JP2021124258A - Gas shutoff device - Google Patents

Abstract

To provide a shutoff device that can be designed by using a simpler configuration.SOLUTION: A gas shutoff device 100 includes: a first shutoff valve 51; a second shutoff valve 52 disposed downstream of the first shutoff valve 51; a connection passage 53 connecting the first shutoff valve 51 and the second shutoff valve 52; a pressure measurement section 54 measuring a pressure in the connection passage 53; and a control section 71 controlling the first shutoff valve 51 and the second shutoff valve 52. The control section 71 includes a leakage detection section 711 detecting gas leakage from the first shutoff valve 51. The leakage detection section 711 closes the second shutoff valve 52 after closing the first shutoff valve 51, and restricts an opening operation of the second shutoff valve 52 when the pressure measurement section 54 detects a pressure equal to or greater than predetermined pressure after the first shutoff valve 51 and the second shutoff valve 52 are closed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas shutoff device including a double shutoff valve.

Conventionally, a combustion device such as a boiler that heats supply water to generate steam by burning gaseous fuel has been used. Then, a technique has been proposed in which such a combustion device is configured to include a gas shutoff device having a double shutoff valve.

In such a gas shutoff device, the first shutoff valve and the second shutoff valve constituting the double shutoff valve can operate under a pressure corresponding to the maximum supply pressure of the fuel gas supplied to the combustion device. The diameter of the orifice that constitutes the shutoff valve and the size of the actuator that operates the shutoff valve are determined. Specifically, when designing a shutoff valve so that it can operate under high pressure, it is necessary to design the orifice diameter to be small or to use an actuator having a large driving force.

Here, if the diameter of the orifice is designed to be small in each of the two shutoff valves, the pressure loss in the gas shutoff device becomes large. Further, when an actuator having a large driving force is used, the size of the device increases and the manufacturing cost increases.

Therefore, a gas shutoff device including a bypass path connecting the primary side and the secondary side of the second shutoff valve arranged on the downstream side and a bypass valve arranged on the bypass path has been proposed (patented). Reference 1). According to the technique proposed in Patent Document 1, the pressure can be reduced by bypassing the gas on the primary side of the second shutoff valve through the bypass path at a predetermined timing, so that the second shutoff valve can be operated at a lower pressure. It is supposed to be.

JP-A-2019-39632

However, in the technique proposed in Patent Document 1, it is necessary to configure the gas shutoff device including a bypass path and a bypass valve, which complicates the device configuration.

Therefore, an object of the present invention is to provide a breaking device that can be designed with a simpler configuration.

In the present invention, the first shutoff valve, the second shutoff valve arranged on the downstream side of the first shutoff valve, the connection path connecting the first shutoff valve and the second shutoff valve, and the connection. A gas shutoff device including a pressure measuring unit for measuring pressure in a road and a control unit for controlling the first shutoff valve and the second shutoff valve. The control unit is the gas of the first shutoff valve. A leak detection unit for detecting a leak is provided, and the leak detection unit closes the second shutoff valve after closing the first shutoff valve, closes the first shutoff valve and the second shutoff valve, and then closes the second shutoff valve. The present invention relates to a gas shutoff device that limits the opening operation of the second shutoff valve when a pressure equal to or higher than a predetermined pressure is detected by the pressure measuring unit.

Further, when the control unit starts supplying gas, it is preferable that the first shutoff valve is opened after the second shutoff valve is opened.

Further, the leak detection unit temporarily opens the second shutoff valve when the pressure measurement unit does not detect a predetermined pressure increase within a predetermined time after closing the first shutoff valve. Is preferable.

Further, it is preferable that the gas shutoff device further includes a pressure release valve arranged in the connection path.

According to the present invention, it is possible to provide a breaking device that can be designed with a simpler configuration.

It is a figure which shows typically the boiler which includes the gas shut-off device which concerns on one Embodiment.

Hereinafter, a preferred embodiment of the gas shutoff device of the present invention will be described with reference to the drawings. In the present embodiment, the gas shutoff device is used by being incorporated in a boiler as a combustion device. FIG. 1 is a diagram schematically showing a boiler provided with a gas shutoff device.

The boiler 1 of the present embodiment is a steam boiler that heats water using gas as fuel to generate steam, and supplies steam to a load device (not shown).
The boiler 1 is discharged from the can body 10, the blower 20 that sends combustion air to the can body 10, the air supply duct 30 that connects the can body 10 and the blower 20, and the combustion air flows through, and the can body 10. The exhaust stack 80 through which the combustion gas (exhaust gas) flows, the fuel supply line 50 that supplies the fuel gas to the can body 10, the gas shutoff device 100 arranged in the fuel supply line 50, and the can body 10 are filled with water. A water supply line 60 for supplying and a control device 70 are provided.

The can body 10 includes a boiler housing 11, a plurality of water pipes 12, a lower header 13, an upper header 14, and a burner 15.

The boiler housing 11 constitutes the outer shape of the can body 10. An air supply port 16 is formed on one side surface of the boiler housing 11, and an exhaust port 17 is formed on a side surface facing the side surface on which the air supply port 16 is formed.

The plurality of water pipes 12 are arranged inside the boiler housing 11 so as to extend in the vertical direction, and are arranged at predetermined intervals in the longitudinal direction and the width direction of the boiler housing 11.

The lower header 13 is arranged at the lower part of the boiler housing 11. The lower ends of the plurality of water pipes 12 are connected to the lower header 13. The upper header 14 is arranged on the upper part of the boiler housing 11. The upper end portions of the plurality of water pipes 12 are connected to the upper header 14.

The burner 15 is arranged at the air supply port 16. The burner 15 burns the air-fuel mixture of the fuel gas and the combustion air, and the water in the water pipe 12 is heated to generate steam.

The blower 20 includes a fan, a blower main body 21 having a motor for rotating the fan, and an inverter 22 for increasing or decreasing the rotation speed of the fan (motor). The blower 20 sends combustion air to the can body 10 by rotating the fan at a predetermined rotation speed according to the frequency input to the inverter 22.

In the present embodiment, the flow rate of combustion air is set according to the required load required from the load device (not shown). The blower 20 is controlled by the control device 70 via the inverter 22 so as to have a set flow rate of fuel air.

The air supply duct 30 supplies the combustion air to be mixed with the fuel gas to the can body 10. The upstream end of the air supply duct 30 is connected to the blower 20, and the downstream end is connected to the air supply port 16. The air supply duct 30 supplies the combustion air sent from the blower 20 to the can body 10.
A damper 31 is arranged in the air supply duct 30.

The damper 31 is in a closed state in which the flow path of the combustion air inside the air supply duct 30 is closed, and is opened by rotating 90 degrees from this closed state to open the flow path of the combustion air inside the air supply duct 30. Arranged rotatably between states.

The exhaust pipe 80 is formed in a tubular shape with the base end side connected to the exhaust port 17. The combustion gas (exhaust gas) generated in the can body 10 is discharged to the outside of the can body 10 through the exhaust stack 80.

The upstream side of the fuel supply line 50 is connected to a fuel supply source (not shown), and the downstream side is connected to the air supply duct 30. The downstream end of the fuel supply line 50 is connected to the downstream side of the air supply duct 30 where the damper 31 is arranged. The fuel supply line 50 supplies fuel gas to the air supply duct 30.

The gas shutoff device 100 controls the supply and stop of the fuel gas flowing through the fuel supply line 50 to the can body 10. Further, the gas shutoff device 100 has a leak detection function for detecting a leak of fuel gas in the gas shutoff device 100. The details of the leak detection function will be described later.
The gas shutoff device 100 includes a first shutoff valve 51, a second shutoff valve 52, a connection path 53, a pressure sensor 54 as a pressure measuring unit, a pressure release valve 55, and a control device described later, which are arranged in the fuel supply line 50. It is configured to include a control unit 71 constituting the 70.

The first shutoff valve 51 is composed of an on-off valve such as a solenoid valve. The first shutoff valve 51 opens or closes the fuel supply line 50 to supply and stop the fuel gas.

The second shutoff valve 52 is composed of an on-off valve such as a solenoid valve. The second shutoff valve 52 is arranged on the downstream side of the first shutoff valve 51. The second shutoff valve 52 opens or closes the fuel supply line 50 to supply and stop the fuel gas.
The connection path 53 connects the first shutoff valve 51 and the second shutoff valve 52.

The pressure sensor 54 detects the pressure of the fuel gas flowing through the connecting path 53.
The first shutoff valve 51, the second shutoff valve 52, the connection path 53, and the pressure sensor 54 are integrally configured as a gas shutoff mechanism including a so-called double shutoff valve and are arranged in the fuel supply line 50.
The pressure release valve 55 is arranged in the connecting path 53. When the pressure inside the connecting path 53 exceeds the set pressure, the pressure release valve 55 releases the fuel gas inside the connecting path 53 to the outside. The operating pressure of the pressure release valve 55 is set higher than the pressure for determining gas leakage by the leak detection unit 711.

The water supply line 60 supplies water to the can body 10. The upstream side of the water supply line 60 is connected to a water supply source (not shown), and the downstream side is connected to the lower header 13. A water supply valve 61 is arranged on the water supply line 60.

Next, the control device 70 will be described. The control device 70 includes a control unit 71 that controls the combustion state of the boiler 1 and a storage unit 72 that stores various types of information.
The control device 70 is electrically connected to each of the above-mentioned sensors, and controls the first shutoff valve 51, the second shutoff valve 52, the blower 20, etc. based on the signals from these sensors and the requested load from the load device. This is performed to control the combustion state of the boiler 1. Further, the control device 70 adjusts the opening / closing or opening degree of the water supply valve 61 according to the combustion state of the boiler 1 to control the water level of the water pipe 12.

Further, the control unit 71 includes a leak detection unit 711 that determines whether or not there is a gas leak of fuel gas from the gas shutoff device 100 (so-called valve leakage) while the combustion of the boiler 1 is stopped (for example, after post-purging). ..

The operation of the leak detection unit 711 will be described.
The leak detection unit 711 stops the combustion of the boiler 1, for example, at the end of the post-purge performed to discharge the fuel gas remaining inside the can body 10 to the outside after the combustion is stopped, the gas shutoff device 100 (first shutoff). Leakage detection for determining leakage from the valve 51) is performed. In this case, the leak detection unit 711 first closes the first shutoff valve 51 and then closes the second shutoff valve 52. As a result, the secondary side of the fuel supply line 50 with respect to the first shutoff valve 51 communicates with the atmosphere via the can body 10. Therefore, the pressure on the secondary side of the first shutoff valve 51 in the fuel supply line 50 including the connection path 53 is lower than the gas pressure on the fuel supply source side of the first shutoff valve 51 (for example, equivalent to atmospheric pressure). Pressure).

Then, the leak detection unit 711 monitors the pressure detected by the pressure sensor 54 after closing the first shutoff valve 51 and the second shutoff valve 52, and detects a pressure equal to or higher than a predetermined pressure by the pressure sensor 54. In addition, it is determined that a valve leakage from the first shutoff valve 51 has occurred. The predetermined pressure is set to a value higher than the atmospheric pressure and smaller than the supply pressure of the fuel gas from the fuel supply source.
The leak detection unit 711 limits the opening operation of the second shutoff valve 52 when the pressure sensor 54 detects a pressure equal to or higher than a predetermined pressure. That is, when the leak detection unit 711 determines that a leak through the valve from the first shutoff valve 51 has occurred, the leak detection unit 711 prohibits the opening operation of the second shutoff valve 52.

As a result, the opening operation of the second shutoff valve 52 can be prohibited when a leak is detected in the first shutoff valve 51, and the pressure in the connection path 53 when no leak occurs in the first shutoff valve 51 is increased. It can be atmospheric pressure. Therefore, since the gas shutoff device 100 can be configured so that the second shutoff valve 52 is designed to correspond to the gas supply pressure lower than that of the first shutoff valve 51, the actuator that drives the second shutoff valve 52 can be miniaturized, and the manufacturing cost can be reduced. The gas shutoff device 100 can be manufactured with a simple configuration while reducing the cost. Further, by designing the second shutoff valve 52 to correspond to a lower gas supply pressure, the orifice constituting the second shutoff valve 52 can be designed to be large, so that the pressure loss in the gas shutoff device 100 can be reduced.

Further, the leak detection unit 711 temporarily opens the second shutoff valve 52 when the pressure sensor 54 does not detect a predetermined pressure rise within a predetermined time after closing the first shutoff valve 51. The predetermined time is set, for example, in the range of 1 second to 99 seconds.
As a result, when a minute gas leak that is acceptable in the boiler 1 occurs in the first shutoff valve 51, the second shutoff valve 52 is temporarily pressed before the pressure in the connection path 53 reaches a predetermined pressure. The fuel gas introduced into the connecting path 53 can be discharged to the secondary side. Therefore, it is possible to prevent the pressure in the connecting path 53 from rising excessively due to a minute gas leak in the first shutoff valve 51, and the gas shutoff device 100 can be operated stably.

Further, in the present embodiment, when starting the combustion of the boiler 1, the control unit 71 opens the second shutoff valve 52 first and then opens the first shutoff valve 51 to the gas shutoff device 100. .. As a result, when the combustion of the boiler 1 is started, the second shutoff valve 52 can be opened before the fuel gas is supplied to the connection path 53, so that the second shutoff valve 52 has a lower pressure than the first shutoff valve 51. Even if the design corresponds to the gas supply pressure, the fuel gas supply can be started satisfactorily.

According to the gas shutoff device 100 of the present embodiment described above, the following effects are obtained.

(1) The gas shutoff device 100 measures the pressure in the connection path 53 connecting the first shutoff valve 51, the second shutoff valve 52, the first shutoff valve 51 and the second shutoff valve 52, and the connection path 53. The pressure sensor 54 and the leak detection unit 711 for detecting the leakage of the first shutoff valve 51 are included, and the first shutoff valve 51 is closed when the supply of fuel gas to the leak detection unit 711 is stopped. After that, the second shutoff valve 52 is closed, and when the pressure sensor 54 detects a pressure equal to or higher than a predetermined pressure after closing the first shutoff valve 51 and the second shutoff valve 52, the second shutoff valve 52 is opened. I restricted it. As a result, the opening operation of the second shutoff valve 52 can be prohibited when a leak is detected in the first shutoff valve 51, and the pressure in the connection path 53 when no leak occurs in the first shutoff valve 51 is increased. It can be atmospheric pressure. Therefore, since the gas shutoff device 100 can be configured so that the second shutoff valve 52 is designed to correspond to the gas supply pressure lower than that of the first shutoff valve 51, the actuator that drives the second shutoff valve 52 can be miniaturized, and the manufacturing cost can be reduced. The gas shutoff device 100 can be manufactured with a simple configuration while reducing the cost. Further, by designing the second shutoff valve 52 to correspond to a lower gas supply pressure, the orifice constituting the second shutoff valve 52 can be designed to be large, so that the pressure loss in the gas shutoff device 100 can be reduced.

(2) When starting the supply of fuel gas to the control unit 71, the first shutoff valve 51 was opened after the second shutoff valve 52 was opened. As a result, when the combustion of the boiler 1 is started, the second shutoff valve 52 can be opened before the fuel gas is supplied to the connection path 53, so that the second shutoff valve 52 has a lower pressure than the first shutoff valve 51. Even if the design corresponds to the gas supply pressure, the fuel gas supply can be started satisfactorily.

(3) After closing the first shutoff valve 51, the leak detection unit 711 temporarily opens the second shutoff valve 52 when the pressure sensor 54 does not detect a predetermined pressure rise within a predetermined time. rice field. As a result, when a minute gas leak that is acceptable in the boiler 1 occurs in the first shutoff valve 51, the second shutoff valve 52 is temporarily pressed before the pressure in the connection path 53 reaches a predetermined pressure. The fuel gas introduced into the connecting path 53 can be released to the secondary side. Therefore, it is possible to prevent the pressure in the connecting path 53 from rising excessively due to a minute gas leak in the first shutoff valve 51, and the gas shutoff device 100 can be operated stably.

(4) The gas shutoff device 100 is configured to include a pressure release valve 55. As a result, when the leak detection unit 711 detects a pressure equal to or higher than a predetermined pressure higher than the pressure for determining gas leakage by the leak detection unit 711 in the pressure sensor 54, the fuel gas is released from the pressure release valve 55. Therefore, the safety of the gas shutoff device 100 can be enhanced.

Although the preferred embodiment of the gas shutoff device 100 of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be appropriately modified.
For example, in the present embodiment, the gas shutoff device 100 is applied to the boiler 1, but the present invention is not limited to this. The gas shutoff device can be applied to a combustion device that uses a gaseous fuel other than a boiler.
Further, in the present embodiment, the leak detection unit 711 is configured as a part of the control device 70 of the boiler 1, but the present invention is not limited to this. That is, the leak detection unit 711 may be configured as a control unit different from the boiler control device.

51 1st shutoff valve 52 2nd shutoff valve 53 Connection path 54 Pressure sensor (pressure measuring unit)
55 Pressure release valve 71 Control unit 711 Leakage detection unit 100 Gas shutoff device

Claims (4)

The first shutoff valve and
A second shutoff valve arranged on the downstream side of the first shutoff valve,
A connection path connecting the first shutoff valve and the second shutoff valve,
A pressure measuring unit that measures the pressure in the connecting path,
A gas shutoff device including the first shutoff valve and a control unit for controlling the second shutoff valve.
The control unit includes a leak detection unit that detects a gas leak from the first shutoff valve.
The leak detection unit
After closing the first shutoff valve, the second shutoff valve is closed.
A gas shutoff device that limits the opening operation of the second shutoff valve when the pressure measuring unit detects a pressure equal to or higher than a predetermined pressure after closing the first shutoff valve and the second shutoff valve. The gas shutoff device according to claim 1, wherein when the control unit starts supplying gas, the second shutoff valve is opened and then the first shutoff valve is opened. A claim that the leak detecting unit temporarily opens the second shutoff valve when a predetermined pressure increase is not detected in the pressure measuring unit within a predetermined time after closing the first shutoff valve. The gas shutoff device according to 1 or 2. The gas shutoff device according to any one of claims 1 to 3, further comprising a pressure release valve arranged in the connection path.

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