Protective Design of Water Hammer for Pumping Stations

Abstract

【Background and Objective】 Long-distance water conveyance is common in countries with uneven water distribution like China. Resolving water hammer is an issue faced in water-conveyance projects. The purpose of this paper is to investigate the feasibility of using air tank and air valve in water hammer protection in high-lift pumping stations. 【Method】 The study was based on a practical project. We first determined the conditions in the air tank nodes and the boundaries of the air valve. Base on the characteristic line method, a numerical model was then developed for the pump station, as well as the pipeline behind the pump, using the HysimCity software - a water hammer software for designing long-distance water conveyance projects. The model was used to simulate hydraulic transition process under different operating conditions, from which we compared and analyzed the effectiveness of the air tank and air valve in protecting water hammer when the pump was power off. The operating parameters of the air tank were optimized based on the numerical results. 【Result】 The air tank and air valve were effective in preventing water hammer. When the pump was powered off, water pressure in the regions proximal to the pump was always greater than zero, and the lowest water level in the air tank was higher than the elevation of the tank bottom. These met the design requirements that the water level in the tank bottom should be more than 1m deep, and the pressure in the pipelines between two adjacent pump stations should be more than -5 m and less than 200 m. 【Conclusion】 The air tank and the air valve can be used in a combination to protect pump stations from water hammer, and our results showed that they were effective and meet the design requirements.

Keywords

• water diversion project
• water hammer
• air tank
• air valve