JPH11351444A - Gas control valve leak inspection method and apparatus - Google Patents

Abstract

(57) [Summary] [Problem] To perform an accurate leak test of a gas control valve in a short time. SOLUTION: A first gas control valve 21 to a fourth gas control valve 24 are sequentially opened one by one, and a flow meter 26 detects a gas flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting leakage of a gas control valve.

[0002]

_2. Description of the Related Art In combustion devices and the like, at present, CO2 reduction and energy saving are called for. As a major premise of safe ignition, pre-purge is performed to remove gas remaining in a combustion chamber or the like before starting combustion. This pre-purge is performed the same number of times as the start and stop of the burner, and reaches up to 20 times / h in the reflux boiler. Since cold outside air is introduced into the combustion chamber, the reduction in thermal efficiency is said to reach as much as 2%, which causes a decrease in steam pressure and a decrease in steam dryness during the pre-purge.

Therefore, in recent years, there has been a tendency to review the pre-purge operation. If the leakage of a gas control valve interposed between a gas supply source and a combustion chamber is within a limit, combustion is started without pre-purge. There is a movement to make it. Under such a background, an important issue is how to quickly and accurately inspect the gas control valve for leakage. Japanese Patent Laying-Open No. 2-180392 discloses a method of inspecting a gas control valve for leakage using gas pressure.

FIG. 7 is a view showing such a conventional gas control valve leak inspection apparatus. In FIG. 7, reference numeral 1 denotes a first gas control valve, 2 denotes a second gas control valve, and 3 denotes a gas line. 4, a pressure detection switch that is turned on when a predetermined gas pressure is reached,
5 is a controller.

Next, the operation will be described. First, the set pressure at which the pressure detection switch 4 is turned on is set to half of the gas inlet pressure P1, and in a state where the first gas control valve 1 and the second gas control valve 2 are closed, The second gas control valve 2 is opened for a short time. At this time, if the pressure detection switch 4 is not turned on within a predetermined time, it is determined that there is no leak in the first gas control valve 1.

Next, the first gas control valve 1 is opened for a short time. At this time, it is determined that there is no leakage in the second gas control valve 2 unless the pressure detection switch 4 is turned off. And
If there is no leak in both the first gas control valve 1 and the second gas control valve 2, normal combustion operation is started, and if there is any leak, the combustion operation is stopped.

[0007]

Since the conventional gas control valve leak inspection apparatus is constructed as described above, it takes time until the gas pressure drops due to the leak of the gas control valve. Takes 1-2 minutes. In a steam boiler or the like, when this leak inspection device is used in a combustion gas piping system, the steam pressure is reduced during this inspection time, and wasteful heat is generated.

[0008] Further, since the leakage of the gas control valve is checked by using the pressure as an alternative characteristic, the supply pressure fluctuates depending on the location, time and the like, and accurate confirmation cannot be performed. JP-A-2-18
Although Japanese Patent No. 0392 proposes a method for shortening the check time, there is a limit to an inspection method using pressure. The conventional gas control valve leak inspection apparatus has a problem that must be solved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a gas control valve leak inspection method and apparatus capable of performing an accurate leak inspection in a short time. I do.

[0010]

According to the gas control valve leakage inspection method of the present invention, each gas control valve is controlled so as to stop the flow of gas flowing from the gas supply side to the downstream side. The leak of each gas control valve is inspected by detecting the flow of gas in the flow path surrounded by the valve.

[0011] A gas control valve leak inspection device according to the present invention includes a first branch flow path and a second branch flow path branched from a main flow path on a gas supply side, and an intervening member in the first branch flow path. A first gas control valve and a second gas control valve downstream thereof,
Leakage of the gas control valve for inspecting a leak of each of the gas control valves in a system including a third gas control valve interposed in the second branch flow path and a fourth gas control valve downstream of the third gas control valve. In the inspection device, a communication pipe for connecting between the first gas control valve and the second gas control valve, and between a third gas control valve and a fourth gas control valve, and an intervening part in the communication pipe Flow detecting means for detecting the flow of gas that has been performed; valve control means for controlling so as to sequentially open only one of the first to fourth gas control valves; When the gas flow is detected by the flow inspection means when the fourth gas control valve is opened, it is determined that the first gas control valve has a leak, and the third gas control valve is opened. Sometimes, when the flow of gas is detected by the flow inspection means, the gas leaks to the second gas control valve. Determines that, when the flow of gas is detected by the flow checking means when opening the second gas control valve, it is determined that there is a leak in the third gas control valve,
When a flow of gas is detected by the flow inspection means when the first gas control valve is opened, a judgment means for judging that the fourth gas control valve has a leak is provided.

According to the present invention, there is provided a gas control valve leak inspection device comprising: a first gas control valve interposed in a main flow path on a gas supply side; a second gas control valve downstream of the first gas control valve; A branch passage branched from an upstream side of the gas control valve and connected between the first gas control valve and the second gas control valve, and a third gas control valve interposed in the branch passage In the gas control valve leak inspection device for inspecting the leak of each of the gas control valves of the system having the above, the gas flow amount of the gas is detected by being interposed in the branch flow path downstream of the third gas control valve. First, only the third gas control valve is opened, then the third gas control valve is closed, and the second gas control valve is opened, and the pressure is applied to the upstream and downstream sides of the first gas control valve. Valve control for closing the second gas control valve after providing the difference and opening only the third gas control valve again Determining the stage, the first time the flow of gas is detected by the flow detecting means when opening the third gas control valve is leaking in the second gas control valve, a third
When the gas flow control valve is opened again and the gas flow rate attenuation is larger than the flow rate attenuation when the first gas control valve does not leak, it is determined that the first gas control valve has a leak. And determination means for performing the determination.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. 1 is a view showing the configuration of a gas control valve leak inspection device according to Embodiment 1 of the present invention. In FIG. A branch flow path (first branch flow path) for sending gas to a main burner (not shown), and a branch for feeding gas to a pilot burner (not shown) by branching from the main flow path 10. This is a flow path (second branch flow path).

Reference numeral 21 denotes a first gas control valve interposed in the branch flow path 11, and reference numeral 22 denotes a second gas control valve interposed downstream of the first gas control valve 21 in the branch flow path 11. Valve, 23
Is a third gas control valve interposed in the branch flow passage 12, and 24 is a fourth gas control valve interposed downstream of the third gas control valve 23 in the branch flow passage 12. Channels 11 and 12
Are provided with two gas control valves, respectively, to double shut off the gas to ensure safety. In such a gas control valve system, reference numeral 25 denotes each gas control valve 21.
, A communication pipe connecting between the first gas control valve 21 and the second gas control valve 22 and between the third gas control valve 23 and the fourth gas control valve 24 to check for leaks , 26 are flow meters (flow detecting means) for detecting gas flow in both directions,
Reference numeral 27 denotes each gas control valve 21 according to the flowchart of FIG.
To 24 (opening and closing) to execute a leak inspection.

FIG. 2 shows a flow meter 2 used in the first embodiment.
FIG. 2 is a cross-sectional view showing the configuration of FIG. 6. In FIG. 2, 31 is a main body block of the flow meter 26, 32 and 33 are pipe mounting flanges, 34 and 35 are O-rings, and 36 and 37 are pipe mounting flanges 32 and 33, respectively. Pipes attached to, 38
Is an upper plate screwed to the main body block 31 with screws 39 and 40, 41 is a flow path formed by a groove having a rectangular cross section on the upper surface of the main body block 31, 42 and 43 are rectifying wire meshes interposed in the flow path 41, 44 is a microflow sensor chip, 45 is a substrate on which the microflow sensor chip 44 is mounted, 46 is a bracket for fixing the substrate 45, and 47 is a lead for outputting a detection signal detected by the microflow sensor chip 44 to a detection circuit. Line. For example, when a flow sensor having a fine diaphragm structure disclosed by the present applicant in Japanese Patent Application Laid-Open No. 4-230808 is used as the above-mentioned micro flow sensor chip, the flow velocity (flow rate) can be measured with high accuracy and high speed response. it can.

Next, the operation of the leak control device for a gas control valve according to the first embodiment will be described with reference to the flowchart of FIG. In step ST1, the first gas control valve 2
1 (described as "V1" in the figure), the second gas control valve 22 (described as "V2" in the figure), and the third gas control valve 23 (described as "V3" in the figure). ) And the fourth gas control valve 24 (denoted as “V4” in the figure) to stop the gas flow.

Since the pressure on the gas supply side is higher than the pressure on the burner side, when there is a leak in the fourth gas control valve 24, gas flows through the flow meter 26. Therefore,
By controlling the opening and closing of the gas control valves 21 to 24 in this way, it is possible to inspect the fourth gas control valve 24 for leakage. In step ST2, the gas flow rate is detected by the flow meter 26, and it is determined whether the gas flow rate is within the allowable value.

If the flow rate is equal to or less than the allowable value, it is determined that there is no leak in the fourth gas control valve 24, and the process proceeds to step ST3. In step ST3, the second gas control valve 22 is opened and the first gas control valve 21, the third gas control valve 23, and the fourth gas control valve are checked to check for leakage of the third gas control valve 23. Close 24.

In step ST4, the flow rate of the gas is detected by the flow meter 26, and it is determined whether or not the gas flow rate is within the allowable value. Is determined to have no leakage, and the process proceeds to step ST5.

In step ST5, the second gas control valve 2
In order to check for a leak of 2, the third gas control valve 23 is opened, and the first gas control valve 21, the second gas control valve 22, and the fourth gas control valve 24 are closed.

In step ST6, the flow rate of the gas is detected by the flow meter 26, and it is determined whether or not the gas flow rate is within the allowable value.
Proceed to T7.

In step ST7, the first gas control valve 2
In order to check for a leak, the fourth gas control valve 24 is opened, and the first gas control valve 21, the second gas control valve 22, and the third gas control valve 23 are closed.

In step ST8, the flow rate of the gas is detected by the flow meter 26, and it is determined whether the gas flow rate is within the allowable value. If the gas flow rate is equal to or less than the allowable value, the first gas control valve 21 It is determined that there is no leak in all the gas control valves from to the fourth gas control valve 24, and the inspection ends.

Next, in step ST2, when the gas flow rate exceeds the allowable value, the fourth gas control valve 24
Is determined to have a leak. Similarly, in step ST4, when the gas flow rate exceeds the allowable value, it is determined that there is a leak in the third gas control valve 23. In step ST6, when the gas flow rate exceeds the allowable value, , Second
It is determined that there is a leak in the gas control valve 22 of step ST.
In 8, when the gas flow exceeds the allowable value,
It is determined that the first gas control valve 21 has a leak, and
If it is determined that there is a leak, the process proceeds to step ST9 to output a warning or stop the burner operation.

As described above, according to the first embodiment, the opening and closing of each gas control valve 21 to 24 is controlled to detect whether or not there is a gas flow. Since the leak is inspected, an effect that an accurate leak inspection of the gas control valve can be performed is obtained.

Further, since the instantaneous flow is detected by the flow meter 26, a leak test can be performed in a short time. For this reason, when such a gas control valve leak inspection device is used in a combustion system of a boiler, the effect that heat loss during a test time can be extremely reduced can be obtained.

Embodiment 2 In FIG. 4, reference numeral 50 denotes a main passage, and two gas control valves are provided in the main passage 50 for safety as in the first embodiment.
Are a first gas control valve and a second gas control valve according to the second embodiment provided in the main flow path 50, respectively. In such a gas control valve system, reference numeral 51 denotes a first gas control valve 61, a branch flow path provided for inspecting a leak of the second gas control valve 62, 63 denotes a third gas control valve,
Reference numeral 64 denotes a flow meter (flow detection means), and 65 denotes a controller (valve control means, determination means) for controlling the opening and closing of each of the gas control valves 61 to 63 in accordance with the flowchart of FIG. The flow meter 64 has the same configuration as that of the first embodiment shown in FIG.

Next, the operation of the gas control valve leakage inspection device according to the second embodiment will be described with reference to the flowchart of FIG. In step ST11, the third gas control valve 63 (shown as “V3” in the figure) is opened, the first gas control valve 61 (shown as “V1” in the figure), and the second gas control valve. 62 (indicated as "V2" in the figure) is closed.

Since the pressure on the gas supply side is higher than the pressure on the burner side, if there is a leak in the second gas control valve 62, the gas flows via the flow meter 64, so that the second gas control valve 62 leaks can be detected.

In step ST12, the flow rate of the gas is detected by the flow meter 64, and it is determined whether or not the flow rate of the gas is within an allowable value. If the flow rate of the gas is within the allowable value, it is determined that there is no leak in the second gas control valve 62, and step ST1 is performed.
Proceed to 3.

In step ST13, a preparation for an inspection for leakage of the first gas control valve 61 is made. First gas control valve 61
Then, the third gas control valve 63 is closed, the second gas control valve 62 is opened for a short time, and then closed again. Since the pressure on the burner side is lower than that on the upstream side of the second gas control valve 62, the first gas control valve 61 and the second gas control valve can be opened only by opening the second gas control valve 62 for a short time. The pressure between the valve and the valve 62 is released by a predetermined amount.

In step ST14, the third gas control valve 63 is opened while the first gas control valve 61 and the second gas control valve 62 are closed.

Since the pressure on the gas supply side is higher than the pressure in the pipe surrounded by V1, V2 and V3, gas flows from V3 into this pipe. At this time, as shown in FIG. 6, the flow rate attenuation differs depending on whether or not the first gas control valve 61 leaks. That is, when there is a leak in the first gas control valve 61, the gas flows into the pipe from V1 immediately after the end of ST13, and the gas pressure in the pipe increases, so that the differential pressure on both sides of V1 decreases. Therefore, the flow rate decreases in a short time as compared with the case where there is no leakage. The presence or absence of leakage of the first gas control valve 61 can be determined based on this flow rate attenuation characteristic.

In order to determine whether or not the flow rate is rapidly attenuated, a predetermined threshold value Vth is set in advance to the flow rate after a lapse of a predetermined time t after execution of step ST14. The flow rate measured later may be compared with the threshold value Vth. Alternatively, the time required to reach Vth may be measured and compared.

In step ST15, it is determined whether or not the flow rate decay is fast. When the flow rate measured after the lapse of the predetermined time t exceeds the threshold value Vth, the flow rate attenuation is small,
It is determined that the first gas control valve 61 has no leakage. First
When it is determined that there is no leakage in the gas control valve 61 and the second gas control valve 62, the burner is ignited without prepurge.

Next, in step ST12, when the gas flow rate exceeds the allowable value, the second gas control valve 62
Is determined to have a leak, and in step ST15, when it is determined that the gas flow rate after the elapse of the predetermined time t is equal to or less than the threshold value Vth and the gas flow rate is rapidly attenuated, the first gas control valve 61 It is determined that there is a leak, and both steps S
Proceed to T16.

In step ST16, since there is a leak in the first gas control valve 61 or the second gas control valve 62, processing such as outputting an alarm or stopping the operation of the burner is executed.

As described above, according to the second embodiment, the first gas control valve 6 is controlled while observing the attenuation of the gas flow rate.
By judging the leakage of the first and second gas control valves 62, it is possible to obtain an effect that an accurate gas control valve leakage test can be performed quickly even in such a gas control valve system. In the first and second embodiments, it is optimal to use a flow rate sensor having a fine diaphragm structure as the flow detecting means, but it is also possible to use other flow sensors or flow switches depending on conditions. .

[0039]

As described above, according to the present invention, it is possible to perform an accurate leak test of a gas control valve, and to detect an instantaneous flow by the flow detecting means. The effect that can be performed is obtained. For this reason, when such a gas control valve leak inspection method is used in a combustion system of a boiler, there is an effect that heat loss during a test time can be extremely reduced.

According to the present invention, the first branch flow path and the second branch flow path branched from the main flow path on the gas supply side, and the first gas control device interposed in the first branch flow path A system comprising a valve and a second gas control valve downstream thereof, and a third gas control valve interposed in the second branch flow path and a fourth gas control valve downstream thereof. The leak test of the gas control valve can be performed accurately, and the effect that the leak test can be performed in a short time can be obtained. Therefore, when such a gas control valve leak inspection device is used in a combustion system of a boiler, there is an effect that heat loss during a test time can be extremely reduced.

According to the present invention, the first gas control valve interposed in the main flow path on the gas supply side, the second gas control valve downstream of the first gas control valve, and the first gas control valve from the upstream side of the first gas control valve Also in a system including a branch flow path branched and connected between the first gas control valve and the second gas control valve, and a third gas control valve interposed in the branch flow path. It is possible to perform an accurate leak test of the gas control valve, and an effect that the leak test can be performed in a short time is obtained.When such a leak control device of the gas control valve is used for a combustion system of a boiler, There is an effect that heat loss during the test time can be extremely reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a gas control valve leak inspection device according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a configuration of the flow meter of FIG.

FIG. 3 is a flowchart showing the operation of the gas control valve leak inspection device according to Embodiment 1 of the present invention.

FIG. 4 is a block diagram showing a configuration of a gas control valve leakage inspection device according to Embodiment 2 of the present invention.

FIG. 5 is a flowchart showing an operation of the gas control valve leakage inspection device according to Embodiment 2 of the present invention.

FIG. 6 is an explanatory diagram showing a flow rate attenuation of the flow meter of FIG. 4;

FIG. 7 is a block diagram showing a configuration of a conventional gas control valve leak inspection device.

[Explanation of symbols]

 10, 50 main flow path 11 branch flow path (first branch flow path) 12 branch flow path (second branch flow path) 21, 61 first gas control valve 22, 62 second gas control valve 23, 63 Third gas control valve 24 Fourth gas control valve 25 Communication pipe 26, 64 Flow meter (flow detection means) 27, 65 Controller (valve control means, determination means) 51 Branch flow path

Continued on the front page (72) Inventor Masao Moroboshi 2-12-19 Shibuya, Shibuya-ku, Tokyo Inside Yamatake Ha Newel Co., Ltd.

Claims (3)

[Claims] 1. A method for inspecting a leakage of a gas control valve provided at least three or more in a flow path of a gas flowing from a gas supply side to a downstream side, wherein each gas control valve is configured to stop the flow of the gas. Control the
A gas control valve leakage inspection method, wherein a gas flow in a flow path surrounded by each gas control valve is detected to inspect each gas control valve for leakage. 2. A first branch flow path and a second branch flow path branched from a main flow path on a gas supply side, a first gas control valve interposed in the first branch flow path, and a downstream thereof. Gas control valves of a system comprising a second gas control valve on the side, a third gas control valve interposed in the second branch flow path, and a fourth gas control valve on the downstream side thereof A leak inspection device for a gas control valve for inspecting a leak of a gas, wherein a connection is made between the first gas control valve and the second gas control valve, and between a third gas control valve and a fourth gas control valve. A communication pipe; a flow detection means interposed in the communication pipe to detect a gas flow; and sequentially providing only one of the first to fourth gas control valves. Valve control means for controlling the valve to open; predetermined gas control based on the relationship between the operated control valve and the detection result of the flow detection means. Leak test apparatus of the gas control valve, characterized in that a determination means that there is a leak in the valve. 3. A first gas control valve interposed in a main flow path on a gas supply side, a second gas control valve downstream of the first gas control valve, and a second gas control valve branched from an upstream side of the first gas control valve. A branch flow path connected between the first gas control valve and the second gas control valve,
In a gas control valve leak inspection device for inspecting a leak of each gas control valve of a system including a third gas control valve interposed in the branch flow path, a downstream side of the third gas control valve Flow detecting means interposed in the branch flow path for detecting the gas flow rate; first, only the third gas control valve is opened, then the third gas control valve is closed, and the second gas control valve is opened. Valve control means for controlling a pressure difference between the upstream side and the downstream side of the first gas control valve to close the second gas control valve and open only the third gas control valve again; Determining means for determining that a predetermined gas control valve has a leak based on the relationship between the control valve and the flow detection result.