Heater and a heat exchanger installation

Abstract

A heater comprises an inlet for a medium to be heated, an outlet for the medium, and at least two cassettes. Each cassette comprising a first plate comprising a first main surface and a second plate comprising a second main surface. The first and second plates are attached to each other and enclose a respective flow channel for the medium. The cassettes are arranged beside each other with a space between the cassettes for an electric heating element. The electric heating element abuts the first main surface of one of the cassettes and the second main surface of the adjacent cassette. The heater comprises two distance members extending between the one cassette and the adjacent cassette. The distance members define the space.

Claims

1. A heater comprising an inlet for a medium to be heated, an outlet for the medium, at least two cassettes, each cassette comprising a first plate comprising a first main surface and a second plate comprising a second main surface, wherein the first plate and the second plate are permanently joined to each other and enclose a respective flow channel for the medium between the first and second plates, and wherein the cassettes are arranged beside each other with a space between the cassettes, an electric heating element provided in the space between the cassettes, wherein the electric heating element abuts the first main surface of one of the cassettes and the second main surface of the adjacent cassette, the electric heating element being an elongated heating element that extends along a circuitous path in the space between the cassettes, two distance members extending between said one cassette and said adjacent cassette, wherein the distance members define said space, and the first and second main surfaces of each cassette being permanently connected to one another by way of a plurality of depressions extending inwardly from at least the first main surface of the first plate of the cassette toward the second main surface of the respective cassette, the plurality of depressions being positioned in the flow channel and being spaced apart from one another.

2. A heater according to claim 1, wherein each cassette comprises at least two openings permitting a flow of the medium from the flow channel of said one cassette to the flow channel of said adjacent cassette.

3. A heater according to claim 2, wherein at least one of the openings of said one cassette is provided opposite to one of the openings of said adjacent cassette and wherein the distance members surround said openings and permit said flow through said openings.

4. A heater according to claim 1, wherein each distance member comprises a ring defining two planar joining areas abutting the second main surface of said one cassette and the first main surface of said adjacent cassette.

5. A heater according to claim 1, wherein each distance member comprises at least one projection extending from the second main surface of said one cassette and from the first main surface of said adjacent cassette.

6. A heater according to claim 5, wherein each distance member comprises one projection extending from the second main surface or from the first main surface, and wherein each projection comprises a planar joining area abutting the first main surface or the second main surface of an adjacent cassette.

7. A heater according to claim 5, wherein each distance member comprises a first projection and a second projection, wherein the second plate of said one cassette comprises two second projections, which extend outwardly from the second main surface, and the first plate of said another adjacent cassette comprises two first projections, which extend outwardly from the first main surface, and wherein the first projections of said one cassette are abutting the second projections of said adjacent cassette to define said space.

8. A heater according to claim 7, wherein each of the first and second projections comprises a planar joining area, and the planar joining areas of the second projections of said one cassette are abutting the planar joining areas of the first projections of said adjacent cassette of the heater.

9. A heater according to claim 1, wherein the inlet is in flow communication with the flow channels of the cassettes, and the outlet is in flow communication with the flow channels of the cassettes, so that the heater permits the medium to flow into the inlet, through the flow channels and out through the outlet.

10. A heater according to claim 1, wherein the first main surface and the second main surface are substantially planar.

11. A heater according to claim 1, wherein each first plate comprises a first flange extending around the first plate and away from the first main surface, each second plate comprises a second flange extending around the second plate and away from the second main surface, and the first plate and the second plate are joined to each other by means of a joint extending along an outer edge of the first flange and an outer edge of the second flange.

12. A heater according to claim 1, wherein at least one of the depressions extending from the first main surface abuts a depression extending from the second main surface.

13. A heater according to claim 1, wherein the electric heating element comprises an electrical resistance wire.

14. A heat exchanger installation comprising a heat exchanger and a heater according to claim 1.

15. A heater according to claim 1, wherein each distance member comprises at least one projection extending from the second main surface of said one cassette or from the first main surface of said adjacent cassette.

16. A heater comprising an inlet for a medium to be heated, an outlet for the medium, at least two cassettes, each cassette comprising a first plate comprising a first main surface and a second plate comprising a second main surface, wherein the first plate and the second plate are permanently joined to each other and enclose a respective flow channel for the medium between the first and second plates, and wherein the cassettes are arranged beside each other with a space between the cassettes, an electric heating element in the space between the cassettes, the electric heating element abutting the first main surface of one of the cassettes and the second main surface of the adjacent cassette, the electric heating element including opposite ends connectable to a current source and winding back and forth within the space so that portions of the electric heating element between the opposite ends are spaced apart from one another in the space, two distance members extending between the one cassette and the adjacent cassette, wherein the distance members define the space, the first main surface of the first plate of each cassette being permanently connected to the second main surface of the second plate of the respective cassette by way of at least three depressions extending inwardly from at least the first main surface of the first plate toward the second main surface, the at least three depressions being positioned in the flow channel and being spaced apart from one another, the at least three depressions comprising a first depression, a second depression and a third depression, and one of the portions of the electric heating element passing between the first and second depressions as seen in plan view of the first and second cassettes, and another one of the portions of the electric heating element passing between the second and third depressions as seen in plan view of the first and second cassettes.

17. A heater according to claim 16, wherein at least one of the depressions extending from the first main surface abuts a depression extending from the second main surface.

18. A heater according to claim 16, wherein the first main surface is permanently connected to the second main surface by way of a plurality of depressions extending inwardly from the second main surface of the second plate toward the first main surface.

19. A heater according to claim 16, wherein each cassette comprises at least two openings permitting a flow of the medium from the flow channel of said one cassette to the flow channel of said adjacent cassette.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is now to be explained more closely through a description of preferred embodiments and with reference to the drawings attached hereto.

(2) FIG. 1 discloses a side view of a heater according to a first embodiment of the invention.

(3) FIG. 2 discloses front view of the heater in FIG. 1.

(4) FIG. 3 discloses a perspective view of a part of an electric heating element of the heater in FIG. 1.

(5) FIG. 4 discloses a side view of a cassette of the heater in FIG. 1.

(6) FIG. 5 discloses a side view of a cassette of a heater according to a second embodiment of the invention.

(7) FIG. 6 discloses a schematic side view of a heater according to a third embodiment with three cassettes arranged for a parallel flow of the medium.

(8) FIG. 7 discloses a schematic side view of a heater according to a fourth embodiment with two cassettes arranged for a parallel flow of the medium.

(9) FIG. 8 discloses a schematic side view of a heater according to a fifth embodiment with two cassettes arranged for a parallel flow of the medium.

(10) FIG. 9 discloses a schematic side view of a heater according to a sixth embodiment with three cassettes arranged for a serial flow of the medium.

(11) FIG. 10 discloses a schematic side view of a heater according to a seventh embodiment with two cassettes arranged for a serial flow of the medium.

(12) FIG. 11 discloses a schematic side view of a heater according to an eighth embodiment with two cassettes arranged for a serial flow of the medium.

(13) FIG. 12 discloses a schematic side view of a heater according to a ninth embodiment with two cassettes arranged for a serial flow of the medium.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

(14) A first embodiment of the heater is disclosed in FIGS. 1-4. The heater comprises an inlet 1 for a medium to be heated and an outlet 2 for the medium that has been heated. An inlet pipe 3 is provided upstream the inlet 1. An outlet pipe 4 is provided downstream the outlet 2.

(15) The heater may be a part of an installation comprising a heat exchanger HE, schematically indicated in FIG. 1.

(16) The inlet pipe 3 and/or the outlet pipe 4 may be parts of the heater or parts of the installation together with which the heater is to be used. The heater is then attached to the inlet pipe 3 and/or the outlet pipe 4 in any suitable manner, for instance by brazing, bonding, welding or gluing to form a permanent joint.

(17) The heater according to the first embodiment comprises two cassettes 5. Each cassette 5 comprises a first plate 6 and a second plate 7, see FIG. 4. The first plate 6 comprises a first main surface 8. The second plate 7 comprises a second main surface 9.

(18) Each cassette 5 has a first end 5a and an opposite second end 5b. In FIG. 1, the first end 5a is an upper end and the second end 5b a lower end. The heater may of course be used in other orientations, for instance the other way around so that the second end 5b forms an upper end and the first end 5a forms a lower end. Advantageously, the heater is vertically oriented, as indicated in the figures.

(19) In the first embodiment, the inlet 1 is provided at the first end 5a and the outlet 2 is provided at the first end 5a but on an opposite side of the heater.

(20) Both the first main surface 8 and the second main surface 9 are planar, or substantially planar, and extend in parallel with a common extension plane x, see FIG. 4.

(21) The first plate 6 and the second plate 7 are permanently joined to each other and enclose a flow channel 10 for the medium between the first plate 6 and the second plate 7, see FIG. 4.

(22) The first plate 6 comprises a first flange 11 extending around the first plate 6. The first flange 11 extends around and encloses the first main surface 8. The first flange 11 extends away from the first main surface 8, and is thus inclined in relation to the first main surface 8. In the embodiments disclosed the first flange 11 adjoins the first main surface 8.

(23) The second plate 7 comprises a second flange 12 extending around the second plate 7. The second flange 12 extends around and encloses the second main surface 9. The second flange 12 extends away from the second main surface 9, and is thus inclined in relation to the second main surface 9. In the embodiments disclosed, the second flange 12 adjoins the second main surface 9.

(24) The first plate 6 and the second plate 7 are permanently joined to each other by means of a joint extending along an outer edge area 13 of the first flange 11 and an outer edge area 14 of the second flange 12. As can be seen in FIG. 4, the outer edge area 13 of the first flange 11 and the outer edge area 14 of the second flange 12 are parallel with each other and with the common extension plane x. A secure permanent joint may be obtained between the edge areas 13 and 14 by means of brazing, bonding, welding or gluing to form a permanent joint between the first plate 6 and the second plate 7.

(25) In order to improve the strength of the cassette 5, a connecting member is provided in the flow channel 10. The connecting member connects the first main surface 8 to the second main surface 9.

(26) In the first embodiment, the connecting member comprises a plurality of depressions 15 extending inwardly from the first main surface 8 and one or more depressions 15 extending inwardly from the second main surface 9. The depressions 15 extending from the first main surface 8 abut a respective depression 15 extending from the second main surface 9, see FIG. 4.

(27) The depressions 15 are thus formed on and extend inwardly from the planar first and second main surfaces 8 and 9.

(28) The depressions 15 from the first main surface 8 are permanently joined to the depressions 15 from the second main surface 9 by means of brazing, bonding, welding or gluing. Preferably, the permanent joints between the edge areas 13 and 14 are made in the same joining step as the permanent joint of the connecting member, i.e. in the first embodiment as the joint the between the depressions 15.

(29) It is to be noted that depressions 15 may be provided on only one of the main surfaces 8 or 9, and then extend to the inner side of the opposing main surface 8 or 9.

(30) The heater also comprises two distance members 19 extending between one of the cassettes 5 and an adjacent cassette 5. The distance members 19 define a space 23 between the cassettes 5.

(31) In the first embodiment, each distance member 19 comprises a first projection 21 and a second projection 22. More precisely, the first plate 6 of each cassette 5 comprises two first projections 21, which extend outwardly from the first main surface 8, i.e. from the planar, or substantially planar, first main surface 8. One of the first projections 21 is provided at the first end 5a and the other first projection 21 at the second end 5b.

(32) The second plate 7 of each cassette 6 comprises two second projections 22, which extend outwardly from the second main surface 9, i.e. the planar, or substantially planar, second main surface 9. One of the second projections 22 is provided at the first end 5a and the other second projection 22 at the second end 5b.

(33) The first projections 21 of one of the two cassettes 5, to the right in FIGS. 1 and 4, are abutting the second projections 22 of the adjacent cassette 5, to the left in FIG. 1. Thanks to the first and second projections 21, 22, said space 23 is defined between the two cassettes 5, see FIG. 1, or between the first and second main surfaces 8 and 9 of adjacent cassettes 5. In particular, the space 23 is formed between the second main surface 9 of the cassette 5 to the left in FIG. 1 and the first main surface 8 of the cassette 5 to the right in FIG. 1.

(34) Each of the first projections 21 and the second projections 22 comprises a planar joining area 24, see FIG. 4. The planar joining areas 24 of the first projections 21 of one of the cassettes 5, to the right in FIG. 1, are abutting the planar joining areas 24 of the second projections 22 of the adjacent cassette 5 to the left in FIG. 1. The cassettes 5 may be permanently joined to each other by joining the abutting planar surfaces 24 of adjacent cassettes 5 to each other, for instance by means of brazing, bonding, welding or gluing.

(35) In the first embodiment, the first projection 21 at the first end 5a the cassette 5, to the left in FIG. 1, comprises an opening 26, see FIG. 4, forming the inlet 1 for the medium. In the same way the second projection 22 at the second end 5b of the same cassette 5 comprises an opening 26. Correspondingly, the first projection 21 at the second end 5b of the adjacent cassette 5 to the right in FIG. 1 comprises an opening 26 which is opposite to the second projection 22 at the second end 5b of the cassette 5 to the left to enable flow communication between the two cassettes 5. Furthermore, the second projection 22 at the first end 5a of the adjacent cassette 5 to the right also comprises an opening 26 forming the outlet 2 for the medium.

(36) Each of the openings 26 extends through a respective planar joining area 24 as can be seen in FIG. 4.

(37) The remaining projections 21 and 22 of the heater according to the first embodiment are closed.

(38) Consequently, as indicated in FIG. 1, the medium may flow in through the inlet pipe 3 and the inlet 1 of the opening 26 of one of the first projections 21, through the flow channel 10 of the cassette 5 to the left, through the openings 26 of the second projection 22 and the first projection 21 into the adjacent cassette 5, through the flow channel 10 of the adjacent cassette 5 and then out through the opening 26 of the second projection 22 to the outlet 2 and the outlet pipe 4.

(39) The cassettes 5 of the first embodiment are thus arranged to permit serial flow of the medium through the flow channels 10 of the cassettes 5.

(40) The heater also comprises an electric heating element 31 provided in the space 23 between the cassettes 5. The electric heating element 31 abuts the first main surface 8 of one of the cassettes 5 and the second main surface 9 of the adjacent cassette 5.

(41) The electric heating element 31 may be permanently joined to the first main surface 8 of one of the cassettes 5 and to the second main surface 9 of the adjacent cassette 5, for instance by means of brazing, bonding, welding or gluing.

(42) Preferably, the electric heating element 31 may be permanently joined to the first and second main surfaces 8, 9 in the same joining step as the joining of the connecting member, the joining of the edge surfaces 13 and 14, and the joining of the planar joining areas 24 to each other. In such a way, the heater may be joined as a complete unit in one single joining step. The joining enables the achievement an integrated heater.

(43) The electric heating element 31 comprises an electrical resistance wire 32, see FIG. 3. The electrical resistance wire 32 may be embedded in an insulation, such as a ceramic sleeve 33 of any suitable ceramic material.

(44) The electric heating element 31 comprises a metal tube 34, which surrounds the ceramic sleeve 33 and the electric resistance wire 32. The metal tube 34 forms the outer casing of the electric heating element 31.

(45) The electric heating element 31 may be suitable for being permanently joined to the adjoining first and second main surfaces 8 and 9 by brazing, bonding, welding or gluing as mentioned above.

(46) The metal tube 34 of the electric heating element 31 is, for instance, made of stainless steel. A metal tube 34 is suitable for such permanent joining. However, the electric heating element 31 may alternatively comprise an outer casing of other materials than metal, for instance a ceramic material, which also may be permanently joined to the first and second main surfaces 8 and 9.

(47) As can be seen in FIG. 1, the electric heating element 31 is connected to a current source 35 via the lines 36 in order to provide the electric current for operating the electric heating element 31 at a suitable temperature.

(48) Advantageously, the electric heating element 31 is provided in a central area of the first main surface 8 and the second main surface 9. For instance, the electric heating element 31 may extension between the two distance members 19 as in the embodiments disclosed, see especially FIG. 2. Thus, there are two end regions of the cassettes, which are not located adjacent to the electric heating element 31.

(49) FIG. 5 discloses a cassette 5 of a heater according to a second embodiment, which differs from the first embodiment in that the connecting member comprises a corrugated sheet 16 provided in the flow channel 10 between the first plate 6 and the second plate 7. The corrugation of the corrugated sheet 16 is configured to permit the medium to flow through the flow channel 10 from one of the openings 26 at one end to another of the openings 26 at the other end. Also the corrugated sheet 16 may be permanently joined to the first main surface 8 and the second main surface 9, for instance by means of brazing, bonding, welding or gluing.

(50) FIG. 6 discloses a third embodiment which differs from the first embodiment in that the heater comprises three cassettes in parallel flow through the flow channels 10 of the cassettes 5. The heater comprises two electric heating elements 31 arranged in a respective space 23 between the cassettes 5. The inlet 1 is provided at the first end 5a and the outlet 2 is provided at the second end 5b on the opposite side of the heater. The connecting member comprises protrusions 15 as in the first embodiment, but could be configured in other ways, for instance with a corrugated sheet 16 as in the second embodiment.

(51) FIG. 7 discloses a fourth embodiment which differs from the first embodiment in that the medium flows in parallel flow through the flow channels 10 of the two cassettes 5, and in that the inlet 1 and the outlet 2 are provided on the same side of the heater. The connecting member comprises protrusions 15 as in the first embodiment but could be configured in other ways, for instance with a corrugated sheet as in the second embodiment.

(52) FIG. 8 discloses a fifth embodiment which differs from the first embodiment in that the medium flows in parallel flow through the two cassettes and in that the inlet 1 is provided at the first end 5a and the outlet 2 is provided at the second end 5b on the opposite side of the heater. The connecting member comprises protrusions 15 as in the first embodiment, but could be configured in other ways, for instance with a corrugated sheet 16 as in the second embodiment.

(53) FIG. 9 discloses a sixth embodiment which differs from the first embodiment in that the heater comprises three cassettes. The heater comprises two electric heating elements 31 arranged in a respective space 23 between the cassettes 5. As in the first embodiment, the medium flows in serial flow through the flow channels 10. The inlet 1 is provided at the first end 5a and the outlet 2 is provided at the second end 5b on the opposite side of the heater. The connecting member comprises protrusions 15 as in the first embodiment but could be configured in other ways, for instance with a corrugated sheet as in the second embodiment.

(54) FIG. 10 discloses a seventh embodiment which differs from the first embodiment in that each distance member 19 comprises only one projection 21, 22. Each first plate 6 comprises one, or only one, first projection 21 extending from the first main surface 8. Each second plate 7 comprises one, or only one, second projection 22 extending from the second main surface 9. The first and second plates 6, 7 are identical and may be rotated to achieve various configurations regarding the position of the inlet 1 and the outlet 2, for instance as exemplified in FIGS. 6 to 9, and also with respect to parallel or serial flow of the medium. The inlet pipe 3 and the outlet pipe 4 are directly attached to the first main surface 8 and the second main surface 9, respectively.

(55) FIG. 11 discloses an eighth embodiment which differs from the first embodiment in that each distance member 19 comprises only one projection 21, 22. Each second plate 7 comprises two second projections 22 extending from the second main surface 9 to the first main surface 8 of the adjacent cassette 5. The first plates 6 comprise no projections. The inlet pipe 3 is attached to the first main surface 8. The outlet pipe 4 is attached to one of the second projections 22.

(56) FIG. 12 discloses a ninth embodiment which differs from the first embodiment in that each distance member 19 comprises a ring 20. The first and second plates 6 have no projections, but the ring 20 extends from the second main surface 9 of one of the cassettes 5 to the first main surface 8 of the adjacent cassette 5. Each ring 20 defines two planar joining areas 24 abutting and joined to the second main surface 9 of one of the cassettes 5 and the first main surface 8 of the adjacent cassette 5. The first and second plates 6, 7 are identical except for the positions and number of openings 26. The inlet pipe 3 and the outlet pipe 4 are directly attached to the first main surface 8 and the second main surface 9, respectively.

(57) The present invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.

(58) It is to be noted that further configurations of the heater are possible, for instance 4, 5, 6 or even more cassettes 5 arranged to permit the medium to flow in parallel flow or serial flow.

(59) Furthermore, at least the first and second plates 6 and 7 that face each other in the heater may have projecting members extending outwardly into the space 23 from the planar first main surface 8 and the planar second main surface 9, respectively. Such projecting members may facilitate the positioning of the electric heating element 31 during the joining of the heater.

(60) It is also to be noted that the cassettes 5 and the electric heating element 31 may be joined together by means of tie bolts, as an alternative to the permanent joining discussed above. The first and second plates 6 and 7 and the connecting member between the plates are still permanently joined as described above.