JP3502005B2 - Heat exchanger - Google Patents

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 into a cupola.

[0002]

2. Description of the Related Art Conventionally, in a cupola C for melting a cast material as shown in FIG. 7, the combustion gas discharged from the cupola C is further heated in a combustion chamber F as shown by a solid line in the figure. The heat exchangers H ₁ and H ₂ sequentially,
In addition to exhausting it to the atmosphere by the blower B ₁ , the low temperature air introduced by the blower B ₂ is sequentially passed through the heat exchangers H ₂ and H ₁ to be preheated by the combustion gas as shown by the broken line in the figure,
Equipment used to send to Cupola C is used.

The heat exchanger H ₁ is, as shown in FIG.
Inside the body 50, a large number of heat transfer tubes 53 extending over the upper tube sheet 51 and the lower tube sheet 52 are accommodated, and high-temperature combustion gas passes from the gas supply chamber 54 above the upper tube sheet 51 through the heat transfer tubes 53. It flows into the gas discharge chamber 55 below the lower tube sheet 52,
A structure in which the low-temperature air flowing in from the lower blast inlet 56 is meandered by the baffle 57, absorbs heat from the combustion gas through the tube wall of the heat transfer tube 53, and is blown out from the upper blast outlet 58 of the body 50. Has become.

As shown in FIG. 9, the upper end portion 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 welded portion 59. Further, 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 by a packing 60.

[0005]

The welded portion 59 is easily corroded by the action of high-temperature combustion gas, and when this corrosion progresses, the welded portion 59 may separate and the heat transfer tube 53 may drop. In such a case, repair is very difficult with the structure in which the heat transfer tube 53 is directly welded to the upper tube sheet 51.

Therefore, the present invention is to provide a heat exchanger in a multi-tube heat exchanger in which the welded portion of the heat transfer tube is less likely to peel off and can be easily repaired even if it is peeled off.

[0007]

In order to solve the above problems, the present invention relates to a heat exchanger in which a plurality of heat transfer tubes extending over an upper tube plate and a lower tube plate are housed inside a body. A support tube with a diameter larger than that of the heat tube and a protrusion on the inner diameter surface is fixed to the upper tube sheet, and a heat transfer tube whose upper end is expanded in diameter is inserted through this support tube, and the upper end of the support tube and the upper end of the heat transfer tube are inserted. Welded.

According to this structure, even if the welded portion of the support tube and the heat transfer tube separates, the enlarged diameter portion of the heat transfer tube is caught by the protrusion, so that the heat transfer tube does not drop and the upper end portion of the support tube is not dropped. It can be repaired by simply welding the upper end of the heat transfer tube again.

If a cooling chamber is provided below the upper tube sheet, the welded part is cooled and corrosion thereof is suppressed. If 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 caused. Is absorbed, the load on the welded portion is reduced, and peeling of the welded portion is prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in this heat exchanger H, a large number of heat transfer tubes 4 extending over an upper tube sheet 2 and a lower tube sheet 3 are housed inside a body 1. 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 in the lower portion of the body 1 and a blower outlet 9 is provided in the upper portion. The low-temperature air flowing in from the blower inlet 8 meanders by the baffle plate 5 and the heat transfer tube 4
The heat is absorbed from the combustion gas via the tube wall of and is sent out from the air outlet 9.

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

Below the upper tube sheet 2, a cooling chamber 12 defined by a partition wall 12a is provided, and cold air is supplied to the cooling chamber 12 from a cold air supply pipe 13. The tip portion of the cold air supply pipe 13 is slidably inserted into the short pipe 14 attached to the upper tube sheet 2 to absorb the vertical movement of the upper tube sheet 2.

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

In this attachment, first, as shown in FIG. 3, the support tube 17 is fixed to 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
A protrusion 19 is previously provided on the inner diameter surface of 7 by spot welding or the like. In this example, the protrusions 19 are provided at four places.

As shown in FIGS. 4 and 5, the support tube 1 is provided with the heat transfer tube 4 having a tapered expanded portion 4a at the upper end thereof.
7, 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 tilted outward and a minute gap is left between the support tube 17 and the heat transfer tube 4, the penetration is sufficient and the welded part 20 becomes strong. .

With this structure, even if the welded portion 20 between the support tube 17 and the heat transfer tube 4 is separated, the expanded diameter portion 4a of the heat transfer tube 4 is formed.
Since the heat transfer tube 4 does not drop and the upper tube sheet 2 is not damaged, the repair can be performed only by re-welding the upper end portion of the support tube 17 and the upper end portion of the heat transfer tube 4.

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

[0020]

As described above, according to the structure of the present invention, even if the welded portion of 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 cannot fall. Instead, the upper end of the support pipe and the upper end of the heat transfer pipe can be repaired quickly by simply re-welding, and the operating rate of the cupola and the like is improved.

If a cooling chamber is provided below the upper tube sheet, the welded part is cooled and its corrosion is suppressed. If 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 caused. Is absorbed and the burden on the welded part is reduced, so peeling off of the welded part is prevented and the need for repair is reduced,
The work safety is improved and a great economic effect is obtained.

[Brief description of drawings]

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

FIG. 2 is an enlarged front view of the upper part of the above.

FIG. 3 (a) is a top view of the same support tube as above. (B) Sectional drawing which shows the attachment state to the upper tube sheet same as the above.

FIG. 4 is a sectional view showing a process of inserting the heat transfer tube of the above.

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

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

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

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

FIG. 9 is a sectional view showing a welding state of the heat transfer tube to the upper tube sheet of the above.

FIG. 10 is a cross-sectional view showing a state in which the heat transfer tube of the above is inserted into a lower tube sheet.

[Explanation of symbols]

1 torso 2 Upper tube sheet 3 Lower tube sheet 4 heat transfer tubes 4a Expanding part 10 Bellows 12 Cooling chamber 17 Support tube 19 protrusions 20 Weld

Claims (2)

(57) [Claims] 1. An upper tube sheet 2 and a lower tube sheet 3 inside a body 1.
In many present heat exchanger containing a heat exchanger tube 4 over bets, the heat transfer tube 4 than diameter of the support tube 17 is fixed to the upper tube plate 2, by inserting the heat transfer tubes 4 to the support tube 17, Den Heat tube 4
1. A heat exchanger characterized in that a tapered expanded portion 4a is provided at the upper end of the heat exchanger, and the upper end of the support pipe 17 and the upper end of the heat transfer pipe 4 are welded at the welded portion 20. 2. The heat exchanger according to claim 1 , wherein a projection 19 is provided on an inner diameter surface of the support tube 17.