Function and Structure Analysis of Boiler Feedwater Pump in Power Plant

Boiler Feed Pumps, Condensate Pumps, Circulating Pumps are the three main types of pumps in power plants. The role of power plant boiler feed pump and structure analysis 1, the role of power plant boiler feed pump: 1) The role of feed pump is to deaerator tank has a certain temperature, in addition to oxygen feed water, after raising the pressure to the boiler to To meet the needs of boiler water. 2) The function of condensate pump is to send the condensed water in the hot well of the condenser to the regenerative system after being boosted. 3) The function of the circulating pump is to supply cooling water to the steam turbine condenser to condense the exhaust of the steam turbine. In power plants, circulating pumps also provide cooling water to oil coolers, water coolers, generator air coolers, and the like. 2, the role of feed pumps in the power plant Boiler feed pumps in power plants is to regulate and stabilize the water supply pressure and flow. The boiler and regenerative system need to overcome the system resistance in circulation, and the water pump also provides the impetus for the hydrodynamic cycle. In the entire unit, the outlet corresponds to the highest pressure, so the safe operation of the boiler feed pump can not be overlooked. The task of the water pump is to deaerator tank has a certain temperature, in addition to oxygen feed water, after raising the pressure to the boiler to meet the needs of the boiler water. Cavitation is the biggest safety hazard to the pump, if the deaerated water into the feed pump, the temperature will exceed the vaporization temperature of atmospheric water. When the feed pump inlet pressure is too low, the feed water vaporization occurs, and the resulting large number of bubbles, and when these bubbles into the high pressure zone, due to compression and rapid deformation and collapse, the occurrence of this phenomenon will block Runner, resulting in local shock pressure fluctuations. Huge dynamic impact pressure will cause sponge or honeycomb-like damage to metal materials due to fatigue erosion, causing cavitation in the pump body and causing pressure fluctuations in the feed water. In general, you can use additional front pump, through the inlet pressure to improve water supply to prevent cavitation. At the same time can also be combined with the pipeline characteristics, a reasonable choice of operating conditions point to ensure the safe operation of feed pumps. A feed pump characteristic curve shown in Figure 1, the pipeline characteristic curve can be Hq that a wide pipeline pump performance curve with Hv-qv said. The two curves intersect at M, and M represents the stable operating point of the pump. At intersection M, the head of the pipe system is equal to the head of the feed pump. Unit of quality of water through the pump to get the head of H energy, just the unit mass of water from the pump inlet cross-section to the pump outlet cross-section of the energy required, the energy supply and demand in the M point reached a balance. If the actual operating conditions at point A, the pump can only provide the energy of the HA head, and overcome the pipeline system will need Ha head energy, this time because of the lack of energy, causing the speed and flow are reduced, running The working point will also gradually move closer to point M and reach a new energy balance at point M. Similarly, when the actual operating conditions in the B, the need for head to overcome the pipeline resistance calendar, the pump can provide lift is greater than the water supply and flow rates are increased, the operating point is gradually close to the M point, the final balance at M. Accordingly, we can get M points for the stable operating conditions point. 3, power plant boiler feed pump structural features: DG power plant boiler feed pump is horizontal, single suction, multi-stage centrifugal pumps. Pump import and export are vertical upward. Tighten the pump suction section of the pump, the middle, the discharge section of the link into one, the pump rotor mounted on the shaft by the impeller, balance disc and other components. The entire rotor is supported by plain bearings at both ends of the shaft. Bearings lubricated with circulating cooling water. The axial force of the rotor is balanced by the balance disc. (Editor: Li Juan QQ:)

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