Magnetic pump is composed of pump, magnetic actuator and motor.
The magnetic actuator is composed of an external magnetic rotor, an internal magnetic rotor and a non-magnetic isolation sleeve.
When the motor drives the external magnetic rotor to rotate, the magnetic field can penetrate the air gap and non-magnetic substances, drive the internal magnetic rotor connected with the impeller to rotate synchronously, realize the non-contact transmission of power, and transform the dynamic seal into the static seal.
Because the pump shaft, internal magnetic rotor is completely closed by the pump body, isolation sleeve, thus thoroughly solve the “run, run, run, drop, leakage” problem, eliminate the oil refining and chemical industry inflammable, explosive, toxic, harmful media through the pump seal leakage of safety hazards, effectively ensure the physical and mental health and safe production of workers.
The n pairs of magnets (n is even) are arranged and assembled on the inner and outer magnetic rotors of the magnetic actuator in a regular manner, so that the magnetic parts can form a fully coupled magnetic system.
When inside and outside the two poles are relative, heteropolar displacement Angle between the two poles Φ = 0, the magnetic system of magnetic energy minimum;
When the magnetic rotation to homopolar relative, that is, between the two poles of displacement Angle Φ = 2 PI/n, the magnetic system of magnetic energy is the largest.
After removing the external force, the magnetic force will restore the magnet to the state with the lowest magnetic energy, because the magnetic poles of the magnetic system repel each other.
The magnet then moves, driving the magnetic rotor to rotate.
The permanent magnet made of rare earth permanent magnetic materials has a wide operating temperature range (-45-400℃), high coercive force, good anisotropy of the magnetic field direction, and no demagnetization occurs when the same pole is close to each other. It is a good source of magnetic field.
When the metal isolation sleeve is used, the isolation sleeve is in a sinusoidal alternating magnetic field, and the eddy current is induced and converted into heat on the section perpendicular to the magnetic field line.
The eddy current is expressed as:.
Pe- eddy current;
K – constant;
N – rated speed of the pump;
T- magnetic transmission torque;
F- pressure inside the spacer;
D- inner diameter of spacer sleeve;
The resistivity of a material;
— tensile strength of the material.
When the pump is designed well, n and T are given working conditions, and the reduction of eddy current can only be considered from the aspects of F, D, and, etc.
High resistivity, high strength of non – metallic materials used to make the isolation sleeve, in the aspect of reducing the eddy current is very obvious.
When the pump is running, a small amount of liquid must be used to flush and cool the annulus area between the inner magnetic rotor and the isolation sleeve and the friction pair of the sliding bearing.
The flow rate of coolant is usually 2%-3% of the designed flow rate of the pump.
When the cooling lubricant is not enough or the flushing hole is not free or blocked, the temperature of the medium will be higher than the working temperature of the permanent magnet, the internal magnetic rotor will gradually lose its magnetism, and the magnetic actuator will fail.
When the medium is water or water-based liquid, the temperature rise of the annulus region can be maintained at 3-5℃.
When the medium is hydrocarbon or oil, the temperature rise of the annulus region can be maintained at 5-8℃.
Magnetic pump sliding bearing materials are impregnated graphite, filled with ptfe, engineering ceramics.
Because engineering ceramics have very good heat resistance, corrosion resistance, friction resistance, so the magnetic pump sliding bearings are made of engineering ceramics.
Because the engineering ceramics are very fragile and the coefficient of expansion is small, so the bearing clearance must not be too small, in order to avoid shaft holding accident.
Because the sliding bearing of magnetic pump is lubricated with the medium conveyed, the bearing should be made of different materials according to different media and working conditions.
When the driven parts of the magnetic actuator run under overload or the rotor gets stuck, the main and driven parts of the magnetic actuator will slide off automatically to protect the pump.
The permanent magnet on the magnetic actuator
Related products: Stainless Steel Magnetic Pump | Diaphragm Pump
