Anti-corrosion anti-dry-grinding shaft seal

Abstract

The invention discloses an anti-corrosion anti-dry-grinding shaft seal. The shaft seal is mounted on a centrifugal pump main shaft. The shaft seal comprises a sealing box assembly and a mechanical seal. The mechanical seal comprises a static ring and a moving ring. The anti-corrosion anti-dry-grinding shaft seal is characterized in that the sealing box assembly is fixedly connected with a pump shell, the moving ring is fixed to a main shaft, and the moving ring is located in a pump cavity and is in contact with conveying material liquid; the sealing box assembly comprises a sealing box, a sealing box pressing rear cover and a static ring pushing elastic ring arranged in the sealing box, wherein the sealing box pressing rear cover and the sealing box are arranged in a split or integrally manner; the two ends of the static ring pushing elastic ring are compressed between the sealing box pressing rear cover and the static ring, the static ring pushing elastic ring is in an elastic pressing state, a static ring friction pair is in contact sealing with a moving ring friction pair, and a rigid partition is fixedly connected to the sealing end surface of the sealing box and the pump shell; and the peripheral surface of an inner hole of the rigid partition is in contact sealing with the outer peripheral surface of the static ring, and a liquid storage cavity is defined by the outer peripheral surface of the static ring pushing elastic ring, the sealing box pressing rear cover, the rigid partition and the static ring.

Description

technical field [0001] The invention relates to the field of centrifugal pump shaft seals, in particular to a centrifugal pump shaft seal for conveying corrosive slurry containing chloride ions and the like. Background technique [0002] In the flue gas desulfurization process of iron and steel enterprises and coal chemical enterprises, and the wet smelting process of nickel and cobalt, centrifugal pumps must be used to transport clear liquid or slurry containing chloride ions. And this kind of medium is very corrosive to metal, especially the pump shaft seal, which requires metal components such as metal springs, bolts and nuts, and these components are easily corroded by contact with the transported chloride-containing liquid or corrosive gas. Hence the idea of ​​developing pump shaft seals without metal components. [0003] Some people use a lip-shaped rubber seal with a dynamic seal composed of a ceramic bushing and a glass fiber reinforced plastic sealing box to transp...

AI Technical Summary

Problems solved by technology

This kind of pump shaft seal has excellent anti-corrosion performance, and all mechanical seal components will not be corroded by the conveying medium, but there are the following disadvantages: First, the conveying medium in the pump chamber is in contact with the rubber push ring, and the rubber push ring is immersed In the conveyed medium, the acidity or alkalinity in the conveying medium will produce a reduction reaction of the vulcanizing agent on the rubber push ring, which will soften the rubber push ring and lose its elasticity, thereby causing the seal to fail

The second is that the outer circumference of the rubber elastic ring that pushes the static ring is connected with the fluid in the pump chamber, so the pressure change of the fluid in the pump chamber acts on the outer spherical surface of the rubber ring. When the fluid is under negative pressure, the rubber ball will expand radially. , the axial contraction reduces the specific pressure between the dynamic and static rings, which in turn causes leakage. When the fluid pressure in the pump chamber is high, the same fluid pressure also acts on the outer spherical surface of the rubber elastic ring, causing the rubber ring to shrink radially, and the shaft elongate, and then push the static ring, so that the specific pressure of the working surface of the dynamic and static ring of the mechanical seal increases, and accelerates the friction and wear of the dynamic and static ring

The third is that the machine seal cannot be equipped with external cooling water, so as long as the pump loses fluid and runs, the machine seal will be burned by dry grinding

[0005] Therefore, the mechanical seal of the metal-free assembly still needs to be improved. For this reason, the inventor discloses a metal-free mechanical seal with cooling water flushing in the patent 201420286999. figure 2 ), that is, a liquid filling hole 4.1 is set on the sealing box 4 of the prior art, a liquid hole 3.1 is set on the spherical rubber ring, a flexible partition is set between the sealing box cavity and the pump cavity, and the main shaft is set to prevent cooling. The water leaking shaft seal 5, through innovation and improvement, the rubber push ring in the original technology has no contact with the conveying liquid in the pump chamber, and the push ring will not be affected by the acid-base medium in the pump chamber and will not be deformed , and the seal can also run empty, and has good anti-dry wear performance, but there are still the following problems that are difficult to solve: First, because the cavity between the pump cavity and the seal box is made of a "U" ring The flexible diaphragm of the groove, the flexible diaphragm will be stretched and compressed or pushed away due to the pressure change of the fluid in the pump chamber. The specific pressure between the dynamic and static rings, that is, the fluid pressure in the pump chamber is high, and the flexible diaphragm is pushed to The outside of the pump chamber, and then the dynamic and static rings of the mechanical seal are disengaged, resulting in the delivery liquid in the pump chamber leaking into the cooling water chamber, making the pump seal invalid

The second is that the shaft seal 5 that seals the cooling water has a short service life, generally only 3 to 4 months, and there is still a hidden danger of cooling water leakage

The third is to consume 2~3 tons of cooling water per day, which is very considerable

[0006] Therefore, the metal-free component mechanical seal with good anti-corrosion performance in the prior art still has the shortcomings of unstable performance and leakage of cooling water, and there is still a need for improvement

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