Drag reduction and energy saving method and application for gas drainage water ring vacuum pump

Water ring vacuum (WRV) pump is the main power equipment for the safe transportation of flammable and explosive gases such as methane, and its performance has a significant impact on the effectiveness of coal mine gas drainage. In the view of the problems that the WRV pump is a high-energy consumption and low efficiency rotodynamic machine, based on the working principle and the energy loss process of the WRV pump, a new energy saving method for WRV pump is proposed. The influence mechanism of the viscoelastic property of the polymer drag-reducing fluid on the gas-liquid two-phase flow field in the pump is presented. The WRV pump performance tests are conducted to investigate the influence of drag reducer type, concentration and pump speed on the energy-saving performance, and a polymeric drag reducer suitable for high turbulence and strong shear environment in WRV pump is developed. A set of energy-efficiency system of WRV pump is proposed to adapt to the working conditions for the coal mine gas drainage station, and the functions and technical processes of key units such as the preparation and replenishment device of drag-reducing fluid, quantitative water supply device and energy-saving operation and monitoring system for WRV pump are introduced. The results show that with the increase of the concentration of drag reducing fluid, the energy-saving rate and gas flow rate increase, and the optimal energy saving concentration is found to be 4.5 g/L. With the increase of inlet pressure, the energy-saving rate increases rapidly as a quadratic function, but the increase rate of gas flow rate decreases. When the pump speed increases, the energy saving effect become more obvious. The results of the field application in the Zhangji coal mine show that the technology can significantly reduce the energy consumption of the WRV pump operation. Under the condition of the constant drainage negative pressure, the energy-saving rate of the pump is 21.1%, and the net energy-saving rate from the cost-benefit analysis is 18.2%, which has a significant energy-saving benefit and effectively alleviates the problem of high-energy consumption of gas drainage pumping station.