FLAT TUBE HEAT EXCHANGER

Abstract

The invention relates to a flat tube heat exchanger, in particular to a high-temperature flat tube heat exchanger for gaseous media, comprising a closed housing (5) having a tube bundle space (50) and a tube bundle, arranged in the tube bundle space (50) of the housing (5), comprising multiple flat tubes (2), there being arranged, in the flat tubes (2) and in the tube bundle space (50) between the flat tubes (2), corrugated strips (3, 6) having peaks (30, 60) and troughs (31, 61) extending in the longitudinal direction of the flat tubes (2), wherein the peaks (30, 60) and troughs (31, 61) respectively bear internally and externally against flat sides (200) of the flat tubes (2), and wherein there is provided a device for externally applying a surface pressure to the housing (5), at least in the region of the tube bundle space (50), this pressure being higher than a pressure (p1, p2) of the media guided in the flat tubes (2) or around the flat tubes (2).

Claims

1. A flat-tube heat exchanger, in particular for gaseous media, comprising a closed housing having a tube bundle space and a tube bundle which is arranged in the tube bundle space of the housing and which comprises a plurality of flat tubes, wherein corrugated bands having peaks and troughs extending in a longitudinal direction of the flat tubes are arranged in the flat tubes and in the tube bundle space between the flat tubes, wherein the peaks and troughs bear internally or externally against flat sides of the flat tubes, and in that provision is made of an apparatus which is suitable, and configured, for externally applying a surface pressure to the housing, at least in the region of the tube bundle space said surface pressure being higher than a pressure of the media guided in the flat tubes or around the flat tubes.

2. The flat-tube heat exchanger as claimed in claim 1, wherein a surface pressure which is about 1 bar to about 4 bar higher than a pressure of the media guided in the flat tubes or around the flat tubes is applied to the housing by means of the apparatus.

3. The flat-tube heat exchanger as claimed in claim 1, wherein the corrugated bands have a sinusoidal, triangular or sawtooth wave shape.

4. The flat-tube heat exchanger as claimed in claim 1, wherein a width of the corrugated bands which are arranged in the flat tubes is at least equal to a width of the flat sides of the flat tubes.

5. The flat-tube heat exchanger as claimed in claim 1, wherein the peaks and troughs of the corrugated bands bear freely against flat sides of the flat tubes.

6. The flat-tube heat exchanger as claimed in claim 1, wherein the apparatus comprises a casing housing which accommodates the housing, wherein the casing housing surrounds the housing, at least in the region of the tube bundle space, with a spacing so as to leave a pressure space.

7. The flat-tube heat exchanger as claimed in claim 6, wherein the casing housing is in the form of a pressure vessel having a connection for media supply and/or media discharge, wherein a pressure in the pressure vessel can be regulated by media supply and/or media discharge.

8. The flat-tube heat exchanger as claimed in claim 1, wherein the apparatus comprises a pair of bars and/or plates having two flexurally rigid bars or plates which are movable relative to one another and which are connected by means of tie rods, wherein at least one portion of the housing is arranged between the bars or plates of the pair of bars and/or plates.

9. The flat-tube heat exchanger as claimed in claim 8, wherein the apparatus comprises a casing housing, wherein the casing housing surrounds the housing, at least in the region of the tube bundle space, with a spacing.

10. The flat-tube heat exchanger as claimed in claim 9, wherein thermal insulation is provided between the casing housing and the housing.

11. The flat-tube heat exchanger as claimed in claim 1, wherein the flat-tube heat exchanger is constructed in the form of a rectangular arrangement with a cuboid tube bundle space and with a plurality of flat tubes arranged in rows and columns.

12. The flat-tube heat exchanger as claimed in claim 1, wherein the corrugated bands are at least partially coated with a material acting as a catalyst.

13. The flat-tube heat exchanger as claimed in claim 1, wherein, as viewed in the longitudinal direction, in each case at least two corrugated bands are arranged so as to run oppositely in the flat tubes.

14. The flat-tube heat exchanger as claimed in claim 13, wherein transverse ribs are arranged between two adjacent corrugated bands.

15. The flat-tube heat exchanger as claimed in claim 1, wherein the flat tubes are each composed of at least two flat tube pieces which each extend in the longitudinal direction.

16. The flat-tube heat exchanger as claimed in claim 9, wherein pressure rams for force transmission are arranged between the casing housing and the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further advantages and aspects of the invention emerge from the claims and from the following description of exemplary embodiments of the invention, which are explained below on the basis of the schematic figures. In the drawings:

[0027] FIG. 1 shows a longitudinal section of a flat tube for a flat-tube heat exchanger, wherein a corrugated band having peaks and troughs extending in the longitudinal direction of the flat tube is arranged in the flat tube,

[0028] FIG. 2 shows the flat tube according to FIG. 1 in cross section along section line II-II according to FIG. 1,

[0029] FIG. 3 shows the flat tube according to FIG. 1 in cross section along section line III-III according to FIG. 1,

[0030] FIG. 4 shows a longitudinal section of a tube bundle space of a flat-tube heat exchanger having a plurality of flat tubes according to FIG. 1,

[0031] FIG. 5 shows a plan view of the tube bundle space according to FIG. 4,

[0032] FIG. 6 shows the tube bundle space according to FIG. 4 in cross section along section line VI-VI according to FIG. 4,

[0033] FIG. 7 shows a longitudinal section of a first configuration of a flat-tube heat exchanger having a plurality of flat tubes, wherein a housing of the flat-tube heat exchanger is surrounded by a casing housing in the form of a pressure vessel,

[0034] FIG. 8 shows the flat-tube heat exchanger according to FIG. 7 in cross section along section line VIII-VIII according to FIG. 7,

[0035] FIG. 9 shows a longitudinal section of a second configuration of a flat-tube heat exchanger having a plurality of flat tubes, wherein a housing of the flat-tube heat exchanger is surrounded by a casing housing to which a surface pressure is applied by means of a plurality of pairs of bars,

[0036] FIG. 10 shows a flat-tube heat exchanger according to FIG. 9 in cross section along section line X-X according to FIG. 9,

[0037] FIG. 11 shows a perspective illustration of an alternative arrangement of corrugated bands, and

[0038] FIG. 12 shows a cross section of a flat tube with the arrangement of corrugated bands according to FIG. 11.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0039] In the following description of exemplary embodiments of the invention, the same reference designations are used for the same or similar components.

[0040] FIGS. 1 to 3 show a flat tube 2 for a flat-tube heat exchanger 1 (cf. FIGS. 7 to 10), which is not illustrated in FIGS. 1 to 3, in longitudinal section and in two cross sections along section lines II-II and according to FIG. 1.

[0041] The flat tube 2 has two ends 21, 22 and a central portion 20 lying between the two ends 21, 22. A cross section of the central portion 20 has a stadium shape with two mutually parallel planar flat sides 200 and two narrow sides 201 which connect the flat sides 200 and which are curved, for example curved in a semicircular manner in the exemplary embodiment illustrated. The ends 21, 22 have a cross section, which differs from the central portion 20, for a connection to collecting spaces of a housing of the flat-tube heat exchanger 1 (not illustrated), for example a circular cross section.

[0042] Two corrugated bands 3 having peaks 30 and troughs 31 (cf. FIGS. 2 and 3) extending in the longitudinal direction L of the flat tube are arranged in the flat tube 2, more precisely in the central portion 20 of the flat tube 2. In the exemplary embodiment illustrated, the two corrugated bands 3 have a sinusoidal wave shape. The peaks 30 and troughs 31 have the same shape. Peaks 30 refer to those amplitudes of the corrugated bands 3 which protrude upward in the plane of the drawing; it would equally be conceivable for the amplitudes which protrude downward in the plane of the drawing to be referred to as peaks.

[0043] The corrugated bands 3 illustrated each have a constant height, and the peaks 30 and troughs 31 touch opposite inner surfaces of the flat sides 200 of the flat tubes 2. A width of the corrugated bands 3 is approximately equal to a width of the flat sides 200.

[0044] The flat tube 2 illustrated in FIG. 1 is composed of two flat tube pieces 2a, 2b which each extend in the longitudinal direction L. The flat tube pieces 2a, 2b are arranged in a mirror-symmetrical manner and are welded to one another along a weld seam 4. In the exemplary embodiment illustrated, the flat tube pieces 2a, 2b have at least substantially the same length. In one configuration, the flat tube pieces 2a, 2b are manufactured from various materials, wherein each flat tube piece 2a, 2b can be optimized for a temperature zone of an associated flat-tube heat exchanger. The flat tube pieces are welded to one another along a weld seam 4.

[0045] In the exemplary embodiment illustrated, a respective corrugated band 3 is provided in the flat tube pieces 2a, 2b, wherein the wave shape of the corrugated bands 3 is identical and the corrugated bands 3 are arranged in alignment with one another. In other configurations, the corrugated bands 3 arranged in the flat tube pieces 2a and 2b differ in terms of wave shape or number of waves. In yet other configurations, provision is made of a corrugated band 3 which extends beyond both flat tube pieces 2a, 2b.

[0046] FIGS. 4 to 6 respectively show a tube bundle space 50 of a closed housing 5 (illustrated only in part) of a flat-tube heat exchanger 1 (cf. FIGS. 7 to 10), which is not illustrated in FIGS. 4 to 6, in longitudinal section, in plan view and in cross section along section line VI-VI according to FIG. 4.

[0047] The tube bundle space 50 illustrated has a cuboid shape. A tube bundle having a plurality of flat tubes 2 according to FIG. 1 is arranged in the tube bundle space 50, a rectangular arrangement of the flat tubes 2 being provided in the exemplary embodiment illustrated. The tube bundle comprises fifty flat tubes 2, which are arranged in ten rows each comprising five flat tubes 2 which are arranged next to one another and the flat sides 200 of which lie in common planes. The number of rows and the number of flat tubes 2 per row are exemplary here, more or fewer rows are provided in other configurations. The ends 21, 22 of the flat tubes 2 are fastened in tube sheets 52.

[0048] Corrugated bands 3 as described above are arranged in the flat tubes 2, more precisely in the central portions 20 thereof (cf. FIG. 1). In addition, corrugated bands 6, the peaks 60 and troughs of which bear externally against the flat sides 200 of the flat tubes 2, are likewise provided between the rows of flat tubes 2. In the exemplary embodiment illustrated, the corrugated bands 6 arranged between the flat tubes 2 likewise have a sinusoidal wave shape. A height of these corrugated bands 6 corresponds at least approximately to a spacing between two rows of the flat tubes 2. In the exemplary embodiment illustrated, the corrugated bands 6 each extend over the entire row. In other configurations, two or more corrugated bands are provided per row.

[0049] As indicated schematically in FIG. 6 by way of arrows, a surface pressure is applied to the housing 5 in the region of the tube bundle space 50. The surface pressure is higher, in particular about 1 to 4 bar higher, than a pressure of the media guided in the flat tubes 2 or around the flat tubes 2. The surface pressure ensures that contact of the corrugated bands 3, 6 with the flat tubes 2 on the inner and outer sides is maintained during operation, without this requiring a materially bonded connection, in particular a welded or soldered connection, between the flat tubes 2 and the corrugated bands 3, 6. The surface pressure can be applied by a suitable apparatus.

[0050] FIGS. 7 and 8 respectively show a first exemplary embodiment of a flat-tube heat exchanger 1 having a plurality of flat tubes 2 in longitudinal section and in cross section along section line VIII-VIII according to FIG. 7, wherein a housing 5 is surrounded by a casing housing 7 in the form of a pressure vessel.

[0051] The housing 5 comprises a tube bundle space 50, and input-side collecting space 54, an output-side collecting space 56, and two tube bundle space connections 58. The tube bundle space 50 is separated from the collecting spaces 54, 56 by means of tube sheets 52. The tube sheets 52 comprise connections for the schematically illustrated flat tubes 2, such that a medium which is supplied to the input-side collecting space 54 and which has a pressure p1 can flow from the input-side collecting space 54 into the flat tubes 2 and from the flat tubes 2 into the output-side collecting space 56.

[0052] The flat-tube heat exchanger 1 illustrated is preferably operated in counter-flow, wherein a medium which is guided around the flat tubes 2 and which has a pressure p2 is supplied via a tube bundle space connection 58, illustrated at the top in the plane of the drawing, and flows from there into the tube bundle space 50.

[0053] The casing housing 7 in the form of a pressure vessel surrounds the housing 5 with a spacing so as to leave a pressure space 70. As schematically illustrated in FIG. 8, the casing housing 7 has a connection 72 for media supply and/or media discharge, such that a pressure p in the casing housing 7 can be regulated by media supply and/or media discharge. The pressure p in the pressure space 70 of the casing housing 7, in the form of a pressure vessel, is in this case selected in such a way that it is higher, in particular about 1 bar to about 4 bar higher, than the pressure p1, p2 of the media guided in the flat tubes 2 or around the flat tubes 2. As a result, a surface pressure is externally applied to the housing 5 and ensures that the corrugated bands 3, 6 (cf. FIGS. 1 to 6), which are not illustrated in FIGS. 7 and 8, bear against the flat tubes 2 even without a materially bonded connection.

[0054] The rectangular arrangement of the flat tubes 2 illustrated in FIGS. 7 and 8 is merely exemplary. In other configurations, differing arrangements, in particular ring arrangements, of the flat tubes 2 are provided, as described in EP 2 584 201 A1. Reference is hereby made to the entire disclosure of EP 2 584 201 A1.

[0055] FIGS. 9 and 10 respectively show a second configuration of a flat-tube heat exchanger 1 having a plurality of flat tubes 2 in longitudinal section and in cross section along section line X-X according to FIG. 9. The flat-tube heat exchanger 1 illustrated in FIGS. 9 and 10 is part of a schematically illustrated installation for thermal post-combustion (TNV), wherein contaminated air or an offgas is supplied via an input-side collecting space 54 to the flat tubes 2, and from there passes into a schematically illustrated combustion space 9. The burned offgas flows from the combustion space 9 into the tube bundle space 50, and is discharged to the surroundings via the tube bundle space connection 58. In this case, the offgas and the burned offgas usually flow in and around the flat tubes 2 only at moderate overpressure.

[0056] Corrugated bands 3, 6 (cf. FIGS. 1 to 6), which are not illustrated in FIGS. 9 and 10, are arranged in the flat tubes 2 and, depending on the configuration, additionally also around the flat tubes 2, wherein an apparatus for applying a surface pressure to the housing 5 is provided, in order to ensure contact between the flat tubes and the corrugated bands 3, 6.

[0057] For this purpose, in the exemplary embodiment illustrated in FIGS. 9 and 10, the housing 5 of the flat-tube heat exchanger 1 is also surrounded by a casing housing 7. Furthermore, provision is made of a plurality of pairs of bars, four pairs of bars 8 in the exemplary embodiment illustrated. The pairs of bars 8 each comprise two bars 80 connected by means of tie rods 82. In one configuration, spring elements are provided on the tie rods 82, said spring elements being used to brace the bars 80 with one another with a defined force. For this purpose, in other configurations, provision is alternatively or additionally made of adjusting elements, in particular adjusting screws, which can be adjusted manually or by motor. The pairs of bars 8 are used to apply a surface pressure to the casing housing 7. The application is transferred to the housing 5. For this purpose, in the exemplary embodiment illustrated, pressure rams 84, which are designed to apply a surface pressure to the housing 5 in a uniform manner, are arranged between the casing housing 7 and the housing 5.

[0058] In the exemplary embodiment illustrated, the flat tubes 2 are in a rectangular arrangement. Therefore, an application of force in a direction perpendicular to the direction of the rows of flat tubes 2 is sufficient to ensure contact between the flat tubes 2 and the corrugated bands 3 arranged therein, and also between the flat tubes 2 and the corrugated bands 6 arranged between the rows. By contrast, in the case of a flat-tube heat exchanger with a ring arrangement, provision is made of an apparatus which can be used to apply forces acting in a radial direction of the ring arrangement.

[0059] In the exemplary embodiment illustrated, thermal insulation 88 is provided between the housing 5 and the casing housing 7.

[0060] In an alternative configuration, the casing housing 7 is omitted, in which case a surface pressure is applied to the housing 5 directly by means of the pairs of bars 8.

[0061] According to the exemplary embodiments illustrated in FIGS. 1 to 6, in each case two corrugated bands 3 having mutually aligned peaks 30 and troughs are arranged in the flat tubes 2.

[0062] FIG. 11 shows a perspective illustration of an alternative arrangement of corrugated bands 3. In the arrangement according to FIG. 11, as viewed in a longitudinal direction L, a plurality of corrugated bands 3 having peaks 30 and troughs 31 extending in the longitudinal direction L are arranged so as to alternately run oppositely. In other words, the peaks 30 and troughs 31 of successive corrugated bands 3 are in each case phase-shifted by 180°. Transverse ribs 34 are also arranged between successive corrugated bands 3.

[0063] FIG. 12 shows a cross section of a flat tube 2 with the arrangement of corrugated bands 3 according to FIG. 11.

[0064] Due to the alternately oppositely running arrangement of the corrugated bands 3 according to FIGS. 11 and 12, swirling of the flow for improved heat transfer is achieved.

[0065] According to the invention, an arrangement of corrugated bands 3 in the flat tubes 2 and additionally also on outer sides of the flat tubes 2 has the effect that the size of a transfer surface for heat transfer is increased and thus the efficiency of a flat-tube heat exchanger 1 is increased. In this case, welded and/or soldered connections between the corrugated bands 3, 6 and the flat tubes 2 can be omitted, in that contact between the corrugated bands 3, 6 and the flat tubes 2 is ensured, even during operation, by application of a surface pressure to a housing 5 of the flat-tube heat exchanger 1.