Tips and ways to improve the reliability of magnetic pumps

1. Foreword Our company’s new product 40,000 tons/year chloride equipment has been officially put into use. During the equipment selection period of the project, we conducted extensive research, adhered to the concept of innovation, and selected 27 new Hermetik magnetic pumps based on the principles of the production process and the characteristics of the medium to be transported. Himetik magnetic pumps are produced by Dalian Himetik Sealed Pump Co., Ltd. The pump has advanced design and no shaft seal. As a leak-free, maintenance-free and reliable centrifugal pump, it is safe, efficient and energy-saving. Suitable for transporting corrosive, toxic, flammable, explosive, expensive or easily vaporized liquids. In addition, Hermetic magnetic pumps are also suitable for transporting high-temperature and low-temperature fluids and liquids under vacuum. Because it has the advantage of being completely leak-free, it successfully solves the problems of running, popping, dripping and leaking in fluid transportation. It has become an irreplaceable product in environmental protection projects and is widely used in petroleum, chemical industry, refrigeration, air conditioning, aerospace, etc. in the field. ​

Compared with traditional sealed pumps, Hermetik magnetic pumps have the advantages of less maintenance and repair work, no need for external lubricating oil, no leakage, and low vibration and noise. However, due to its own characteristics, it is different from traditional centrifugal pumps in many aspects, so some measures and approaches must be taken in terms of technology, installation, operation, etc. to ensure its reliable and smooth operation.
2. Characteristics of Hymetik magnetic pump

1. Structure: The Hermetic magnetic pump is a horizontal, completely leak-free centrifugal pump with axial suction and radial discharge. mask machine parts cam bevel shaft and gear is driven by a magnetic coupling and has no rotating shaft seal device. The Hermetic magnetic pump achieves “zero leakage” “. ​

2. Bearings: The drive shaft of the Hermetic magnetic pump is supported by rolling bearings, which are lubricated by its own grease; the pump shaft is supported by hydraulic sliding bearings. ​

3． Magnetic coupling: The magnetic block of the Haimetike magnetic pump is made of high-quality rare earth permanent magnet material. Its maximum irreversible temperature can reach 350-400°C, which fully ensures the reliable performance of the magnetic coupling. During normal operation, the magnetic coupling operates synchronously with the three-phase asynchronous motor and has stable performance. Moreover, the permanent magnets are highly stable and prevent adverse effects when assembling and disassembling the rotor or when the pump is operating at maximum transmission torque. ​

4． Lubrication of sliding bearings and cooling of magnetic couplings: lubrication and cooling by the medium delivered by the pump, without the need for external lubricating oil and cooling water systems. ​

5. Axial force balance: During operation, the axial force of the Hermetic magnetic pump is automatically balanced by hydraulic power, and cold rolled plate cnc equipment shield only bears instantaneous axial thrust during startup and stop. ​

3. Analysis of common faults of Hymetik magnetic pumps

1. Problems caused by large fluctuations in pump operating conditions: The axial force of the Hermetic magnetic pump is automatically balanced through hydraulic equalization. In actual operation, if the operating parameters (inlet pressure, outlet pressure) fluctuate greatly, it is easy to destroy the hydraulic balance of the Hermetic magnetic pump, causing the sliding bearing to bear large radial and axial forces, resulting in bearing damage. ​

2. Pump problems caused by cavitation: The main reasons for pump cavitation include large pipe resistance at the pump inlet, more gas phase in the conveying medium, insufficient pump filling, and insufficient energy head at the pump inlet. Cavitation is the most harmful to the pump. When cavitation occurs, the pump vibrates violently and the hydraulic balance is seriously damaged, which will cause damage to the pump bearings, rotor or impeller. This is a common reason for the failure of Hermetik magnetic pumps.

3. There is no medium or the flow rate of the conveyed medium is small: the bearings will dryly rub and burn the bearings. The Hermetic magnetic pump uses the conveying medium to provide lubrication and cooling to the sliding bearing. If there is no inlet valve or outlet valve, the sliding bearing will be damaged due to the lack of lubrication and cooling of the conveying medium. ​

4. Damage to the isolation sleeve: The magnetic coupling of the Hermetic magnetic pump is cooled by the medium delivered by the pump. If there are hard particles in the medium, it is easy to cause the isolation sleeve to be scratched or punctured. Sometimes it is also possible if the maintenance method is improper. causing damage to the isolation sleeve.

3. Methods and approaches to improve the operational reliability of Hermetik magnetic pumps

1. Equipment and pipeline installation requirements:

(1) The inlet and outlet pipelines of the pump should be supported to prevent additional loads from being transmitted to the pump. The pump cannot be used as a stress point in the pipeline. It is necessary to ensure that the pipeline system has compensation measures for thermal expansion. ​

(2) When the positive suction pressure head is low, the inlet pipeline should be as short as possible to prevent cavitation. The inlet pipeline should be of appropriate size to ensure that the fluid flow rate does not exceed 3m/s; when transporting easily vaporized fluids or liquefied gases, ensure that the flow rate does not exceed 3m/s; when transporting easily vaporized fluids or liquefied gases, ensure that the flow rate No more than 1m/s. (3) A regulating valve should be installed on the outlet pipeline to adjust the flow and lift of the pump. When using long outlet lines or when two pumps are used in parallel, it is recommended to install an additional one-way check valve. ​

(4) The entire piping system and auxiliary piping should be carefully cleaned to prevent iron filings, welding slag or other foreign matter from entering the Hermetik magnetic pump. For new piping systems, the inlet piping should be equipped with a filter. ​

(5) The pipeline design should take the exhaust of the pump into consideration. ​

(6) In order to achieve continuous operation of the pump, it is recommended to install a return pipeline and install a minimum flow orifice plate to ensure sufficient lubrication and cooling of the sliding bearing during continuous operation. As shown in Figure 1, the return pipeline should be led from before the outlet valve or one-way check valve, and return to the liquid storage tank through the minimum flow orifice plate. This installation enables automatic venting of the pump. (7) Hermetic magnetic pump must work within the specified range. To control maximum flow, it is recommended to install a suitable maximum flow orifice plate on the outlet pipe. (As shown in Figure 1)

2. Process monitoring: Due to the design characteristics of Hermetik magnetic pumps, maintenance is generally not required. However, in order to ensure its normal operation and safe operation, process monitoring devices should be used and strictly managed. ​

(1) The liquid level protection control of the inlet tank is necessary. The inlet tank should be equipped with a liquid level transmitter or a liquid level switch. When the liquid level in the inlet tank drops to a certain level, the operation of the pump will be automatically stopped to protect the pump. ​

(2) The pump body should be equipped with a temperature sensor to monitor the temperature of the magnetic stator and pump bearings and protect the bearings and magnetic stator. ​

(3) The pump outlet should be equipped with a liquid level regulating valve to adjust the displacement of the conveyed medium according to the liquid level of the inlet tank. ​

(4) A differential pressure sensor and switch should be installed to measure the differential pressure between the pump outlet and inlet. When the differential pressure is lower than the set value, the pump will be automatically stopped to protect the pump. ​

(5) The vibration of the pump is extremely small. Larger vibration and noise indicate failure. (6) In order to ensure normal operation, the pump should be ensured to work within the flow and lift range shown in Figure 2. The minimum and maximum working flow and lift are stated on the performance curve. ​

(7) In order to avoid cavitation, the Hermetic magnetic pump requires a minimum suction head (emin) when transporting easily vaporized fluids, which is calculated by the following formula: (emin) (m) = NPSH pump (m) + inlet pipe Friction loss (m) + safety margin (m), the safety margin is usually 0.5m. ​

3. Operation points:

(1) Filling and exhausting: In order for the Hermetic magnetic pump to operate normally, it must be fully filled and exhausted. By fully opening the valves in the pump inlet pipeline, return pipeline, and outlet pipeline, the automatic exhaust of the Mitic magnetic pump can be realized. When transporting liquefied gas or easily vaporized liquid, exhaust must be repeated several times until the pump is filled with liquid. If transporting low-temperature liquid, wait until the flow-passing parts of the pump are cooled to the temperature of the liquid before starting. This ensures that the fluid has reached all parts of the pump. ​

(2) Start-up procedure The model of the magnetic coupling is selected according to the driving motor to achieve normal operation, but it is started under uncomfortable conditions (such as excessive motor power, excessive opening of the outlet valve or high voltage, etc.) , will exceed the maximum torque of the magnetic coupling and prevent the pump from operating normally, so be sure to start it correctly. a. Completely open the valve in the inlet pipeline; b. Close the valve in the outlet pipeline; c. Start the motor; d. Slowly open the valve in the outlet pipeline; e. Adjust the outlet valve until normal working pressure is reached; f. In order to use For the normal operation of the pump, the pump should be allowed to work within its permitted range.
4. Operation and maintenance precautions:

1. Hermetik magnetic pumps are absolutely not allowed to work in a dry friction state or when the outlet pipeline valve is closed, otherwise the sliding bearing will be damaged! ​

2. It must work synchronously with the motor. If the pump fails (the head is very small), it indicates that the maximum torque of the magnetic coupling has been exceeded, and long-term work under inappropriate working conditions should be avoided. ​

3． Under normal working conditions, vibration, loud noise and power increase indicate that the bearing is worn (insufficient lubrication) and should be checked immediately. ​

4. The rolling bearings of Hermetik magnetic pumps are deep groove ball bearings, which rely on their own grease for permanent lubrication, but are also regularly inspected and replaced. ​

5． Failure of the magnetic coupling does not mean damage to the permanent magnet. However, working in a failed state for a long time will cause damage to the sliding bearing due to its low speed and poor lubrication of the sliding bearing. ​

6. The rotor assembly and drive assembly have high magnetism. When assembling and disassembling the Mitic magnetic pump, the magnetic range should be considered. It may have a certain impact on electric and electronic devices. Be careful to keep a certain distance! ​

7． If the transported liquid will crystallize or solidify when left for a long time, the pump should be flushed with a suitable liquid.