Three types of seals for slurry pump shaft seals

Three types of seals for slurry pump shaft seals

For slurry pumps, we will refer to the pumps that are suitable for conveying suspended solids in liquids (mediums) as slurry pumps according to the particularity of the medium they transport. Mud pumps, impurity pumps, dredging pumps, sludge pumps, etc. are all within the scope of application of slurry pumps, and are currently one of the indispensable equipment in various process processes such as beneficiation, coal preparation, desulfurization, and filter press feeding. . For this reason, the sealing of slurry pumps is also constantly being valued. Choosing the correct sealing method can not only greatly improve the service life of the pump at the site, but also reduce economic losses.

The shaft seal of the slurry pump is divided into three types: packing seal, auxiliary impeller seal, and mechanical seal. Each of the three seal forms has advantages and disadvantages.

Packing seal

First of all, the packing seal is the most common kind of seal. The packing added in the stuffing box body is in full contact with the shaft and is filled with a certain amount of pressure water to prevent the transmission medium from leaking out. The pressure of the shaft seal water must exceed the outlet pressure of the slurry pump by 1.5 kg. When transporting corrosive materials, the filler may be corroded. So the disadvantage of this seal is that it cannot transport toxic and corrosive liquids. The packing shaft seal has a simple structure, convenient maintenance, and low price. This sealing method is widely used in ore dressing plants and coal washing plants.

Impeller seal

The secondary impeller seal of the slurry pump relies on the secondary impeller to generate a reverse centrifugal force to prevent the leakage of the slurry to achieve the sealing effect. The use of the secondary impeller seal requires the backpressure of the slurry pump to not exceed the outlet pressure of the slurry pump The single-stage pump or the first-stage pump of the multi-stage series pump can use the auxiliary impeller shaft seal. The auxiliary impeller shaft seal has the advantages of no shaft sealing water, no dilution of the slurry, and good sealing effect. Therefore, in cases where dilution is not allowed in the slurry, or when there is no flushing water at the user's operating site, such a seal can be considered.

Machinery Seal

The mechanical seal is that the moving ring and the static ring are closely contacted by the spring in the axial direction to achieve the sealing purpose. The mechanical seal is reliable and hardly leaks, but pay attention to protect the friction surface to avoid wear during installation. Mechanical seals are generally divided into single-end mechanical seals and double-end mechanical seals.

Commonly used single-end mechanical seals are divided into three types: no water injection mechanical seal, water injection external flushing mechanical seal, and water injection inner flushing mechanical seal. Non-water-filled mechanical seals do not require shaft seal water, also known as dry mechanical seals; water-filled external flushing mechanical seals require shaft seal water. The shaft seal water pressure is 1.5 kg, also known as external flushing mechanical seals; water-filled internal seals Washing mechanical seals requires shaft seal water. The pressure of the shaft seal water must exceed 1.5 kg of the outlet pressure of the horizontal slurry pumps. It is also called internal flushing mechanical seal. It is recommended to use undiluted slurry or dissolve with the slurry without affecting the characteristics of the slurry. The flushing liquid is used to flush the mechanical seal inward.

The double-face seal needs to be equipped with a flushing scheme to lubricate the second mechanical seal. The slurry pump generally adopts an external flushing tank. The seal flushing water in the tank can be selected according to the use conditions of the mechanical seal. It can ensure that the second mechanical seal can be flushed and lubricated to take away the heat generated by the mechanical seal, further improving the service life of the mechanical seal.

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