Coiled heat exchanger having inserts between the shroud and the last pipe layer

Abstract

A heat exchanger, providing indirect heat transfer between a first fluid and at least one second fluid, comprises a jacket enclosing a jacket space for accommodating the first fluid and a tube bundle arranged in the jacket space and having a plurality of tubes for accommodating the at least one second fluid. The tubes form multiple tube layers. A shroud arranged in the jacket space encloses an outermost tube layer of the tube bundle. Spacers extending along the longitudinal axis are arranged between the shroud and the outermost tube layer. An interspace is present between any two spacers adjacent in the circumferential direction of the shroud, and between the shroud and the uppermost tube layer. A flow obstruction is arranged in the respective interspace and is designed to prevent or suppress a flow of the first fluid in the respective interspace, at least over a part section thereof.

Claims

1. A heat exchanger for the indirect exchange of heat between a first fluid and at least one second fluid comprising: a shell which extends along a longitudinal axis and surrounds a shell space for receiving the first fluid, a bundle of tubes, arranged in the shell space, comprising a plurality of tubes for receiving the at least one second fluid, wherein the tubes form a number of tube layers, and a shroud which is arranged in the shell space and encloses an outermost tube layer of the bundle of tubes in the radial direction of the bundle of tubes, wherein spacers that extend along the longitudinal axis are arranged between the shroud and the outermost tube layer, and wherein between every two spacers adjacent to one another in the circumferential direction of the shroud and the shroud and the outermost tube layer there is an intermediate space that extends along the longitudinal axis, wherein a flow obstacle is arranged in each intermediate space and is designed to hinder or suppress a flow of the first fluid in the intermediate space at least over a partial portion of the intermediate space that extends along the longitudinal axis, and wherein each flow obstacle comprises a flexible layer of material, and wherein each intermediate space has a cross-sectional area perpendicularly to the longitudinal axis and a length along the direction of the longitudinal axis, and wherein, along the length in the direction of the longitudinal axis the respective flow obstacle takes up over 50% of the cross-sectional area of the intermediate space.

2. The heat exchanger as claimed in claim 1, wherein the respective flow obstacle extends in the circumferential direction of the shroud over the entire circumferential extent of the respective intermediate space between the spacers.

3. The heat exchanger as claimed in claim 1, wherein the flexible layer of material comprises polytetrafluoroethylene or is formed from polytetrafluoroethylene.

4. The heat exchanger as claimed in claim 1, wherein each flow obstacle has a supporting structure.

5. The heat exchanger as claimed in claim 4, wherein the supporting structure is formed in the manner of a plate.

6. The heat exchanger as claimed in claim 4, wherein the supporting structure comprises a metal or is formed from a metal.

7. The heat exchanger as claimed in claim 4, wherein each supporting structure has an upper edge, a front side, and a rear side which faces away from the front side of the supporting structure, and wherein the flexible layer of material is placed or guided around the upper edge of the supporting structure so that the flexible layer of material at least partially covers the upper edge, the rear side and the front side of the supporting structure.

8. The heat exchanger as claimed in claim 4, wherein the supporting structure is integrally formed on the flexible layer of material or the flexible layer of material is integrally formed on the supporting structure.

9. The heat exchanger as claimed in claim 4, wherein the respective flow obstacle is arranged in the assigned intermediate space with a portion of the flexible layer of material placed or guided around an upper edge of the supporting structure.

10. The heat exchanger as claimed in claim 4, wherein the flexible layer of material having a modulus of elasticity in compression in the range from 100 to 1000 MPa.

11. The heat exchanger as claimed in claim 1, wherein the respective flow obstacle only extends along a lower portion of the bundle of tubes in the respective intermediate space.

12. The heat exchanger as claimed in claim 1, wherein, for forming the tube layers, the tubes are in each case coiled onto a core tube of the heat exchanger that is designed for absorbing the load of the tubes, wherein the heat exchanger has further spacers between the respective tube layer and the tube layer lying thereunder in each case, arranged further inward in the radial direction, wherein said further spacers extend in each case along the longitudinal axis.

13. The heat exchanger as claimed in claim 1, wherein the flow obstacle takes up over 60% of the cross-sectional area of the intermediate space.

14. The heat exchanger as claimed in claim 1, wherein the respective flow obstacle takes up over 70% of the cross-sectional area of the intermediate space.

15. The heat exchanger as claimed in claim 1, wherein respective flow obstacle takes up over 80% of the cross-sectional area of the intermediate space.

16. The heat exchanger as claimed in claim 1, wherein respective flow obstacle takes up over 90% of the cross-sectional area of the intermediate space.

17. A method for arranging flow obstacles in a heat exchanger having a shell that extends along a longitudinal axis and surrounds a shell space for receiving a first fluid, wherein the heat exchanger also has a bundle of tubes arranged in the shell space and comprising a plurality of tubes for receiving at least one second fluid, which form a number of tube layers, and a shroud arranged in the shell space and which encloses an outermost tube layer of the bundle of tubes in the radial direction of the bundle of tubes, wherein spacers that are made to extend along the longitudinal axis are arranged between the shroud and the outermost tube layer, wherein between every two spacers adjacent to one another in the circumferential direction of the shroud and the shroud and the outermost tube layer there is an intermediate space, said method comprising pushing a flow obstacle into the respective intermediate space, wherein said flow obstacle is designed to hinder or suppress a flow of the first fluid in the respective intermediate space at least over a partial portion of the respective intermediate space that extends along the longitudinal axis, wherein each flow obstacle comprises a flexible layer of material, and wherein each intermediate space has a cross-sectional area perpendicularly to the longitudinal axis and a length along the direction of the longitudinal axis, and wherein, along the length in the direction of the longitudinal axis the respective flow obstacle takes up over 50% of the cross-sectional area of the intermediate space.

18. The method as claimed in claim 17, wherein the respective flow obstacle has a supporting structure with an upper edge, around which the flexible layer of material is placed, so that a portion of the flexible layer of material surrounds said upper edge, wherein the respective flow obstacle is pushed or guided into the respective intermediate space from below beginning with said portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the invention are to be explained by the following description of the figures of an exemplary embodiment by reference to the figures:

(2) in which:

(3) FIG. 1 shows a sectional view in the manner of a detail of a heat exchanger according to the invention;

(4) FIG. 2 shows a partially sectioned and perspective view in the manner of a detail of an upper tube layer of a heat exchanger according to the invention, wherein a shroud is arranged on the uppermost tube layer and is fixed to the uppermost tube layer by way of spacers, wherein flow obstacles are provided between the shroud and the uppermost tube layer (for the sake of overall clarity, only one flow obstacle is shown in FIG. 2); and

(5) FIG. 3 shows a sectional view of a flow obstacle according to the invention in the manner of FIG. 2.

(6) FIG. 1 shows in conjunction with FIGS. 2 and 3 an embodiment of a heat exchanger 1 according to the invention with a plurality of flow obstacles 300.

(7) The heat exchanger 1 is designed for the indirect exchange of heat between a first fluid S and at least one second fluid S and has a shell 10, which surrounds a shell space M for receiving the first fluid S, which can be introduced into the shell space M by way of an inlet nozzle 101 on the shell 10 and can be drawn off again from the shell space M by way of a corresponding outlet nozzle 102 on the shell 10, wherein the first fluid S acts from above on a bundle of tubes 2 of the heat exchanger arranged in the shell space M.

(8) The shell 10 of the heat exchanger 1 extends along a longitudinal axis z, which runs along the vertical with respect to a state of the heat exchanger 1 arranged as intended. The bundle of tubes 2 has a plurality of tubes 20 for receiving the at least one second fluid S. Various second fluids S may be carried in assigned tubes or groups of tubes of the bundle of tubes 2, i.e. the bundle of tubes 2 is divided in a way corresponding to the number of second fluids S to be carried. The tubes 20 are coiled helically onto a core tube 21 so as to form a number of layers of tubes 200, 201, which are arranged one above the other in a radial direction R, which is perpendicular to the longitudinal axis z, wherein the core tube 21 likewise extends along the longitudinal axis z and is arranged concentrically in the shell space M. Furthermore, the individual tube layers 200, 201 are fixed to one another by way of spacers 6 made to extend along the longitudinal axis z, wherein in each case a number of spacers 6 are arranged one above the other in the radial direction R of the bundle of tubes 2. In this case, a constant number of spacers 6 is preferably provided between the adjacent tube layers.

(9) A number of tubes 20 may be respectively brought together in a tubesheet 104, wherein the second fluid S or a number of second fluids S can be introduced into each tube 20 by way of inlet nozzles 103 on the shell 10 and can be drawn off from the tubes 20 by way of outlet nozzles 105. Consequently, heat can be exchanged indirectly between the first fluid S and the at least one second fluid S, wherein these fluids S, S are for example passed through the heat exchanger 1 in countercurrent.

(10) The shell 10 and the core tube 21 are at least in certain portions configured in the form of a cylinder, so that the longitudinal axis z forms a cylinder axis of the shell 10 and of the core tube 21 running concentrically therein. Also arranged in the shell space M is a preferably hollow-cylindrically formed shroud 3, which encloses the bundle of tubes 2, so that an annular gap surrounding the bundle of tubes 2 is formed between the bundle of tubes 2 and each shroud 3. Arranged in this gap are spacers 60, which are made to extend along the longitudinal axis z and are used to fix the shroud 3 to the bundle of tubes 2, in particular to the outermost tube layer 200. Said spacers 60 preferably extend along the longitudinal axis z over the entire length of the bundle of tubes 2 and are in each case preferably formed so as to be elastically deformable in the radial direction R, in order to be able to compensate for thermally induced stresses between the bundle of tubes 2 and the shroud 3. On account of the spacers 60, between the shroud 3 and the outermost tube layer 200 there is between every two spacers 60 adjacent to one another in the circumferential direction U of the shroud 3 an intermediate space M, which is made to extend along the longitudinal axis z.

(11) Preferably arranged in these intermediate spaces M are flow obstacles 300, which in the ideal case completely prevent a bypass flow of the first fluid S in the intermediate spaces M in the region of the flow obstacles 300, or in particular at least hinder these flows in such a way that a significant increase in the effectiveness of the heat exchanger 1 is achieved, or it is provided that at least part of the fluid S (preferably the entire fluid S) is returned into the bundle 2 from the respective intermediate space M.

(12) According to one embodiment, the flow obstacles 300 have a supporting structure 302 (for example in the form of a rectangular metal sheet) and a layer of material 301, which for example consists of PTFE and is placed around an upper edge 302b of the supporting structure 302, so that the layer of material 301 covers this upper edge 302b and a front side 302a of the supporting structure 302 that is facing the shroud 3 and a rear side 302c of the supporting structure 302 that is facing away from the front side 302a with corresponding portions 301a, 301b, 301c. Here, the supporting structure 302 serves for stiffening the layer of material 301 of the respective flow obstacle 300, which is inserted, preferably in each case from below, in a direction of insertion E (cf. FIGS. 2 and 3) with the portion 301b that has been placed around the respective upper edge 302b into the assigned intermediate space M and pushed in the upward direction. For example in the case of an upright heat exchanger 1, here the direction of insertion E points upward in the vertical direction along the longitudinal axis z. The flow obstacles 300 may of course also be introduced into a heat exchanger 1 that is lying down, wherein the direction of insertion E is correspondingly oriented horizontally in each case. Preferably, the respective flow obstacle 300, arranged as intended, tightly fills at least a lower portion of the respective intermediate space M, and consequently preferably prevents a bypass flow of the first fluid S past the bundle of tubes 2 in this region.

(13) Such sealing can be advantageously provided as a retrofit on already existing helically coiled heat exchangers 1.

(14) TABLE-US-00001 List of reference signs 1 Heat exchanger 2 Bundle of tubes 3 Shroud 6 Spacer 10 Shell 20 Tubes 21 Core tube 60 Outermost spacers 101 Inlet nozzle 102 Outlet nozzle 103 Inlet nozzle 104 Tubesheet 105 Outlet nozzle 200 Outermost tube layer 201 Tube layer 300 Flow obstacle 301 Layer of material 301a, 301b, 301c Portions of layer of material 302 Supporting structure 302a Front side 302b Upper edge 302c Rear side E Direction of insertion R Radial direction Z Longitudinal axis M Shell space M Intermediate space U Circumferential direction