Improvement of slag slurry gate valve structure for throttling

Due to errors in selection calculations and actual pipe network resistance, the slurry pump has a higher flow rate during actual operation. In order to achieve production balance, it is necessary to use gate valves on the outlet pipeline to regulate the flow rate to meet the requirements of the production process. Gate valves can generally only be used for opening and closing shut-off, and can only be used for throttling when the opening degree is less than 40%. When used for throttling in slurry pipelines, the service life is very short. When throttling the gate valve, cavitation and backflow occur, forming a large number of deep grooves and pits in the valve body groove and gate plate, leading to premature failure of the gate valve, increasing maintenance costs, and seriously affecting the stable operation of the production system.

When the slurry passes through the small channel formed by the gate and valve body, the flow area shrinks locally, the flow velocity increases sharply, and the pressure drops sharply. After the instantaneous pressure drops to the vaporization pressure, bubbles will be generated. After throttling, the increased pressure compresses the bubbles, forcing them to rupture and causing damage to the material. At the same time, after passing through the locally contracted small section, the slurry separates from the pipe wall and creates a low-pressure area on the back of the gate, forming backflow. The reflux slurry is mixed with bubbles and slag slurry, and is repeatedly washed in the high-pressure and low-pressure areas, causing serious damage to the back of the gate and the bottom of the valve body groove, especially at the crescent shaped sharp corners formed between the two sides of the gate and the valve body, where the back of the gate is most severely damaged. At the same time, it will also generate noise and vibration.

In order to improve the wear resistance of gate valves, an embedded lining structure is adopted, and the lining material can be rubber or wear-resistant alloy. Rubber materials have low cost and good sealing performance, but poor wear resistance, short lifespan, heavy maintenance workload, and inconvenient replacement, resulting in high operating costs. Wear resistant alloy materials have good wear resistance, lower cost than integral forging wear-resistant alloys, and higher cost-effectiveness than rubber. The lining can be replaced, and the valve body can continue to be used for a long time. The lining is made of high chromium wear-resistant alloy with high hardness and wear resistance. After heat treatment, its hardness reaches 58-62HRC, and its wear resistance is good.

In order to reduce the erosion of the gate and valve body groove caused by backflow, a partition is installed in the outlet sleeve. The partition forces the medium to form a secondary diffusion, controlling the large-scale backflow in the area below the partition, reducing the erosion of the backflow on the gate and valve body groove. At the same time, it reduces the pressure drop and lowers the likelihood of cavitation.