Method for manufacturing a flame arrestor and flame arrestor

Abstract

To provide a flame arrestor having a flame suppression element that suppresses the deterioration of flashback prevention function. [Solution] The flame arrester 10 includes a flame suppression element 30 positioned in a pipe 20 through which a flammable fluid flows. The flame suppression element 30 is positioned in the pipe 29 and includes a metal block 34 which is a joint of multiple metal plates 35, and multiple flame suppression gaps 40 that penetrate a first surface 31 of the metal block 34 and a second surface 32 facing the opposite side of the first surface 31, so as to be in line with the flow direction of the flammable fluid. The multiple flame suppression gaps 40 are arranged in a matrix.

Description

[Technical Field]

[0001] The technologies disclosed herein relate to a method for manufacturing a flame arrester and to a flame arrester itself. [Background technology]

[0002] In the technical field related to flame arresters, flame arresters such as those disclosed in Patent Document 1 are known. In Patent Document 1, the cylindrical element (flame suppression element) of the flame arrester is constructed by stacking a number of ring-shaped plates with spacers in between so that slits are formed between each ring-shaped plate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-308230 [Overview of the project] [Problems that the invention aims to solve]

[0004] The flame suppression element of a flame arrestor has an opening called a flame suppression gap. The smaller the size of the flame suppression gap, the better the flashback prevention function.

[0005] The technology disclosed herein aims to provide a flame arrestor having a flame suppression element in which the reduction of flashback prevention function is suppressed. [Means for solving the problem]

[0006] This specification discloses a method for manufacturing a flame arrestor. The method for manufacturing a flame arrestor includes the steps of etching a metal plate to form a plurality of flame suppression gaps in the metal plate, and diffusion bonding the plurality of metal plates on which flame suppression gaps have been formed to form a flame suppression element of a flame arrestor. [Effects of the Invention]

[0007] The technology disclosed herein provides a flame arrestor having a flame suppression element in which the reduction of flashback prevention function is suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a plan view showing a hydrogen combustion boiler according to an embodiment. [Figure 2] Figure 2 is a side view showing a hydrogen combustion boiler according to an embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing a frame arrester according to an embodiment. [Figure 4] Figure 4 is a schematic plan view showing the flame suppression element according to the embodiment. [Figure 5] Figure 5 is a side view showing the flame suppression element according to the embodiment. [Figure 6] Figure 6 is a flowchart showing a method for manufacturing an anti-flammation element according to an embodiment. [Figure 7] Figure 7 is an enlarged view of a portion of the first surface of the flame suppression element according to the embodiment. [Figure 8] Figure 8 is an enlarged view of a portion of the first surface of a flame suppression element according to another embodiment. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings. In the embodiments, a three-dimensional Cartesian coordinate system will be set up, and the positional relationships of each part will be described with reference to the three-dimensional Cartesian coordinate system. The direction parallel to the X-axis in the horizontal plane will be defined as the X-axis direction. The direction parallel to the Y-axis perpendicular to the X-axis in the horizontal plane will be defined as the Y-axis direction. The direction parallel to the Z-axis perpendicular to both the X-axis and the Y-axis will be defined as the Z-axis direction. The +Z direction is upward, and the -Z direction is downward.

[0010] [Hydrogen combustion boiler] Figure 1 is a plan view showing a hydrogen-fired boiler 1 according to an embodiment. Figure 2 is a side view showing the hydrogen-fired boiler 1 according to the embodiment. The hydrogen-fired boiler 1 is a once-through boiler that uses hydrogen gas as a combustible fluid. The hydrogen-fired boiler 1 includes a boiler body 2, a blower 3, an air supply pipe 4, a water supply pipe 5, a fuel pipe 6, an exhaust stack 7, a feed water heater 8, a steam supply pipe 9, a flame arrester 10, a shut-off valve 11, a shut-off valve 12, and a gas governor 13.

[0011] The boiler body 2 includes a lower header, a plurality of water tubes, an upper header, a combustion chamber, and a burner 2A. The burner 2A is disposed on the upper part of the boiler body 2. The burner 2A injects hydrogen gas downward.

[0012] The blower 3 supplies combustion air to the boiler body 2. The air supply pipe 4 is connected to the boiler body 2. Combustion air is supplied from the blower 3 to the air supply pipe 4. The combustion air flows through the air supply pipe 4. The combustion air is supplied to the boiler body 2 via the air supply pipe 4.

[0013] The water supply pipe 5 is connected to the lower header of the boiler body 2. Water is supplied from a water supply source to the water supply pipe 5. The water flows through the water supply pipe 5. The water is supplied to the boiler body 2 via the water supply pipe 5.

[0014] The fuel pipe 6 is connected to the burner 2A. Hydrogen gas is supplied from a hydrogen gas supply source to the fuel pipe 6. The hydrogen gas flows through the fuel pipe 6. The hydrogen gas is supplied to the burner 2A via the fuel pipe 6.

[0015] The burner 2A generates a flame by combusting the hydrogen gas. The water supplied to the boiler body 2 is heated by the flame, and steam is generated. Combustion gas is generated by the combustion of hydrogen gas in the boiler body 2.

[0016] The exhaust stack 7 is connected to the boiler body 2. The combustion gas generated in the boiler body 2 flows through the exhaust stack 7. The combustion gas is discharged via the exhaust stack 7.

[0017] The feedwater heater 8 heats the water flowing through the feedwater pipe 5 by exchanging heat between the water supplied to the boiler 2 and the combustion gas flowing through the exhaust pipe 7. The water heated by the feedwater heater 8 is supplied to the boiler 2 via the feedwater pipe 5.

[0018] The steam supply pipe 9 is connected to the upper header of the boiler body 2. Steam generated in the boiler body 2 flows through the steam supply pipe 9. The steam is supplied to steam-using equipment (not shown) via the steam supply pipe 9.

[0019] The flame arrestor 10 is positioned in the fuel pipe 6. The flame arrestor 10 is a flashback prevention device that prevents flames generated in the burner 2A from propagating upstream in the fuel pipe 6.

[0020] Shut-off valves 11 and 12, and gas governor 13 are each located in the fuel line 6. Shut-off valves 11 and 12 open or close the flow path in the fuel line 6. When shut-off valves 11 and 12 are opened, hydrogen gas is supplied to burner 2A. When shut-off valves 11 and 12 are closed, the supply of hydrogen gas to burner 2A is stopped. Gas governor 13 is located between shut-off valves 11 and 12. Gas governor 13 regulates the pressure of the hydrogen gas flowing through the fuel line 6.

[0021] [Frame Arrester] Figure 3 is a schematic cross-sectional view showing a flame arrester 10 according to an embodiment. The flame arrester 10 comprises a pipe 20 through which hydrogen gas, which is a flammable fluid, flows, and a flame suppression element 30 connected to the pipe 20. The pipe 20 functions as a reducer and includes an upstream portion 20A that expands in diameter with respect to the flow direction and a downstream portion 20B that contracts in diameter with respect to the flow direction.

[0022] The pipe 20 is positioned in the middle of the fuel pipe 6. The pipe 20 may be considered as part of the fuel pipe 6. Flanges 20F are provided at both ends of the pipe 20. As shown in Figures 1 and 2, the pipe 20 is fixed to the fuel pipe 6 via the flanges 20F.

[0023] In the example shown in Figure 3, the central axis AX of pipe 20 is parallel to the Y-axis. Hydrogen gas flows inside pipe 20 in the Y-axis direction. The direction of hydrogen gas flow is in the Y-axis direction. Hydrogen gas flows inside pipe 20 in the +Y direction.

[0024] The flame suppression element 30 has a metal block 34 and a plurality of flame suppression gaps 40 provided in the metal block 34. The metal block 34 is connected to the pipe 20. Stainless steel is an example of the material used to form the metal block 34.

[0025] The metal block 34 has a cylindrical shape. The metal block 34 has a first surface 31, a second surface 32 facing the opposite side of the first surface 31, and an outer peripheral surface 33. The first surface 31 and the second surface 32 are substantially flat surfaces. The first surface 31 and the second surface 32 are substantially parallel. The first surface 31 and the second surface 32 are perpendicular to the central axis AX of the pipe 20. The first surface 31 faces upstream (-Y side) in the direction of hydrogen gas flow. The second surface 32 faces downstream (+Y side) in the direction of hydrogen gas flow. The periphery of the first surface 31 of the metal block 34 is welded to the open end of the upstream portion 20A of the pipe 20. The periphery of the second surface 32 of the metal block 34 is welded to the open end of the downstream portion 20B of the pipe 20. Instead of welding, it may be fastened by flanges.

[0026] The flame suppression gap 40 is an opening provided in the metal block 34. In this embodiment, the flame suppression gap 40 penetrates the first surface 31 and the second surface 32 of the metal block 34 along the direction of hydrogen gas flow. The flame suppression gap 40 is a straight through-hole parallel to the Y-axis that penetrates the first surface 31 and the second surface 32. Multiple flame suppression gaps 40 are provided at intervals from each other.

[0027] Hydrogen gas can flow through the flame suppression gap 40. The inlet 41 of the flame suppression gap 40 is provided on the first surface 31. The outlet 42 of the flame suppression gap 40 is provided on the second surface 32. Hydrogen gas flows into the flame suppression gap 40 from the inlet 41, flows through the flame suppression gap 40 in the +Y direction, and then flows out from the outlet 42. The hydrogen gas that flows out from the outlet 42 is supplied to the burner 2A.

[0028] Figure 4 is a schematic plan view of the flame suppression element 30 according to the embodiment. Figure 4 is a view of the flame suppression element 30 from the -Y side. As shown in Figure 4, the multiple flame suppression gaps 40 are arranged in a matrix in a plane perpendicular to the central axis AX. The spacing B between adjacent flame suppression gaps 40 is constant. In the plane perpendicular to the central axis AX, the shape of the flame suppression gaps 40 is square.

[0029] Figure 5 is a side view showing a flame suppression element 30 according to an embodiment. The metal block 34 is a joint of a plurality of metal plates 35. The metal plates 35 are disc-shaped. The surfaces of the metal plates 35 are substantially flat. The diameters W of the plurality of metal plates 35 are equal to each other. The thicknesses T of the plurality of metal plates 35 are equal to each other. The plurality of metal plates 35 are joined so as to be in close contact with each other. The surface of the first metal plate 35 facing the +Y side and the surface of the second metal plate 35 facing the -Y side, which is positioned next to the +Y side of the first metal plate 35, are in close contact.

[0030] [Method for manufacturing a flame arrestor] Figure 6 is a flowchart showing a method for manufacturing a flame suppression element 30 according to an embodiment. In this embodiment, the flame suppression element 30 comprises a first step S1 of etching a metal plate to form a plurality of flame suppression gaps 40 in the metal plate, and a second step S2 of diffusion bonding a plurality of metal plates 35 on which flame suppression gaps 40 are formed to form a flame suppression element 30 of the flame arrester 10.

[0031] In the first step S1, the metal plate is etched before the flame suppression gap 40 is formed. A metal plate with a diameter W and a thickness T is etched. In the first step S1, a photomask with a pattern for forming the flame suppression gap 40 is used. The flame suppression gap 40 is formed by photolithography. The first step S1 includes a resist coating step of coating the surface of the metal plate with photoresist, an exposure step of irradiating the metal plate coated with photoresist with exposure light through a photomask and a projection optical system, a developing step of removing the portion of the photoresist that has not been irradiated with exposure light, and an etching step of immersing the metal plate from which part of the photoresist has been removed in an etching solution to remove the portion of the metal plate that is not covered by the photoresist. By removing the portion of the metal plate that is not covered by the photoresist with the etching solution, a metal plate 35 with the flame suppression gap 40 formed is created.

[0032] In this embodiment, etching is performed such that the opening ratio, which indicates the proportion of the surface of the metal plate 35 occupied by the flame suppression gap 40, is between 5% and 75%.

[0033] After multiple metal plates 35 with flame-extinguishing gaps 40 are formed, a second step S2 is performed in which the multiple metal plates 35 are diffusion-bonded. Diffusion bonding is a method of bonding by bringing the base materials into close contact, applying pressure at a temperature below the melting point of the base materials to the extent that plastic deformation is minimized, and utilizing the diffusion of atoms that occurs between the bonding surfaces. In this embodiment, the base material is a metal plate 35. By bringing the surfaces of multiple metal plates 35 into close contact with each other and applying pressure at a temperature below the melting point of the metal plates 35, a flame-extinguishing element 30 is formed.

[0034] In this embodiment, diffusion bonding is performed such that the positions of the flame suppression gaps 40 of the multiple metal plates 35 coincide with each other. That is, as described with reference to Figure 3, diffusion bonding is performed with the flame suppression gaps 40 of the multiple metal plates 35 aligned so that flame suppression gaps 40, which are straight through-holes parallel to the Y-axis and penetrating the first surface 31 and the second surface 32, are formed. In this embodiment, for example, any number of metal plates 35, from 100 to 150, are diffusion-bonded to form a flame suppression element 30.

[0035] [Specifications of the anti-flame element]

[0036] Figure 7 is an enlarged view of a part of the first surface 31 of the flame suppression element 30 according to the embodiment. As shown in Figure 7, the shape of the flame suppression gap 40 is square. If the dimension of the flame suppression gap 40 is D, the thickness of the metal plate 35 is T, and the distance between adjacent flame suppression gaps 40 is B, the flame suppression element 30 may be formed to satisfy the first condition shown by the following equations (1A), (2A), and (3A). When the shape of the flame suppression gap 40 is square, the dimension D of the flame suppression gap 40 refers to the length of one side of the flame suppression gap 40.

[0037] D=0.3mm …(1A) T ≤ D …(2A) B≧0.5×T …(3A)

[0038] The dimension D of the flame suppression gap 40, which prevents flashback, changes depending on the type of flammable fluid. When hydrogen gas is used as the flammable fluid, it is recommended that the dimension D of the flame suppression gap 40 be 0.3 mm or less to prevent flashback. Equation (1A) specifies the recommended value for dimension D when the flammable fluid is hydrogen gas. Equations (2A) and (3A) specify the conditions for properly performing the etching process. As shown in equation (2A), when the etching process is properly performed, it is recommended that the plate thickness T be less than or equal to dimension D. As shown in equation (3A), when the etching process is properly performed, the recommended value of the gap B changes based on the plate thickness T.

[0039] Furthermore, if the dimension of the flame suppression gap 40 is D, the thickness of the metal plate 35 is T, and the pitch between adjacent flame suppression gaps 40 is P, the flame suppression element 30 may be formed to satisfy the second condition shown by the following equations (1B), (2B), and (3B).

[0040] D=0.3mm …(1B) T ≤ D …(2B) P ≥ D + 0.5 × T …(3B)

[0041] Similar to equation (1A), equation (1B) specifies the recommended value for dimension D when the flammable fluid is hydrogen gas. Similar to equation (2A), equation (2B) specifies the conditions for properly performing the etching process. As shown in equation (3B), when the etching process is performed properly, the recommended value for pitch P changes based on dimension D and plate thickness T.

[0042] The flame suppression element 30 may be formed to satisfy the third condition, which is that the opening ratio, which indicates the proportion of the first surface 31 occupied by the flame suppression gaps 40, is 25% or more and 75% or less. An opening ratio of less than 25% means that the spacing B is large and the number of flame suppression gaps 40 is small. If the number of flame suppression gaps 40 is small, it may be difficult to adequately supply hydrogen gas to the burner 2A. An opening ratio of more than 75% means that the spacing B is small. If the spacing B is too small, it may be difficult to properly carry out the etching process. Also, if the opening ratio is too high, the strength of the flame suppression element 30 may decrease. The flame suppression element 30 may be formed to satisfy the third condition, which is that the opening ratio is 25% or more and 75% or less, so that hydrogen gas can be adequately supplied to the burner 2A and the etching process can be properly carried out.

[0043] For example, if the dimension D of the flame suppression gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the spacing B is 0.05 mm, then the opening ratio per unit area of ​​the first surface 31 is approximately 73.5% (0.3 2 / (0.3+0.05) 2(=0.7346). When the dimension D of the flame suppression gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the spacing B is 0.1 mm, the opening ratio per unit area of ​​the first surface 31 is approximately 56.3% (0.3 2 / (0.3+0.1) 2 (=0.5625). When the dimension D of the flame suppression gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the spacing B is 0.2 mm, the opening ratio per unit area of ​​the first surface 31 is approximately 36.0% (0.3 2 / (0.3+0.2) 2 (=0.36).

[0044] [effect] As described above, in the embodiment, the method for manufacturing the flame arrester 10 includes a first step S1 of etching a metal plate to form a plurality of flame suppression gaps 40 in the metal plate, and a second step S2 of diffusion bonding the plurality of metal plates 35 on which the flame suppression gaps 40 are formed to form the flame suppression element 30 of the flame arrester 10.

[0045] According to the embodiment, a flame suppression element 30 having a small flame suppression gap 40 with dimension D is properly manufactured by etching a metal plate. The smaller the dimension D of the flame suppression gap 40, the better the flashback prevention function of the flame suppression element 30. Depending on the type of flammable fluid, the dimension D of the flame suppression gap 40 that can prevent flashback changes. When hydrogen gas is used as the flammable fluid, it is recommended that the dimension D of the flame suppression gap 40 be 0.3 mm or less in order to prevent flashback. According to the embodiment, a fine flame suppression gap 40 with dimension D of 0.3 mm or less is properly formed on the metal plate by etching. After the metal plate 35 having the fine flame suppression gap 40 is formed, a high-strength flame suppression element 30 is manufactured by diffusion bonding of multiple metal plates 35. According to the embodiment, a high-strength flame suppression element 30 is manufactured in which the deterioration of the flashback prevention function is suppressed.

[0046] The flame suppression element 30 is placed in the pipe 20 and comprises a metal block 34 which is a joint of multiple metal plates 35, and multiple flame suppression gaps 40 that penetrate a first surface 31 of the metal block 34 and a second surface 32 facing the opposite side of the first surface 31, so as to be in line with the flow direction of hydrogen gas, which is a flammable fluid. The multiple flame suppression gaps 40 are arranged in a matrix.

[0047] According to the embodiment, a high-strength flame suppression element 30 is provided in which the reduction in flashback prevention function is suppressed.

[0048] The opening ratio of the flame suppression gap 40 is between 25% and 75%. This provides a flame suppression element 30 with an optimal opening ratio that allows sufficient hydrogen gas to be supplied to the burner 2A, enables proper etching, and suppresses a decrease in flashback prevention function.

[0049] [Other embodiments] Figure 8 is an enlarged view of a part of the first surface 31 of the flame suppression element 30 according to another embodiment. As shown in Figure 8, the shape of the flame suppression gap 40 may be circular. When the shape of the flame suppression gap 40 is circular, the flame suppression element 30 may be formed to satisfy the first conditions shown by equations (1A), (2A), and (3A) above. When the shape of the flame suppression gap 40 is circular, the flame suppression element 30 may be formed to satisfy the second conditions shown by equations (1B), (2B), and (3B) above. When the shape of the flame suppression gap 40 is circular, the dimension D of the flame suppression gap 40 refers to the diameter of the flame suppression gap 40.

[0050] When the shape of the flame suppression gap 40 is circular, the flame suppression element 30 may be formed to satisfy the third condition, which is that the opening ratio, which indicates the proportion of the first surface 31 occupied by the flame suppression gap 40, is 25% or more and 75% or less. For example, if the dimension D of the flame suppression gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the spacing B is 0.05 mm, the opening ratio per unit area of ​​the first surface 31 is approximately 57.7% ([π × 0.3 2 / 4] / [0.3+0.05] 2= 0.5767). When the dimension D of the quenching gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the interval B is 0.1 mm, the opening ratio per unit area of the first surface 31 is approximately 44.2% ([π×0.3 2 / 4] / (0.3+0.1) 2 = 0.4415). When the dimension D of the quenching gap 40 is 0.3 mm, the plate thickness T is 0.1 mm, and the interval B is 0.2 mm, the opening ratio per unit area of the first surface 31 is approximately 28.3% ([π×0.3 2 / 4] / [0.3+0.2] 2 = 0.2826).

[0051] In the above embodiment, the shape of the quenching gap is circular or square. Alternatively, the shape of the quenching gap may be polygonal. As the polygon, for example, a hexagon or an octagon can be adopted.

[0052] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The flame arrester according to the present disclosure can be suitably mounted on a hydrogen-fueled boiler or the like that has a favorable impact on achieving carbon neutrality. Therefore, it can contribute to the realization of Goal 13 "Take urgent action to combat climate change and its impacts" of the SDGs (Sustainable Development Goals).

Description of Reference Numerals

[0053] 1... Hydrogen-fueled boiler, 2... Boiler body, 2A... Burner, 3... Blower, 4... Air supply pipe, 5... Water supply pipe, 6... Fuel pipe, 7... Exhaust stack, 8... Feed water heater, 9... Steam supply pipe, 10... Flame arrester, 11... Shut-off valve, 12... Shut-off valve, 13... Gas governor, 20... Pipe, 20F... Flange, 30... Quenching element, 31... First surface, 32... Second surface, 33... Outer peripheral surface, 34... Metal block, 35... Metal plate, 40... Quenching gap, 41... Inflow port, 42... Outflow port.

Claims

1. A process of etching a metal plate to form a plurality of flame-extinguishing gaps in the metal plate, The process includes a step of forming a flame suppression element for a flame arrestor by diffusion bonding a plurality of metal plates in which the flame suppression gaps are formed. A method for manufacturing a flame arrestor.

2. Multiple flame suppression gaps are arranged in a matrix. A method for manufacturing a flame arrestor according to claim 1.

3. The diffusion bonding is performed such that the positions of the flame-extinguishing gaps in each of the multiple metal plates coincide with each other. A method for manufacturing a flame arrestor according to claim 2.

4. The opening ratio, which indicates the proportion of the surface of the metal plate occupied by the flame-extinguishing gap, is 25% or more and 75% or less. A method for manufacturing a flame arrestor according to claim 3.

5. The shape of the anti-flammation gap is circular, square, or polygonal. A method for manufacturing a flame arrestor according to claim 1.

6. A flame arrestor comprising a flame suppression element placed in a pipe through which a flammable fluid flows, The aforementioned flame suppression element is A metal block, which is a joint of multiple metal plates, is placed in the aforementioned pipe, The device comprises a plurality of flame-extinguishing gaps that penetrate the first surface of the metal block and the second surface facing the opposite side of the first surface, so as to be in line with the flow direction of the flammable fluid, The aforementioned multiple anti-flammation gaps are arranged in a matrix. Frame arrestor.

7. The opening ratio, which indicates the proportion of the first surface occupied by the flame-extinguishing gap, is 25% or more and 75% or less. The frame arrestor according to claim 6.

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