Localization Research and Application of Large Submersible Pump Sealing System

As a result, the sealing performance achieved the desired effect and effectively replaced the import.

The imported large vertical submersible pump is widely used in municipal sewage discharge systems in large and medium-sized cities due to its large pumping flow and drainage efficiency. According to rough estimates, the national sewage treatment plant has hundreds of such high-power diving chestnuts. The large submersible pump has long been immersed in sewage and has the advantages of stable operation, reliable sealing, high safety and low failure rate. It is the key equipment for urban sewage pumping stations and sewage treatment plants. However, due to the high import price and the difficulty in obtaining spare parts, the long-term impact on production is urgently needed to solve the problem of localization. Based on the experience accumulated in the long-term use and maintenance of large submersible pumps, we have carried out research and application of localization of large-scale diving and sealing systems. In practice, we have developed a set of mechanical seals and a set of 0-shaped rubber seals installed on the original imported submersible pump.

After a period of operation, it shows that the sealing performance has achieved the expected effect, meets the production requirements, and effectively solves the long-standing problems such as expensive imported spare parts and long ordering period affecting production. I would like to introduce the following.

External static sealing system research The external static sealing system of large submersible pump mainly refers to the joint sealing between the parts and components of the pump body, the sealing of the power cable and the interface where the control cable enters. These parts are sealed in a 0-shaped rubber ring for the extrusion of the sealing element, relying on long-lasting compression deformation to maintain the sealing performance. According to the chemical nature of the sewage medium, we have selected the fluorine rubber with strong water resistance and acid and alkali resistance as the original water pump technology 2000.5. According to the accuracy requirements of the national standard, the hardness of the Shore is hardened by the mold. Type 0 rubber ring. Because fluororubber has the advantages of small compression set, anti-aging, good temperature performance, etc., it still has reliable sealing performance after being subjected to long-time extrusion deformation.

Internal dynamic sealing system research The internal dynamic and dense system of a large submersible pump mainly refers to the rotary sealing part of the impeller shaft. As shown, the pump employs two sets of upper and lower mechanical seals between the impeller and the bearing, and in a series configuration forms a set of dual mechanical seal systems that prevent sewage from entering the stator chamber up the shaft surface. The viscous lubricating oil is used as the sealing liquid between the two sets of mechanical seals. This aspect provides a good cooling lubricating medium for the normal operation of the upper mechanical seal end face, and at the same time can isolate and reduce the resistance value of the micro-leakage sensor of the lower mechanical seal end face, so that We can always judge the working condition of the upper mechanical seal. Similarly, the working condition of the lower mechanical seal can also be known by periodically checking the degree of emulsification of the oil in the lubricating oil chamber.

The lower mechanical seal is located at the rear of the impeller. When the pump is working, it will withstand the pressure action and pressure fluctuation of the sewage medium in the chestnut. It is affected by the chemical corrosion of the sewage medium and is affected by the abrasion of the hard surface of the seal on the sealing friction end face. The combination of factors will cause vibration, corrosion, wear, thermal deformation and other problems in the lower mechanical seal during operation. Therefore, proper design, strict processing and proper installation of the lower mechanical seal are the key to ensuring long-term reliable operation of the large-scale diving chest seal system. This is a deep experience from everyday use and maintenance.

The development of the lower mechanical seal is based on the working conditions of the large submersible pump. After analysis, we have selected the single-end, built-in, multi-spring, non-equilibrium type for the lower mechanical seal. The static ring is mounted on the pump body, and two compression type 0 rubber rings are mounted on the static ring to prevent the sewage from escaping through the outer surface of the static ring to the oil chamber on the back side thereof, and the moving ring member is mounted on the impeller, relying on one The tightening positioning spring pre-compresses the component parts into an integral moving ring component, and the driving pin drives the spring seat to rotate the moving ring component. A compression type 0 rubber ring is installed behind the moving ring to prevent the sewage from escaping the oil chamber along the inner surface of the moving ring. The 12 small springs evenly distributed along the circumference transmit the spring force to the end face of the moving ring through the push ring and the 0-shaped rubber ring, providing the end face pressure required for the close contact with the end face of the stationary ring, and providing the floating property in the rotation of the moving ring. And compensatory.

3.2 Selection of sealing parts materials Because the sewage medium contains solid particles, the hard ring and the static ring end face should be selected as hard-hard material pairs to overcome the abrasion of the friction end faces. Therefore, we believe that the choice of nickel-based tungsten carbide with high hardness, low friction coefficient, corrosion resistance and strength 是 is an ideal material for the manufacture of dynamic and static rings. The moving ring and the static ring 0-shaped rubber ring still select a fluorine rubber material which is resistant to water, corrosion, aging, and compression set. Because the small spring has a thin wire diameter and is easily damaged by chemical corrosion and fatigue stress corrosion, the austenitic stainless steel 0Crl8Nil2Mo2Ti material with strong corrosion resistance is selected. The spring seat, push ring and drive pin are made of 0Crl8Ni9Ti corrosion-resistant stainless steel.

The machining accuracy and processing of the sealing parts are the most important parts of the mechanical seal, and their machining accuracy will directly affect the sealing effect. We have redesigned the dimensional accuracy, shape tolerance and surface roughness of each part by carefully measuring the original mechanical seal parts and then following the requirements of the national standard mechanical seal technical conditions. In particular, the friction end faces of the moving ring and the stationary ring are finely ground and polished, and strive to achieve extremely high flatness and mirror technical requirements. In addition, we used the elastic testing machine to test the original spring, and plotted the piston pump that can transport large solid waste water. The valve process of the shaftless company of the valve company of Orrita Company of Germany, Germany. English]//WorldPumps (UK). -1997, (373). -21 Pressure-deformation diagram of the 2000.5 spring of the small-size double-pump technology of All-FloPump, USA. According to this figure, the heat treatment process curve of the spring is designed to ensure the consistency of the performance of multiple springs. After all the sealing components have been cleaned and assembled, the dynamic ring floating inspection, spring pressure inspection and static pressure simulation test are also carried out to ensure the long-term reliable working life of the mechanical seal. 0 The large-scale submersible pump with high price is sunk in the water for a long time. Under the work, the technical requirements for the internal dynamic seal and external static sealing system of the scorpion are extremely high. Any slight leakage and the drive motor system of the pump will cause short circuit and other electrical faults, resulting in significant damage to the pump. Economic losses. Therefore, in order to ensure the safe and reliable operation of large submersible pumps, the operation of the sealing system should be monitored and periodically checked, and the failed sealing components should be replaced in time. The successful localization of the imported large-scale diving chest sealing system has not only greatly reduced the maintenance cost, but also made it possible to ensure the timely repair and commissioning of the pump, and no longer rely on the arrival of imported sealing accessories to stop the production.

(Editor Wang Zhenhua) Self-priming rotary diaphragm of Linear Drive Company of Germany ASFThomas Company (English) // WorldPumps (Transporting Chemistry and Abrasive Fluid of British British Garvin Honey Co., Ltd., Body Rotor Piston Pump [English] // WorldPumps ( UK).-1997, (375).-25 company's large volume flow radial piston pump [Germany] / / F + H: Fordern

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