JP2001108390A - Multi-tube type heat exchanger and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazed multi-tube type heat exchanger having superior quality in which poor brazing or poor connection between a tube sheet and a heat transfer pipe caused by thermal expansion at the time of brazing is not produced. SOLUTION: There is provided a multi-tube type heat exchanger having such a structure as one in which each of barrel tubes, tube sheets arranged near both ends of inner walls of the barrel tubes, a group of heat transfer tubes supported by the tube sheets and end caps arranged between both ends of the barrel tubes is integrally brazed to each other. At least, one end of the heat transfer tube is expanded into a funnel shape and the funnel-shaped and expanded tube is brazed under a state in which it is being projected outside the tube sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multitubular heat exchanger used for general industry, automobiles, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a multi-tube heat exchanger used for cooling EGR gas or the like, a first heat exchange fluid inlet 11-1 and an outlet 11-2 are provided at both ends as shown in FIG. Inside the body tube (shell) 11, both end portions of the heat transfer tube (tube) group 12 are fixed to a sheet metal tube sheet 13 by brazing, while the tube sheet 13 has an outer peripheral end portion formed on the inner wall of the body tube 11. And an end cap (bonnet) 14 having a second heat exchange fluid inlet 14-1 and an outlet 14-2 provided at both ends of the body tube 11. No.

[0003] A multi-tube heat exchanger having a brazing structure as a whole having such a structure has a first heat exchange fluid inlet 1 at both ends.
Body tube 11 provided with 1-1 and outlet 11-2, tube sheet 13 provided near both ends of the inner wall of body tube 11, heat transfer tube group 12 supported by the tube sheet, and body tube 11 After assembling the end cap 14 provided with the second heat exchange fluid inlet and outlet disposed at both ends of the brazing furnace, the whole is charged into a brazing furnace and brazed in the furnace.

[0004]

However, in the case of a conventional multi-tube heat exchanger and a method of manufacturing the same, the whole heat exchanger body is assembled, then the whole is charged into a brazing furnace and brazed in the furnace. However, there are problems described below. That is, the brazing furnace is heated mainly by radiant heat from a heating element surrounding the work. Therefore, in the case of brazing the whole after assembling the heat exchanger main body, first, the heat exchanger is radiatively heated from the outer surface in the furnace, and the body tube 11 thermally expands. When the body tube 11 first thermally expands, the position of the heat transfer tube 12-1 supported by the tube sheet 13 brazed to the body tube 11 in the tube axis direction changes, or the heat transfer tube 12-1 The phenomenon of falling off occurs. FIGS. 7A and 7B are explanatory diagrams, in which FIG. 7A shows an example in which the position of the heat transfer tube 12-1 in the tube axis direction with respect to the tube sheet 13 changes, and FIG.
The following are examples of more omissions. That is, FIG.
In the case of (a), in a state where the heat exchanger body is assembled,
For example, the inner surface of the through hole 13-1 of the right tube sheet 13 and the heat transfer tube 1 supported through the tube sheet
When the coefficient of friction between the outer surfaces of 2-1 is larger than the left side, the tube sheet 13 on the right side moves outward due to the thermal expansion of the body tube 11 in the furnace, so that the heat transfer tube 12-1 is pulled to the right side. As a result, the left end portion of the heat transfer tube 12-1 sinks into the through hole 13-1 of the tube sheet 13 on this side, and in this state, when cooling after brazing is performed, the body tube 1 With the shrinkage, the right end of the heat transfer tube 12-1 protrudes more than the set length from the tube sheet 13, and the left end is further submerged in the through hole 13-1 of the tube sheet 13 to complete the brazing. . Therefore, the tube sheet 1
The left end of the heat transfer tube 12-1, which has been brazed in a state where it is immersed in the through hole 13-1, has a poor brazing,
On the other hand, the right end protrudes beyond the tube sheet 13 by a set length or more. In the case of FIG. 7 (b), when the heat exchanger main body is assembled, the friction between the right tube sheet 13 and the outer surface of the heat transfer tube 12-1 penetrated and supported by the tube sheet is the same as described above. When the coefficient is larger than the left side, the tube sheet 13 on the right side moves outward with the thermal expansion of the body tube 1 in the furnace, so that the heat transfer tubes 12
If -1 is pulled to the right and the amount of movement is large, the left end of the heat transfer tube 12-1 falls out of the through hole 13-1 of the tube sheet 13 on this side as shown in the figure.

The present invention has been made to solve such a problem of the prior art. By forming a trumpet-shaped expanded portion at the end of each heat transfer tube, the brazing of the tube sheet and the heat transfer tube is poor. High-quality multi-tube heat exchanger with tube tube and heat transfer tube group well brazed, heat transfer tube protruding from tube sheet almost at set length It seeks to provide a way.

[0006]

According to the present invention, as a means for solving the above-mentioned problems in the prior art, the heat transfer tube is formed by forming a trumpet-shaped expanded portion at at least one open end of each heat transfer tube. The purpose is to prevent the heat transfer tube from fluctuating due to expansion and from falling off from the tube sheet.
An embodiment of the present invention comprises a body tube provided with a first heat exchange fluid inlet and an outlet at both ends, a tube sheet provided near both ends of an inner wall of the body tube, a heat transfer tube group supported by the tube sheet, and In the multi-tube heat exchanger, end caps provided with second heat exchange fluid inlets and outlets provided at both ends of the body tube are integrated by brazing, respectively. At least one end is expanded in a trumpet shape, and the trumpet-shaped expanded portion is brazed in a state of protruding outside the tube sheet. Further, the second embodiment is characterized in that a body tube provided with a first heat exchange fluid inlet and an outlet at both ends, a tube sheet provided near both ends of an inner wall of the body tube, and a transmission supported by the tube sheet. A multi-tube heat exchanger having a structure in which a heat tube group and end caps provided with second heat exchange fluid inlets and outlets disposed at both ends of the body tube are respectively integrated by brazing. In the manufacturing method, at least one end of the heat transfer tube is expanded in a trumpet shape, and the heat transfer tube is assembled such that the trumpet-shaped expanded portion projects outside the tube sheet.
Thereafter, the whole is brazed in a furnace.

In the present invention, the trumpet-shaped expanded portion is provided on at least one end of the heat transfer tube due to the movement of the heat transfer tube in the tube axial direction accompanying the thermal expansion of the body tube when the heat exchanger body is heated by the brazing furnace. This is to prevent poor brazing with the tube sheet and dropout from the tube sheet. Here, the tube axial length and the opening angle of the trumpet-shaped expansion portion of the heat transfer tube will be appropriately determined according to the diameter, length, material, etc. of the heat transfer tube. Has an outer diameter increased by 4 to 20%, preferably about 6 to 10% of the tube diameter, and has an opening angle of 30 to 75 °, preferably 45 to 75%.
About 60 ° is appropriate. Further, in the case of a heat transfer tube provided with a trumpet-shaped expanded portion at both ends, the heat transfer tube is thinned or broken by a tensile force in directions opposite to each other which is generated due to thermal expansion of the body tube. Set the interval at the lower part of the neck of the trumpet-shaped expanded portion at room temperature.

[0008]

FIG. 1 is a cross-sectional plan view showing an embodiment of a multi-tube heat exchanger according to the present invention, omitting a central portion, and FIG.
FIG. 3 is an enlarged sectional view showing a main part of the same apparatus, FIG. 3 is a view corresponding to FIG. 2 showing another embodiment of the present invention, and FIG. 4 is a method for manufacturing the multi-tubular heat exchanger shown in FIGS. (A) is a cross-sectional view showing a tube sheet and a part of the heat transfer tube after assembling the multi-tube heat exchanger and before charging the brazing furnace, omitting a central portion of the heat transfer tube; ) Is a view (a) corresponding to the state of the above multi-tube heat exchanger during heating in a furnace, and (c) is a view (a) of the same multi-tube heat exchanger after cooling. FIG. 5 and FIG. 5 are explanatory views showing a method of manufacturing the multitubular heat exchanger shown in FIG.
Fig. 2 is a cross-sectional view of the tube sheet and a part of the heat transfer tube after the assembly of the multi-tube heat exchanger and before charging the brazing furnace, omitting a central portion of the heat transfer tube. (A) equivalent view showing the state of the vessel during heating in the furnace, (c) is a view (a) equivalent view showing the state of the same multi-tube heat exchanger after cooling, and 1 is a body tube, 1-1 is a first heat exchange fluid inlet, 1-2 is a first heat exchange fluid outlet, 2 is a heat transfer tube group, 2-1A and 2-1B are heat transfer tubes, 2-1AR and 2-1BR are trumpet-shaped expanded tubes. , 3 is a tube sheet, 3-1 is a through hole, 4 is an end cap, 4
-1 is a second heat exchange fluid inlet, and 4-2 is a second heat exchange fluid outlet.

The multi-tubular heat exchanger of the present invention shown in FIGS. 1 and 2 uses a heat transfer tube 2-1A provided with a trumpet-shaped expanded portion 2-1AR on only one side of a tubular body, and has a structural advantage. Is similar to the conventional device shown in FIG. That is, inside the body tube 1 provided with the first heat exchange fluid inlet 1-1 and the outlet 1-2 at both ends, both ends of the heat transfer tube group 2 are fixed to the sheet metal tube sheet 3 by brazing. The tube sheet 3 is arranged with its outer peripheral end fixed to the inner wall of the body tube 1 by brazing, and a second heat exchange fluid inlet 4-1 and an outlet 4-2 are provided at both ends of the body tube 1. The end cap 4 is fixed and the trumpet-shaped expanded portion 2-1 is formed.
The AR and the straight pipe end on the opposite side are brazed in a state of protruding outside the tube sheet 3. Therefore, in the case of this multi-tube heat exchanger, the tube sheet 3
And the heat transfer tube group 2 are all brazed well, and the trumpet-like expanded portion 2- of the heat transfer tube 2-1A from the tube sheet 3 is formed.
The projecting amount of the 1AR and the end of the straight tube on the opposite side is also brazed with a substantially set length. here,
As the material of the heat transfer tube, SUS304, SUS304
Austenitic stainless steel such as L, SUS316, SUS316L, and SUS321 is used, and the outer diameter is 6.35 mm or 5.00 mm, and the length is 120 to 60.
Many are about 0 mm, but there is no particular limitation on the diameter, wall thickness or length. The body tube 1 and the tube sheet 3 are also made of the same material as the heat transfer tube. Examples of the brazing material used for fixing the heat transfer tube group 2 and the tube sheet 3 in the multi-tube heat exchanger of such a material include Cr 7 wt%, B 3 wt%, Si
This is a Ni-based brazing material comprising 4 wt%, Fe 3 wt%, and the balance Ni.

Trump-like expanded portion 2-1A of heat transfer tube 2-1A
As described above, the length l and the opening angle θ of the tube axial direction of R are determined as appropriate according to the diameter, length, material, and the like of the heat transfer tube. The outer diameter increases by 4 to 20%, preferably 6 to 10%, particularly preferably about 8% of the tube diameter, and the opening angle θ is 30 to 75 °, preferably 45 to 60 °, particularly preferably. About 50 ° is appropriate. In the case of the heat transfer tube 2-1A, brazing is performed in a state where the lower neck portion of the trumpet-shaped expanded portion 2-1AR is in contact with the tube sheet 3.

The multi-tube heat exchanger shown in FIG. 3 has a heat transfer tube 2 having trumpet-shaped expanded portions 2-1BR provided at both ends of the tube.
1B, and in this case, the trumpet-shaped expanded portions 2-1BR provided at both ends are brazed in a state of protruding outside the tube sheet 3, respectively. Therefore, in the case of this multi-tube heat exchanger, as in the case shown in FIGS. 1 and 2, the tube sheet 3 and the heat transfer tube group 2 are all brazed well, and the heat transfer tube 2- 1B
The projecting amounts of the trumpet-shaped expanded portions 2-1BR at both ends of each of them are also brazed with substantially the set length.

Next, a method for manufacturing the above-mentioned multi-tube heat exchanger according to the present invention will be described with reference to FIGS. FIG.
FIG. 3 is an explanatory view of a method of manufacturing the multi-tube heat exchanger shown in FIGS. 1 and 2 configured by using a heat transfer tube 2-1A provided with a trumpet-shaped expanded portion 2-1AR on only one side of the tube. That is, first, the body tube 1 provided with the first heat exchange fluid inlet 1-1 and the outlet 1-2 at both ends, the tube sheet 3 provided near both ends of the inner wall of the body tube 1, and the tube sheet 3 An end cap 4 provided with a supported heat transfer tube group 2 and second heat exchange fluid inlets 4-1 and outlets 4-2 provided at both ends of the body tube 1 is assembled. At this time, the heat transfer tube 2-1
The trumpet-shaped expanded portion 2-1AR of A is formed before assembling, or is formed by expanding the diameter after passing through the through hole 3-1 of the tube sheet 3 in a straight pipe state during assembling. The heat transfer tube 2-1A has a trumpet-shaped expanded portion 2-1A.
The straight portion is slidably supported in the through hole 3-1 of the tube sheet 3 so that the tube end portions on the opposite side to the R project outside the tube sheet 3 and assembled.

Subsequently, the assembled tube heat exchanger is charged into a brazing furnace and heated to a predetermined temperature. As the multitubular heat exchanger is heated, the body tube 1 thermally expands, and the tube sheets 3 on both sides brazed to the inner wall surface of the body tube 1 due to the thermal expansion of the body tube 1 are shown in FIG. It moves outward as shown in FIG. At this time, the surface roughness of the through hole 3-1 of the tube sheet 3 of the trumpet-shaped expanded portion 2-1AR and the surface roughness of the trumpet-shaped expanded portion 2-1AR of the heat transfer tube 2-1A are determined by changing the through hole 3-1 of the opposite side. Friction between the through-hole 3-1 and the heat transfer tube 2-1A is made slightly higher than the heat transfer tube 2-1A or by making the diameter of the through-hole 3-1 on the side of the trumpet-shaped expanded portion 2-1AR slightly smaller. The coefficient is increased, and the lower part of the neck of the trumpet-shaped expansion portion 2-1AR formed at one end of the heat transfer tube 2-1A abuts on the tube sheet 3, whereby the tube sheet 3 is pulled to the left, and at the same time, the trumpet-shaped expansion tube is expanded. The end of the straight pipe on the opposite side (right side) to the part 2-1AR is also moved outward by the tube sheet 3 on this side, so that the length of the left side is equal to the total length of the movement and the length pulled to the left side. Projection amount from tube sheet 3 Less. In addition, even if the coefficient of friction with the through hole 3-1 and the heat transfer tube 2-1A on the opposite side to the trumpet-shaped expanded portion 2-1AR is large, the lower part of the neck of the trumpet-shaped expanded portion 2-1AR is attached to the tube sheet 3. Because of the contact, the heat transfer tube 2-1A moves to the trumpet-shaped expanded portion 2-1AR. After the heating in the furnace is completed, the entire cooling is performed. In this cooling process, the body tube 1 contracts in the opposite direction to the heating, and the tube sheets 3 on both sides move inward with the contraction. After cooling, as shown in FIG. 4 (c), the tube sheet 3 and the heat transfer tube 2-1A are brazed almost in an assembled state before being charged into a brazing furnace (FIG. A). Therefore, according to this method, when the heat exchanger main body is heated by the brazing furnace, the brazing of the tube sheet 3 with the tube sheet 3 due to the axial movement of the heat transfer tube 2-1A due to the thermal expansion of the body tube 1, It is possible to completely prevent falling off from the sheet.

Next, a trumpet-shaped expanded portion 2 is provided at both ends of the tube.
The method of manufacturing the multi-tubular heat exchanger shown in FIG. 5 constituted by using the heat transfer tubes 2-1B provided with 1BR will be described. In the case of the multi-tubular heat exchanger, as described above, the trumpet-shaped expansion section is used. The length of the heat transfer tube 2-1B provided with 2-1BR is set. That is, the trumpet-shaped expanded portion 2-1BR at room temperature is previously set to such an extent that the heat transfer tube 2-1B is not thinned or broken due to tensile forces in directions opposite to each other, which are generated due to the thermal expansion of the body tube 1. Of the lower neck distance L is set. The assembly of the heat transfer tube 2-1B and the tube sheet 3 of the multi-tube heat exchanger is performed by the length having the neck lower interval L of the trumpet-shaped expanded portion 2-1BR in consideration of the tensile force accompanying the thermal expansion of the body tube 1. Is slidably penetrated through the through hole 3-1 of the tube sheet 3 and protrudes outward from the tube sheet 3 by a predetermined length, and then a trumpet-shaped expanded portion 2-1 is provided at both tube ends.
BR is formed (FIG. A). After assembling the tube sheet 3 with the heat transfer tube 2-1B in which the trumpet-shaped expanded portion 2-1BR is formed at one end of the tube in advance, the trumpet-shaped expanded portion 2-1BR is formed at the other end of the tube. It goes without saying that this may be done. In any case, the trumpet-shaped expanded portion 2-1BR is formed so as to obtain the above-described neck lower portion distance L. That is, the trumpet-shaped expanded portion 2-1BR is formed such that the tube sheet 3 is located inside the lower part of the neck of the trumpet-shaped expanded portion 2-1BR at both ends by a length in consideration of the amount of thermal expansion of the body tube 1. I do.

Subsequently, the multi-tube heat exchanger assembled using the above-described heat transfer tubes 2-1B is charged into a brazing furnace and heated to a predetermined temperature. As the shell-and-tube heat exchanger is heated, the body tube 1 first thermally expands, and the tube sheets 3 on both sides brazed to the inner wall surface of the body tube 1 as the body tube 1 expands. It moves outward as shown in FIG. At this time, the heat transfer tube 2-1B has trumpet-shaped expanded portions 2- formed at both ends thereof.
The tube sheet 3 is moved by the lower part of the neck of one of the 1BRs abutting on the tube sheet 3, but the tube sheet 3 is pulled by the tube sheet 3 in directions opposite to each other. Is set in advance so as not to be thin or torn, so that the heat transfer tube 2-1B is subjected to an excessive tensile force, so that the heat transfer tube 2-1B is subjected to an excessive tensile force. The heat tube 2-1B does not become thin or torn. After cooling, as shown in FIG.
During the cooling process, the body tube 1 contracts in the opposite direction to that during heating, and the tube sheets 3 on both sides move inward with the contraction, so that the tube sheet 3 and the heat transfer tubes 2-1B are almost mounted in a brazing furnace. It is brazed in a state after assembly (FIG. A) before entering. Therefore, also in the present embodiment, poor brazing with the tube sheet 3 due to the axial movement of the heat transfer tube 2-1B due to the thermal expansion of the body tube 1 when the heat exchanger body is heated by the brazing furnace, It is possible to completely prevent falling off from the sheet.

[0016]

As described above, in the multi-tube heat exchanger according to the present invention, the tube sheet and the heat transfer tube group are all formed by forming a trumpet-shaped expanded portion at at least one end of each heat transfer tube. It is excellent in quality in that it is brazed well and the amount of protrusion of the heat transfer tube from the tube sheet has a substantially set length. In addition, according to the method of the present invention, the brazing of the heat transfer tube to the tube sheet due to the axial movement of the heat transfer tube due to the thermal expansion of the body tube, and the heat transfer tube falling out of the tube sheet are caused only by providing the heat transfer tube with the expanded portion. Therefore, an excellent effect that a high-quality multi-tubular heat exchanger can be manufactured without incurring an increase in cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view showing one embodiment of a multitubular heat exchanger according to the present invention, omitting a central portion.

FIG. 2 is an enlarged cross-sectional view showing a main part of the same device.

FIG. 3 is a diagram corresponding to FIG. 2, showing another embodiment of the present invention.

4A and 4B are explanatory views showing a method for manufacturing the multitubular heat exchanger shown in FIGS. 1 and 2, wherein FIG. 4A shows a tube sheet and a transmission before assembling a multitubular heat exchanger and before charging a brazing furnace; Sectional view showing a part of a heat tube omitting a central portion of the heat transfer tube, (b) is a diagram (a) equivalent diagram showing a state of the above-described multi-tube heat exchanger during heating in a furnace,
(C) is a figure (a) equivalent figure which shows the state after cooling of the same tube type heat exchanger same as the above.

5A and 5B are explanatory views showing a method for manufacturing the multitubular heat exchanger shown in FIG. 3; FIG. 5A shows one example of a tube sheet and a heat transfer tube after assembling the multitubular heat exchanger and before charging a brazing furnace; FIG. 2B is a cross-sectional view of the heat transfer tube with the central portion omitted, (b) is a diagram showing the state of the above-described multi-tube heat exchanger when heated in a furnace, and (c) is a diagram corresponding to FIG. It is a figure (a) equivalent figure showing a state after cooling of a tube type heat exchanger.

FIG. 6 is a cross-sectional plan view showing an example of a conventional multi-tube heat exchanger to which the present invention is applied, omitting a central portion.

FIG. 7 is a view showing an example of a state of attachment of a tube sheet and a heat transfer tube in a conventional method of manufacturing a multi-tube heat exchanger, and FIG. FIG. 3B is a partially omitted cross-sectional view showing an example in which a heat transfer tube has dropped out of a tube sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body pipe 1-1 1st heat exchange fluid inlet 1-2 1st heat exchange fluid outlet 2 Heat transfer tube group 2-1A, 2-1B Heat transfer tube 2-1AR, 2-1BR Trump-shaped expansion part 3 Tube sheet 3- DESCRIPTION OF REFERENCE NUMERALS 1 through hole 4 end cap 4-1 second heat exchange fluid inlet 4-2 second heat exchange fluid outlet

Claims (2)

[Claims] 1. A body tube provided with a first heat exchange fluid inlet and an outlet at both ends, a tube sheet provided near both ends of an inner wall of the body tube, a heat transfer tube group supported by the tube sheet, and In the multi-tube heat exchanger, end caps provided with second heat exchange fluid inlets and outlets provided at both ends of the body tube are integrated by brazing, respectively. Characterized in that at least one end of the tube is expanded in a trumpet shape, and the trumpet-shaped expanded portion is brazed in a state protruding outside the tube sheet. 2. A body tube provided with a first heat exchange fluid inlet and an outlet at both ends, a tube sheet provided near both ends of an inner wall of the body tube, a heat transfer tube group supported by the tube sheet, and An end cap provided with a second heat exchange fluid inlet and an outlet provided at both ends of the body tube, the method of manufacturing a multi-tube heat exchanger having a structure integrated by brazing, respectively. At least one end of the heat transfer tube is expanded in a trumpet shape, assembled so that the trumpet-shaped expanded portion protrudes outside the tube sheet, and then brazed in the furnace as a whole. Production method.