Inlet valve
In the water turbine system of the turbine, according to the operation and maintenance of the hydropower station, corresponding gates or valves are installed at different positions, and the valve in front of the turbine volute is usually called the inlet valve.
classification
The types of inlet valves that are widely used in hydropower stations are: butterfly valves, gate valves and ball valves.
(1) Gate valves are often used in small power plants with a pipe diameter of less than 1 m and a high working head.
The gate valve has the advantages of simple structure, convenient maintenance, low cost, small hydraulic loss when fully opened, good sealing performance when fully closed, and does not open or close by itself due to water flow impact. Therefore, no lock ingot device is needed. However, the volume and self-importance, the operation force required for opening and closing is large, the time is long, and the dynamic water closing vibration is strong.
The gate valve is composed of a valve body, a valve cover, a valve stem and a shutter. According to the seat type, the gate valve has a wedge seat type and a parallel seat type. The wedge valve seat type ram is divided into a single ram and a double ram. The double ram is divided into two types: an open rod and a dark rod.
(2) Butterfly valve Butterfly valve is called butterfly valve, which is widely used in power stations with water head below 200m.
The butterfly valve is mainly composed of a cylindrical valve body and a discus-shaped shutter which can be pivoted in the valve body and other accessory parts.
When the butterfly valve is closed, the valve is in contact with the valve body to close the water flow path. When opened, the valve is parallel to the direction of the water flow, and the water flows around the sides of the valve. The butterfly valve has the advantages of small size, light weight, simple structure, low cost, convenient operation and quick closing under water and water. However, the valve has the disadvantage of affecting the flow state of the water, causing hydraulic loss and large water leakage.
(3) Ball valve ball valve is used for large and medium power stations with a water head greater than 250 m.
It has tight shut-off, minimal water leakage, and the seal is not easy to wear. There is almost no hydraulic loss when fully opened. The operating torque required during opening and closing is very small, and it can be used for emergency shut-off of moving water. The amplitude is smaller than that of the butterfly valve, but the ball valve is large in size, complicated in structure, heavy in weight and high in cost. Ball valves are generally operated hydraulically or hydraulically.
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