Structural characteristics of power station gate valve of power station gate valve

1. There is no friction in opening and closing. This function completely solves the problem of traditional valves affecting the sealing due to the friction between the sealing surfaces.

3. Single seat design. It eliminates the problem that the medium in the cavity of the valve affects the safety of use due to abnormal pressure increase.

4. Low torque design. The valve stem with special structure design can be easily opened and closed with only a small handle valve.

5. Wedge-shaped sealing structure. The valve is sealed by the mechanical force provided by the valve stem to press the ball wedge to the valve seat, so that the sealing of the valve is not affected by the change of pipeline pressure, and the sealing performance is reliably guaranteed under various working conditions.

6. Self-cleaning structure of sealing surface. When the ball is tilted away from the valve seat, the fluid in the pipeline passes evenly at 360 degrees along the sealing surface of the ball, which not only eliminates the local scouring of the valve seat by the high-speed fluid, but also washes away the accumulation on the sealing surface, so as to achieve the purpose of self-cleaning.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following influential first-line brands of water system valves and industrial valves can be used as a reference, but for reference only: Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

1) Low resistance to fluid flow; The torque required for opening and closing is small; The flow of media is not restricted; There is no water hammer phenomenon in opening and closing; The shape structure is relatively simple, and the manufacturing process is good.

2) The overall size and installation height are larger, and the required installation space is also larger; In the process of opening and closing, the sealing surface has relative friction, great wear, and even easy to cause abrasion at high temperatures; Gate valves generally have two sealing surfaces, which adds some difficulties to machining, grinding and maintenance.

3) Gate valves have a wide range of applications. It is usually used for water supply lines with a nominal diameter greater than or equal to DN50.

Features of Gate Valve:

1.Low fluid resistance. The internal medium channel of the gate valve body is straight, as mentioned above, the gate valve can only be fully opened or closed, when the gate valve is fully open, the flow resistance of the medium passing through the gate valve body channel is close to 0, and the flow resistance is very small.

2.The switch operation is labor-saving. Because when the gate plate of the gate valve is opened and closed, the direction of movement is up and down, which is perpendicular to the direction of movement of the medium in the valve body channel, and the opening and closing operation of the gate valve is more labor-saving than that of the globe valve.

3.Two-way circulation. The gate valve is a two-way valve, that is to say, the flow direction of the medium in the valve body channel is not limited, and the medium can flow arbitrarily from both sides of the gate valve, without affecting the normal opening and closing of the gate valve.

Therefore, the gate valve is suitable for installation in pipelines where the flow direction of the medium may change.

4.Good sealing performance. The gate valve is used to cut off the medium, so in terms of sealing performance, the sealing performance of the gate valve is better than that of the butterfly valve.

Commonly used valves are: gate valves, globe valves, check valves, ball valves, butterfly valves, safety valves, regulating valves, plug valves and so on.

Gate valve: Gate valve refers to the valve in which the shut-off part (gate) moves in the vertical direction along the channel axis, and is mainly used as a cut-off medium on the pipeline, that is, fully open or fully closed. In general, gate valves cannot be used as flow regulators.

It can be applied to low temperature pressure or high temperature and high pressure, and can be based on different materials of the valve. However, gate valves are generally not used in pipelines that transport slurry and other media.

The main valve of the turbine is installed between the pressure pipeline and the volute, and the main valve only has two working positions: fully open and fully closed, and does not adjust the inlet flow rate of the turbine, and its functions include the following aspects.

1. Provide safe working conditions for unit maintenance. When the power station adopts a joint or grouped water supply mode in which a pressure pipeline supplies water to two or more units, one of the units can be overhauled and its main valve can be closed, so as to form a safe working condition without affecting the operation of other units.

2. Reduce the water leakage of the unit when it is shut down, and shorten the time required for starting when it is turned on. The water guide mechanism of the turbine is often not closed tightly, and there is a large amount of water leakage after the shutdown. This not only wastes water energy, but also causes cavitation damage in the crevices due to water leakage.

According to statistics, the general guide vane leakage is about 2%-5% of the maximum flow rate of the turbine, and the serious can reach 8%, and the small unit with a high water head can not even stop due to excessive water leakage. When the unit is shut down for an extended period of time, closing its inlet valve can greatly reduce water leakage. When the unit is shut down for a short time, the pressure pipeline inlet gate is generally not closed.

Because this will release the water in the pressure pipe due to the leakage at the end of the pipe, and the pressure pipe needs to be filled with water again before starting again, which not only prolongs the starting time of the unit, but also makes the unit unable to maintain the standby state at any time, and loses the flexibility and quickness of the operation of the hydropower station. Closing the inlet valve reduces both leakage and the time it takes to start the unit again. For medium and high head power stations with long pressure pipes, this role of the main valve of the turbine is more obvious.

3. Prevent the expansion of the crew flight accident. When the unit or speed control system fails, the turbine can not be shut down in time may cause the crew to escape the accident, at this time, the speed signal should automatically issue an instruction to close the main valve of the turbine urgently, quickly cut off the water flow, prevent the unit from flying, and avoid the expansion of the accident. If the main valve of the turbine is not set, the inlet gate of the pressure pipe should be closed quickly, but because it takes time for the pressure pipe to empty, the unit will take a long time to escape.