摘要
在2.5MW(t)内循环流化床锅炉中试装置上,用自制的传热测试管,进行内置床换热器内传热状况的测定与分析。试验测量换热器中埋管管束表面与床层间的换热系数,研究了流化风速、颗粒粒径、床层温度对平均换热系数的影响规律,分析了埋管表面周向局部对流换热系数的分布状况。结果表明:当换热器内流化风速较小时,换热系数随风速的增加而变大,到达最佳流化风速时,换热系数达到最大值,之后随着风速的增加,换热系数稍有降低,然后趋于定值;颗粒粒径越小,对埋管表面的换热效果越好;埋管表面换热系数随床层温度的升高而增大;埋管的背风面换热系数总体大于迎风面,且随着风速的增加,分布趋向于均匀。针对此型内循环流化床内置床换热器中水平埋管,提出了其表面换热系数的试验关联式,较好地将试验值与预测值的偏差控制在25%以内。
In a 2.5MW（t） pilot internally circulating fluidized bed reactor, heat transfer coefficient between immersed tubes and bed materials in the in-bed heat exchanger was measured with help of heat transfer probes. The influences of fluidized velocity, particle diameter and bed temperature on convection heat transfer coefficient were investigated, and the local convection heat transfer coefficient around tube surface were studied as well. Results show that the convection heat transfer coefficient increases quickly with the fluidized velocity when the velocity is not high, and reaches its maximum value at 1.9~2.5 times of the minimum fluidized velocity and then decreases a little and keeps constant. Small particles can get more contact area at the tube surface, so heat transfer is enhanced. With the bed temperature increasing, the convection heat transfer coefficient increases. The local convection heat transfer coefficient in the leeward side of the tube is higher than that in the windward side due to the fluidized velocity and tube bundle structure, and the heat transfer coefficient distribution around tube surface changes with fluidized velocity increasing. A comprehensive correlation was proposed based on the experiment data and the results calculated from the correlation agree well with the results of experiments.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2016年第8期2181-2187,共7页
Proceedings of the CSEE
基金
"十二五"国家科技支撑计划项目(2012BAA02B01-02)~~
关键词
流化床
内置床换热器
水平埋管
换热系数
试验关联式
circulating fluidized bed
in-bed heat exchanger
horizontal tubes
heat transfer coefficient
experimental correlation
