CFB锅炉一次风室送风口改进设计与气流分布特性的研究

Improvement Design for Primary Chamber Inlet Area and Air Current Distribution Characteristic Analysis of CFB Boiler

针对循环流化床锅炉布风板存在比较严重的漏渣现象,在对其漏渣原因进行分析的基础上,采用kε-双方程模型对一次风室的流场进行了数值模拟。模拟结果显示:一次风进入一次风室后,由于风口与边界之间、两个一次风口之间间距较大,在射流卷吸作用下,一次风入口和边界以及两个入口之间形成较大的回流区,气流向下运动,抽吸炉渣造成布风板漏渣。为了有效地控制布风板漏渣,提出了采用在一次风口内加装散流器的改进方案,并进行了数值模拟。模拟结果显示:改型后,使一次风室内大回流区变小,在布风板下形成较宽的静压层。在风口附近压力比较小,随着气流的扩散,动压逐渐转变成静压,静压力逐渐变大,布风板处压力分布均匀,避免了气流向下的抽吸现象,比较能改善漏渣问题。

The slag leakage from the air distributor of circulating fluidized bed is serious. The reason is analyzed and the flow field of the primary wind chamber is simulated by using k-epsilon model. The result of numerical simulation shows that when the wind enters the primary chamber, a large circumfluence region is formed with the effect of jet flow whirlpool due to the big distance between the outlet of the primary and boundary and the long distance between two primary wind outlets. Thus the air current which carries the slag flows down to the air distributor and results in slag leakage. In order to control the leakage effectively, a diffluent device is fixed on the outlet of the primary wind and the corresponding flow field is simulated. The numerical simulation result demonstrates that with the diffluent device, the circumfluence area becomes shrinked and a rather wide static pressure level is formed under the air distributor and the pressure is quite small near the wind outlet. Along with the air current dispersion, the dynamical pressure gradually transforms to the static pressure, and the static pressure gradually becomes bigger, the pressure distribution around the air distributor is rather even. Therefore the pumping down of air current is eliminated, which can prevent the slag from leaking.