Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/10—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically
  • F28D7/103—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically consisting of more than two coaxial conduits or modules of more than two coaxial conduits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B39/00—Evaporators; Condensers
  • F25B39/02—Evaporators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/02—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being helically coiled
  • F28D7/026—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being helically coiled the conduits of only one medium being helically coiled and formed by bent members, e.g. plates, the coils having a cylindrical configuration
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit

Definitions

• the invention relates to an assembly for cooling a gas using an evaporating first refrigerant, which is preferably to be brought into contact with the gas to be cooled and is preferably a film-evaporating first refrigerant, comprising: a gas cooler of the gap type, having a multiplicity of plate-like wall elements which are arranged parallel to one another, leaving open gaps which are delimited between them and, at opposite ends, are connected to in each case a different adjoining gap to form a series of gaps; and a refrigerant cooler for cooling, in particular supercooling, a second refrigerant.
• An assembly of this type is known. Referring to Claims 1 to 3, the applicant, Grasso Products B.
• Interstage Cooling System B has already been supplying assemblies of this nature for many years under the name "Interstage Cooling System B", cf. Fig. 2.
• This known interstage cooling system B is in fact a combination of a compressed-gas cooler (19), as has already been marketed by the applicant for a number of years under the name "Interstage Cooling System A”, and a separate refrigerant cooler (18), in particular a liquid supercooler.
• the interstage cooling system A which has already been marketed for a number of years by the applicant is a gas cooler (19) of the gap type and essentially comprises a multiplicity of pipes which are fitted into one another with spaces between them and are arranged vertically.
• the hot compressed gas and injected, evaporating refrigerant is passed through the series of gaps while the refrigerant evaporates, cooling the hot gas in the process, in order subsequently, at the end of the series, to be passed through to the HP side (2) via the outlet of the gas cooler (19).
• the injection of the refrigerant, which has been branched off from the HP side (2), into the hot gas originating from LP side (1) is controlled by a thermostatic expansion valve (11) which is actuated (13) by a temperature and/or pressure sensor (12) positioned on/in/at the outlet of the gas cooler (19).
• the separately arranged supercooler (18) is in fact nothing other than a conventional heat exchanger in which two separate channel systems, which are arranged so as to exchange heat, are accommodated.
• Expanded refrigerant which originates from the HP side (2) and has been branched off is passed through the first channel system, and the main stream of refrigerant, which remains after refrigerant has been branched off, is passed through the second channel system, the main stream of refrigerant then being supercooled further by further expansion of the stream of refrigerant which has been branched off. Then, after it has left the heat exchanger (18), the stream of refrigerant which has been branched off from the HP side (2) is used for injection into the stream (9) of hot gas originating from the LP side (1), in order then to be guided, together with the hot gas, through the above-described gas cooler (19) of the gap type with pipes which have been fitted into one another.
• Interstage cooling assemblies of this type having a gas cooler of the gap type and a separate liquid supercooler are known on a more general basis than simply those originating from the applicant, and are also supplied by other suppliers.
• a separate refrigerant cooler or liquid supercooler has the drawback that this cooler has to be fitted separately and/or supplied as a separate part, that it takes up relatively large amounts of space, that the joints and connections of such plate heat exchangers, which are often soldered, are relatively weak and are not able to successfully withstand vibrations.
• a separate refrigerant cooler occurs specifically in the case of refrigerants which have a high heat of evaporation in combination with a low specific gravity/low relative density, in which case, after expansion, a high volumetric proportion of gas is formed, and therefore a very low volumetric proportion of liquid.
• a refrigerant of this type is ammonia. With a refiigerant of this type, it is not possible at a technical level to distribute the remaining liquid refrigerant/liquid which is still to be evaporated over a heat exchanger with a plurality of parallel channels/pipes.
• the object of the present invention is to provide an improved assembly of the type described in the introduction, which improved assembly overcomes the above problems, at least some of these problems.
• refrigerant cooler comprises a channel or system of channels which is formed in at least one of the multiplicity of wall elements and is separated from the series of gaps.
• refrigerant cooler or refrigerant supercooler in the gas cooler by forming a channel or channel system in at least one of the walls delimiting the gaps, through which channel or channel system the refrigerant which is to be (super)cooled is passed in order for heat to be extracted from it.
• the assembly comprises isolating means which, at least during operation, completely or partially isolate the at least one wall element provided with the channel or channel system from the gas stream which is to be cooled.
• isolating means of this nature can be produced by actuating the assembly, in particular the stream of first refrigerant, during operation in such a manner that the first refrigerant, along at least a section of the outside of the wall element containing the channel or channel system, forms a film of liquid, evaporating first refrigerant. Actuation of this nature is relatively easy to achieve in various ways for an average person skilled in the art.
• important factors include, inter alia: the velocity at which the gas which is to be cooled flows along the wall element, the temperature of the gas which is to be cooled; the physical properties of the gas; the amount of first refrigerant; the temperature of the first refrigerant; the physical properties of the first refrigerant; the physical properties of the wall element, etc.
• ammonia even a film thickness of less 200 micrometers, generally even less than 100 micrometers, has proven to the applicant to provide a sufficient isolating action.
• the isolating means may also comprise means which are permanently present, such as, according to the one of the preferred embodiments a partition which divides the gap running along the wall element which contains the channel or channel system into a first compartment, which adjoins the wall element, and a second compartment, which adjoins that side of the partition which faces away from the wall element, the gas which is to be cooled in this case being passed through the second compartment, while the first compartment, on account of the space between the partition and the wall element, has an isolating action.
• the multiplicity of plate-like wall elements comprises a multiplicity of pipes which are fitted into one another with cylindrical spaces between them, fomiing the gaps, the said opposite ends being the ends of the cylindrical gaps.
• the channel is a channel which runs helically through the wall of the said at least one pipe, or if the channel system is a system of channels running helically through the wall of the said at least one pipe. In this way, it is possible to achieve the effect of the heat transfer coefficient from the second refrigerant, which is to be cooled, to the film of first refrigerant is substantially equal to, or at least of the same order of magnitude as, the heat transfer from the gas which is to be cooled to the film of first ref ⁇ gerant.
• the multiplicity of pipes which have been fitted together comprises an outer pipe and a multiplicity of inner pipes, and if the channel or channel system of the refrigerant cooler is formed in at least one of the multiplicity of inner pipes.
• the channel or channel system of the refrigerant cooler is formed in one or more of the outer pipes of the multiplicity of inner pipes, preferably in the outermost pipe of the multiplicity of inner pipes.
• the isolating means comprise a partition which is formed on one side and/or the other side of the at least one wall element in which the channel or channel system of the refrigerant cooler is formed, the said partition divides the said gap into a first compartment on that side of the partition which faces towards the said at least one wall element and a second compartment on that side of the partition which faces away from the said at least one wall element, the first compartment, as seen in the direction of flow, being connected on the upstream side to the refrigerant inlet for admitting the first refrigerant to the gas cooler, the second compartment, as seen in the direction of flow, on the upstream side being connected to the gas inlet for gas which is to be cooled, and the first and second compartments, as seen in the direction of flow through them, on the downstream side preferably being in communication with one another, in order to allow the refrigerant to come into contact with the gas.
• the partition creates a separate space, which can be filled with gas and/or liquid from the second refrigerant, between the hot gas which is to be cooled and the wall element which contains the channel or channel system for second refrigerant.
• the partition according to the invention may extend through part of a gap or an entire gap or even entirely or partially on both sides of the wall element through which second refrigerant flows.
• the partition therefore has the task of preventing direct contact between the in particular hot gas which is to be cooled and the wall element through which the second refrigerant which is to be cooled is guided, and therefore of isolating the hot gas from the second refrigerant which is to be cooled.
• a second effect of the partition - which as such may also be considered entirely separately from the question of whether or not second refrigerant is flowing through the relevant wall element - is that subdividing the first gap, which adjoins the outer wall element, of the series of gaps into a first compartment, through which the first (or possibly only) refrigerant is guided, and a second compartment, which is adjacent (to the outermost wall element) and through which gas which is to be cooled is guided, prevents or at least counteracts sweating on the outside of the outer wall element, since this outer wall element will be heated by the warm/hot gas and is isolated from the first or only refrigerant used for cooling the gas by the space which results from the second compartment.
• the partition is made from a thermally conductive material, such as a metal sheet.
• the gaps of the series of gaps each have a substantially identical passage area.
• substantially identical passage area is not intended to mean that the passage areas per se must be of identical size, but rather that a slight margin, for example a range of 10 to 20% variation in the passage area, is possible.
• the present invention also relates to the use of an assembly according to the invention for cooling gaseous ammonia, in which the first refrigerant is ammonia, and preferably the second refrigerant is also ammonia.
• the first refrigerant is ammonia
• the second refrigerant is also ammonia.
• other refrigerants such as freon
• the invention also relates to the use of a gas cooler according to the invention for cooling gaseous ammonia, wherein the refrigerant is ammonia.
• other refrigerants, such as freon can also be used in the gas cooler according to the invention.
• the invention also relates to the use of an assembly according to the invention in a multistage cooling installation for cooling gas originating from the low-pressure side by the refrigerant, which originates from the high-pressure side and has been branched off, being injected into the said gas and for the main stream of refrigerant originating from the high-pressure side to be supercooled by means of the refrigerant which has been branched off from the high-pressure side.
• the invention also relates to the use of a gas cooler according to the invention in a multistage cooling installation for cooling gas originating from the low-pressure side by refrigerant originating from the high-pressure side being injected into it. Furthermore, according to the first aspect of the application, the invention also relates to a method for interstage cooling of gas originating from a low-pressure side and, cooling, preferably supercooling, liquid, or at least partially liquid, refrigerant originating from a high-pressure side, in a multistage cooling device, the refrigerant emanating from the high-pressure side being divided into a branch stream and a main stream, the main stream being passed through a channel or channel system formed in a wall element, the gas to be cooled being passed along the wall element, the branch stream being subjected to an expansion step and then being brought into contact with the wall element in such a manner that, along at least a section of the outside of the wall element, it forms a liquid film which isolates the wall element from the gas which is to be cooled.
• Fig. 1-3 show examples of two two-stage cooling devices as are known from the prior art.
• the combination of Fig. 1 with Fig. 2 has already been discussed, in particular in the introduction to the description.
• Fig. 1 to 3 will be briefly explained in more detail below, primarily by designation of the components.
• Fig. 1 shows a diagrammatic arrangement of a two-stage cooling installation in the general sense.
• the direction of flow through the various lines is in each case indicated more specifically by an arrow symbol.
• the two-stage cooling device comprises a so-called low-pressure side 1, referred to below as the "LP side", a high-pressure side 2, referred to below as the "HP side", and an interstage cooling unit 3 arranged between them.
• the LP side includes the evaporator 4, which is used to extract heat from the final consumer, or release cold to the final consumer, a control valve 5 of the throttle type, which is connected upstream of the evaporator, also known as a throttle control valve, and a compressor 6, which is connected downstream of the evaporator 4.
• the HP side 2 comprises a condenser 7, which dissipates the heat which has been absorbed substantially by the evaporator 4 to the environment, and a compressor 8, which is connected upstream of the condenser.
• Interstage cooling of the hot, gaseous refrigerant originating from the LP side, from line part 9, takes place between the LP side 1 and HP side 2 as a result of refrigerant, which has been branched off from the substantially liquid refrigerant originating from the high-pressure side (from line part 10) and is passed through an expansion valve 11, preferably a thermostatic expansion valve 11 (which is controlled by the pressures or temperatures measured at the sensor 12 via signal line 13), being injected and by the mixture then being allowed to exchange heat in a gas cooler 14 of the gap type having pipes which have been fitted into one another (cf.
• Fig. 4 diagrammatically depicts the outline circuit diagram of a two-stage cooling device as is substantially known from the prior art and is therefore substantially identical to Fig. 1 ;
• Fig. 5 diagrammatically depicts an interstage cooling device according to the first aspect of the application for a multistage cooling device according to the invention
• Fig. 6 diagrammatically depicts an interstage cooling device according to the second aspect of the application for a multistage cooling device according to the invention
• Fig. 7 diagrammatically depicts a longitudinal section through an assembly according to the invention as can be used in both the embodiment shown in Fig. 5 and in the embodiment shown in Fig. 6;
• Fig. 8 shows detail Vffl - VIII from Fig. 7, and
• Fig. 9 diagrammatically depicts a variant of an assembly according to the invention.
• the same reference numerals as in Fig. 1 are used for corresponding parts.
• the exception to this is that the interstage cooling device in Fig. 4 is denoted by 20.
• the refrigerant line which enters the HP side from the interstage cooling device 20 is denoted by 15, the refrigerant line which enters the LP side from the interstage cooling device 20 is denoted by 14, the refrigerant line which enters the interstage cooling device 20 from the LP side is denoted by 9, and the line which enters the interstage cooling device 20 from the HP side is denoted by 10.
• the interstage cooling device 20 may be configured with a refrigerant cooler or liquid supercooler (cf. Fig. 5) or without a refrigerant cooler or liquid supercooler (cf. Fig. 6).
• a refrigerant cooler or liquid supercooler cf. Fig. 5
• a refrigerant cooler or liquid supercooler cf. Fig. 6
• the assembly 30 according to the invention which is illustrated in more detail in Fig. 7 and substantially forms an integrated gas cooler/refrigerant cooler or gas cooler/liquid supercooler.
• the essential difference between the embodiment shown in Fig. 5 and that shown in Fig 6 is that in the embodiment shown in Fig. 6 the line parts 26 and 27 (Fig.
• Fig. 5 show an integrated gas cooler/refrigerant cooler assembly 30 according to the invention.
• the assembly 30 is composed of four pipes 44,
• the outer pipe 46 forms the outer shell, the external surface 47 of which is in contact with the environment.
• the inner pipes namely pipe 36, pipe 42 and pipe 44 in succession, are accommodated inside the outer shell 46.
• a space is left open between the outer shell and each of these pipes in order to form successive cylindrical gaps 32/34, 40 and 43.
• the pipes 46, 36, 42 and 44 form plate-like wall elements which delimit the gaps 32/34, 40 and 43.
• the gaps 32/34, 40 and 43 are each connected to their adjoining gap, to form a series of interconnected gaps.
• the gap 32/34 is subdivided by a cylindrical partition 33 into a first compartment 34, which adjoins pipe 36, and a second compartment 32, which adjoins the outer shell 46.
• the gas which is to be cooled can be passed into gap 32 via inlet 9 and the cylindrical distribution chamber 31. This gas which is to be cooled will then flow through the gap 32 to the end 39 (on the left in Fig. 7), in order, at the end 39 or space 39, to be, as it were, diverted through 180° and flow into gap 40, to flow through gap 40 towards the end 41 or space 41 (on the right on Fig.
• First refrigerant 22 can be supplied to the assembly via inlet 22 in order to cool the gas which is to be passed into the assembly via inlet 9.
• the first refrigerant 22 will enter the cylindrical distribution chamber 52 via inlet 22, in order to flow out of the cylindrical distribution chamber 52 into the first compartment 34 or gap 34, to flow through this gap 34 towards space 39 (on the left in Fig. 7), in order then to mix, in space 39, with the gas which is to be cooled and is passed via inlet 9 and gap 32 to space 39, and, together with this gas, to flow in succession via gap 40, space 41, gap
• the assembly will operate as follows: Via line 21, the stream of first refrigerant is branched off from the refrigerant steam which originates from the HP side via line 10 and will generally be liquid, but may also contain a gaseous component. This branched-off first refrigerant stream is fed, via line 21, to an expansion device 25 in the form of a thermostatic expansion valve which, via signal line 23 and sensor 24, is controlled on the basis of the temperature and or pressure in the gas outlet 15 of the interstage cooling device 20. As is known per se from the prior art, the setting of the thermostatic expansion valve 25 will generally be adapted so as to maintain a specific, desired temperature as accurately as possible in line 15.
• the expanded first refrigerant stream originating from expansion device 25 is fed to the assembly 30 via line 22 (referred to as inlet 22 in Fig. 7).
• Gas which is to be cooled is fed to the assembly 30 via line 9 (referred to as inlet 9 in Fig. 7).
• the gas which is to be cooled will heat the outer shell 46 and also the cylindrical partition 33. From the first compartment 34, the partition 33 will be cooled by first refrigerant which is flowing through this first compartment 34, and therefore the first refrigerant will absorb heat originating from the hot gas and will cool the hot gas.
• the aim will be for the partition 33 to be coated with a film of first refrigerant on its side which faces toward the first compartment 34, which film may, for example be less than 100 micrometers if ammonia is used as the first refrigerant.
• a film of this nature it is particularly important for the flow velocity of the first refrigerant in compartment 34 to be sufficiently high, for example to be in the range from 10 to 30 m s.
• Subdividing gap 32/34 (which according to the prior art is not subdivided into compartments) into a first and second compartment by means of partition 33 prevents the first refrigerant, which is used to cool the gas which is to be cooled, from being able to come in direct contact with the outer shell 46, thus preventing or at least substantially counteracting sweating or condensation on the outer surface 47 of the outer shell 46.
• the first refrigerant stream and the stream of gas which is to be cooled will converge in space 39, will mix with one another and will be guided onwards via gap 40 and gap 43, with the mixture in the meantime exchanging yet more heat in order, in this way, for the gas to be cooled further. If the system is set up correctly, by space 51 the first refrigerant stream will have become completely gaseous.
• the main stream of refrigerant originating from the HP side which remains after the first refrigerant stream has been branched off can be passed into the channel 50 via line 26 (Fig. 5) or inlet 26 (Fig. 7).
• Channel 50 is a helical channel which is formed in the wall of pipe 36 and, at the other end, opens out into an outlet 27, via which the cooled second refrigerant stream is discharged to the expansion valve 5 on the LP side.
• the helical channel 50 may be formed by milling a helical slot into a first pipe part 37 and then closing off this helical slot by sliding a close-fitting sleeve 38 over the first pipe part 37.
• the second refrigerant stream will release heat via pipe part 36 and sleeve 38 to the first refrigerant stream, which is colder in relative terms and is flowing through first compartment 34 or gap 34. In this way, the second refrigerant stream is cooled and, in practice, will even be supercooled.
• the partition 33 which divides gap 32/34 into a first compartment 34, through which the first refrigerant stream passes, and, in addition, a second compartment 32, through which the gas which is to be cooled passes, prevents the hot gas which is to be cooled from being able to come into direct contact with pipe 36, which would allow it to heat the second refrigerant stream instead of this second stream being cooled by the first refrigerant stream.
• the gas which is to be cooled will be cooled to a sufficient extent in space 39 to be able to be in direct contact with the pipe 36 in gap 40 without on balance heating the second refrigerant stream which is running through the helical channel 50.
• the medium mixture flowing through gap 40 will be able to partially heat the stream of second refrigerant, this heating will be less than the cooling effect via the other side of the pipe 36.
• Fig. 9 substantially represents a diagrammatic illustration of a gas cooler of the gap type composed of a multiplicity of flat plates or wall elements, namely outer plate 60, plate 64 which is provided with an internal channel 65, plate 70 and plate 73.
• a gap 61/63 which is subdivided into a first compartment 63 and a second compartment 61 by partition 62, is formed between outer wall plate 60 and plate 64.
• a gap 66/69 which is partially divided into a first compartment 66 and a second compartment 69 by a partition 68 is formed between plate 64 and plate 70.
• a gap 72 is formed between plates 70 and 73.
• Arrow 76 indicates the supply of gas which is to be cooled
• arrow 77 indicates the supply of the first refrigerant stream
• arrow 78 indicates the discharge of cooled gas.
• the supply and discharge for the second refrigerant stream, which open out into internal channel 65, are not shown.
• the assembly of pipes which have been fitted into one another which is illustrated in Fig. 7 it will be preferable for the assembly of pipes which have been fitted into one another which is illustrated in Fig. 7 to be arranged in horizontal or lying position. This is because the length of the assembly of pipes can be relatively long. If the gas to be cooled, the first refrigerant and the second refrigerant are ammonia, the following indicative values may be mentioned for the gaps: the passage area of the gaps may be up to approx. 10000 mm , with the following
• 9 7 values being mentioned by way of example: 650 mm , 1200 mm , 2200 mm , 3000 mm 2 , 4700 mm 2 and 8000 mm 2 . It will be attempted, in an assembly, to keep the passage areas of the gaps substantially equal to one another.
• the gap thicknesses it is possible to consider thicknesses ranging from 1 mm or less up to 25 mm, or possibly even above this, the following values being mentioned as examples of the gap thicknesses: 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 mm, as well as values between those listed. If the assembly according to the invention comprises a multiplicity of pipes which have been fitted into one another and a substantially constant value is desired for the passage area of the gaps of a single assembly, the gap thickness will increase from gap to gap from the outside inwards in the radial direction.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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• 1999
  • 1999-10-05 NL NL1013212A patent/NL1013212C2/nl not_active IP Right Cessation
• 2000
  • 2000-10-05 WO PCT/NL2000/000716 patent/WO2001035036A1/en not_active Application Discontinuation
  • 2000-10-05 EP EP00971887A patent/EP1218675A1/en not_active Withdrawn
  • 2000-10-05 AU AU10629/01A patent/AU1062901A/en not_active Abandoned
• 2002
  • 2002-04-05 ZA ZA200202691A patent/ZA200202691B/en unknown

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