EP0947794A1 - Method for producing finned tubes - Google Patents

Abstract

The tube (R), at least on a part of its surface, is provided with at least one row of tongue-type ribs (F) produced by inclined incisions into the tube material and erection of the thus-produced tongues. The heat transmitter can be used as an air-cooled condenser with ribbed tubes in a power plant with at least one steam producer for operation of at least one turbine driving an electrical generator.

Description

The invention relates to a method for producing at least one Part of its surface with ribs enlarging the heat transfer surface provided pipes, especially for heat exchangers, the pipes being one have a flat cross-section with a small height in relation to the width.

DE 43 22 405 C2 are for use in heat exchangers certain pipes and a method for their production is known in which the pipes and those attached to at least part of their surface Ribs are made of steel and joined together by a capacitor discharge welding process be welded. Because of the high This known method is not a heat load during welding applicable when the pipes and / or fins with a Corrosion protection layer are provided, as this is at least locally destroyed and thus becomes ineffective.

In order to be able to manufacture corrosion-resistant heat transfer elements, EP 0 417 894 A2 proposes a manufacturing process in the aluminum-coated steel tubes with aluminum fins together by being soldered in that they are used for a certain period of time Temperature increase are exposed, which is at least partially Melting and thus causing the aluminum layers to run into one another, without creating an iron-aluminum bond. Since the Boundary conditions of the soldering method known from EP 0 417 894 A2 Achieving a firm connection between the fin and tube very precisely this known method is very complex and not suitable for an economical large-scale application.

In order to avoid the disadvantages of these known methods, according to the EP 0 822 025 A1, EP 0 822 026 A1 and EP 0 823 296 A2 further processes for the production of corrosion-resistant heat exchangers and associated finned tubes have been developed. These procedures have become proven in practice.

The invention has for its object to provide a method for producing finned tubes of the type defined, which on the one hand enables cheaper manufacture of such tubes and on the other hand creates finned tubes with improved heat transfer. Such finned tubes are to be used in particular for air-cooled condensers with a direct or indirect cooling system.

The solution to this problem by the invention is characterized in that a band made of light metal is provided at least on part of one of its surfaces with at least one row of tongue-like ribs running in the longitudinal direction of the band, by making cuts corresponding to the width of the ribs at a distance corresponding to the rib division and with a length corresponding to the height of the ribs is introduced at an acute angle to the surface into the material of the band and the tongues thus formed between adjacent incisions are erected at least with their free end approximately at right angles to the band surface, and that the band provided in this way with ribs is transverse to its longitudinal direction is deformed into a tube with a flat cross section and is welded to one another by at least one longitudinal seam at its edges.

With the method according to the invention are made of light metal existing, flat band one or more rows of tongue-shaped Ribs made. This one-piece ribbed band is turned across its longitudinal direction to a tube with a flat cross section and in proportion deformed to the width of low height, the longitudinal edges of the band be welded together by a longitudinal seam to close the pipe form. The manufacture of the tongue-shaped ribs directly from the The material of the tape has a high thermal conductivity between the ribs and Pipe wall result. The tongue-shaped ribs result in a high Turbulence, so that overall a pipe with reduced manufacturing costs improved heat transfer is created, which is particularly for air-cooled condensers, regardless of whether they are in one direct or in an indirect cooling system.

In addition to the possibility of a pipe according to the invention in one piece from a To produce a correspondingly wide band can, according to another characteristic According to the invention, each tube can also be made from two tapes before or deformed into a half-shell after each generation of the ribs and then together at their two longitudinal edges to form a tube be welded.

The invention further proposes to produce several Rows of ribs cover the surface of the band in the longitudinal direction of the band to divide extending grooves that in one of the respective width of the Corresponding ribs run parallel to each other. This is it easily possible using any number of rows of ribs Form selectable rib widths on the pipe surface, whereby by A larger number of rows of fins increases the turbulence of the pipes. According to the invention, the grooves can be at different intervals run to each other so that rows of ribs with different widths Ribs result. The depth of the grooves is according to the Wall thickness of the strip minus the respective tube wall thickness selected.

To either deform the ribbed band into one To facilitate pipe or to a pipe half-shell, according to the tape another feature in the area of its rib-free surface only the wall thickness corresponding to the respective tube wall thickness, so that the tape can be deformed in a simpler manner transverse to its longitudinal direction can.

If the tubes according to the invention are used in heat exchangers come, whose medium flowing inside the pipes is a steel one Lining the pipes may appear desirable or necessary According to a further feature of the invention, the light metal strip before Production of the ribs connected with a steel carrier tape. The light metal strip is preferably used as a support on the steel one Carrier tape rolled on. The subsequent process steps, namely the Production of the ribs and the deformation of the band into a tube or a pipe half shell remain unchanged.

To those with a flat cross section with less in relation to the width Height trained pipes against larger pressure differences To protect deformations, the invention further proposes between the opposite flat sides of the tube support means to provide. There are various ways of training these proppants Possibilities according to the invention.

In a first embodiment of the invention, the support means are through arranged on the inside of at least one of the flat sides of the tube Pins or the like are formed. In a second embodiment the support means through a in the longitudinal direction of the tube between the Flat corrugated tape with the height of the pipe cross-section corresponding wave height.

Furthermore, the invention proposes that the support means Forms of the band to form before it is deformed into a tube or a half-shell with either half or the whole Height of the later pipe cross section corresponding extension become. Especially in the case of a light metal alloy These characteristics can be easily introduced into tape, whereby according to the invention the band in the area of the later manifestations with the Provide cross-section of these characteristics corresponding recesses is in the area of the wall thickness of the band up to about Pipe wall thickness is reduced.

In a preferred embodiment of the invention, the Expressions have a rotationally symmetrical shape and are frustoconical with half the height of the pipe cross-section appropriate height trained.

To prevent undesirable deformation of the finned tube not only in one To avoid negative pressure in the tube, but also in the event of overpressure in the tube, can the support means with each other or with both flat sides of the Finned tube connected, preferably welded. This will be a Inflation of the flat tube prevented. Finally, it is possible that Form support means in the longitudinal direction of the tube continuously, so that the Interior of the tube is divided into several channels.

The invention also relates to a finned tube with at least part of it Surface arranged, increasing the heat transfer area Ribs and with a flat tube cross-section in relation to the width low height. The design of this finned tube is according to the invention characterized in that the tube made of light metal at least on part of its surface with at least one row of tongue-like, through oblique incisions in the pipe material and erecting it resulting ribs produced is provided.

Furthermore, the invention relates to a particularly for use as air-cooled condenser certain heat exchangers with finned tubes that produced according to the inventive method or according to the invention are trained.

Finally, the invention relates to a power plant with at least one Steam generator for operating at least one turbine, which is a generator for Generation of electrical energy drives, as well as with at least one Heat exchanger, preferably condenser, with finned tubes is equipped, which is produced according to the inventive method or are designed according to the invention.

Fig. 1

einen Querschnitt durch ein erstes Ausführungsbeispiel eines Rippenrohres,

Fig. 2

eine perspektivische Ansicht eines Teils eines Leichtmetallbandes, aus dem das Rohr nach Fig. 1 hergestellt wird,

Fig. 3

einen Querschnitt durch das Band gemäß Fig. 2 nach dessen Verformung zur Rohrhalbschale und Ausformung von Ausprägungen,

Fig. 4

einen Längsschnitt gemäß der Schnittlinie IV-IV in Fig. 2 nach Ausbildung der zungenförmigen Rippen,

Fig. 5

einen der Fig. 1 entsprechenden Querschnitt durch ein zweites Ausführungsbeispiel eines mit einem stählernen Kern versehenen Rippenrohres,

Fig. 6

eine der Fig. 2 entsprechende perspektivische Darstellung des mit einer Auflage aus einem Leichtmetallband versehenen stählernen Trägerbandes vor Beginn der Verformungen,

Fig. 7

einen der Fig. 3 entsprechenden Querschnitt des zu einer Halbschale verformten Bandes nach Fig. 6,

Fig. 8

einen den Fig. 1 und 5 entsprechenden Querschnitt durch eine dritte Ausführungsform,

Fig. 9

einen weiteren Querschnitt durch eine vierte Ausführungsform des Rippenbandes,

Fig. 9a

eine Seitenansicht einer ersten Ausführungsform des beim Rippenrohr nach Fig. 9 als Stützmittel verwendeten Wellbandes und

Fig. 9b

eine alternative Ausführungsform des Wellbandes gemäß Fig. 9a.

Several exemplary embodiments of a finned tube according to the invention are shown in the drawing, namely:

Fig. 1

3 shows a cross section through a first exemplary embodiment of a finned tube,

Fig. 2

2 shows a perspective view of part of a light metal strip from which the tube according to FIG. 1 is produced,

Fig. 3

3 shows a cross section through the band according to FIG. 2 after it has been deformed into a pipe half-shell and shaped,

Fig. 4

2 shows a longitudinal section along the section line IV-IV in FIG. 2 after the tongue-shaped ribs have been formed,

Fig. 5

1 shows a cross section corresponding to FIG. 1 through a second exemplary embodiment of a finned tube provided with a steel core,

Fig. 6

2 shows a perspective view corresponding to FIG. 2 of the steel carrier strip provided with a support made of a light metal strip before the deformations begin,

Fig. 7

3 shows a cross section corresponding to FIG. 3 of the band deformed into a half-shell according to FIG. 6,

Fig. 8

1 and 5 corresponding cross section through a third embodiment,

Fig. 9

another cross section through a fourth embodiment of the ribbed belt,

Fig. 9a

a side view of a first embodiment of the corrugated tape used as a support means in the finned tube according to FIG. 9 and

Fig. 9b

an alternative embodiment of the corrugated tape according to FIG. 9a.

The first embodiment shown in FIGS. 1 to 4 shows a Finned tube R, which has a continuous flat cross section in relation to the width of the finned tube R has a small height, such as in particular the cross-sectional view in Fig. 1 emerges. On his each other opposite flat sides is the finned tube R with several rows tongue-like ribs F, which are shown in Fig. 1 in the front view and in Fig. 4 are shown in side view. To prevent deformation of the finned tube R to avoid due to large pressure differences are between each other opposite flat sides of the tube R provided support means that in the first embodiment as frustoconical forms A are executed.

1 to 4 made of light metal, preferably aluminum, is produced using a band B, part of which is shown in perspective in FIG. 2. In the exemplary embodiment, this flat band B made of light metal has edge regions B ₁ which have a wall thickness which corresponds to the thickness of the tube wall. In the area between the edge areas B ₁ , the band B has a plurality of strip-shaped areas B ₂ with a greater wall thickness, which are separated from one another by a groove N. The depth of these grooves N corresponds to the greater wall thickness of the strip B minus the respective wall thickness of the later finned tube R.

In the strip-shaped areas B _{2 of} the band B, rows of tongue-like ribs F are produced in the longitudinal direction of the band by making incisions E corresponding to the respective width of the ribs F at a distance corresponding to the rib division and with a length corresponding to the rib height at an acute angle to the surface into the material of the band B can be introduced, as shown in FIG. 4. The resulting tongue-shaped ribs F are then erected in such a way that, at least with their free end, they run approximately at right angles to the belt surface, as is shown in FIG. 4. This results in the strip-shaped areas B _{2 of} the tape B in one piece with the ribs F made of tape material, in a number of rows which corresponds to the number of the strip-shaped areas B _{2 of} the tape B. While the ribs F in FIG. 4 are shown in the side view, these ribs F which are arranged in a number of adjacent rows can be seen in the front view in FIG. 1.

In the first embodiment shown in FIGS. 1 to 4, the fins F are produced after the band B in its edge regions B _{1 has} previously been semicircularly deformed transversely to its longitudinal direction, so that there is a half-shell for the finned tube R later, such as Fig. 3 reveals. After the formation of this half-shell, the ribs F are produced in the manner described above. Of course, the ribs F can also be produced in the flat band B according to FIG. 2 and the edge regions B _{1 can} only be deformed into the half-shell thereafter.

In order to avoid deformations of the finned tube R having a very flat tube cross section due to high pressure differences, support means in the form of frustoconical shapes A are provided in the first embodiment according to FIGS. To prepare these versions A, the band B according to FIG. 2 is provided with circular recesses C, which are produced, for example, by milling. In the area of these circular recesses C, the wall thickness of the band B in the areas B _{2 is} reduced to approximately the wall thickness of the finned tube R to be. Then, by embossing these recesses C, the frustoconical shapes A according to FIG. 3 are created. In the exemplary embodiment, the height of these frustoconical shapes A corresponds to half the height of the later tube cross section, so that mutually opposite and interacting shapes A according to FIG. 1 form a reliable support for the opposite flat sides of the finned tube R. 1 further shows that the two pipe half-shells according to FIG. 3 are welded together at their edges by two longitudinal seams S to form the pipe.

8 shows a further embodiment of one of two half shells According to the above explanations, the finned tube R, the differs from the first embodiment in that as Proppant pins D are arranged. In the exemplary embodiment, these are Pins D with one of the entire height of the later finned tube cross-section appropriate length only attached to one of the two half shells, and by welding. The pins D arranged in two longitudinal rows can lie next to each other or be offset from one another.

The further exemplary embodiment according to FIGS. 9, 9a and 9b again shows a finned tube R consisting entirely of light metal, in which a corrugated strip W running between the flat sides of the tube R is arranged as a support means. This corrugated band W has a corrugation height corresponding to the height of the pipe cross section. The waves W _{1 of} the wave band W can be sinusoidal according to FIG. 9a or rectangular according to FIG. 9b, as is characterized by W ₂ .

The further exemplary embodiment according to FIGS. 5 to 7 shows the possibility of to provide the finned tube R with a steel core.

For this purpose, as shown in FIG. 6, the strip B made of light metal is provided with a carrier strip T made of steel by rolling the light metal strip onto the steel carrier strip T as a support. The band B made of light metal is in turn divided by grooves N into a plurality of strip-shaped regions B ₂ , in which the tongue-shaped ribs F are then produced as shown in FIG. 4. In contrast to the first exemplary embodiment according to FIGS. 1 to 4, the edge regions T _{1 of} the carrier tape T form the semicircular areas of the half-shells according to FIG. 7 deformed transversely to the longitudinal direction of the tape.

In this embodiment too, support means in the form of Characteristics A are formed, but in this case in the carrier tape T be carried out. In the area of this later version A this is over Light metal existing tape rolled onto the carrier tape T. B again provided with circular recesses C, such as in particular Fig. 6 reveals.

Fig. 5 shows that this with a steel core finned tube R with regard to the formation and arrangement of the ribs F the other Executions corresponds. The tongue-shaped ribs F are also here arranged several adjacent rows, the width of the Ribs F can be different.

Of course, it is possible to manufacture the finned tube R not from two bands B or carrier bands T with the aid of two half-shells, but exclusively from a band B or T with double width. In this case, the band B or carrier band T has a rib-free region in the middle with a width twice the edge regions B ₁ and T ₁ . In this rib-free area, the tape B or carrier tape T is bent semicircularly, so that only one longitudinal seam S has to be produced to produce the finished tube, which connects the free edges of the tape B or T to one another to form the tube. In such a production, it is expedient to produce the ribs F in the flat band B, ie before the band B or T is deformed into a tube.

Reference list

A

Expression

B

tape

B ₁

Edge area

B ₂

strip-shaped area

C.

Recess

D

pen

E

incision

F

rib

N

Groove

R

Finned tube

S

Longitudinal seam

T

Carrier tape

T ₁

Edge area

W

Corrugated tape

W ₁

Sine wave

W ₂

Square wave

Claims (20)

Process for the production of tubes (R) provided at least on part of their surface with fins (F) enlarging the heat transfer surface, in particular for heat exchangers, the tubes (R) having a flat cross section with a small height in relation to the width,
characterized,
that a band made of light metal (B) is provided at least on part of one of its surfaces with at least one row of tongue-like ribs (F) running in the longitudinal direction of the band, by making cuts (E) corresponding to the width of the ribs at a distance corresponding to the pitch of the ribs and with one of the Rib height corresponding length introduced at an acute angle to the surface into the material of the band (B) and the tongues thus formed between adjacent incisions (E) are at least raised with their free end approximately at right angles to the band surface, and that in this way this is integrally formed with ribs (F ) provided band (B) is then deformed transversely to its longitudinal direction into a tube (R) with a flat cross section and is welded to one another at its edges by at least one longitudinal seam (S). Method according to Claim 1, characterized in that each tube (R) is made from two strips (B) before or after production the ribs (F) each deformed into a half-shell and then on their two longitudinal edges welded together to form a tube (R) become. A method according to claim 1 or 2, characterized in that for Production of several rows of ribs through the surface of the band (B) in the longitudinal direction of the grooves (N) is divided into one distance corresponding to the respective width of the ribs (F) parallel to each other. A method according to claim 3, characterized in that the grooves (N) run at different distances from each other. A method according to claim 3 or 4, characterized in that the Depth of the grooves (N) the wall thickness of the band (B) minus the corresponds to the respective pipe wall thickness. Method according to one of claims 1 to 5, characterized in that that the band (B) in the area of its rib-free surface only a has the corresponding wall thickness of the respective tube wall thickness. Method according to one of claims 1 to 6, characterized in that that the light metal strip (B) with before the production of the ribs (F) a carrier tape (T) made of steel. A method according to claim 7, characterized in that the Light metal band (B) as a support on the steel carrier band (T) is rolled on. Method according to at least one of claims 1 to 8, characterized characterized in that between the opposite Flat sides of the tube (R) proppant are provided. A method according to claim 9, characterized in that the support means by at least one of the flat sides of the tube (R) on the inside Arranged pins (D) or the like are formed. A method according to claim 9, characterized in that the support means by a in the longitudinal direction of the tube (R) between its flat sides running corrugated tape (W) with the height of the pipe cross-section appropriate wave height are formed. A method according to claim 9, characterized in that the support means are formed by expressions (A) of the tape (B, T), which before its forming into a tube (R) or into a half-shell with a either half or the full amount of the later Pipe cross section corresponding extension can be produced. A method according to claim 12, characterized in that the band (B) in the area of the later versions (A) with the cross section of these Characteristics (A) corresponding recesses (C) is provided in whose area is the wall thickness of the band (B) up to about Pipe wall thickness is reduced. A method according to claim 12 or 13, characterized in that the Characteristics (A) have a rotationally symmetrical shape. A method according to claim 14, characterized in that the Characteristics (A) frustoconical with half the height of the Pipe cross section corresponding height are formed. Method according to one of claims 9 to 15, characterized in that that the support means with each other or with both flat sides of the Finned tube (R) are connected. A method according to claim 9 or 16, characterized in that the Support means formed continuously in the longitudinal direction of the tube (R) and thus the inside of the finned tube (R) into several channels divide. Finned tube with fins (F) arranged on at least part of its surface and increasing the heat transfer area and with a flat tube cross-section with a small height in relation to the width,
characterized,
that the tube (R) made of light metal is provided on at least a part of its surface with at least one row of tongue-like ribs (F) produced by oblique incisions (E) in the tube material and erecting the resulting tongues. Heat exchanger, in particular for use as an air-cooled Condenser, with finned tubes, according to the procedure at least one of claims 1 to 17 produced or according Claim 18 are formed. Power plant with at least one steam generator for operation at least a turbine that has a generator for generating electrical energy drives, as well as with at least one heat exchanger, preferably Condenser equipped with finned tubes, which according to the Process according to at least one of Claims 1 to 17 or are formed according to claim 18.

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