Analysis and Research on Working Environment and Use of Magnetic Coupling
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- Time of issue:2021-06-09
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(Summary description)In the application of the magnetic drive pump, there are faults such as rapid wear of the thrust bearing and large vibration of the magnetic drive pump. Based on the actual situation on the site, some of the structure is modified and the vibration situation is analyzed. Failure analysis of magnetic drive pump...
Analysis and Research on Working Environment and Use of Magnetic Coupling
(Summary description)In the application of the magnetic drive pump, there are faults such as rapid wear of the thrust bearing and large vibration of the magnetic drive pump. Based on the actual situation on the site, some of the structure is modified and the vibration situation is analyzed. Failure analysis of magnetic drive pump...
- Categories:Industry information
- Author:
- Origin:
- Time of issue:2021-06-09
- Views:
Failure analysis and treatment of magnetic drive pump
In the application of the magnetic drive pump, there are faults such as rapid wear of the thrust bearing and large vibration of the magnetic drive pump. Based on the actual situation on the site, some of the structure is modified and the vibration situation is analyzed. Failure analysis of magnetic drive pump.
In 1940, the British used magnetic drive pumps for the first time to solve the leakage problem of chemical pumps with dangerous media. In recent years, magnetic transmission technology has developed rapidly, and has been gradually applied in the fields of petroleum, chemical industry, metallurgy, pharmacy, printing and dyeing, electroplating, food and environmental protection. Magnetic drive centrifugal pumps (referred to as magnetic pumps) have many failures, which affect their application and promotion to a certain extent. For example, magnetic materials are prone to loss of magnetism, resulting in the inability to transmit torque normally, and the limitations of media and pressure cannot adapt to process requirements.
Features of Magnetic Drive Pump
Magnetic drive pump is a new type of pump that uses permanent magnet magnetic drive to achieve non-contact torque transmission. When the motor drives the outer magnetic rotor (ie outer magnetic steel) assembly to rotate, through the action of the magnetic field, the magnetic field lines pass through the isolation sleeve to drive the inner rotor (ie inner magnetic steel) assembly and the impeller to rotate synchronously, because the medium is enclosed in a static isolation Inside the sleeve, so as to achieve the purpose of pumping the medium without leakage. The design ensures full sealing, no leakage, and no pollution, which can completely solve the problem of shaft seal leakage of mechanical transmission pumps.
1. Advantages The mechanical seal of the pump is cancelled, and the inevitable running, taking, drip and leakage of the centrifugal pump mechanical seal is completely eliminated, which is a good choice to achieve zero leakage and no pollution, and can realize the essential safety of the equipment. The overcurrent parts of the pump are made of stainless steel and engineering plastics, which can achieve corrosion resistance. The magnetic coupling is combined with the pump body and has the characteristics of compact structure and magnetic coupling can play an overload protection effect on the transmission motor. Less consumables, easy to repair, extended service life.
2. Disadvantages The transmission efficiency is low, compared with the centrifugal pump, the energy consumption is greater under the same process conditions. Now the domestic use of ferrite boron (NdFeB) and other permanent magnet material performance is not stable, process selection has certain limitations. In general, the process requires the media rating temperature, pressure and magnetic pump body material related. When the pump body is made of metal or F46 lining, the operating medium is rated at ≤ 80 degrees C and the rated pressure ≤ 1.6MPa. When the pump body is non-metallic, the rated temperature of the working medium ≤ 60 degrees C and the rated pressure ≤ 0.6MPa. When the rated temperature of the working medium ≥ 350 degrees C, the magnetic pump is in danger of demagnetic, it is difficult to achieve long-cycle safe operation, it needs to be designed separately. Suitable for transport media density ≤ 1300 kg/m, viscosity ≤ 30× 10-6m/s of ferromagnetic and fiber-free liquid. For high density, high viscosity of the medium, because the torque of the transmission is relatively large, there is no good application. Bearings are generally lubricated and cooled by the medium being transported, so the magnetic pump is strictly prohibited from empty load and reverse operation. The failure of magnetic materials, the failure caused in the actual operation, to solve the difficulties.
Failure analysis and treatment measures
1. Rapid wear of magnetic pump thrust bearing
(1) Cause analysis Blow out benzene raw material pump, model 50CQ-40 magnetic pump, flow 220L/min, head 40m, configuration motor power 4kW/table. After the pump has been running for a period of time, the rear bearings are severely worn, the rear thrust bearings are broken, and the impeller blades and the front cover of the pump body and the pump body components are worn. The direction of wear of impeller and thrust bearing is consistent, both of which show that the impeller sprang towards the inlet end, and the axial imbalance is obvious. The original impeller balance hole is enlarged and has no effect after assembly. Again, the front end thrust bearing wear depth of about 2 to 3mm, the thrust bearing material changed to 1Cr13, still does not solve the problem. Comprehensive analysis suggests that when the pressure difference between the bearings and the thrust disk on both sides of the pump is small, the flow rate of media lubrication is slow, or even can not flow, so that the heat generated by friction between each other is not easy to take away, resulting in the media vaporization intensified, resulting in dry grinding, resulting in thrust bearing failure. Therefore, the wear of the thrust bearing is the main cause of the rapid wear of the thrust bearing of the magnetic pump.
(2) Treatment measures to increase the lubrication of support bearings and thrust bearings. 50CQ-40 magnetic pump using axial force automatic balance device, but if the front-end bearings and thrust bearing lubrication is not good, then self-flushing cooling effect is not good, benzene media vaporized dry friction, will inevitably lead to bearings and thrust bearings quick wear. It has been calculated that the loss of resistance along the flow of the medium and the pressure distribution, the pressure difference between the front end thrust bearing and the support bearing < 0.1MPa, therefore, increase the lubrication there, become the key to solve the problem. Increase the back leaf clearance of the impeller by 1mm in order to reduce the axial imbalance force. In the front and rear support graphite bearing mating surface, each adds 4 straight grooves, depth of about 3 to 4mm, width and end face groove width is equal, deepen the end face groove, in order to improve the media flow effect. Block the medium lubrication holes between the two support graphite bearings, forcing the cooling lubricant to pass through the bearing's inner wall, avoiding dry friction and improving the lubrication effect by forcing flow.
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