地形“狭管效应”影响下的空冷岛性能研究
发布时间：2019-02-18 16:12
【摘要】：为缓解北方地区水资源缺乏的情况,直接空冷系统被世界各国普遍采用,尤其在富煤缺水地区更是得到广泛应用。然而直接空冷系统换热器长期暴露在外,冷却介质是空气,所以周围空气的温度、风速变化对其换热能力以及正常运行有直接影响。直冷系统的换热性能对机组运行的经济性至关重要,背压的波动与机组运行安全性紧密相关,因此研究直接空冷系统受环境因素影响的性能变化十分重要。本文通过对某厂的地形进行考察研究发现,该厂直接空冷机组在常年风沙及各种空气中的杂质影响下,形成了一定管外结垢,直接空冷换热器性能逐年降低,该地环境温度夏季常年较高,对机组的背压有恶劣影响。而该厂厂址布置情况较为特殊,空冷岛两侧山峰构成了一条流道,而常年SSW风向的气流从流道的入口流入,直冷系统空冷岛位于流道中间,两侧流道形成了“狭管效应”,增大环境风速,但具体影响数值并未有过类似研究。因此将该厂直接空冷岛与两侧的山峰进行建模,通过数值模拟的方式分析风速变化时直接空冷换热能力改变与空冷岛区域流场的变化。本文针对环境风影响空冷岛换热性能的问题,结合间接空冷的抗自然因素变化影响能力以及喷射式凝汽器换热端差小的特点,提出了一种新型抽汽冷却方式,并将该种方式与传统喷淋方式冷却效果进行对比,发现这种冷却方式效果更为理想,最后对全文结论进行总结与展望。
[Abstract]:In order to alleviate the shortage of water resources in the northern region, direct air cooling system is widely used in the world, especially in the areas rich in coal and water shortage. However, the heat exchanger of direct air-cooling system is exposed for a long time, and the cooling medium is air, so the temperature and wind speed of the surrounding air have a direct effect on the heat transfer capacity and normal operation of the heat exchanger. The heat transfer performance of direct cooling system is very important to the economy of unit operation, and the fluctuation of back pressure is closely related to the operation safety of the unit, so it is very important to study the performance change of direct air cooling system affected by environmental factors. Based on the investigation of the topography of a factory, it is found that the direct air-cooled unit in this plant has formed a certain scale outside the tube under the influence of the annual wind sand and various impurities in the air, and the performance of the direct air-cooled heat exchanger has been reduced year by year. The ambient temperature is high all year round in summer, which has a bad effect on the back pressure of the unit. The location of the plant is very special. The peaks on both sides of the air-cooled island form a channel, and the air flow from the SSW wind direction flows through the inlet of the channel. The air-cooled island of the direct-cooling system is located in the middle of the channel, and the "narrow pipe effect" is formed on both sides of the channel. Increasing the environmental wind speed, but the specific impact value has not been studied. Therefore, the direct air-cooled island and the peaks on both sides of the plant are modeled, and the change of the direct air-cooling heat transfer capacity and the flow field in the air-cooled island area are analyzed by numerical simulation. Aiming at the problem of the influence of ambient wind on the heat transfer performance of air-cooled island, combined with the influence ability of indirect air cooling against natural factors and the characteristics of small end difference of heat transfer of jet condenser, a new type of extraction cooling method is put forward in this paper. The cooling effect of this method is compared with that of the traditional spray method, and it is found that the cooling effect is more ideal. Finally, the conclusion of this paper is summarized and prospected.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621
[Abstract]:In order to alleviate the shortage of water resources in the northern region, direct air cooling system is widely used in the world, especially in the areas rich in coal and water shortage. However, the heat exchanger of direct air-cooling system is exposed for a long time, and the cooling medium is air, so the temperature and wind speed of the surrounding air have a direct effect on the heat transfer capacity and normal operation of the heat exchanger. The heat transfer performance of direct cooling system is very important to the economy of unit operation, and the fluctuation of back pressure is closely related to the operation safety of the unit, so it is very important to study the performance change of direct air cooling system affected by environmental factors. Based on the investigation of the topography of a factory, it is found that the direct air-cooled unit in this plant has formed a certain scale outside the tube under the influence of the annual wind sand and various impurities in the air, and the performance of the direct air-cooled heat exchanger has been reduced year by year. The ambient temperature is high all year round in summer, which has a bad effect on the back pressure of the unit. The location of the plant is very special. The peaks on both sides of the air-cooled island form a channel, and the air flow from the SSW wind direction flows through the inlet of the channel. The air-cooled island of the direct-cooling system is located in the middle of the channel, and the "narrow pipe effect" is formed on both sides of the channel. Increasing the environmental wind speed, but the specific impact value has not been studied. Therefore, the direct air-cooled island and the peaks on both sides of the plant are modeled, and the change of the direct air-cooling heat transfer capacity and the flow field in the air-cooled island area are analyzed by numerical simulation. Aiming at the problem of the influence of ambient wind on the heat transfer performance of air-cooled island, combined with the influence ability of indirect air cooling against natural factors and the characteristics of small end difference of heat transfer of jet condenser, a new type of extraction cooling method is put forward in this paper. The cooling effect of this method is compared with that of the traditional spray method, and it is found that the cooling effect is more ideal. Finally, the conclusion of this paper is summarized and prospected.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621
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