直接空冷系统风机群优化运行

发布时间：2018-04-16 05:40

本文选题：直接空冷系统 + 轴流风机群　；参考：《华北电力大学》2015年硕士论文

【摘要】：直接空冷系统节水效果明显,在富煤缺水地区应用十分广泛。轴流风机群的经济运行是直接空冷机组经济运行的重要环节,也是降低厂用电的一个重要途径,因而对风机群的运行进行优化具有重要意义。本文以典型2×600MW直接空冷机组为例,通过CFD数值模拟,研究了不同风向、不同风速下空冷岛流动传热特性和机组净功率随不同区域风机群转速的变化规律。研究结果表明,迎风面风机受环境风影响比较大。以额定风机转速79rad/s为基准,当提高迎风面风机转速时,风机入口平均温度增加,冷却空气流量变化不大,空冷岛的流动传热特性略微变差；而降低转速时除了迎风面空冷单元,相邻一排空冷单元冷却换热效果也变差,故即使风机功耗减少,电厂的经济性依然下降。环境风从空冷岛侧面吹来,在风速较小时提高两侧风机转速可使空冷岛的流动传热特性有所改善,电厂净功率小幅增加,而环境风速比较大时电厂净功率减少。当提高迎风面以外其余风机转速至86.9rad/s时,冷却空气流量增加,空冷岛的冷却换热效果变好,电厂净功率变大,这说明电厂的经济性得到了提高；环境风速越大,净功率增加量越小,当风速达到15m/s左右时,空冷岛换热效果变差,电厂经济性降低。本文研究发现,环境风速不大时可以通过提高迎风面风机之外的其余风机转速来改善空冷岛的流动传热特性,进而提高直接空冷机组的经济性。
[Abstract]:Direct air cooling system has obvious water-saving effect and is widely used in areas rich in coal and water shortage.The economic operation of axial-flow fan group is an important link of direct air-cooled unit's economic operation, and also an important way to reduce the auxiliary power consumption, so it is of great significance to optimize the operation of fan group.Taking a typical 2 脳 600MW direct air-cooled unit as an example, the flow heat transfer characteristics of air-cooled island and the variation of unit net power with different regional fan group speed under different wind direction and different wind speed are studied by CFD numerical simulation.The results show that the upwind fan is greatly affected by the environmental wind.On the basis of rated fan speed 79rad/s, when the speed of upwind fan is increased, the inlet average temperature of fan increases, the cooling air flow rate changes little, and the flow heat transfer characteristic of air-cooled island becomes worse slightly, but when the speed is reduced, the air cooling unit is only upwind surface air cooling unit.The cooling and heat transfer effect of the adjacent air cooling unit also becomes worse, so even if the fan power consumption is reduced, the economy of the power plant is still decreased.When the ambient wind blows from the side of the air-cooled island, when the wind speed is small, the flow heat transfer characteristics of the air-cooled island can be improved, the net power of the power plant will increase slightly, and the net power of the power plant will decrease when the wind speed is relatively large.When the rotating speed of the other fans outside the upwind surface is increased to 86.9rad/s, the cooling air flow rate increases, the cooling heat transfer effect of the air-cooled island becomes better, and the net power of the power plant becomes larger, which indicates that the economy of the power plant has been improved and the environmental wind speed is higher.The smaller the net power increase is, when the wind speed reaches 15m/s, the heat transfer effect of air-cooled island becomes worse and the economy of power plant decreases.In this paper, it is found that when the ambient wind speed is small, the flow heat transfer characteristics of the air-cooled island can be improved by increasing the rotating speed of the fan other than the upwind fan, and thus the economy of the direct air-cooled unit can be improved.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM621

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