宽筛分床料循环流化床与水平管之间的换热特性研究

本文在试验研究的基础上.对宽筛分床料循环流化床与水平管之间的换热特性进行了较为深入细致的分析与研究,得到了一些非常有价值的结果.

Experimental Studies of Heat Transfer in Multiparticle Circulating Fluidized Beds

Experimental results concerning the heat transfer in circulating fluidized beds have been obtained.Three kinds of bed materials with different sizes have been used in the experiments, The diameter of the first kind ranges from o to 3 mm and the average diameter is 1.97 mm; that of the second kind ranges from o to 2 mm and the average diameter is 0. 85 mm while that of the third kind ranges from o. 7 to 1.1 mm and the average diameter is 0.87 mm. From these experiments we have come to the conclusion that the heat transfer in a circulating fluidized bed is quite different from that in a conventional fluidized bed.In circulating fluidized beds the local heat transfer coefficient on the windward side of horizontal tubes is affected by fluidization velocities and the local heat transfer coefficient on the leeward side is also very much affected because of the solid reflux controlled by fluidization velocities and solid concentrations. It can also be concluded that the heat transfer coefficient increases from the center to the wall of the bed owing to the increase of solid concentration and decreases from the bottom to the top of the bed owing to the decrease of solid concentration along the bed height.