Self-ignition prevention device

Abstract

To suppress increase in component cost and maintenance cost and also properly suppress self-ignition of an inflammable gas in a self-ignition prevention device.SOLUTION: A self-ignition prevention device includes: piping capable of being filled with an inflammable gas and communicated to an object area; an expanded pipe installed between the piping and the object area and having an internal diameter that is larger than an internal diameter of the piping; and a jetting part for jetting the inflammable gas toward a center part side from an outer peripheral part of the expanded pipe.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a spontaneous ignition prevention device that prevents spontaneous ignition of flammable gas in a pipe. [Background technology]

[0002] For example, in waste incinerators, integrated coal gasification combined cycle (IGCC) plants, power generation boilers, etc., dust contained in the exhaust gas adheres to the inner walls of the furnace and the outer surfaces of the heat transfer tubes, etc. Dust that adheres to the inner walls of the furnace and the outer surfaces of the heat transfer tubes reduces the heat transfer coefficient, worsening the heat recovery efficiency, and acts as resistance to the flow of exhaust gas, reducing the performance of the furnace.

[0003] An example of a device for removing dust adhering to the inner wall of a furnace or the outer surface of a heat transfer tube is described in the following Patent Document 1. The dust removal device described in Patent Document 1 fills flammable gas into a pipe communicating with the inside of the furnace, and generates a shock wave by detonation when the flammable gas is ignited. With this dust removal device, the shock wave acts on the inner wall surface of the furnace or the outer surface of the heat transfer tube, thereby blowing off and removing the adhering dust. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2005 / 0126594 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional dust removal devices have multiple gate valves arranged in the piping, and when not in operation, the gate valves are moved to a closed position to prevent spontaneous ignition of the flammable gas filled in the piping. However, if the inner diameter of the piping is large, the valves become large, which creates a problem in that the parts cost and maintenance cost increase. In addition, since the gate valves are arranged in a high-temperature environment, there is a risk of malfunction, making it difficult to appropriately prevent spontaneous ignition of the flammable gas.

[0006] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a self-ignition prevention device that suppresses increases in parts costs and maintenance costs and appropriately suppresses the self-ignition of flammable gas. [Means for solving the problem]

[0007] In order to achieve the above object, the self-ignition prevention device of the present disclosure includes a pipe that can be filled with a flammable gas and can be connected to a target area, an expansion pipe that is provided between the pipe and the target area and has an inner diameter larger than the inner diameter of the pipe, and an ejection part that ejects non-flammable gas from an outer periphery of the expansion pipe toward a center side. Effect of the Invention

[0008] According to the self-ignition prevention device of the present disclosure, it is possible to suppress increases in parts costs and maintenance costs, and also to appropriately suppress the self-ignition of flammable gas. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a furnace illustrating a self-ignition prevention device according to a first embodiment. [Diagram 2] FIG. 2 is a front view of the self-ignition prevention device as viewed from the furnace side. [Diagram 3] FIG. 3 is a cross-sectional view of a furnace illustrating the self-ignition prevention device of the second embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a furnace illustrating the auto-ignition prevention device of the third embodiment. [Diagram 5]FIG. 5 is a front view of the self-ignition prevention device as viewed from the furnace side. [Figure 6] FIG. 6 is a cross-sectional view of a furnace illustrating a self-ignition prevention device according to the fourth embodiment. [Figure 7] FIG. 7 is a cross-sectional view of a furnace illustrating the auto-ignition prevention device of the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0011] [First embodiment] <Configuration of the self-ignition prevention device> FIG. 1 is a cross-sectional view of a furnace illustrating the self-ignition prevention device of the first embodiment, and FIG. 2 is a front view of the self-ignition prevention device from the furnace side.

[0012] The spontaneous ignition prevention device of the first embodiment is applied to a dust removal device that removes dust adhering to the inner wall surface and the outer surface of a heat transfer tube of a furnace such as a waste incinerator, an integrated coal gasification combined cycle power generation facility, or a power generation boiler (hereinafter referred to as a boiler). The dust removal device supplies combustible gas into the furnace through a pipe that communicates with the inside of the furnace, and generates a shock wave by detonation by igniting the combustible gas. The dust removal device blows away and removes the adhering dust by the shock wave caused by the detonation acting on the inner wall of the furnace and the outer surface of the heat transfer tube.

[0013] The spontaneous ignition prevention device is provided in the dust removal device and prevents spontaneous ignition of flammable gas filled in the piping due to the heat of exhaust gas rising inside the furnace while the boiler is in operation.

[0014] As shown in FIGS. 1 and 2, the self-ignition prevention device 10 includes a pipe 11, an expansion pipe 12, and an ejection part 13.

[0015] The furnace 101 has a furnace wall 102. The furnace 101 has an internal space 103 partitioned by an inner wall surface 102a of the furnace wall 102. In the internal space 103 of the furnace 101, a heat transfer tube constituting a heat exchanger (not shown) is arranged. In the internal space 103 of the furnace 101, high-temperature exhaust gas G1 flows in a predetermined direction. The flow direction of the high-temperature exhaust gas G1 varies depending on the position of the internal space 103, the surrounding shape, etc., but the following describes a case where the high-temperature exhaust gas G1 rises in the internal space 103.

[0016] The pipe 11 is capable of supplying the flammable gas G2 to the internal space 103, which is the target area. The pipe 11 is, for example, cylindrical in shape, and has the same inner diameter in the longitudinal direction. However, the pipe 11 is not limited to a cylindrical shape, and may be a polygonal tubular shape. A supply device (not shown) for the flammable gas G2 is connected to one axial end of the pipe 11, and a diffuser 12 is connected to the other end.

[0017] The diffuser 12 is provided between the pipe 11 and the furnace wall 102 (internal space 103) of the furnace 101. The inner diameter of the diffuser 12 on the furnace wall 102 side is larger than the inner diameter of the pipe 11. The diffuser 12 expands continuously and uniformly from the pipe 11 side toward the furnace wall 102 (internal space 103) side. That is, one end of the diffuser 12 in the axial direction has the same diameter as the pipe 11, and is connected to the other end of the pipe 11. The diffuser 12 gradually expands in diameter from one end to the other end in the axial direction, and is connected to the furnace wall 102. Note that the diffuser 12 is subjected to a recoil due to a shock wave caused by the explosion of the combustible gas G2 inside the diffuser 12, so the connection part of the diffuser 12 to the furnace wall 102 may be made movable.

[0018] The blowout part 13 blows out the noncombustible gas G3 from the outer periphery toward the center of the diffuser 12. The blowout part 13 is provided on the other end side of the diffuser 12, that is, on the furnace 101 (internal space 103) side.

[0019] An outer cylinder pipe 21 is disposed on the outside of the other end side of the diffuser 12. The outer cylinder pipe 21 has a cylindrical shape with a larger diameter than the diffuser 12, and expands uniformly from one end to the other end in the axial direction, similar to the diffuser 12. The inner peripheral surface of the outer cylinder pipe 21 is disposed with a gap from the outer peripheral surface of the diffuser 12, and the outer peripheral surface is fitted and fixed in the through hole 102b of the furnace wall 102. Therefore, the other end side of the diffuser 12 is disposed inside the furnace wall 102, and the entire outer cylinder pipe 21 is disposed inside the furnace wall 102. The outer cylinder pipe 21 may also be connected to the furnace wall 102 so as to be freely movable, similar to the diffuser 12.

[0020] The outer cylinder pipe 21 has an outer cylinder portion 21a and a flange portion 21b. The outer cylinder portion 21a is disposed with a gap from the outer peripheral surface of the diffuser pipe 12. The flange portion 21b is disposed on the other axial end side of the outer cylinder pipe 21, with its outer peripheral portion connected to the other end of the outer cylinder portion 21a and its inner peripheral portion connected to the other end of the diffuser pipe 12. Therefore, a cylindrical gas flow portion 22 is formed between the diffuser pipe 12 and the outer cylinder pipe 21.

[0021] The header 23 is disposed on one end of the outer cylinder pipe 21 in the axial direction. The header 23 is ring-shaped and has an L-shaped cross section. One end of the header 23 in the width direction is fixed to the outer wall surface 102c of the furnace wall 102, and the other end is fixed to the outer circumferential surface of the diffuser 12. Therefore, the header 23 defines a ring-shaped gas space 24 between the furnace wall 102 and the diffuser 12. The gas space 24 communicates with one end of the gas flow section 22. The header 23 may be connected to the furnace wall 102 in a freely movable manner, like the diffuser 12 and the outer cylinder pipe 21. The header 23 may be fixed to the outer cylinder pipe 21 to define the gas space 24.

[0022] The ejection part 13 has a plurality of ejection holes 31 (eight in this embodiment) that eject the non-combustible gas G3. The plurality of ejection holes 31 are formed on the other axial end side of the diffuser 12, that is, on the inner space 103 side of the furnace 101. The plurality of ejection holes 31 are slit-shaped openings along the circumferential direction of the diffuser 12. However, the number of the ejection holes 31 is not limited. Moreover, the ejection holes 31 are not limited to being slit-shaped, and may be circular holes.

[0023] The multiple ejection holes 31 constituting the ejection part 13 eject the noncombustible gas G3 in an inclined direction inclined toward the internal space 103 of the furnace 101 with respect to the radial direction of the diverter 12. That is, the diverter 12 expands in diameter from one end toward the other end. The multiple ejection holes 31 are holes penetrating in a direction perpendicular to the other end of the diverter 12 that expands in diameter. Therefore, the multiple ejection holes 31 eject the noncombustible gas G3 from the outer periphery of the diverter 12 toward the internal space 103.

[0024] The diffuser 12 is set to a preset expansion ratio. For example, when the inner diameter of one end of the diffuser 12 is R1 and the inner diameter of the other end of the diffuser 12 is R2, the area ratio is (R2 / 2) 2 π / (R1 / 2) 2 It is preferable to set π=1.4 to 4.0. It is also preferable to set the angle α of the inner surface of the diffuser 12 with respect to the center line to be 10 degrees to 50 degrees. It is also preferable to set the ejection angle β of the non-flammable gas G3 of the ejection hole 31 with respect to the radial direction of the diffuser 12 to be 0 degrees to 45 degrees.

[0025] One end of a gas supply line 26 is connected to the header 23 via a port 25. A gas supply source 27 is connected to the other end of the gas supply line 26, and an on-off valve 28 is provided in the middle of the line. Here, the gas supply source 27 is, for example, a blower or a compressor, and supplies air or compressed air as the non-flammable gas G3. However, the gas supply source 27 is not limited to this configuration. For example, the non-flammable gas G3 may be a gas having a lower oxygen fraction than air or an inert gas (such as nitrogen or argon) instead of air, and the gas supply source 27 may be a tank for storing such a gas.

[0026] Therefore, when the on-off valve 28 is opened, the noncombustible gas G3 is supplied from the gas supply source 27 to the gas supply line 26, and is supplied to the gas space portion 24 via the port 25. The noncombustible gas G3 supplied to the gas space portion 24 flows through the gas flow portion 22 to the other end side of the expanding pipe 12, and is sprayed from the multiple spray holes 31 to the center side of the expanding pipe 12.

[0027] <Function of the self-ignition prevention device> In the furnace 101, when dust adheres to the inner wall surface 102a of the furnace wall 102 or the heat transfer tube (not shown) of the heat exchanger due to long-term use, the dust removal device is operated. That is, the combustible gas G2 is supplied to the pipe 11 by the supply device to fill it, and the combustible gas G2 is ignited. Then, the combustible gas G2 burns inside the pipe 11 and generates a shock wave due to detonation. The generated shock wave is transmitted to the internal space 103 through the pipe 11 and the expansion tube 12, and acts on the inner wall surface 102a of the furnace wall 102 and the outer surface of the heat transfer tube, and the attached dust is blown off and removed. At this time, the shock wave due to the detonation generated in the pipe 11 is transmitted to the internal space 103 of the furnace 101 through the expanding expansion tube 12, so that the supersonic flow ejected together with the blast can be expanded at an appropriate area ratio to efficiently introduce the blast and jet into the internal space 103. When the dust removing device has removed the dust adhering to the inner wall surface 102a of the furnace wall 102 and the outer surfaces of the heat transfer tubes, the operation of the dust removing device is stopped.

[0028] When the dust removal device described above removes dust, the combustible gas G2 filled inside the pipe 11 and the diffuser 12 may spontaneously ignite. Therefore, when the dust removal device is in operation, the spontaneous ignition prevention device 10 is operated. That is, the on-off valve 28 is opened, and the non-combustible gas G3 is supplied from the gas supply source 27 to the gas space 24 through the gas supply line 26. Then, the non-combustible gas G3 filled in the gas space 24 flows through the gas flow section 22 to the other end side of the diffuser 12, and is ejected from the multiple ejection holes 31 toward the center side of the diffuser 12.

[0029] At this time, the blowing part 13 blows out the non-combustible gas G3 from the multiple blowing holes 31 toward the center of the diverter 12, thereby forming an air curtain between the inside of the diverter 12 and the internal space 103 of the furnace 101. The air curtain of the non-combustible gas G3 separates the inside of the diverter 12 from the internal space 103, so that, for example, the rising exhaust gas G1 is prevented from penetrating the internal space 103 into the inside of the diverter 12. Therefore, spontaneous ignition of the combustible gas G2 filled in the piping 11 due to contact with the high-temperature exhaust gas G1 is prevented.

[0030] However, due to the flow velocity or drift of the exhaust gas G1 rising in the internal space 103, a part of the exhaust gas G1 may slip through the air curtain of the non-combustible gas G3 and infiltrate into the diffuser 12. At this time, since the inner diameter (area) of the diffuser 12 on the furnace wall 102 side is larger than that on the piping 11 side, the exhaust gas G1 that infiltrates into the diffuser 12 from the internal space 103 becomes a secondary flow F that swirls counterclockwise in FIG. 1 inside the diffuser 12. Therefore, the exhaust gas G1 that infiltrates into the diffuser 12 becomes the secondary flow F and swirls and stagnates inside the diffuser 12, making it difficult to flow toward the piping 11 side, and the spontaneous ignition of the combustible gas G2 filled in the piping 11 is suppressed.

[0031] Even if a part of the exhaust gas G1 that has entered the diffuser 12 comes into contact with the combustible gas G2 filled in the piping 11, the temperature of the exhaust gas G1 drops while it flows through the diffuser 12. That is, the combustible gas G2 in the piping 11 is mixed with the exhaust gas G1 whose temperature has been lowered, diluted, and the concentration of the combustible gas G2 in the piping 11 drops without spontaneous ignition. Therefore, even if the mixed gas of the combustible gas G2 and the exhaust gas G1 returns to the internal space 103 through the diffuser 12, spontaneous ignition of the combustible gas G2 is suppressed.

[0032] In the above description, the auto-ignition prevention device 10 is configured to operate when dust adhering to the inner wall surface 102a of the furnace wall 102 or the outer surface of the heat transfer tube is removed by the dust removal device, but the configuration is not limited to this. The auto-ignition prevention device 10 may be kept in operation at all times.

[0033] [Second embodiment] 3 is a cross-sectional view of a furnace showing a self-ignition prevention device according to a second embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed description thereof will be omitted.

[0034] In the second embodiment, as shown in FIG. 3, a self-ignition prevention device 10A includes a pipe 11, an expansion pipe 12, and an ejection part 13A.

[0035] The diverter 12 is provided between the pipe 11 and the internal space 103 of the furnace 101. One end of the diverter 12 has the same diameter as the pipe 11, is connected to the other end of the pipe 11, and the diameter gradually increases toward the other end, and is connected to the furnace wall 102. The blowout section 13A blows out the non-combustible gases G3 and G4 from the outer periphery of the diverter 12 toward the center. The blowout section 13 has a plurality of first blowout holes 31 and a plurality of second blowout holes 32. The first blowout holes 31 are provided on the furnace 101 (internal space 103) side of the diverter 12, and blow out the non-combustible gas G3. The second blowout holes 32 are provided on the diverter 12 on the pipe 11 side, and blow out the non-combustible gas G4. The first and second nozzles 31 and 32 constituting the nozzle section 13 jet out the non-combustible gas G3 in a direction inclined toward the inner space 103 of the furnace 101 with respect to the radial direction of the diffuser 12.

[0036] An outer cylinder pipe 21 is disposed on the outside of the other end of the diverter pipe 12, and a cylindrical gas flow section 22 is formed between the diverter pipe 12 and the outer cylinder pipe 21. A header 23 is disposed on one axial end of the outer cylinder pipe 21. The header 23 defines a gas space section 24 that communicates with the gas flow section 22 and the second ejection holes 32. One end of a gas supply line 26 is connected to the header 23 via a port 25. A gas supply source 27 is connected to the other end of the gas supply line 26, and an opening / closing valve 28 is provided midway.

[0037] Therefore, when the self-ignition prevention device 10 is operated, the non-flammable gas G3 is supplied from the gas supply line 26 to the gas space 24 and is ejected from the multiple second ejection holes 32 toward the center of the expander 12. The non-flammable gas G3 also flows from the gas space 24 through the gas flow section 22 toward the other end of the expander 12 and is ejected from the multiple first ejection holes 31 toward the center of the expander 12.

[0038] At this time, the first nozzle 31 ejects the non-combustible gas G3 toward the center at the other end of the diffuser 12, forming an air curtain between the inside of the diffuser 12 and the internal space 103 of the furnace 101. Also, the second nozzle 32 ejects the non-combustible gas G4 toward the center at one end of the diffuser 12, forming an air curtain between the inside of the diffuser 12 and the inside of the piping 11. The two air curtains of the non-combustible gas G3 separate the inside of the piping 11, the inside of the diffuser 12, and the internal space 103. The air curtain of the non-combustible gas G3 separates the inside of the diffuser 12 from the internal space 103. Also, the air curtain of the non-combustible gas G4 separates the inside of the piping 11 from the internal space 103. Then, the air curtain of the non-combustible gas G3 prevents the exhaust gas G1 rising in the internal space 103 from penetrating into the inside of the diffuser 12. In addition, the air curtain of the non-combustible gas G4 prevents the flammable gas G2 in the pipe 11 from penetrating into the diffuser 12. Therefore, spontaneous ignition of the flammable gas G2 filled in the pipe 11 by the exhaust gas G1 is prevented.

[0039] In the above description, the first ejection hole 31 and the second ejection hole 32 are provided as the ejection part 13, but the present invention is not limited to this configuration. For example, the ejection part 13 may be configured with only the second ejection hole 32.

[0040] [Third embodiment] Fig. 4 is a cross-sectional view of a furnace showing the self-ignition prevention device of the third embodiment, and Fig. 5 is a front view of the self-ignition prevention device from the furnace side. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed explanations are omitted.

[0041] In the third embodiment, as shown in FIGS. 4 and 5, a self-ignition prevention device 10B includes a pipe 11, an expansion pipe 12, and an ejection part 13B.

[0042] The diverging pipe 12 is provided between the pipe 11 and the internal space 103 of the furnace 101. One end of the diverging pipe 12 has the same diameter as the pipe 11, is connected to the other end of the pipe 11, and the diameter gradually increases toward the other end, and is connected to the furnace wall 102. The ejection section 13B ejects noncombustible gases G3a and G3b from the outer periphery of the diverging pipe 12 toward the center. The ejection section 13B has a plurality of upstream ejection holes (upstream ejection section) 31a and a plurality of downstream ejection holes (downstream ejection section) 31b. The upstream ejection holes 31a and the downstream ejection holes 31b are provided on the furnace 101 side of the diverging pipe 12, and eject the noncombustible gases G3a and G3b, respectively.

[0043] The upstream nozzle 31a is disposed on the upstream side (lower side in FIG. 4) of the flow direction of the exhaust gas G1 ascending in the internal space 103 of the furnace 101. The downstream nozzle 31b is disposed on the downstream side (upper side in FIG. 4) of the flow direction of the exhaust gas G1 ascending in the internal space 103 of the furnace 101. In this embodiment, the upstream nozzle 31a is disposed on the lower side of the diffuser 12 by four, and the downstream nozzle 31b is disposed on the upper side of the diffuser 12 by four, but the numbers are not limited and do not have to be the same. The amount of non-combustible gas G3b emitted from the downstream nozzle 31b is greater than the amount of non-combustible gas G3a emitted from the upstream nozzle 31a. Specifically, it is preferable that the deviation of the dynamic pressure of the air curtain, which is the deviation of the flow rates of the non-combustible gases G3a and G3b, is set to, for example, 0.5 times or more of the dynamic pressure of the exhaust gas G1 ascending in the internal space 103.

[0044] An outer cylinder pipe 21 is disposed on the outside of the other end of the diffuser pipe 12, and cylindrical gas flow sections 22a, 22b are formed between the diffuser pipe 12 and the outer cylinder pipe 21. Partition plates 21c are provided on the inner surfaces of both horizontal sides of the outer cylinder pipe 21, dividing the lower gas flow section 22a and the upper gas flow section 22b. A header 23 is provided on one end of the outer cylinder pipe 21 in the axial direction. The header 23 divides gas spaces 24a, 24b that communicate with the gas flow sections 22a, 22b. Partition plates (not shown) are provided on the inner surfaces of both horizontal sides of the header 23, dividing the lower gas space section 24a and the upper gas space section 24b. The gas flow section 22a communicates with the gas space section 24a, and the gas flow section 22b communicates with the gas space section 24b. One end of a gas supply line 26a is connected to the header 23 via a port 25a communicating with the gas space portion 24a, and the other end is connected to a gas supply source 27. One end of a gas supply line 26b is connected to the header 23 via a port 25b communicating with the gas space portion 24b, and the other end is connected to the gas supply source 27. Open / close valves 28a and 28b are provided in the middle of the gas supply lines 26a and 26b. The open / close valves 28a and 28b are flow rate regulating valves.

[0045] Therefore, when the self-ignition prevention device 10 is operated, the non-flammable gases G3a, G3b are supplied from the gas supply lines 26a, 26b to the gas spaces 24a, 24b, and flow through the gas flow sections 22a, 22b to the other end side of the expanding tube 12. Then, the non-flammable gas G3a is ejected toward the center side of the expanding tube 12 from the multiple upstream side ejection holes 31a, and the non-flammable gas G3b is ejected toward the center side of the expanding tube 12 from the multiple downstream side ejection holes 31b.

[0046] That is, the upstream nozzle 31a ejects the non-combustible gas G3a along the exhaust gas G1 ascending in the internal space 103, and the downstream nozzle 31b ejects the non-combustible gas G3a opposite to the exhaust gas G1 ascending in the internal space 103. At this time, the opening of the on-off valves 28a, 28b is adjusted so that the amount of non-combustible gas G3b ejected from the downstream nozzle 31b is made greater than the amount of non-combustible gas G3a ejected from the upstream nozzle 31a.

[0047] Due to flow velocity and drift, some of the exhaust gas G1 rising in the internal space 103 may slip through the air curtain of the non-combustible gas G3 and enter the diffuser 12. The exhaust gas G1 that enters the diffuser 12 from the internal space 103 becomes a secondary flow F that swirls counterclockwise in FIG. 4 in the diffuser 12. Here, the downstream nozzle 31b ejects a large amount of non-combustible gas G3b so as to face the flow of the exhaust gas G1 entering the diffuser 12 from the internal space 103. Therefore, the large amount of non-combustible gas G3b obstructs the flow of the exhaust gas G1 entering the diffuser 12 from the internal space 103, suppressing the entry of the exhaust gas G1 into the diffuser 12, and suppressing the spontaneous ignition of the combustible gas G2 filled in the pipe 11.

[0048] In the above description, the ejection section 13B is provided with a plurality of upstream ejection holes 31a and a plurality of downstream ejection holes 31b, and the ejection amounts of the non-combustible gas G3a from the upstream ejection holes 31a and the non-combustible gas G3b from the downstream ejection holes 31b are different, but this is not limited to the configuration. For example, the types of ejection holes that have different ejection amounts are not limited to two, and may be three or more.

[0049] [Fourth embodiment] 6 is a cross-sectional view of a furnace showing a self-ignition prevention device according to a fourth embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed description thereof will be omitted.

[0050] 6, the self-ignition prevention device 10C includes a pipe 11, an expansion pipe 12, and a jetting part 13. The self-ignition prevention device 10C can adjust the flow rate of the non-flammable gas G3 jetted by the jetting part 13 according to the properties of the flammable gas G2. Here, the properties of the flammable gas G2 refer to, for example, the flow rate of the flammable gas G2 flowing through the pipe 11.

[0051] The pipe 11 is provided therein with a flow rate sensor 41 that measures the flow rate of the combustible gas G2. The control unit 42 adjusts the opening degree of the on-off valve 28 based on the flow rate of the combustible gas G2 detected by the flow rate sensor 41. The control unit 42 adjusts the opening degree of the on-off valve 28 to be larger as the flow rate of the combustible gas G2 flowing through the pipe 11 increases. In other words, the ejection unit 13 increases the flow rate of the non-combustible gas G3 ejected from the multiple ejection holes 31 as the flow rate of the combustible gas G2 flowing through the pipe 11 increases.

[0052] In the above description, the detector for detecting the properties of the combustible gas G2 is not limited to the flow sensor 41. As the detector for detecting the properties such as the flow rate and concentration of the combustible gas G2, a speed sensor for detecting the flow rate of the combustible gas G2, a concentration sensor for detecting the concentration of the combustible gas G2, a supply amount setting value or valve opening degree sensor in the supply device of the combustible gas G2, a sampling measurement device for the combustible gas G2, a laser instrumentation device, etc. may be applied. In addition, a map in which the injection amount of the non-combustible gas G3 relative to the supply amount setting value in the supply device of the combustible gas G2 is set may be prepared in advance, and the opening degree of the opening valve 28 may be adjusted based on the map.

[0053] [Fifth embodiment] 7 is a cross-sectional view of a furnace showing a self-ignition prevention device according to a fifth embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed description thereof will be omitted.

[0054] 7, the self-ignition prevention device 10D includes a pipe 11, an expansion pipe 12, and a jetting part 13. The self-ignition prevention device 10C can adjust the flow rate of the non-flammable gas G3 jetted by the jetting part 13 according to the properties of the exhaust gas G1. Here, the properties of the exhaust gas G1 include, for example, the temperature of the exhaust gas G1 entering the pipe 11.

[0055] The diffuser 12 is provided therein with a temperature sensor 43 that measures the temperature of the exhaust gas G1. The control unit 42 adjusts the opening of the on-off valve 28 based on the temperature of the exhaust gas G1 detected by the temperature sensor 43. The control unit 42 adjusts the opening of the on-off valve 28 to a larger degree as the temperature of the exhaust gas G1 that has entered the diffuser 12 becomes higher. In other words, the higher the temperature of the exhaust gas G1 that has entered the diffuser 12, the more the ejection unit 13 increases the flow rate of the nonflammable gas G3 ejected from the multiple ejection holes 31.

[0056] In the above description, the detector for detecting the properties of the exhaust gas G1 is not limited to the temperature sensor 43. As the detector for detecting the properties of the exhaust gas G1, a temperature sensor for detecting the temperature of the inner circumferential surface of the diffuser 12, a temperature sensor for detecting the temperature of the exhaust gas G1 rising in the internal space 103, a temperature sensor for detecting the temperature of the inner wall surface 102a of the furnace wall 102, a flow rate sensor (velocity sensor) for detecting the flow rate (flow velocity) of the exhaust gas G1 that has entered the diffuser 12, etc. may be applied. In addition, a map in which the injection amount of the non-combustible gas G3 relative to the temperature of the exhaust gas G1 that has entered the diffuser 12 is set may be prepared in advance, and the opening degree of the opening valve 28 may be adjusted based on the map. In addition, the opening degree of the opening valve 28 may be adjusted by executing PID control based on the detected properties of the exhaust gas G1.

[0057] [Effects of this embodiment] The spontaneous ignition prevention device according to the first embodiment includes a pipe 11 that can be filled with a combustible gas G2 and can communicate with an internal space (target area) 103 of a furnace 101, an expansion pipe 12 that is provided between the pipe 11 and a furnace wall 102 (internal space 103) and has an inner diameter larger than that of the pipe 11, and ejection parts 13, 13A, 13B that eject a non-combustible gas G3 from the outer periphery of the expansion pipe 12 toward the center.

[0058] According to the spontaneous ignition prevention device of the first aspect, when the piping 11 is filled with the combustible gas G2, the ejection parts 13A and 13B eject the non-combustible gas G3 from the outer periphery of the diffuser 12 toward the center, thereby forming an air curtain between the diffuser 12 and the internal space 103 of the furnace 101. The air curtain of the non-combustible gas G3 separates the inside of the diffuser 12 from the internal space 103, and therefore suppresses the intrusion of the exhaust gas G1 into the inside of the diffuser 12, and suppresses spontaneous ignition of the combustible gas G2 filled in the piping 11 by the exhaust gas G1.

[0059] Also, there is a risk that a part of the exhaust gas G1 will slip through the air curtain of the non-flammable gas G3 and enter the inside of the diffuser 12. This exhaust gas G1 will form a secondary flow F that swirls inside the diffuser 12 and will remain inside the diffuser 12. Therefore, the exhaust gas G1 will be less likely to flow to the pipe 11 side, and the spontaneous ignition of the combustible gas G2 filled in the pipe 11 can be suppressed.

[0060] Furthermore, even if a part of the exhaust gas G1 that has entered the diffuser 12 comes into contact with the combustible gas G2 filled in the piping 11, the combustible gas G2 is diluted by being mixed with the exhaust gas G1 whose temperature has been reduced, and the concentration of the combustible gas G2 decreases. Therefore, even if the combustible gas G2 diluted by being mixed with the exhaust gas G1 returns to the internal space 103 through the diffuser 12, spontaneous ignition of the combustible gas G2 can be suppressed.

[0061] As a result, large valves and the like are not required, and increases in parts costs and maintenance costs can be suppressed. In addition, the air curtain for non-flammable gas G3 that separates the diffuser 12 from the internal space 103 only requires providing the blowout part 13 on the diffuser 12, so there is no risk of malfunction even when placed in a high-temperature environment, and spontaneous ignition of the flammable gas G2 can be appropriately suppressed.

[0062] In the self-ignition prevention device according to the second aspect, the diffuser 12 expands in diameter continuously from the pipe 11 toward the internal space 103. As a result, the inner surface of the diffuser 12 expands in diameter without any steps, so that the exhaust gas G1 that has entered the diffuser 12 can be appropriately swirled and turned into a stagnant secondary flow F, and the self-ignition of the combustible gas G2 filled in the pipe 11 can be suppressed.

[0063] In the self-ignition prevention device according to the third aspect, the ejection parts 13, 13A, 13B eject the nonflammable gas G3 in an inclined direction inclined toward the internal space 103 with respect to the radial direction of the diffuser 12. As a result, an air curtain of the nonflammable gas G3 is formed so as to protrude toward the internal space 103, and the intrusion of the exhaust gas G1 from the internal space 103 into the diffuser 12 and the piping 11 can be effectively suppressed.

[0064] In the self-ignition prevention device according to the fourth aspect, the blowing part 13 is provided on the inner space 103 side of the diffuser 12. This allows the air curtain of the non-flammable gas G3 to appropriately suppress the intrusion of the exhaust gas G1 from the inner space 103 into the diffuser 12.

[0065] In the self-ignition prevention device according to the fifth aspect, the ejection part 13A is provided on the diffusor 12 on the side of the pipe 11. This allows the air curtain of the non-flammable gas G3 to appropriately suppress the intrusion of the exhaust gas G1 from the diffusor 12 into the pipe 11.

[0066] The self-ignition prevention device according to the sixth aspect has, as the ejection section 13B, an upstream ejection hole (upstream ejection section) 31a arranged upstream in the flow direction of the exhaust gas G1 flowing through the internal space 103, and a downstream ejection hole (downstream ejection section) 31b arranged downstream in the flow direction of the exhaust gas G1 in the internal space 103, and the amount of the non-combustible gas G3b ejected from the downstream ejection hole 31b is made greater than the amount of the non-combustible gas G3a ejected from the upstream ejection hole 31a. As a result, a large amount of the non-combustible gas G3b ejected from the downstream ejection hole 31b faces the flow of the exhaust gas G1 attempting to enter the internal space 103, and the intrusion of the exhaust gas G1 from the internal space 103 into the diffuser 12 and the piping 11 can be appropriately suppressed.

[0067] The self-ignition prevention device according to the seventh aspect sets the flow rate of the non-flammable gas G3 ejected from the ejection parts 13, 13A, 13B according to the properties of the combustible gas G2. As a result, the flow rate of the non-flammable gas G3 is set according to the flow rate, concentration, and other properties of the combustible gas G2, and therefore the intrusion of the exhaust gas G1 from the internal space 103 into the diffuser 12 and the piping 11 can be appropriately suppressed by the air curtain of the non-flammable gas G3.

[0068] The self-ignition prevention device according to the eighth aspect sets the flow rate of the nonflammable gas G3 ejected from the ejection parts 13, 13A, 13B according to the properties of the exhaust gas G1 in the internal space 103. In this way, the flow rate of the nonflammable gas G3 is set according to the temperature, flow rate, and the like, which are the properties of the exhaust gas G1, and therefore the intrusion of the exhaust gas G1 from the internal space 103 into the diffuser 12 and the piping 11 can be appropriately suppressed by the air curtain of the nonflammable gas G3.

[0069] In the above embodiment, the diffuser 12 is configured to be enlarged continuously and uniformly from one end connected to the piping 11 to the other end connected to the furnace 101, but the present invention is not limited to this configuration. For example, the diffuser 12 may be configured to be enlarged stepwise and discontinuously from one end to the other end.

[0070] In addition, in the above-described embodiments, the spontaneous ignition prevention devices 10, 10A, 10B, 10C, and 10D are applied to dust removal devices such as waste incinerators, integrated coal gasification combined cycle power generation facilities, and power generation boilers, but they can be applied to various plants that handle combustible gas G2. [Explanation of symbols]

[0071] 10,10A,10B,10C,10D Self-ignition prevention device 11 Piping 12 Expansion tube 13,13A,13B Spout part 21 Outer tube 22, 22a, 22b Gas flow section 23 Header 24, 24a, 24b Gas space section 25,25a,25b ports 26, 26a, 26b Gas supply lines 27 Gas supply source 28, 28a, 28b Opening and closing valves 31 Nozzle, 1st nozzle 32 2nd blowout hole 31a Upstream outlet 31b Downstream outlet 41 Flow Sensor 42 Control section 43 Temperature Sensor 101 Furnace 102 Furnace wall 103 Interior Space (Target Area) G1 Exhaust gas G2 Flammable gas G3, G3a, G3b, G4 Non-flammable gas F Secondary flow

Claims

1. A spontaneous ignition prevention device applied to a dust removal device that removes dust adhering to the inner wall of a furnace or the outer surface of a heat transfer tube, comprising: A pipe capable of being filled with a flammable gas and being connected to a target area; an expansion pipe provided between the pipe and the target area and having an inner diameter larger than an inner diameter of the pipe; a blowout section that blows out a non-flammable gas from an outer periphery of the diffuser toward a center portion of the diffuser to form an air curtain; Equipped with The air curtain separates the expansion tube from the target area. Self-ignition prevention device.

2. The expansion pipe continuously expands in diameter from the pipe toward the target area. The autoignition prevention device according to claim 1 .

3. The ejection section ejects the non-flammable gas in an inclined direction inclined toward the target area with respect to a radial direction of the diffuser. The self-ignition prevention device according to claim 1 or 2.

4. The ejection portion is provided on the target area side of the diffuser. The self-ignition prevention device according to any one of claims 1 to 3.

5. The jetting portion is provided on the piping side of the diffuser. The self-ignition prevention device according to any one of claims 1 to 4.

6. The ejection section has an upstream ejection section arranged on the upstream side of the flow direction of the gas flowing through the target area, and a downstream ejection section arranged on the downstream side of the flow direction of the gas in the target area, and an ejection amount of the non-combustible gas from the downstream ejection section is greater than an ejection amount of the non-combustible gas from the upstream ejection section. The self-ignition prevention device according to any one of claims 1 to 5.

7. The flow rate of the non-combustible gas ejected from the ejection portion is set according to the properties of the flammable gas. The self-ignition prevention device according to any one of claims 1 to 6.

8. The flow rate of the non-flammable gas ejected from the ejection portion is set according to the properties of the gas flowing through the target area. The self-ignition prevention device according to any one of claims 1 to 7.

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