Flushing and Lubricating Circuit of Magnetic pump

A.Design flow rate and influencing factors of flushing and lubricating pipeline of magnetic pump.

The flushing and cooling of the magnetic pump depends on its own medium to circulate the flushing lubrication. It introduces the high-pressure liquid flow from the back of the impeller into the isolation sleeve, and part of the liquid flow flows into the balance hole on the back of the impeller through the intermediate bearing. Part of the liquid flow flows through the gap between the isolation cover and the internal magnetic rotor, and then flows into the pump impeller entrance through the central hole after passing through the bearing in the isolation sleeve.

The flow rate of the flushing lubrication loop is usually 2%-3% of the designed flow rate of the pump. If the flushing cooling is not sufficient, the annular area between the inner magnetic rotor and the isolation sleeve produces high heat due to eddy current. At the same time, the increase of the medium temperature will further aggravate the vaporization of the medium. because the flushing cooling system of the magnetic pump does not have a suitable exhaust system, the gas in the pipeline will further reduce the flushing cooling effect, thus forming a vicious circle. eventually, the temperature of the medium will be higher than the allowable temperature of the permanent magnet, resulting in the gradual loss of magnetism of the internal and external magnet, resulting in the failure of the magnetic actuator. Sometimes it also causes sliding bearings to break up due to uneven heating.



B.Clearance control of sliding bearing and shape of guide groove.

Bearing clearance is an important technical parameter of sliding bearing. If the clearance is too small, the friction power of the pump increases during operation, which affects the pump efficiency, and serious failures such as thermal expansion and hugging of the shaft will occur. If the choice of clearance value is too large, it will accelerate the wear of the bearing, and in serious cases, the vibration will increase, affecting the normal operation of the pump. Bearing clearance is generally selected when the bearing leaves the factory, but it is only assembled and checked on the spot.

The guide groove of the sliding bearing is the key link of the cooling circulation loop of the magnetic pump. The guide groove ensures the smooth flow of the working medium, removes the sundries in the air and lubricating medium, and plays the role of forced lubrication and cooling. There are two kinds of guide groove structure: ordinary guide groove and hydrostatic guide groove.


C.Small flow operation of magnetic pump.

The minimum flow rate of magnetic pump is a very important technical problem. When the actual flow rate of the pump is less than the designed minimum flow rate of the pump, the liquid temperature in the pump cavity will gradually increase, and the liquid temperature at the isolation sleeve of the magnetic pump will also rise sharply, resulting in the vaporization of the circulating liquid and the dry friction of the sliding bearing of the pump. resulting in sliding bearing damage, magnetic steel demagnetization and so on, but also cause the following problems:

1.cavitation vibration.

2.the decrease of the outlet pressure of the pump reduces the pressure difference between the inlet and outlet of the pump, which can not guarantee the normal flow rate of circulating cooling in the pump.

3. the pressure change in the pump cavity can not guarantee the axial force balance of the pump rotor or affect the operation of the axial force automatic balancing mechanism.