二次风率对烟气自循环燃气燃烧器性能的影响

Effect of Secondary Air Ratio on the Performance of a Gas Burner with Flue Gas Self-Recirculation

分别采用粒子成像测速(PIV)和数值模拟对自行设计的烟气自循环燃气燃烧器的冷态流场结构进行了研究,并模拟了燃烧器的热态燃烧特性。结果表明:二次风率是影响燃烧室内部速度分布及流动特性的一个重要因素,在较小的二次风率时,一次旋流空气旋流作用相对强烈,中心区域的轴向速度和径向速度均较高;燃烧器出口速度随轴向距离的增加逐渐衰减,在下游区域存在一个速度发散区;随着二次风率的增加,烟气的自循环倍率增加,燃烧室内的高温区域变小,NOx的排放量也随之减小;采用烟气自循环使得燃烧器NOx含量显著降低。

Particle Image Velocimetry(PIV) technology and numerical simulation were respectively used to study the non-reacting flow field of a self-designed gas burner with flue gas self-recirculation, while the combustion characteristics of the burner were studied numerically. Results show that secondary air ratio has great influence on velocity distribution and flow characteristics inside the combustion chamber. When the secondary air ration is samll, the swirl effect of primary air is relatively strong and axial and radial velocity of the central zone is relatively high. Velocity decays along the axial dirction, and there is a low speed aera in the downstream. With the increase of seondary air ratio, the recirculated ratio of flue gas also increased, while the aera of high temperature and the NOx emissions decrease significantly, indicating the use of flue gas self-recirculation can achieve low NOx emissions.