JP4919725B2 - Vibration prevention method in gas piping system - Google Patents

Description

The present invention relates to a vibration preventing method for a gas pipe used in a gas pipe system for supplying city gas to a power plant using city gas, for example.

Conventionally, since natural gas consumers are mainly small-end customers, the supply piping line is generally supplied from a high-pressure conduit to a large number of small-end customers via a medium-pressure conduit network.
However, in recent years, due to deregulation of energy use, it has become possible for specific consumers to generate power themselves, and thus large consumers with power plants are increasing. There has been a demand for such large-volume customers to supply directly from the high-voltage main line near the customer to the customer without going through the medium-pressure conduit network.

In the case of supplying gas directly to the consumer from the high-pressure trunk line, for example, a self-powered pressure reducing valve is provided between the high-pressure trunk line and a specific consumer-side gas piping line.
In this case, since the change in the usage amount in a specific consumer is directly transmitted to the self-reducing pressure reducing valve, vibration may occur in the piping system due to the change. Such a vibration mechanism of the piping system is difficult to quantitatively grasp because the pressure pulsation of the fluid caused by the throttle element of the self-reducing pressure reducing valve and the natural period and rigidity of the piping system are complicatedly related. .
In addition, the fluctuation range, rate of change, etc. of the usage amount differ from customer to customer, and it is difficult to take vibration prevention measures in general.
Further, the occurrence of vibrations in the gas piping system is not limited to the above example, but occurs due to various factors.

As such a piping system vibration preventing apparatus, the following has been proposed.
The vibration generated in the pipe is detected by a vibration detector, and an excitation signal that cancels the vibration generated in the pipe is obtained by the operation controller using the detected signal, and vibration is generated in response to the vibration signal. A pipe vibration preventing device configured to prevent vibration of the pipe with a vessel (see Patent Document 1).
JP-A-5-141585

  However, the apparatus described in Patent Document 1 requires equipment such as a vibration detector, an arithmetic controller, and a vibration generator, and the control system is complicated, so that the apparatus is expensive.

The present invention has been made to solve such problems, and an object of the present invention is to obtain a vibration preventing method that can be handled for each consumer by simple means in a gas piping system.

A vibration prevention method in a gas piping system according to the present invention includes a high-pressure side gas piping that supplies city gas, a self-pressure reducing valve that depressurizes high-pressure gas supplied through the high-pressure side gas piping, It is a vibration preventing method in a gas piping system comprising a gas piping after decompression that is provided on the downstream side and supplies decompressed gas to a consumer side,
A plurality of capacity elements connected to the post-decompression gas pipe so as to communicate with each other, and an on-off valve that opens and closes communication between each capacity element and the post-decompression gas pipe. provided, wherein when the vibration occurs in the gas piping system, so as to communicate the most appropriate number the decompression after gas piping capacity elements for suppressing vibration of the piping system by opening and closing the on-off valve It is characterized by that.

In the present invention, a plurality of capacity elements connected so as to be able to communicate with the gas pipe after decompression, and between the capacity elements and the gas pipe after decompression, the communication between each capacity element and the gas pipe after decompression is opened and closed. An on-off valve that provides the most appropriate number of capacity elements and the post-decompression gas pipe to open and close the on-off valve to suppress vibration of the pipe system when vibration occurs in the gas pipe system. Because I tried to communicate
By selecting the number of capacitative elements that allow gas to flow according to the pressure pulsation and natural frequency of the piping system, it is possible to prevent vibration by changing the pressure pulsation and natural frequency of the piping system. The vibration prevention for each consumer can be realized by an extremely simple means without any restrictions.

[Embodiment 1]
FIG. 1 is an explanatory view of a gas piping system including a vibration preventing apparatus according to an embodiment of the present invention. The gas piping system in FIG. 1 is a gas supply line that supplies city gas to consumers. The illustrated portion is a connection between a high-pressure side gas piping that is a high-pressure side trunk line of city gas and a gas piping after decompression on the customer side. It is a piping line.

The piping line shown in FIG. 1 is a high-pressure side gas piping 1 that is a high-pressure side trunk line of city gas, a filter 3 provided in the high-pressure side gas piping 1, and a high-pressure gas that is provided downstream of the filter 3 to depressurize the high-pressure gas. A self-reducing pressure reducing valve 5, and a post-decompression gas pipe 9 for supplying a decompressed gas provided downstream of the self-powering pressure reducing valve 5 to a customer side 7 having a gas turbine, a gas engine, and other devices, It has.
The vibration preventing device 11 according to the present embodiment includes four tanks 13 corresponding to a plurality of capacity elements connected to the post-depressurized gas pipe 9 so as to communicate with each other, and each tank 13 and the post-depressurized gas distribution. There is an on-off valve 15 that opens and closes communication between the tank 13 and the gas pipe 9 after decompression.
Hereinafter, each configuration will be described in detail.

<Self-powered pressure reducing valve>
The self-reducing pressure reducing valve 5 adjusts the gas pressure on the high pressure side to a preset pressure by introducing the pressure on the downstream side into the actuator and adjusting the opening degree by itself using a diaphragm and a spring. It is a pressure reducing valve.

<Tank>
The tank 13 corresponds to a capacity element of the present invention, and each tank 13 communicates with the gas pipe 9 after decompression through a pipe 17. The communication between each tank 13 and the post-depressurized gas pipe 9 is controlled by an on-off valve 15.
The number of tanks 13 as capacity elements is not limited to four, and the capacity of each tank may be different.
Further, the capacity element of the present invention is not limited to a tank type like the tank 13, and may be a pipe as long as it has a certain capacity.

<Open / close valve>
The on-off valve 15 opens and closes communication between each tank 13 and the gas pipe 9 after decompression. The on-off valve 15 is basically a manual valve, but may be an automatic valve using an actuator.

The operation of the vibration preventing device 11 configured as described above will be described.
The high-pressure city gas supplied from the high-pressure side main line is reduced to the set pressure by the self-reducing pressure reducing valve 5, supplied to the gas pipe 9 after the pressure reduction, and used for each device on the customer side 7. When the gas flow rate changes depending on the usage state of each device on the customer side 7, the self-powered pressure reducing valve 5 adjusts the valve opening degree according to the pressure fluctuation after the pressure reduction, and the pressure of the gas pipe 9 after the pressure reduction. Adjust so that becomes the set pressure.

When the flow rate on the customer side 7 changes abruptly, the self-reducing pressure reducing valve 5 repeatedly opens and closes in a short time to follow this change, and pulsation occurs in the gas in the pipe. If it matches the natural frequency of the piping system, the vibration is amplified by resonance.
Therefore, when such a situation occurs, by opening the on-off valve 15 provided in the pipe 17, the pressure pulsation and the natural frequency of the pipe system are changed to suppress the vibration. In this example, since four tanks 13 are provided, the most appropriate number of tanks among the four tanks 13 for suppressing vibration of the piping system and the decompressed gas pipes 9 are communicated. That is, when vibration is generated, first, one on-off valve 15 is opened and the state is observed. If vibration is not suppressed, one on-off valve 15 is further opened and the state is observed. The number of tanks 13 having a high vibration suppressing effect are connected to the gas pipe 9 after decompression.

As described above, according to the present embodiment, the vibration of the piping system caused by the operation of the self-reducing pressure reducing valve 5 when the gas usage amount on the customer side 7 changes abruptly is extremely simple. It can be suppressed by the device.
In the above-described embodiment, the vibration generation source is exemplified by the one caused by the operation of the self-reducing pressure reducing valve 5 based on the rapid change of the gas usage amount on the customer side 7. Needless to say, the vibration preventing device 11 can be applied to other vibration sources and has the same vibration suppressing effect.

[Embodiment 2]
As described in the first embodiment, a self-reducing pressure reducing valve 5 is attached to a gas supply line for supplying city gas directly from a high-pressure gas pipe 1 of a high-pressure backbone to a specific large-volume consumer for pressure adjustment. A facility equipped with such a self-reducing pressure reducing valve 5 is called a governor station.
In such a governor station, as described in the first embodiment, when the pressure is adjusted by the self-reducing pressure reducing valve 5, vibrations due to the operation of the self-reducing pressure reducing valve 5 may occur.
Therefore, in the present embodiment, by using the vibration preventing device 11 shown in the first embodiment together with the self-powered pressure reducing valve 5, a pressure adjusting device having a function capable of suppressing vibrations for various consumers is provided. It is to provide.

FIG. 2 is an explanatory diagram of the pressure adjusting device according to the second embodiment, and FIG. 3 is a diagram showing a state seen from the direction of arrow A in FIG. In addition, the same code | symbol is attached | subjected to the apparatus same as the apparatus shown in FIG.
The pressure adjusting device according to the present embodiment includes a high-pressure side flange 19 for connection to a high-pressure gas pipe, an automatic opening / closing valve 21, an actuator 23 for the automatic opening / closing valve 21, a filter 3, a self-reducing pressure reducing valve 5, an opening / closing valve 25, A post-decompression flange 27 for connection to the customer side piping and four tanks 13 connected to the post-decompression line are provided.
A pair of the automatic opening / closing valve 21, the actuator 23 of the automatic opening / closing valve 21, the filter 3, the self-powered pressure reducing valve 5, and the opening / closing valve 25 are provided, and are used as normal and spare.

  The connection layout of each of these devices is as follows. The pipe 29 is raised upward from the high-pressure side flange, the inlet side of the filter 3 is connected to the upper end of the pipe 29, the pipe 31 is extended in the horizontal direction from the outlet side of the filter 3, and the inlet side enters the tip of the pipe 31. And attach an angle flow type self-reducing pressure reducing valve 5 whose exit side is a right angle. The post-decompression gas pipe 9 is connected with the outlet side of the self-powered pressure reducing valve 5 down, and a post-depressurization flange 27 is provided at the end of the post-depressurization gas pipe 9 to connect to the customer side line. The four tanks 13 are arranged in a space surrounded by the filter 3 and the horizontal portion of the gas pipe 9 after decompression, as shown in FIGS.

The pressure adjusting device having the above-described components and having the piping layout and unitized as described above is housed in one box as a governor station.
By adopting the piping layout as described above, the planar space of the governor station can be dramatically reduced as compared with the conventional case.

The pressure regulator configured as described above is installed in a gas supply line that supplies city gas to a specific large-volume consumer. In the following, the installation of the pressure adjusting device and the vibration preventing function by this will be described.
The high-pressure side gas pipe 1 is connected to the high-pressure side flange 19 in the pressure adjusting device, and the customer-side pipe is connected to the flange 27 after decompression. Then, the set pressure of the self-reducing pressure reducing valve 5 is set to the demand pressure of the customer.

  When the setting of the self-pressure reducing valve 5 is completed as described above, the high-pressure gas of the high-pressure side main line is supplied to the post-decompression gas pipe 9 via the self-powered pressure reducing valve 5 and is adjusted to the gas usage situation of the consumer. Perform a test run to demonstrate the vibration prevention function. That is, the usage state of the consumer is observed, and for example, it is confirmed whether or not vibration occurs when there is a sudden change in the gas usage amount on the consumer side. When the piping system vibrates due to the use situation of the customer due to the use situation of the customer, the on-off valve 15 provided between the tank 13 and the decompressed gas pipe 9 is opened. As a result, the pressure pulsation and natural frequency of the piping system are changed. And about the said consumer, it confirms how many tanks of the four tanks 13 are connected with the low voltage | pressure side gas piping 9, and the vibration prevention effect is the highest. And the tank of the number with the highest vibration prevention effect and the gas piping 9 after pressure reduction are connected.

As described above, according to the present embodiment, it is possible to achieve vibration prevention with a simple configuration in accordance with the usage state of each customer side.
The number of tanks 13 is not limited to four, and may be one, two, three, five or more. Moreover, it is not limited to a tank type like the tank 13, but may be a pipe.

It is explanatory drawing of the vibration prevention apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the piping layout of the vibration preventing apparatus which concerns on one embodiment of this invention. It is explanatory drawing seen from the arrow A direction of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure side gas piping 3 Filter 5 Self-powered pressure reducing valve 7 Customer side 9 Low pressure side gas piping 11 Vibration prevention device 13 Tank 15 On-off valve 17 Piping

Claims (1)

A high-pressure side gas pipe for supplying city gas, a self-powered pressure reducing valve for reducing the pressure of the high-pressure gas supplied through the high-pressure side gas pipe, and a gas provided at a downstream side of the self-powered pressure reducing valve A vibration prevention method in a gas piping system comprising a post-decompression gas piping to be supplied to the side,
A plurality of capacity elements connected to the post-decompression gas pipe so as to communicate with each other, and an on-off valve that opens and closes communication between each capacity element and the post-decompression gas pipe. provided, wherein when the vibration occurs in the gas piping system, so as to communicate the most appropriate number the decompression after gas piping capacity elements for suppressing vibration of the piping system by opening and closing the on-off valve A method for preventing vibrations in a gas piping system.

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