I. Overview
Due to the selection calculation and the actual pipe network resistance error, slurry pump in actual operation, the flow is too large. In order to achieve production balance, the need to use the gate valve on the outlet pipe to regulate the flow to meet the requirements of the production process. Gate valve generally only open, close the use of off, open the degree of less than 40% in order to play the role of throttling, in the slurry pipeline to do when used, the life expectancy is very short. When the valve is throttled, cavitation and backflow are generated, and a large number of deep grooves and pits are formed in the valve body groove and the gate plate, leading to premature valve failure and increased maintenance costs, which seriously affect the stable operation of the production system.
Second, analysis
When the slurry passes through the small channel formed by the gate and the valve body, the overcurrent area contracts locally, the flow rate increases sharply, and the pressure suddenly drops. Immediately after the pressure drops to the vaporization pressure, air bubbles will be generated. After throttling, the elevated pressure compresses the bubbles, forcing the bubbles to rupture and causing damage to the material. At the same time, the slurry through the local contraction of the small cross-section, and the pipe wall off the back of the gate to produce low pressure area, the formation of reflux. Reflux slurry mixed with bubbles and slurry in the high-pressure zone and low pressure zone repeated scouring, so that the back of the gate and the valve at the bottom of the tank to form a serious damage, especially on both sides of the gate and the valve body formed crescent sharp gate The back of the most serious. At the same time, noise and vibration can also occur.
Third, improve
In order to improve the wear resistance of the valve, the use of a mosaic lining structure, the lining material can be rubber or wear-resistant alloy. Low cost of rubber material, good sealing performance, but poor wear resistance, short life, large maintenance workload, and inconvenient replacement, high operating costs. Wear-resistant alloy material wear resistance, lower than the overall cost forging wear-resistant alloy, rubber than the high cost, the bushing can be replaced, the valve body can continue to long-term use. Bushing selection of high hardness, wear-resistant high chromium wear-resistant alloy casting, the hardness after heat treatment up to 58 ~ 62HRC, good abrasion resistance.
In order to reduce back flushing to the gate and the body groove, a spacer is provided in the outlet sleeve. The diaphragm forces the medium to form a secondary diffusion that will control a large area of back flow within the area below the diaphragm, relieving flushing of the ram and body groove. At the same time, the pressure drop is reduced, reducing the possibility of cavitation.
Fourth, the conclusion
Gate valve with baffle structure, which can effectively distribute pressure to avoid cavitation. At the same time using high wear-resistant alloy lining material to improve the slurry pipeline throttle valve life.
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Anchor And Other Parts,G70,G80,G100 High-test Riggings Co., Ltd. , http://www.chsteelchain.com
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