摘要
喷淋降温冷却技术具有传热效率高、结构紧凑等优点在湿烟羽治理中广泛应用。以单液滴运动为基础,构建喷淋降温过程中传热传质模型。研究喷淋塔内液滴的沉降规律;考察雾化参数、液气比、流动形式、停留时间等对液滴升温规律及液滴粒径演化规律的影响,并构建用于指导喷淋塔内换热时间选型的相图。结果表明:逆流布置方式下,雾化粒径较大(0.0015m)液滴在宽烟气流速范围内(1~5m/s)均不被携带;喷淋塔内对流冷凝宏观换热系数约265.5~512W/(m^2·℃);液气比约3.5-7.5L/m^3。喷淋塔内液滴浓度高于2.0×10^6/m^3时,冷却水出口温度主要受停留时间限制;液滴浓度低于2.0×10^6/m^3时,冷却水出口温度受停留时间和液滴浓度同时限制。研究结果可为喷淋塔的结构设计及工艺优化提供理论支持。
Spray cooling technology is widely used for deep cooling of the wet flue gas, because of its excellent heat transfer efficiency and compact heat exchanger structure. Based on the mechanism of droplet movement in the spray tower, a heat and mass transfer model was established. The effects of droplet settling velocity as well as the atomization parameters, liquid-gas ratio, flow pattern and the residence time on droplet heating and size growth behaviors were all investigated. In addition, phase diagrams of droplet residence time at different cooling water temperatures were presented. The results indicate that the droplet with a bigger diameter(0.0015 m) will not be carried by the flue gas at a wide range of velocity(1~5 m/s). The convective condensation heat transfer coefficient is about 265.5~512 W/(m^2·℃) and the liquid gas ratio is about 3.5~7.5 L/m^3 of the counter-flow spray tower. When the droplet concentration is higher than 2.0×10^6/m^3, the temperature of the outlet cooling water is restricted to the residence time of droplets in the spray tower, and when the droplet concentration in the spray tower is lower than 2.0×10^6/m^3, the temperature of outlet cooling water is restricted to the residence time of droplets in the spray tower and droplets concentration. All these results provide important reference and theoretical support for spray cooling tower design and process optimization.
作者
王翔
张泽昊
廖增安
李水清
WANG Xiang;ZHANG Zehao;LIAO Zengan;LI Shuiqing(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University,Haidian District,Beijing 100084,China;Fujian Longking Co.,Ltd.,Longyan 364000,Fujian Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2020年第8期2578-2586,共9页
Proceedings of the CSEE
基金
国家重点研发计划项目(2016YFB0600602)。
关键词
湿烟气
喷淋降温
液滴
传热传质
wet flue gas
spray cooling
droplet
heat and mass transfer
