对应的25mm高度火焰区的温度随之升高,而热力型NOx的生成量却不受温度升高的影响存在着明显减少的变化规律,与无磁场梯度工况相比,NOx最大时至少减少60%以上。经分析认为,梯度磁场施加给氧气顺磁力直接改变火焰周围氧气的流动传输特性,氧气的流运作用使得OH自由基向火焰区流动,生成HCN、HCCO抑制热力型NOx的生成。

The NO2 control in natural gas combustion process is one of the key indicators of clean burning optimization. With the methane laminar diffusion flame as the research object, the gradient magnetic field was generated in the flame zone through a solenoid placed around the flame. The thermal NO2 formation characteristics were researched by chaiaging gradient magnetic field under four methane flow conditions. Results have shown that the temperature of flame zone at the height of 25mm increases with the gradient magnetic increasing. On the contrary, the production of thermal NO~ obviously decreases with the gradient magnetic increases, and has nothing to do with temperature rising. Compared with no magnetic field gradient, the largest NO~ reduction is at least more than 60%. It can be seen that the paramagnetic force on oxygen applied by gradient magnetic field directly changes the oxygen transmission characteristics around the flame. The oxygen flow leads to the flow of OH radical towards the flame zone, the generation of HCN and HCCO and the thermal type NO2 formation is inhibited. This research explores a new method to control NO2 in combustion process.