There are many reasons for the cavitation of boiler feed pumps, some of which are directly formed by one factor, and some are the result of multiple factors:
1 The user does not understand the performance parameters of the boiler feed pump or does not understand it at all, and improper installation and use;
2 The change of water diversion conditions makes the water level of the pumping station into the pool too low;
3 The boiler feed water pump is not matched with the power unit, the transmission device is not matched, and the speed is too high;
4 The design of the inlet pool is unreasonable, resulting in eddy currents and bias currents. The inlet pipe is too shallow to be immersed in the water;
5 The water inlet pipe is too long, the pipe diameter is too thin, the attachment is too much, the turning is too much, and the head loss is too large;
6 The boiler feed water pump inlet is blocked and the water flow is blocked;
7 The water content of the water source is too large;
8 boiler feed pump production process reasons, the inner surface of the impeller and pump casing is too rough, too much resistance to water flow.
According to the actual observation that the boiler feed water pump is overhauled and replaced by the impeller for several years, the cavitation wear of the boiler feed pump casing is mainly occurred in the week of the spiral pressure water chamber near the seal ring on both sides, and the arrangement direction is consistent with the water flow, and the dense depth is about 3 to 10 mm of cavitation holes, the surface loss of cast iron is 3 to 5 mm thick, gradually weakens outward, and gradually becomes a shallow shallow groove from a dense deep groove until the deepest part of the pump cavity is reduced to a fish scale pit. . In the vicinity of the casting structure cavity in the boiler feed water pump, especially close to the sealing ring, the groove which penetrates the high pressure chamber and the low pressure chamber is formed by the gap cavitation, and the depth is 3 to 5 mm and the width is 5 to 15 mm. Cavitation or even grooves appear in the pump body. The end of the tongue is gradually thinned and shortened. In severe cases, it is shortened by about 60 mm. The impeller mainly has many cavitation holes at the edge of the blade. The cover plates on both sides are obviously worn, the end of the impeller blade is broken, the diameter of the impeller becomes smaller, and the seal ring wears. The radial sealing surface of the impeller and the sealing ring appears in the circumferential deep groove.
