Switching valve for burner and fuel control device for burner

Abstract

To reduce the cost of the whole fuel control device for a burner by reducing the number of devices installed in the fuel control device for the burner for supplying fuel to the burner.SOLUTION: A directional control valve 2 arranged in a feed line L11 to feed fuel to a burner is provided with a first inlet port 23 to which fuel enters, a second inlet port 24 to which inert gas enters, an outlet port 25 capable of outputting fuel and inert gas to the burner 5 and a directional control valve part. The switching valve portion switches between a first state in which the first input port 23 and the output port 25 communicate with each other and a second state in which the second input port 24 and the output port 25 communicate with each other. The switching valve 2 has a communication flow passage that constantly communicates the second input port 24 with the output port 25.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a burner fuel control device and a burner fuel control method for selectively supplying fuel or inert gas to a burner that burns fuel. [Background technology]

[0002] Traditionally, natural gas, propane gas, etc. have been used as fuel for burners used in combustion equipment such as boilers, industrial furnaces, and water coolers and heaters. However, with growing environmental awareness in recent years, the use of hydrogen gas as fuel has been promoted in order to reduce CO2 emissions.

[0003] However, because hydrogen gas has a faster combustion speed than conventional fuels, when the burner starts or stops combustion, the flame generated in the burner may flow back into the supply line that supplies fuel to the burner (hereinafter, this flame backflow phenomenon will be referred to as "backfire"). This backfire is prevented by using a backfire prevention device (flame arrester).

[0004] Installing a flame arrester is costly. Therefore, for example, Patent Document 1 discloses a technology for a burner fuel control device that includes a fuel gas supply passage that supplies hydrogen gas to a burner and an inert gas supply passage that connects a nitrogen gas supply source and the fuel gas supply passage, in which nitrogen gas is constantly supplied to the fuel gas supply passage to prevent a combustible mixture of hydrogen gas and air from being formed in the fuel gas supply passage. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-3430 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology described in Patent Document 1 can prevent flashback at low cost without using a flame arrester, but it requires fluid control devices for controlling hydrogen gas and nitrogen gas to be installed in the fuel gas supply line and the inert gas supply line, respectively. Therefore, the technology described in Patent Document 1 requires many devices to be installed in the fuel control device that supplies fuel to the burner, which increases the cost of the entire fuel control device. [Means for solving the problem]

[0007] A burner switching valve developed to solve the above problems is (1) a burner switching valve that switches the flow of fuel supplied to a burner that combusts the fuel, and is configured to have a first input port through which the fuel is input, a second input port through which an inert gas is input, an output port that can output the fuel and the inert gas to the burner, a switching valve unit that switches between a first state in which the first input port and the output port are connected to each other and a second state in which the second input port and the output port are connected to each other, and a communication flow path that constantly connects the second input port to the output port.

[0008] When the switching valve for a burner having the above configuration is in the first state, the flow rate of the inert gas added to the fuel flowing from the first input port to the output port can be adjusted by the communication passage, even without a separate fluid control device for controlling the flow rate of the inert gas. When the switching valve for a burner is in the second state, the amount of inert gas output from the output port is increased by the amount of inert gas ejected from the communication passage compared to when there is no communication passage, preventing the generation of a flammable mixture of air and fuel in the supply line that supplies fuel to the burner. In other words, the switching valve for a burner can prevent flashback without installing a flame arrester. Therefore, the switching valve for a burner can reduce the amount of equipment installed in the burner fuel control device that supplies fuel to the burner, thereby reducing the overall cost of the burner fuel control device.

[0009] (2) In the burner switching valve described in (1), it is preferable that the second input port, the communication passage, and the output port are formed coaxially.

[0010] In the burner switching valve having the above configuration, inert gas input to the second input port flows into the communicating passage while maintaining its flow, and is then ejected from the communicating passage to the output port. When the switching valve unit is in the first state, the burner switching valve uses the momentum of the inert gas ejected from the communicating passage to agitate and mix the inert gas with fuel to generate a mixed gas, which is output from the output port. Therefore, the burner switching valve can switch between inert gas and a mixed gas adjusted to a predetermined fuel concentration and supply it to the burner without considering the responsiveness of other fluid control devices, thereby reducing the effort required to design a burner fuel control device.

[0011] (3) In the burner switching valve described in (1) or (2), it is preferable that the switching valve has a space formed between the first input port, the second input port, and the output port, a first valve port that connects the first input port to the space, and a second valve port that connects the second input port to the space, the first valve port and the second valve port being formed coaxially along a direction perpendicular to the communication flow path, the switching valve section having a first valve seat provided along the outer periphery of the opening of the first valve port, a second valve seat provided along the outer periphery of the opening of the second valve port, and a valve body that abuts or is spaced apart from the first valve seat and the second valve seat relatively, and the communication flow path is formed at a position closer to the second input port than the second valve seat.

[0012] The burner switching valve having the above configuration can switch between inert gas and mixed gas by linearly reciprocating the valve element and relatively abutting or separating from the first valve seat and the second valve seat. Because the communication passage is formed at a position closer to the second input port than the second valve seat, even when the valve element is abutting against the second valve seat, the inert gas input to the second input port is ejected from the communication passage and mixed with the fuel flowing from the first input port to the output port. Therefore, the burner switching valve can add inert gas to fuel with an adjusted flow rate using a compact structure.

[0013] (4) In the burner switching valve described in any one of (1) to (3), it is preferable to have a flow rate adjusting mechanism that adjusts the flow rate of the inert gas flowing through the communication passage.

[0014] The burner switching valve having the above-described configuration can change the amount of inert gas supplied without a separate fluid control device being provided for adjusting the amount of inert gas supplied.

[0015] (5) In the burner switching valve described in (4), it is preferable that the flow rate adjustment mechanism has a displaceable covering portion that can cover the flow path opening of the communicating flow path, and adjusts the flow rate of the inert gas flowing through the communicating flow path by changing the coverage ratio of the covering portion to the flow path opening of the communicating flow path based on the displacement of the covering portion.

[0016] The burner switching valve having the above-described configuration can adjust the flow rate of the inert gas by displacing the covering portion to change the opening area of ​​the flow passage opening of the communication flow passage. Therefore, the burner switching valve does not need to adjust the supply amount of inert gas taking into account the responsiveness of multiple fluid control devices, and the effort required to design a burner fuel control device can be reduced.

[0017] (6) In the burner switching valve described in (5), it is preferable that the valve has a cylindrical shape along a direction perpendicular to the axis of the communicating flow passage and has an accommodation hole connected to the end of the communicating flow passage located on the second input port side, and the flow rate adjustment mechanism has a rotating body rotatably accommodated in the accommodation hole and integrally formed with the covering portion, and a rotation operating portion for rotating the rotating body.

[0018] The burner switching valve having the above configuration has a compact structure in which the flow control mechanism is a rotor equipped with a covering portion that is rotatably housed in an accommodation hole, so the valve size is kept small even when an inert gas flow control function is added.

[0019] A fuel control device for a burner of a different aspect from the above is (7) a fuel control device for a burner arranged in a supply line that supplies fuel to a burner that combusts the fuel, and having a burner switching valve and an on-off valve, wherein the burner switching valve has a first input port through which the fuel is input, a second input port through which an inert gas is input, an output port that can output the fuel and the inert gas to the burner, a switching valve unit that switches between a first state that connects the first input port to the output port and a second state that connects the second input port to the output port, and a communication flow path that always connects the second input port to the output port, and the on-off valve is arranged downstream of the burner switching valve and is configured to control the output of the gas input from the burner switching valve to the burner.

[0020] In the burner fuel control device having the above configuration, an on-off valve disposed downstream of the burner switching device described in any one of (1) to (6) above inputs gas output from the burner switching valve and controls the supply to the burner. With such a burner fuel control device, flashback can be prevented by simply providing a communicating flow path, without the need to install a flame arrester or a separate flow control device for controlling the inert gas, and the amount of inert gas supplied can also be adjusted.

[0021] In addition, a method, a program, and a storage medium for storing the program having the same functions as the burner fuel control device described above are also novel and useful. [Effects of the Invention]

[0022] The burner switching valve having the above configuration can provide a technology for reducing the number of devices installed in a burner fuel control device that supplies fuel to the burner, and suppressing the overall cost of the burner fuel control device. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram of a fuel system using a burner switching valve according to an embodiment of the present invention. [Figure 2]FIG. 2 is a diagram illustrating the configuration of a switching valve and an on-off valve of the burner fuel control device. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] 10A and 10B are diagrams illustrating displacement of a covering portion. [Figure 7] 10A and 10B are diagrams illustrating displacement of a covering portion. [Figure 8] 10A and 10B are diagrams illustrating displacement of a covering portion. [Figure 9] FIG. 4 is a diagram for explaining the fuel control process, showing the states of the first valve device and the second valve device when the system is in a stopped state. [Figure 10] 10 is a diagram for explaining the fuel control process, showing the states of the switching valve and the on-off valve when pre-purging is performed. FIG. [Figure 11] 10 is a diagram for explaining the fuel control process, showing a state in which the switching valve is in the middle of transitioning from the first state to the second state when ignition is performed. FIG. [Figure 12] FIG. 10 is a diagram for explaining the fuel control process, showing the state immediately after the switching valve has completed transition to the second state when ignition is performed. [Figure 13] FIG. 10 is a diagram for explaining the fuel control process, showing the state in which mixed gas is generated when ignition is performed. [Figure 14] FIG. 10 is a diagram for explaining the fuel control process, showing the state in which nitrogen gas is replaced with mixed gas when ignition is performed. [Figure 15] FIG. 10 is a diagram for explaining the fuel control process, showing a state in which the switching valve is in the middle of transitioning from the second state to the first state when extinguishing a fire. [Figure 16] FIG. 10 is a diagram for explaining the fuel control process, showing the state immediately after the switching valve has completed transition to the first state when extinguishing a fire. [Figure 17] 10 is a diagram for explaining the fuel control process, showing the states of the switching valve and the on-off valve when post-purging is performed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] A burner switching valve and a burner fuel control device according to an embodiment of the present invention will be described in detail with reference to the drawings. This specification discloses a burner switching valve and a burner fuel control device that supply fuel to a burner that combusts fuel.

[0025] (Outline of burner fuel control device configuration) As shown in Fig. 1, a burner switching valve 2 (hereinafter referred to as "switching valve 2") according to this embodiment is used in a burner fuel control device 1 (hereinafter referred to as "fuel control device 1"). The fuel control device 1 is a device for supplying fuel to a burner 5 provided in combustion equipment 4 such as a boiler, industrial furnace, or hot / cold water machine. The burner 5 combusts the fuel supplied from the fuel control device 1.

[0026] The fuel control device 1 includes a switching valve 2, an on-off valve 3, and a blower 6, which are electrically connected to a control unit 9. The fuel control device 1 includes a supply line L11 connected to a burner 5. The supply line L11 is a pipe for supplying hydrogen gas used for combustion or nitrogen gas to replace the hydrogen gas to the burner 5. Hydrogen gas is an example of a "fuel." Nitrogen gas is an example of an "inert gas." The supply line L11 is provided with a switching valve 2 and an on-off valve 3, in this order from the upstream side.

[0027] The switching valve 2 is a three-way valve having a first input port 23 , a second input port 24 , and an output port 25 .

[0028] A fuel supply source 7 that supplies hydrogen gas is connected to the first input port 23 via a hydrogen gas supply line L12. The supply pressure of hydrogen gas from the fuel supply source 7 is not particularly limited, but is, for example, 0.01 to 0.3 MPa. The hydrogen gas supply line L12 is a pipe that allows hydrogen gas supplied from the fuel supply source 7 to flow into the switching valve 2.

[0029] An inert gas supply source 8 that supplies nitrogen gas is connected to the second input port 24 via a nitrogen gas supply line L13. The supply pressure of the nitrogen gas from the inert gas supply source 8 is set to be higher than the supply pressure of hydrogen, although this is not particularly limited. The nitrogen gas supply line L13 is a pipe that allows the nitrogen gas supplied from the inert gas supply source 8 to flow into the switching valve 2.

[0030] An on-off valve 3 is connected to the output port 25. The switching valve 2 can switch between hydrogen gas input to the first input port 23 and nitrogen gas input to the second input port 24 and supply the selected gas to the output port 25, depending on the operation of an internal valve element 223 (see FIG. 2).

[0031] The on-off valve 3 is a two-way valve having an input port 33 and an output port 34. The input port 33 is connected to the output port 25 of the switching valve 2. The connection here may mean that the input port 33 is directly connected to the output port 25 of the switching valve 2, or that the input port 33 is connected via a pipe. When the input port 33 of the on-off valve 3 is connected to the output port 25 of the switching valve 2, the gas output from the switching valve 2 enters the input port 33.

[0032] A burner 5 is connected to the output port 34 via a supply line L11. The on-off valve 3 can control the output of gas input from the switching valve 2 to the burner 5 by opening and closing the valve. The specific configurations of the switching valve 2 and the on-off valve 3 will be described later.

[0033] A blower 6 is connected to the burner 5 via an air supply line L14. Combustion air is supplied to the burner 5 from the blower 6 through the air supply line L14. The burner 5 burns a combustible mixture of hydrogen gas and air.

[0034] The control unit 9 stores an executable control program for controlling the switching valve 2, the on-off valve 3, and the blower 6. The control unit 9 executes the control program to control the operations of the switching valve 2, the on-off valve 3, and the blower 6, thereby controlling the supply of hydrogen gas to the burner 5.

[0035] (Regarding switching valves) The above-mentioned switching valve 2 will be described in more detail with reference to FIG. 2. FIG. 2 shows the switching valve 2 switched to the second state and the on-off valve 3 in a closed state. The switching valve 2 is an air-operated pilot valve. The switching valve 2 includes a drive unit 21 and a valve unit 22, which are stacked vertically in the drawing. The valve unit 22 has the function of switching between hydrogen gas input to the first input port 23 and nitrogen gas input to the second input port 24 in accordance with the operation of the valve element 223. The drive unit 21 has the function of applying a drive force to the valve unit 22. The valve unit 22 is an example of a "switching valve unit."

[0036] The drive unit 21 has a disk-shaped piston 211 fitted inside a cylinder 212. A drive rod 215 is connected to the piston 211. The drive rod 215 extends from the drive unit 21 toward the valve unit 22, and a valve body 223 (described later) is connected to the end of the drive rod 215 opposite the piston 211 side.

[0037] The interior of the cylinder 212 is divided by the piston 211 into a first chamber 212a and a second chamber 212b in the vertical direction in the figure. An operation port 213 is provided in the first chamber 212a. The operation port 213 is connected to an operation air supply source (not shown). A breather hole 214 is provided in the second chamber 212b. The breather hole 214 is open to the atmosphere. The drive unit 21 introduces operation air into the first chamber 212a to increase the pressure in the first chamber 212a, thereby moving the piston 211 toward the second chamber 212b. At this time, air in the second chamber 212b is discharged to the outside through the breather hole 214.

[0038] The drive unit 21 is provided with a coil spring 216 in the second chamber 212b that applies a biasing force to the piston 211 toward the first chamber 212a. Therefore, when operating air is introduced into the first chamber 212a, the piston 211 moves toward the second chamber 212b (downward in FIG. 2) against the biasing force of the coil spring 216. When the introduction of operating air into the first chamber 212a is stopped, the piston 211 moves toward the first chamber 212a (upward in FIG. 2) due to the biasing force of the coil spring 216. As described above, the piston 211 moves up and down, and accordingly, the drive rod 215 connected to the piston 211 also moves up and down in accordance with the up and down movement of the piston 211.

[0039] The valve section 22 has a block-shaped valve body 20. The valve section 22 is opened on the side surface of the valve body 20 so that the first input port 23, the second input port 24, and the output port 25 appear on the same cross section. The valve body 20 has a pressure action chamber 224, a fluid chamber 222, a first valve port 221a, a space 221, a second valve port 221b, and a receiving hole 26, which are coaxially arranged along an axis extending in the vertical direction in the drawing (axis Z1 in FIG. 3).

[0040] The second input port 24 and the output port 25 are provided coaxially below the first input port 23 and along a direction perpendicular to the vertical axis in the figure (axis Z1 in FIG. 3). In this embodiment, the first input port 23, the second input port 24, and the output port 25 have the same port diameter, but they may have different diameters. The first input port 23 may be formed on a cross section different from the cross section on which the second input port 24 and the output port 25 appear.

[0041] The space 221 is formed between the first input port 23, the second input port 24, and the output port 25. The space 221 communicates with the first input port 23 via the first valve port 221a and the fluid chamber 222. The space 221 communicates with the second input port 24 via the second valve port 221b.

[0042] In the valve body 20, the drive rod 215 of the drive part 21 is inserted through the pressure action chamber 224, the fluid chamber 222 and the first valve port 221a, and the valve element 223 attached to the lower end of the drive rod 215 is disposed in the space 221.

[0043] As shown in FIG. 3, the space 221 has a valve element accommodating chamber 221m and a vertical flow path 221n. The valve element accommodating chamber 221m is a substantially cylindrical space and accommodates a valve element 223. The valve element 223 is arranged coaxially with the valve element accommodating chamber 221m, the first valve port 221a, and the second valve port 221b. The vertical flow path 221n extends downward from the lower inner wall of the valve element accommodating chamber 221m in the figure and communicates with the output port 25. The vertical flow path 221n is formed in an arc shape along the radially outer side of the second valve port 221b, on the opposite side of the second input port 24 with the second valve port 221b in between. The partition wall 201 is erected in an arc shape between the second valve port 221b and the vertical flow path 221n. The nitrogen gas input to the second input port 24 can flow into the space 221 via the second valve port 221b.

[0044] A communication passage 28 is formed penetrating the partition wall 201. The valve body 20 has a second input port 24, the communication passage 28, and an output port 25, which are coaxially arranged. The second input port 24 is always in communication with the output port 25 via the communication passage 28, regardless of the operation of the valve portion 22.

[0045] The flow path diameter of the communication flow path 28 is smaller than the port diameter of the second input port 24 and the inner diameter of the second valve opening 221b. The flow rate of the nitrogen gas input to the second input port 24 is reduced by the communication flow path 28, and the nitrogen gas is ejected toward the output port 25.

[0046] An accommodation hole 26 opens on the bottom surface of the valve body 20. The accommodation hole 26 is formed in a cylindrical shape and accommodates a flow rate adjustment mechanism 27. The flow rate adjustment mechanism 27 is a mechanism for adjusting the flow rate of nitrogen gas flowing through the communication flow path 28. The flow rate adjustment mechanism 27 will be described later.

[0047] An annular first valve seat 221c is provided on the upper inner wall of the valve element accommodating chamber 221m in the drawing, along the outer periphery of the opening of the first valve port 221a. An annular second valve seat 221d is provided on the lower inner wall of the valve element accommodating chamber 221m in the drawing, along the outer periphery of the opening of the second valve port 221b. The valve element 223 can be brought into contact with or separated from the first valve seat 221c and the second valve seat 221d by the movement of the drive rod 215 in the vertical direction in the drawing.

[0048] When the valve unit 22 is disposed in a "second position" in which the valve element 223 abuts against the second valve seat 221d and is spaced apart from the first valve seat 221c, the valve unit 22 is in a "first state" in which the first input port 23 and the output port 25 are in communication. In this first state, hydrogen gas input to the first input port 23 can flow to the output port 25 via the first valve port 221a and the space 221. In the first state, nitrogen gas input to the second input port 24 cannot flow from the second valve port 221b to the space 221, but flows from the communication flow path 28 to the vertical flow path 221n.

[0049] When the valve unit 22 is disposed in a "first position" in which the valve element 223 abuts against the first valve seat 221c and is spaced from the second valve seat 221d, the valve unit 22 is in a "second state" in which the second input port 24 and the output port 25 are in communication. In this second state, nitrogen gas input to the second input port 24 can flow to the output port 25 via the second valve port 221b and the space 221. The nitrogen gas also flows out into the vertical flow path 221n via the communication flow path 28. In the second state, hydrogen gas input to the first input port 23 cannot flow from the first valve port 221a to the space 221.

[0050] Flow rate adjustment mechanism 27 has a rotor 27A and a support 27B. Rotator 27A is rotatably housed in housing hole 26. An annular seal member 270 is disposed between the outer circumferential surface of rotor 27A and the inner circumferential surface of housing hole 26 to prevent gas leakage.

[0051] As shown in Fig. 4, the rotor 27A has a covering member 277 and a sealing member 273. The sealing member 273 has a generally cylindrical shape and includes a sealing main body portion 273m and a connecting portion 273n. The sealing main body portion 273m has an annular mounting groove 273c formed along its outer circumferential surface for mounting the seal member 270. The connecting portion 273n has a cylindrical shape with a smaller diameter than the sealing main body portion 273m and has an annular constricted portion 273b formed along the portion where it connects to the sealing main body portion 273m. Furthermore, the connecting portion 273n has a pin hole portion 273a formed radially inward from its outer circumferential surface.

[0052] A mating recess 277e into which the connecting portion 273n of the sealing member 273 is fitted is formed on the lower surface of the covering member 277. An engaging protrusion 277g that engages with the narrowed portion 273b of the connecting portion 273n protrudes radially inward from the inner wall of the mating recess 277e. An engaging pin 277h that is inserted into the pin hole 273a of the connecting portion 273n protrudes radially inward from the inner wall of the mating recess 277e.

[0053] The covering member 277 includes a covering portion 277a that is disposed along the inner wall of the second valve port 221b. The covering portion 277a is formed in a thin arc shape. The covering portion 277a has a height and arc length that enable it to cover the communication flow path 28. A guide ring portion 277f is integrally provided at the upper end of the covering portion 277a.

[0054] By sliding the covering member 277 relative to the sealing member 273, the engaging protrusions 277g engage with the constricted portion 273b from the side, and further, the engaging pins 277h fit into the pin holes 273a. The covering member 277 and the sealing member 273 are prevented from separating in the axial direction (the up-down direction in the figure) because the engaging protrusions 277g are hooked onto the constricted portion 273b. Furthermore, the covering member 277 and the sealing member 273 are able to rotate integrally in the rotational direction because the engaging pins 277h engage with the pin holes 273a.

[0055] 3, rotor 27A is fitted into the lower end opening of accommodation hole 26. The amount of fitting of rotor 27A into accommodation hole 26 is restricted by step portion 27C shown in FIG. 3, and covering portion 277a is disposed in a position where it can cover communicating flow path 28. Covering member 277 has inclined surface 277b for guiding nitrogen gas input into second input port 24 to communicating flow path 28.

[0056] The rotor 27A fitted into the receiving hole 26 is prevented from falling off by a C-ring 275 attached to the valve body 20 from below the rotor 27A.

[0057] The support body 27B has a fixed plate 271 fixed to the underside of the valve body 20 via fixing screws 272. The support body 27B is joined to the fixed plate 271 with a plurality of support pins 274 inserted into pin holes 271d (FIG. 4) of the fixed plate 271 and with their tip ends abutting against the underside of the rotating body 27A.

[0058] Rotating body 27A has a hexagonal hole 276 formed on the underside of sealing member 273. Fixing plate 271 has a window 271a for exposing hexagonal hole 276 to the outside. Rotating body 27A can displace covering portion 277a in the rotational direction by attaching a tool to hexagonal hole 276 via window 27a and applying a rotational force. Hexagonal hole 276 is an example of a "rotation operation portion."

[0059] 6 to 8 are diagrams illustrating the displacement of the covering portion 277a. The solid lines in FIGS. 6 to 8 indicate the flow rate adjustment mechanism 27 and the communicating flow path 28 as viewed from the second input port 24. The two-dot chain lines in FIGS. 6 to 8 indicate the valve body 20 and the second input port 24. FIG. 6 illustrates a state in which the coverage rate of the covering portion 277a to the flow path opening 281 located on the second input port 24 side of the communicating flow path 28 (hereinafter referred to as the "coverage rate") is 0%. FIG. 7 illustrates a state in which the coverage rate is 50%. FIG. 8 illustrates a state in which the coverage rate is 90%. For example, as shown in FIG. 6, when the coverage rate of the flow rate adjustment mechanism 27 is 0%, the entire flow path opening 281 of the communicating flow path 28 is open to the second input port 24 side. The opening degree of the communicating flow path 28 at this time is 100%.

[0060] 7, in the flow rate adjustment mechanism 27, as the rotor 27A is rotated in the predetermined direction K, the covering portion 277a is displaced in a direction in which it covers the flow path opening 281 of the communicating flow path 28. When the coverage ratio is 50%, half of the flow path opening 281 of the communicating flow path 28 is open to the second input port 24. The opening degree of the communicating flow path 28 at this time is set to 50%.

[0061] 8, as the rotor 27A rotates in the predetermined direction K, the flow rate adjustment mechanism 27 displaces the covering portion 277a, thereby increasing the coverage rate of the flow path opening 281 of the communicating flow path 28. When the coverage rate is 90%, only 10% of the flow path opening 281 of the communicating flow path 28 is open to the second input port 24. The opening rate of the communicating flow path 28 at this time is set to 10%. As the opening rate of the communicating flow path 28 decreases, the flow rate of the nitrogen gas flowing through the communicating flow path 28 decreases. In other words, the flow rate of the nitrogen gas mixed with the hydrogen gas decreases.

[0062] As the rotor 27A rotates in the direction opposite to the predetermined direction K, the coverage ratio of the flow rate adjustment mechanism 27 decreases and the opening of the communicating flow path 28 increases. As the opening of the communicating flow path 28 increases, the flow rate of the nitrogen gas flowing through the communicating flow path 28 increases. In other words, the flow rate of the nitrogen gas mixed with the hydrogen gas increases.

[0063] The degree of opening of communication flow path 28 cannot be seen from the outside. Therefore, as shown in Fig. 5, fixed plate 271 is provided with scale 279A on the outside of window portion 271a, which indicates the flow rate of nitrogen gas flowing through communication flow path 28. Rotating body 27A is provided with reference line 279B on the lower surface of sealing member 273, which indicates the position of covering portion 277a.

[0064] For example, when the rotor 27A is rotated so that the reference line 279B is aligned with the high level "H" of the scale 279A, the opening degree of the communicating flow path 28 is adjusted to 100%, as shown in Fig. 6. For example, when the rotor 27A is rotated so that the reference line 279B is aligned with the middle level "M" of the scale 279A, the opening degree of the communicating flow path 28 is adjusted to 50%, as shown in Fig. 7. For example, when the rotor 27A is rotated so that the reference line 279B is aligned with the low level "L" of the scale 279A, the opening degree of the communicating flow path 28 is adjusted to 10%, as shown in Fig. 8.

[0065] Rotating body 27A is supported from below by a plurality of support pins 274, so the rotation axis is unlikely to tilt even when rotation is repeated. Therefore, flow rate adjustment mechanism 27 can normally maintain the function of adjusting the flow rate by rotating rotating body 27A for a long period of time.

[0066] As shown in Figure 2, the switching valve 2 has a fail-safe feature, so that when the supply of operating air is cut off due to a power outage or the like, the force of the coil spring 216 causes the valve element 223 to abut against the first valve seat 221c, closing the first valve port 221a and shutting off the hydrogen gas.

[0067] Furthermore, the valve unit 22 has a pressure action chamber 224 between the fluid chamber 222 and the drive unit 21. The pressure action chamber 224 is in communication with the fluid chamber 222 via an internal flow path 226, so that hydrogen gas flowing into the fluid chamber 222 also flows into the pressure action chamber 224.

[0068] The drive rod 215 also includes a sub-piston 225. The end face of this sub-piston 225 facing the pressure application chamber 224 is a pressure application surface 225a that is subjected to the action of pressure from the hydrogen gas flowing into the pressure application chamber 224. The higher the pressure acting on the pressure application surface 225a, the more the sub-piston 225 applies an upward force in the figure to the drive rod 215. As a result, by placing the valve element 223 in the first position, the drive unit 21 can maintain the first position of the valve element 223 and block the flow of hydrogen even if the internal pressure of the fluid chamber 222 increases. Therefore, the sub-piston 225 can maintain a valve sealing force that abuts against the first valve seat 221c and closes the first valve port 221a. The sub-piston 225 functions as a fail-safe.

[0069] (On-off valve) The on-off valve 3 will be described in detail with reference to Fig. 2. The on-off valve 3 is a normally closed solenoid valve that is open when energized and closed when de-energized. As shown in Fig. 2, the on-off valve 3 includes a drive unit 31 and a valve unit 32 stacked one above the other.

[0070] The driving unit 31 has a cylindrical coil bobbin 311 therein. The coil bobbin 311 has a recess 311a on its outer periphery, and an exciting coil 312 is wound around the recess 311a. A fixed iron core 313 and a movable iron core 314 are inserted into a hollow portion 311b of the coil bobbin 311.

[0071] The fixed iron core 313 and the movable iron core 314 are arranged coaxially so that the bottom end surface of the fixed iron core 313 in FIG. 2 faces the top end surface of the movable iron core 314 in FIG. 2. The movable iron core 314 is movable up and down, and when current is passed through the excitation coil 312, the fixed iron core 313 is magnetized and attracts the movable iron core 314. As a result, the movable iron core 314 moves toward the fixed iron core 313 (upward in FIG. 2). In addition, a rod 315 is inserted into and fixed to the movable iron core 314. Therefore, when the fixed iron core 313 attracts the movable iron core 314, the rod 315 also moves in accordance with the movement of the movable iron core 314.

[0072] The valve section 32 includes an input port 33, an output port 34, and a valve chamber 322. The valve chamber 322 is in communication with the input port 33. Therefore, hydrogen gas or nitrogen gas flowing into the on-off valve 3 from the input port 33 can flow into the valve chamber 322. Furthermore, the valve chamber 322 is in communication with the output port 34 via a valve opening 322a. Therefore, the hydrogen gas or nitrogen gas flowing into the valve chamber 322 can be output from the output port 34.

[0073] The valve chamber 322 is provided with an annular valve seat 322b that surrounds the valve port 322a. The valve chamber 322 also contains a disk-shaped valve element 321, which is positioned coaxially with the valve port 322a. The valve element 321 is connected to a rod 315 that is inserted through the valve chamber 322. One end of a coil spring 324 abuts against the end face of the valve element 321 facing the drive unit 31. The other end of the coil spring 324 abuts against a flange member 323 that is disposed at a distance from the end face of the valve element 321 facing the drive unit 31, and the coil spring 324 is in a compressed state. The valve element 321 is therefore biased toward the valve seat 322b by the coil spring 324.

[0074] The valve element 321 as described above can move toward and away from the valve seat 322b due to the movement of the movable iron core 314 and the biasing force of the coil spring 324. More specifically, when the exciting coil 312 is not energized, the biasing force of the coil spring 324 moves the valve element 321 toward the valve seat 322b and brings it into contact with the valve seat 322b. On the other hand, when the exciting coil 312 is energized, the fixed iron core 313 is magnetized and the movable iron core 314 moves toward the fixed iron core 313. This causes the rod 315 to move upward in FIG. 2, and the valve element 223 connected to the rod 315 moves away from the valve seat 322b.

[0075] The on-off valve 3 is in a closed state when the valve element 321 abuts against the valve seat 322b, and hydrogen gas or nitrogen gas flowing into the on-off valve 3 from the input port 33 is not output from the output port 34. The on-off valve 3 is in an open state when the valve element 321 is away from the valve seat 322b, and hydrogen gas or nitrogen gas flowing into the on-off valve 3 from the input port 33 is output from the output port 34. As a fail-safe, when power is cut off due to a power outage or the like and no current is applied, the on-off valve 3 is closed by the biasing force of the coil spring 324.

[0076] (Fuel control) Next, control of the supply state of hydrogen gas and nitrogen gas to the burner 5 using the fuel control device 1 (hereinafter simply referred to as "fuel control") will be described with reference to Figures 9 to 17. In Figures 9 to 17, the gases flowing inside the switching valve 2, the on-off valve 3, the supply line L11, the hydrogen gas supply line L12, and the nitrogen gas supply line L13 are represented by dots. Specifically, hydrogen gas G11 is represented by the dots with the highest density, and nitrogen gas G12 is represented by the dots with the lowest density. The higher the relative density of the dots, the higher the hydrogen concentration (the lower the nitrogen concentration).

[0077] Here, we will explain the fuel control from the system stopped state, when combustion of the burner 5 is started, and from the state in which combustion of the burner 5 is ongoing, until combustion of the burner 5 is stopped and the system is stopped again. Note that the above "system stopped state" means a state in which the operation of the combustion equipment 4 is stopped. In addition, hereinafter, starting combustion of the burner 5 will be simply referred to as "ignition," and stopping combustion of the burner 5 will be simply referred to as "extinguishing."

[0078] (System stopped) Fuel control is performed by controlling the operation of the switching valve 2 and the on-off valve 3 according to a control program stored in the control unit 9. When the system is stopped, as shown in FIG. 9, the switching valve 2 has the valve element 223 in the first position, and the on-off valve 3 is in a closed state. That is, in the switching valve 2, the hydrogen gas G11 is blocked, while the nitrogen gas G12 flows from the second valve port 221b to the valve element accommodating chamber 221m of the space 221 and is output from the output port 25 (second state). Furthermore, the nitrogen gas G12 flows from the communication flow path 28 to the vertical flow path 221n of the space 221 and is output from the output port 25. The nitrogen gas G12 output from the output port 25 is blocked by the on-off valve 3. That is, neither the hydrogen gas G11 nor the nitrogen gas G12 flows through the supply line L11.

[0079] (Pre-purge step) To ignite the burner 5 from a system stopped state, pre-purge control is started to purge the supply line L11 with nitrogen gas G12 before ignition. As shown in Fig. 10, the pre-purge control is performed by opening the on-off valve 3 while maintaining the valve element 223 of the switching valve 2 in the first position (i.e., while maintaining the switching valve 2 in the second position).

[0080] By opening the on-off valve 3 while maintaining the valve element 223 of the switching valve 2 in the first position, the nitrogen gas G12 that had been flowing into the on-off valve 3 is output from the output port 34 of the on-off valve 3 and flows through the supply line L11. At this time, the flow rate of the nitrogen gas G12 is controlled by the second valve port 221b and the communication flow path 28, the opening of which is adjusted by the flow rate adjustment mechanism 27.

[0081] In this way, by flowing nitrogen gas G12 into the supply line L11, the air in the supply line L11 is replaced with nitrogen gas G12. This makes it possible to prevent the generation of a flammable mixture of air and hydrogen gas G11 in the supply line L11, thereby preventing backfire during ignition. Therefore, the burner 5 can be ignited safely.

[0082] (Ignition step) After a predetermined time (first predetermined time) has elapsed since the start of pre-purging, the burner 5 is ignited. The burner 5 is ignited by positioning the valve element 223 of the switching valve 2 to the second position (i.e., switching the switching valve 2 from the second state to the first state) while maintaining the on-off valve 3 in the open state.

[0083] As shown in Figure 11, while the valve body 223 of the switching valve 2 moves from the first valve seat 221c to the second valve seat 221d, the hydrogen gas G11 flowing out from the first valve port 221a and the nitrogen gas G12 flowing out from the second valve port 221b collide with each other in the valve body accommodating chamber 221m, are stirred and mixed, and a mixed gas G13 is generated.

[0084] 12, because the on-off valve 3 is in an open state, the mixed gas G13 flows from the valve element accommodating chamber 221m to the vertical flow path 221n without flowing back to the first valve port 221a and the second valve port 221b. Nitrogen gas G12 is ejected from the communicating flow path 28 into the vertical flow path 221n. When the mixed gas G13 flows from the vertical flow path 221n to the output port 25, it is stirred and mixed with the nitrogen gas G12 ejected from the communicating flow path 28. As a result, a mixed gas G14 having a lower hydrogen concentration (higher nitrogen concentration) than the mixed gas G13 is produced.

[0085] By placing the valve element 223 of the switching valve 2 in the second position, the nitrogen gas G12 is blocked, and the hydrogen gas G11 flows from the valve element accommodating chamber 221m to the vertical flow path 221n following the mixed gas G13.

[0086] 13, the hydrogen gas G11 flowing through the vertical flow path 221n is stirred and mixed with the nitrogen gas G12 ejected from the communicating flow path 28 to generate a mixed gas G15. Since the mixed gas G15 is made up of only the nitrogen gas G12 whose flow rate is controlled by the communicating flow path 28 being added to the hydrogen gas G11, the hydrogen concentration of the mixed gas G15 is higher (the nitrogen concentration is lower) than that of the mixed gas G14.

[0087] 14, the mixed gas G15 is supplied to the supply line L11 while pushing the nitrogen gas G12 and mixed gas G14 flowing ahead of it downstream. As a result, the nitrogen gas G12 that filled the supply line L11 during pre-purging is replaced with the mixed gas G15.

[0088] When the mixed gas G14 reaches the burner 5, it is ignited, for example, by a pilot burner provided in the combustion equipment 4, and combustion of the hydrogen gas begins in the burner 5. The above-mentioned predetermined time (first predetermined time) means the time for which pre-purging continues, and is set appropriately based on the volume of the supply line L11, the flow rate of the inert gas to be supplied, etc., to a time that allows sufficient purging with the nitrogen gas G12 to be performed.

[0089] The burner 5 is ignited with mixed gas G14 having a low hydrogen concentration, and continues combustion with mixed gas G15 in which the hydrogen concentration is adjusted according to the required heat quantity. This prevents damage to equipment due to the impact at the time of ignition. The amount of heat generated by the burner 5 gradually increases.

[0090] (Continued burning) After ignition, while the burner 5 continues to burn, the valve element 223 of the switching valve 2 is maintained in the second position (i.e., the switching valve 2 is maintained in the first position), and the on-off valve 3 is maintained in the open state, as shown in Fig. 14. As a result, the mixed gas G15 continues to be supplied to the burner 5 through the supply line L11, and the burner 5 can continue to burn.

[0091] (Fire extinguishing steps) The burner 5 is extinguished by positioning the valve element 223 of the switching valve 2 in the first position (i.e., switching the switching valve 2 from the first state to the second state) while keeping the on-off valve 3 open. When extinguishing the burner 5, post-purging of the supply line L11 is performed. Post-purging of the supply line L11 means purging the supply line L11 with nitrogen gas G12 when extinguishing the burner 5.

[0092] 15, the valve element 223 of the switching valve 2 moves from the second valve seat 221d to the first valve seat 221c. During this movement, the hydrogen gas G11 flowing out from the first valve port 221a and the nitrogen gas G12 flowing out from the second valve port 221b collide with each other in the valve element accommodating chamber 221m, are stirred and mixed, and a mixed gas G16 is generated. The second valve port 221b has a larger flow path opening area than the communication flow path 28. Therefore, the mixed gas G16 has a lower hydrogen concentration than the mixed gas G15.

[0093] 16, since the on-off valve 3 is in an open state, the mixed gas G16 flows from the valve element accommodating chamber 221m to the vertical flow path 221n without flowing back to the first valve port 221a and the second valve port 221b. Nitrogen gas G12 is ejected from the communicating flow path 28 into the vertical flow path 221n. When the mixed gas G16 flows from the vertical flow path 221n to the output port 25, it is stirred and mixed with the nitrogen gas G12 ejected from the communicating flow path 28. As a result, a mixed gas G17 having an even lower hydrogen concentration (higher nitrogen concentration) than the mixed gas G16 is produced.

[0094] When the switching valve 2 is in the second state, the hydrogen gas G11 is blocked, and the nitrogen gas G12 flows from the valve element accommodating chamber 221m to the vertical flow passage 221n following the mixed gas G16.

[0095] 17, the nitrogen gas G12 that has flowed into the vertical flow path 221n is merged with the nitrogen gas G12 that is ejected from the communication flow path 28, and is output from the output port 25. The nitrogen gas G12 pushes the previous mixed gas G17 and mixed gas G15 downstream, and the mixed gas G15 that filled the supply line L11 during fuel combustion is replaced with the nitrogen gas G12.

[0096] Following the mixed gas 15, mixed gas G14, which has a lower hydrogen concentration (higher nitrogen concentration) than mixed gas 15, flows through the supply line L11, followed by nitrogen gas G12. Therefore, as the post-purging progresses, the concentration of hydrogen gas G11 remaining in the supply line L11 gradually decreases, and the burner 5 naturally extinguishes. Finally, the supply line L11 is filled with nitrogen gas G12 (resulting in a state similar to that shown in FIG. 10).

[0097] In this way, the burner 5 is extinguished by replacing the gas in the supply line L11, so that hydrogen gas G11 does not remain in the supply line L11 and backfire can be prevented, thereby enabling the burner 5 to be extinguished safely.

[0098] (System shutdown steps) The system is shut down after a predetermined time (second predetermined time) has elapsed since the start of post-purging. The system is shut down by closing the on-off valve 3 while maintaining the valve element 223 of the switching valve 2 in the first position (i.e., maintaining the switching valve 2 in the second position). In other words, the system is shut down by setting the switching valve 2 and the on-off valve 3 to the state shown in FIG. 9. The above-mentioned predetermined time means the time for which post-purging continues, and is set appropriately to a time that allows sufficient purging with the nitrogen gas G12 to be performed, based on the volume of the supply line L11, the flow rate of the nitrogen gas G12 to be supplied, etc.

[0099] (Regarding nitrogen gas flow rate adjustment) For example, the fuel control device 1 measures the amount of NOx generated when the burner 5 burns fuel. If the amount of NOx generated is higher than a threshold, for example, the control program issues an instruction to reduce the flow rate of the nitrogen gas G12. The notification method may be audio or a screen display. Upon confirming the notification, the worker attaches a tool to the hexagonal hole 276 of the switching valve 2 and rotates the rotor 27A in the predetermined direction K to reduce the opening of the communicating flow path 28. This reduces the amount of nitrogen gas G12 added to the hydrogen gas G11 from the communicating flow path 28, thereby suppressing the amount of NOx generated.

[0100] For example, if an operator wishes to shorten the pre-purge time, the operator attaches a tool to the hexagonal hole 276 of the switching valve 2 and rotates the rotor 27A in the direction opposite to the predetermined direction K to increase the opening of the communicating flow path 28. This increases the flow rate of the nitrogen gas G12 added to the hydrogen gas G11 from the communicating flow path 28. This increases the flow rate of the nitrogen gas G12 output from the output port 25 during pre-purge, thereby shortening the pre-purge time. Note that after the pre-purge is completed and before igniting the burner 5, the operator may rotate the rotor 27A in the predetermined direction K to adjust the flow rate of the nitrogen gas G12 to a set flow rate.

[0101] Furthermore, for example, when the hydrogen concentration of the mixed gas G15 supplied to the burner 5 is changed, the operator attaches a tool to the hexagonal hole 276 of the switching valve 2 and rotates the rotor 27A in accordance with the changed hydrogen concentration to adjust the opening of the communicating flow path 28. This changes the flow rate of the nitrogen gas G12 added to the hydrogen gas G11 from the communicating flow path 28, thereby changing the hydrogen concentration of the mixed gas G15.

[0102] In this way, the switching valve 2 can adjust the supply amount of the nitrogen gas G12 using the flow rate adjustment mechanism 27, even if a separate fluid control device for adjusting the supply amount of the nitrogen gas G12 is not provided.

[0103] The flow rate adjustment mechanism 27 can adjust the supply amount of nitrogen gas G12 by displacing the covering portion 277a. Therefore, the switching valve 2 does not need to adjust the supply amount of nitrogen gas G12 in consideration of the responsiveness of multiple fluid control devices, which reduces the effort required to design the fuel control device 1.

[0104] (About the effects) As described above, when the valve unit 22 is in the first state, the switching valve 2 of this embodiment can adjust the flow rate of the nitrogen gas G12 added to the hydrogen gas G11 flowing from the first input port 23 to the output port 25 using the communication flow path 28, even without a separate fluid control device for controlling the flow rate of the nitrogen gas G12. When the valve unit 22 is in the second state, the switching valve 2 increases the amount of nitrogen gas G12 output from the output port 25 by the amount of nitrogen gas G12 ejected from the communication flow path 28 compared to when the communication flow path 28 is not provided, thereby preventing the generation of a flammable mixture of air and hydrogen gas G11 in the supply line L11 that supplies the hydrogen gas G11 to the burner 5. In other words, the switching valve 2 can prevent flashback without installing a flame arrester. Therefore, the switching valve 2 can reduce the number of devices installed in the fuel control device 1 that supplies the hydrogen gas G11 to the burner 5, thereby reducing the overall cost of the fuel control device 1.

[0105] The above-described embodiment is merely an example and does not limit the present invention in any way. Therefore, the present invention can naturally be improved and modified in various ways without departing from the spirit and scope of the present invention. For example, the switching valve 2 may be a solenoid valve. For example, the switching valve 2 may be an air-operated valve.

[0106] For example, in the above embodiment, hydrogen gas G11 is used as the fuel and nitrogen gas G12 is used as the inert gas, but these are not limited to these. For example, methane gas, propane gas, acetylene gas, etc. may be used as the fuel. For example, argon gas, helium gas, etc. may be used as the inert gas.

[0107] For example, the second input port 24, the communicating passage 28, and the output port 25 do not have to be coaxial. However, when the second input port 24, the communicating passage 28, and the output port 25 are coaxially formed in the switching valve 2, the nitrogen gas G12 input to the second input port 24 flows into the communicating passage 28 while maintaining its flow, and is then ejected from the communicating passage 28 to the output port 25. When the valve unit 22 is in the first state, the switching valve 2 uses the momentum of the nitrogen gas G12 ejected from the communicating passage 28 to agitate and mix the nitrogen gas G12 and the hydrogen gas G11 to generate a mixed gas G15, which is output from the output port 25. This switching valve 2 can switch between the nitrogen gas G12 and the mixed gas G15 adjusted to a predetermined hydrogen concentration and supply it to the burner 5 without considering the responsiveness of other fluid control devices, thereby reducing the effort required to design the fuel control device 1.

[0108] For example, the switching valve 2 may include a first valve element that contacts or moves away from the first valve seat 221c and a second valve element that contacts or moves away from the second valve seat 221d, and the operations of the first valve element and the second valve element may be controlled separately. However, as long as the first valve port 221a and the second valve port 221b are arranged coaxially along a direction perpendicular to the communication flow path 28, the switching valve 2 can switch between the nitrogen gas G12 and the mixed gas G15 by the valve element 223 making a linear reciprocating motion to contact or move away from the first valve seat 221c and the second valve seat 221d relatively. Because the communicating flow path 28 is formed at a position closer to the second input port 24 than the second valve seat 221d, even when the valve element 223 is in contact with the second valve seat 221d, the nitrogen gas G12 input to the second input port 24 is ejected from the communicating flow path 28 and mixed with the hydrogen gas G11 flowing from the first input port 23 to the output port 25. Therefore, the switching valve 2 can add flow-adjusted nitrogen gas G12 to the hydrogen gas G11 with a compact structure.

[0109] For example, the flow rate adjustment mechanism 27 may be omitted. However, by having the flow rate adjustment mechanism 27 that adjusts the flow rate of the nitrogen gas G12 flowing through the communication flow path 28, the switching valve 2 can change the supply amount of the nitrogen gas G12 even if a separate fluid control device for controlling the nitrogen gas G12 is not provided.

[0110] For example, flow rate adjustment mechanism 27 may change the coverage rate of communicating flow path 28 by displacing covering portion 277a in a direction intersecting the axis of communicating flow path 28. However, because flow rate adjustment mechanism 27 has a compact structure in which rotor 27A equipped with covering portion 277a is rotatably housed in housing hole 26, the valve size is kept small even when a flow rate adjustment function for nitrogen gas G12 is added. Furthermore, the switching valve 2 is easy to use because the components of flow rate adjustment mechanism 27 do not protrude outside when adjusting the flow rate. [Explanation of symbols]

[0111] 1. Burner fuel control device 2 Burner switching valve 3 On-off valve 5 Burner 22 Valve section 23 First input port 24 Second input port 25 output ports 26 Storage Cave 27 Flow rate adjustment mechanism 27A Rotating body 277a Covering part 28 Connecting flow path 281 Flow path opening 221 Space section 221a First valve opening 221b 2nd valve port 221c 1st valve seat 221d Second valve seat 223 Valve body G11 Hydrogen gas G12 Nitrogen gas G15 mixed gas

Claims

1. A burner switching valve that switches the flow of fuel supplied to a burner that burns fuel, a first input port through which the fuel is input; a second input port for inputting an inert gas; an output port capable of outputting the fuel and the inert gas to the burner; a switching valve unit that switches between a first state in which the first input port and the output port are communicated with each other and a second state in which the second input port and the output port are communicated with each other; a communication flow path that constantly connects the second input port to the output port; having A burner switching valve configured as follows.

2. 2. The burner switching valve according to claim 1, The second input port, the communication flow path, and the output port are coaxially formed. A burner switching valve configured as follows.

3. 2. The burner switching valve according to claim 1, a space formed between the first input port, the second input port, and the output port; a first valve port that connects the first input port to the space; a second valve port that connects the second input port to the space; and the first valve port and the second valve port are formed coaxially along a direction perpendicular to the communication flow path, The switching valve unit is a first valve seat provided along an outer periphery of the opening of the first valve port; a second valve seat provided along the outer periphery of the opening of the second valve port; a valve body that is in contact with or spaced apart from the first valve seat and the second valve seat; and the communication passage is formed at a position closer to the second input port than the second valve seat; A burner switching valve configured as follows.

4. The burner switching valve according to any one of claims 1 to 3, a flow rate adjusting mechanism for adjusting the flow rate of the inert gas flowing through the communication flow path; A burner switching valve configured as follows.

5. 5. The burner switching valve according to claim 4, The flow rate adjustment mechanism includes: a displaceable covering portion capable of covering a flow path opening of the communication flow path; A burner switching valve configured as follows.

6. 6. The burner switching valve according to claim 5, a receiving hole provided in a cylindrical shape along a direction perpendicular to the axis of the communication flow path and connected to an end of the communication flow path located on the second input port side; The flow rate adjustment mechanism includes: a rotor rotatably accommodated in the accommodation hole and integrally provided with the covering portion; a rotation operation unit that rotates the rotating body; having A burner switching valve configured as follows.

7. A burner fuel control device disposed in a supply line that supplies fuel to a burner that burns the fuel, A burner switching valve and an on-off valve are provided. The burner switching valve is a first input port through which the fuel is input; a second input port for inputting an inert gas; an output port capable of outputting the fuel and the inert gas to the burner; a switching valve unit that switches between a first state in which the first input port and the output port are communicated with each other and a second state in which the second input port and the output port are communicated with each other; a communication flow path that constantly connects the second input port to the output port; and the on-off valve is disposed downstream of the burner switching valve and controls the output of the gas input from the burner switching valve to the burner. A fuel control device for a burner configured as follows.

Images