China Three Gorges has filed a patent for a variable-flow-path air valve designed to prevent water hammer. The valve includes a swing check valve and a ball valve seat, allowing air to be taken in through an intake-exhaust port and discharged only through the same port. The valve body is shaped like a hollow pot with a regular polygon middle convex part. GlobalData’s report on China Three Gorges gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData's company profile on China Three Gorges, AI assisted CAD was a key innovation area identified from patents. China Three Gorges's grant share as of June 2023 was 1%. Grant share is based on the ratio of number of grants to total number of patents.
Variable-flow-path air valve for water hammer prevention
A recently filed patent (Publication Number: US20230160515A1) describes a variable-flow-path air valve designed to prevent water hammer. The valve body is shaped like a hollow pot with an upper necked part, a lower necked part, and a middle convex part. The middle convex part has a regular polygon shape. The valve body has a fluid inlet-outlet port at the bottom and an air intake-exhaust port at the top, which is sealed with a sealing ring. Below the air intake-exhaust port, there is a ball valve seat and a floating ball. The ball valve seat consists of a grid, a guide sleeve, and a floating ball base with flow holes. The valve body and the ball valve seat are connected by a guide sleeve holder. The lower half of the middle convex part has at least one swing check valve that opens inward. The swing check valve includes a swing valve disc, a variable-flow-path air inlet controlled by the disc, a device for limiting the opening degree of the disc, and a sealing device.
The patent also describes a method for using the variable-flow-path air valve for water hammer prevention. In the normal water delivery state, the air valve is closed, and the water pipeline operates normally with no tendency for water hammer. The water lifts the floating ball to seal the air intake-exhaust port, preventing air and water from entering or exiting. During normal water delivery, a small amount of air is released from the pipeline, which gathers into the valve body and is quickly discharged through the air intake-exhaust port. In the water hammer prevention state, when negative pressure occurs in the pipeline, the water in the valve body is attracted by the pipeline, causing the floating ball to drop and open the air intake-exhaust port. Air enters the valve body through the air intake-exhaust port and the variable-flow-path air inlet, and then enters the water pipeline. When the pressure in the pipeline recovers, the air is discharged from the valve body only through the air intake-exhaust port. As the pressure in the pipeline gradually recovers, the air in the pipeline enters the valve body and is discharged, while the water in the pipeline enters the valve body until the floating ball rises to contact the sealing ring, closing the air valve and returning the water pipeline to the normal water delivery state.
The patent also includes a design method for the air valve, which involves determining the inlet and outlet flow path areas of the valve through an analysis of the hydraulic transient process. The analysis considers different flow conditions, including subsonic speed, sonic speed, and supersonic speed.
Overall, this patent describes a variable-flow-path air valve and its method of use for preventing water hammer in water pipelines. The valve design includes swing check valves, a floating ball, and a sealing ring to control the flow of air and water. The method outlined in the patent allows for the normal operation of the water pipeline while preventing water hammer.