JPH07113445B2 - Leakage detection mechanism of double cutoff valve in gas combustion equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a leak detection mechanism of a double cutoff valve in a gas combustion device.

(Prior art and its problems) In gas combustion equipment, especially closed combustion equipment and box-type combustion equipment, if gas leaks and stays in the combustion chamber when combustion stops, 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. Further, in order to be safe even if it should leak, the combustion chamber is replaced (pre-purge) with new air every ignition.

However, this pre-purge is usually
For example, it takes 4 minutes or more to send in air, so it takes several minutes or more depending on the equipment, and therefore it takes too long from the ignition operation to the actual ignition. There is a problem that it is cooled by air, and conditions suitable for cooking cannot be maintained.

In view of such a point, the present invention makes it possible to easily and reliably perform the presence / absence of leakage of the double shutoff valve,
The purpose is to eliminate the need for pre-purge every ignition.

(Means for Solving the Problems) The structure of the present invention for achieving the above-mentioned object will be described with reference to the drawings corresponding to the embodiments. In the double shutoff valve 1 having 1 and 1b, a pressure increasing means 2 and a pressure detecting means 3 capable of increasing the pressure higher than the gas supply pressure are connected between the shutoff valves 1a and 1b.

(Operation) In the above configuration, the shutoff valves 1a and 1b are closed and the burner 4
When the fire is extinguished, the booster 2 is operated to shut off the shutoff valve.
The space 5 between the 1a and 1b is pressurized to a predetermined pressure higher than the gas supply pressure. Then, if there is no leakage from the shutoff valves 1a and 1b, the pressure in the space 5 remains the pressure at the time of pressurization even if time elapses, but if there is leakage, it gradually decreases with the passage of time. For example, if there is a leak only in the shutoff valve 1a on the upstream side, the pressure in the space 5 will eventually drop to the gas supply pressure, and if there is a leak in the shutoff valve 1b, it will eventually drop to atmospheric pressure.

Therefore, the presence or absence of a change in the pressure in the space 5 after a lapse of time from the time of pressurization can be detected by the pressure detecting means 3, and the presence or absence of a leak in the shutoff valves 1a, 1b can be detected by the presence or absence of a decrease in pressure above a predetermined level. it can. Then, the presence or absence of leakage is detected before the ignition operation of the burner 4 next time, and the ignition operation is not performed if a leakage is detected, thereby preventing the risk of explosion due to leakage. be able to. Therefore, it is not necessary to pre-purge the inside of the combustion chamber 6 for each ignition.

(Example) Next, the Example of this invention is described. In the embodiment shown in FIG. 1, the pressure increasing means 2 and the pressure detecting means 3 are individually connected between the upstream and downstream shutoff valves 1a and 1b by the respective pipes 8 and 9. The pressure increasing means 2 is configured to displace the diaphragm 11 partitioning the inside of the body 10 against the return spring 13 by the actuator 12 to compress and pressurize the one chamber 13 connected to the pipe 8. Further, the pressure detection means 3 is
The pressure is set to an appropriate pressure that is lower than the pressure when boosting and higher than the gas supply, and is turned on and off.

In such a configuration, when the burner 4 is extinguished, the actuator 12 is operated and the diaphragm 11 pressurizes the space 5 through the pipe 8. In the space 5, for example, if the pressure is increased to about 100 to 200 mmH ₂ O higher than the gas supply pressure, the reverse pressure resistance of the general-purpose solenoid valve, about 500 mmH ₂ O will not be exceeded with a sufficient safety factor. That is, it is possible to use a general-purpose product that is easily obtained as the upstream side shutoff valve 1a. Then, the pressure detection means 3 is configured to turn on when the set pressure is a value which is lower than the pressure at the time of pressurization by, for example, about 50 mmH ₂ O, and turns off when the set pressure is lower than that.

Then, when the ignition operation of the burner 4 is performed next time, when the pressure detecting means 3 is ON, the predetermined ignition operation is performed without leakage, and when it is OFF, the ignition operation is performed without leakage and the ignition operation is not performed. The person performs a predetermined operation.

As described above, the presence or absence of leakage can be detected, and the booster 2 and the pressure detector 3 are individually connected to the shutoff valves 1a and 1a by the respective pipes 8 and 9.
In the case of the present embodiment in which the pipes are connected between 1b, it is possible to prevent the following malfunctions that may occur due to the configuration in which the common pipes are connected.

That is, in the case of the latter configuration, the shutoff valves 1a, 1
If the side b is clogged, the pressure to the pressure detecting means 3 is maintained in the boosted state even if the shutoff valves 1a and 1b leak, so there is a risk of misidentification as no leakage.
In the former configuration, when the pipe 8 of the pressure increasing means 2 is clogged (or the pressure increasing means 2 itself fails), the pressure detected by the pressure detecting means 3 is not applied, so that it can be detected as an abnormality. At the same time, when the pipe 9 of the pressure detecting means 3 is clogged, the boosted pressure is not applied or the boosted state is maintained even after the operation of the pressure boosting means 2 is stopped, depending on the time of clogging. A phenomenon such as that occurs occurs, and it can be detected as an abnormality. The latter phenomenon is also caused by the failure of the pressure detection means 3 itself, but these phenomena are easily detected as abnormal in the course of a series of sequences from the operation of the boosting means 2 to the predetermined ignition operation. can do.

The above-mentioned components, that is, the booster 2 and the pressure detector 3
The specific configuration of the double shutoff valve 1 is also appropriate, and the double shutoff valve 1 has a configuration in which the individual shutoff valves 1a and 1b are connected by piping, and
A configuration in which parts a and 1b are integrated is appropriate.

The pressure in the space 5 changes due to the temperature change of the gas in the space 5 as well as the leakage, but this change is usually small and substantially affects the leakage detection operation of the present invention for the following reasons. Does not affect the target. That is, the misidentification of leakage may occur when the gas in the space 5 is cooled and the pressure drops, but normally, the shutoff valve is higher than the temperature of the supply gas.
1a, 1b and piping, because the ambient temperature of these is higher, the gas in the space 5 is heated rather than cooled, and the pressure rises, so there is no misperception, and even if it happens, on the safe side Since it is a motion, there is no problem.

(Effects of the Invention) As described above, the present invention is a dual shutoff valve having upstream and downstream shutoff valves, and between these shutoff valves, a pressure increasing means capable of increasing the pressure higher than the gas supply pressure, and a pressure Since the detection means is connected, the shut-off valves are closed, and the space between them is increased to a pressure higher than the gas supply pressure.
Leakage of any shutoff valve can be detected depending on the presence or absence of the pressure drop. By performing such detection during ignition operation and performing a predetermined operation according to the result, it is difficult to leak. Even if a leak occurs in the double shutoff valve, there is an effect that the danger of explosion can be surely prevented. Therefore, in the gas combustion equipment such as the closed combustion equipment and the box combustion equipment to which the present invention is applied, there is an effect that the pre-purge for each ignition can be omitted.

[Brief description of drawings]

FIG. 1 is a system explanatory diagram of the overall configuration corresponding to one embodiment of the present invention. Reference numeral 1 ... Double shutoff valve, 1a, 1b ... Shutoff valve, 2 ... Boosting means, 3 ... Pressure detecting means, 4 ... Burner, 5 ... Space, 6 ... Combustion chamber, 7 ... Fan , 8,9 …… Piping, 10…
… Body, 11 …… Diaphragm, 12 …… Actuator,
13 ... Return spring.

Claims (2)

[Claims] 1. A dual shutoff valve having upstream and downstream shutoff valves, wherein a pressure booster capable of boosting pressure higher than a gas supply pressure and a pressure detector are connected between the shutoff valves. Leakage detection mechanism of double cutoff valve in characteristic gas combustion equipment 2. The gas combustion device according to claim 1, wherein the pressure increasing means and the pressure detecting means are individually connected between the upstream side and the downstream side shutoff valves by respective pipes. Leakage Detection Mechanism of Double Shut-off Valve in Japan