垂直浓淡煤粉燃烧方式下炉内拟序结构研究

A Study of the In furnace Coherent Structure under a Vertical Bias Pulverized coal Combustion Mode

采用PDA测量系统 ,对四角切圆锅炉中垂直浓淡煤粉燃烧方式下影响一次风与主流场混合和扩散的炉内拟序结构进行了实验研究和湍流特性分析。结果表明 ,一次风射流由于与上游横向射流的相互作用 ,在背火侧形成尾迹涡 ,在向火侧形成剪切涡 ,其中尾迹涡和剪切涡中有较高的湍动能和剪切应力 ,对颗粒的扩散起着主控作用。并从理论上分析了垂直浓淡煤粉燃烧技术可能不利于煤粉颗粒的燃尽 。

With the help of a particle dynamic analyzer (PDA) system an experimental and an alytical study of the turbulent flow characteristics has been conducted of the i n furnace coherent structure in a tangentially fired furnace under a vertical b i as pulverized coal combustion mode. The in furnace coherent structure can have a n effect on the mixing of the primary air with a main flow field. The results of t he above study show that the interaction of the primary air jet flow and the tra nsverse jet flow at the upper stream results in the formation of a wake eddy and a shear eddy respectively at the back of flame side and at the flame facing sid e. In this regard, there exists in the wake eddy and shear eddy a relatively hig h turbulent kinetic energy and shear stress, which may play a major role in cont rolling the diffusion of particles in the furnace. Based on a theoretical analys is the authors conclude that the vertical bias pulverized coal combustion mode c an give rise to certain conditions, unfavorable for the burn up of pulverized c o al particles, thus triggering the formation of slags on boiler water walls.