JP2001255094A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger where the separation of the welded section of a heat conductive tube can be repaired easily. SOLUTION: In a heat exchanger which has stored many pieces of heat conductive tubes 4 extending over a top tube plate 2 and a bottom tube plate 3, a supporting tube 17 which has a projection 19 at the inner face with a larger bore than the heat conductive tube 4 is fixed to the top tube plate 2, a heat conductive tube 4 whose top end is enlarged in diameter is passed in this supporting tube 17, and the top end of the supporting tube 17 and the top end of the heat conductive tube 4 are welded together. Even if the weld 20 between the supporting tube 17 and the heat conductive tube 4 peels off, the diameter- expanded part 4a of the heat conductive part 4 is hooked by the projection 19. Therefore, the heat conductive tube 4 never drops, and it can be repaired merely by welding the top of the supporting tube 17 and the top of the heat conductive tube 4 again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-tube heat exchanger used for preheating air sent to a cupola.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, in a cupola C for melting a cast material, a combustion gas discharged from the cupola C is further heated in a combustion chamber F as shown by a solid line in the figure. To heat exchangers H ₁ and H ₂ sequentially,
With discharged into the atmosphere by the blower B _1, as indicated by broken lines in the figure, the cold air introduced by the blower B ₂ successively preheated by the combustion gases through a heat exchanger H _2, H _1,
Equipment for feeding into Cupola C is used.

[0003] The heat exchanger H _1, as shown in FIG. 8,
Inside the body 50, a number of heat transfer tubes 53 are accommodated extending over the upper tube sheet 51 and the lower tube sheet 52, and the high-temperature combustion gas passes through the heat transfer tubes 53 from the gas supply chamber 54 above the upper tube sheet 51. The gas flows to the gas discharge chamber 55 below the lower tube sheet 52, and the body 50
The structure is such that low-temperature air flowing in from the lower air inlet 56 absorbs heat from the combustion gas through the wall of the heat transfer tube 53 while meandering by the baffle plate 57, and is sent out from the upper air outlet 58 of the body 50. It has become.

[0004] As shown in FIG. 9, the upper end of the heat transfer tube 53 penetrates the upper tube sheet 51 and is fixed to the upper tube sheet 51 by welding at a welding portion 59. As shown in FIG. 10, the lower end of the heat transfer tube 53 is slidably inserted into the lower tube sheet 52, and the gap is sealed with a packing 60.

[0005]

Incidentally, the above-mentioned welded portion 59 is easily corroded by the action of a high-temperature combustion gas, and if this corrosion progresses, the welded portion 59 may peel off and the heat transfer tube 53 may fall. In such a case, repair is very difficult with a structure in which the heat transfer tube 53 is directly welded to the upper tube sheet 51.

Accordingly, an object of the present invention is to provide a heat exchanger in which a welded portion of a heat transfer tube hardly peels off and can be easily repaired even if it peels off in a multi-tube heat exchanger.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a heat exchanger in which a plurality of heat transfer tubes extending between an upper tube sheet and a lower tube sheet are housed in a body. A support tube having a diameter larger than the heat tube and having a projection on the inner diameter surface is fixed to the upper tube plate, a heat transfer tube having an enlarged upper end is inserted into the support tube, and the upper end of the support tube and the upper end of the heat transfer tube are connected. Welded.

[0008] With this configuration, even if the welded portion between the support tube and the heat transfer tube is separated, the enlarged diameter portion of the heat transfer tube is caught by the projection. It can be repaired simply by welding the upper end of the heat transfer tube again.

Further, when a cooling chamber is provided below the upper tube sheet, the welded portion is cooled and its corrosion is suppressed. When a bellows is interposed between the body and the upper tube sheet, the difference in thermal expansion between the body and the heat transfer tube is obtained. Is absorbed, the load on the welded portion is reduced, and peeling of the welded portion is prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in a heat exchanger H, a plurality of heat transfer tubes 4 extending between an upper tube sheet 2 and a lower tube sheet 3 are accommodated in a body 1 of the heat exchanger H. The heat transfer tubes 4 pass through a plurality of baffle plates 5 provided alternately.

A gas supply chamber 6 is provided above the upper tube sheet 2, and a gas discharge chamber 7 is provided below the lower tube sheet 3, respectively.
The high-temperature combustion gas flows into the heat transfer tube 4 from the gas supply chamber 6 and is discharged to the gas discharge chamber 7.

A blower inlet 8 is provided at a lower portion of the body 1 and a blower outlet 9 is provided at an upper portion, and the low-temperature air flowing from the blower inlet 8 is meandered by the baffle plate 5 while the heat transfer tube 4 is formed.
The heat is absorbed from the combustion gas through the pipe wall of, and is sent out from the blowing outlet 9.

A bellows 10 is provided between the body 1 and the upper tube sheet 2.
The bellows 10 absorbs expansion and contraction of the heat transfer tube 4 to prevent air leakage. The lower tube sheet 3 is fixed to a lower portion of the body 1, and a gap between the lower tube sheet 3 and the heat transfer tube 4 is sealed by a packing 11.

A cooling chamber 12 is provided below the upper tube sheet 2 and partitioned by a partition wall 12a. Cooling air is supplied from a cooling air supply pipe 13 to the cooling chamber 12. The distal end of the cold air supply pipe 13 is slidably inserted into a short pipe 14 attached to the upper tube sheet 2 to absorb the elevation of the upper tube sheet 2.

The refractory mortar layer 1 is provided at the bottom of the gas supply chamber 6.
5 is provided, and a sleeve 16 passing therethrough is
Is inserted at the upper end. The upper end of the heat transfer tube 4 is shown in FIG.
Is attached to the upper tube sheet 2 by an attachment structure as shown in FIG.

At the time of this attachment, first, as shown in FIG. 3, a support tube 17 is fixed on the upper surface of the upper tube sheet 2 so as to surround the insertion hole 18 of the heat transfer tube 4. This support tube 17
Has a larger diameter than the heat transfer tube 4. The support tube 1
On the inner diameter surface of 7, a projection 19 is provided in advance by spot welding or the like. In this example, four projections 19 are provided.

As shown in FIGS. 4 and 5, the heat transfer tube 4 provided with a tapered enlarged portion 4a at the upper end is connected to the support tube 1.
7, and the upper end of the support tube 17 and the upper end of the heat transfer tube 4 are welded at the welded portion 20 as shown in FIG. At the time of this welding, if the end surface of the heat transfer tube 4 is inclined outward and a small space is left between the support tube 17 and the heat transfer tube 4, the penetration becomes sufficient and the welded portion 20 becomes strong. .

With this configuration, even if the welding portion 20 between the support tube 17 and the heat transfer tube 4 is separated, the enlarged diameter portion 4a of the heat transfer tube 4
Is caught by the projection 19, so that the heat transfer tube 4 does not fall and the upper tube sheet 2 is not damaged, so that repair can be performed only by welding the upper end of the support tube 17 and the upper end of the heat transfer tube 4 again.

Further, since the welding portion 20 is cooled by the cooling chamber 12 located below the upper tube sheet 2, corrosion of the welding portion 20 is prevented, and further, the welding portion 20 is interposed between the upper tube sheet 2 and the body 1. The bellows 10 reduces the force acting on the welded portion 20, thereby preventing the welded portion 20 from peeling off.

[0020]

As described above, according to the structure of the present invention, even if the welded portion between the support tube and the heat transfer tube is separated, the expanded portion of the heat transfer tube is caught by the projection, so that the heat transfer tube may fall. Instead, the upper end of the support tube and the upper end of the heat transfer tube can be repaired quickly only by welding again, and the operating rate of the cupola and the like is improved.

When a cooling chamber is provided below the upper tube sheet, the welded portion is cooled and its corrosion is suppressed. When a bellows is interposed between the body and the upper tube sheet, the difference in thermal expansion between the body and the heat transfer tube is obtained. Is absorbed and the burden on the weld is reduced, preventing peeling of the weld and reducing the need for repairs.
Work safety is improved, and great economic effects are obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a heat exchanger according to the present invention.

FIG. 2 is an enlarged vertical cross-sectional front view of the above.

FIG. 3 (a) is a top view of the support tube of the above, and (b) is a cross-sectional view showing a state of attachment to the upper tube plate of the above.

FIG. 4 is a sectional view showing a process of inserting the heat transfer tube according to the first embodiment;

FIG. 5 is a cross-sectional view showing an inserted state of the above heat transfer tube.

FIG. 6 is a cross-sectional view showing a welded state of the heat transfer tube.

FIG. 7 is a schematic diagram showing a preheating facility using a heat exchanger of a cupola;

FIG. 8 is a schematic sectional view of a conventional heat exchanger.

FIG. 9 is a sectional view showing a state in which the heat transfer tube is welded to an upper tube sheet.

FIG. 10 is a cross-sectional view showing a state where the heat transfer tube is inserted into a lower tube sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body 2 Upper tube sheet 3 Lower tube sheet 4 Heat transfer tube 4a Large diameter part 10 Bellows 12 Cooling room 17 Support tube 19 Projection 20 Welded part

Claims (5)

[Claims] 1. A heat exchanger in which a large number of heat transfer tubes 4 extending between an upper tube sheet 2 and a lower tube sheet 3 are accommodated inside a body 1, a support tube 17 having a diameter larger than that of the heat transfer tubes 4 is placed on top. The heat transfer tube 4 is fixed to the tube sheet 2, and the heat transfer tube 4 is inserted through the support tube 17.
7. A heat exchanger wherein the upper end of the heat transfer tube 7 and the upper end of the heat transfer tube 4 are welded at a welding portion 20. 2. The heat exchanger according to claim 1, wherein a tapered diameter portion is provided at an upper end of the heat transfer tube. 3. The heat exchanger according to claim 2, wherein a projection is provided on an inner diameter surface of the support pipe. 4. The heat exchanger according to claim 1, wherein a cooling chamber is provided below the upper tube sheet. 5. The heat exchanger according to claim 1, wherein a bellows 10 is interposed between the body 1 and the upper tube sheet 2.