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Suspended surface heat transfer in a large circulating
fluidized bed boiler furnace |
HUANG Chen1, CHENG Le-ming1, ZHOU Xing-long1, WU Chao-gang2,
ZHOU Qi2, FANG Meng-xiang1, LUO Zhong-yang1 |
1. State Key Laboratory of Clean Energy Utilization, Institute for Thermal Engineering,
Zhejiang University, Hangzhou 310027, China; 2. Dongfang Boiler Group Co., Ltd. Chengdu 611731, China |
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Abstract For rational design and safe operation of a large CFB boiler, heat transfer of suspended surface was studied experimentally in a CFB cold test rig with six cyclones and a pant-leg. An electric heated copper plate, the heat transfer probe was hung at the top region to simulate suspended surface in the furnace. The results show that the solids has high suspension density and they fall downward slowly along the suspended surface. The measured heat transfer coefficient increases with solids suspension density and it is not influenced significantly by the superficial gas velocity. The velocity mainly influences the heat transfer coefficient due to its impact on solids suspension density. Heat transfer mechanism was studied by a revised cluster renewal model. The model computation indicates that the average fraction of the surface area covered by clusters increases with the solids suspension density. This results in higher heat transfer coefficient.
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Published: 11 December 2012
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大型循环流化床炉内悬吊受热面传热特性
为了大型循环流化床锅炉的合理设计和安全运行,针对炉膛顶部悬吊受热面的传热特性,在六分离器、裤衩腿结构的循环流化床冷态试验台中采用电加热模拟受热屏进行实验研究,并基于颗粒团更新模型分析传热机理.实验结果表明：炉膛顶部悬吊屏表面固体颗粒浓度较大,固体颗粒以较小的速度贴壁向下运动；悬吊屏传热系数随着炉顶悬浮密度的增大而增大,炉膛空截面风速对传热系数影响不大,但通过改变炉膛悬浮密度进而改变悬吊屏传热系数.利用修正的颗粒团更新传热模型计算结果表明：当固体颗粒浓度增大时,悬吊屏表面颗粒团覆盖率增大,从而引起对流传热系数增大.
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