Transition piece with thermal insulation

Abstract

The present invention relates to a transition piece (1a, 1b) for joining parts of a chemical or plant engineering device, the transition piece (1a, 1b) comprising a first piece (10) of material made of a first material and a second piece (20) of material made of a second material, the first material and the second material being incompatible with each other by fusion welding, the first piece (10) of material and the second piece (20) of material forming a hollow body, the transition piece (1a, 1b) comprising a radially inner inner surface (2) and a radially outer outer surface (3), the first piece (10) of material being joined to the second piece (20) of material via at least one intermediate material layer (30), and the transition piece (1a, 1b) comprising at least one thermal insulation layer (100, 200), the thermal insulation layer (100, 200) extending over at least a portion of the inner surface (2) and / or the outer surface (3) of the transition piece (1a, 1b). The present invention further relates to a cold box (2000) comprising a core-in-shell heat exchanger (1000) and a transition piece (1a, 1b).

Description

[Technical field]

[0001] The invention relates to a transition piece for joining parts of a chemical or process engineering device, the transition piece comprising a first piece of material made of a first material and a second piece of material made of a second material, the first material and the second material being not joinable to one another by fusion welding, the first piece of material and the second piece of material forming a hollow body, the transition piece comprising an inner surface located radially inward and an outer surface located radially outward, the first piece of material being joined to the second piece of material via at least one intermediate material layer.Furthermore, the invention relates to a core-in-shell heat exchanger comprising the transition piece and a cold box comprising piping comprising the transition piece. [Background technology]

[0002] In particular in cryogenic plants, such as cryogenic heat exchangers for liquefying gases, and in many applications, such as cold boxes for providing liquefied cryogenic gases, or core-in-shell heat exchangers or cryogenic tanks, or cryopumps, it is necessary to join together parts, such as tubes made of different materials, in particular by welding, for example to provide liquid-tightness. The listed plants or equipment are examples or parts of the abovementioned chemical or process engineering equipment.

[0003] For example, to join an aluminum tube to a steel tube, a transition piece (English: transition joint) is used which comprises an aluminum part to which the aluminum tube is fixed, in particular can be welded, and a steel part to which the steel tube is fixed, in particular can be welded. To join the aluminum part of the transition piece and the steel part of the transition piece liquid-tight, various intermediate material layers, for example made of metals such as titanium or titanium alloys, copper, nickel or copper-nickel alloys, are arranged in several layers by means of an explosive welding process between the aluminum part and the steel part of the transition piece. On the one hand, this manufacturing method is very costly. On the other hand, the intermediate material layers made of metals are subjected to high physical stresses by the explosive welding process, so that they may become brittle or prone to breakage.

[0004] Other types of joint pieces or structures are also known from the prior art.

[0005] US 3,899,007 (A) and US 3,747,961 (A) each describe a tube arrangement with a high-temperature resistant central tube held in a coaxial housing tube by anchors or anchor plates to protect it from axial or longitudinal movements. The anchors are projected from this housing and are located on the outer surface of an insulating layer, for example made of concrete. The central tube is in turn surrounded by an insulating annular layer. FR 2,947,032 (A1) proposes joining two tubes via a flange or a joint structure. Each of the two tubes has an inner wall and an outer surrounding wall, the inner wall being guided towards the outside at the tube end. The joint structure also has an outer surface and an inner surface, so that when the two tubes are joined, the inner wall is located on the inner surface of the joint structure at the tube end.

[0006] It is an object of the present invention to provide a transition piece which is easier to manufacture and has advantageous properties compared to known transition pieces.

[0007] Disclosure of the Invention According to the invention, a transition piece, a core-in-shell heat exchanger and a cold box are proposed having the technical features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0008] A transition piece according to the invention for joining parts of chemical or process engineering equipment, in particular in cryogenic plants, comprises a first piece of material made of a first material and a second piece of material made of a second material, the first material and the second material being unable to be joined to one another by fusion welding.

[0009] The transition piece or the first and second pieces of material have the shape of a hollow body, in particular a torus, ring or cylinder shape, with an inner surface located radially inward and an outer surface located radially outward. The transition piece is suitable for being joined to a pipe of a chemical or process engineering device, the shape of the transition piece preferably being adapted to the shape of the pipe.

[0010] The first piece of material is joined to the second piece of material via at least one intermediate layer of material, in particular made of metal, which is arranged between the first and second pieces of material or attached to the first and / or second pieces of material, in particular by means of explosive bonding.

[0011] Prior art transition pieces are subject to high thermal loads. For example, when a cryogenic fluid flows through the transition piece, the inner surface of the transition piece cools quickly and significantly, causing the temperature of the inner surface of the transition piece to change compared to the temperature of the outer surface. Due to temperature differences and different thermal expansion coefficients of the individual materials, strains can occur between the inner and outer surfaces and / or between the individual materials within the transition piece, which can lead to cracks, breakage, and the like.

[0012] This temperature difference between the inner and outer surfaces affects the at least one intermediate material layer such that the inner surface of the at least one intermediate material layer tends to contract more than the outer surface thereof, thus causing distortion in the at least one intermediate material layer as well.

[0013] For example, these distortions may result in additional loads on at least one intermediate material layer that has been loaded by the explosive welding process, which may lead to the formation of cracks or breaks in the intermediate material layer, which may then result in leaks in the transition piece, for example, leading to the leakage of the cryogenic fluid. This drawback does not occur with the transition piece proposed according to the invention.

[0014] The transition piece of the present invention includes at least one insulating layer that extends over at least a portion of the inner and / or outer surface of the transition piece.

[0015] "Partly" here means, for example, that the thermal insulation layer is arranged only on at least one intermediate material layer, and may also be arranged on at least one intermediate material layer and on at least a portion of the first piece of material and / or on at least a portion of the second piece of material.

[0016] When at least one insulating layer is disposed on an inner surface of the transition piece, the layer insulates at least a portion of the transition piece from the cryogenic fluid, thereby reducing the temperature difference between the inner and outer surfaces of the transition piece. This further reduces distortion of the transition piece. When at least one insulating layer is disposed on an outer surface of the transition piece, the layer insulates at least a portion of the transition piece from the ambient temperature, e.g., the outside air temperature, thereby reducing the temperature difference between the inner and outer surfaces of the transition piece.

[0017] Therefore, at least one thermal barrier generally improves the life of the transition piece.

[0018] For example, if one insulation layer is placed on the inside and one on the outside of the transition piece, the temperature differential can be further reduced, thereby extending the life of the transition piece.

[0019] Preferably, the at least one thermal insulation layer is arranged such that it covers the first piece of material, the at least one intermediate material layer and the second piece of material, such that the first piece of material, the at least one intermediate material layer and the second piece of material have substantially the same temperature, in such a way that distortions between the two parts, e.g. due to a clear temperature difference between the first piece of material and the at least one intermediate material layer, can be prevented, e.g. so that the first piece of material and / or the at least one intermediate material layer are not damaged or destroyed.

[0020] The thermal insulation layer, preferably disposed on the outer surface of the transition piece, is a cladding. The cladding is formed as a hollow body and may be toroidal, annular or cylindrical in shape. The thermal insulation layer in the form of a cladding is mounted on the transition piece, enveloping or containing it. The cladding may be adapted and selected accordingly depending on the location and respective use of the transition piece.

[0021] When the first piece of material is joined to a first pipe of a first material and the second piece of material is joined to a second pipe of a second material, the cladding preferably covers a portion of the first pipe and / or a portion of the second pipe, where "pipe" may particularly refer to a portion of the pipe to or from the heat exchanger.

[0022] For example, the first piece of material is joined, in particular welded, to the first pipe. If the cladding only covered the transition piece, as is the case for example with prior art transition pieces, this would result in, for example, temperature differences between the first piece of material and the first pipe causing distortions between the first piece of material and the first pipe. This could result in damage to the weld seam and lead to the escape of the cryogenic fluid.

[0023] For example, if the cladding extends over the entire bond area between the first piece of material and the first piping, strain between the first piece of material and the first piping is reduced and the bond is protected compared to the prior art.

[0024] Preferably, the cladding comprises metal and / or plastic and / or ceramic and / or concrete. The cladding may be implemented in various embodiments. In one embodiment, the cladding may be provided in the form of a tube, in particular a thermal protection tube. This tube surrounds the transition piece and / or the piping connected thereto and may be fixed to the transition piece and / or the piping connected thereto by a material connection (e.g. by means of welding) or a form connection (e.g. by means of threads).

[0025] In an alternative embodiment, the cladding may be in the form of a plastic mat, which is placed around the transition piece and / or the pipe connected thereto. As a fastening material, for example, a sleeve is used here.

[0026] In another embodiment, the cladding may be formed into a structure with a cavity made of plastic, the structure having a cavity that is, for example, hexagonal, rectangular or circular, and the cavity is filled with a gas or the cavity is evacuated.

[0027] Additionally, foam insulation and / or polystyrene foam may also be used as the cladding.

[0028] Preferably, the heat insulating layer arranged on the inner surface of the transition piece is a heat resistant wall. The heat resistant wall is formed as a hollow body and has a torus, ring or cylinder shape. Furthermore, the heat resistant wall is connected to the transition piece by a form connection, such as by screws, and / or a material connection, such as by gluing, so that the cryogenic fluid flowing through the transition piece cannot move or remove the heat resistant wall. Furthermore, the heat resistant wall is connected to the transition piece in such a way that the cryogenic fluid does not reach between the heat resistant wall and the transition piece. This would allow, for example, the connection between the heat resistant wall and the transition piece to be loosened or removed. Furthermore, if the cryogenic fluid is between the transition piece and the heat resistant wall, it may disrupt the insulation of the transition piece.

[0029] Preferably, the heat-resistant wall comprises aluminum oxide ceramic, concrete, a plastic structure with a cavity, foam insulation and / or polystyrene foam, or a mixture thereof. The concrete or foam insulation can be shaped or poured into the heat-resistant wall, for example. The aluminum oxide ceramic can be manufactured to have the shape of the heat-resistant wall, for example. It is self-evident that depending on the application, the material of the heat-resistant wall can be preferred by a person skilled in the art.

[0030] Furthermore, in the transition piece of the present invention, the first material is steel or stainless steel, and the second material is aluminum or an aluminum alloy. In cryogenic plants, especially for liquefying gases, such as cryogenic heat exchangers, or cryogenic tanks and cryogenic pumps, steel and aluminum tubes are often used. Aluminum and steel (or their alloys) cannot be welded. Therefore, the transition piece is suitable for creating a transition between a steel tube and an aluminum tube, and the joint is formed liquid-tight.

[0031] Preferably, at least one intermediate material layer is a silver layer, a nickel layer or a nickel titanium layer. These materials can be joined to the first and / or second material pieces using explosive bonding, thus making it possible to join the first and second material pieces. The bond created in this way is liquid-tight, so that for example cryogenic fluids cannot escape. Furthermore, the bond between the first and second material pieces cannot be released. It is self-evident that the number and the materials used can be selected and changed depending on the application of the transition piece. When choosing multiple intermediate material layers, it is possible to use, for example, one or more silver, nickel and / or nickel titanium layers as intermediate material layers.

[0032] The core-in-shell heat exchanger according to the invention comprises a plate heat exchanger arranged in an external tank of the core-in-shell heat exchanger, the plate heat exchanger comprising a supply pipe through which a fluid can be fed to the plate heat exchanger and a discharge pipe through which a fluid can be removed from the plate heat exchanger, and at least one transition piece according to the invention is arranged in the supply pipe and / or the discharge pipe.

[0033] In a core-in-shell heat exchanger (also called a block-in-shell, block-in-kettle or plate-and-shell heat exchanger, the terms are synonymous), at least one plate heat exchanger, the so-called "core", is placed inside an external tank, also called the "shell".

[0034] Core-in-shell heat exchangers are used to realize indirect heat transfer, for example from a gaseous fluid to a liquid fluid. The gaseous fluid is fed into the plate heat exchanger, for example from the outside, via a first feed pipe, and the liquid fluid is prepared in an external tank so that the liquid fluid surrounds the plate heat exchanger. In the plates of the plate heat exchanger, indirect thermal contact occurs, the gaseous fluid is cooled and liquefied, and the liquid fluid is at least partially transferred to a gaseous condensed state. However, core-in-shell heat exchangers are also suitable for other types of heat transfer.

[0035] The use of core-in-shell heat exchangers has the advantages of closer QT curves, smaller size and lighter weight, lower manufacturing and operating costs, etc. Core-in-shell heat exchangers are described, for example, in K. Thulukkanam, Heat Exchanger Design Handbook, 2nd Edition, CRC Press 2013, page 127 and illustrated in Figure 4.25, as compared to tube bundle heat exchangers. Core-in-shell heat exchangers are disclosed, for example, in EP 3237825 A1, WO 2016 / 102046 A1, WO 2016 / 102045 A1, WO 2016 / 000812 A1, EP 3143352 A1, EP 3077750 A1, DE 102012011328 A1 and DE 102011013340 A1.

[0036] The plate heat exchanger is at least partially made of the above-mentioned second material, which cannot be welded to the first material, which is normally used for the majority of the piping, and thus the supply and / or discharge pipes preferably comprise a first pipe made of the first material and a second pipe made of the second material, which first and second materials cannot be joined to each other by fusion welding, the second pipe being joined on the one hand to the plate heat exchanger and on the other hand to a transition piece according to the invention, which transition piece is used to join the first and second pipes.

[0037] Since the second pipe and the plate heat exchanger are made of the same material, they can be joined to each other, for example by welding. This joint is liquid-tight, so that the fluid fed to the plate heat exchanger reaches the plate heat exchanger and does not flow beforehand into the external tank of the core-in-shell heat exchanger. The transition piece also ensures that the joint between the first pipe and the second pipe is liquid-tight.

[0038] Here again, the first material is steel or stainless steel and the second material is aluminum or an aluminum alloy. The plate heat exchanger is therefore in particular made of aluminum. This is advantageous since the high thermal conductivity of aluminum allows good heat transfer between the two fluids. Furthermore, the plate heat exchanger can be easily manufactured, for example by brazing.

[0039] A cold box according to the present invention comprises piping that includes at least one transition piece according to the present invention.

[0040] A cold box is a thermally insulated enclosure in which process engineering equipment operating at low, in particular cryogenic, temperatures is installed. A process engineering plant comprises one or more corresponding cold boxes, in particular it can be made modular from corresponding cold boxes. Process engineering plants equipped with cold boxes are, for example, plants for air cracking or plants for decomposing synthesis gas into its components hydrogen, nitrogen and carbon dioxide. In such processes temperatures are below -180 ° C. The invention is suitable for all fields of use of cold boxes, without being limited to these examples. In the cold box, several plant components, such as separation devices such as columns and associated heat exchangers, can also be fixed together with piping to a supporting steel frame that is sheathed from the outside with metal sheets. The interior of the enclosure thus formed is filled with an insulating material, for example perlite, to prevent heat input from the surroundings. It is also possible to partially or completely prefabricate the cold box with the corresponding equipment in the factory, so that they only have to be finally assembled or joined together at the construction site as required. For the joining, piping modules can be used that are thermally insulated and, if necessary, stored in the cold box. In a typical cold box, the plant components are often mounted with minimal spacing between the walls to ensure adequate insulation.

[0041] The piping in the cold box according to the invention is preferably implemented without flange connections, i.e. either entirely welded or via at least one transition piece according to the invention, to avoid the occurrence of leaks. Due to the temperature differences that arise, expansion bending of the piping can occur. The interior of the cold box is advantageously maintenance-free, since no parts requiring maintenance are usually arranged in the cold box. The valves can be implemented, for example, as so-called angle valves, allowing repairs from the outside. In this case, the valves are in the wall of the cold box, and the lines run to the valves and back again. The lines and the devices are usually implemented in aluminum, and also noble metals are used in the case of very high operating pressures. The transition piece according to the invention allows the joining of these materials. The painting of the cold box is mostly white, but also implemented in other light colors. The ingress of moisture from the outside air that has frozen in contact with the cold plant components can be prevented, for example, by continuously purging the cold box with nitrogen.

[0042] Other advantages and embodiments of the present invention will become apparent from the description and accompanying drawings.

[0043] It is obvious that the technical features described above and below can be used in other combinations or alone, without departing from the framework of the present invention, in addition to the combinations described above.

[0044] The invention is illustrated diagrammatically by means of an embodiment shown in the drawing and is explained below with reference to the drawing. [Brief description of the drawings]

[0045] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of a preferred embodiment of a transition piece according to the present invention with cladding. [Diagram 2] FIG. 2 is a longitudinal cross-sectional view of a preferred embodiment of a transition piece according to the present invention with a heat resistant wall. [Diagram 3] FIG. 1 is a diagram of a preferred embodiment of a core-in-shell heat exchanger. [Figure 4] FIG. 2 is a diagram of a preferred embodiment of a cold box.

[0046] In the drawings, the same reference numerals represent the same or structurally identical elements and are not described separately each time.

[0047] In FIG. 1 a preferred embodiment of a transition piece according to the invention with cladding is shown in longitudinal section and designated by the reference number 1a.

[0048] The transition piece 1a comprises a first piece of material 10, a second piece of material 20 and an intermediate material layer 30. The transition piece 1a or the first piece of material 10, the intermediate material layer 30 and the second piece of material 20 have a hollow cylindrical shape with an inner surface 2 located radially inwards and an outer surface 3 located radially outwards. The first piece of material 10 consists of steel, the intermediate material layer 30 consists of nickel and the second piece of material 20 consists of aluminum, such that it is not possible to join the first piece of material 10 to the second piece of material 20 by fusion welding. The first piece of material 10 is joined to the steel tube 4 and the second piece of material 20 to the aluminum tube 5, in particular by welding.

[0049] The first material piece 10 and the second material piece 20 each have thin portions 41, 42 and thick portions 51, 52, and the thick portions 51, 52 have a thickness that is about 2 to 5 times that of the thin portions 41, 42.

[0050] Between the thickened portion 51 of the first piece of material 10 and the thickened portion 52 of the second piece of material 20, an intermediate material layer 30 is arranged. The intermediate material layer 30 is then joined to the first piece of material 20 by means of an explosive welding method. The intermediate material layer 30 is then joined to the first piece of material 10, where this joining is made by means of an explosive welding method. In this case, the thickened portions 51, 52 serve in particular to provide a sufficient surface on which the intermediate material layer 30 can be attached. The role of the intermediate material layer 30 here is therefore to join the first piece of material 10 and the second piece of material 20. The joining created in this way is liquid-tight, so that for example cryogenic fluids cannot escape. Furthermore, the joining of the first piece of material 10 and the second piece of material 20 is irremovable.

[0051] However, because the intermediate layer 30 is subjected to high physical stresses by the explosive bonding process, the intermediate layer 30 may become brittle and susceptible to breakage.

[0052] In particular, in a cryogenic plant where a cryogenic fluid flows through the transition piece 1a, the cryogenic fluid cools the loaded transition piece 1a from the inner surface 2 to the outer surface 3. Thus, the intermediate material layer 30 also cools and contracts due to the cooling. These additional forces can damage or break the embrittled intermediate material layer 30, causing the transition piece 1a to leak. The greater the temperature difference between the inner surface 2 and the outer surface 3 of the transition piece 1a, the greater the forces acting on the intermediate material layer.

[0053] In order to reduce the temperature difference between the inner surface 2 and the outer surface 3 of the transition piece 1a, the transition piece 1a further comprises a cladding 100, in particular a thermal insulation in the form of a thermal protection tube. The cladding 100 is formed as a hollow body and has a torus, ring or cylindrical shape. The cladding 100 is arranged on the outer surface 3 located radially outwardly of the transition piece 1a so as to enclose it. With such an arrangement, the first piece of material 10, the intermediate material layer 30 and the second piece of material 20 have approximately the same temperature. The reduced temperature difference between the inner surface 2 and the outer surface 3 of the intermediate material layer 30 reduces distortions occurring in the intermediate material layer 30.

[0054] Additionally, less strain is generated, for example between the first piece of material 10 and the intermediate layer of material 30, which may cause damage or destruction to the first piece of material 10 and / or the intermediate layer of material 30. Thus, the cladding 100 improves the life of the transition piece 1a.

[0055] Furthermore, the cladding 100 is at least partially suspended on the steel tube 4 and the aluminum tube 5. This is advantageous because a temperature difference between the first piece of material 10 and the steel tube 4 can lead to distortions between the first piece of material 10 and the steel tube 4. These distortions can, for example, damage the weld seam between the first piece of material 10 and the steel tube 4.

[0056] FIG. 2 is a longitudinal cross-sectional view of another preferred embodiment of a transition piece 1b according to the present invention with a heat resistant wall.

[0057] 1 in that transition piece 1b includes thermal insulation in the form of a thermal barrier 200. Thermal barrier 200 is formed as a hollow body and may be toroidal, annular or cylindrical in shape, for example an aluminum oxide ceramic.

[0058] The heat-resistant wall 200 is disposed on the inner surface 3 located radially outwardly so as to enclose the transition piece 1b. With this arrangement, the first material piece 10, the intermediate material layer 30, and the second material piece 20 have substantially the same temperature. The smaller temperature difference between the inner surface 2 and the outer surface 3 of the intermediate material layer 30 reduces distortion occurring in the intermediate material layer 30.

[0059] Furthermore, less strain is generated, for example between the first piece of material 10 and the intermediate layer of material 30, which may cause damage or destruction to the first piece of material 10 and / or the intermediate layer of material 30. Thus, the thermal barrier 200 improves the life of the transition piece 1b.

[0060] Furthermore, the heat-resistant wall 200 at least partially rests on the steel tube 4 and the aluminum tube 5. This is advantageous because a temperature difference between the first piece of material 10 and the steel tube 4 can lead to distortions between the first piece of material 10 and the steel tube 4. These distortions can, for example, damage the weld seam between the first piece of material 10 and the steel tube 4.

[0061] The heat resistant wall 200 has a trapezoidal cross section and has a sloped or flattened edge 210 extending from the inside to the outside of the heat resistant wall 200, which allows the cryogenic fluid to flow through the transition piece 1b without the heat resistant wall 200 significantly increasing the through-flow resistance, as would occur if the edge were vertical.

[0062] Here, the thermal barrier 200 is connected to the transition piece, particularly by screws, so that the cryogenic fluid flowing in the transition piece 1b cannot move or remove the thermal barrier 200. Furthermore, the thermal barrier 200 is connected to the transition piece 1b in such a way that the cryogenic fluid cannot reach between the thermal barrier 200 and the transition piece 1b. This would allow, for example, the connection between the thermal barrier 200 and the transition piece 1b to be loosened or removed. Furthermore, if the cryogenic fluid is between the transition piece 1b and the thermal barrier 200, it may disrupt the insulation of the transition piece 1b.

[0063] A preferred embodiment of the core-in-shell heat exchanger 1000 of the present invention is shown diagrammatically in Figure 3. The core-in-shell heat exchanger 1000 comprises an external tank 1100 (shell) and a plate heat exchanger 1200 disposed in the external tank 1100.

[0064] The plate heat exchanger 1200 includes a plurality of plates 1300. The plate heat exchanger 1200 and the plates 1300 are brazed together, for example, from aluminum.

[0065] The plates 1300 are arranged to transfer the heat of a fluid A, for example natural gas, to a fluid B, for example a refrigerant (for example a mixture of ethylene and propylene). For this purpose, the fluid A present in gaseous phase can be fed from the outside into the core-in-shell heat exchanger 1000 or into the plate heat exchanger 1200 through a first feed pipe 1400, i.e. the fluid A flows through the plates 1300 of the plate heat exchanger. The fluid A is then cooled and can be discharged or removed from the plate heat exchanger 1200 and the core-in-shell heat exchanger 1000 through a first discharge pipe 1500, which contains aluminium as liquid.

[0066] At this time, the heat of fluid A is transferred to fluid B in the plates 1300 and is sent as liquid and / or gas (here a two-phase mixture) to the external tank 1100 of the core-in-shell heat exchanger 1000 via the second supply pipe 1600. Fluid B flows between the plates 1300 of the plate heat exchanger 1200, and the liquid components of fluid B transition to a gaseous state. The gaseous components of fluid B are heated to a high temperature. Fluid B in the gaseous phase can then be removed from the core-in-shell heat exchanger 1000 via the second outlet pipe 1700. The second supply pipe 1600 and the second outlet pipe 1700 comprise, for example, steel.

[0067] Here, the first supply pipe 1400 comprises a steel pipe 4 and an aluminum pipe 5, the entire aluminum pipe 5 and part of the steel pipe 4 being arranged inside the external tank 1100. The aluminum pipe 5 is welded to the plate heat exchanger 1200. The steel pipe 4 is used for joining, in particular by welding, for example to a steel pipe of a tank in which the fluid A is present.

[0068] Furthermore, a transition piece 1a (in FIG. 1 ) is arranged between the steel tube 4 and the aluminum tube 5. The transition piece 1a is used to join the steel tube 4 and the aluminum tube 5 in a liquid-tight manner. To this end, the transition piece 1a comprises a first piece of material 10 comprising steel, a second piece of material 20 comprising aluminum, and an intermediate material layer 30 comprising nickel, which is arranged between the first piece of material 10 and the second piece of material 20 by means of an explosive welding method. The first piece of material 10 is welded to the steel tube 4 and the second piece of material 20 is welded to the aluminum tube 5.

[0069] Inside the first supply pipe 1400, where the gas phase fluid A is delivered to the plate heat exchanger 1200, the temperature is higher than outside the first supply pipe 1400. This temperature difference and the different thermal expansion coefficients of the individual materials can cause distortions between the outer and inner surfaces and / or between the individual materials, e.g., at welded seams, in the transition piece 1a and / or the first supply pipe 1400. This can cause, for example, cracks or breaks in the first supply pipe 1400 or the individual materials.

[0070] The cladding 100 of the transition piece 1a in this embodiment extends over the portion of the first supply pipe 1400 located inside the external tank 1100, which reduces distortion and also prevents possible leakage of the gas phase fluid A due to, for example, cracks or breaks in the weld seam.

[0071] It is self-evident that the use of the transition piece 1a in the first supply pipe 1400 here is only one example. Furthermore, additional transition pieces can be laid in or on the core-in-shell heat exchanger 1000. For example, if the second supply pipe 1700 containing steel needs to be joined to a pipe not containing steel outside the core-in-shell heat exchanger 1000 and therefore direct welding to the second supply pipe 1700 is not possible, a corresponding transition piece could be used.

[0072] Furthermore, in cases where the first exhaust pipe 1500 needs to comprise steel, a direct connection between the first exhaust pipe 1500 and the plate heat exchanger 1200 may not be feasible. Here, the use of an additional transition piece is envisaged.

[0073] The core-in-shell heat exchanger 1000 is just one example of the application of the transition piece. Furthermore, it is also useful to use the transition piece in a cold box installation or cold box for short. The cold box installation is used for air cracking or for cracking synthesis gas and for this purpose comprises a number of heat exchangers and / or cold chambers as process engineering devices through which the air or synthesis gas flows. The transition piece can be attached, for example, to the piping used to remove certain components of the air or synthesis gas from the cold box installation after separation. The individual components are filled and stored, for example, in steel or stainless steel tanks, whereas the heat exchanger comprises, for example, aluminum, so that the use of the transition piece here is preferred, since the use of the transition piece makes it easier to join the aluminum piping of the heat exchanger with the piping of the stainless steel tank.

[0074] FIG. 4 shows, by way of example, an air cracking installation 2100 of a type known in the art, the components of which are at least partially disposed within a cold box 2000.

[0075] Air cracking installations of the illustrated type have been described many times in other publications, for example in H.-W. Haering (Ed.), Industrial Gases Processing, Wiley-VCH, 2006, in particular in section 2.2.5 "Cryogenic Rectification". For a detailed description of their construction and function, reference should therefore be made to the corresponding specialist publications. The air cracking installations used in the present invention may be designed in various ways.

[0076] 4 may include a main air compressor, precooling system, scrubbing system, and booster compressor assembly in what is referred to as the high temperature section 2200, which is only shown diagrammatically to the left of the cold box 2000 and not shown in detail. Inside the cold box 2000, the plant engineering equipment includes a main heat exchanger 2110 and a distillation column system 2120. The distillation column system 2120 is, in the illustrated example, a conventional double column arrangement of a high pressure column 2122 and a low pressure column 2124 heat exchangeably joined to each other via a main condenser 2126.

[0077] Pressurized working air flows are fed to the cold box 2000 in the direction of the arrows and via pipes 2002, 2004 which are coupled to the cold box 2000 by means of transition piece 1a. One of the working air flows, after partial cooling in the main heat exchanger 2110, can be removed via pipe 2006 which is coupled to the cold box 2000 by means of transition piece 1a, for example depressurized outside the cold box 2000 and fed back into the cold box 2000 via pipe 2008 which is coupled to the cold box 2000 by means of transition piece 1a.

[0078] The transition piece 1 a joins the exterior piping of the cold box 2000 to the aluminum piping inside the cold box 2000 .

[0079] An oxygen-enriched liquid bottoms fraction and a nitrogen-enriched vapor phase overhead fraction are formed in high pressure column 2122. The oxygen-enriched liquid bottoms fraction is withdrawn from high pressure column 2122 and transferred to low pressure column 2124. A vapor phase nitrogen-enriched overhead product is withdrawn from the top of high pressure column 2122, liquefied in main condenser 2126, fed fractionally to high pressure column 2122 as reflux, and sent to low pressure column 2124 to be reduced in pressure and exit air cracking system 2100 as liquid product LIN.

[0080] The low pressure column 2124 produces an oxygen-enriched liquid bottom fraction and a nitrogen-enriched vapor top fraction. The former is partially compressed in liquid form in a pump connected to a motor M, heated in a main heat exchanger 2110, and provided as a vapor-phase compressed product GOX. The fraction not compressed in liquid form in the pump can be exported from the air cracking system 2100 as a liquid oxygen product LOX. A vapor-phase oxygen-enriched stream withdrawn from the top of the low pressure column 2124 is passed through the main heat exchanger 2110 and provided as a nitrogen product GAN.

[0081] It is self-evident that the preferred embodiments according to figures 1 and 2 can be combined. For example, the transition piece can be provided with a cladding 100 and a heat-resistant wall 200. This further reduces the temperature difference between the inner surface 2 and the outer surface 3 of the transition piece, which allows to extend the life of the transition piece. In the plant of figures 3 or 4, it would also be possible to use transition piece 1b or two transition pieces or transition pieces different from those previously shown.

Claims

1. A core-in-shell heat exchanger (1000) comprising a plate heat exchanger (1200) arranged in an external tank (1100), a supply pipe (1400) through which a fluid can be fed into the plate heat exchanger (1200), and a discharge pipe (1500) through which the fluid can be removed from the plate heat exchanger (1200), the core-in-shell heat exchanger having at least one transition piece (1a, 1b) for joining parts of a chemical or process engineering apparatus, the transition piece (1a, 1b) is arranged in the supply pipe (1400) and / or the discharge pipe (1500), The transition piece (1a, 1b) comprises a first piece (10) made of a first material and a second piece (20) made of a second material, the first material and the second material being incompatible with each other by fusion welding, the first piece (10) and the second piece (20) forming a hollow body, the transition piece (1a, 1b) having an inner surface (2) located radially inward and an outer surface (3) located radially outward, the first piece (10) having at least one intermediate material layer ( a first material being joined to the second piece of material (20) via a first insulating layer (30) and the transition piece (1a, 1b) comprises at least one insulating layer (100, 200) extending over at least a portion of the inner surface (2) and / or the outer surface (3) of the transition piece (1a, 1b), the first material being steel or stainless steel and the second material being aluminum or an aluminum alloy.

2. 2. The core-in-shell heat exchanger (1000) of claim 1, wherein the at least one insulating layer (100, 200) is arranged such that the insulating layer covers the first piece of material (10), the at least one intermediate layer of material (30) and the second piece of material (20).

3. 3. The core-in-shell heat exchanger (1000) according to claim 1 or 2, characterized in that the insulating layer (100, 200) arranged on the outer surface (3) of the transition piece (1a, 1b) is a cladding (100).

4. 4. The core-in-shell heat exchanger (1000) of claim 3, characterized in that in a transition piece in which the first material piece (10) is joined to a first pipe (4) made of the first material and the second material piece (20) is joined to a second pipe (5) made of the second material, the cladding (100) further covers a portion of the first pipe (4) and / or a portion of the second pipe (5).

5. Core-in-shell heat exchanger (1000) according to claim 3 or 4, characterized in that the cladding (100) comprises metal and / or plastic and / or ceramic and / or concrete.

6. 3. The core-in-shell heat exchanger (1000) according to claim 1 or 2, characterized in that the insulating layer (100, 200) arranged on the inner surface (2) of the transition piece (1a, 1b) is a heat-resistant wall (200).

7. 7. The core-in-shell heat exchanger (1000) of claim 6, wherein the heat-resistant wall (200) comprises aluminum oxide ceramic, concrete, plastic honeycomb structure, foam insulation and / or polystyrene foam, or a mixture thereof.

8. The core-in-shell heat exchanger (1000) according to any one of claims 1 to 7, characterized in that said at least one intermediate material layer (30) is a metallic layer.

9. The core-in-shell heat exchanger (1000) of claim 8, characterized in that the metal layer is selected from a silver layer, a nickel layer or a nickel titanium layer.

10. 10. The core-in-shell heat exchanger (1000) according to claim 9, characterized in that the plate heat exchanger (1200) is made of the second material, the supply pipe (1400) and / or the discharge pipe (1500) comprises a first pipe (4) made of the first material and a second pipe (5) made of the second material, the second pipe (5) being joined to the plate heat exchanger (1200), the first pipe (4) being joined to the second pipe (5) via the at least one transition piece (1a, 1b).

11. A cold box (2000) comprising at least one process engineering apparatus (2110, 2120), in which the piping inside said at least one process engineering apparatus (2110, 2120) and / or in case of a plurality of process engineering apparatuses, the piping between at least two process engineering apparatuses (2110, 2120) and / or the supply pipes (2002, 2004) to said cold box (2000) and / or the discharge pipes (2006, 2008) from said cold box (2000) have at least one transition piece (1a, 1b) for joining parts of a chemical or process engineering apparatus, The transition piece (1a, 1b) comprises a first piece (10) made of a first material and a second piece (20) made of a second material, the first material and the second material being incompatible with each other by fusion welding, the first piece (10) and the second piece (20) forming a hollow body, the transition piece (1a, 1b) having an inner surface (2) located radially inward and an outer surface (3) located radially outward, the first piece (10) being formed of at least one intermediate material. a first material being joined to the second piece of material (20) via a material layer (30), the transition piece (1a, 1b) comprising at least one insulating layer (100, 200) extending over at least a portion of the inner surface (2) and / or the outer surface (3) of the transition piece (1a, 1b), the first material being steel or stainless steel and the second material being aluminum or an aluminum alloy.

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