Expert Yogi
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| Magnetic pump is composed of pump, magnetic driver and motor. The key components of magnetic actuator are composed of external magnetic rotor, internal magnetic rotor and non-magnetic isolation sleeve. When the motor drives the outer magnetic rotor to rotate, the magnetic field can penetrate the air gap and non-magnetic substances, drive the inner magnetic rotor connected with the impeller to rotate synchronously, realize the non-contact transmission of power, and convert the dynamic seal into static seal. As the pump shaft and inner magnetic rotor are completely sealed by the pump body and isolation sleeve, the problem of "running, emitting, dripping and leaking" is completely solved, and the potential safety hazards of flammable, explosive, toxic and harmful media leaking through the pump seal in the oil refining and chemical industry are eliminated, effectively ensuring the physical and mental health of employees and safe production.
1? Working principle of magnetic pump
N pairs of magnets (n is an even number) are arranged and assembled on the inner and outer magnetic rotors of the magnetic driver according to the law, so that the magnet parts form a complete coupled magnetic system with each other. When the inner and outer magnetic poles are opposite, that is, the displacement angle between the two magnetic poles F= 0, at this time, the magnetic energy of the magnetic system is the lowest; When the magnetic poles rotate to opposite poles, that is, the displacement angle between the two magnetic poles F= 2 p /n, at this time, the magnetic energy of the magnetic system is the largest. After removing the external force, because the magnetic poles of the magnetic system repel each other, the magnetic force will restore the magnet to the state of minimum magnetic energy. Then the magnet moves and drives the magnetic rotor to rotate.
2? Structural features
1. Permanent magnet
The permanent magnet made of rare earth permanent magnet materials has a wide working temperature range (-45-400 ?), high coercivity, good anisotropy in the direction of the magnetic field, and will not demagnetize when it is close to the same pole. It is a good magnetic field source.
2. Isolation sleeve
When the metal isolation sleeve is used, the isolation sleeve is in a sinusoidal alternating magnetic field, which induces eddy current on the section perpendicular to the direction of the magnetic line of force and converts it into heat. The expression of eddy current is:. Where PE eddy current; K - constant; N - rated speed of pump; T-magnetic transmission torque; F-pressure in the spacer; D-inner diameter of spacer; I. resistivity of the material; -- Tensile strength of the material. When the pump is designed, N and T are given under working conditions. To reduce eddy current, we can only consider from the aspects of F, D, and. Selecting non-metallic materials with high resistivity and high strength to make isolation sleeves has a very obvious effect in reducing eddy current.
3. Control of cooling and lubricating fluid flow
When the pump is running, a small amount of liquid must be used to wash and cool the annulus area between the inner magnetic rotor and the isolation sleeve and the friction pair of the sliding bearing. The flow of coolant is usually 2%-3% of the design flow of the pump. The annulus area between the inner magnetic rotor and the isolation sleeve generates high heat due to eddy current. When the cooling and lubricating fluid is insufficient or the flushing hole is blocked, the medium temperature will be higher than the working temperature of the permanent magnet, causing the internal magnetic rotor to gradually lose magnetism and the magnetic driver to fail. When the medium is water or water-based liquid, the temperature rise in the annulus area can be maintained at 3-5 ?; When the medium is hydrocarbon or oil, the temperature rise in the annulus area can be maintained at 5-8 ?.
Vacuum pump system used in degradable resin PBAT industry |
Composition and working principle of magnetic pump
