Characteristics of fouling development in shell-and-tube heat exchanger: Effects of velocity and installation location
Characteristics of fouling development in shell-and-tube heat exchanger: Effects of velocity and installation location
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DOI：
10.1016/j.ijheatmasstransfer.2014.05.031
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发表时间：
2014-10
影响因子：
5.2
通讯作者：
Chao Shen;C. Cirone;Liangcheng Yang;Yiqiang Jiang;Xin-lei Wang
中科院分区：
文献类型：
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作者：
Chao Shen;C. Cirone;Liangcheng Yang;Yiqiang Jiang;Xin-lei Wang
摘要本研究旨在探讨污水流速及管壳式热交换器安装位置对热交换器内颗粒污垢沉积的影响。三个长期的污垢测试与热交换器安装在不同的废水流量（低，中，高），和一个测试与热交换器安装在泵的吸入口在一个恒定的（中等）流量的泵的射击出口进行。对于每个测试测量传热系数和污垢阻力的变化，并且在每个测试结束时收集累积污垢的样品以确定其粒度分布。分析从每个测试情况收集的污垢的粒度分布，并与废水中颗粒的粒度分布进行比较。结果表明，沉积在管表面的颗粒粒径主要集中在1.5 ~ 88 μm之间。当流速为0.31 m/s（低速）、0.46 m/s（中速）和0.69 m/s（高速）时，污垢的平均粒径分别为40.8 μm、24.4 μm和18.6 μm。在低、中、高流速下，渐近污垢阻力分别为1.1 × 10−3、0.59 × 10−3和0.22 × 10− 3 m2 K/W。此外，在低和中等废水流速下，在污垢发展的开始时观察到负污垢阻力。结果还表明，换热器安装在泵吸入口时的渐近污垢阻力和污垢平均粒径均大于换热器安装在喷射口时的渐近污垢阻力和污垢平均粒径。平均而言，71%（按质量计）的污垢由灰成分组成。
The purpose of this study was to investigate the effects of wastewater velocity and installation location of a shell-and-tube heat exchanger on particle fouling deposited within the heat exchanger. Three long-term fouling tests with the heat exchanger installed at the shoot-outlet of a pump with varied wastewater flow rates (low, medium, and high), and one test with the heat exchanger installed at the suction-inlet of a pump at a constant (medium) flow rate were conducted. Variation of the heat transfer coefficient and fouling resistance was measured for each test and a sample of the accumulated foulant was collected at the end of each test to determine its particle size distribution. The particle size distribution of the foulant collected from each test case was analyzed and compared to the size distribution of particles in the wastewater. Results suggested that the diameters of particles deposited on the tube surfaces were mainly in the range of 1.5–88 μm. The average particle diameter of fouling was 40.8 μm at a velocity of 0.31 m/s (low), 24.4 μm at a velocity of 0.46 m/s (medium), and 18.6 μm at a velocity of 0.69 m/s (high). Asymptotic fouling resistances were 1.1 × 10−3, 0.59 × 10−3, and 0.22 × 10−3m2K/W respectively for the low, medium and high velocities. In addition, negative fouling resistances were observed at the beginning of fouling development with low and medium wastewater velocities. Results also showed that both the asymptotic fouling resistances and the average particle diameter of fouling obtained with the heat exchanger installed at the suction-inlet of pump were larger than that with heat exchanger installed at the shoot-outlet. On average, 71% (by mass) of fouling consisted of ash ingredient.