The bearing system lubrication principle and rotor axial force balance principle of the magnetic drive pump provide a relatively complete theoretical basis for the magnetic pump. Therefore, the pump can generally achieve stable, low noise, and complete leakage in the early stage of operation. Good state. However, as the running time advances, the defects of the bearing appear under the continuous action of the liquid and hydraulic force.
1) The automatic liquid joint cannot achieve absolute balance of the thrust that the rotor bears in the axial direction. This is because the two sides of the rotor subjected to hydraulic action are not completely symmetrical in structure. Therefore, in any state, the rotor will be subjected to a total thrust pointing in a certain direction, and the two parts of the thrust bearing in this direction are compressed and have relative sliding friction.
2) In some cases, the total axial force of the rotor increases or the commutation leads to an increase in the thrust bearing load:
①It is caused by the large fluctuation of pump operating conditions. In actual operation, if the operating parameters (inlet pressure, outlet pressure) fluctuate greatly, the hydraulic balance of the rotor of the magnetic pump will be destroyed, and the sliding bearing will bear large radial and axial forces;
②The process is caused by pump down. There are 2 circulating pumps in the process absorption tower, one is on and the other is ready. In the process, in order to verify whether the standby pump is in good condition and ensure that the standby pump can be activated at any time, the pump is usually reversed once every two weeks (ie, the standby pump is turned on and off in turn). The pressure of the medium has a short-term high-low change process, which causes the thrust to be reversed in a short time, and the thrust bearing bearing the thrust is collided at this time.
3) Due to these characteristics of the axial force during the actual operation of the magnetic pump, the thrust bearing is required not only to have good wear resistance, hardness, etc., but also to have high compressive strength, toughness, extrusion resistance, and mechanical impact resistance. . The compressive strength and toughness of hard graphite are poor, so it is easy to be damaged and broken when the magnetic pump is running, and the fragments are taken away by the medium liquid. Under the action of the eddy current of the liquid, the axial displacement of the rotor increases, and the radial The vibration is intensified, and the radial graphite bearing is damaged by the extrusion and impact of the shaft. At the same time, the internal parts of the magnetic pump such as the inner magnetic steel body, the bearing body and the impeller seal ring are damaged by friction with each other, the noise is increased, and the pump output force is reduced until it cannot run.
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