Burner shutoff valve

Abstract

To provide an air-cooling type burner cutoff valve which can reduce an operation cost.SOLUTION: A burner cutoff valve 25 comprises: a valve plate 43 which is installed on a combustion gas flow passage 21 extending to a combustion chamber 20 from a burner 24 of a blast furnace, and which can block the combustion gas flow passage 21 by advancing into the combustion gas flow passage 21; a valve seat 44 formed into a shape surrounding the combustion gas flow passage 21, and allowing the valve plate 43 to be seated thereon; and an air blowout port 441 formed on a seat face of the valve seat 44, and blowing a cooling gas. The burner cutoff valve also has a bypass pipe 51 for supplying air branched from a combustion air pipe 23 which supplies combustion air to the burner 24, to the air blowout port 441 as the cooling air.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a burner shutoff valve. [Background technology]

[0002] A hot stove for supplying hot air is installed alongside a blast furnace for making pig iron. For example, a hot stove of the top combustion type is available, in which a burner is installed in a combustion chamber at the top of the furnace (see Patent Document 1). A burner shutoff valve capable of shutting off the flow path of the combustion gas from the burner is installed between the burner and the combustion chamber of the hot stove. The burner shutoff valve has a structure in which a valve plate is advanced into the flow path of the combustion gas and seated on an annular valve seat that surrounds the flow path. In burner shutoff valves, the valve plate and the valve seat need to be appropriately cooled in order to maintain the sealing performance around the entire circumference of the valve plate and the valve seat. For this reason, water-cooled burner shutoff valves, in which water with a large heat capacity is circulated as a coolant, have been widely used.

[0003] Water-cooled burner shutoff valves require two-way piping for circulating cooling water and a heat exchanger for dissipating heat from the recovered cooling water, which inevitably increases equipment costs. Furthermore, in a top-fired hot stove, the burners are located several tens of meters above the ground, and when using a water-cooled burner shutoff valve, cooling water must be pumped from the ground to the top of the furnace, which inevitably increases operating costs. Furthermore, in the case of a water-cooled burner shutoff valve, if the valve breaks, cooling water can leak into the furnace, causing extensive damage to the refractory bricks.

[0004] In response to this, a hot air valve with the same structure as an air-cooled burner shutoff valve that uses air as a refrigerant has been developed (see Patent Document 2). In particular, the hot air valve in Patent Document 2 has slits for ejecting cooling air on the surface of the valve seat where the valve plate is pressed, and the air from the slits flows along both the inner and outer side surfaces of the valve seat, ensuring cooling performance. In an air-cooled burner shutoff valve using this structure, it is easy to supply cooling air, and by releasing the cooled air into the atmosphere, the recovery piping can be omitted, which reduces equipment and operating costs compared to a water-cooled type. Furthermore, it reduces the possibility of damage to the firebricks in the event of valve breakage. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4955117 [Patent Document 2] Japanese Patent Application Publication No. 60-132191 Summary of the Invention [Problem to be solved by the invention]

[0006] In the air-cooled burner shutoff valve described above, the heat capacity of the air used as the coolant is smaller than that of water, so sufficient cooling air is required to obtain sufficient cooling capacity. Therefore, a large amount of high-pressure cooling air is supplied to the burner shutoff valve in addition to the combustion gas flowing from the burner to the combustion chamber. However, in order to supply a large amount of high-pressure cooling air, it is necessary to compress a large amount of air using a compressor, which makes it difficult to sufficiently reduce operating costs. In addition, if the cooling air that cooled the burner shutoff valve merged with the combustion gas passing through the burner shutoff valve, the air-fuel ratio of the combustion gas sent to the combustion chamber would increase, which could have lowered the temperature inside the hot stove.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an air-cooled burner shutoff valve which reduces operating costs. [Means for solving the problem]

[0008] The burner shut-off valve of the present invention is a burner shut-off valve that is installed in a combustion gas flow path leading from the burner of a hot stove to the combustion chamber, and has a valve plate that can advance into the combustion gas flow path to shut off the combustion gas flow path, a valve seat that is formed in a ring shape surrounding the combustion gas flow path and on which the valve plate can be seated, and an air outlet that is formed on the seating surface of the valve seat and blows out cooling air, and is characterized in that it has a bypass flow path that supplies air branched off from a combustion air pipe that supplies combustion air to the burner to the air outlet as the cooling air.

[0009] In the present invention, when the valve plate is retracted to open the combustion gas flow path, air from the combustion air pipe is supplied to the burner through the bypass flow path, where it is burned to become combustion gas, which is then supplied to the combustion chamber through the combustion gas flow path. On the other hand, by advancing the valve plate to block the combustion gas flow path, it is possible to prevent high heat from the combustion chamber from reaching the burner. In a burner shutoff valve, when shut off, the valve plate sits on the valve seat, and the valve plate blocks thermal radiation, preventing high heat from the combustion chamber from reaching the valve seat. The valve plate is also cooled by a separately provided cooling device. On the other hand, when open, the valve plate is retracted to the outside of the combustion gas flow path, and the valve seat is exposed to forced convection by the combustion gas passing through the combustion gas flow path. In response to this, the valve seat can be cooled by blowing cooling air from the air outlet of the valve seat. Here, the cooling air supplied from the air outlet is branched off from the combustion air pipe that supplies the combustion air to the burner, and the combustion air supplied to the burner is reduced accordingly. Then, when this cooling air is blown out from the air outlet and merges with the combustion gas from the burner, the total amount of air returns to the original amount of air in the combustion air pipe. Therefore, the total amount of air fed into the combustion chamber is the necessary and sufficient amount of air in the combustion chamber, preventing a drop in the furnace temperature that occurs when separate cooling air is supplied, and reducing the total amount of air used.

[0010] The burner shutoff valve of the present invention comprises a cooling air flow passage formed in the valve plate, and a valve plate cooling air supply device which supplies cooling air to the cooling air flow passage, the valve plate cooling air supply device having an air supply source, a high-pressure line which supplies air from the air supply source to the cooling air flow passage, and a low-pressure line which reduces the pressure of the air from the air supply source and supplies it to the cooling air flow passage, and it is preferable that the low-pressure line is opened under normal conditions and the high-pressure line is opened when the valve plate is damaged.

[0011] In the present invention, cooling air is normally supplied to the valve plate through a low-pressure line. The cooling air supplied through the low-pressure line is reduced in pressure below that of the air supply source by a pressure reducing valve or the like. As a result, the flow rate of the cooling air passing through the cooling air flow passage of the valve plate increases, and the cooling efficiency can be improved. Furthermore, when the low-pressure line is used, the amount of cooling air used is reduced, and a pressure increase process using a compressor or the like is not required, thereby reducing operating costs. On the other hand, when the valve plate is damaged, the high-temperature, high-pressure hot air from the combustion chamber flowing into the combustion gas flow path may flow into the cooling air flow path of the damaged valve plate and may backflow to the low-pressure line. In contrast, in the present invention, when damage to the valve plate is detected, the low-pressure line is shut off and valve plate cooling air from the high-pressure line is supplied to the cooling air flow path of the valve plate, thereby preventing the high-temperature, high-pressure hot air from the combustion gas flow path from flowing into the cooling air flow path of the valve plate. If the hot air flowing from the combustion chamber into the combustion gas flow path is, for example, 400 KPa, the pressure at the air supply source can be, for example, 540 KPa so that a higher pressure can be obtained in the higher pressure line, and the reduced pressure in the low pressure line can be, for example, 4 KPa.

[0012] In the burner shutoff valve of the present invention, it is preferable that the valve plate cooling air supply device has at least one of a temperature sensor that detects the temperature of the exhaust air from the cooling air flow path and a pressure sensor that detects the pressure at the valve plate side end of the low pressure line. In the present invention, when damage to the valve plate causes high-temperature, high-pressure hot air from the combustion chamber to flow through the combustion gas flow path into the cooling air flow path and the temperature of the air discharged from the cooling air flow path to rise, this can be detected by the temperature sensor, and when the high-temperature, high-pressure hot air that has flowed into the cooling air flow path further flows back into the low-pressure line, this can be detected by the pressure sensor. As a result, the valve plate cooling air supply device can detect damage to the valve plate and quickly and reliably switch between the low-pressure line and the high-pressure line. Effect of the Invention

[0013] According to the present invention, a burner shutoff valve that can reduce operating costs can be provided. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view showing a hot stove according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing the burner shutoff valve of the embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing the burner shutoff valve of the embodiment. [Figure 4] FIG. 4 is a front view showing the valve plate and the valve seat of the embodiment. [Diagram 5] FIG. 2 is a front view showing the piping system of the embodiment. [Figure 6] FIG. 4 is a front view showing a piping arrangement during a combustion operation according to the embodiment. [Figure 7] FIG. 4 is a front view showing piping settings during air blowing operation according to the embodiment. [Figure 8] FIG. 4 is a front view showing a piping arrangement when a valve plate is damaged according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a hot stove 1 is a top-combustion hot stove having a combustion chamber 20 above a heat regenerator 10. The heat regenerator 10 has a large amount of heat storage bricks 11 stacked inside. The heat storage bricks 11 are supported on a hearth 12, and a vent chamber 13 is formed at the bottom of the hearth. The vent chamber 13 is open to the atmosphere through a vent pipe 14. A shutoff valve, a blower, and other necessary devices are installed in the vent pipe 14.

[0016] A combustion tube 22, the inside of which is a combustion gas flow path 21, is connected to the combustion chamber 20. The other end of the combustion tube 22 is connected to a combustion air tube 23, and a burner 24 and a burner shutoff valve 25 are installed midway through the combustion tube 22. Although only one combustion tube 22 is shown in Figure 1, multiple combustion tubes 22 are arranged at equal intervals around the circumference of the combustion chamber 20 at the same height. A mixing chamber 33 is connected to the combustion chamber 20 near the heat storage chamber 10, and a hot air branch pipe 31 is connected to the lower end of the mixing chamber 33. The other end of the hot air branch pipe 31 is connected to a hot air main pipe 32, and a hot air valve 34 is installed midway along the hot air branch pipe 31.

[0017] The hot stove 1 is capable of performing combustion operation and air blowing operation under the unified control of each component by a control device (not shown).

[0018] When performing heat storage operation in the hot stove 1, the hot blast valve 34 of the hot blast branch pipe 31 is closed, the burner shutoff valve 25 of the combustion tube 22 is opened, and fuel is burned by the burner 24. As a result, the combustion air introduced from the combustion air pipe 23 is turned into high-temperature combustion gas by the burner 24, which is introduced from the combustion chamber 20 to the heat storage chamber 10, where it stores heat in the heat storage bricks 11, and is discharged outside the furnace from the vent pipe 14 (see the black arrow in Figure 1).

[0019] When performing air blowing operation in the hot stove 1, the hot air valve 34 of the hot air branch pipe 31 is opened, the burner 24 of the combustion tube 22 is stopped, the burner shutoff valve 25 is closed, and air is introduced from the vent pipe 14. As a result, the air is heated as it passes through the heat storage bricks 11, and hot air is supplied to the blast furnace from the hot air branch pipe 31 via the hot air main pipe 32 (see the white arrow in Figure 1).

[0020] 2 and 3, the burner shutoff valve 25 has a cylindrical valve body 41 that is incorporated in the middle of the combustion tube 22. The inside of the valve body 41 is made to be a part of the combustion gas flow path 21, and the combustion gas from the burner 24 to the combustion chamber 20 can pass through. A valve plate case 42 is formed on the upper side of the valve body 41, and a slit 411 is formed continuously from the inside of the valve plate case 42 to the inside of the valve body 41, and the valve plate 43 is housed in this slit 411.

[0021] 4, the valve plate 43 is formed in a disk shape and is capable of blocking the combustion gas flow path 21 inside the valve body 41. The valve plate 43 is raised and lowered by a drive mechanism (not shown), and is capable of moving from a blocking position where it is concentric with the combustion gas flow path 21 to an open position away from the combustion gas flow path 21. A cooling air flow path 431 is formed inside the valve plate 43, and a cooling air inlet 432 and a cooling air outlet 433 are formed at the upper end of the valve plate 43. The valve plate 43 can be cooled by passing cooling air through the cooling air flow path 431.

[0022] As shown in FIGS. 3 and 4, the valve body 41 is formed with a valve seat 44 . The valve seat 44 is an annular protrusion formed on the inner surface of the valve body 41 facing the valve plate 43 and surrounding the combustion gas flow path 21, and the seating surface at its tip is in close contact with the valve plate 43 over its entire circumference, thereby providing a full-circumference seal. A slit-shaped air outlet 441 is formed in the valve seat 44 at the tip where the valve plate 43 sits. When the valve plate 43 is not seated on the valve seat 44, the air outlet 441 is opened. If cooling air is supplied to the inside of the air outlet 441, the supplied cooling air is blown out from the valve seat 44 and can cool the seating surface at the tip of the valve seat 44.

[0023] In FIG. 5, the burner shutoff valve 25 is equipped with a valve seat cooling air supply device 50 that supplies cooling air to cool the valve seat 44, and a valve plate cooling air supply device 60 that supplies cooling air to cool the valve plate 43.

[0024] The valve seat cooling air supply device 50 has a bypass pipe 51 (bypass flow path) branching off from the combustion air pipe 23 that supplies combustion air to the burner 24. The other end of the bypass pipe 51 is connected to the air outlet 441 of the valve seat 44, and a flow rate adjustment valve 52 is installed midway. During combustion operation, when combustion air is being supplied from the combustion air pipe 23 to the burner 24, a portion of the combustion air flowing through the combustion air pipe 23 is branched off to the bypass pipe 51 and supplied to the air outlet 441 as cooling air. The amount of combustion air branched to the bypass pipe 51 can be adjusted by a flow rate control valve 52 .

[0025] The combustion air branched to the bypass pipe 51 is blown out from the air outlet 441 as cooling air to cool the valve seat 44, and then merges with the combustion gas from the burner 24 flowing through the combustion gas flow path 21. Therefore, the amount of combustion air in the combustion gas sent from the combustion gas flow path 21 to the combustion chamber 20 is always equal to the amount of combustion air supplied to the combustion air pipe 23 (the amount before branching), regardless of the amount branched to the bypass pipe 51.

[0026] During blowing operation, when combustion air is not being supplied from the combustion air pipe 23 to the burner 24, cooling air is not branched off at the bypass pipe 51 and supplied to the air outlet 441. During blowing operation, the valve plate 43 is seated on the valve seat 44, and the air outlet 441 formed on the seating surface is closed by the valve plate 43. Therefore, even if high-temperature, high-pressure hot air flows from the combustion chamber 20 into the combustion gas flow path 21 during blowing operation, it does not flow back into the valve seat cooling air supply device 50. In addition, by fully closing the flow rate adjustment valve 52, backflow into the valve seat cooling air supply device 50 can be prevented in addition.

[0027] The valve plate cooling air supply device 60 cools the valve plate 43 by circulating cooling air through the cooling air flow path 431. To this end, an air supply pipe 61 is connected to the cooling air inlet 432, and an air exhaust pipe 62 is connected to the cooling air exhaust port 433.

[0028] A low pressure line 63 and a high pressure line 64 are connected to the air supply pipe 61 via a switching valve 611. The low pressure line 63 and the high pressure line 64 are each connected to an air supply source 65 such as a compressed air tank. A flow rate adjustment valve 631 and a pressure reducing valve 632 are installed midway along the low pressure line 63, and high pressure air supplied from an air supply source 65 is reduced in pressure by the pressure reducing valve 632 so that it can be supplied to the air supply pipe 61 as low pressure air.

[0029] A flow rate adjustment valve 641 is installed midway along the high pressure line 64, so that the high pressure air supplied from the air supply source 65 can be supplied directly to the air supply pipe 61. Therefore, by switching between the low pressure line 63 and the high pressure line 64 using the switching valve 611, either low pressure air or high pressure air is supplied to the cooling air flow path 431 via the air supply pipe 61 or the cooling air inlet 432.

[0030] Here, the low-pressure cooling air supplied from the low-pressure line 63 has a lower pressure than the hot air passing through the combustion chamber 20 during blowing operation, and a higher pressure than the combustion gas sent from the burner 24 to the combustion gas flow path 21 during heat storage operation. Since the cooling air is at a low pressure, the flow rate in the cooling air passage 431 increases, and the cooling efficiency can be improved. On the other hand, the high-pressure cooling air supplied from the high-pressure line 64 is made sufficiently higher than the pressure in the combustion chamber 20 or the combustion gas passage 21.

[0031] A low pressure exhaust line 66 and a high pressure exhaust line 67 are connected to the air exhaust pipe 62 via a switching valve 621 . One end of the low pressure discharge line 66 is connected to the switching valve 621, and the other end is open to the atmosphere. One end of the high-pressure discharge line 67 is connected to the switching valve 621, a pressure reducing valve 671 is installed midway, and the other end is open to the atmosphere.

[0032] In the air supply pipe 61, when the switching valve 611 is switched to the low pressure line 63, low pressure cooling air is supplied to the cooling air flow path 431 of the valve plate 43, and the cooling air discharged from the air discharge pipe 62 is also at low pressure. Therefore, in the air discharge pipe 62, the switching valve 621 is switched to the low pressure discharge line 66, and the low pressure cooling air discharged from the air discharge pipe 62 may be discharged directly into the atmosphere. When the switching valve 611 is switched to the high pressure line 64, high pressure cooling air is supplied to the cooling air passage 431 of the valve plate 43, and the cooling air discharged from the air discharge pipe 62 is also at high pressure. Therefore, in the air discharge pipe 62, the switching valve 621 is switched to the high pressure discharge line 67, and the high pressure cooling air discharged from the air discharge pipe 62 passes through a pressure reducing valve 671 and is discharged into the atmosphere. Here, by setting the pressure of the pressure reducing valve 671 to be higher than the pressure in the combustion chamber 20 or the combustion gas passage 21, it is possible to keep the pressure in the cooling air passage 431 higher than the hot air flowing from the combustion chamber 20 into the combustion gas passage 21.

[0033] In the valve plate cooling air supply device 60, the switching of the switching valves 611, 621 is controlled by a control device (not shown) of the hot stove 1. During the control, measurement values ​​from sensors installed at various parts of the piping are referenced. A temperature sensor 612 is installed midway along the air supply pipe 61 . A temperature sensor 622 is installed midway along the air exhaust pipe 62 . In the low pressure line 63 , a pressure sensor 633 is installed between the flow rate adjustment valve 631 and the pressure reducing valve 632 , and a pressure sensor 634 is installed between the flow rate adjustment valve 631 and the switching valve 611 . A pressure sensor 642 is installed in the high pressure line 64 between the flow rate adjustment valve 641 and the air supply source 65 .

[0034] In the valve plate cooling air supply device 60, the low pressure line 63 and the low pressure exhaust line 66 are normally opened to allow low pressure cooling air to flow through the cooling air passage 431. When the valve plate 43 is damaged, the high pressure line 64 and the high pressure exhaust line 67 are switched to circulate high pressure cooling air through the cooling air passage 431 . The valve plate 43 is deemed to be damaged when the temperature of the exhaust air from the cooling air flow path 431 detected by the temperature sensor 622 becomes higher than a specified value, or when the pressure at the valve plate 43 end of the low pressure line 63 detected by the pressure sensor 634 becomes higher than a preset value.

[0035] In this embodiment, during the combustion operation and the blowing operation of the hot stove 1, cooling air is supplied from the valve seat cooling air supply device 50 and the valve plate cooling air supply device 60 depending on the situation.

[0036] 6, during combustion operation of the hot stove 1, the burner shutoff valve 25 is opened and the valve plate 43 is retracted from the combustion gas flow path 21. In this state, the lower part of the valve plate 43 is exposed to high-temperature combustion gas from the burner 24 passing through the combustion gas flow path 21 and becomes hot, so cooling air is supplied from the valve plate cooling air supply device 60 to cool the valve plate 43. On the other hand, since the valve seat 44 is exposed to high-temperature combustion gas from the burner 24 passing through the combustion gas flow path 21, cooling air is supplied from the valve seat cooling air supply device 50 (shown by a solid line in the figure).

[0037] 7, during the blowing operation of the hot stove 1, the burner shutoff valve 25 is closed and the combustion gas flow path 21 is shut off by the valve plate 43. In this state, the air outlet 441 is closed by the valve plate 43 and cooling of the valve seat 44 by the valve seat cooling air supply device 50 is stopped. On the other hand, the valve plate 43 becomes hot due to exposure to radiant heat and hot air from the combustion chamber 20, so cooling air is supplied from the valve plate cooling air supply device 60 to cool the valve plate 43. During normal blowing operation, the valve plate cooling air supply device 60 opens the low pressure line 63 and the low pressure exhaust line 66 to circulate low pressure cooling air through the cooling air passage 431 (shown by solid lines in the figure). In this state, the high pressure line 64 and the high pressure exhaust line 67 are blocked (shown by dotted lines in the figure).

[0038] If damage occurs to the valve plate 43 during blowing operation and the cooling air flow path 431 and the combustion gas flow path 21 become connected, high-temperature, high-pressure hot air from the combustion chamber 20 may flow into the cooling air flow path 431 through which low-pressure cooling air is passing, and may then pass through the air supply pipe 61 and air exhaust pipe 62 and reach the low-pressure line 63 and low-pressure exhaust line 66. In such a situation, a pressure increase in the low pressure line 63 is detected by the pressure sensor 634, or a temperature increase in the air exhaust pipe 62 is detected by the temperature sensor 622.

[0039] In Figure 8, when damage to the valve plate 43 is detected during blowing operation, the valve plate cooling air supply device 60 switches the switching valves 611, 621 to block the low pressure line 63 and the low pressure exhaust line 66 (shown by dotted lines in the figure), and instead opens the high pressure line 64 and the high pressure exhaust line 67, allowing high pressure cooling air to circulate through the cooling air flow path 431 (shown by solid lines in the figure). As a result, high-pressure cooling air flows through the cooling air passage 431 of the valve plate 43, preventing the inflow of high-temperature, high-pressure gas from the damaged portion, and cooling of the valve plate 43 continues.

[0040] According to this embodiment, the following effects can be obtained. In this embodiment, when the valve plate 43 of the burner shutoff valve 25 is retracted to open the combustion gas flow path 21, air from the combustion air pipe 23 is supplied to the burner 24 by the bypass pipe 51, and is converted into combustion gas by combustion in the burner 24 and supplied to the combustion chamber 20 through the combustion gas flow path 21. On the other hand, by advancing the valve plate 43 to shut off the combustion gas flow path 21, it is possible to prevent the high heat from the combustion chamber 20 from reaching the burner 24. In the burner shutoff valve 25, when shut off, the valve plate 43 sits on the valve seat 44, and the valve plate 43 blocks thermal radiation, thereby preventing high heat from the combustion chamber 20 from reaching the valve seat 44. The valve plate 43 is also cooled by a separately formed cooling device. On the other hand, when open, the valve plate 43 is retracted to the outside of the combustion gas flow path 21, and the valve seat 44 is exposed to forced convection by the combustion gas passing through the combustion gas flow path 21. In response to this, the valve seat 44 can be cooled by blowing cooling air from the air outlet 441 of the valve seat 44. Here, the cooling air supplied from the air outlet 441 is branched off from the combustion air pipe 23 which supplies the combustion air to the burner 24, and the combustion air supplied to the burner 24 is reduced accordingly. Then, when this cooling air is blown out from the air outlet 441 and merges with the combustion gas from the burner 24, the total amount of air becomes the original amount of air in the combustion air pipe 23. Therefore, the total amount of air fed into the combustion chamber 20 is the necessary and sufficient amount of air for the combustion chamber 20, preventing a drop in the furnace temperature that occurs when separate cooling air is supplied, and reducing the total amount of air used.

[0041] In this embodiment, cooling air is normally supplied to the valve plate 43 through the low-pressure line 63. The cooling air supplied through the low-pressure line 63 is reduced in pressure by the pressure reducing valve 632 to a pressure lower than that at the air supply source 65. As a result, the flow rate of the cooling air passing through the cooling air passage 431 of the valve plate 43 increases, and the cooling efficiency can be improved. Furthermore, when the low-pressure line 63 is used, the amount of cooling air used is reduced, and a pressure increase process using a compressor or the like is not required, thereby reducing operating costs. On the other hand, when the valve plate 43 is damaged, high-temperature, high-pressure hot air from the combustion chamber 20 may flow into the cooling air flow passage 431 of the valve plate 43 and may flow back to the low-pressure line 63. In response to this, when damage to the valve plate 43 is detected, the low-pressure line 63 is shut off and valve plate cooling air from the high-pressure line 64 is supplied to the cooling air flow passage 431 of the valve plate 43, thereby preventing the high-temperature, high-pressure gas from the combustion gas flow passage 21 from flowing into the cooling air flow passage 431 of the valve plate 43. If the hot air from the combustion chamber 20 is, for example, 400 KPa, the pressure at the air supply source 65 can be, for example, 540 KPa so that a higher pressure can be obtained at the high pressure line 64, and the reduced pressure at the low pressure line 63 can be, for example, 4 KPa.

[0042] In this embodiment, when damage to the valve plate 43 causes high-temperature, high-pressure hot air flowing from the combustion chamber 20 into the combustion gas flow path 21 to flow from the damaged part into the cooling air flow path 431 and the temperature of the exhaust air from the cooling air flow path 431 to rise, this can be detected by the temperature sensor 622, and when the high-temperature, high-pressure gas that has flowed into the cooling air flow path 431 further flows back into the low-pressure line 63, this can be detected by the pressure sensor 634. As a result, the valve plate cooling air supply device 60 can detect damage to the valve plate 43 and quickly and reliably switch between the low-pressure line 63 and the high-pressure line 64.

[0043] The present invention is not limited to the above-described embodiment, and modifications within the scope of the present invention are included in the present invention. In the valve plate cooling air supply device 60, the low pressure line 63 and the high pressure line 64 are connected to the same air supply source 65, but they may be separate. For example, a low pressure air supply source may be connected to the low pressure line 63, and a high pressure air supply source may be connected to the high pressure line 64. In this case, the pressure reducing valve 632 of the low pressure line 63 can be omitted. In the high-pressure exhaust line 67, a pressure reducing valve 671 is installed to keep the pressure in the cooling air passage 431 higher than the pressure in the combustion chamber 20 or the combustion gas passage 21, but the pressure may be adjusted using a pressure regulating valve or other equipment.

[0044] In the valve plate cooling air supply device 60, damage to the valve plate 43 can be detected not only by the temperature sensor 622 of the air exhaust pipe 62 and the pressure sensor 634 of the low pressure line 63, but also by the pressure sensor 633 of the low pressure line 63 and the temperature sensor 612 of the air supply pipe 61. However, since cooling air basically flows through the air supply pipe 61 toward the valve plate 43, there is a possibility that the arrival of the high-temperature, high-pressure fluid that has flowed into the cooling air flow passage 431 may be delayed. The pressure sensor 642 in the high-pressure line 64 is not suitable for detecting damage since the high-pressure line 64 is normally disconnected from the air supply pipe 61.

[0045] The details of the configuration of burner shutoff valve 25, such as the shape of valve seat 44, the shape or arrangement of air outlet 441, the shape of valve plate 43, and the shape or arrangement of cooling air passage 431, may be modified as appropriate. [Industrial Applicability]

[0046] The present invention can be used in burner shutoff valves. [Explanation of symbols]

[0047] 1...hot air furnace, 10...heat storage chamber, 11...heat storage brick, 12...furnace bed, 13...ventilation chamber, 14...ventilation pipe, 20...combustion chamber, 21...combustion gas flow path, 22...combustion tube, 23...combustion air pipe, 24...burner, 25...burner shutoff valve, 31...hot air branch pipe, 32...hot air main pipe, 33...mixing chamber, 34...hot air valve, 41...valve body, 411...slit, 42...valve plate case, 43...valve plate, 431...cooling air flow path, 432...cooling air inlet, 433...cooling air outlet, 44...valve seat, 441...air outlet, 50 ...valve seat cooling air supply device, 51...bypass pipe, 52...flow control valve, 60...valve plate cooling air supply device, 61...air supply pipe, 611...switching valve, 612...temperature sensor, 62...air exhaust pipe, 621...switching valve, 622...temperature sensor, 63...low pressure line, 631...flow control valve, 632...pressure reducing valve, 633...pressure sensor, 634...pressure sensor, 64...high pressure line, 641...flow control valve, 642...pressure sensor, 65...air supply source, 66...low pressure exhaust line, 67...high pressure exhaust line, 671...pressure reducing valve.

Claims

1. A burner shutoff valve is provided in a combustion gas flow path from a burner of a hot stove to a combustion chamber, the burner shutoff valve having a valve plate that can advance into the combustion gas flow path to shut off the combustion gas flow path, a valve seat that is formed in an annular shape surrounding the combustion gas flow path and on which the valve plate can be seated, and an air outlet that is formed on a seating surface of the valve seat and that blows out cooling air, a bypass flow path for supplying air branched from a combustion air pipe for supplying combustion air to the burner to the air outlet as the cooling air, A burner shutoff valve, characterized in that the cooling air blown out from the air outlet joins the combustion gas from the burner flowing through the combustion gas flow path.

2. 2. The burner shutoff valve of claim 1, a valve plate cooling air supply device that supplies cooling air to the cooling air flow path, The valve plate cooling air supply device has an air supply source, a high-pressure line that supplies air from the air supply source to the cooling air flow path, and a low-pressure line that reduces the pressure of the air from the air supply source and supplies it to the cooling air flow path, and is characterized in that the low-pressure line is opened under normal conditions, and the high-pressure line is opened when the valve plate is damaged.

3. 3. The burner shutoff valve according to claim 2, The valve plate cooling air supply device is characterized in having at least one of a temperature sensor that detects the temperature of the exhaust air from the cooling air flow path and a pressure sensor that detects the pressure at the valve plate side end of the low pressure line.

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