JP2737129B2 - Radiant tube sealed support structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a radiant tube as a heat source for heating the inside of a furnace, which has two penetrations, one and the other end of which are provided on one side wall of a furnace body. The present invention relates to a heat treatment furnace attached to a furnace body so as to protrude out of a furnace body from a hole, and more particularly, to a support structure for supporting a radiant tube with respect to the furnace body. (Prior Art) In this type of heat treatment furnace, the inner diameter of the through hole is formed slightly larger than the outer diameter of the radiant tube.
However, a gap formed between the through hole and the end of the radiant tube needs to be sealed in order to appropriately hold the atmosphere gas in the furnace. Therefore, conventionally, the radiant tube is sealed in a state in which the radiant tube is hermetically sealed using a flexible member having easy deformability in the axial direction to allow displacement in the axial direction when the radiant tube thermally expands in the axial direction. Various means are provided for supporting the end of the tube. (For example, see Japanese Utility Model Laid-Open No. 60-102241) However, in any of the means, the force for restraining the end of the radiant tube in a direction perpendicular to the axis of the end is large,
When the distance between the ends is increased due to the thermal expansion of the radiant tube, a large stress exceeding the allowable stress is applied to the radiant tube, causing a problem of causing permanent deformation or destruction thereof. (Problems to be Solved by the Invention) The present invention, apart from the above-mentioned conventional problems, not only allows deformation of the radiant tube in the axial direction but also increases the distance between the ends of the radiant tube. Provided is a sealed support structure for a radiant tube in which even if displacement occurs in a direction perpendicular to the axis of the end with respect to the radiant tube, the displacement can be permitted (absorbed) and permanent deformation or destruction of the radiant tube can be prevented. What you want to do. (Means for Solving the Problems) According to the present invention, two through holes having an inner diameter larger than an outer diameter of an end portion of a radiant tube are provided on one side wall of a hollow furnace body having a heat treatment space inside. Drill holes,
In the heat treatment space, an intermediate portion of the radiant tube is kept, and one and the other ends of the radiant tube are passed through the through holes, and portions of the ends protruding outside the furnace body are each Are supported by two support members, one end of which is hermetically fastened to the edge of each through-hole, and the other end of which is hermetically fastened around each end of the radiant tube. A radiant tube, wherein at least one of the supporting members includes a radiant tube having a flexure member having easy deformation in the axial direction for allowing displacement in the axial direction when the radiant tube thermally expands in the axial direction. In the hermetically sealed support structure, at least one of the support members is provided between one end and the other end of the radiant tube. To permit the axis perpendicular to the direction of displacement, it was allowed with a greatly deflection member axis perpendicular to the direction of deformation easiness compared to the deformation easiness of the axial direction at the end of the radiant tube. (Operation) When the radiant tube is heated, it is deformed in the axial direction by the thermal expansion, and the interval between one end and the other end is increased. The displacement of the end of the radiant tube relative to the furnace body due to the widening of the gap, that is, the displacement of the end in the direction perpendicular to the axial direction is absorbed by the bending member perpendicular to the axis in the support member. (Embodiment) Drawings showing an embodiment of the present application will be described below. First
In the drawing, reference numeral 1 denotes a heat treatment furnace, and a partial cross section is shown in the drawing. In the heat treatment furnace 1, reference numeral 2 denotes a hollow furnace body, and the inside thereof is a heat treatment space 3. Furnace body 2
As shown in FIG. 2, a heat insulating material 5 is lined with a furnace shell metal member 4. Reference numerals 7 and 8 denote through holes for inserting a radiant tube drilled in one side wall of the furnace body 2,
Each of the radiant tubes is formed to have an inner diameter larger than the outer diameter at the end. Next, reference numeral 10 denotes a radiant tube. The radiant tube 10 is formed in a U-shape as an example, but may be formed in a W-shape as shown in FIG. Examples of the radiant tube include a heat-resistant cast steel containing chromium or nickel as a main component such as SCH22, a super heat-resistant alloy such as MORE-2 (trade name),
Some are made of ceramics (often silicon carbide) and the like. In the radiant tube 10, reference numeral 11 denotes an intermediate portion, which is also called a heating source portion, and is located in the heat treatment space 3. 12, 13 are one end and the other end respectively,
The respective tips are projected outside the furnace body through the through holes 7, 8, respectively. These ends 12, 13 are also called a burner side end and an exhaust side end, respectively. 15 is the end 12
For example, a nozzle mix gas burner is used. 16 is a fuel (gas) receiving port, and 17 is a fuel air receiving port. Reference numeral 18 denotes an exhaust pipe attached to the end 13. Incidentally, a recuperator 19 for preheating the combustion air may be inserted into the end portion 13 in some cases. Next, 21 and 22 are support members that support portions protruding from the through-holes 7 and 8 to the outside of the furnace body at the ends 12 and 13 of the radiant tube 10, both of which are formed in an annular shape, and each end 21a , 22a are at the edge of the through holes 7, 8 in the furnace body 2, and the other ends 21b, 22b are at the respective ends 12, 13 of the radiant tube 10.
Each is hermetically fastened around. In the above configuration, the fuel gas supplied to the burner 15 is burned by the combustion air, and the burner 15 emits a flame toward the radiant tube 10. The high-temperature combustion gas generated by the combustion heats the heating source 11 to a high temperature in the process of passing through the inside of the heating source 11. As a result, the heating source unit 11 heats the heat-treated product in the heat-treating space 3 directly or indirectly through the gas by heating the atmosphere gas filled in the space 3. The combustion gas that has passed through the inside of the heating source 11 is discharged from the exhaust side end 13 through an exhaust pipe 18. In the above case, the fuel air to the burner 15 may be preheated by the recuperator 19. Next, in FIG. 2 showing in detail the support member 21 of the burner side end portion 12 as an example of the support members 21 and 22, reference numeral 24 denotes an axial bellows exemplified as an axial bending member.
It is formed in a cylindrical shape and has a property of being easily deformed in the direction of the axis 12a at the end portion 12 of the radiant tube. The one end 21a of the support member 21 is constituted by one end 24a of the bellows 24, and is fastened to the edge of the through hole 7 by fastening means 25. That is, reference numeral 26 denotes a mounting plate in the fastening means, and the plate 26 has one end 24a
Are hermetically sealed by welding means. A packing 27 is interposed between the plate 26 and the furnace shell 4 to maintain the airtightness between them. Numeral 28 indicates the presence of bolts and nuts for fastening the rate 26 to the furnace shell hardware 4. The mounting plate 26 may be mounted on a radiant tube mounting base 4a integrally provided with the furnace body 2 as shown in FIG. Next, 30 is a bellows in the direction perpendicular to the axis, which is exemplified as a flexible member in the direction perpendicular to the axis, formed in a disk shape, and in a direction perpendicular to the axis compared to the ease of deformation in the axial direction 12a at the end 12 of the radiant tube 10. Has the property of being easily deformable (spring constant in the axial direction> spring constant in the direction perpendicular to the axis). One end (outer peripheral end) 30a of the bellows 30 and the other end 24b of the bellows 24 are hermetically connected by welding means. The other end of the support member 21
Reference numeral 21b denotes the other end (inner peripheral end) 30b of the bellows 30 and is hermetically fixed around the end 12 of the radiant tube 10. The fastening is radiant tube 10
When the radiant tube 10 is made of ceramics, it is good to use an adhesive. 31 is crimped (or bonded) to the tip of the end 12
3 shows the burner mounting flange fastened by means. Next, the operation of the support member 21 having the above configuration will be described. In FIG. 1, when the exhaust end 13 of the radiant tube 10 is firmly attached to the furnace body 2 by the support member 22, when the heating source 11 is heated to a high temperature as described above, its thermal expansion causes the burner end. The portion 12 is displaced in the direction of the axis 12a and also displaced in a direction perpendicular to the axis 12a (in a direction away from the exhaust end 13). However, the axial displacement is absorbed by the deformation (elongation or contraction) of the bellows 24,
The displacement in the direction perpendicular to the axis is absorbed by the deformation of the bellows 30. Therefore, a large restraining force is not applied to the radiant tube 10, and its permanent deformation and destruction are prevented. When the burner side end 12 is displaced as described above, the force acting on the fastening portion of the bellows other end 30b with respect to the end periphery is:
There is only a force in the direction in which both are displaced (the bellows 30 absorbs most of the displacement in the direction perpendicular to the axis, and the force in that direction is not applied to the fastening portion). Therefore, even if the fixing is performed with an adhesive, the bonding strength is generally much higher in the direction in which the bonding surface is displaced than in the direction in which the bonding surface is peeled off at a right angle. The trouble is unlikely to occur. When the radiant tube 10 is formed of ceramics, its manufacturing accuracy is generally low. For example 170φ
There is an error of about ± 2 to 3 mm (as cast and baked skin) (approaching to precision by processing or polishing leads to a large cost increase). However, in this example, since the bellows 30 are used as described above, the bellows 30 can absorb the error. Therefore, the outer peripheral surface of the end of the radiant tube 10 and the inner peripheral end 30b of the bellows 30 can be adhered in close contact with each other, and high adhesive strength can be obtained. 2, the burner is directly attached to the burner side end 12 of the radiant tube 10 using the flange 31. Therefore, if the burner is mounted such that the center axis of the burner coincides with the axis 12a of the end portion 12, no displacement occurs between the two during use. This is very effective in preventing the radiant tube from overheating. The support member having the structure shown in FIG. 2 can be used at the exhaust end 13 or at both ends 12, 1 on the burner side and the exhaust side.
3 may be used. Next, FIG. 3 shows an example of the structure of the support member 22 at the end on the exhaust side. In the figure, reference numeral 33 denotes a cylinder forming a base. The one end 22a of the support member 22 is
And is fixed to the edge of the through-hole 8 by the fastening means 35 having the same configuration as the fastening means 25. 36 is mounting plate, 37 is packing,
38 indicates the presence of a fastening member. 40 radiant tube
10 is a flexible member having easy deformation in the axial direction for allowing axial displacement when thermally expanded in the axial direction, and as a flexible member in a direction perpendicular to the axis 13a of the end portion 13. The exemplified flexible tube in the direction perpendicular to the axis has the property that the end portion 13 of the radiant tube 10 is easily deformable in the axial direction 13a, and the deformability in the direction perpendicular to the axis is larger than the deformability. One end 40a of the flexible tube 40 and the other end 33b of the cylindrical body 33 are connected by connecting means 41. That is, a ring-shaped tube fixing hardware 42 is fixed to the other end 33b by welding, a ring-shaped tube exhaust end flange 43 is fixed to the one end 40a, and a packing 44 is provided between the two. Are interposed in a polymerized manner. Reference numeral 45 indicates the presence of a fastening member. The other end of the support member 22
22b is configured with the other end 40b of the flexible tube 40,
The bellows 30 is fixed around the end 13 in the same manner as the other end 30b of the bellows 30. Reference numeral 46 denotes a mounting flange for the exhaust pipe. In the support member 22 having the above configuration, when the end portion 13 is displaced in a direction perpendicular to the axis 13a with respect to the furnace body 2, the displacement can be absorbed by the flexible tube 40, and a large restraining force is exerted on the radiant tube 10. Can be prevented. The support member having the structure shown in FIG. 3 may be used at the burner side end portion 12. Next, FIG. 4 shows a different example of a connection structure between the other end 24b of the axial bellows 24 and one end 30a of the bellows 30 perpendicular to the axis in FIG. 2. Each end 24b, 30a is individually connected to an intermediate flange. 48 shows an example of connection. According to such a connection structure, even if each of the bellows 24 and 30 is formed to be thin, both can be connected accurately. 49 indicates the presence of tie bolts. Next, FIG. 5 shows a different configuration example of the bending member in the direction perpendicular to the axis line. The member is formed by welding a plurality of annular elements 50a, 50b, 50c,. As shown in the figure, they are connected sequentially. (Effects of the Invention) As described above, in the present invention, the through holes 7 and 8 in the furnace body 2 are formed to be larger than the outer diameter of the end of the radiant tube 10 so that the end of the radiant tube 10 is The radiant tube 10 can be mechanically supported with respect to the furnace body 2 by the support members 21 and 22 even if the radiant tube 10 can be displaced in the direction and the direction perpendicular to the axial direction thereof. There is an effect that the proper position of the middle part of the tube can be held. Moreover, in this state, the heat treatment space in the furnace can be hermetically sealed by the support members 21 and 22, and there is an effect that the atmosphere gas in the heat treatment space can be appropriately maintained. Moreover, even in the case where the radiant tube 10 is supported in a state where the inside of the furnace is sealed as described above, when the radiant tube is heated and the space between both ends 12, 13 is widened due to the thermal expansion, the radiant with respect to the furnace body due to the widening of the space. There is a feature that the displacement of the end portion 12 of the tube can be absorbed by the flexible member 30 whose deformability in the direction perpendicular to the axis is greater than that in the axial direction. This means that the restraining force on the radiant tube can be reduced, and there is an effect that permanent deformation or destruction of the radiant tube can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, FIG. 1 is a partially cutaway view of a heat treatment furnace, FIG. 2 is a sectional view showing a detailed structure of a support member at a burner side end, FIG. 3 is a sectional view showing a detailed structure of a support member at an exhaust side end, FIG. 4 is a partial view showing a different example of a connection structure between an axial bellows and a bellows at right angles to the axis, and FIG. FIG. 6 is a partial view showing a different example of the member, and FIG. 6 is a view showing a different example of the shape of the radiant tube. 2. Furnace body, 7, 8 through hole, 10 radiant tube, 12, 13 end portion, 21, 22 support member, 30 bending member perpendicular to the axis.

Claims (1)

(57) [Claims] Two through-holes each having an inner diameter larger than the outer diameter of the end portion of the radiant tube are formed in one side wall of the hollow furnace body in which the inside is a heat treatment space. While leaving an intermediate portion of the tube, one end and the other end of the radiant tube penetrate through each of the through holes, and a portion of the end projecting outside the furnace body has one end of each of the through holes. The radiant tube is supported by two support members which are hermetically fastened to the edge of the hole and the other end of which is airtightly fastened around each end of the radiant tube, and at least one of the support members supports the radiant tube. The radiant tube is provided with a flexible member having easy deformation in the axial direction for allowing axial displacement when the radiant tube thermally expands in the axial direction. In the closed support structure of the tube, at least one of the support members is provided with at least one of the support members in order to allow a displacement in a direction perpendicular to an axis between one end and the other end of the radiant tube. A radiant tube hermetic support structure, characterized in that the radiant tube has a flexible member that has greater deformability in the direction perpendicular to the axis than in the axial direction at the end of the radiant tube.