AU2018238747A1

AU2018238747A1 - Burner and manufacturing method for same

Info

Publication number: AU2018238747A1
Application number: AU2018238747A
Authority: AU
Inventors: Masato Kawanari; Jun Koike; Katsushi Kosuge
Original assignee: Nippon Steel Engineering Co Ltd
Current assignee: Nippon Steel Engineering Co Ltd
Priority date: 2017-03-24
Filing date: 2018-03-15
Publication date: 2019-10-31
Anticipated expiration: 2038-03-15
Also published as: AU2018238747B2; CN110446890A; WO2018173922A1; JP6242522B1; JP2018162903A; CN110446890B

Abstract

This disclosure addresses the problem of supporting various fuel types with a simple configuration. A gasification burner 1 comprises a fuel pipe 10 configured so as to circulate fuel, a cylindrical cooling member 30 configured so as to circulate a cooling liquid therein, and a cylindrical nozzle tip 20 disposed between the fuel pipe 10 and the cooling member 30 near the distal ends of these. An oxidizing agent through-hole 21b that penetrates the nozzle tip 20 so as to extend along the axial direction of the nozzle tip 20 is provided in the cylinder wall of the nozzle tip 20. The nozzle tip 20 and the fuel pipe 10, and/or the nozzle tip 20 and the cooling member 30, are screwed together with a screw.

Description

Title of Invention

BURNER AND MANUFACTURING METHOD FOR SAME

Technical Field [0001] The present disclosure relates to a burner and a method of manufacturing a burner.

Background Art [0002] A gasification furnace for generating combustible gas or the like by gasifying a pulverized fuel in which a solid fuel such as coal is pulverized in a fine powder form. The gasification furnace includes a reaction furnace in which the pulverized fuel is subjected to gasification reaction, and a gasification burner disposed in the reaction furnace. An example configuration of the gasification burner is disclosed in Patent Literature 1, for example. The gasification burner includes a columnar nozzle tip provided with one fuel flow path through which the pulverized fuel flows, a plurality of oxidant flow paths through which oxidant flows, and a cooling water flow path through which cooling water flows. A distal end surface tip of the nozzle tip (hereinafter, simply referred to as a “distal end surface”) is exposed inside the reaction furnace.

[0003] The fuel flow path is located on a center line of the nozzle tip (hereinafter, simply referred to as a “center line”) to extend along the center line of the nozzle tip. A discharge port of the fuel flow path is open on the distal end surface. The plurality of oxidant flow paths extend along the center line, and are located to surround the fuel flow path. Each discharge port of the plurality of oxidant flow paths is open

FP17-0783-00 on the distal end surface, and is inclined toward the center line side with respect to the distal end surface. Therefore, the pulverized fuel discharged from the discharge port of the fuel flow path is mixed with the oxidant discharged from the discharge ports of the plurality of oxidant flow paths at a position located on the center line and separated as much as a predetermined distance from the distal end surface. Then, the pulverized fuel combusts inside the reaction furnace.

[0004] The cooling water flow path extends along the center line, and is located inside the nozzle tip to surround the plurality of oxidant flow paths. The cooling water flow path extends from a proximal end portion side of the gasification burner toward the distal end surface, turns back in the periphery of the distal end surface, and thereafter, extends again toward the proximal end portion side. That is, the cooling water flow path is not open on the distal end surface. The cooling water flow path has a function to cool the gasification burner (nozzle tip) by the internally circulating cooling water. In the gasification burner disclosed in Patent Literature 1, the fuel flow path, the plurality of oxidant flow paths, and the cooling water flow path are integrally formed in one nozzle tip.

Citation List

Patent Literature [0005] Patent Literature 1: Japanese Unexamined Patent Publication No. 2015-140436

Summary of Invention

Technical Problem [0006] The gasification furnace developed so far has been installed

FP17-0783-00 together in a facility such as a coal power plant. As a matter of course, the same fuel type (coal in a coal power plant) has been continuously used in the facility. Therefore, it is not assumed to change the fuel type to be used even in the gasification furnace. The reason is as follows. That is, if the fuel type is changed, a mixing state of the pulverized fuel and the oxidant is also changed. Accordingly, a flame length of flame generated in the gasification burner is also changed. Therefore, a large-scale remodeling of the gasification furnace is needed to provide the reaction furnace with a size suitable for the changed flame length.

[0007] In order to reduce the impact of the environment, biomass co-firing power generation technology, which uses a mixed fuel of coal and biomass fuel (for example, wood pellets or wood chips), has attracted attention in recent years. In order to achieve even greater power generation efficiency, research and development of the technology continues on a daily basis. That is, the mixing ratio of the coal and the biomass fuel may be changed in the future, depending on research and development trends. However, a change in the mixing ratio corresponds to a change in the fuel type, which leads to a change in the flame length in the gasification burner. Therefore, it is difficult to perform the large-scale remodeling of the gasification furnace in response to the continuously researched and developed technology. Therefore, demand for a gasification burner capable of handling various fuel types without remodeling the gasification furnace is predicted in the future.

[0008] In view of the above, the present disclosure hereinafter describes

FP17-0783-00 a burner capable of handling various fuel types by means of a simple configuration, and a method of manufacturing the burner.

Solution to Problem [0009] (1) A burner according to an aspect of the present disclosure comprises a fuel pipe through which a fuel flows, a cylindrical cooling member through which a coolant internally circulates, and a cylindrical nozzle tip into which a distal end periphery of the fuel pipe is inserted, and which is inserted into a distal end periphery of the cooling member. A cylinder wall of the nozzle tip is internally provided with an oxidant flow path penetrating the nozzle tip to extend along an axial direction of the nozzle tip. At least one of a portion between the nozzle tip and the fuel pipe and a portion between the nozzle tip and the cooling member is fastened by screwing.

[0010] In the burner according to the aspect of the present disclosure, at least one of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member is fastened by screwing. Therefore, the nozzle tip is very easily attached to and detached from the fuel pipe and the cooling member. Thus, by preparing a plurality of types of the nozzle tips having mutually different flow path directions, it is possible to cope with a change in fuel types by simply replacing the nozzle tips without remodeling a gasification furnace. As a result, it is possible to handle various fuel types by means of a simple configuration.

[0011] (2) In the burner according to section (1) described above, one of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member may be fastened by

FP17-0783-00 screwing, and the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member may be fitted.

[0012] (3) In the burner according to section (2) described above, the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member may be clearance-fitted so that a tolerance zone of a hole is any one of D to H and a tolerance zone of a shaft is any one of d to h, the tolerance zones being defined in JIS B 0401-1: 2016 (ISO286-1: 2010). The burner is used inside a high-temperature reaction furnace. Accordingly, the nozzle tip and the fuel pipe thermally expand when in use. Therefore, if the two members are clearance-fitted under the above-described condition, a clearance is present between the two members when the cooling member is manufactured. Accordingly, both of these can be easily assembled to each other. On the other hand, if the two members are clearance-fitted under the above-described condition, the clearance decreases due to an action of thermal expansion when the burner is used. Accordingly, oxidant can be prevented from flowing out of the clearance.

[0013] (4) In the burner according to section (3) described above, a length of the clearance-fit on the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member may be 1 cm or longer. If the length of the clearance-fit is 1 cm or longer, even if the oxidant flows out of the clearance between the two clearance-fitted members instead of the flow path of the nozzle tip, an outflow volume thereof tends to be negligible.

FP17-0783-00

Therefore, a flame length of flame generated in the burner is less likely to be affected.

[0014] (5) In the burner according to any one of sections (1) to (4) described above, a distal end portion of the cooling member may be formed of a nickel alloy in which a content of Ni with respect to a total mass of the distal end portion is 40% by mass or more. Incidentally, combustion of the fuel inside the reaction furnace may generate acid gas (for example, hydrogen sulfide or hydrogen chloride) inside the reaction furnace in some cases. When the reaction furnace starts an operation and stops the operation, if a temperature inside the reaction furnace is lowered, the acidic gas becomes an acidic liquid, and adheres to the distal end periphery of the burner, thereby corroding the distal end periphery. This phenomenon is called “dew point corrosion”. In addition, when the cooling member is used, the outer surface is heated to a high temperature by heat transferred from the reaction furnace, and the cooling member is internally cooled by the coolant. Accordingly, stress corrosion cracking is likely to occur. However, in the burner according to section (5), the distal end portion of the cooling member is formed of the above-described material having high corrosion resistance. Accordingly, the cooling member is less likely to suffer dew point corrosion, and stress corrosion cracking of the cooling member can be prevented.

[0015] (6) In the burner according to any one of sections (1) to (5) described above, a distal end portion of the cooling member may be connected to a proximal end portion by welding, and a portion closer to the distal end portion in the proximal end portion may be formed of

FP17-0783-00 stainless steel subjected to solution treatment. In this case, the corrosion resistance of the stainless steel that has been degraded by welding is recovered by the solution treatment. This enables stress corrosion cracking of the cooling member to be further prevented. [0016] (7) In the burner according to any one of sections (1) to (4) described above, a distal end portion of the cooling member may be connected to a proximal end portion by welding, and a covering layer may be located on a surface of the distal end portion to cover a region including a welding portion between the distal end portion and the proximal end portion. In this case, the region whose corrosion resistance has been degraded by the welding is covered with the covering layer. This enables stress corrosion cracking of the cooling member to be further prevented.

[0017] (8) In the burner according to section (7) described above, the covering layer may be formed of a nickel alloy in which a content of Ni with respect to a total mass of the distal end portion is 40% by mass or more. In this case, the covering layer is formed of the above-described material having high corrosion resistance. Accordingly, the covering layer is less likely to suffer dew point corrosion. This enables stress corrosion cracking of the cooling member to be further prevented.

[0018] (9) In the burner according to section 8 described above, the distal end portion may be formed of copper, and the proximal end portion may be formed of stainless steel. In this case, the copper, which has high thermal conductivity but low corrosion resistance, is covered with the covering layer. This enables stress corrosion cracking of the distal end portion to be prevented by the covering layer

FP17-0783-00 while heat exchange is promoted in the distal end portion which is most likely to receive the heat transferred from the reaction furnace. In addition, copper is cheaper than stainless steel. Accordingly, the cost of the cooling member can be reduced.

[0019] (10) In the burner according to any one of sections (1) to (9) described above, the cooling member may include a cylindrical outer peripheral wall, a cylindrical inner peripheral wall located inside the outer peripheral wall, a distal end wall connecting distal ends of the outer peripheral wall and the inner peripheral wall to each other, and a cylindrical internal wall located between the outer peripheral wall and the inner peripheral wall to be separated from both of these. Spacers may be disposed between the internal wall, and the distal end wall, the outer peripheral wall or the inner peripheral wall. In this case, the spacer secures a space between the internal wall, and the distal end wall, the outer peripheral wall or the inner peripheral wall. This enables the coolant to flow smoothly inside the space.

[0020] (11) In the burner according to any one of sections (1) to (10) described above, a distal end of the fuel pipe may be exposed on a distal end surface of the nozzle tip. In this case, even if the fuel pipe, when in use, thermally expands due to the heat received from the reaction furnace and extends to the nozzle tip, the extension is not regulated by the nozzle tip. Therefore unnecessary stress can be prevented from being generated between the nozzle tip and the fuel pipe. In addition, in this case, the fuel flows through the fuel pipe without contacting the nozzle tip, and is discharged into the reaction furnace, unlike a case where the fuel pipe is attached to the nozzle tip in a state where the

FP 17-0783-00 distal end of the fuel pipe remains inside the nozzle tip. This makes it possible to minimize the possibility that the nozzle tip may be worn by contacting with the fuel.

[0021] (12) In the burner according to any one of sections 1 to 11 described above, a coefficient of thermal expansion of the fuel pipe may be higher than a coefficient of thermal expansion of the nozzle tip. In this case, if the fuel pipe and the nozzle tip, when in use, thermally expand due to the heat received from the reaction furnace, the fuel pipe is firmly fastened to the nozzle tip since the fuel pipe has the higher coefficient of thermal expansion. This makes it possible to prevent the oxidant from flowing out of both the clearances.

[0022] (13) A method of manufacturing a burner according to another aspect of the present disclosure includes a first step of preparing a fuel pipe through which a fuel flows, a second step of preparing a cylindrical cooling member through which a coolant internally circulates, a third step of preparing a cylindrical nozzle tip in which an oxidant flow path penetrating to extend along an axial direction is disposed inside a cylindrical wall, and a fourth step of inserting a distal end of the fuel pipe into the nozzle tip and inserting the nozzle tip into a distal end periphery of the cooling member. The fourth step includes screwing on at least one of a portion between the nozzle tip and the fuel pipe and a portion between the nozzle tip and the cooling member. The method of manufacturing the burner according to another aspect of the present disclosure has the same advantageous effects as those of the burner according to section (1) described above.

[0023] (14) In the method according to section (13) described above,

FP17-0783-00 the cooling member may be obtained through a first sub-step of preparing a distal end portion of the cooling member configured so that one end of a double pipe is closed by a distal end wall and an inner pipe is longer than an outer pipe, an inner cylindrical portion corresponding to an inner peripheral wall of the cooling member and formed of stainless steel, and an outer cylindrical portion corresponding to an outer peripheral wall of the cooling member and formed of stainless steel, a second sub-step of welding the other end of the inner pipe and one end of the inner cylindrical portion to each other, after the first sub-step, a third sub-step of forming an integrated component by welding the other end of the outer pipe and one end of the outer cylindrical portion to each other, after the second sub-step, and a fourth sub-step of (A) performing a solution treatment on stainless steel forming the inner cylindrical portion and the outer cylindrical portion by heating the integrated component, or (B) forming a covering layer in a distal end periphery of the integrated component to cover a region including a welded location between the distal end portion and the outer cylindrical portion, after the third sub-step. In this case, the same advantageous effects as those of the burner according to section (6) or (7) described above can be achieved.

Effects of Invention [0024] According to a burner and a method of manufacturing a burner in the present disclosure, it is possible to handle various fuel types by means of a simple configuration.

Brief Description of Drawings [0025] FIG. 1 is a schematic view illustrating an example of a

FP17-0783-00 gasification furnace according to the present embodiment.

FIG. 2 is a sectional view illustrating an example of a gasification burner.

FIG. 3 is an enlarged sectional view illustrating a distal end portion of the gasification burner.

FIG. 4 is a sectional view taken along line IV-IV illustrated in FIG. 3.

FIG. 5 is a view for describing a manufacturing step of the gasification burner.

FIG. 6 is a view for describing a manufacturing step of the gasification burner.

FIG. 7 is a sectional view illustrating another example of the gasification burner.

FIG. 8 is a sectional view illustrating another example of the gasification burner.

FIG. 9 is a sectional view illustrating another example of the gasification burner.

FIG. 10 is a sectional view illustrating another example of the gasification burner.

Description of Embodiments [0026] An embodiment according to the present disclosure described below is an example for describing the present invention. Therefore, the present invention should not be limited to the following contents. In the following description, the same reference numerals will be used for the same elements or elements having the same functions, and repeated description thereof will be omitted.

FP17-0783-00 [0027] [Coal Gasifier]

First, as an example of a facility using a gasification burner 1 (burner) according to the present embodiment, a coal gasifier 100 will be described with reference to FIG. 1. The coal gasifier 100 includes a furnace bottom section 101, a partial oxidation section 102 (reaction furnace), and a pyrolysis section 103 (reaction furnace). The furnace bottom section 101, the partial oxidation section 102, and the pyrolysis section 103 are all cylindrical and are connected in this order from the bottom to the top.

[0028] The furnace bottom section 101 has a function to receive a molten slug S generated in the partial oxidation section 102. For example, water is stored in the furnace bottom section 101. The slug S fallen from the partial oxidation section 102 is cooled in the furnace bottom section 101, and thereafter, is discharged outward of a bottom wall of the furnace bottom section 101.

[0029] The partial oxidation section 102 has a function to partially combust the pulverized coal serving as the pulverized fuel in an atmosphere of high temperature (for example, approximately l,550°C to l,650°C). A peripheral wall of the partial oxidation section 102 is provided with at least one gasification burner 1 for supplying the pulverized coal and the oxidant into the partial oxidation section 102.

[0030] The pulverized coal partially combusted in the partial oxidation section 102 is changed to combustible high-temperature gas G1 (for example, carbon monoxide gas, carbon dioxide gas, hydrogen gas, or steam gas), and is supplied to the pyrolysis section 103 located above. Ash contained in the pulverized coal melts during gasification, and falls

FP17-0783-00 to the furnace bottom section 101 as the slug S.

[0031] The pyrolysis section 103 has a function to perform pyrolysis on the pulverized coal by using the high-temperature gas G1 supplied from the partial oxidation section 102, and to obtain pyrolysis gas G2 (for example, carbon monoxide gas, hydrogen gas, or methane gas). A peripheral wall of the pyrolysis section 103 is provided with at least one supply nozzle 104 for supplying the pulverized coal to the pyrolysis section 103. The pyrolysis gas G2 generated in the pyrolysis section 103 is discharged outward of the furnace from a furnace top portion of the coal gasifier 100.

[0032] [Details of Gasification Burner]

Subsequently, details of the gasification burner 1 will be described with reference to FIGS. 2 to 4. As illustrated in FIG. 2, the gasification burner 1 is attached to the peripheral wall of the partial oxidation section 102 via an insulation material 105. As illustrated in FIGS. 2 to 4, the gasification burner 1 includes a fuel pipe 10, a nozzle tip 20, and a cooling member 30.

[0033] The fuel pipe 10 functions as a flow path of a pulverized coal serving as a fuel. The fuel pipe 10 is a straight pipe extending in one direction in the present embodiment. Specifically, the pulverized coal is transported inside the fuel pipe 10 by using inert gas (for example, nitrogen gas) as a carrier gas. The fuel pipe 10 may be made of a heat-resistant material (for example, stainless steel). The stainless steel may be SUS310S, for example.

[0034] As illustrated in FIGS. 2 to 4, the nozzle tip 20 is located between the fuel pipe 10 and the cooling member 30 and in the distal

FP17-0783-00 end periphery thereof. The nozzle tip 20 may be made of a heat-resistant material (for example, stainless steel). The stainless steel may be SUS310S, for example.

[0035] As illustrated in FIGS. 3 and 4, the nozzle tip 20 includes a main body portion 21 having a disk shape, and an extension portion 22 disposed integrally with the main body portion 21. The main body portion 21 is provided with one through-hole 21a and a plurality of through-holes 21b (flow paths). The through-hole 21a extends on a central axis of the main body portion 21, and penetrates the main body portion 21 in a thickness direction. Therefore, the main body portion 21 has a cylindrical shape. A male screw Ms (screw) is disposed on an outer peripheral surface of the main body portion 21.

[0036] The plurality of through-holes 21b (in the present embodiment, eight through-holes 21b as illustrated in FIG. 4) are aligned with each other in a circular shape to surround the through-hole 21a, when viewed in a direction of the central axis of the main body portion 21. Therefore, the plurality of through-holes 21b are disposed inside the peripheral wall (cylinder wall) of the cylindrical main body portion 21. Each through-hole 21b penetrates along a central axis direction of the main body portion 21. Each through-hole 21b is inclined to be closer to the central axis of the main body portion 21 from a rear end surface SI side toward a distal end surface S2 of the main body portion 21. An inclination angle of the through-hole 21b with respect to the central axis can be set to various sizes, depending on a fuel type supplied from the fuel pipe 10, a size of the partial oxidation section 102, or the like. The inclination angle may be 10° to 50°, for example. Each

FP17-0783-00 through-hole 21b functions as a flow path of the oxidant (for example, a mixed gas of oxygen and steam).

[0037] The extension portion 22 has a cylindrical shape, and extends from the rear end surface SI along the central axis of the main body portion 21. A cylinder hole 22a of the extension portion 22 communicates with the through-hole 21a of the main body portion 21. The distal end portion of the fuel pipe 10 is inserted into the through-hole 21a and the cylinder hole 22a. In the present embodiment, as illustrated in FIGS. 2 to 4, the distal end of the fuel pipe 10 is located substantially flush with the distal end surface S2 of the nozzle tip 20, and is exposed from the distal end surface S2.

[0038] In the present embodiment, the distal end periphery of the fuel pipe 10 is inserted into the through-hole 21a of the nozzle tip 20. Specifically, the nozzle tip 20 and the fuel pipe 10 are fitted to each other. The nozzle tip 20 and the fuel pipe 10 may be fitted to each other by means of interference-fit, may be fitted to each other by means of clearance-fit, or may be fitted to each other by means of intermediate-fit. In a case of the clearance-fit or the intermediate-fit, a tolerance zone of a hole (inner peripheral surface of the through-hole 21a and the cylinder hole 22a) defined in JIS B 0401-1: 2016 (ISO286-1: 2010) may be any one of D to H, and a tolerance zone of a shaft (outer peripheral surface of the fuel pipe 10) defined in JIS B 0401-1: 2016 (ISO286-1: 2010) may be any one of d to h.

[0039] More specifically, in a case where a combination between a tolerance zone class X of the hole (inner peripheral surface of the through-hole 21a and the cylinder hole 22a) and a tolerance zone class y

FP17-0783-00 of the shaft (outer peripheral surface of the fuel pipe 10) is expressed as “X/y”', the combination may be so-called “light-fit” (one type of the clearance-fit) which is “H8/d9”, “H9/d9”, “H7/e7”, “H8/e8”, or “H9/e9”. The combination may be so-called “normal-fit” (one type of clearance-fit) which is “H6/f6”, “H7/f7”, “H8/f7”, or “H8/f8”. The combination may be so-called “precise-fit” (one type of clearance-fit) which is “H6/g5” or “H7/g6”. The combination may be so-called “slide-fit” (one type of intermediate-fit) which is “H6/h5”, “H7/h6”, “H8/h7”, “H8/h8”, or “H9/h9”. The combination may be so-called “press-fit” (one type of intermediate-fit) which is “H6/h5” or “H6/h6”. [0040] In a case of the clearance-fit, a length of the clearance-fit (fitting length between the holes 21a, 22a and the fuel pipe 10) may be 1 cm or longer, 3 cm or longer, 3.5 cm or longer, or 5 cm or longer. If the length of the clearance-fit is 1 cm or longer, when a theoretical value of a leak amount is calculated using a calculation model of the gasification burner 1 in which the fuel pipe 10, the nozzle tip 20 and the cooling member 30 are concentrically located, a flow rate of the oxidant which can leak from the clearance between the nozzle tip 20 and the fuel pipe 10 is 1% or smaller than the flow rate of the oxidant discharged from the through-hole 21b. Therefore, a flame length of flame generated in the gasification burner 1 is less likely to be affected.

[0041] The cooling member 30 has a cylindrical shape as a whole, and is configured so that the coolant circulates inside thereof (inside the cylinder wall). The gasification burner 1 is used inside the partial oxidation section 102 having a high temperature. Accordingly, the coolant has a function to cool the cooling member 30 through heat

FP17-0783-00 exchange and to prevent the cooling member 30 from being damaged.

As illustrated in FIGS. 3 and 4, the cooling member 30 includes a distal end portion 31, intermediate portions 32 and 33, proximal end portions and 35, and an internal wall 36.

[0042] The distal end portion 31 may be made of a heat resistant material. Incidentally, the combustion of the fuel inside the partial oxidation section 102 may generate acid gas (for example, hydrogen sulfide or hydrogen chloride) inside the partial oxidation section 102 in some cases. When the coal gasifier 100 starts an operation and stops the operation, if a temperature inside the partial oxidation section 102 is lowered, the acidic gas becomes an acidic liquid, and adheres to the distal end periphery of the gasification burner 1, thereby corroding the distal end periphery (dew point corrosion). In addition, when the cooling member 30 is used, the outer surface is heated to a high temperature by the heat transferred from the partial oxidation section 102 and the cooling member 30 is internally cooled by the coolant. Accordingly, the stress corrosion cracking is likely to occur. Therefore, for example, the distal end portion 31 may be made of a nickel alloy in which a content of Ni with respect to a total mass is 40% by mass or more. The nickel alloy has high corrosion resistance. Accordingly, the cooling member 30 (distal end portion 31) is less likely to suffer dew point corrosion, and stress corrosion cracking of the cooling member 30 (distal end portion 31) can be prevented. For example, the nickel alloy includes Inconel 718 and Alloy 718.

[0043] As illustrated in FIG. 3, the distal end portion 31 is configured to include a distal end wall 31a, an inner pipe 31b, and an outer pipe 31c.

FP17-0783-00

The distal end wall 31a is a flat plate having an annular shape. The distal end wall 31a is located substantially flush with the distal end surface S2 of the nozzle tip 20. Both the inner pipe 31b and the outer pipe 31c have a cylindrical shape. One end of the inner pipe 31b is integrally disposed in an inner peripheral edge of the distal end wall 31a. One end of the outer pipe 31c is integrally disposed in an outer peripheral edge of the distal end wall 31a. In other words, the inner pipe 31b and the outer pipe 31c configure a double pipe, and the inner pipe 31b is located inside the outer pipe 31c. The distal end wall 31a closes one end of the inner pipe 31b and one end of the outer pipe 31c. [0044] Both the inner pipe 31b and the outer pipe 31c extend from the distal end wall 31a toward the same side (base end side of the cooling member 30). In the present embodiment, the length of the inner pipe 31b is longer than the length of the outer pipe 31c. That is, the other end of the inner pipe 31b is located on the proximal end side of the cooling member 30 from the other end of the outer pipe 31c. Therefore, the other end of the inner pipe 31b is not covered with the outer pipe 31c when viewed from the outside in the radial direction of the inner pipe 31b and the outer pipe 31c.

[0045] A female screw Fs (screw) is disposed in the distal end portion on the inner peripheral surface of the inner pipe 31b. The female screw Fs can be screwed to the male screw Ms disposed on the outer peripheral surface of the nozzle tip 20. In the present embodiment, the male screw Ms of the nozzle tip 20 is screwed to the female screw Fs of the inner pipe 31b. In this manner, the nozzle tip 20 is inserted into the distal end periphery of the cooling member 30.

FP17-0783-00 [0046] Both the intermediate portions 32 and 33 have a cylindrical shape as illustrated in FIGS. 2 to 4. As illustrated in FIG. 3, one end of the intermediate portion 32 (inner cylindrical portion) is joined to the other end of the inner pipe 3 lb via a welding portion W1. One end of the intermediate portion 33 (outer cylindrical portion) is joined to the other end of the outer pipe 31c via a welding portion W2. In other words, the intermediate portions 32 and 33 configure a double pipe, and the intermediate portion 32 is located inside the intermediate portion 33. The intermediate portions 32 and 33 function as portions of the proximal end portion of the cooling member 30.

[0047] In the present embodiment, the intermediate portions 32 and 33 have substantially the same length. Therefore, the other end of the intermediate portion 32 connected to the inner pipe 3 lb is located on the proximal end side of the cooling member 30 from the other end of the intermediate portion 33 connected to the outer pipe 31c. That is, the other end of the intermediate portion 32 is not covered with the intermediate portion 33 when viewed from the outside in the radial direction of the intermediate portions 32 and 33.

[0048] The intermediate portions 32 and 33 may be made of a heat-resistant material (for example, stainless steel). The stainless steel used for the intermediate portion 32 may be SUS310S, for example. The stainless steel used for the intermediate portion 33 may be SUS310S, for example. In a case where the intermediate portions 32 and 33 are made of the stainless steel, the stainless steel may be subjected to solution treatment.

[0049] Both the proximal end portions 34 and 35 have a cylindrical

FP17-0783-00 shape as illustrated in FIGS. 2 to 4. The proximal end portion 34 and may be made of a heat-resistant material (for example, stainless steel). The stainless steel used for the proximal end portion 34 may be SUS304, for example. The stainless steel used for the proximal end portion 35 may be SUS310S, for example. One end of the proximal end portion 34 is joined to the other end of the intermediate portion 32 via a welding portion W3. One end of the proximal end portion 35 is joined to the other end of the intermediate portion 33 via the welding portion W2. In other words, the proximal end portions 34 and 35 configure a double pipe, and the proximal end portion 34 is located inside the proximal end portion 35.

[0050] The inner pipe 31b, the intermediate portion 32, and the proximal end portion 34 which are joined by welding configure an inner peripheral wall of the cooling member 30 as a whole. The outer pipe 31c, the intermediate portion 33, and the proximal end portion 35 which are joined by welding configure an outer peripheral wall of the cooling member 30 as a whole.

[0051] The internal wall 36 has a cylindrical shape as illustrated in FIGS. 2 to 4. The internal wall 36 is located between the inner peripheral wall (the inner pipe 31b, the intermediate portion 32, and the proximal end portion 34) of the cooling member 30 and the outer peripheral wall (the outer pipe 31c, the intermediate portion 33, and the proximal end portion 35) of the cooling member 30. The internal wall is provided with a plurality of spacers 36a and a plurality of spacers 36b.

[0052] As illustrated in FIGS. 3 and 4, the plurality of spacers 36a have

FP17-0783-00 a columnar shape, and are disposed on the distal end surface of the internal wall 36. In the present embodiment, three spacers 36a are aligned with each other at a substantially equal interval in the circumferential direction of the internal wall 36. The plurality of spacers 36a protrude outward from the distal end surface of the internal wall 36 in an extending direction of the internal wall 36. Therefore, the spacers 36a are located between the distal end wall 31a and the internal wall 36. In this manner, the internal wall 36 maintains a state of being separated from the distal end wall 31a of the cooling member 30.

[0053] As illustrated in FIGS. 3 and 4, the plurality of spacers 36b have a quadrangular prism shape, and are disposed on the outer peripheral surface of the internal wall 36 in the distal end periphery of the internal wall 36. In the present embodiment, three spacers 36b are aligned with each other at a substantially equal interval in the circumferential direction of the internal wall 36. The plurality of spacers 36b protrude outward from the outer peripheral surface of the internal wall 36 in the radial direction of the internal wall 36. Therefore, the plurality of spacers 36b are located between the outer peripheral wall (proximal end portion 35) and the internal wall 36 of the cooling member 30. In this manner, the internal wall 36 maintains a state of being separated from the outer peripheral wall (proximal end portion 35) of the cooling member 30. In addition, by providing the spacers 36b on the outer peripheral surface of the internal wall 36, rigidity is improved, and the distal end periphery of the internal wall 36 is less likely to deform. Accordingly, the internal wall 36 maintains a state of being separated

FP17-0783-00 from the inner peripheral wall (proximal end portion 34) of the cooling member 30.

[0054] As illustrated in FIG. 2, the other end of the proximal end portion 34 is connected to the outer peripheral surface of the fuel pipe 10 by welding via the proximal end wall 34a. The proximal end wall 34a is an annular flat plate, and the fuel pipe 10 is inserted into the through-hole of the proximal end wall 34a. Therefore, a space VI surrounded by the fuel pipe 10, the outer peripheral wall of the cooling member 30, the proximal end wall 34a, and the nozzle tip 20 is formed. A pipe 34b communicating with the space VI is disposed in the vicinity of the other end of the proximal end portion 34. The pipe 34b is connected to a supply source (not illustrated) of the oxidant. The oxidant is supplied into the space VI through the pipe 34b, flows toward the nozzle tip 20 inside the space VI, and thereafter, is discharged from the through-hole 21b.

[0055] As illustrated in FIG. 2, the other end of the internal wall 36 is connected to the outer peripheral surface of the proximal end portion 34 by welding. That is, the other end of the internal wall 36 is located closer to the nozzle tip 20 than the other end of the proximal end portion 34. Therefore, a space V2 surrounded by the inner peripheral wall of the cooling member 30, the internal wall 36, and the distal end wall 31a is formed. A pipe 36c communicating with the space V2 is disposed in the vicinity of the other end of the internal wall 36. The pipe 36c is connected to a heat exchanger (not illustrated).

[0056] As illustrated in FIG. 2, the other end of the proximal end portion 35 is connected to the outer peripheral surface of the internal

FP17-0783-00 wall 36 by welding. That is, the other end of the proximal end portion 35 is located closer to the nozzle tip 20 than the other end of the internal wall 36. Therefore, a space V3 surrounded by the outer peripheral wall of the cooling member 30, the internal wall 36, and the distal end wall 31a is formed. A pipe 36d communicating with the space V3 is disposed in the vicinity of the other end of the proximal end portion 35. The pipe 36d is connected to a heat exchanger (not illustrated).

[0057] The coolant supplied into the space V2 from the pipe 36c flows inside the space V2 toward the nozzle tip 20. Thereafter, the coolant turns back between the distal end wall 31a and the distal end of the internal wall 36, and flows inside the space V3 toward the pipe 36d. The coolant is discharged outward of the cooling member 30 from the pipe 36d. Thereafter, the coolant is cooled by the heat exchanger, and is introduced again into the pipe 36c from the heat exchanger.

[0058] [Method of Manufacturing Gasification Burner]

Subsequently, a method of manufacturing the gasification burner 1 will be described with reference to FIGS. 5 and 6. First, the cooling member 30 is prepared. Specifically, as illustrated in FIG. 5(a), the other end of the inner pipe 31b of the distal end portion 31 and one end of the intermediate portion 32 are caused to face each other. In this state, the other end of the inner pipe 3 lb and one end of the intermediate portion 32 are welded to each other. In this manner, as illustrated in FIG. 5(b), the inner pipe 31b and the intermediate portion 32 are joined to each other by the welding portion Wl. In this case, the other end of the inner pipe 31b is located on the proximal end side of the cooling member 30 from the other end of the outer pipe 31c. Accordingly, a

FP17-0783-00 welding torch is less likely to be hindered by the outer pipe 31c when the welding torch is directed between the other end of the inner pipe 31b and one end of the intermediate portion 32.

[0059] Next, as illustrated in FIG. 5(b), the other end of the outer pipe 31c of the distal end portion 31 and one end of the intermediate portion 33 are caused to face each other. In this state, the other end of the outer pipe 31c and one end of the intermediate portion 33 are welded to each other. In this manner, as illustrated in FIG. 6(a), the outer pipe 31c and the intermediate portion 33 are joined to each other by the welding portion W2. In this way, an integrated component in which the distal end portion 31 and the intermediate portions 32 and 33 are integrated with each other is formed. Next, in a case where the intermediate portions 32 and 33 are made of stainless steel, the obtained integrated component is heated to a predetermined temperature (for example, l,000°C or higher) in a heating furnace, and thereafter, is rapidly cooled. In this manner, the stainless steel is subjected to solution treatment.

[0060] Next, as illustrated in FIG. 6(a), the other end of the intermediate portion 32 and one end of the proximal end portion 34 are caused to face each other. In this state, the other end of the intermediate portion 32 and one end of the proximal end portion 34 are welded to each other. In this manner, as illustrated in FIG. 6(b), the intermediate portion 32 and the proximal end portion 34 are joined to each other by the welding portion W3. In this case, the other end of the intermediate portion 32 is located on the proximal end side of the cooling member 30 from the other end of the intermediate portion 33.

FP17-0783-00

Accordingly, a welding torch is less likely to be hindered by the intermediate portion 33 when the welding torch is directed between the other end of the intermediate portion 32 and one end of the proximal end portion 34. Next, the outer peripheral edge of the proximal end wall 34a is welded to the other end of the proximal end portion 34. [0061] Next, as illustrated in FIG. 6(b), the other end of the intermediate portion 33 and one end of the proximal end portion 35 are caused to face each other. In this state, the other end of the intermediate portion 33 and one end of the proximal end portion 35 are welded to each other. In this manner, as illustrated in FIG. 3, the intermediate portion 33 and the proximal end portion 35 are joined to each other by the welding portion W4.

[0062] Next, the internal wall 36 is inserted into a portion between the inner peripheral wall (the inner pipe 31b, the intermediate portion 32 and the proximal end portion 34) of the cooling member 30 and the outer peripheral wall (the outer pipe 31c, the intermediate portion 33, and the proximal end portion 35) of the cooling member 30. Next, the other end of the internal wall 36 is welded to the outer peripheral surface of the proximal end portion 34. Next, the other end of the proximal end portion 35 is welded to the outer peripheral surface of the internal wall 36. According to the above-described method, the cooling member 30 is completely manufactured.

[0063] Subsequently, the male screw Ms disposed on the outer peripheral surface of the main body portion 21 is screwed into the female screw Fs disposed in the distal end portion on the inner peripheral surface of the inner pipe 31b. In this manner, the nozzle tip

FP17-0783-00 is attached to the cooling member 30.

[0064] Subsequently, the fuel pipe 10 is inserted into the through-hole of the proximal end wall 34a, the through-hole 21a of the nozzle tip 20, and the cylinder hole 22a of the nozzle tip 20. In this manner, the distal end portion of the fuel pipe 10 is fitted to the nozzle tip 20 by clearance-fitting. In this way, the fuel pipe 10 is attached to the nozzle tip 20. Next, the inner peripheral surface of the through-hole of the proximal end wall 34a is welded to the outer peripheral surface of the fuel pipe 10. According to the above-described method, the gasification burner 1 is completely manufactured.

[0065] [Operation]

In the present embodiment as described above, the nozzle tip 20 and the cooling member 30 are screwed to each other by using the screws (the male screw Ms and the female screw Fs). Therefore, the nozzle tip 20 is very easily attached to and detached from the cooling member 30. Therefore, by preparing a plurality of types of the nozzle tips 20 having mutually different directions of the through-holes 21b through which the oxidant flows, it is possible to cope with a change in fuel types by simply replacing the nozzle tips 20 without remodeling the coal gasifier 100. Asa result, it is possible to handle various fuel types by means of a simple configuration.

[0066] In the present embodiment, the spacers 36a are disposed between the internal wall 36 and the distal end wall 31a, and the spacers 36b are disposed between the internal wall 36 and the proximal end portion 35. Therefore, the spacers 36a and 36b allow the spaces V2 and V3 to be secured between the internal wall 36, and the distal end

FP17-0783-00 wall 31a and the proximal end portion 35. This enables the coolant to flow smoothly inside the spaces V2 and V3.

[0067] In the present embodiment, the distal end of the fuel pipe 10 is exposed on the distal end surface S2 of the nozzle tip 20. Therefore, even if the fuel pipe 10, when in use, thermally expands due to the heat received from the partial oxidation section 102 and extends to the nozzle tip 20, the extension is not restricted by the nozzle tip 20. Therefore unnecessary stress can be prevented from being generated between the nozzle tip 20 and the fuel pipe 10. In addition, the fuel flows through the fuel pipe 10 without contacting the nozzle tip 20, and is discharged into the partial oxidation section 102, unlike a case where the fuel pipe 10 is attached to the nozzle tip 20 in a state where the distal end of the fuel pipe 10 remains inside the nozzle tip 20. This makes it possible to minimize the possibility that the nozzle tip 20 may be worn by contacting with the fuel.

[0068] In the present embodiment, in a case where the intermediate portions 32 and 33 are made of stainless steel subjected to solution treatment, the corrosion resistance of the stainless steel which is degraded by the welding between the intermediate portions 32 and 33 and the distal end portion 31 is recovered by the solution treatment. Therefore, the stress corrosion cracking of the cooling member 30 can be further prevented. The intermediate portions 32 and 33 and the proximal end portions 34 and 35 are also joined to each other by welding. Accordingly, if the proximal end portions 34 and 35 are made of stainless steel, the proximal end portions 34 and 35 are also degraded. However, as illustrated in FIG. 2, the gasification burner 1

FP17-0783-00 is attached to the partial oxidation section 102 via the insulation material 105, and the insulation material 105 covers most of the outer peripheral surface of the cooling member 30. Therefore, the high-temperature gas Gl generated in the partial oxidation section 102 hardly enters the vicinity of the joint portion between the intermediate portions 32 and 33 and the proximal end portions 34 and 35.

[0069] [Other Embodiments]

Hitherto, the embodiment according to the present disclosure has been described in detail. However, various modifications may be added to the above-described embodiment within the scope of the gist of the present invention. For example, as illustrated in FIG. 7, the fuel pipe 10 and the nozzle tip 20 may be screwed to each other by the screws (the male screw Ms and the female screw Fs), and the nozzle tip 20 and the cooling member 30 may be fitted to each other (for example, clearance-fit). In addition, as illustrated in FIG. 8, the nozzle tip 20 and the fuel pipe 10 may be screwed to each other by the screws (the male screw Ms and the female screw Fs), and the nozzle tip 20 and the cooling member 30 may be screwed to each other by the screws (the male screw Ms and the female screw Fs). That is, at least one of the portion between the nozzle tip 20 and the fuel pipe 10 and the portion between the nozzle tip 20 and the cooling member 30 is fastened by screwing.

[0070] As illustrated in FIG. 9, the distal end of the fuel pipe 10 may not be exposed on the distal end surface S2 of the nozzle tip 20. Specifically, the fuel pipe 10 may be attached to the nozzle tip 20 in a state where the distal end of the fuel pipe 10 remains inside the nozzle

FP17-0783-00 tip 20.

[0071] As illustrated in FIG. 10, the covering layer 37 may be located on the surface of the distal end portion 31 of the cooling member 30. In this case, the cooling member 30 does not have the intermediate portions 32 and 33. The inner pipe 31b and the proximal end portion 34 are directly joined to each other by the welding portion Wl, and the outer pipe 31c and the proximal end portion 35 are directly joined to each other by the welding portion W2. The covering layer 37 covers a region exposed outward in the surface of the distal end portion 31, the outer surface of the welding portion W2, and a region of the vicinity of the distal end portion 31 in the outer peripheral surface of the proximal end portion 35. For example, the covering layer 37 may be formed by means of overlaying. Since the covering layer 37 covers the outer surface and the vicinity of the welding portion W2, a region where the corrosion resistance is degraded due to the welding is protected by the covering layer 37. This enables stress corrosion cracking of the cooling member 30 to be further prevented.

[0072] In a form of FIG. 10, the covering layer 37 may be made of a nickel alloy in which the content of Ni with respect to the total mass of the distal end portion 31 is 40% by mass or more. The nickel alloy has high corrosion resistance. Accordingly, the covering layer 37 is less likely to suffer dew point corrosion. This enables stress corrosion cracking of the cooling member 30 to be further prevented. For example, the nickel alloy includes Inconel 718 and Alloy 718.

[0073] In a form of FIG. 10, the distal end portion 31 may be made of copper, and the proximal end portions 34 and 35 may be made of

FP17-0783-00 stainless steel. In this case, the copper, which has high thermal conductivity but low corrosion resistance, is covered with the covering layer 37. This enables stress corrosion cracking of the distal end portion 31 to be prevented by the covering layer 37 while heat exchange is promoted in the distal end portion 31 which is most likely to receive the heat transferred from the partial oxidation section 102. In addition, copper is cheaper than stainless steel. Accordingly, the cost of the cooling member 30 can be reduced.

[0074] A coefficient of thermal expansion (linear expansion coefficient) of the material configuring the fuel pipe 10 may be higher than a coefficient of thermal expansion (linear expansion coefficient) of the material configuring the nozzle tip 20. For example, the fuel pipe 10 may be made of SUS310S (average linear expansion coefficient of 0°C to 650°C is 17.5xl0'⁶/°C), and the nozzle tip 20 may be made of SUS430 (average linear expansion coefficient of 0°C to 650°C is 12.8xl0’⁶/°C). In this case, if the fuel pipe 10 and the nozzle tip 20, when in use, thermally expand due to the heat received from the partial oxidation section 102, the fuel pipe 10 is firmly fastened to the nozzle tip 20 since the fuel pipe 10 has the higher coefficient of thermal expansion. This makes it possible to prevent the oxidant from flowing out of both the clearances.

[0075] In the above-described embodiment, the coal gasifier 100 using the pulverized coal as the fuel has been described as an example. However, the present invention is also applicable to the gasification burner 1 of a plant using the other fuel other than the pulverized coal. Furthermore, the present invention is also applicable to a combustion

FP17-0783-00 burner used in a combustion furnace that combusts the pulverized fuel (solid fuel), a liquid fuel, or a gaseous fuel.

Reference Signs List [0076] 1: gasification burner (burner)

10: fuel pipe

20: nozzle tip

21b: through-hole (flow path)

30: cooling member

31: distal end portion

31a: distal end wall

31b: inner pipe (inner peripheral wall)

31c: outer pipe (outer peripheral wall)

32: intermediate portion (inner cylindrical portion; inner peripheral wall; proximal end portion)

33: intermediate portion (outer cylindrical portion; outer peripheral wall; proximal end portion)

34: proximal end portion (inner peripheral wall)

35: proximal end portion (outer peripheral wall)

36: internal wall

36a, 36b: spacer

37: covering layer

100: coal gasifier

Fs: female screw (screw)

Ms: male screw (screw)

S2: distal end surface

W1 to W4: welding portion

Claims

1. A burner comprising:

a fuel pipe through which a pulverized fuel flows;

a cylindrical cooling member through which a coolant internally circulates; and a cylindrical nozzle tip into which a distal end periphery of the fuel pipe is inserted, and which is inserted into a distal end periphery of the cooling member, wherein a cylinder wall of the nozzle tip is internally provided with an oxidant flow path penetrating the nozzle tip to extend along an axial direction of the nozzle tip, wherein at least one of a portion between the nozzle tip and the fuel pipe and a portion between the nozzle tip and the cooling member is fastened by screwing, and wherein a distal end of the fuel pipe reaches a distal end surface of the nozzle tip, and is exposed therefrom.

2. The burner according to claim 1, wherein one of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member is fastened by screwing, and wherein the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member is fitted.

3. The burner according to claim 2,

FP17-0783-00 wherein the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member is clearance-fitted so that a tolerance zone of a hole is any one of D to H and a tolerance zone of a shaft is any one of d to h, the tolerance zones being defined inJIS B 0401-1: 2016 (ISO286-1: 2010).

4. The burner according to claim 3, wherein a length of the clearance-fit on the other of the portion between the nozzle tip and the fuel pipe and the portion between the nozzle tip and the cooling member is 1 cm or longer.

5. The burner according to any one of claims 1 to 4, wherein a distal end portion of the cooling member is formed of a nickel alloy in which a content of Ni with respect to a total mass of the distal end portion is 40% by mass or more.

6. The burner according to any one of claims 1 to 5, wherein at least a distal end portion of the cooling member is connected to a proximal end portion by welding, and wherein a portion closer to the distal end portion in the proximal end portion is formed of stainless steel subjected to solution treatment.

7. The burner according to any one of claims 1 to 4, wherein a distal end portion of the cooling member is connected to a proximal end portion by welding, and wherein a covering layer is located on a surface of the distal end

FP17-0783-00 portion to cover a region including a welding portion between the distal end portion and the proximal end portion.

8. The burner according to claim 7, wherein the covering layer is formed of a nickel alloy in which a content of Ni with respect to a total mass of the distal end portion is 40% by mass or more.

9. The burner according to claim 8, wherein the distal end portion is formed of copper, and the proximal end portion is formed of stainless steel.

10. The burner according to any one of claims 1 to 9, wherein the cooling member includes a cylindrical outer peripheral wall, a cylindrical inner peripheral wall located inside the outer peripheral wall, a distal end wall connecting distal ends of the outer peripheral wall and the inner peripheral wall to each other, and a cylindrical internal wall located between the outer peripheral wall and the inner peripheral wall to be separated from the outer peripheral wall and the inner peripheral wall, and wherein spacers are disposed between the internal wall, and the distal end wall, the outer peripheral wall, or the inner peripheral wall.

11. The burner according to any one of claims 1 to 10,

FP17-0783-00 wherein a coefficient of thermal expansion of the fuel pipe is higher than a coefficient of thermal expansion of the nozzle tip.

12. A method of manufacturing a burner, comprising:

a first step of preparing a fuel pipe through which a pulverized fuel flows;

a second step of preparing a cylindrical cooling member through which a coolant internally circulates;

a third step of preparing a cylindrical nozzle tip in which an oxidant flow path penetrating to extend along an axial direction is disposed inside a cylindrical wall; and a fourth step of inserting a distal end of the fuel pipe into the nozzle tip so that a distal end of the fuel pipe reaches a distal end surface of the nozzle tip and is exposed therefrom, and inserting the nozzle tip into a distal end periphery of the cooling member, wherein the fourth step includes screwing on at least one of a portion between the nozzle tip and the fuel pipe and a portion between the nozzle tip and the cooling member.

13. The method according to claim 12, wherein the cooling member is obtained through a first sub-step of preparing a distal end portion of the cooling member configured so that one end of a double pipe is closed by a distal end wall and an inner pipe is longer than an outer pipe, an inner cylindrical portion corresponding to an inner peripheral wall of the cooling member and formed of stainless steel, and an outer cylindrical

FP17-0783-00 portion corresponding to an outer peripheral wall of the cooling member and formed of stainless steel, a second sub-step of welding the other end of the inner pipe and one end of the inner cylindrical portion to each other, after the first

5 sub-step, a third sub-step of forming an integrated component by welding the other end of the outer pipe and one end of the outer cylindrical portion to each other, after the second sub-step, and a fourth sub-step of (A) performing a solution treatment on

10 stainless steel forming the inner cylindrical portion and the outer cylindrical portion by heating the integrated component, or (B) forming a covering layer in a distal end periphery of the integrated component to cover a region including a welded location between the distal end portion and the outer cylindrical portion, after the third sub-step.