JP2012181078A - Cutoff valve leakage detection method and liquid mixture prevention method using the same - Google Patents

Abstract

Leakage shut-off in a piping system that selectively supplies any one type of fluid to the downstream side by opening and closing a shut-off valve without mixing a plurality of types of fluids individually supplied from the upstream side Provided are a shutoff valve leakage detection method capable of accurately detecting a valve, and a fluid mixing prevention method capable of appropriately preventing fluid mixing using the same.
A plurality of shut-off valves (31) to (36) are installed in the supply pipes (11) to (13) of each fluid (1) to (3) up to a junction where the respective fluid supply pipes (11) to (13) join together. The pressure detectors 51 to 57 are installed on the upstream side and the downstream side of each of .about.36, and the pressure waveforms detected by the pressure detectors 51 to 57 are compared, so that any of the shutoff valves 31 to 36 can be compared. A method for detecting a shut-off valve, characterized by detecting whether there is a leak.
[Selection] Figure 1

Description

  According to the present invention, leakage detection of a shutoff valve in a piping system that selectively supplies any one type of fluid to the downstream side by opening and closing the shutoff valve without mixing a plurality of types of fluids individually supplied from the upstream side. The present invention relates to a method and a fluid mixing prevention method using the method.

  In a piping system that selectively supplies any one type of fluid to the downstream side without mixing a plurality of types of fluids that are individually supplied from the upstream side, in addition to the selected fluid for quality and safety reasons. It is necessary to prevent this fluid from being mixed and supplied downstream.

  For example, in a converter blowing gas supply facility equipped with a piping system that selects either high-purity Ar gas or crude Ar gas used in the converter blowing process and supplies it to the converter, A plurality of shut-off valves are provided in each gas supply pipe up to a junction where a high-purity Ar gas supply pipe for supplying high-purity Ar gas and a crude Ar gas supply pipe for supplying crude Ar gas are joined. A blow pipe is connected between the pipes, and a blow valve is provided in the middle of the blow pipe, and when all the shutoff valves of any of the supply pipes are closed, By opening the blow valve provided in the middle of the blow piping connected between the shut-off valves, it is possible to prevent other gases from being mixed into the gas that is selectively supplied to the converter. (See Patent Document 1).

JP 2005-264259 A

  However, as in Patent Document 1, a plurality of shutoff valves are provided in each fluid supply pipe up to a junction where a plurality of types of fluid supply pipes merge, and a blow pipe is connected between the shutoff valves. For a blower connected between a plurality of shut-off valves in the supply pipe when a blow-off valve is provided in the middle of the blow pipe and all the shut-off valves in each supply pipe are closed. In the method of preventing fluid mixture by opening the blow valve provided in the middle of the piping, even if the front and rear shut-off valves at the location where the blow pipe is connected leaks, Since it is impossible to determine whether or not there is a leak, it is necessary to check whether or not each shut-off valve is leaking when replacing the leaking shut-off valve. In addition, when multiple shutoff valves for each supply pipe are closed, the fluid flowing through the supply pipe must be discharged outside the system, and there are leaks in the shutoff valves before and after the location where the blow pipe is connected. In this case, the fluid flowing through the supply pipe is discharged out of the system until the leaked shut-off valve is replaced.

  The present invention has been made in view of the above circumstances, and selectively selects one of the fluids by opening and closing the shut-off valve without mixing a plurality of fluids individually supplied from the upstream side. In a piping system supplied downstream, a leak detection method for a shut-off valve that can accurately detect a leaking shut-off valve, and fluid mixture prevention that can appropriately prevent fluid mixture using the same It is intended to provide a method.

  In order to solve the above problems, the present invention has the following features.

  [1] In a piping system that supplies any one type of fluid to the downstream side without mixing a plurality of types of fluids that are individually supplied from the upstream side, up to the junction where each fluid supply piping joins A plurality of shut-off valves are installed in series in each fluid supply pipe, and pressure detectors are installed on the upstream side and the downstream side of each of the plurality of shut-off valves, and the pressure waveforms detected by these pressure detectors A shutoff valve detection method characterized by detecting which shutoff valve leaks by comparing.

  [2] A fluid mixing prevention method using the leakage detection method for a shut-off valve according to [1], wherein a blow-off is provided between a plurality of shut-off valves installed in each fluid supply pipe up to the junction. Connecting the piping for piping, providing a blow valve in the middle of the piping for blowing, providing a blowing valve downstream of the blowing valve, and releasing the pressure upstream of the shutoff valve upstream from the position where the piping for blowing is connected. And the pressure on the downstream side of the shutoff valve on the downstream side from the position where the blow piping is connected, and leak from all of the shutoff valves installed in any of the fluid supply pipes. If it is detected that the fluid is detected, the blow valve provided in the supply pipe is opened, and the fluid is discharged from the supply pipe to the outside of the system.

[3] A converter blowing gas supply facility to which the leakage detection method for a shut-off valve according to [1] or the fluid mixing prevention method according to [2] is applied, wherein the plurality of types of fluids are high purity Ar gas and whether the two fluids of high purity N ₂ gas, or converter, which is a three fluid high purity Ar gas and high-purity N ₂ gas and the low-purity Ar gas Blowing gas supply equipment.

  In the shut-off valve detection method of the present invention, it is possible to accurately detect which shut-off valve is leaking. Therefore, as described above, since the method described in Patent Document 1 cannot identify which shut-off valve is leaking, when the leaking shut-off valve is replaced, the presence or absence of leakage of each shut-off valve is confirmed. However, it is not necessary in the present invention, and the leaking shut-off valve can be quickly replaced.

  Further, in the fluid mixing prevention method of the present invention, the blower provided in the supply pipe is only detected when leakage is detected from all of the plurality of shut-off valves installed in any of the fluid supply pipes. Since the valve is opened and the fluid is discharged from the supply pipe to the outside of the system, the cost is reasonable.

It is a figure which shows the piping system in one Embodiment of this invention. In one Embodiment of this invention, when each cutoff valve is favorable, it is a figure which shows the pressure waveform detected with each pressure detector. In one Embodiment of this invention, it is a figure which shows the pressure waveform detected with each pressure detector, when there exists a leak in the 3rd cutoff valve. In one Embodiment of this invention, it is a figure which shows the pressure waveform detected with each pressure detector, when there is a leak in the 4th cutoff valve. In one Embodiment of this invention, it is a figure which shows the pressure waveform detected with each pressure detector, when there is a leak in the 3rd cutoff valve and the 4th cutoff valve.

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

  Here, three types of fluids (first fluid, second fluid, and third fluid) are individually supplied from the upstream side, and any of these three types of fluids is not mixed and is opened or closed by opening and closing the shut-off valve. In a piping system that supplies one type of fluid to the downstream side, a method for detecting the presence or absence of leakage of the shut-off valve when the first fluid is supplied to the downstream side and the second fluid and the third fluid are shut off A method for preventing the mixing of fluid based on the detection result will be described.

  FIG. 1 is a diagram showing a piping system in one embodiment of the present invention. In FIG. 1, the flow of various fluids is indicated by solid lines, and the flow of various signals is indicated by broken lines.

  As shown in FIG. 1, in the piping system in this embodiment, a first supply pipe 11 that supplies the first fluid 1 from the upstream side and a second supply that supplies the second fluid 2 from the upstream side. A pipe 12 and a third supply pipe 13 for supplying the third fluid 3 from the upstream side are arranged, and the first supply pipe 11 has a first cutoff for blocking the first fluid 1. A valve 31 and a second shut-off valve 32 are installed in series, and a third shut-off valve 33 and a fourth shut-off valve 34 for shutting off the second fluid 2 are connected in series to the second supply pipe 12. In the third supply pipe 13, a fifth cutoff valve 35 and a sixth cutoff valve 36 for blocking the third fluid 3 are installed in series. The first supply pipe 11 to the third supply pipe 13 are connected to the supply pipe 14, and any one of the first fluid 1 to the third fluid 3 is opened and closed by opening and closing the shut-off valves 31 to 36. The fluid is supplied to the downstream side via the supply pipe 14.

  A first blow pipe 21 for discharging the first fluid 1 out of the system is connected to the first supply pipe 11 between the first shut-off valve 31 and the second shut-off valve 32. The first blow pipe 21 is provided with a seventh shut-off valve 37 and a first blow valve 41. Similarly, a second blow pipe 22 for discharging the second fluid 2 out of the system is connected to the second supply pipe 12 between the third shut-off valve 33 and the fourth shut-off valve 34. An eighth shut-off valve 38 and a second blow valve 42 are disposed in the second blow pipe 22. Similarly, a third blow pipe 23 for releasing the third fluid 3 to the outside of the system is connected to the third supply pipe 13 between the fifth cutoff valve 35 and the sixth cutoff valve 36. A ninth shut-off valve 39 and a third blow valve 43 are arranged in the third blow pipe 23.

  The first pressure detector 51 that detects the pressure upstream of the first shut-off valve 31 in the first supply pipe 11 and the pressure between the first shut-off valve 31 and the second shut-off valve 32 are set. A second pressure detector 52 for detecting, a third pressure detector 53 for detecting the pressure upstream of the third shut-off valve 33 in the second supply pipe 12, a third shut-off valve 33 and a fourth shut-off valve A fourth pressure detector 54 for detecting the pressure between the shut-off valves 34, a fifth pressure detector 55 for detecting the pressure upstream of the fifth shut-off valve 35 in the third supply pipe 13, A sixth pressure detector 56 for detecting the pressure between the fifth cutoff valve 35 and the sixth cutoff valve 36; a seventh pressure detector 57 for detecting the pressure in the fourth supply pipe 14; The pressure waveforms from the first pressure detector 51 to the seventh pressure detector 57 are taken in, and the seventh shutoff valve 37 to the ninth shutoff valve. And the arithmetic and control unit 61 which outputs a closing operation signal of the valve 39 is disposed.

  Then, as presupposed here, when the first fluid 1 is selectively supplied to the fourth pipe 14, the first cutoff valve 31 and the second cutoff valve 32 are opened, and the third The shutoff valve 33 to the sixth shutoff valve 36 are closed. The seventh cutoff valve 37 to the ninth cutoff valve 39 are also closed.

  At that time, when the shutoff valves 31 to 39 are all good, the pressure waveforms output from the pressure detectors 51 to 57 are as shown in FIG. That is, the pressure waveform of the first pressure detector 51 becomes a waveform having a pressure fluctuation controlled by the supply source of the first fluid 1, and the pressure waveform of the second pressure detector 52 through which the pressure waveform propagates The pressure waveform of the seventh pressure detector 57 is also a pressure waveform similar to the pressure waveform of the first pressure detector 51. Further, the pressure waveform of the third pressure detector 53 is a pressure waveform having a pressure fluctuation controlled by the supply source of the second fluid 2, and the pressure of the fourth pressure detector 54 that does not propagate any pressure waveform. The waveform is a pressure waveform without pressure fluctuation. The pressure waveform of the fifth pressure detector 55 becomes a pressure waveform having a pressure fluctuation controlled by the third fluid 3 supply source, and the pressure of the sixth pressure detector 56 does not propagate any pressure waveform. The waveform is a pressure waveform without pressure fluctuation.

  On the other hand, when there is leakage in the third shutoff valve 33 and the other shutoff valves are good, the pressure waveforms output from the pressure detectors 51 to 57 are as shown in FIG. That is, the pressure waveform upstream of the third shut-off valve 33 is propagated downstream of the third shut-off valve 33, so that the third pressure detector located upstream of the third shut-off valve 33 is used. The pressure waveform of 53 and the pressure waveform of the fourth pressure detector 54 located on the downstream side of the third shut-off valve 33 become a pressure waveform having similar pressure fluctuations. The pressure waveforms other than the fourth pressure detector 54 are the same as those described with reference to FIG.

  In addition, when there is leakage in the fourth shut-off valve 34 and other shut-off valves are good, the pressure waveforms output from the pressure detectors 51 to 57 are as shown in FIG. That is, the pressure waveform on the downstream side of the fourth shut-off valve 34 is propagated to the upstream side of the fourth shut-off valve 34, so the seventh pressure detector located on the downstream side of the fourth shut-off valve 34. The pressure waveform of 57 and the pressure waveform of the fourth pressure detector 54 located on the upstream side of the fourth shut-off valve 34 are similar to each other. The pressure waveforms other than the fourth pressure detector 54 are the same as those described with reference to FIG.

  In addition, when there is leakage in the third shutoff valve 33 and the fourth shutoff valve 34 and the other shutoff valves are good, the pressure waveforms output from the pressure detectors 51 to 57 are as shown in FIG. become. That is, the pressure waveform on the upstream side of the third cutoff valve 33 is propagated downstream of the third cutoff valve 33, and the pressure waveform on the downstream side of the fourth cutoff valve 34 is the fourth cutoff valve. 34, the pressure waveform of the fourth pressure detector 54 located on the downstream side of the third cutoff valve 33 and on the upstream side of the fourth cutoff valve 34 is the third waveform. A pressure waveform obtained by combining the pressure waveform of the third pressure detector 53 located on the upstream side of the shutoff valve 33 and the pressure waveform of the seventh pressure detector 57 located on the downstream side of the fourth shutoff valve 34; Become. Therefore, the pressure waveform of the fourth pressure detector 54 is a pressure waveform that is not similar to either the pressure waveform of the third pressure detector 53 or the pressure waveform of the seventh pressure detector 57. Note that the pressure waveforms other than the fourth pressure detector 54 are the same as those described with reference to FIG.

  From the above, the presence or absence of leakage of the third cutoff valve 33 and the fourth cutoff valve 34 can be detected as follows.

  (1) First, when the pressure waveform of the fourth pressure detector 54 is a pressure waveform without pressure fluctuation, it is determined that neither the third shut-off valve 33 nor the fourth shut-off valve 34 is leaking. it can.

  However, if the pressure waveform of the fourth pressure detector 54 is a pressure waveform with pressure fluctuation, either one or both of the third shut-off valve 33 and the fourth shut-off valve 34 are leaking. become. Therefore, the determination is made according to the following (2) to (4).

  (2) When the pressure waveform of the fourth pressure detector 54 is similar to the pressure waveform of the third pressure detector 53, it can be determined that only the third shut-off valve 33 is leaking. .

  (3) If the pressure waveform of the fourth pressure detector 54 is similar to the pressure waveform of the seventh pressure detector 57, it can be determined that only the fourth shut-off valve 34 is leaking. .

  (4) When the pressure waveform of the fourth pressure detector 54 is a pressure waveform that is not similar to either the pressure waveform of the third pressure detector 53 or the pressure waveform of the seventh pressure detector 57, It can be determined that both the third cutoff valve 33 and the fourth cutoff valve 34 are leaking.

  As described above, the pressure waveform of the seventh pressure detector 57 is similar to the pressure waveform of the first pressure detector 51 and the pressure waveform of the second pressure detector 52. ), (4), the pressure waveform of the first pressure detector 51 or the pressure waveform of the second pressure detector 52 may be used instead of the pressure waveform of the seventh pressure detector 57.

  In the above description, the case where the presence / absence of leakage of the third cutoff valve 33 and the fourth cutoff valve 34 is detected is described. However, the presence / absence of leakage of the fifth cutoff valve 35 and the sixth cutoff valve 36 is detected. In this case, if the third shut-off valve 33 is replaced with the fifth shut-off valve 35 and the fourth shut-off valve 34 is replaced with the sixth shut-off valve 36 in the above, the presence or absence of leakage is similarly detected. be able to.

  By the way, in the above, when determining whether two pressure waveforms are similar or not similar, the two pressure waveforms are overlapped, the difference in amplitude is calculated at a predetermined time pitch, and the difference in amplitude is determined in advance. If the accumulated value is equal to or less than the predetermined value, the two pressure waveforms are determined to be similar, and if the integrated value exceeds the predetermined value, the two pressure waveforms are not similar. Is determined.

  Next, a method for preventing the mixing of fluid based on the detection result of the leakage of the shut-off valve described above will be described.

  First, as described in (2) above, when it is detected that only the third shut-off valve 33 is leaking, the fourth shut-off valve 34 is not leaking. The fluid 2 is not supplied to the downstream side via the supply pipe 14 in a state where the fluid 2 is mixed. Further, as described in (3) above, when it is detected that only the fourth shutoff valve 34 is leaking, the third shutoff valve 33 is not leaking. The fluid 2 is not supplied to the downstream side via the supply pipe 14 in a state where the fluid 2 is mixed. Therefore, in any case, it is sufficient to replace the shut-off valve (the third shut-off valve 33 or the fourth shut-off valve 34) detected as leaking at an appropriate time.

  On the other hand, when it is detected that both the third shut-off valve 33 and the fourth shut-off valve 34 are leaking as described in (4) above, the first fluid 1 is left as it is. Since the second fluid 2 is mixed and supplied to the downstream side via the supply pipe 14, the eighth cutoff valve 38 is immediately opened, and the third cutoff valve 33 and the fourth cutoff valve are opened. From the second blow valve 42, which is adjusted so that the pressure between the valves 34 is lower than the pressure upstream of the third shut-off valve 33 and the pressure downstream of the fourth shut-off valve 34, The second fluid 2 leaking from the third shut-off valve 33 and the first fluid 1 leaking from the fourth shut-off valve 34 and backflowed are discharged out of the system. This prevents the second fluid 2 from being mixed with the first fluid 1 and supplied to the downstream side.

  Thus, it is rational in terms of cost by discharging the minimum necessary fluid out of the system.

  In the above description, the case where the third shut-off valve 33 or / and the fourth shut-off valve 34 that shuts off the second fluid 2 has leaked is described, but the fifth fluid shuts off the third fluid 3. The same applies when there is a leak in the shutoff valve 35 and / or the sixth shutoff valve 36.

  In the above description, the second fluid 2 and the third fluid 3 are shut off and the first fluid 1 is supplied to the downstream side. However, the first fluid 1 and the third fluid 3 are described. The same applies to the case where the second fluid 2 is supplied downstream and the first fluid 1 and the second fluid 2 are shut off and the third fluid 3 is supplied downstream. Thus, leakage of the shutoff valve can be detected and fluid can be prevented from being mixed.

  In addition, the above-described method for detecting leakage of the shutoff valve and the method for preventing fluid mixing include a check valve installed between the installation position of the second shutoff valve 32 and the connection position to the fourth supply pipe 14. A check valve is installed between the installation position of the fourth cutoff valve 34 and the connection position to the fourth supply pipe 14, and between the installation position of the sixth cutoff valve 36 and the connection position to the supply pipe 14. The same can be applied to a piping system provided with a check valve.

  Furthermore, in this embodiment, the case where three types of fluids are individually supplied from the upstream side has been described. However, when two types of fluids are individually supplied from the upstream side, or four or more types are individually supplied from the upstream side. Even in the case where the fluid is supplied, the same operation can be performed.

Then, the above-described leakage detection method for the shut-off valve and the fluid mixing prevention method are applied to the converter blowing gas supply equipment at the steel works, and two kinds of gases, high purity Ar gas and high purity N ₂ gas, are introduced from the upstream side. When the leaked shut-off valve is replaced when individually supplying three types of gases, ie, high purity Ar gas, high purity N ₂ gas and low purity Ar gas, from the upstream side This makes it possible to reduce the amount of blow of high-purity Ar gas and low-purity Ar gas, which are rare and expensive, and is rational in terms of cost.

DESCRIPTION OF SYMBOLS 1 1st fluid 2 2nd fluid 3 3rd fluid 11 1st supply piping 12 2nd supply piping 13 3rd supply piping 14 4th supply piping 21 1st blow piping 22 2nd Blow pipe 23 Third blow pipe 31 First shut-off valve 32 Second shut-off valve 33 Third shut-off valve 34 Fourth shut-off valve 35 Fifth shut-off valve 36 Sixth shut-off valve 37 Seventh shut-off valve Shut-off valve 38 Eighth shut-off valve 39 Ninth shut-off valve 41 First blow valve 42 Second blow valve 43 Third blow valve 51 First pressure detector 52 Second pressure detector 53 Third Pressure detector 54 Fourth pressure detector 55 Fifth pressure detector 56 Sixth pressure detector 57 Seventh pressure detector 61 Arithmetic control device

Claims (3)

  In a piping system that supplies any one type of fluid to the downstream side without mixing a plurality of types of fluids that are individually supplied from the upstream side, the flow of each fluid up to the merging point where each of the fluid supply pipings merges A plurality of shut-off valves are installed in series in the supply pipe, and pressure detectors are installed on the upstream side and the downstream side of each of the plurality of shut-off valves, and the pressure waveforms detected by these pressure detectors are compared. Thus, a shutoff valve detection method is characterized in that it detects which shutoff valve is leaking.   A fluid mixing prevention method using the shutoff valve leakage detection method according to claim 1, wherein a blow pipe is connected between a plurality of shutoff valves installed in each fluid supply pipe up to the junction. In addition, a blow valve is provided in the middle of the blow pipe, a blow valve is provided downstream of the blow valve, and the discharge pressure is increased by the upstream side of the shutoff valve upstream of the position where the blow pipe is connected and It should be set lower than the pressure on the downstream side of the shutoff valve on the downstream side from the position where the service pipe is connected, and leak from all of the shutoff valves installed in any fluid supply pipe. When detected, a fluid mixing prevention method characterized in that a blow valve provided in the supply pipe is opened and the fluid is discharged out of the system from the supply pipe. A gas supply equipment for converter blowing using the method for detecting leakage of a shut-off valve according to claim 1 or the method for preventing mixing of fluid according to claim 2, wherein the plurality of types of fluid are high-purity Ar gas and Two types of fluids of high-purity N ₂ gas, or three types of fluids of high-purity Ar gas, high-purity N ₂ gas, and low-purity Ar gas Facility.

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