EP4300024A1 - Plate heat exchanger and method - Google Patents

Abstract

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

Description

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

A plate heat exchanger is made up of alternately arranged heating surface elements, in particular 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 the separating plates, the plate heat exchanger forms a large number of parallel heat transfer passages in which process media can flow and indirectly transfer heat to process media guided in adjacent heat transfer passages. Leaks in the plate heat exchanger usually require it to be shut down. Unplanned downtime, repair or replacement results in higher costs compared to a planned shutdown. Therefore, early leak detection that enables timely shutdown planning is desirable.

The EP 2 244 046 A2 describes a plate heat exchanger which is constructed of heat transfer elements and partition plates as mentioned above, which are arranged alternately. The separating plates and the heat transfer elements form layers of the plate heat exchanger. Two edge layers each, which are made up of two heat transfer elements and separating plates arranged between them, are connected to an analysis unit, which enables a leak to be detected. A separating plate is provided between the two end layers, which serves as a sensor plate for detecting the leak.

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

Accordingly, a plate heat exchanger is proposed. The plate heat exchanger includes an active area, which is used during operation of the plate heat exchanger Heat exchange between different process media can be flowed through with the process media, an inactive empty layer which is in fluid communication with an environment of the plate heat exchanger, an inactive leak detection layer which is arranged between the active area and the empty layer, the leak detection layer being separated from the active area using a separating plate is separated, and an analysis unit for the chemical analysis of process medium penetrating from the active area into the leak detection layer due to a leak on or in the separation plate in order to detect the leak.

Because the analysis unit is set up to detect a leak in or on the separating plate provided between the leak detection layer and the active area, it is not necessary to also equip the empty layer with such an analysis unit. This allows a simplified structure to be achieved.

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 made up of a large number of alternately arranged heating surface elements and separating plates. 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 partition plates are partition plates or can be referred to as partition plates. The separating plates can also be made of aluminum. The number of heating surface elements and the number of separating plates is arbitrary.

The plate heat exchanger or the previously mentioned heat exchanger block preferably has a cuboid geometry with a width direction or x-direction, a vertical direction or y-direction and a depth direction or z-direction. In the vertical direction, the heat exchanger block preferably has a larger dimension than in the width direction and the depth direction, so that an elongated cuboid geometry of the heat exchanger block results. The Heating surface elements and the separating plates can be arranged next to one another in the depth direction or stacked one above the other in the vertical 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.

The heating surface elements are preferably framed with the help of 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 the heat exchanger block in the vertical direction up and down. The cover plates can be external partition plates. The cover plates can be soldered to outermost heating surface elements. Alternatively, separating plates can also be provided between the cover plates and the outermost heating surface elements. The cover plates differ from the partition plates preferably only in their wall thickness or thickness. In contrast to the separating plates, the cover plates preferably do not have any solder plating.

The plate heat exchanger can be part of a process engineering system. The process engineering 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 engineering system can include a large number of such plate heat exchangers. Accordingly, a process engineering system with such a plate heat exchanger is also proposed.

In connection with the active area, “active” means in particular that the process media flows through it during operation of the plate heat exchanger, with heat exchange taking place between different process media. The heat exchange takes place through the separating plates. The active area includes a large number of alternately arranged separating plates and heating surface elements. Preferably, the active area does not differ structurally from the empty position and the leak detection position. In contrast to the empty layer and the leak detection layer, the active area or the heat transfer passages of the active area with the process media flows through. In contrast, the leak detection position and the empty position are not flowed through by the process media when the plate heat exchanger is in operation. The empty layer can also be referred to as a dummy layer.

In connection with the empty position and the leak detection position, “inactive” means that the process media cannot or will not flow through them. However, this does not rule out the possibility that in the event of a leak, part of the process medium can also flow into or flow through the leak detection layer. However, in the event that there is no leak, the leak detection layer is free of process media.

The void is in fluid communication with the environment or an atmosphere. For this purpose, suitable openings or breakthroughs can be provided which connect the empty layer with the surroundings. In the present case, the fact that the empty layer is “in fluid connection” 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 position is therefore pressure-free or pressure-free. In the present case, “pressure-free” or “unpressurized” means in particular that ambient pressure prevails in the empty position. In particular, exactly one leak detection position is provided between the active area and the empty position. The separation plate can be part of the leak detection layer. However, the separating layer can also be part of the active area. Furthermore, the separating plate can also be assigned to both the leak detection layer and the active area.

The analysis unit is set up to detect components, such as hydrocarbons, of the process media. This makes it possible to reliably detect the leak even in the case of very small leaks, which only allow the respective process medium to penetrate dropwise into the detection position. It is therefore possible to detect leaks before they become critical for the operation of the plate heat exchanger. As a rule, cracks or leaks in such a heat exchanger block develop very slowly and become increasingly larger. It is therefore to be expected that a leakage volume flow of the process medium flowing into the leak detection layer can be directed to a collecting area over a certain time, while the plate heat exchanger can continue to be operated.

Meanwhile, a targeted shutdown, replacement and/or repair of the plate heat exchanger or the heat exchanger block can be prepared. The analysis unit can be, for example, a mass spectrometer or include a mass spectrometer. The leak is then detected because the analysis unit can detect chemical components of the process media. If this analysis is positive, that is, for example, that hydrocarbons are detected, an alarm can be issued, for example. The alarm can be visual or acoustic.

According to one embodiment, exactly one leak detection layer is arranged between the active area and the empty layer.

The leak detection layer arranged 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 other leak detection layers.

According to a further embodiment, the leak detection layer has 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.

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. In the present case, the fact that the further separating plate “delimits” the leak detection layer from the empty layer means 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.

According to a further embodiment, the leak detection position is depressurized during operation of the plate heat exchanger.

As mentioned above, “unpressurized” is to be understood in particular as meaning that there is ambient pressure in the leak detection position. Alternatively, in the leak detection position There is also a slightly increased or slightly reduced pressure compared to the ambient pressure. However, for chemical analysis using the analysis unit, unpressurized operation of the leak detection layer is sufficient.

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.

The leak detection layer is therefore integrated into the heat exchanger block or into the plate heat exchanger. In the present case, the fact that the analysis unit is “in fluid communication” with the leak detection layer means in particular that the process medium penetrating into the leak detection layer can flow from the leak detection layer to the analysis unit.

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

The analysis unit can be spatially separated from the heat exchanger block. However, this is not absolutely necessary. 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. Several analysis units can be provided.

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

In the event that several leak detection layers are provided, each leak detection layer is assigned a line. The lines of all leak detection layers open into the common collecting line, which is in fluid communication with the analysis unit. This means that the analysis unit can be assigned to several leak detection layers. Each leak detection layer can also be assigned its own analysis unit.

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.

The overpressure protection unit can be or include, for example, an overpressure valve or a bursting membrane. The overpressure protection unit is connected in particular to the aforementioned manifold. The overpressure protection unit can be used to prevent the leak detection layer from being loaded beyond a design pressure. This reliably prevents the leak detection layer from bursting. The leak detection layer and the analysis unit form a leak detection device of the plate heat exchanger. The leak detection device can include the overpressure protection unit.

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

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. In the present case, “connected in parallel” means that the respective process medium that has penetrated into the leak detection position is simultaneously supplied to both the analysis unit and the overpressure protection unit and is not passed through the analysis unit and the overpressure protection unit one after the other.

According to a further embodiment, the plate heat exchanger further comprises a cover plate facing the environment, the empty layer being arranged between the cover plate and the leak detection layer.

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

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.

In principle, the plate heat exchanger can include any number of such heat exchanger block modules. Viewed along the vertical direction, the heat exchanger block modules can be placed on top of each other. Each heat exchanger block module has two such cover plates on the outside. For example, the first heat exchanger block module is welded at its first cover plate to the second cover plate of the second heat exchanger block module or connected in another way.

According to a further embodiment, the plate heat exchanger further comprises a further inactive leak detection layer which is 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.

The further leak detection layer is preferably identical in construction to the previously mentioned first leak detection layer. The further 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 area and the empty layer, and a second leak detection layer, which is arranged between the active area 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 or the leak detection layers can be arranged at any position within the heat exchanger block or the heat exchanger. In particular, a leak detection layer or several leak detection layers can also be placed within the active area.

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

The process medium preferably flows through the analysis unit into the collection area. The collecting area can be, for example, a storage container or the like. With the help of the collecting area, the process medium that has penetrated into the leak detection layer can be stored until a planned shutdown of the plate heat exchanger, for example for repair purposes, can be carried out. Alternatively, the collecting area can also be suitable for thermally utilizing, i.e. burning, the process medium that has penetrated into the leak detection layer. In particular, the process medium can be fed to a flare system.

Furthermore, a method for operating such a plate heat exchanger is proposed. The plate heat exchanger comprises an active area, an inactive empty layer which is in fluid communication with an environment of the plate heat exchanger, an inactive leak detection layer which is arranged between the active area and the empty layer, the leak detection layer being separated from the active area using a separating plate , and a unit of analysis. The method has the following steps: a) flowing different process media through the active area, with a heat exchange being carried out between the process media, and b) chemically analyzing process medium penetrating from the active area into the leak detection layer due to a leak on or in the separating plate with the help of the analysis unit, whereby the leak is detected.

As previously mentioned, the active area has a plurality of stacked heating surface elements and separating plates. This creates heat transfer passages. In the case of adjacent heat transfer passages, the Heat exchange between the process media takes 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 only be activated after a predetermined time interval. During chemical analysis, in particular components of the process media, for example hydrocarbons, can be recognized by the analysis unit. As soon as the analysis unit recognizes or can detect these components, it can be assumed that a leak is present.

According to one embodiment, the leak detection layer is kept depressurized during step b).

As mentioned previously, this means in particular that the leak detection layer is operated under ambient pressure. Accordingly, the empty position can also be operated under ambient pressure and is therefore preferably unpressurized. The leak detection layer can be protected against penetration of components from the environment backwards into the leak detection layer, which could otherwise trigger a false alarm on the analysis unit. This can be done, for example, with the help of continuous flushing with an inert gas, a check valve, a defined low point near an exit from the leak detection layer with a liquid closure or the like.

The embodiments and explanations explained for the plate heat exchanger apply accordingly to the method and vice versa.

In the present case, “on” is not necessarily to be understood as limiting it to exactly one element. Rather, several elements, such as two, three or more, can also be provided. Any other counting word used here should not be understood to mean that there is a limitation to exactly the number of elements mentioned. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

Further possible implementations of the plate heat exchanger and/or the method also include combinations of features or embodiments described previously or below with regard to the exemplary embodiments that are not explicitly mentioned. The expert will also add individual aspects as improvements or additions to the respective basic form of the plate heat exchanger and/or the process.

• Fig. 1 zeigt eine schematische perspektivische Ansicht einer Ausführungsform eines Plattenwärmetauschers;
• Fig. 2 zeigt eine schematische Schnittansicht einer Ausführungsform eines Wärmetauscherblocks für den Plattenwärmetauscher gemäß Fig. 1; und
• Fig. 3 zeigt ein schematisches Blockdiagramm einer Ausführungsform eines Verfahrens zum Betreiben des Plattenwärmetauschers gemäß Fig. 1.

Further advantageous refinements and aspects of the plate heat exchanger and/or the method are the subject of the subclaims 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 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 .

In the figures, identical or functionally identical elements have been given the same reference numbers unless otherwise stated.

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 . Below we will refer to the Fig. 1 and 2 referred to at the same time.

With the help of the in the Fig. 1 Plate heat exchanger 1 shown, heat exchange between several different process media A to E can be realized. The process media A to E can also be used as fluids or media be referred to. 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 that are made of aluminum and soldered, in particular hard-soldered, together. The plate heat exchanger 1 can therefore also be referred to as a brazed aluminum plate heat exchanger.

The heat exchanger block 2 has a cuboid or block-shaped structure and includes a large number of passages or heating surface elements 3 as well as a large number 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.

The heat exchanger block 2 is assigned a coordinate system with a first spatial direction or width direction x, a second spatial direction or vertical direction y and a third spatial direction or depth direction z. The directions x, y, 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 vertical 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.

The heating surface elements 3 and the separating plates 4 are arranged alternately. This means that a separating plate 4 is positioned between two heating surface elements 3 and a heating surface element 3 is positioned between two separating plates 4. The heating surface elements 3 and the separating plates 4 can be cohesively connected to one another. In cohesive connections, the connection partners are held together by atomic or molecular forces. Cohesive connections are non-detachable connections that can only be separated from one another by destroying the connecting means and/or the connecting partners.

In particular, the heating surface elements 3 and the separating plates 4 can be soldered, in particular hard-soldered, together.

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 have no solder plating. The cover plates 5, 6 are positioned on the outside on an outermost heating surface element 3 and close the heat exchanger block 2 in the orientation of the Fig. 1 forwards and backwards.

Furthermore, the heat exchanger block 2 includes so-called sidebars or edge strips 7, 8, which laterally delimit the heating surface elements 3. The edge strips 7, 8 can be materially connected to the separating plates 4 and/or the heating surface elements 3, for example soldered, in particular hard-soldered. The previously mentioned components of the heat exchanger block 2 are made, for example, from the material 3003 (AlMn1Cu).

With the help of the heating surface elements 3 and the separating plates 4, the plate heat exchanger 1 forms a large number of parallel heat transfer passages in which the process media A to E can flow. Heat can thus be indirectly transferred between process media A to E guided in adjacent heat transfer passages. The individual heat transfer passages can be supplied with a respective process medium A to E with the aid of 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 supplied with the aid of such a connection device 9 to 18 be led away from the plate heat exchanger 1. The connection devices 9 to 18 are so-called headers or can be referred to as such. The connection devices 9 to 18 can also be referred to as distributors or collectors, depending on their function.

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 supplying the process media A, C, D, E from the plate heat exchanger 1 to be discharged.

Each connection device 9 to 18 is assigned a connection piece 19 to 25, with the help 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 led away from the connection device 9 to 18. The connection devices 9 to 18 are materially 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.

The plate heat exchanger 1 can be part of a process engineering system 26. The process engineering 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 engineering system 26 can include a large number of such plate heat exchangers 1.

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

To produce 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 together, in particular hard soldered, using an aluminum solder in a soldering oven. 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.

Leaks in the heat exchanger block 2 usually require the plate heat exchanger 1 or the entire process engineering system 26 to be switched off. Unplanned downtime, repair or replacement leads to higher costs compared to a planned shutdown. Therefore, early leak detection that enables early shutdown planning is desirable. For this purpose, the plate heat exchanger 1 has a leak detection device 27, which will be explained later.

The heat exchanger block 2 has a modular structure and includes 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 on top of one another. The heat exchanger block modules 28, 29 can be firmly connected to one another, for example soldered.

Each heat exchanger block module 28, 29 includes two cover plates 5, 6 as mentioned above. The cover plate 5 of the first heat exchanger block module 28 rests on 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.

Between the cover plates 5, 6 of each heat exchanger block module 28, 29, a large number of heating surface elements 3 and separating plates 4, as mentioned above, are arranged alternately. The heat exchanger block modules 28, 29 are closed off at the edge by edge strips 7, 8.

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 external. In the orientation of the Fig. 3 An empty layer 30 (dummy layer) is provided below the cover plate 6 of the first heat exchanger block module 28. The empty layer 30 comprises a heating surface element 3 as mentioned above, which is arranged between two separating plates 4.

No process medium A to E flows in the empty position 30. The empty position 30 is therefore inactive. In connection with the empty layer 30, “inactive” means that the process media A to E cannot or will not flow through it. The empty layer 30 is open to an atmosphere or environment 31 surrounding the heat exchanger block 2. The empty position 30 is therefore pressureless or there is ambient pressure in the empty position 30.

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. In terms of its structure, the empty layer 32 corresponds to the empty layer 30. The empty layer 32 accordingly comprises a heating surface element 3 which is arranged between two separating plates 4.

Even in the empty position 32, no process medium A to E flows. The empty position 32 is therefore also inactive. The empty layer 32 is also open to the surroundings 31. The empty layer 32 is therefore also unpressurized or there is ambient pressure in the empty layer 32. However, no empty layer 30, 32 as previously mentioned is provided on the cover plates 5, 6 of the heat exchanger block modules 28, 29 that face one another. However, an empty layer 30, 32 as mentioned above can also be provided on the mutually facing cover plates 5, 6 of the heat exchanger block modules 28, 29.

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

In connection with the active areas 33, 34, “active” means that the process media A to E flow through them or can flow through them. In contrast to this, the empty layers 30, 32 are inactive and are not flowed through by the process media A to E. The empty layers 30, 32 are therefore not part of the active areas 33, 34.

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 which is arranged between two separating plates 4. The first leak detection layer 35 is arranged between the empty layer 30 and the active area 33. The first leak detection layer 35 is fluidly separated from the empty layer 30 with the aid 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.

The first leak detection layer 35 is fluidically separated from the active area 33 with a separating plate 4. This aforementioned separation plate 4 can be assigned to the first leak detection layer 35, the active area 33 or both the first leak detection layer 35 and the active area 33.

The first heat exchanger block module 28 further has a second leak detection layer 36. Viewed along the depth direction z, the active area 33 is placed 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 which is 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 area 33.

The second leak detection layer 36 has a separating plate 4, which is firmly connected, in particular soldered, to the cover plate 5. This aforementioned separation 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 area 33. The second leak detection layer 36 is fluidically separated from the active area 33 with a separating plate 4. This aforementioned separation plate 4 can be assigned to the second leak detection layer 36, the active area 33 or both the second leak detection layer 36 and the active area 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”.

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 area 34 is placed between these two leak detection layers 37, 38. The process media A to E also do not flow through the leak detection layers 37, 38. Accordingly, the leak detection layers 37, 38 are also inactive. All leak detection layers 35 to 38 are closed off from the environment 31. However, the leak detection layers 35 to 38 are preferably unpressurized.

Each of the leak detection layers 35 to 38 is assigned a line 39 to 42, which is in fluid connection with the respective leak detection layer 35 to 38. The lines 39 to 42 open into a common collecting line 43. The collecting line 43 branches and leads on the one hand to an analysis unit 44 and on the other hand to 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 Heat exchanger block 2 or plate heat exchanger 1.

The analysis unit 44 is set up to detect and identify chemical substances, such as hydrocarbons, which are contained in the process media A to E. The analysis unit 44 can be a mass spectrometer or have a mass spectrometer. The analysis unit 44 can have a computer, a data memory or the like. The analysis unit 44 can also be suitable for 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 issued.

The overpressure protection unit 45 prevents an undesirable pressure build-up in the leak detection layers 35 to 38. The overpressure protection unit 45 can be or have an overpressure 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.

The leak detection layers 35 to 38 are provided at active areas of the heat exchanger block 2 where leaks are most likely. In the present case, for example, this is an active area where the two heat exchanger block modules 28, 29 are connected to one another and an active area which includes the external cover plates 5, 6. In these aforementioned active areas, high mechanical stresses can occur due to temperature, which can lead to cracks.

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 surroundings 31. In principle, however, the leak detection layers 35 to 38 can be provided anywhere, in particular within the active areas 33, 34. At least exactly one leak detection layer 35 to 38 is provided for leak detection.

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 statements regarding the first leak detection layer 35 can be applied accordingly to the other leak detection layers 36 to 38.

In the event that the separating plate 4 provided between the first detection layer 35 and the active region 33 has a leak, part of the respective process medium A to E flows into the first detection layer 35. It is sufficient here if very small amounts of the respective process medium A to E penetrate from the active area 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.

Chemical analysis looks for chemical substances, such as hydrocarbons, that are contained in the process media A to E. If the analysis is positive, that is, for example, that hydrocarbons are detected, an alarm can be issued, for example. From the analysis unit 44, the leaked process medium A to E is directed or disposed of into a suitable collection area 46, so that the process medium A to E does not escape into the environment 31 reached. The collection area 46 may be a storage container or the like. As a rule, however, the process medium A to E is fed to a flare system.

As a rule, cracks in such a heat exchanger block 2 develop very slowly and become increasingly larger. It is therefore to be 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 previously mentioned collection area 46 over a certain period of time. Meanwhile, a targeted shutdown, replacement and/or repair of the plate heat exchanger 1 or the heat exchanger block 2 can be prepared. It is therefore possible to detect leaks before they become critical for the operation of the plate heat exchanger 1.

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

The method includes a step S1 of flowing through the respective active area 33, 34 with the process media A to E, wherein a heat exchange between the process media A to E is carried out. In a step S2, due to a leak on or in the separating plate 4, process medium A to E penetrating from the active area 33, 34 into the leak detection layer 35 to 38 is chemically analyzed with the aid of the analysis unit 44, whereby the leak is detected. Preferably, the leak detection layer 35 to 38 is kept depressurized during step S2.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

Reference symbols used

1

Plate heat exchanger

2

Heat exchanger block

3

Heating surface element

4

Separation plate

5

Cover plate

6

Cover plate

7

Sidebar

8th

Sidebar

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 engineering plant

27

Leak detection device

28

Heat exchanger block module

29

Heat exchanger block module

30

Empty location

31

Vicinity

32

Empty location

33

active area

34

active area

35

Leak detection location

36

Leak detection location

37

Leak detection location

38

Leak detection location

39

Line

40

Line

41

Line

42

Line

43

manifold

44

Unit of analysis

45

Overpressure protection unit

46

Collection area

A

Process medium

b

Process medium

C

Process medium

D

Process medium

E

Process medium

S1

Step

S2

Step

x

Width direction

y

High direction

e.g

Depth direction

Claims (15)

Plate heat exchanger (1) with an active area (33, 34), through which the process media (A - R) can flow during operation of the plate heat exchanger (1) for heat exchange between different process media (A - E), an inactive empty layer (30, 32 ), which is in fluid communication with an environment (31) of the plate heat exchanger (1), an inactive leak detection layer (35, 37) which is arranged between the active area (33, 34) and the empty layer (30, 32), the Leak detection layer (35, 37) is separated from the active area (33, 34) with the aid of a separating plate (4), and an analysis unit (44) for chemical analysis of the active area due to a leak on or in the separating plate (4). (33, 34) into the leak detection layer (35, 37) penetrating process medium (A - E) in order to detect the leak. Plate heat exchanger according to claim 1, wherein exactly one leak detection layer (35, 37) is arranged between the active area (33, 34) and the empty layer (30, 32). Plate heat exchanger according to claim 1 or 2, wherein the leak detection layer (35, 37) is the separating plate (4), a further separating plate (4) which delimits the leak detection layer (35, 37) from the empty layer (30, 32), and a heating surface element ( 3), which is arranged between the two separating plates (4). Plate heat exchanger according to one of claims 1 - 3, wherein the leak detection layer (35, 37) is depressurized during operation of the plate heat exchanger (1). Plate heat exchanger according to one of claims 1 - 4, further comprising a heat exchanger block (2) which has the active area (33, 34), the empty layer (30, 32) and the leak detection layer (35, 37), wherein the analysis unit (44) is in fluid communication with the leak detection layer (35, 37). Plate heat exchanger according to claim 5, wherein the analysis unit (44) is arranged outside the heat exchanger block (2). Plate heat exchanger according to claim 5 or 6, wherein the analysis unit (44) with the aid of a line (39, 42) leading away from the leak detection layer (35, 37) and a collecting line (43) into which the line (39, 42) opens Fluid connection with the leak detection layer (35, 37). Plate heat exchanger according to one of claims 1 - 7, further comprising an overpressure protection unit (45) which is in fluid communication with the leak detection layer (35, 37). Plate heat exchanger according to claim 8, wherein the analysis unit (44) and the overpressure protection unit (45) are connected in parallel. Plate heat exchanger according to one of claims 1 - 9, further comprising a cover plate (5, 6) which faces the environment (31), the empty layer (30) between the cover plate (5, 6) and the leak detection layer (35, 37) is arranged. Plate heat exchanger according to claim 10, further comprising a first heat exchanger block module (28) with a first cover plate (5) and a second cover plate (6) and a second heat exchanger block module (29) with 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). Plate heat exchanger according to claim 11, further comprising a further inactive leak detection layer (36, 38) between the active area (33) and the first cover plate (5) of the first heat exchanger block module (28) and / or between the active area (34) and the second cover plate (5) of the second heat exchanger block module (29) is arranged. Plate heat exchanger according to one of claims 1 - 12, further comprising a collecting area (46) arranged downstream of the analysis unit (44) for collecting the process medium (A-E) penetrating from the active area (33, 34) into the leak detection layer (35, 37). . Method for operating a plate heat exchanger (1) with an active area (33, 34), an inactive empty layer (30, 32) which is in fluid communication with an environment (31) of the plate heat exchanger (1), an inactive leak detection layer (35, 37 ), which is arranged between the active area (33, 34) and the empty layer (30, 32), the leak detection layer (35, 37) being separated from the active area (33, 34) with the aid of a separating plate (4), and an analysis unit (44), with the following steps: a) Flowing through (S1) the active area (33, 34) with different process media (A - E), whereby a heat exchange between the process media (A - E) is carried out, and b) chemically analyzing (S2) process medium (A-E) penetrating from the active area (33, 34) into the leak detection layer (35, 37) due to a leak on or in the separating plate (4) with the aid of the analysis unit (44) , whereby the leak is detected. Method according to claim 14, wherein the leak detection layer (35, 37) is kept depressurized during step b).

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