停泵时泵后非瞬时降压的空气罐水锤防护方案

基于水泵停泵时的泵后非瞬时降压特性,给出了空气罐设置位置的选取原则和方法,结合工程算例,提出仅在管道中部设置空气罐防护方案和在管道中部开始串联设置空气罐防护方案,并通过数值模拟方法将这两种方案与常见的泵后设置空气罐防护方案进行水锤防护效果比较。结果表明,在防护效果相近的情况下,采用在管道中部开始串联设置空气罐的防护方案所需的空气罐容积最小,同时该方案下的罐内气体最大压力也相对较小,对空气罐的受力结构要求相对较低。在串联空气罐防护方案中,首端空气罐的主要作用是抑制管道压力降低,末端空气罐的主要作用是抑制管道压力升高。因此,在考虑串联空气罐的容积优化时,应结合输水系统水锤防护的实际需要,当输水管线的降压严重时,可考虑增大首端空气罐容积;当输水管线正压过大时,可考虑增大末端空气罐容积。

Water Hammer Protection Schemes of Air Vessel Based on Non-instantaneous Pressure Decrease under Pump-stopping Condition

Based on non-instantaneous pressure decrease of the pump under pump-stopping condition, the selection principles and methods of setting location of air vessel are given. Combined with an engineering example, two schemes that only set air vessel in the middle of the pipeline and set air vessels from the middle of the pipeline in series are proposed. And then the two schemes are compared with the scheme of setting the air vessel behind the pump by using numerical simulation methods. The results show that with the similar protection effects, the series scheme has the minimum volume, and the maximum air pressure in the air vessel of the scheme is relatively lower, which means that the stress structure is safer. In the series scheme, the main function of the first air vessel is inhibiting the pressure decrease of the pipeline, and the main function of the last air vessel is inhibiting the pressure rise of the pipeline. The volume optimization of air vessel should combined with the water hammer protection requirement of practical water-supply engineering, which increases the volume of the first air vessel when the pressure decrease of pipeline is severe as well as increases the volume of the last air vessel when the pressure of the pipeline is too high.