INSULATING SURFACE COATING ON HEAT EXCHANGERS FOR REDUCING THERMAL STRESSES

Abstract

The invention relates to a plate heat exchanger (10) having a plate heat exchanger block (11), which has a plurality of partitions (4, 5) arranged parallel to one another in the form of separating plates which form a plurality of heat exchange passages (1a, 1b) for fluids which are to be brought into indirect heat exchange relationship with one another. The heat exchange passages are closed off from the outside by lateral strips (8), and each heat exchange passage (1a, 1b) has an inlet (9) for inflow of a fluid and an outlet (19) for outflow of the fluid. According to the invention, one or more partitions (4, 5) and/or one or more heat-conducting elements (2, 3) in each case have a coating (41) made of a heat-insulating material. The invention further relates to a method for producing a polymer laminate and to a method for joining prefabricated polymer components to each other.

Claims

1. Plate heat exchanger (10) having a plate heat exchanger block (11) which has a plurality of partitions (4, 5) which are arranged parallel to one another and form a plurality of heat exchange passages (1a, 1b) for fluids which are to be brought into indirect heat exchange with one another, wherein the heat exchange passages (1a, 1b) are delimited by lateral strips (8), and wherein a heat-conducting element (2, 3) is arranged between adjacent partitions (4, 5), and wherein the heat exchange passages (1a, 1b) each have an inlet (9) for inflow of a fluid and an outlet (19) for outflow of the fluid, characterized in that a plurality of partitions (4, 5) and/or a plurality of heat-conducting elements (2, 3) each have a coating (41) of a heat-insulating material.

2. Plate heat exchanger according to claim 1, characterized in that the partition (4, 5) having the coating (41) and/or that the heat-conducting element (2, 3) having the coating (41) has a first section (A1) arranged on the inlet (9) and a second section (A2) connected to the first section (A1), wherein the second section (A2) is further away from the inlet (9) than the first section (A1), and wherein the first section (A1) has the coating (41), and wherein the second section (A2) has no heat-insulating coating.

3. Plate heat exchanger according to claim 1, characterized in that the plate heat exchanger block (11) has at least first heat exchange passages (1a) for receiving a first fluid (B) and second heat exchange passages (1b) for receiving a second fluid (A), wherein the first heat exchange passages (1a) each have a coating (41) of the heat-insulating material, and wherein the second heat exchange passages (1b) have no coating of the heat-insulating material.

4. Plate heat exchanger according to claim 1, characterized in that the heat-insulating material is one of the following materials or has one of the following materials: a plastic, a polymer, a ceramic.

5. Plate heat exchanger according to claim 1, characterized in that the heat-insulating material has a thermal conductivity coefficient of less than 5 W/mKin particular, less than 1 W/mK.

6. Plate heat exchanger according to claim 1, characterized in that the respective coating (41) has a thickness (D1) of less than or equal to 0.2 mm.

7. Plate heat exchanger according to claim 1, characterized in that, for introducing fluids (B) via the inlets (9) of the first heat exchange passages (1a) and via the inlets (9) of the second heat exchange passages (1b), a collector (7) having a nozzle (6) is attached in each case.

8. Plate heat exchanger according to claim 7, characterized in that the collector (7) and/or the nozzle (6) of the first heat exchange passages (1a) has a coating (41) of the heat-insulating material.

9. Plate heat exchanger according to claim 1, characterized in that the respective heat-conducting element (2, 3) has a corrugated structure with alternating foot sections (12) and head sections (14), wherein the respective foot section (12) is connected via a web (13) to an adjacent head section (14).

10. Method for the production of a plate heat exchanger according to claim 1, wherein a flowable material, which, in the hardened state, forms a heat-insulating material, is introduced into heat exchange passages (1a) of the plate heat exchanger block (11), the partitions and/or heat-conducting elements (2, 3) and/or lateral strips (8) of which are to receive the coating (41), wherein the material is cured so as to form the coatings (41).

11. Method according to claim 10, characterized in that the plate heat exchanger block (11) is immersed, at least in sections, in the flowable material in order to introduce the flowable material into the corresponding heat exchange passages (1).

12. Method for operating a plate heat exchanger according to claim 1, wherein at least one first fluid (B) and one second fluid (A) are introduced into at least one heat exchange passage (1a, 1b) of the plate heat exchanger so that the fluids (B, A) can exchange heat.

13. Method according to claim 12, wherein the first fluid (B) is introduced into the at least one first heat exchange passage (1a), and the second fluid (A) is introduced into the at least one second heat exchange passage (1b).

14. Method according to claim 12, wherein, when the plate heat exchanger is started up, the first fluid (B) is introduced into the at least one first heat exchange passage (1a) before the second fluid (A) is introduced into the at least one second heat exchange passage (1b).

15. Method according to claim 12, wherein the first fluid (B) is introduced into the at least one first heat exchange passage (1a) via the nozzle (7) and collector (6) which is arranged above the inlet (9) of the at least one first heat exchange passage (1a).

16. Method according to claim 12, wherein the at least one first fluid (B), which is introduced into the plate heat exchanger prior to all other fluids when the plate heat exchanger is started up, has a temperature which differs by a temperature differential from a temperature of the plate heat exchanger prior to startup.

Description

[0055] Further features and advantages of the present invention shall be described in the following figure descriptions of exemplary embodiments of the invention, with reference to the figures. Shown are:

[0056] FIG. 1 a perspectival illustration of a plate heat exchanger according to the invention.

[0057] FIG. 2 a detail from a cross-section through the plate heat exchanger of FIG. 1 along the sectional plane S-S shown in FIG. 1.

[0058] FIG. 1 shows a plate heat exchanger 10 according to the invention, which has a plurality of partitions in the form of separating plates 4 which are arranged parallel to one another and form a plurality of heat exchange passages, e.g., 1a, 1b, for the fluids A, B, C, D, E which are to be brought into indirect heat exchange with one another. The heat exchange between the fluids participating in the heat exchange takes place between adjacent heat exchange passages 1a, 1b, wherein the heat exchange passages 1a, 1b, and thus the fluids, are separated from one another by the separating plates 4.

[0059] Heat exchange takes place by means of heat transfer via the separating plates 4 and via the heat-conducting elements 2, 3, which are arranged between the separating plates 4 and are also referred to as fins 2, 3. The fins 2 shown in FIG. 1 also serve to distribute the fluids evenly over the respective heat exchange passage 1a, 1b.

[0060] The heat exchange passages 1a, 1b are delimited by lateral strips 8, also referred to below as sidebars 8, in the form of sheet metal strips 8 which are, in particular, arranged flush with the edge of the separating plates 4. In particular, the heat exchange passages 1a, 1b are closed off by the sidebars 8 to the outside, i.e., to the surroundings of the heat exchanger 10.

[0061] The preferably corrugated fins 2, 3 are arranged within the heat exchange passages 1a, 1b, i.e., between two partitions 4 each, wherein a cross-section of a fin 3 is shown in a detail in FIG. 2.

[0062] Accordingly, the fins 3 each have a corrugated structure with alternating foot sections 12, hereinafter also referred to as valleys 12, and head sections 14, hereinafter also referred to as peaks 14, wherein the valleys 12 and peaks 14 are arranged parallel to each other. A valley 12 is connected to an adjacent peak 14 via an, in particular, vertically-running web 13 of the relevant fin 3 so that said corrugated structure results. The corrugated structure, in the transition from valleys 12 or peaks 14 to the respective webs 13, can be formed so as to be rounded. However, it can also have a rectangular or stepped shape. Flow channels 40 for guiding the relevant fluid in the respective heat exchange passage 1a, 1b are formed by the corrugated structure, together with the partitions 4 on both sides.

[0063] The peaks 14 and valleys 12 of the respective fin 3 are integrally connected to the respectively adjacent separating plates 4preferably by soldered joints. The fluids participating in the heat exchange are thus in direct thermal contact with the corrugated structures 3 so that the heat transfer is ensured by the thermal contact between the peaks 14 or valleys 12 and separating plates 4, and thus by thermal conduction. In order to optimize the heat transfer, the orientation of the corrugated structure 3 within the heat exchange passages 1a, 1b is selected as a function of the application in such a way that an equal-, cross-, counter-, or cross-counter-flow between adjacent passages 1a, 1b is made possible.

[0064] The plate heat exchanger 10 furthermore has inlets 9 to the heat exchange passages 1a, 1b (wherein only an inlet 9 to a second heat exchange passage 1b is shown in FIG. 1 for the sake of clarity), which are provided here by way of example at the ends of the plate heat exchanger 10 (inlets at a central section are also possible), wherein the fluids A, B, C, D, E can be introduced into the heat exchange passages 1a, 1b or discharged therefrom via the inlets 9. In the region of these inlets 9, the individual heat exchange passages 1a, 1b can have fins in the form of the distribution fins 2 which distribute the respective fluid to the channels of a fin 3 of the relevant heat exchange passage 1a, 1 b. However, distribution fins 2 are not absolutely necessary. A fluid A, B, C, D, E can thus be introduced via an inlet 9 of the plate heat exchanger block 11 into the assigned heat exchange passage 1a, 1b and discharged again from the relevant heat exchange passage 1a, 1b through a further opening 19an outlet 19.

[0065] The separating plates 4, fins 3, and sidebars 8 and, optionally, further components (for example, the distribution fins 2 shown) are, for example, connected to one another by brazing. For this purpose, the components, such as heating surface elements (fins) 3, separating plates 4, distribution fins 2, cover plates 5, and sidebars 8, are partially provided with solder and are stacked on top of each other in one block, and are subsequently brazed in a furnace to form a heat exchanger block 11.

[0066] For supplying and discharging the heat-exchanging fluids A, B, C, D, E, preferably semi-cylindrical collectors 7 (or headers) are welded on above the inlets 9 and outlets 19, respectively. Furthermore, a cylindrical nozzle 6 is preferably welded to each collector 7. The nozzles 6 serve to connect a supply or discharge pipeline to the respective collector 7.

[0067] As already explained above, in the case of plate heat exchangers of the type shown in FIG. 1, there is, basically, the problem that, during startup or restart, the flows introduced into the plate heat exchanger have a distinct temperature difference compared to the downtime-related temperature of the block 11. The elongations caused thereby and the stresses induced therewith can damage the plate heat exchanger. A downtime-related temperature of the block 11 results when the temperatures of the hot and of the cold ends of the block 11 approximate one another by heat transfer due to the stoppage of the process flows or fluids, resulting in a homogeneous temperature of the fluids and components in the plate heat exchanger.

[0068] According to the invention, it is therefore provided that one or more partitions 4, 5 and/or one or more heat-conducting elements 2, 3 and/or one or more lateral strips 8 each have a coating 41 of a heat-insulating material, which is applied to the respective partition 4, 5 or the respective heat-conducting element 2, 3.

[0069] Examples of suitable heat-insulating materials are disclosed herein. The base material is, in particular, an aluminum alloy (for example, of type 3003). Other suitable aluminum alloys/materials are also conceivable.

[0070] The heat-insulating coating 41 is preferably applied to the partitions 4 and heat-conducting elements (fins) 2, 3 and, optionally, the sidebars 8 in such a way that the flow channels 40 are coated without gaps with the heat-insulating coating 41, preferably in at least one first section A1 of the heat exchange passages 1a (cf. detail of FIG. 1).

[0071] In particular, it can be provided according to one embodiment that only a certain region or a first section A1 of the partitions 4, 5 and the heat-conducting elements 2, 3 and/or lateral strips 8 or the flow channels 40 or the heat exchange passages 1a, 1b has a heat-insulating coating 41. This first section A1 can also mergefor example, along the transition plane U indicated by a dashed line in FIG. 1into a second section A2 of the partitions 4, 5 or heat-conducting elements 2, 3 or lateral strips 8 which, for example, is not provided with a coating 41 according to the invention. Thus, in this second section A2, the inner sides of the flow channels 40 cannot have a heat-insulating coating.

[0072] In this case, the first section A1 preferably adjoins inlets 9 for first heat exchange passages 1a via which a first fluid B is introduced into the block 11 during startupin particular, restartprior to other fluids (for example, prior to a second fluid A). Furthermore, such a coating 41 can also be provided on the collector 7 and/or nozzle 6 via which the first fluid B is introduced into the inlets 9.

LIST OF REFERENCE SIGNS

[0073]

TABLE-US-00001 1a First heat exchange passages 1b Second heat exchange passages 2, 3 Heat-conducting element 4 Partitions 5 Cover walls 6 Nozzle 7 Collector 7a Inner side 7b Edge 8 Sidebars, lateral strips 9 Inlets to the passages 10 Plate heat exchanger 11 Plate heat exchanger block 12 Valley or foot section 13 Web 14 Peak or head section 19 Outlets from the passages 40 Flow channel 41 Coating A1 First section A2 Second section U Transition D1 Coating thickness D2 Partition thickness without coating 41 A, B, C, D, E Fluid I Interior