大型间接空冷塔优化设计研究

发布时间：2019-05-01 06:53

【摘要】：间接空冷系统设计的优劣直接关系到火电厂的安全运行和经济效益,因此对其进行塔型优化研究是十分必要的。借助Fluent数值模拟软件,以某600MW间接空冷机组为例,模拟研究了环境风对间接空冷塔内的空气流场产生的影响。结果表明,无风情况下,塔内空气流场呈现出均匀对称性。当环境风存在时,塔内空气流动发生偏斜,风速达到一定程度时,部分空气不能从空冷塔出口流出,发生“倒灌”现象,同时,在环境风的作用下,部分空气会从空冷塔底部的一侧散热器流入,从另一侧散热器流出,而未从空冷塔的出口流出,形成穿膛风。环境风速越高,“倒灌”现象和穿膛风现象越严重,这对机组的安全性和经济性产生了十分恶劣的影响。根据间接空冷系统热力特性和阻力特性的数学模型,对间接空冷塔的塔型进行了优化研究,应用VC++软件,开发了间接空冷塔塔型优化研究程序,用实例进行了分析和研究。分析发现,空气总流量L越大,空气出塔速度va2越小,容易发生“倒灌”现象；冷却水出塔温度tw2随空气总流量L、循环冷却水总量G的增加而降低,对应的凝汽器背压Pc越小,机组性能越好；空冷塔有效高度He越大,空冷塔抽力△PH越大,空气出塔速度va2越大,空冷塔的稳定性越好。由于空冷散热器和冷却水循环泵等供水设备的投资运行费用较高,实际应用中,建议选取空气总流量L较大、循环冷却水总量G较小、冷却三角个数n较小、空冷塔有效高度He较大的塔型。本文可结合经济性分析,求得技术上最合理,经济效果最好的塔型组合,具有很高的实用价值。
[Abstract]:The design of indirect air-cooling system is directly related to the safe operation and economic benefit of the thermal power plant, so it is very necessary to study the optimization of the tower form of the indirect air-cooling system. With the help of Fluent numerical simulation software, the influence of ambient wind on the air flow field in an indirect air cooling tower was studied by taking a 600MW indirect air cooling unit as an example. The results show that the air flow field in the tower shows uniform symmetry when there is no wind. When the environmental wind exists, the air flow in the tower is skewed, and when the wind speed reaches a certain extent, part of the air cannot flow out from the outlet of the air cooling tower, resulting in the phenomenon of "reverse irrigation". At the same time, under the action of the environmental wind, Some air will flow in from one side of the bottom of the air cooling tower, from the other side of the radiator, and not from the outlet of the air cooling tower, forming the perforating air. The higher the environmental wind speed, the more serious the phenomenon of "reverse irrigation" and "rifling wind", which has a very bad effect on the safety and economy of the unit. According to the mathematical model of thermal and resistance characteristics of indirect air-cooling system, the optimization of tower type of indirect air-cooling tower is studied. Using VC software, a program for optimization of indirect air-cooled tower type is developed, and an example is given to analyze and study the optimization program of indirect air-cooling tower type. It is found that the larger the total air flow L, the smaller the velocity va2 of the air out of the tower, which is prone to the phenomenon of "reverse irrigation". The cooling water outlet temperature (tw2) decreases with the increase of total air flow rate (L) and total circulating cooling water (G). The smaller the relative condenser backpressure (Pc), the better the unit performance. The greater the effective height He of the air cooling tower is, the greater the suction PH of the air cooling tower is, the greater the air output speed va2 is, and the better the stability of the air cooling tower is. Because of the high investment cost of water supply equipment such as air cooling radiator and cooling water circulating pump, it is suggested that the total air flow rate L is larger, the total circulation cooling water G is smaller, and the number of cooling triangles n is smaller than that of air cooling radiator and cooling water circulating pump. The effective height of air cooling tower is larger than that of He. Combined with the economic analysis, this paper can obtain the most reasonable technical and economic effect of the tower combination, which has a high practical value.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621

【参考文献】