DE8121511U1 - Heat exchanger. - Google Patents

Abstract

1. Heat exchanger, more especially for utilising exhaust gas heat, comprising a group of heattransfer tubes (8), which are arranged in a tubular casing (4) and are provided with baffle plates (6), the said tubes being respectively fixed on the input side and the output side in a tube base (10, 11), and with a protective tube base (13) arranged on the inlet side of the heat exchanger at a small distance before the tube base on the entry side, before which base (13) is provided an entry chamber (20) and in which are arranged short tubes (14) projecting partially into the heat transfer tubes (8), characterised in that the short tubes (14) project beyond the tube base (10) into the heat transfer tubes (8) and that the space between the tube base (10) and the protective tube base (12) is sealed off outwardly at the periphery with a packing (18) arranged between the tube base (10) and the protective tube base (12).

Description

The invention relates to a heat exchanger, in particular for exhaust gas heat utilization according to the preamble of the claim 1 .

The heat recovery from exhaust gases from diesel engines or the like. Is required more and more and is increasing Meaning; shell-and-tube heat exchangers made of steel or high-alloy steel are preferably used for this purpose. The exhaust gas is usually passed through the heat transfer pipes because it is possible to clean it this is better given while the water to be heated is led around the pipes.

In the tube sheet of the heat exchanger at the gas inlet, however, it occurs primarily in the area between the heat transfer tubes to a build-up of heat while the side of the tube sheet facing the water is cooled. It exists the risk that over time the material will become fatigued and cracks will appear in the tube sheet, which in turn will lead to leaks leads.

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The object of the present invention is therefore to provide the heat exchanger of the type mentioned at the beginning Art to be trained in such a way that material fatigue cannot occur even after a long period of use and the danger of cracks and leaks is avoided.

This object is achieved by the design specified in the characterizing part of claim 1.

The inventive training is so to speak a heat shield created, which protects the actual tube sheet of the heat transfer tubes against high temperatures shields and thus ensures that between the two sides of the tube sheet a practically negligible Temperature gradient occurs; as a result, the material of the tube sheet can no longer tire, not even after a long time Use time, and the risk of cracks and leaks is avoided.

Advantageous and expedient developments of the invention Solution are characterized in the subclaims.

In order to keep the overall length and heat losses as low as possible, the development according to claim 2 is provided.

The further embodiment according to claim 3 increases the heat protection effect.

The further embodiment according to claim 4 also reduces the heat transfer to the tube sheet of the heat transfer tubes; this is also the case through the further

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Design of the problem solution according to the invention according to Claim 5.

Since the heat-emitting medium, for example the hot exhaust gases, only remains on the outlet side of the heat exchanger has a very low temperature, the second tube sheet, as indicated in claim 6, only needs to be provided on the inlet side.

One for the use of the heat exchanger according to the invention advantageous design is specified in claim 7.

The invention will now be explained in more detail with reference to an embodiment shown in the accompanying drawing will.

The drawing shows one side of a heat exchanger 2, which has a jacket tube 4 in which a baffle plate provided tube bundle of heat transfer tubes 8 is arranged. The heat transfer tubes 8 sit on both sides in the tube sheet firmly connected to the jacket tube 4, of which only one tube sheet 1o is shown. In front of the tube sheet a second tube sheet 12 is arranged at a small distance, in which a tube bundle of relatively short tubes 14 is arranged. The tubes 14 partially protrude into the heat transfer tubes 8 into it, preferably to just above the tube sheet 1o.

The outside diameter of the tubes 14 can be smaller than the inside diameter of the heat transfer tubes 8,

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so that in the installed position, the tubes 14 and the heat transfer tubes 8 do not touch.

The one formed between the two tube sheets 1o and 12 Intermediate space 16 is sealed off from the outside with the aid of an annular seal 18 ″. Intermediate space 16 itself can additionally filled with asbestos.

In front of the tube sheet 12, an inlet chamber 2o is sealed (Seal 21) arranged. On the other side, not shown, of the heat exchanger 2 open out Heat exchanger tubes 8 directly into an outlet chamber.

The jacket tube 4 has an inlet connection 22 and an outlet connection (not shown).

The heat exchanger 2 shown is designed in particular for recovering heat from exhaust gases. The approximately Exhaust gases at 55o - 600C are fed into the inlet chamber and flow from there through pipes 14 and 8 to the outlet chamber. They give their heat through the heat transfer pipes to the heat transfer pipes water flowing around it, which flows into the jacket space 24 of the jacket tube 4 via the inlet connection 22.

The outer tube sheet 12 acts as a heat shield for the tube sheet 1o of the heat transfer tubes 8. The to the jacket space 24 cool tube sheet 1o can arise the outside 26 no longer heat up so much that too great a temperature gradient, too great thermal stresses as well as material fatigue and the resulting cracks.

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The heat is absorbed by the tube sheet 12 and thus shielded from the tube sheet 12 with respect to the tube sheet 1o. Since the inside 28 of the tube sheet 12 is not cooled, there can be no large temperature differences between the two Sides of the tube sheet 12 occur, so that thermal stresses do not arise. But also material fatigue that occurs over time as a result of the high exhaust gas temperatures and any cracks in the outer tube sheet 12 caused thereby are harmless because the shielding effect is not affected by this.

Claims (7)

1 objections 1. Heat exchanger, in particular for exhaust gas heat utilization, with a bundle of heat transfer tubes arranged in a jacket tube and provided with heat conduction plates, which are arranged on both sides in a tube sheet, characterized in that at a distance in front of the tube sheet (1o) of the heat transfer tubes (8) further tube sheet (12) is arranged, in which short tubes (.14) of a second tube bundle are arranged, which partially protrude into the heat transfer tubes (8). 2. Heat exchanger according to claim 1, characterized in that the second tube sheet (12) is arranged at a small distance from the tube sheet (1o) of the heat transfer tubes (8). 3. Heat exchanger according to claim 1 or 2, characterized in that the intermediate space (16) between the Dr.K./H. -2- ■ · »·? 1 I t I I C lilt } II ItI * til) if I lilt} 111 I t ι)]) i ItIIIl)) ι > j ι) ι -2- both tube sheets (Ιο, 12) sealed to the outside (sealing 'ι tung 18) and with a heat-insulating and heat-resistant ^ί; Stenten material, such as asbestos, is filled. 4. Heat exchanger according to claim 1, characterized in that the tubes (14) protrude beyond the tube sheet (1o) into the heat transfer tubes (8). 5. Heat exchanger according to claim 1 or 4, characterized in that the outer diameter of the tubes (14) is smaller than the inner diameter of the heat transfer tubes (8) and that the tubes (14) are arranged approximately concentrically within the heat transfer tubes (8). 6. Heat exchanger according to one of the preceding claims, characterized in that the second tube sheet (12) is provided only on the inlet side of the heat exchanger (2) for the heat-emitting medium. 7. Heat exchanger according to one of the preceding claims, characterized in that an inlet chamber (2o) for hot exhaust gases is connected to the second tube sheet (12) and thus to the tubes (14), that the shell space (24) surrounding the heat transfer tubes (8) ) the water to be heated flows through an inlet and outlet connection If tilt -3- and that an exhaust gas outlet chamber is connected to the tube sheet of the heat transfer tubes (8) on the outlet side is. -4-