PLATE HEAT EXCHANGERS AND METHOD

Description

[0001] The invention relates to a plate heat exchanger and a method for operating such a plate heat exchanger.

[0002] A plate heat exchanger is constructed from alternating heating surface elements, specifically so-called fins or heat transfer fins, and separating plates. The heating surface elements are made of corrugated or ribbed aluminum sheets, whereas the separating plates can be made of smooth aluminum sheets. With the help of the heating surface elements and separating plates, the plate heat exchanger forms a multitude of parallel heat transfer passages through which process media can flow and indirectly transfer heat to process media conveyed in adjacent heat transfer passages.

[0003] Leaks in the plate heat exchanger typically require a shutdown. Unplanned downtime, repair, or replacement results in higher costs compared to a planned shutdown. Therefore, early leak detection, which allows for timely planning of the shutdown, is desirable.

[0004] EP 2 244 046 A2 describes a plate heat exchanger constructed from the aforementioned heat transfer elements and separating plates, which are arranged alternately. The separating plates and the heat transfer elements form layers of the plate heat exchanger. Two edge layers, each constructed from two heat transfer elements and separating plates arranged between them, are connected to an analysis unit that enables leak detection. A separating plate is provided between each of the two end layers, which serves as a sensor plate for detecting the leak. US 2010263823 also discloses a plate heat exchanger with an analysis unit that enables leak detection.

[0005] Against this background, one object of the present invention is to provide an improved plate heat exchanger.

[0006] Accordingly, a plate heat exchanger is proposed. The plate heat exchanger comprises an active region through which the process media can flow during operation of the plate heat exchanger for heat exchange between different process media; an inactive void layer that is in fluid communication with the surroundings of the plate heat exchanger; an inactive leak detection layer arranged between the active region and the void layer, wherein the leak detection layer is separated from the active region by a separating plate; and an analysis unit for the chemical analysis of process medium penetrating from the active region into the leak detection layer due to a leak at or in the separating plate, in order to detect the leak.

[0007] Because the analysis unit is configured to detect a leak in or on the separating plate provided between the leak detection layer and the active area, it is unnecessary to also equip the empty layer with such an analysis unit. This allows for a simplified design.

[0008] The plate heat exchanger is, in particular, a so-called Plate Fin Heat Exchanger (PFHE), or can be referred to as such. The plate heat exchanger is constructed from a plurality of alternating heating surface elements and separating plates. In each case, a separating plate is arranged between two heating surface elements, and a heating surface element is arranged between two separating plates. The heating surface elements and the separating plates are thus stacked on top of one another and form a heat exchanger block of the plate heat exchanger. The heating surface elements are so-called fins, in particular so-called heat transfer fins, or can be referred to as fins. The heating surface elements can be designed as corrugated or ribbed sheets, for example, as aluminum sheets. The separating plates are separating plates, or can be referred to as separating plates. The separating plates can also be made of aluminum.The number of heating surface elements and the number of separating plates is arbitrary.

[0009] The plate heat exchanger or the aforementioned heat exchanger block preferably has a cuboid geometry with a width direction or x-direction, a height direction or y-direction, and a depth direction or z-direction. In the height direction, the heat exchanger block preferably has a larger dimension than in the width direction and the depth direction, resulting in an elongated cuboid geometry of the heat exchanger block. The heating surface elements and the separating plates can be arranged side by side in the depth direction or stacked one above the other in the height direction. The plate heat exchanger differs from the heat exchanger block in that the analysis unit is part of the plate heat exchanger, but preferably not part of the heat exchanger block.

[0010] The heating surface elements are preferably enclosed by edge strips, in particular aluminum edge strips, which are also part of the heat exchanger block. The edge strips are soldered to the separating plates and / or the heating surface elements. The edge strips can form a frame surrounding the respective heating surface element. The heat exchanger block can have cover plates that close off the heat exchanger block vertically at the top and bottom. The cover plates can be external separating plates. The cover plates can be soldered to the outermost heating surface elements. Alternatively, separating plates can also be provided between the cover plates and the outermost heating surface elements. The cover plates preferably differ from the separating plates only in their wall thickness or thickness. In contrast to the separating plates, the cover plates preferably do not have any solder plating.

[0011] The plate heat exchanger can be part of a process plant. The process plant can be, for example, a plant for air separation, for the production of liquefied natural gas (LNG), a plant used in the petrochemical industry, or the like. The process plant can comprise a plurality of such plate heat exchangers. Accordingly, a process plant with such a plate heat exchanger is also proposed.

[0012] In the context of the active zone, "active" specifically means that the process media flow through it during operation of the plate heat exchanger, whereby heat exchange occurs between different process media. The heat exchange occurs through the separating plates. The active zone comprises a plurality of alternating separating plates and heating surface elements. The active zone is preferably structurally identical to the empty zone and the leak detection zone. Unlike the empty zone and the leak detection zone, the active zone, or rather the heat transfer passages of the active zone, are flowed through by the process media. In contrast, the leak detection zone and the empty zone are not flowed through by the process media during operation of the plate heat exchanger. The empty zone can also be referred to as a dummy layer.

[0013] "Inactive" in the context of the empty layer and the leak detection layer means that the process media cannot flow through them or are not flowing through them. However, this does not preclude the possibility that, in the event of a leak, some of the process media may also flow into or through the leak detection layer. However, in the event of no leak, the leak detection layer is free of process media.

[0014] The empty layer is in fluid communication with the environment or an atmosphere. Suitable openings or apertures can be provided for this purpose, connecting the empty layer to the environment. The fact that the empty layer is "in fluid communication" with the environment means, in particular, that a fluid, for example, air, can flow from the empty layer into the environment and back. The empty layer is thus pressure-free or pressureless. "Pressure-free" or "pressureless" is understood, in particular, to mean that ambient pressure prevails in the empty layer. In particular, exactly one leak detection layer is provided between the active region and the empty layer. The separating plate can be part of the leak detection layer. However, the separating layer can also be part of the active region. Furthermore, the separating plate can also be assigned to both the leak detection layer and the active region.

[0015] The analysis unit is designed to detect components of the process media, such as hydrocarbons. This enables reliable leak detection even in the case of very small leaks that only allow the respective process medium to penetrate the detection layer drop by drop. This makes it possible to detect leaks before they become critical to the operation of the plate heat exchanger. Cracks or leaks in such a heat exchanger block typically develop very slowly, gradually increasing in size. Therefore, it is expected that a leakage volume flow of the process medium flowing into the leak detection layer can be directed to a collection area for a certain period of time while the plate heat exchanger can continue to operate.

[0016] During this time, a targeted shutdown, replacement, and / or repair of the plate heat exchanger or heat exchanger block can be prepared. The analysis unit can, for example, be a mass spectrometer or include a mass spectrometer. The leak is then detected by the analysis unit's ability to detect chemical components in the process media. If this analysis is positive—for example, if hydrocarbons are detected—an alarm can be triggered. The alarm can be visual or audible.

[0017] According to one embodiment, exactly one leak detection layer is arranged between the active region and the empty layer.

[0018] The leak detection layer located between the active area and the empty layer can be referred to as the first leak detection layer. In addition to the first detection layer, the plate heat exchanger can have a second leak detection layer or any desired additional leak detection layers.

[0019] According to a further embodiment, the leak detection layer comprises the separating plate, a further separating plate which delimits the leak detection layer from the empty layer, and a heating surface element which is arranged between the two separating plates.

[0020] The two separating plates can be assigned to the leak detection layer. In this case, the two separating plates and the heating surface element form the leak detection layer. The fact that the additional separating plate "delimits" the leak detection layer from the empty layer means, in this case, in particular, that the separating plate arranged between the leak detection layer and the empty layer is fluid-tight, so that the leak detection layer is separated from the empty layer in a fluid-tight manner.

[0021] According to a further embodiment, the leak detection layer is pressureless during operation of the plate heat exchanger.

[0022] As previously mentioned, "pressureless" specifically means that ambient pressure prevails in the leak detection layer. Alternatively, the pressure in the leak detection layer can be slightly higher or lower than ambient pressure. However, for chemical analysis using the analysis unit, pressureless operation of the leak detection layer is sufficient.

[0023] According to a further embodiment, the plate heat exchanger further comprises a heat exchanger block having the active region, the empty layer and the leak detection layer, wherein the analysis unit is in fluid communication with the leak detection layer.

[0024] The leak detection layer is thus integrated into the heat exchanger block or plate heat exchanger. The fact that the analysis unit is "in fluid communication" with the leak detection layer means, in this case, that the process medium penetrating the leak detection layer can flow from the leak detection layer to the analysis unit.

[0025] According to a further embodiment, the analysis unit is arranged outside the heat exchanger block.

[0026] The analysis unit can be physically separated from the heat exchanger block. However, this is not mandatory. The analysis unit can also be mounted directly on the heat exchanger block. However, the analysis unit is preferably not part of the heat exchanger block, but rather part of the plate heat exchanger. Multiple analysis units can be provided.

[0027] According to a further embodiment, the analysis unit is in fluid communication with the leak detection layer by means of a line leading away from the leak detection layer and a collecting line into which the line opens.

[0028] If multiple leak detection layers are planned, each leak detection layer is assigned a line. The lines of all leak detection layers flow into the common collecting line, which is fluidically connected to the analysis unit. This means that the analysis unit can be assigned to multiple leak detection layers. Each leak detection layer can also be assigned its own analysis unit.

[0029] According to a further embodiment, the plate heat exchanger further comprises an overpressure protection unit which is in fluid communication with the leak detection layer.

[0030] The overpressure protection unit can be or comprise, for example, a pressure relief valve or a bursting membrane. The overpressure protection unit is connected in particular to the aforementioned manifold. The overpressure protection unit can prevent the leak detection layer from being loaded beyond a design pressure. Bursting of the leak detection layer is thereby reliably prevented. The leak detection layer and the analysis unit form a leak detection device of the plate heat exchanger. The leak detection device can comprise the overpressure protection unit.

[0031] According to a further embodiment, the analysis unit and the overpressure protection unit are connected in parallel.

[0032] For this purpose, the collecting line can branch upstream of the analysis unit and the overpressure protection unit and lead to both the analysis unit and the overpressure protection unit. "Connected in parallel" in this case means that the process medium that has penetrated the leak detection layer is fed simultaneously to both the analysis unit and the overpressure protection unit, rather than passing through the analysis unit and the overpressure protection unit sequentially.

[0033] According to a further embodiment, the plate heat exchanger further comprises a cover plate facing the environment, wherein the void layer is arranged between the cover plate and the leak detection layer.

[0034] A separating plate can be provided between the void layer and the cover plate. The separating plate can be part of the void layer. However, this separating plate is not mandatory. Alternatively, the heating surface element of the void layer can be connected directly to the cover plate. As previously mentioned, the cover plates preferably differ from the separating plates only in their wall thickness. In contrast to the separating plates, the cover plates preferably do not have any solder plating. The plate heat exchanger preferably comprises two cover plates, which, as previously mentioned, can be provided at the top and bottom of the heat exchanger block, viewed along the vertical direction.

[0035] According to a further embodiment, the plate heat exchanger further comprises a first heat exchanger block module with a first cover plate and a second cover plate and a second heat exchanger block module with a first cover plate and a second cover plate, wherein the first heat exchanger block module is connected at its first cover plate to the second cover plate of the second heat exchanger block module.

[0036] In principle, the plate heat exchanger can comprise any number of such heat exchanger block modules. Viewed vertically, the heat exchanger block modules can be placed one on top of the other. Each heat exchanger block module has two such cover plates on its outside. For example, the first heat exchanger block module is welded to the second cover plate of the second heat exchanger block module at its first cover plate or connected in another way.

[0037] According to a further embodiment, the plate heat exchanger further comprises a further inactive leak detection layer arranged between the active region and the first cover plate of the first heat exchanger block module and / or between the active region and the second cover plate of the second heat exchanger block module.

[0038] The additional leak detection layer is preferably structurally identical to the aforementioned first leak detection layer. The additional leak detection layer can also be referred to as a second leak detection layer. Accordingly, each heat exchanger block module can be assigned a first leak detection layer, which is arranged between the active region and the empty layer, and a second leak detection layer, which is arranged between the active region and the respective cover plate. Both the first heat exchanger block module and the second heat exchanger block module can each have a first leak detection layer and a second leak detection layer. The second leak detection layer differs from the first leak detection layer in that the second leak detection layer directly adjoins the cover plate and, in contrast to the first leak detection layer, no empty layer is arranged between the cover plate and the second leak detection layer.In principle, the leak detection layer(s) can be arranged at any position within the heat exchanger block or the heat exchanger. In particular, one or more leak detection layers can be placed within the active area.

[0039] According to a further embodiment, the plate heat exchanger comprises a collecting region arranged downstream of the analysis unit for collecting the process medium penetrating from the active region into the leak detection layer.

[0040] The process medium preferably flows through the analysis unit into the collection area. The collection area can be, for example, a storage tank or the like. Using the collection area, the process medium that has penetrated the leak detection layer can be stored until a planned shutdown of the plate heat exchanger can be carried out, for example, for repair purposes. Alternatively, the collection area can also be suitable for thermally recycling, i.e., incinerating, the process medium that has penetrated the leak detection layer. In particular, the process medium can be fed into a flare system.

[0041] Furthermore, a method for operating such a plate heat exchanger is proposed. The plate heat exchanger comprises an active region, an inactive empty layer that is in fluid communication with the surroundings of the plate heat exchanger, an inactive leak detection layer arranged between the active region and the empty layer, wherein the leak detection layer is separated from the active region by means of a separating plate, and an analysis unit. The method comprises the following steps: a) flowing different process media through the active region, whereby heat exchange takes place between the process media, and b) chemically analyzing process medium penetrating from the active region into the leak detection layer due to a leak at or in the separating plate using the analysis unit, thereby detecting the leak.

[0042] As previously mentioned, the active region comprises a plurality of stacked heating surface elements and separating plates. This creates heat transfer passages. In adjacent heat transfer passages, heat exchange between the process media can take place via the respective separating plate. The heat exchange can take place in cocurrent, crosscurrent, and / or countercurrent. Step b) is preferably carried out continuously. This means, in particular, that the analysis unit is always in operation to detect leaks. Alternatively, the analysis unit can also be activated only after a predetermined time interval. During chemical analysis, components of the process media, for example hydrocarbons, can be detected by the analysis unit. As soon as the analysis unit detects or can detect these components, it can be assumed that a leak is present.

[0043] According to one embodiment, the leak detection layer is kept pressureless during step b).

[0044] As previously mentioned, this means, in particular, that the leak detection layer is operated at ambient pressure. Accordingly, the empty layer can also be operated at ambient pressure and is thus preferably depressurized. The leak detection layer can be protected against the penetration of ambient components backward into the leak detection layer, which could otherwise trigger a false alarm in the analysis unit. This can be achieved, for example, by continuously purging with an inert gas, a check valve, a defined low point near an outlet from the leak detection layer with a liquid seal, or the like.

[0045] The embodiments and explanations explained for the plate heat exchanger apply accordingly to the process and vice versa.

[0046] "One" in this case is not necessarily limited to a single element. Rather, multiple elements, such as two, three, or more, may be included. Any other counting term used here should not be understood as implying a limitation to the exact number of elements mentioned. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

[0047] Further possible implementations of the plate heat exchanger and / or the method also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the plate heat exchanger and / or the method.

[0048] Further advantageous embodiments and aspects of the plate heat exchanger and / or the method are the subject of the dependent claims and the exemplary embodiments of the plate heat exchanger and / or the method described below. The plate heat exchanger and / or the method are explained in more detail below using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a schematic perspective view of an embodiment of a plate heat exchanger; Fig. 2 shows a schematic sectional view of an embodiment of a heat exchanger block for the plate heat exchanger according to Fig. 1 ; and Fig. 3 shows a schematic block diagram of an embodiment of a method for operating the plate heat exchanger according to Fig. 1 .

[0049] In the figures, identical or functionally equivalent elements have been given the same reference numerals unless otherwise stated.

[0050] The Fig. 1 shows a schematic perspective view of an embodiment of a plate heat exchanger or plate heat exchanger 1. The Fig. 2 shows a schematic sectional view of an embodiment of a heat exchanger block 2 for the plate heat exchanger 1 according to Fig. 1 . The following refers to the Fig. 1 and 2 referred to at the same time.

[0051] With the help of the Fig. 1The plate heat exchanger 1 shown here enables heat exchange between several different process media A to E. The process media A to E can also be referred to as fluids or media. The plate heat exchanger 1 is, in particular, a plate fin heat exchanger (PFHE) or can be referred to as such. The plate heat exchanger 1 is preferably constructed from components made of aluminum that are soldered, in particular brazed, to one another. The plate heat exchanger 1 can therefore also be referred to as a brazed aluminum plate fin heat exchanger.

[0052] The heat exchanger block 2 is cuboid-shaped or block-shaped and comprises a plurality of passages or heating surface elements 3 as well as a plurality of separating plates 4. The heating surface elements 3 are so-called fins, in particular so-called heat transfer fins, or can be referred to as fins. The heating surface elements 3 can be designed as corrugated or ribbed sheets, for example, as aluminum sheets. The separating plates 4 are separating plates or can be referred to as separating plates. The separating plates 4 can also be made of aluminum. The number of heating surface elements 3 and the number of separating plates 4 is arbitrary.

[0053] The heat exchanger block 2 is assigned a coordinate system with a first spatial direction or width direction x, a second spatial direction or height direction y, and a third spatial direction or depth direction z. The directions x, y, and z are oriented perpendicular to each other. The width direction x can also be referred to as the x-direction of the heat exchanger block 2. The height direction y can also be referred to as the y-direction of the heat exchanger block 2. The depth direction z can also be referred to as the z-direction of the heat exchanger block 2.

[0054] The heating surface elements 3 and the separating plates 4 are arranged alternately. This means that a separating plate 4 is positioned between each two heating surface elements 3, and a heating surface element 3 is positioned between each two separating plates 4. The heating surface elements 3 and the separating plates 4 can be connected to one another by a material bond. In material bonded connections, the connecting partners are held together by atomic or molecular forces. Material bonded connections are non-detachable connections that can only be separated by destroying the connecting elements and / or the connecting partners.

[0055] In particular, the heating surface elements 3 and the separating plates 4 can be soldered to one another, in particular hard-soldered.

[0056] The heat exchanger block 2 further comprises cover plates 5, 6, between which the plurality of heating surface elements 3 and the plurality of separating plates 4 are arranged. A first cover plate 5 and a second cover plate 6 are provided. The cover plates 5, 6 can be constructed identically to the separating plates 4. However, the cover plates 5, 6 can differ from the separating plates 4 in their thickness or wall thickness. In contrast to the separating plates 4, the cover plates 5, 6 preferably do not have any solder plating. The cover plates 5, 6 are positioned on the outside on a respective outermost heating surface element 3 and enclose the heat exchanger block 2 in the orientation of the Fig. 1 forwards and backwards.

[0057] Furthermore, the heat exchanger block 2 comprises so-called sidebars or edge strips 7, 8, which laterally delimit the heating surface elements 3. The edge strips 7, 8 can be integrally connected to the separating plates 4 and / or the heating surface elements 3, for example, by soldering, in particular by brazing. The aforementioned components of the heat exchanger block 2 are made, for example, of the material 3003 (AlMn1Cu).

[0058] With the help of the heating surface elements 3 and the separating plates 4, the plate heat exchanger 1 forms a plurality of parallel heat transfer passages in which the process media A to E can flow. This allows heat to be transferred indirectly between process media A to E carried in adjacent heat transfer passages. The individual heat transfer passages can be supplied with a respective process medium A to E using connection devices 9 to 18 by supplying the respective process medium A to E to the plate heat exchanger 1, or the respective process medium A to E can be led away from the plate heat exchanger 1 using such a connection device 9 to 18. The connection devices 9 to 18 are so-called headers or can be referred to as such. Depending on their function, the connection devices 9 to 18 can also be referred to as distributors or collectors.

[0059] For example, the connection devices 11, 13, 15 are suitable for supplying the process media A, B, D to the plate heat exchanger 1, and the connection devices 9, 10, 12, 14 are suitable for discharging the process media A, C, D, E from the plate heat exchanger 1.

[0060] Each connection device 9 to 18 is assigned a connection piece 19 to 25, with the aid of which the respective connection device 9 to 18 can be supplied with the corresponding process medium A to E or the corresponding process medium A to E can be removed from the connection device 9 to 18. The connection devices 9 to 18 are integrally connected to the heat exchanger block 2. In particular, the connection devices 9 to 18 are welded to the heat exchanger block 2. The connection devices 9 to 18 can also be soldered to the heat exchanger block 2.

[0061] The plate heat exchanger 1 can be part of a process plant 26. The process plant 26 can be, for example, a plant for air separation, for the production of liquefied natural gas (LNG), a plant used in the petrochemical industry, or the like. The process plant 26 can comprise a plurality of such plate heat exchangers 1.

[0062] As previously mentioned, the components of the plate heat exchanger 1 are preferably made of an aluminum alloy. For strength reasons, a high-magnesium aluminum alloy, such as material 5083 (AlMg4.5Mn) or a comparable material, is preferably used for the connecting devices 9 to 18. Such high-magnesium aluminum alloys have a magnesium content of approximately 4 to 5%. Such aluminum alloys exhibit high strength.

[0063] To manufacture the heat exchanger block 2, its individual parts, namely the heating surface elements 3, the separating plates 4, the cover plates 5, 6, and the edge strips 7, 8, are soldered, in particular hard-soldered, together in a vacuum in a soldering furnace using an aluminum solder. The aluminum solder can be applied to the separating plates 4 on one or both sides as a solder layer, in particular as a solder plating.

[0064] Leaks in the heat exchanger block 2 generally require shutting down the plate heat exchanger 1 or the entire process plant 26. Unplanned downtime, repair, or replacement result in higher costs compared to a planned shutdown. Therefore, early leak detection, which enables early planning of the shutdown, is desirable. For this purpose, the plate heat exchanger 1 has a leak detection device 27, which will be explained later.

[0065] The heat exchanger block 2 has a modular design and comprises a first heat exchanger block module 28 and a second heat exchanger block module 29. Viewed along the vertical direction y, the heat exchanger block modules 28, 29 are arranged one above the other or stacked. The heat exchanger block modules 28, 29 can be firmly connected to one another, for example, by soldering.

[0066] Each heat exchanger block module 28, 29 comprises two cover plates 5, 6 as previously mentioned. The cover plate 5 of the first heat exchanger block module 28 rests against the cover plate 6 of the second heat exchanger block module 29. For example, the cover plate 5 of the first heat exchanger block module 28 and the cover plate 6 of the second heat exchanger block module 29 are firmly connected to one another, in particular welded to one another or connected to one another in another way.

[0067] A plurality of heating surface elements 3 and separating plates 4, as previously mentioned, are arranged alternately between the cover plates 5, 6 of each heat exchanger block module 28, 29. The heat exchanger block modules 28, 29 are closed off at the edges by edge strips 7, 8.

[0068] The cover plate 6 of the first heat exchanger block module 28 and the cover plate 5 of the second heat exchanger block module 29 are located on the outside. In the orientation of the Fig. 3 A dummy layer 30 is provided beneath the cover plate 6 of the first heat exchanger block module 28. The dummy layer 30 comprises a heating surface element 3 as mentioned above, which is arranged between two separating plates 4.

[0069] No process media A to E flow through the empty layer 30. The empty layer 30 is therefore inactive. "Inactive" in the context of the empty layer 30 means that it is not subject to or capable of flow by the process media A to E. The empty layer 30 is open to the atmosphere or environment 31 surrounding the heat exchanger block 2. The empty layer 30 is thus depressurized, or ambient pressure prevails in the empty layer 30.

[0070] In the orientation of the Fig. 3 A dummy layer 32 is provided above the cover plate 5 of the second heat exchanger block module 29. The dummy layer 32 is structurally identical to the dummy layer 30. The dummy layer 32 accordingly comprises a heating surface element 3 arranged between two separating plates 4.

[0071] No process medium A to E flows in the empty layer 32 either. The empty layer 32 is therefore also inactive. The empty layer 32 is also open to the environment 31. The empty layer 32 is therefore also pressureless, or ambient pressure prevails in the empty layer 32. However, no empty layer 30, 32 as mentioned above is provided on the mutually facing cover plates 5, 6 of the heat exchanger block modules 28, 29. However, an additional empty layer 30, 32 as mentioned above can be provided on each of the mutually facing cover plates 5, 6 of the heat exchanger block modules 28, 29.

[0072] Each heat exchanger block module 28, 29 has an active area 33, 34. The first heat exchanger block module 28 is assigned the active area 33. The second heat exchanger block module 29 is assigned the active area 34. Each active area 33, 34 comprises a plurality of heat transfer passages formed by the heating surface elements 3 and the separating plates 4. The process media A to E flow through these heat transfer passages.

[0073] "Active" in the context of the active areas 33, 34 means that they are flowed through or can be flowed through by the process media A to E. In contrast, the empty areas 30, 32 are inactive and do not have any flow of the process media A to E. The empty areas 30, 32 are therefore not part of the active areas 33, 34.

[0074] The first heat exchanger block module 28 has a first leak detection layer 35. The first leak detection layer 35 comprises a heating surface element 3 arranged between two separating plates 4. The first leak detection layer 35 is arranged between the empty layer 30 and the active region 33. The first leak detection layer 35 is fluidically separated from the empty layer 30 by means of a separating plate 4. "Fluidically separated" in this context means that fluid exchange between the first leak detection layer 35 and the empty layer 30 is not possible. This aforementioned separating plate 4 can be assigned to the empty layer 30, the first leak detection layer 35, or both the empty layer 30 and the first leak detection layer 35.

[0075] The first leak detection layer 35 is fluidically separated from the active region 33 by a separating plate 4. This aforementioned separating plate 4 can be assigned to the first leak detection layer 35, the active region 33, or both the first leak detection layer 35 and the active region 33.

[0076] The first heat exchanger block module 28 further comprises a second leak detection layer 36. Viewed along the depth direction z, the active region 33 is positioned between the first leak detection layer 35 and the second leak detection layer 36. The second leak detection layer 36 comprises a heating surface element 3 arranged between two separating plates 4. The second leak detection layer 36 is arranged between the cover plate 5 of the first heat exchanger block module 28 and the active region 33.

[0077] The second leak detection layer 36 has a separating plate 4 that is firmly connected, in particular soldered, to the cover plate 5. This aforementioned separating plate 4 can be part of the second leak detection layer 36. The second leak detection layer 36 is arranged between the cover plate 5 and the active region 33. The second leak detection layer 36 is fluidically separated from the active region 33 by a separating plate 4. This aforementioned separating plate 4 can be assigned to the second leak detection layer 36, the active region 33, or both the second leak detection layer 36 and the active region 33. The leak detection layers 35, 36 are not flowed through by the process media A to E. The leak detection layers 35, 36 are therefore "inactive."

[0078] The second heat exchanger block module 29 is preferably constructed identically to the first heat exchanger block module 28. Accordingly, the second heat exchanger block module 29 also has a first leak detection layer 37 and a second leak detection layer 38. The active region 34 is positioned between these two leak detection layers 37, 38. Process media A to E do not flow through the leak detection layers 37, 38 either. Accordingly, the leak detection layers 37, 38 are also inactive. All leak detection layers 35 to 38 are sealed off from the environment 31. However, the leak detection layers 35 to 38 are preferably depressurized.

[0079] Each of the leak detection layers 35 to 38 is assigned a line 39 to 42, which is in fluid communication with the respective leak detection layer 35 to 38. The lines 39 to 42 flow into a common collecting line 43. The collecting line 43 branches off and leads to an analysis unit 44 and an overpressure protection unit 45. The leak detection layers 35 to 38, the lines 39 to 42, the collecting line 43, the analysis unit 44, and the overpressure protection unit 45 together form the leak detection device 27 of the heat exchanger block 2 or the plate heat exchanger 1.

[0080] The analysis unit 44 is configured to detect and identify chemical substances, such as hydrocarbons, contained in the process media A to E. The analysis unit 44 can be a mass spectrometer or can comprise a mass spectrometer. The analysis unit 44 can comprise a computer, a data storage device, or the like. The analysis unit 44 can also be capable of outputting an analysis result. This can be done visually on a screen, for example. Depending on the analysis result, an acoustic and / or visual warning signal can also be output.

[0081] The overpressure protection unit 45 prevents an undesirable pressure buildup in the leak detection layers 35 to 38. The overpressure protection unit 45 can be or comprise a pressure relief valve or a bursting membrane. The overpressure protection unit 45 prevents a pressure increase within the leak detection layers 35 to 38 above a design pressure of the heat exchanger block 2.

[0082] Leak detection layers 35 to 38 are provided in active areas of the heat exchanger block 2 where leaks are most likely to occur. In the present case, this is, for example, an active area where the two heat exchanger block modules 28, 29 are connected to each other, as well as an active area that includes the outer cover plates 5, 6. Temperature-related high mechanical stresses can occur in these aforementioned active areas, which can lead to cracks.

[0083] The two second leak detection layers 36, 38 are provided here for leak detection. Furthermore, the first leak detection layers 35, 37 are provided on the cover plates 5, 6 facing the environment 31. In principle, however, the leak detection layers 35 to 38 can be provided at any location, in particular within the active regions 33, 34. At least one leak detection layer 35 to 38 is provided for leak detection.

[0084] The functionality of the leak detection device 27 is explained below using the first leak detection layer 35 of the first heat exchanger block module 28. However, all explanations regarding the first leak detection layer 35 are applicable accordingly to the other leak detection layers 36 to 38.

[0085] In the event that the separating plate 4 provided between the first detection layer 35 and the active region 33 develops a leak, a portion of the respective process medium A to E flows into the first detection layer 35. It is sufficient if very small amounts of the respective process medium A to E penetrate from the active region 33 into the first detection layer 35. The process medium A to E is then fed via line 39 and the collecting line 43 to the analysis unit 44, which chemically analyzes the process medium A to E.

[0086] The chemical analysis searches for chemical substances, such as hydrocarbons, contained in the process media A to E. If the analysis is positive, i.e., if hydrocarbons are detected, an alarm can be triggered. The analysis unit 44 channels the leaked process media A to E into a suitable collection area 46 or disposes of it so that the process media A to E do not enter the environment 31. The collection area 46 can be a storage tank or the like. Typically, however, the process media A to E are fed into a flare system.

[0087] Cracks in such a heat exchanger block 2 typically develop very slowly and gradually increase in size. Therefore, it is expected that a leakage volume flow of the process medium A to E flowing into the first leak detection layer 35 can be directed to the aforementioned collection area 46 over a certain period of time. During this time, a targeted shutdown, replacement, and / or repair of the plate heat exchanger 1 or the heat exchanger block 2 can be prepared. It is thus possible to detect leaks before they become critical for the operation of the plate heat exchanger 1.

[0088] The Fig. 3 shows a schematic block diagram of an embodiment of a method for operating the plate heat exchanger 1.

[0089] The method comprises a step S1 of flowing the process media A to E through the respective active region 33, 34, wherein a heat exchange is carried out between the process media A to E. In a step S2, process media A to E penetrating from the active region 33, 34 into the leak detection layer 35 to 38 due to a leak at or in the separating plate 4 is chemically analyzed using the analysis unit 44, thereby detecting the leak. Preferably, the leak detection layer 35 to 38 is kept depressurized during step S2.

[0090] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. Reference symbols used

[0091] 1 Plate heat exchanger 2 Heat exchanger block 3 Heating surface element 4 Separator plate 5 Cover plate 6 Cover plate 7 Edge strip 8 Edge strip 9 Connection device 10 Connection device 11 Connection device 12 Connection device 13 Connection device 14 Connection device 15 Connection device 16 Connection device 17 Connection device 18 Connection device 19 Connection piece 20 Connection piece 21 Connection piece 22 Connection piece 23 Connection piece 24 Connection piece 25 Connection piece 26 Process plant 27 Leak detection device 28 Heat exchanger block module 29 Heat exchanger block module 30 Empty position 31 Surroundings 32 Empty position 33 Active area 34 Active area 35 Leak detection position 36 Leak detection position 37 Leak detection position 38Leak detection position 39Line 40Line 41Line 42Line 43Collecting line 44Analysis unit 45Overpressure protection unit 46Collection area AProcess medium BProcess medium CProcess medium DProcess medium EProcess medium S1Step S2Step xWidth direction yHeight direction zDepth direction

Claims

1. Plate heat exchanger (1) comprising an active region (33, 34) through which, for heat exchange between different process media (A - E), the process media (A - R) can flow during operation of the plate heat exchanger (1), an inactive empty layer (30, 32) which is in fluid connection with an environment (31) of the plate heat exchanger (1), an inactive leak detection layer (35, 37) which is arranged between the active region (33, 34) and the empty layer (30, 32), wherein the leak detection layer (35, 37) is separated from the active region (33, 34) by means of a separating plate (4), and an analysis unit (44) for chemically analyzing a process medium (A - E) penetrating from the active region (33, 34) into the leak detection layer (35, 37) due to a leak on or in the separating plate (4), in order to detect the leak.

2. Plate heat exchanger according to claim 1, wherein exactly one leak detection layer (35, 37) is arranged between the active region (33, 34) and the empty layer (30, 32).

3. Plate heat exchanger according to either claim 1 or claim 2, wherein the leak detection layer (35, 37) comprises the separating plate (4), a further separating plate (4) which delimits the leak detection layer (35, 37) with respect to the empty layer (30, 32), and a heating surface element (3) which is arranged between the two separating plates (4).

4. Plate heat exchanger according to any of claims 1 - 3, wherein the leak detection layer (35, 37) is unpressurized during operation of the plate heat exchanger (1).

5. Plate heat exchanger according to any of claims 1 - 4, further comprising a heat exchanger block (2) which has the active region (33, 34), the empty layer (30, 32) and the leak detection layer (35, 37), wherein the analysis unit (44) is in fluid connection with the leak detection layer (35, 37).

6. Plate heat exchanger according to claim 5, wherein the analysis unit (44) is arranged outside the heat exchanger block (2).

7. Plate heat exchanger according to either claim 5 or claim 6, wherein the analysis unit (44) is in fluid connection with the leak detection layer (35, 37) by means of a line (39, 42) leading away from the leak detection layer (35, 37) and a manifold (43) into which the line (39, 42) opens.

8. Plate heat exchanger according to any of claims 1 - 7, further comprising an overpressure protection unit (45) which is in fluid connection with the leak detection layer (35, 37).

9. Plate heat exchanger according to claim 8, wherein the analysis unit (44) and the overpressure protection unit (45) are connected in parallel.

10. Plate heat exchanger according to any of claims 1 - 9, further comprising a cover plate (5, 6) facing the environment (31), wherein the empty layer (30) is arranged between the cover plate (5, 6) and the leak detection layer (35, 37).

11. Plate heat exchanger according to claim 10, further comprising a first heat exchanger block module (28) having a first cover plate (5) and a second cover plate (6) and a second heat exchanger block module (29) having a first cover plate (5) and a second cover plate (6), wherein the first heat exchanger block module (28) is connected at its first cover plate (5) to the second cover plate (6) of the second heat exchanger block module (29).

12. Plate heat exchanger according to claim 11, further comprising a further inactive leak detection layer (36, 38) arranged between the active region (33) and the first cover plate (5) of the first heat exchanger block module (28) and / or between the active region (34) and the second cover plate (5) of the second heat exchanger block module (29).

13. Plate heat exchanger according to any of claims 1 - 12, further comprising a collecting region (46) arranged downstream of the analysis unit (44) for collecting the process medium (A - E) penetrating from the active region (33, 34) into the leak detection layer (35, 37).

14. Method for operating a plate heat exchanger (1) having an active region (33, 34), an inactive empty layer (30, 32) which is in fluid connection with an environment (31) of the plate heat exchanger (1), an inactive leak detection layer (35, 37) which is arranged between the active region (33, 34) and the empty layer (30, 32), wherein the leak detection layer (35, 37) is separated from the active region (33, 34) by means of a separating plate (4), and an analysis unit (44), comprising the following steps: a) a flow (S1) of different process media (A - E) through the active region (33, 34), wherein a heat exchange is carried out between the process media (A - E), and b) a chemical analysis (S2) of the process medium (A - E) penetrating from the active region (33, 34) into the leak detection layer (35, 37) due to a leak on or in the separating plate (4) by means of the analysis unit (44), as a result of which the leak is detected.

15. Method according to claim 14, wherein the leak detection layer (35, 37) is kept unpressurized during step b).