JPS62270880A - Hammering load relaxation method - Google Patents

Abstract

PURPOSE:To prevent any hammering at the time of valve sudden closure from occurring without fail, by connecting a branch valve, installing a valve to be opened at the time of sudden closing a valve in a main pipeline, to this main pipeline as well as connecting a tank, having an air layer subject to pressure regulation, to this branch pipe. CONSTITUTION:When a valve 2 of a main pipeline 1 is suddenly closed, simultaneously a valve sudden closing signal is inputted into a control chamber 10 by way of a cable 12, whereby a valve opening signal for a valve 4 in a branch pipe 3 is outputted from this control chamber 10, and an internal fluid 6 in the main pipeline 1 is made to flow toward the branch pipe 3 by what the valve 4 is opened. And, at this time, a signal out of a pressure detector 11 on the main pipeline 1 is outputted to the control chamber 10, and in conformity with the pressure signal, an air pump 9 is operated so as to keep such pressure as preventing air 7 in the tank 5 installed at a tip of the branch pipe 3 from flowing back, while a valve 8 is controlled. With this constitution, at the time of sudden closure of the valve 2, an air layer 7 inside the tank 5 is made to function as a damper, whereby a reaction variation is made so as to be quickly restrainable.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a piping system installed in a power generation plant such as a nuclear power generation plant, and the present invention relates to a piping system installed in a power generation plant such as a nuclear power generation plant. This invention relates to a method for alleviating the hammering load that occurs.

[Conventional technology]

Conventional methods for preventing and alleviating the hammering load caused by pressure changes when the flow suddenly breaks are generally described in ``Introduction to Water Hammer (Nisshin Publishing), written by Shigeyoshi Yokoyama, pages 133 to 140. As discussed in ``Page 1,'' there are two main methods: methods for preventing the generation of negative pressure and methods for preventing pressure rise. One way to prevent negative pressure is to install a flywheel. Install a surge tank. As a method to prevent pressure rise, such as by providing an air chamber, a slow-closing check valve is provided. Various methods have been used, such as providing a check valve with a bypass. However, many of these conventional methods are particularly effective for piping lines that include pumps, such as in hydroelectric power plants, and are effective for piping systems that do not include pumps, such as in nuclear power plants (for example, from the reactor pressure vessel to There has been no effective preventive measure for systems in which water hammer loads can be generated in systems where fluid flows (such as systems in which fluid flows), systems that are affected by the pressure of incompressible fluids such as extraction pressure, water pressure, etc.

As mentioned above, if a large hammering load is considered in a piping system that does not include a pump, a piping system that is subject to high pressure, or a system that is driven by the fluid pressure of an incompressible fluid, use piping support. The design was designed to increase the strength of the system by adding more units.

The number of manufacturing steps was large.

[Problem that the invention seeks to solve]

Among the above-mentioned conventional techniques, methods of providing various check valves to prevent pressure increases are used in piping systems such as nuclear power plants, systems that utilize the fluid pressure of incompressible fluids such as hydraulic pressure, water pressure, etc. Compared to hydroelectric power plants, check valves used in piping systems where high-pressure fluid acts require extremely high specifications such as strength, performance, and reliability.
It was impossible.

Regarding methods for preventing the generation of negative pressure, when installing an air chamber, the pressure in the air chamber should be cannot be adjusted according to fluctuations in the pressure inside the piping, so when the internal fluid pressure is high, the air layer in the air chamber becomes very small, making it impossible to prevent sudden shutoff of the internal flow due to sudden closing of the valve, and the internal fluid When the pressure is low, the problem arises that air flows backwards into the pipes. Furthermore, in a system driven by the action of an incompressible internal fluid, simply reducing the size of the air layer would not cause the desired symmetrical action, which was out of the question. Regarding the method of installing a surge tank, in the case of high-pressure internal fluids, it is necessary to install a very large tank, which is a big hindrance to the lightweight and compact design that has been required for nuclear power plants in recent years. In a system that is driven by the pressure action of internal fluid, the fluid pressure will naturally act on the surge tank, and it will not perform its function. Additionally, as an improved method of installing a surge tank, there is a method of installing a one-way surge tank in which a check valve is installed between the piping and the tank to shut off the flow of fluid from the piping into the tank. For high-pressure internal fluids, a very large tank must be installed as well, and in systems that are driven by the action of incompressible internal fluids, when the inside of the piping becomes negative pressure, it is necessary to install a surge tank. The fluid flows in and prevents a pressure drop, but when the pressure inside the piping increases, this device is not effective in preventing a pressure rise, so there is a problem that it is not very useful in preventing hammer loads. .

As mentioned above, there are various methods for preventing hammering loads, but all of them have major drawbacks and have not been used in practice.

The purpose of the present invention is to eliminate the above-mentioned disadvantages and provide a more effective method for alleviating hammering loads in systems that utilize high-pressure piping or the pressure of incompressible internal fluids, such as in 1M child power generation plants. There is a particular thing.

[Means for solving problems]

A hammering load is generated when the flow in a pipe is abruptly interrupted by the sudden closing of a valve, and as a result, a pressure wave is generated due to a sudden pressure rise in the interrupted section. The following method can be used to prevent this hammering load. A branch pipe is provided near the valve that causes the hammering load, and is connected to a tank consisting of two layers of fluid and air inside the main pipe via the normally closed valve. Both the valves on the main pipe and the valves on the branch pipe are controlled in a control room so that the valve on the main pipe closes and the valve on the branch pipe opens at the same time.

In addition, the air layer in the tank is further connected to the air pump,
The pressure is sensed by a pressure detector attached to the main piping, and the pressure inside the tank is maintained at a negative pressure that prevents air from flowing back into the main piping. Such control is possible because it is theoretically known that the pressure pulsations that cause hammering usually have a variation range that is equal to the internal fluid.

The above purpose is achieved by using this method.

As mentioned in the previous chapter, the disadvantages of the various conventional methods for preventing hammering can be overcome in all aspects, and it is also easy, simple, and efficient to prevent and alleviate hammering loads. It is possible to achieve this.

[Effect]

At the same time as the main pipe valve suddenly closes, a signal is sent from the control room to the valve on the branch pipe to open it. Due to this action, the fluid inside the pipe is directed toward the branch pipe, thereby preventing sudden interruption of the flow inside the pipe, which would normally cause a hammering load. In addition, the internal pressure of the branch pipe and the two-layer tank beyond it is maintained at a negative pressure to prevent backflow into the pipe, so the flow is directed towards the branch pipe and gradually slows down due to the air layer. Become. Additionally, the air layer within this tank acts as a damper to quickly suppress pressure fluctuations within the branch pipe.

Through the above-described actions, it is possible to alleviate the hammering load caused by sudden closing of the valve in the piping system.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The internal fluid 6 of the main plumber sends a sudden valve closing signal to the control room 1 via the cable 12 at the same time as the main pipe valve 2 suddenly closes.
A signal is also sent from the control room 1o via the cable 12 to open the valve 4 installed on the branch pipe 3. In this way, the internal fluid 6 of the main pipe will be directed towards the branch pipe 3.

In addition, a signal from a pressure detector 11 installed on the main plumber is sent from the control room 10 to ensure that the air 7 in the tank 5 installed at the end of the branch pipe 3 to the main plumber does not flow back. Air pump 9 via cable 12 to maintain pressure
is operated to maintain the pressure inside the tank 5 at a predetermined pressure, and the valve 8 on the tank 5 is closed.

In this state, the valve 2 closes suddenly and the internal fluid 6' flows toward the branch pipe 3, but this flow is caused by the air layer 7 acting as a damper, which reduces the flow inside the pipe. One reaction force fluctuation can be suppressed rapidly without sudden shutoff.

Therefore, according to this embodiment, there are more than one effect,
It is possible to reduce the hammering load.

〔Effect of the invention〕

According to the present invention, reaction force fluctuations due to sudden shutoff of internal fluid in a system driven by fluid pressure of extremely high-pressure internal fluid such as the piping system of a nuclear power plant or incompressible fluid such as hydraulic pressure or water pressure The hammering load generated from
This not only significantly improves the reliability and safety of the piping system, but also greatly reduces excessive piping support in consideration of hammering loads, reducing large-scale design and construction man-hours. There is an effect that it can be done.

[Brief explanation of drawings]

FIG. 1 is a pipe system diagram using a hammering load prevention method according to an embodiment of the present invention. Figure 2 shows the structure of a conventional hammer prevention device using an air chamber, and Figure 3 shows the structure of a device using the one-way surge tank method, which is connected to a surge tank via a check valve. It is a diagram. 1... Main piping, 2... Valve, 3... Branch pipe, 4...
・Valve, 5...Tank, 6...Internal fluid, 7...Air, 8...Valve, 9...Air pump, 11...Pressure detector, 12...Cable, 13 ...Air chamber, 1
4...Surge tank, 15...Check valve.

Claims (1)

[Claims] 1. In piping installed in power generation plants, etc., branch pipes are installed, and through valves that open at the same time as the main piping valve suddenly closes,
There are two layers: fluid and air inside the piping, and the internal pressure of the main piping is detected and the pressure is controlled based on that value. By connecting to the regulated tank, the pressure changes when the valve of the main piping closes suddenly. A hammering load relaxation method characterized by preventing the hammering load that occurs.