Magnetic pump by the pump, magnetic actuator, the motor consists of three parts. The key components of the magnetic actuator consists of an outer magnetic rotor, an inner magnetic rotor and a non-magnetic isolation cover. When the motor drives the outer magnet rotor to rotate, the magnetic field can penetrate the air gap and the non-magnetic substance to drive the inner magnet rotor connected with the impeller to rotate synchronously to realize the powerless contact transmission and transform the dynamic seal into the static seal. As the pump shaft, the inner rotor is completely closed by the pump body and the isolation sleeve, thus completely solving the problems of running, running, dripping and leakage, and eliminating the leakage of flammable, explosive, toxic and harmful media through the pump seal in the refining and chemical industry Of the security risks, effectively guarantee the physical and mental health and safety of workers. First, the working principle of the magnetic pump The n pairs of magnets (n is even) according to the law arranged in the magnetic clutch inside and outside the rotor, so that the magnet part of each other to form a complete coupling of the magnetic system. When the inner and outer two poles are in opposite polarities, that is, the displacement angle between the two poles is Φ = 0, the magnetic energy of the magnetic system is the lowest. When the poles rotate to the same poles, that is, the displacement angle Φ = 2π / n, the magnetic system at this time the maximum magnetic energy. After removing the external force, due to the mutual exclusion of the magnetic poles of the magnetic system, the magnetic force will restore the magnet to the state with the lowest magnetic energy. So the magnet produces the movement, drives the magnetism rotor to rotate. Second, the structural characteristics 1. Permanent magnets Permanent magnet made of rare earth permanent magnet has a wide range of operating temperature (-45-400 ℃), high coercive force and good anisotropy in the direction of magnetic field, and will not demagnetize when the same pole is close Phenomenon, is a good source of magnetic field. 2. Isolation Sleeve When using a metal isolating sleeve, the isolating sleeve is in a sinusoidal alternating magnetic field that induces eddy currents and converts it into heat in a cross-section perpendicular to the direction of the magnetic flux. The eddy current is expressed as:. Of which Pe-eddy current; K-constant; n-pump rated speed; T-magnetic torque; F-pressure within the spacer; D- inner diameter of the spacer; a material resistivity; When the pump is designed, n, T is given conditions, to reduce the eddy current only from F, D, and so on. Selection of high resistivity, high strength non-metallic materials made isolation sleeve, the effect of reducing eddy current is very obvious. 3. Cooling lubricant flow control pump operation, you must use a small amount of liquid on the inner rotor and the isolation sleeve between the annular region and the sliding friction bearing pair was washed and cooled. Coolant flow is typically 2% to 3% of the pump design flow, and the annulus area between the inner magnet rotor and the isolation sleeve generates high heat due to eddy currents. When the cooling fluid is not enough or flushing hole poor, blocked, it will lead to the medium temperature is higher than the permanent magnet operating temperature, the magnetic rotor gradually lost magnetism, the magnetic actuator failure. When the medium is water or water-based liquid, the annulus area can be maintained at 3-5 ℃. When the medium is hydrocarbon or oil, the annulus area can be maintained at 5-8 ℃. 4. Slide bearing magnetic pump sliding bearing materials impregnated graphite, filled with PTFE, engineering ceramics. As the engineering ceramics have good heat resistance, corrosion resistance, abrasion resistance, so the use of magnetic bearings multi-purpose sliding bearing made of engineering ceramics. As the engineering ceramics are very brittle and the expansion coefficient is small, so the bearing clearance must not be too small, in order to avoid the occurrence of axial accidents. As the magnetic pump sliding bearings to the lubrication of the media, it should be based on different media and the use of conditions, the use of different materials made of bearings. 5. Protection When the driven parts of the magnetic actuator operate under overload or the rotor is stuck, the main and driven parts of the magnetic actuator will automatically slide off to protect the pump. In this case, the permanent magnet on the magnetic actuator will generate eddy loss and magnetic loss under the action of the alternating magnetic field of the active rotor, causing the temperature of the permanent magnet to rise and the magnetic actuator to slip off. Third, the advantages of magnetic pump with mechanical seal or packing seal centrifugal pump compared to the magnetic pump has the following advantages. 1. Pump shaft seal from the dynamic seal into a static, completely avoiding media leakage. 2. No need for independent lubrication and cooling water, reducing energy consumption. 3. Driven by the coupling into a synchronous drag, there is no contact and friction. Low power consumption, high efficiency, damping and vibration damping effect, reducing the impact of motor vibration on the pump and pump cavitation vibration on the motor. 4. Overload, the relative rotation of the rotor inside and outside, on the motor, pump protection. Fourth, the operating precautions 1. Prevent particles from entering (1) Does not allow ferromagnetic impurities, particles into the magnetic clutch and bearing friction. (2) After conveying the easily crystallized or precipitated medium, it should be rinsed promptly (after the pump is stopped, pour water into the pump chamber and discharge clean after running 1min) to ensure the service life of the sliding bearing. (3) When transporting media containing solid particles, filter at the inlet of the pump tube. 2. Prevent demagnetization (1) Magnetic moment can not be designed too small. (2) It should be run under the specified temperature, the medium temperature is strictly not allowed. A platinum resistance temperature sensor can be installed on the outer surface of the magnetic pump isolation sleeve to detect the temperature rise in the annulus area so as to alarm or stop when the temperature exceeds the limit. 3. Prevent dry friction (1) Do not idle. (2) It is forbidden to use the medium to empty. (3) In the case of the outlet valve is closed, the pump continuous operation time shall not exceed 2min, to prevent the magnetic actuator from overheating failure.
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