Retrofit of Cooling Water System of Water Ring Vacuum Pump in Power Plant

[Asia pump network] Water ring vacuum pump is a mechanical centrifugal pump, eccentric mounted in the cylindrical pump impeller rotor. When the impeller is rotated by the motor, the working fluid gets the peripheral velocity under the impelling of the blade. Due to the centrifugal force, it is thrown to the outer diameter to form a water ring swirling along the pump casing. Because of the eccentric arrangement of the impeller, Relative movement of the leaves, so that the space between the adjacent two leaves a cyclical volume changes, like a liquid piston radial reciprocating motion between the cascade, when the two blades of the "water piston" centrifugal push to go out, the space As the volume gradually increases from small to small, gas is drawn from the axial suction port. On the power plant water ring vacuum pump cooling water system transformation and when the blades between the "water piston" relative to the axial direction for relative movement, the space gradually from large to small, the inhalation of gas gradually compressed, discharged through the exhaust port. As the impeller rotates steadily, each volume changes in turns, allowing the suction and exhaust to continue, as shown. Water ring vacuum pump body structure IS body 2. Glue ball 3. Exhaust port 4. Inlet port 5. Impeller 6. Water ring Yangcheng power plant vacuum pump Tsurumi Vacuum (Shanghai) Co., Ltd. equipment. Vacuum pump model 150EVMA (imported, stainless steel impeller), the number of stages 2, the compression ratio of 1: 5, 1: 6. Water ring vacuum pump unit performance is as follows: Water ring vacuum pump suction pressure: minimum suction pressure Power: The maximum shaft power is 49kW, the minimum shaft power is 45kW at 11.8kPa. The power of 315M8, rated power is 75kW, speed is 740r / min, voltage is 380V, motor protection grade is IP44, motor insulation grade is F class. Pump heat exchanger: cooling water volume 25m3 / h, water quality is circulating water, water temperature is 2033C. (Two pumps running at the same time.) Heat exchanger: (Alfa Laval plate imported Alfa Laval products) heat transfer area of ​​7m2, cooling water pressure transformation增 r; increase k pieces of water and water vacuum system transformation diagram Third, the need for the transformation of the vacuum system In the operation of the power plant, the deterioration of the working conditions of the condenser will directly lead to the turbine consumption and unit output, when the unit steam consumption is not Variable, the deterioration of the vacuum 1%, will cause the steam turbine to reduce the power of about 0.7% of the rated capacity of 1%, when the unit load unchanged, equivalent to the power plant coal consumption increased by about 1% 2%. General power plant vacuum pump plate Type heat exchanger cooling water system uses industrial water, to the summer, industrial water cooling water temperature as high as 33C, resulting in reduced plate heat exchanger cooling effect, resulting in the water separator working temperature up to 42C, by the working principle of the vacuum pump and a certain Saturated temperature corresponds to a certain pressure, we can see that when the working water temperature reaches 42C, the vacuum pump ideal vacuum capacity of 93.1kPa, reducing the vacuum, seriously affecting the efficiency of the unit. Power plant steam turbine water ring vacuum pump size is based on power generation Yangcheng The design of the unit operating conditions selected OK, when the operation within the design range, the vacuum pump to normal operation, but in the summer cooling water temperature is high or dirty plate heat exchanger vacuum pump heat exchanger cooling effect is poor, The vacuum pump will operate under high vacuum, which is equivalent to running in a state of suffocation or suffocating. Due to the inherent physical phenomena, under certain water temperature conditions, the higher the vacuum, the higher the water temperature, the closer the water in the pump will boil and generate A large number of bubbles, bubble generation and rupture process will cause cavitation damage to the impeller, destroy the dynamic balance of the impeller Strong vibration caused by the pump body, vibrate the vacuum pump ancillary equipment (pressure vacuum gauge, pressure switch, inlet pneumatic door feedback device, etc.), and will emit very large cavitation noise, these conditions seriously affect the safe operation of the vacuum pump group And the safe operation of steam turbine generator.Based on the above analysis, to solve the unit vacuum to reduce and prevent cavitation damage to the vacuum pump equipment, the best solution is to reduce the working water four, the transformation process and the effect of the transformation process of transformation Yangcheng Power Plant According to the actual situation in the factory, taking into account the minimum investment case, the use of deep well water cooling water, and achieved good results for the vacuum system after the transformation of the factory deep well water pressure 0.4MPa, diameter 50mm, cooling water flow transformation After the effect and effectiveness of the use of deep well water cooling, first of all to solve the vacuum reduction in summer operation, affecting unit economy. The average deep well water temperature in summer is 18C, the working water temperature is 21C after deep well water cooling, the working water temperature inside the separator is 27C, and the ideal vacuum pumping capacity of the vacuum pump is 97.8kPa. According to the ideal condition, the condenser vacuum can increase 4.7 kPa, due to the actual operation, by the unit load, plate heat exchanger fouling, dirty, the average condenser vacuum increased 3.5kPa, the improvement rate of 3.45%. (Editor: Huang Nengwen QQ:)

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