The heavy hammer butterfly valve is a sophisticated mechanical and hydraulic system designed for reliable and automatic shutdown in hydropower plants. It consists of a butterfly valve body, a hydraulic bypass valve, a counterweight, a release mechanism, a manual or electric pump, a rack-driven cylinder, and an electronic control unit. The oil from the pump is directed into the rack-driven cylinder, where the piston moves to rotate the gear on the main shaft of the butterfly plate, thereby opening the valve and lifting the counterweight to its highest position. A pawl on the weight locks into place via the release spindle, which is held by an electromagnet and a holding device. In the event of an emergency, the electronic control system triggers the release of the electromagnet, allowing the counterweight to fall under its own weight and close the valve automatically.
The hydraulic system employs a two-stage throttling mechanism to regulate the closing speed of the valve. During the initial stage, the closure is slowed down to minimize water hammer effects, while in the second stage, the speed increases gradually to control the rise in water pressure effectively.
In terms of technical features, this dual-purpose hydraulic system is compact and easy to operate. It can function even without external power, relying on gravity to initiate shutdown. The system also offers automatic protection against over-speed, bearing overheating, and generator demagnetization. It includes two-stage closing functions, with the electromagnet-controlled locking mechanism ensuring safe and low-force operation.
Key technical parameters include a working pressure of 1 MPa, various diameters such as φ400, φ500, φ600, φ800, φ1000, and φ1200 mm, a maximum head of 100 meters, and a rated head of 145 meters. The manual opening time is approximately 5 minutes, while the electric opening takes about 1 minute. The fast-closing stage lasts between 5 to 10 seconds, and the slow-closing stage ranges from 10 to 50 seconds. The over-speed protection range is set at 1.8 times the rated speed, and it is adjustable.
This type of valve has been successfully applied in the Chaitan Hydropower Plant in Linhai City, Zhejiang Province. Two D741X-10 heavy hammer butterfly valves were installed in a hybrid-type power station. The plant features a 1100-meter-long pressure tunnel with a diameter of 2.6 meters, a 50-meter-long pressure pipe with a diameter of 1.2 meters, and a design head of 45.5 meters. The turbines used are HL220-WJ-50A, and the generators are SFW-630-6/990 (reactive shunt excitation) with a rated voltage of 400V and capacity of 630kW.
Since being connected to the grid in January 1991, the two units have operated for a total of 7,780 hours by March 1993. The valves have performed reliably, with a 100% correct operation rate—opening and closing 203 times each. The average electric opening time was 55 seconds, with a fast-closing time of 5 seconds, reducing the speed increase to within 40%. The slow-closing time was set to 20 seconds, limiting the water pressure rise to 21%.
During accidents, if the unit exceeds 1.4 times the rated speed, the speed measuring device triggers an automatic release of the counterweight, closing the inlet valve and preventing further damage. This enhances operational safety significantly.
In conclusion, the heavy hammer butterfly valve improves equipment reliability and ensures safe shutdowns. It reduces the workload for operators and maintenance teams, saving approximately 80,000 yuan annually and cutting the number of on-duty staff by four. Moreover, the valve can automatically trip during power loss, eliminating the need for standby DC power. In some power plant designs, where finding the right guide vane closing time is challenging, the two-stage closing feature of the heavy hammer valve provides a more reliable and economical solution compared to artificial resistance methods.
Vacuum Components
Vacuum Components are integral parts of a Vacuum system, each playing a distinct role. The Vacuum Pump or Vacuum Blower, for instance, acts as the powerhouse, creating vacuum. However, it's important to note that perfect vacuum, or 100% vacuum, is not achievable on Earth. When designing machines that require a vacuum source, a reliable vacuum pump is essential, but so are vacuum thread connections, valves, and other components. These components connect and control the vacuum system, ensuring its efficient operation.
In some cases, electrical control vacuum components are necessary. The vacuum switch, for example, monitors the vacuum level and sends signals to the solenoid valve to adjust the system to the desired vacuum level. This switch can be an integral part of the vacuum system, ensuring consistent operation and precise control over the vacuum environment.
It's essential to choose the right vacuum components for your specific application. Each component has its unique function and contributes to the overall performance of the vacuum system. From pumps and gauges to valves and switches, understanding the role of each component is crucial for designing and maintaining a reliable and efficient vacuum system.
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