Abstract:Abstract：Considering the fast start-up and vacuum deterioration of the unit can maintain the safe operation of the unit, the 600 MW thermal power unit has three vacuum pumps, and the design margin of the vacuum pump is large. In order to reduce auxiliary power consumption and power generation cost, this project puts forward the idea of retrofitting a single vacuum pump during the operation of the unit under the condition of better vacuum tightness. The modification method is to connect the high back pressure side with the low back pressure side vacuum pump inlet through the pipeline and install the adjustable electric valve on the connecting pipe so as to achieve the purpose of adjusting the pressure difference between the high and low back pressure condenser. The idea not only considers making full use of the original equipment and pipelines, but also guarantees the normal formation of high and low back pressure during the operation of the unit. Result of modification: When the vacuum tightness test results of unit condenser are less than 50 Pa/min, the average vacuum of one vacuum pump is the same as that of two vacuum pumps, which can keep a single vacuum pump running for a long time.