DE19735630C2 - Heat exchanger and process for its manufacture - Google Patents

Description

The invention relates to a heat exchanger with a first container area for a me to be cooled or warmed in particular chemically aggressive dium, with a number of tubular ones in this first container region an enamelled metal of existing lines, the inner hollow clear a second container area for a second cooling and / or he form heating medium and which lines through openings of a pipe bottom out of the first container area and into one or more Guide chambers with the second, cooling or heating medium. The The invention also relates to a method for producing a heat rope shers.

Heat exchangers are needed for a variety of applications; there provide heat exchangers for chemically aggressive media, e.g. B. acids or Gases, a particularly demanding special case. It is about that a such medium is cooled, for example, during its reaction or storage or should also be heated, as effectively and quickly as possible. Heat exchangers are naturally suitable for this. Usually cooling and heat dissipation (or in certain applications in this case, also heating) medium, especially water, is thereby Pipes routed outside from the aggressive chemical medium are surrounded. The heat exchange takes place through the pipe wall instead of. These lines must be made of a highly resistant material or be protected in another way against the chemically aggressive medium. Contact between the media must be avoided as well as Diffusing the chemically aggressive medium out of the heat exchanger in unintended places. A particular problem area is the The pipes exit the volume range, i.e. the one specified above first container area in which the chemically aggressive medium is located.  

Known heat exchangers for this purpose exist, for example both the lines and the corresponding tube sheet through which the Line is led out of tantalum. Of course, this is particularly costly moderately very complex.

Alternatively, enamelled steel tubes are used, which are through a tube sheet are performed, the bushings with appropriate seals, at for example sealing rings are secured. On the one hand, this is complex and on the other hand also an incomplete protection, because these seals are in turn vulnerable and must be made from a material other than steel be made, usually made of plastic.

The post-published DE 196 10 501 A1 proposes accordingly through an enamelled tube sheet with cylindrical or conical holes To lead pipes made of enamelled steel and preferably by means of To seal round rings. As stated, such a ring would be the Be do not withstand demands. Would you be in a conception after the DE 196 10 501 A1 would omit the round rings, would be the ones proposed there Measures a seal is not guaranteed.

It would be extremely dangerous if the chemically aggressive media came through this Bushings could diffuse through in any form, since then could get into the other cooling or heating medium would get to the unprotected inside of the lines and there could cause significant damage. Besides, it can already be inside the area of the bushings or in the subsequent area corrosion of the chamber. This leads to significantly shortened periods Service life of the heat exchanger.

It is not possible, as may be obvious in other areas of technology, ver the steel pipes in the lead-through area with the tube sheet welding. These weld seams would in turn be aggressive  Exposed to medium and could not be re-enamelled or otherwise protected because there is no geometric accessibility.

In contrast, an object of the invention is to provide a heat exchanger propose an improved concept. Another is a Propose processes for its manufacture.

This first-mentioned task is in a generic heat exchanger solved in that the enamelled outer surfaces of the lines in the Openings in the tube sheet are leak-free and gas-tight thanks to a cryogenic Shrinkage generated press fit that passed the helium leak test inserted are.

In a process for its manufacture

• - Lines made by preparing short and straight sections be enamelled, these short, straight sections are over one or several connecting sections connected and welded and the Locally re-enamelled joints,
• - The lines or at least their short straight sections cryogenic hypothermic and with their short, straight sections into the openings of the tube sheet,
• - Then an expansion by heating and thereby a press The short straight sections in the openings that fit the Helium leak test passes.

With such a construction or method, the problem becomes Surprisingly solved: an implementation in which the enamelled coating are sitting directly on top of each other, are leak-proof and press-fit onto one another and the seal-free opening also meets all requirements. There are no longer any components that are exposed to the corrosive medium and this cannot penetrate either.  

Such a concept would previously have been considered impossible by all experts been; they never considered it either. This is particularly the case the complicated forms of the routing in these heat exchangers, which are curved and cannot be enamelled separately and also practical due to the geometrical conditions, no possibility in Press fit to be inserted at all. This also exists for the professional world Problem that enamel is not mechanically so precise can be edited that a liquid and gas tight connection ent stands.

Contrary to the prejudice of the professional world, however, this is according to the invention possible.

For this purpose, the press fit is generated by cryogenic shrinkage used. This has the particular advantage that a precise joining of the parts is possible that passes the standardized helium leak test.

It is particularly preferred if the tube sheet is also made of enamelled metal, this applies in particular to the inner surfaces of the public through which the cables pass.

Furthermore, it is particularly advantageous if an enamel layer of only 500 to 600 μm thick is used, which is only somewhat thicker in the area of the feedthrough, that is to say in the area of the press fit. The heat transfer coefficient k (W / m ² K) at the line pipes can be reduced by a very thin enamel layer, which naturally promotes the functionality of a heat exchanger very much.

Furthermore, it is particularly preferred if the lines each consist of a tube Section consist of the area inside and adjacent to the implementation through the opening forms as well as through other, separately manufactured Pipe sections. This can make it a relatively short one Pipe section for the actual implementation with high precision and with extreme  To manufacture precision also with regard to angular deviations to be avoided, which is of great advantage for an exact press fit.

It is particularly important to take into account that lines are in heat of the type of interest preferred here, two straight, parallel Ab have cuts through two openings in a common tube should pass through and the inside of the container in the area exactly opposite to the tube sheet with the openings by means of a 180 ° ge arcuate section are connected. It is for the implementation by the Pipe base therefore necessary, this entire element of the line exactly parallel to pass through the floor so that both outside of the cable in the Press-fit openings in cryogenic shrinkage are exactly parallel run, since even small canting could lead to problems.

According to the invention, the remaining straight sections can then be attached to the short straight sections longer part of the pipe welded on and the connection areas locally be enamelled again. These longer parts are less critical and must can only be manufactured with normal accuracy.

It will also be possible to standardize the manufacture of the heat exchangers. For namely, each heat exchanger lines of different lengths are turned on sets that do not interfere with each other geometrically; the curved connecting sections have different lengths that longer, straight sections can be endless, such as in described in DE 195 03 999 A1, made and in the required lengths be cut off and put together.

In the following, an embodiment of the invention is based on the drawing described in detail. Show it:

Figure 1 shows a section through a heat exchanger perpendicular to a Wan extension through which the lines pass.

Fig. 2 is a view, partially broken away, from the chamber on the tube sheet and

Fig. 3 is a schematic representation of an embodiment of a line.

A heat exchanger shown schematically in FIG. 1 has a cylindrical container 5 with an outer wall 7 and an inner first container region 10 . In the container area 10 there is an aggressive medium which is reacted or stored there and is to be cooled or, if appropriate, also heated. The medium can be a gas or a liquid; the actual reaction can also take place outside the container, so that the medium is only carried out for the purpose of heat exchange in the container ter 5 . The aggressive medium is through a nozzle 8 into the container area 10 - and leads out again through a second nozzle 9 .

In addition to the sockets 8 and 9 , in particular on a tube sheet 14 . This closes a side surface of the elongated cylindrical first container region 10 and is detachably connected to the other container walls. However, this connection is highly sealed and closed.

A multiplicity of openings 15 runs through the base 14 . The bottom 14 consists of an enamelled metal, possibly also from a relatively corrosion-resistant material such as Hastelloy.

A multiplicity of tubular lines 20 are located in the interior of the container region 10 . These lines 20 extend through the tube sheet 14 or the openings 15 therein and lead to a chamber 25 or 26 . This connection forms the second container area for a second medium, which is usually not aggressive and is often water or consists to a large extent of water. This second medium is used to remove or supply heat. The heat exchange between the two container areas is as intensive as possible, but there is no physical contact or even exchange.

The second medium is fed to the chamber 25 via a feed 27 . It flows from the chamber 25 into the lines 20 and through the openings 15 in the tube sheet 14 . Through the lines 20 , it passes through the long straight section (shown upwards in FIG. 1) into the bend at the top and again down into a further long straight section, again through openings 15 in the tube sheet 14 back into the second chamber 26 . The second medium then flows out of the chamber 26 via an outlet 28 .

The chambers 25 and 26 are separated by a partition 29 ; together, these two areas together form a two-chamber system. The content of the two areas 25 and 26 of the chambers differs by the temperature inherent in them. Since it is a heat exchanger as a whole, the second medium absorbs (or releases) temperature from the first medium in the container 5 as it flows through the line 20 , so that it is at a higher (or lower) in the chamber 26 ) Temperature arrives when she still had it in the exit area of chamber 25 .

The second medium can usually be used again and again, after it has cooled or again to the desired temperature doors is brought. Since it is usually ordinary water or a in any case deals with a substance that contains a lot of water, is dealing with the This medium is relatively uncritical.  

Fig. 2 shows a view seen from the chamber 25, 26 in the direction to the container wall fourteenth The supply 27 to the chamber 25 and the outlet 28 from the chamber 26 and the partition 29 between the two areas of the chamber are therefore clearly visible in section. In the section partially broken away on the right in FIG. 2, the openings 15 through which the lines 20 lead can be clearly seen. Of the lines 20 , basically only the inner region of the curvature at the upper end from FIG. 1 can be seen.

Also shown are the nozzles 8 and 9 which supply the first container region 10 with the first medium or discharge it therefrom.

The lines 20 are - as shown in FIGS. 1 and 2 in summary - each arranged in an arc above one another, so that the first container area 10 can be traversed by the largest possible number of such lines 20 and the function of the heat exchanger can be performed particularly effectively and with many wall contact areas can and thus a large heat exchange surface is achieved with minimal mass use, which results in high efficiency.

In Fig. 3 one of the lines 20 is shown in detail. The tube plate 14 through which the line 20 passes at a total of two points, namely through the openings 15, can again be seen at the bottom.

The line itself here consists of five sections in the exemplary embodiment shown, which makes the production particularly expedient. For example, two short, straight sections 31 and 32 are provided, which pass exactly through the openings 15 in the tube sheet 14 and are precisely parallel to one another. These short, straight sections 31 , 32 are each followed by a long, straight section 33 and 34, respectively. These long, straight sections are also essentially parallel to one another, this parallelism being less critical. These long sections can be produced and enamelled with a suitable process, in particular with an endless process according to DE 195 03 999 A1. The upper ends of the long, straight sections 33 , 34 are connected to one another by a connecting arch section 35 .

In the manufacture of the line 20 as a whole, the two long, straight sections 33 , 34 can be produced and enamelled and then connected to the Bo section 35 via two weld seams 38 . As a result, most of the entire line 20 is created . Now it is ensured in a precise alignment machine that the two short, straight, already enamelled sections 31 and 32 are welded to the then free two ends of the long, straight sections 33 , 34 so that they are exactly parallel to each other and each have an exact distance from each other. This in turn creates two weld seams 38 .

In another alternative, line 20 is made from a fully enamelled U-tube. When using complete U-tubes, the weld seams are completely eliminated.

At these junctures of the respective straight sections 31 and 33 or 32 and 34 there can therefore be a relatively slight kink, since the manufacturing tolerances of the long sections can be relatively large and only the precise parallelism of the two short end pieces is important.

Now in this phase, all four weld seams 38 between the five individual sections of the line 20 are re-enamelled. Now the fer term line 20 is inserted into the openings 15 of the tube sheet 14 . For this purpose, the line is cryogenically supercooled and thus easily fits into the prepared, for example enamelled, openings 15 of the tube sheet 14 . After heating the line 20 , an exact press fit is created, which passes the standardized helium leak test.

If complete U-tubes are used, the ends are machined directly.  

To understand the problem, it should be pointed out that only one line is shown in FIG. 3. In practice arise, as can be seen in FIGS . 1 and 2, here an enormous variety of closely adjacent openings in the tube sheet 14 , in each of which lines are mutually covering must be inserted. Enamelling at exactly this point during or after the insertion of the lines 20 is not possible.

Reference list

5

container

7

Wall of

5

8th

Support

9

Support

10th

first container area

14

Tube sheet

15

Openings in

14

20th

management

25th

chamber

26

chamber

27

Feed to

25th

28

Spout out

26

29

partition wall

31

short, straight section

32

short, straight section

33

long, straight section

34

long, straight section

35

connecting arch section

38

Welds

Claims (8)

1. Heat exchanger with a first container region ( 10 ) for a medium to be cooled or heated, in particular chemically aggressive medium, wherein in this first container region ( 10 ) a number of tubular lines made of an enamelled metal ( 20 ) run, the inner cavities of a second Form container area for a second, cooling and / or heating medium and which lines ( 20 ) through openings ( 15 ) in a tube sheet ( 14 ) out of the first container area ( 10 ) and into one or more chambers ( 25 , 26 ) with the lead second, cooling or heating medium, characterized in that the enamelled outer surfaces of the lines ( 20 ) in the openings ( 15 ) in the tube sheet ( 14 ) leak-free and gas-tight by a cryogenic shrink fit, which passes the helium leak test, are inserted . 2. Heat exchanger according to claim 1, characterized in that the enamel layer on the lines ( 20 ) has a thickness of 500 to 600 microns outside the area in or adjacent to the openings ( 15 ). 3. Heat exchanger according to one of the preceding claims, characterized in that each of the lines ( 20 ) through one of the openings ( 15 ) in the first loading container area ( 10 ) and through one of the other openings ( 15 ) in the same tube sheet ( 14 ) out of the container area ( 10 ). 4. Heat exchanger according to claim 3, characterized in that each of the lines ( 20 ) from at least two parallel, not bent pipe sections ( 31 , 32 , 33 , 34 ) and a third bend of 180 ° and the parallel pipe sections connecting arc section ( 35 ) exists. 5. Heat exchanger according to one of the preceding claims, characterized in that the lines ( 20 ) cut at least a relatively short, straight Rohrab ( 31 ) in the region of the passage through the openings ( 15 ) of the tube bottom ( 14 ) and one short of these Pipe section ( 31 ) adjoining further pipe section ( 33 ) connected to this pipe section by welding, the connection region subsequently being locally enamelled again. 6. Heat exchanger according to claim 4 and 5, characterized in that the lines ( 20 ) each have two relatively short, straight Rohrab sections ( 31 , 32 ) in the implementation through two openings ( 15 ) of the tube sheet ( 14 ) and each subsequent , with the short, straight pipe sections ( 31 , 32 ) connected by welding long, straight pipe sections ( 33 , 34 ), and a fifth, a bend of 180 ° and the long straight pipe sections ( 33 , 34 ) connect the arc section ( 35 ), the four connecting areas then being locally enamelled again. 7. Heat exchanger according to one of the preceding claims, characterized in that the tube sheet ( 14 ) consists of enamelled metal, in particular in the inner surfaces of the openings ( 15 ). 8. A method for producing a heat exchanger according to one of the preceding claims, in which
Lines (20) are produced by short, straight sections (31, 32) are prepared and enamelled, welded, these short, straight sections (31, 32) connected via one or more connecting portions (33, 34, 35) and and the joints be re-enamelled locally,
the lines ( 20 ) or at least their short straight sections ( 31 , 32 ) are cryogenically supercooled and inserted with their short, straight sections ( 31 , 32 ) into the openings ( 15 ) of the tube sheet ( 14 ),
then expansion by heating and thereby a press fit of the short straight sections ( 31 , 32 ) in the openings ( 15 ), which passes the helium leak test.