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Mechanical Seal of Slurry Pump

Oct. 14, 2020

In the pumped medium of the slurry pump Expeller, the solid particles are large. When the medium flows through the pump equipment, it will cause certain corrosion and wear on the surface of the pump parts and sealing parts. The combined effect of corrosion and wear destroys the geometry of the parts and exacerbates the early failure of the equipment. Almost all the shaft seals of horizontal slurry pumps use mechanical seals. Therefore, mechanical seals have become a key component in horizontal slurry pumps.

First of all, the structural design of the mechanical seal must meet the overall design requirements of the pump, that is, to ensure that the slurry at the pump shaft is sealed reliably and without leakage during the operation of the pump. Considering the axial adjustment requirements of the rotor of the pump equipment, the mechanical seal should allow the axial adjustment of the rotor.

Secondly, due to the pressure of the pump cavity and the temperature of the medium, the mechanical seal should form a liquid film of sufficient thickness between the end faces of the friction pair, which can resist the pressure of the pump cavity, but also lubricate and cool the end face of the friction pair to effectively prevent the friction pair. Dry friction occurs.

slurry pump Expeller

Slurry Pump Expeller

Third, because the medium delivered by the pump contains a large number of solid particles and has a certain concentration, in the peripheral pump cavity of the mechanical seal part, affected by the disturbance of the impeller blades, the pressure and flow velocity of the medium in the cavity are prone to turbulence. phenomenon. The structural design of the mechanical seal should effectively prevent the precipitation of the slurry around the mechanical seal, damage and prevent the formation of friction pairs, which also puts forward requirements for the structural design of the pump chamber.
Fourth, the structural parts of the mechanical seal, such as the seat body of the moving ring and the fine ring, the rubber parts such as the O-ring seal, and the material of the friction pair, should have the same wear-resistant and corrosion-resistant requirements as the flow parts of the pump.

Fifth, affected by pump start and equipment shutdown, before a stable liquid film is formed between the friction pairs or at the moment when the stable liquid film is broken, a small amount of slurry will pass through the end face of the friction pair and enter the mechanical seal friction pair and shaft. Between sets. If these slurries are not removed in time, they will accumulate at the root of the friction pair, and even enter the spring seat. The accumulation of excess slurries affects the elasticity of the spring and then affects the specific pressure of the friction pair. Therefore, the mechanical seal should be designed with a reasonable flushing device to remove this part of the slurry in time.

Sixth, since the slurry delivered by the pump has a certain temperature, at the same time, the frictional heat is generated by the relative friction between the dynamic and static rings of the end face of the friction pair. If the temperature of the friction pair is too high, it will accelerate the aging of the surrounding sealant. A reasonable amount of flushing water should be calculated and determined.

Seventh, in addition to meeting the static pressure requirements, mechanical seals must also meet the requirements of sufficient manufacturing accuracy and have sufficient operating accuracy and a certain degree of operating reliability.

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