canned motor pump principle structure characteristics
1, the principle of the canned motor pump is to use the same shaft of the motor rotor and plunger metering pump impeller fixed together, and then use the shield cover to shield this group of rotors.
The stator of the motor is surrounded by a shield, which is made of metal, so the power can be transmitted to the rotor by magnetic fields.
The entire rotor is being pumped through the fluid.
The end of the shield is sealed by a flange or welded structure.
The shield sleeve is actually a pressure vessel.
The inner surface of the stator and the outer surface of the rotor are provided with the stator canned sleeve and rotor canned sleeve made of corrosion-resistant metal sheet.
The respective ends are welded with corrosion-resistant metal sheets, separated from the liquid being transported, so that the stator winding core and rotor core are not corroded.
In addition to the shield sleeve, there is also a circulation tube, which USES the pumping liquid to lubricate and cool the bearings, and sometimes also to cool the motor.
Shielding pump axial force balance mode, usually use automatic thrust balance device, sometimes also choose impeller back with radial blade, that is back impeller thrust balance mechanism.
2, the advantages and disadvantages of canned motor pump advantages
(1) completely closed.
There is no movable seal on the structure, only static seal on the shell of the pump, so it can be completely leak-free, especially suitable for conveying flammable, explosive, valuable liquid and toxic, corrosive and radioactive liquid.
The rotor and stator each have a canned sleeve so that the rotor and stator of the motor do not contact with the material, even if the canned sleeve is broken, there is no risk of external leakage.
(3) compact structure and small footprint.
Pump and electrical system as a whole, disassembly need not find the center.
Low base and foundation requirements, and less routine maintenance workload, low maintenance costs.
(4) smooth operation, low noise, do not need to add lubricating oil.
Since there are no rolling bearings and motor fans, there is no need to add lubricating oil and low noise.
(5) wide range of use.
High temperature, high pressure, low temperature, high melting point and other conditions can meet the requirements.
canned pump disadvantages
(1) because the canned pump using sliding bearing, and with the medium to be lubricated, so the lubricity of the poor medium is not suitable to use the shield pump transport.
Generally suitable for canned pump medium viscosity is 0.1-20mpa ·s.
The efficiency of the canned pump is usually lower than the single-face mechanical seal centrifugal pump, and the double-face mechanical seal centrifugal pump is roughly equivalent.
For a long time in the small flow of the operation, canned pump efficiency is low, will lead to heat, liquid evaporation, and cause pump dry turn, thereby damaging the sliding bearing.