Datang Wushan Power Plant due to a longer period of high load each year, so the steam turbine condenser water ring vacuum pump long-term operation in high vacuum conditions, especially the summer conditions even worse, the vacuum pump rotor blade material on the anti-cavitation Reach the limit, so that its service life is affected to some extent. After investigation, the installation of atmospheric ejector effectively avoids the influence of cavitation on the vacuum pump rotor and prolongs the service life of the vacuum pump. 1, a brief analysis of the causes of water ring vacuum pump cavitation Wushan power plant steam turbine water ring vacuum pump size is based on the design of the generator set operating conditions identified, when the operation within the design range , The vacuum pump can be normal operation, such as related reasons, such as: long-term operation of the unit at full capacity; summer cooling water temperature is too high or cooling water flow is too small, resulting in poor cooling effect of vacuum pump heat exchanger, vacuum pump will run under high vacuum, Close to or in a suffocating state of operation, due to the inherent physical phenomena, under certain water temperature conditions, the higher the vacuum, the water temperature is higher, the water in the pump is close to boiling and will produce a large number of bubbles, bubble generation and rupture will Cause cavitation damage to the impeller, destroy the dynamic balance of the impeller, cause strong vibration of the pump body, vibrate the ancillary equipment of vacuum pump (pressure vacuum gauge, pressure switch, feedback device of inlet pneumatic door, etc.), and will emit very large steam Noise erosion, these conditions have seriously affected the safe operation of the vacuum pump group and the safe operation of the turbine generator set. 2, the basis for technical transformation programs and detailed instructions If you want to solve the problem of cavitation of vacuum pumps, reduce the cost of water temperature larger, reducing the vacuum is so that the condenser back pressure rise is even more unlikely, which will seriously affect the load with the unit Capacity, the ideal approach is to solve the cavitation generated in the original water temperature, the system vacuum unchanged, the best option is to install the vacuum ejector to the vacuum pump, the whole vacuum pump group will be better extraction performance, so condensate Steam still can guarantee the current level of vacuum or higher, but the vacuum within the vacuum pump body only 12Kpa (this time the system vacuum within the 3-8Kpa range), which can effectively prevent cavitation. Atmospheric jet pump by: nozzle, suction chamber, and diffuser composition, the exhaust port and water ring pump inlet connected. Atmospheric ejector principle Introduction: First, start the water ring vacuum pump, the nozzle inlet and exhaust pressure difference between the formation of the atmosphere from the nozzle into the pump, when the pressure difference is the atmospheric pressure of 1/2, the air medium by The nozzle contraction section is accelerated to the larynx when the speed of sound can be reached, to expand the section can be further accelerated to the speed of sound, the diffuser to form a high-speed jet, and the resulting pressure in the suction chamber is lower than the pressure inside the container being evacuated, Inhaled into the room, due to the mixing of the two air-suction chambers, the loss of momentum exchange slows down the air flow rate and falls below the speed of sound as it enters the throat of the diffuser, further reducing the pressure through the diffuser expansion and increasing the pressure To achieve the discharge pressure of the air ejector, that is, the suction pressure of the water ring vacuum pump, the water ring vacuum pump sucked into the gas and then discharged from the pump, that is to complete the suction, exhaust process.
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