直接空冷系统凝结水下降管振动分析与治理

Analysis and treatment of vibration of condenser pipe in ACC

直接空冷系统普遍存在凝结水下降管振动问题,振动严重时危及空冷系统安全运行。基于流固耦合方法建立管道振动模型,采用流致振动和流体空化理论对凝结水管的两相流特性进行分析,对某超超临界660 MW机组凝结水管进行模型解析计算和数值模拟。结果表明:饱和或近饱和的凝结水从空冷平台沿凝结水下降管采用重力自流的方式流到排汽装置热井,在水的势能释放过程中,产生两相流激振和空化的现象,这是产生凝结水振动和空化噪声的原因;在电厂凝结水管道中采用多级文丘里管+多孔孔板的措施消除凝结水势能,并避免产生管道振动和噪声超标,消除了管道振动的隐患。

Condensate downcomer vibration is a common phenomenon in the direct air cooling system,which endangers the safe operation of the air cooling system when the vibration is serious.The pipe vibration model is established based on the fluid solid coupling method.The two-phase flow characteristics of the condensate pipe are analyzed using the theory of flow induced vibration and fluid cavitation.The model analytical calculation and numerical simulation are carried out for the condensate pipe of a 660 MW ultra supercritical unit.The results show that saturated or nearly saturated condensate flows from the air cooling platform along the condensate downcomer to the hot well of the steam exhaust device by gravity flow.When the potential energy of water is released,two-phase flow excitation and cavitation phenomena occur.Based on this analysis,the causes of condensate vibration and cavitation noise are found,By using multi-stage Venturi tubes and porous orifice plates in the condensation water pipeline of the power plant to eliminate the condensate potential energy,avoid excessive pipeline vibration and noise,and eliminate the hidden danger of pipeline vibration.