JPH01147215A - Leak inspection for double isolation valve in gas combustion equipment - Google Patents

Abstract

PURPOSE:To make it possible to perform, for sure at all times the inspection of an isolation valve for the leak in it by performing setting of pressure setting means after a specified time has passed from the motion of closing the isolation valve. CONSTITUTION:The setting for a pressure setting device 2 which is provided between isolation valves 1a and 1b on the upstream side and downstream side respectively is performed after a specified time length has passed from closing the isolation valves 1a and 1b. When the fire of a burner 5 is to be extinguished, the isolation valves 1a and 1b are closed, and then after a specified time length has passed, the pressure setting device 2 is operated and the pressure in the space 4 between the isolation valves 1a and 1b is set at pressure which is different from the pressure in supplying gas. When there is a gas leak in either of the valves 1a and 1b, the gas pressure in the space 4 rises or falls with the elapse of time. Accordingly, by detecting the pressure in the space 4 after a specified time has passed from operating the pressure setting device 2 by a pressure detection device 3, it is possible to detect the presence of leak in the isolation valves 1a and 1b by judging if there is a change of pressure more than specified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting leakage of a double shutoff valve in gas combustion equipment.

(Conventional technology and its problems) In gas combustion equipment, especially closed combustion equipment and box-type combustion equipment, if gas leaks and remains in the combustion chamber when combustion is stopped, there is a risk of explosion at the next ignition. is high. Therefore, in these devices, a double shutoff valve having upstream and downstream shutoff valves is used in the fuel gas supply system to prevent leakage as much as possible. Furthermore, to ensure safety even in the event of a leak, the combustion chamber is replaced with fresh air (pre-purge) every time it is ignited during temperature control.

However, this pre-purge usually reduces the internal volume of the combustion chamber.
For example, it takes more than a few minutes depending on the device because more than four times as much air is pumped in, so it takes too much time from the ignition operation to the actual ignition, and with open adjustment devices, the room may be purged. There is a problem in that the food is cooled by the air, making it impossible to maintain conditions suitable for cooking.

The present invention has been devised in view of this point, and includes a pressure setting means and a pressure detection means between the upstream and downstream shutoff valves, and when the shutoff valve is in the closed state, the pressure between the shutoff valves is The pressure is set to a predetermined pressure different from the gas supply pressure by the pressure setting means, and the temporal change in the pressure is detected by the pressure detection means to easily detect the presence or absence of leakage of the double shutoff valve.
The purpose of the present invention is to eliminate the need for pre-purge every time ignition by ensuring that the pressure setting means is operated in a rational manner. The purpose of this is to enable even more reliable detection.

(Means for Solving the Problems) The method of the present invention for achieving the above object will be explained based on the figures corresponding to the embodiments. First, the first invention is as follows.
Upstream and downstream shutoff valves 1a.

A pressure setting means 2 and a pressure detection means 3 are installed between 1b.
In the open state of the cutoff valves 1a and 1b, the cutoff valve 1a
, Ib is set to a predetermined pressure different from the gas supply pressure by the pressure setting means 2, and the pressure detecting means 3 detects a temporal change in the pressure to detect a leak, The setting operation of the pressure setting means 2 is the cutoff valve 1a.

The gist of this is to perform this after a predetermined period of time has elapsed since the closing operation of 1b.

Further, the second invention provides 1-stream side and downstream side shutoff valves 1a, I
A pressure setting means 2 and a pressure detecting means 3 are provided between the cutoff valves 1a and 1b, and when the cutoff valves 1a and 1b are in the closed state, the cutoff valves 1a and 1b are
In the method of detecting a leak by setting the pressure between the points b to a predetermined pressure different from the gas supply pressure by the pressure setting means 2 and detecting the temporal change in the pressure by the pressure detecting means 3, The setting operation of the pressure setting means 2 is performed after a predetermined period of time has elapsed from the closing operation of the cutoff valves 1a and 1b, and
The setting release operation of the pressure setting means 2 is performed by the shutoff valve 1a,
A predetermined period of time before the opening operation of the shutoff valves 1a,
Prior to the opening operation of the pressure detecting means 1b, the pressure detecting means 3 is inspected based on the change in the pressure detected by the pressure detecting means 3.

In such a configuration, the pressure setting means 2 includes the cutoff valves Ia and l.
If the configuration allows the pressure between the valves 1a and 1a to be set to a predetermined pressure different from the gas supply pressure, it is possible to use a pressurized configuration, that is, the shutoff valves 1a and 1a.
The space 4 between b may be configured to be pressurized to a predetermined pressure higher than the gas supply pressure, or conversely may be reduced to a predetermined pressure lower than atmospheric pressure.

(Operation) Next, the operation of the present invention will be explained based on the drawings corresponding to the embodiments.

First, in the first invention, when the cutoff valves 1a and 1b are closed to extinguish the burner 5, the pressure is set after a predetermined time (for example, about 1 second) after the cutoff valves 1a and 1b are closed. The means 2 is operated to set the pressure in the space 4 between the shutoff valves ia and 1b to a predetermined pressure different from the gas supply pressure. That is, when the pressurizing type pressure setting means 2 is applied, the pressure in the space 4 is increased to a pressure P2 higher than the gas supply pressure P1, as shown in FIG. is a pressure P2' lower than atmospheric pressure P4 as shown in Figure 2(b).
Reduce the pressure to

However, if there is no leakage from the shutoff valves 1a and 1b, the pressure in the space 4 will remain as shown in Figs. 2(a) and 2(b) even if time passes.
), the pressure at the time of setting P2. P2'
However, if there is any leakage, it gradually decreases or increases as time passes, as shown by the broken lines. For example, if there is a leak only in the upstream cutoff valve 1a, the pressure in the space 4 will eventually change to the gas supply pressure P1, and if there is a leak only in the cutoff valve 1b, the pressure in the space 4 will finally change to the atmospheric pressure P4.

Therefore, the pressure in the space 4 after a predetermined time has elapsed since the operation of the pressure setting means 2 is detected by the pressure detection means 3, and it is determined whether or not the pressure has changed by more than a predetermined value, that is, the pressure in the space 4 is determined to be the set pressure P2. The judgment pressure changes from P2' to P3. By determining whether or not P3' has been exceeded, it is possible to detect the presence or absence of leakage from the cutoff valves 1a and 1b.

In this way, the detection of the presence or absence of the above leakage will be performed next time.
By configuring the system so that the ignition operation is performed before starting the ignition operation, and the ignition operation is not performed once a leak is detected, it is possible to reliably prevent the risk of explosion due to an unexpected leak. Therefore, there is no need to pre-purge the combustion chamber 6 every time ignition occurs.

By the way, due to their structure, the shutoff valves 1a and 1b do not completely close at the moment of the closing operation, and it takes some time (for example, less than 1 second) to completely close them.

For this reason, the shutoff valve 1a.

If the closing operation of the shutoff valve 1b and the pressure setting operation of the pressure setting means 2 are performed at the same time, the pressure in the space 4 will not be stabilized due to the influence of the transition state of the shutoff valves 1a and lb, and as shown in FIGS. As shown by the two-dot chain line, there are cases where the determination pressure P3°P3' is not reached, and in this case, leakage cannot be detected normally.

However, as described above, in the first invention, the setting operation of the pressure saw setting means 2 is performed a predetermined time after the closing operation of the cutoff valves 1a and 1b, so that the cutoff valves 1a and Ib are completely closed. Since the pressure in the space 4 is increased or decreased after this, the pressure in the space 4 stably reaches a predetermined pressure, and thus leakage can be normally detected at all times.

Next, the second invention is similar to the first invention in that the setting operation of the pressure setting means 2 is performed after a predetermined time has elapsed from the closing operation of the shutoff valves 1a and 1b, but in addition, the pressure setting The setting release operation of the means 2 is performed a predetermined time before the opening operation of the cutoff valves 1a and 1b.

When the shutoff valves 1a and 1b are not leaking, when the setting release operation of the pressure setting means 2 is performed in this way, the pressure in the space 4 becomes the set pressure P2. P2' to judgment pressure P3. P3'
, and returns to the pressure before the setting operation, that is, the gas supply pressure P1. Note that Figures 3 (a) and (b) show cases where there is a minute leak that does not need to be detected; in this case, the pressure in the space 4 is due to a pressure change due to the minute leak. The gas supply pressure P1 decreases or increases by the same amount as the gas supply pressure P1.

When the setting release operation of the pressure setting means 2 is performed as described above,
When the pressure detection means 3 is operating normally, the pressure detected by the pressure detection means 3 also changes in accordance with changes in the pressure in the space 4. However, in the pressure detection means 3, abnormalities may occur, such as sticking of contacts when a contact is used for the detection output of l1ii leakage or abnormal output due to residual strain in the pressure detection unit body. In this case, the detected pressure does not follow changes in the pressure in the space 4. Therefore, when the setting release operation of the pressure setting means 2 is performed, the pressure detection means 3
Based on the detected pressure change, it is possible to check whether the pressure detection means 3 is operating normally. Through such an inspection, it is possible to confirm the validity of the detection output indicating the presence or absence of leakage detected by the pressure detection means 3 before the setting cancellation operation.

As mentioned above, this effectiveness is confirmed using the shutoff valve 1a.

Since this is performed before the opening operation of the shutoff valve 1b, even if the absence of leakage is output before the setting cancellation operation, if an abnormality in the pressure detection means 3 is detected by the setting cancellation operation, the subsequent shutoff valve ia , 1b is not opened, it is possible to reliably prevent the occurrence of danger in the case where a leak exists but the pressure detection means 3 cannot detect it due to its own failure. can.

(Example) Next, the present invention will be explained in detail. In the embodiment shown in FIG. 1, the pressure setting means 2 and the pressure detecting means 3 are connected between the shutoff valves 1a and Ib by pipes 7 and 8, respectively. Pressure setting means 2
indicates a pressurized type, in which a diaphragm 10 that partitions the inside of the vessel body 9 is moved a predetermined distance upward in the figure against a return spring 12 by the operation of an actuator 11, and a chamber 13 to which the piping 7 is connected is moved. is compressed, thus shutoff valve 1a
, 1b, and by stopping the operation of the actuator 11, the diaphragm 10 is returned to its original position by the return spring 12, and the pressure increase is released. The container body 9, diaphragm 10, actuator 11 and return spring 12 as described above
It is easy to construct the reduced pressure type pressure setting means 2 using the above. Further, the pressure detection means 3 detects that the gas supply pressure P1 is lower than the predetermined pressure P2 set by the pressure setting means 2.
The configuration is such that a pressure P3 higher than that is used as the determination pressure to turn ON-OFF. In such a configuration, when the next time the burner 5 is ignited, if the pressure detection means 3 is OFF, there is a leakage and control is shifted to a predetermined process, and the O
In the case of N, the leakage point is output, and when the setting of the pressure setting means 2 is canceled prior to the opening operation of the shutoff valves 1a and 1b as described above, the pressure detection means 3 becomes 0-
In the case of FF, the pressure detection means 3 is abnormal and the predetermined burner 5 is closed with the opening operation of the cutoff valves 1a and 1b.
If the ignition operation continues and the pressure detection means 3 remains in the ON state, the pressure detection means 3 determines that there is an abnormality and opens the shutoff valves 1a and Ib regardless of the previous leakage and no output. The ignition operation of the burner 5 is stopped and control is shifted to a predetermined process. In this way, dangers due to leakage can be reliably prevented. It goes without saying that the above-described operation of the pressure detection means 3 and the processing thereof can be performed in the same manner even when the pressure reduction type pressure setting means 2 is applied.

(Effects of the Invention) As described above, the present invention provides a pressure setting means and a pressure detection means between the upstream and downstream shutoff valves. The pressure is set to a predetermined pressure different from the gas supply pressure by the pressure setting means, and the temporal change in the pressure is detected by the pressure detection means, so that the presence or absence of leakage from the double shutoff valve can be detected. In particular, it is possible to eliminate the need for pre-purge every time ignition occurs during temperature control, but in particular, the first invention sets the pressure between the shutoff valves by the pressure setting means, Since it can be carried out stably at all times up to a predetermined pressure, there is an effect that normal leakage detection can be carried out at all times.The second invention adds a special device in addition to the effects of the first invention. The pressure detection means can be inspected without any failure, and this has the effect of reliably preventing the occurrence of danger in the event that there is a leakage that cannot be detected due to a failure of the pressure detection means itself. In the first invention, the pressure detection means can be inspected by adding a special device, etc. Thus, the present invention can detect the presence or absence of leakage from the double shutoff valve. By being able to perform the detection reliably, there is an effect that there is no need for pre-purge every time ignition occurs during temperature control, and problems caused by pre-purge can be solved.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram of the overall configuration corresponding to an embodiment of the gas combustion equipment to which the present invention is applied, FIGS. 2(a) and (b) are explanatory diagrams showing the operation of the first invention, and FIG. (aL, (b) are explanatory diagrams showing the main parts of the operation of the second invention. Reference numerals 1a, 1b...Shutoff valves, 2...Pressure setting means,
3... Pressure detection means, 4... Space, 5... Burner, 6... Combustion chamber, 7.8... Piping, 9... Vessel body,
10...Diaphragm, 11...Actuator,
12... Return spring, 13... Pressure chamber, 14... Fan.

Claims (2)

[Claims] (1) A pressure setting means and a pressure detection means are provided between the upstream and downstream shutoff valves, and when the shutoff valve is in a closed state, the pressure between the shutoff valves is set to the gas supply pressure by the pressure setting means. In the method of detecting a leak by setting different predetermined pressures and detecting a temporal change in the pressure by the pressure detection means, the setting operation of the pressure setting means is changed from the closing operation of the shutoff valve to the predetermined value. A method for detecting leakage from a double shutoff valve in gas combustion equipment, which is characterized by detecting leakage after a period of time has elapsed. (2) A pressure setting means and a pressure detection means are provided between the upstream and downstream shutoff valves, and when the shutoff valve is in a closed state, the pressure between the shutoff valves is set to the gas supply pressure by the pressure setting means. In the method of detecting a leak by setting different predetermined pressures and detecting a temporal change in the pressure by the pressure detection means, the setting operation of the pressure setting means is changed from the closing operation of the shutoff valve to the predetermined value. The setting release operation of the pressure setting means is performed after a predetermined period of time has elapsed, and the setting release operation of the pressure setting means is performed a predetermined time before the opening operation of the cutoff valve, and the pressure is A method for detecting leakage from a double shutoff valve in gas combustion equipment, characterized by inspecting the detection means.