CIRCULAR HEAT EXCHANGER AND METHOD

Description

[0001] The invention relates to a wound heat exchanger and a method for exchanging heat between a refrigerant and a medium using such a wound heat exchanger.

[0002] Liquefied natural gas (LNG) is the term used to describe processed natural gas that has been liquefied by cooling it to between -161 °C and -164 °C. LNG has only a fraction of the volume of gaseous natural gas. This makes it particularly advantageous for transportation and storage purposes. LNG can be transported as a liquid in suitable containers by road, rail, or water.

[0003] According to internal experience, coil-wound heat exchangers (CWHE) or coil-wound heat exchangers can be used to liquefy natural gas. Such a coil-wound heat exchanger comprises a shell and a tube bundle housed in the shell, through which the natural gas to be liquefied is passed. The tube bundle is sprayed with a liquid phase of a two-phase refrigerant, for example, using a so-called ring-channel distributor. Examples of ring-channel distributors are shown in the documents DE 10 2011 017030 A1, WO 2006 / 021315 A1, and DE 10 2011 103583 A1.

[0004] Such an annular channel distributor comprises an annular channel encircling the inside of the shell and distributors extending radially out of the annular channel, which distribute the liquid phase evenly across the tube bundle. Between the distributors, tubes, called braids, of the tube bundle are guided upwards past the annular channel distributor to a tube sheet. The higher the annular channel, the further the tube sheet is spaced from the tube bundle, and the longer the tubes leading to the tube sheet must be. This can complicate the production of the wound heat exchanger. This needs to be improved.

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

[0006] Accordingly, a wound heat exchanger for exchanging heat between a refrigerant and a medium is proposed.The wound heat exchanger comprises a shell, a tube bundle arranged within the shell through which the medium can flow, a first annular channel arranged within the shell and encircling the same for separating a liquid phase of the refrigerant from a gaseous phase of the refrigerant, a second annular channel arranged within the shell and encircling the same for evenly distributing the liquid phase over the tube bundle in order to exchange heat between the refrigerant and the medium, and a connecting channel which establishes a fluid connection between the first annular channel and the second annular channel in order to conduct the liquid phase from the first annular channel into the second annular channel, wherein the first annular channel and the second annular channel are arranged at a distance from one another as viewed along an axis of symmetry of the shell.

[0007] By providing a first annular channel and a second annular channel separated from the first annular channel, it is possible to design the first annular channel and the second annular channel with different widths. This simplifies manufacturing and can also lead to a reduction in the buildup of the liquid phase in the annular channels. Furthermore, the first annular channel can be used to pre-separate the liquid and gaseous phases of the refrigerant.

[0008] The wound heat exchanger is in particular a so-called coil wound heat exchanger (CWHE). The wound heat exchanger is preferably suitable for liquefying natural gas. This means that the medium can be natural gas. However, the wound heat exchanger can also be used for liquefying any media other than natural gas. The tube bundle is wound in particular in multiple layers onto a core tube arranged centrally in the shell. The shell preferably comprises a hollow cylindrical base section, which can be constructed rotationally symmetrically to the axis of symmetry, a cover section that closes off the base section at the top, and a base section that closes off the base section at the bottom. The axis of symmetry can also be referred to as the central axis. The shell is in particular fluid-tight.

[0009] The tube bundle comprises a tube side and a shell side. The "tube side" in this case refers to an interior space enclosed by tubes of the tube bundle, through which the medium to be liquefied is passed. The medium is thus fed into the tubes of the tube bundle. "Feeding" the medium into the tube bundle specifically means introducing the medium into the tubes of the tube bundle. On the tube side, several different fractions or pipe streams can flow through the tube bundle. One of the fractions can be the medium. Another of the fractions can be part of the refrigerant. Further fractions can include, for example, other refrigerants, process media, or the like.

[0010] This means that the refrigerant can also be fed into the tube bundle and passed through the tube bundle on the tube side. However, direct contact and thus no mixing of the fractions within the tube bundle is possible. The tube bundle thus comprises tubes through which only the medium flows. Other tubes are only flowed through by the refrigerant. Furthermore, additional tubes can be provided through which other fractions flow. The aforementioned different tubes can form different layers of the tube bundle.

[0011] In this context, "shell-side" refers to an area outside the tubes of the tube bundle. On the shell side, the refrigerant flows through the tube bundle. A multitude of gaps or passages lead through the tube bundle, through which the refrigerant is conducted to extract heat from the tube bundle, particularly from the medium. During the heat exchange between the refrigerant and the medium, heat is preferably extracted from the medium, which is absorbed by the refrigerant. In the process, the refrigerant can at least partially evaporate. The refrigerant can also evaporate completely. After flowing around or through the tube bundle on the shell side, the completely or partially evaporated refrigerant can be extracted from the shell.

[0012] The refrigerant can be ethane, for example. However, any other refrigerant can also be used. A refrigerant is suitable for transporting enthalpy from a material to be cooled, in this case the medium, to its surroundings. The difference to a cooling agent is that a refrigerant can carry out this heat transport in a refrigeration circuit along a temperature gradient, so that with the expenditure of added energy, the ambient temperature can even be higher than the temperature of the medium to be cooled, whereas a cooling agent is only capable of transporting the enthalpy in a cooling circuit against the temperature gradient to a point of lower temperature. By removing heat from the medium, it is liquefied. In the case of natural gas, the liquefied medium or natural gas can be referred to as liquefied natural gas (LNG).

[0013] The first annular channel can also be referred to as the upper annular channel, as it is arranged above the second annular channel with respect to the direction of gravity. Accordingly, the second annular channel can be referred to as the lower annular channel. The fact that the first annular channel "circulates" around the casing means, in this case, that the first annular channel preferably completely surrounds the axis of symmetry, thus forming an annular geometry. The first annular channel can be continuous. Alternatively, it is also possible for the first annular channel to be divided into several separate annular segments. The same applies to the second annular channel. The first annular channel and the second annular channel are two separate components that are arranged at a certain distance from each other when viewed along the axis of symmetry.

[0014] The connecting channel can be a pipe, a shaft, a hose, or the like. The connecting channel guides the liquid medium from the first annular channel into the second annular channel. The connecting channel is a downpipe or can be referred to as a downpipe. Any number of connecting channels can be provided. The connecting channel can have a circular or any other cross-section.

[0015] The second annular channel is designed to evenly distribute the liquid phase of the refrigerant across the tube bundle. For this purpose, the second annular channel can comprise distributors, which will be explained later. These distributors are, in particular, part of the second annular channel. Furthermore, the second annular channel itself can also have openings, bores, or the like that allow the tube bundle to be evenly sprayed with the liquid phase of the refrigerant. The second annular channel can also be referred to as an annular channel distributor.

[0016] The first annular channel is suitable for separating the liquid phase of the refrigerant from the gaseous phase of the refrigerant. Separation occurs when the liquid phase is drawn downwards towards the second annular channel using the connecting channel, and the gaseous phase of the refrigerant exits upwards from the first annular channel. This means that the refrigerant is two-phase and can have a liquid phase and a gaseous phase. The liquid phase can transition into the gaseous phase and vice versa. In particular, the liquid phase of the refrigerant transitions at least partially from the liquid phase to the gaseous phase as it flows through or around the tube bundle. In the process, the evaporating refrigerant absorbs heat from the medium.

[0017] According to one embodiment, the second annular channel comprises a plurality of distributors for uniformly distributing the liquid phase onto the tube bundle, wherein the distributors project radially further into the shell toward the axis of symmetry than the second annular channel.

[0018] The number of distributors is fundamentally arbitrary. For example, three or six distributors are provided. The distributors are positioned at equal distances from one another around the axis of symmetry. The distributors extend radially from the second annular channel into the shell, thus partially covering the tube bundle from above. The distributors are, in particular, part of the second annular channel and are in fluid communication with it. In this case, the fact that the distributors are "in fluid communication" with the second annular channel means, in particular, that the liquid phase of the refrigerant can flow from the second annular channel into the distributors. The distributors preferably each have a plurality of openings, apertures, bores, or the like arranged on the underside, which enable the tube bundle to be evenly sprayed with the liquid phase of the refrigerant.

[0019] According to a further embodiment, the distributors are arranged evenly distributed around the axis of symmetry, with a space being provided between each two adjacent distributors.

[0020] The number of spaces preferably corresponds to the number of distributors. In particular, the distributors and spaces are arranged alternately, so that there is a space between two distributors and a distributor between two spaces.

[0021] According to a further embodiment, the wound heat exchanger further comprises a plurality of connecting channels, wherein each distributor is assigned a connecting channel.

[0022] This means, in particular, that the number of distributors and the number of connecting channels are the same. For example, three or six connecting channels are provided.

[0023] According to a further embodiment, the connecting channel runs parallel to the axis of symmetry.

[0024] In particular, the connecting channel runs along the direction of gravity. By arranging the connecting channel(s) parallel to the axis of symmetry, the shortest possible connection between the first annular channel and the second annular channel can be achieved. In particular, the connecting channels open out of a base of the first annular channel.

[0025] According to a further embodiment, the first annular channel and the second annular channel project radially into the shell to different extents toward the axis of symmetry.

[0026] In particular, the first annular channel and the second annular channel extend radially to different distances into an interior space enclosed by the casing. The first annular channel has a first inner diameter. The second annular channel has a second inner diameter. The inner diameters can be different sizes, so that the first annular channel and the second annular channel extend into the casing to different distances. Alternatively, the first inner diameter of the first annular channel and the second inner diameter of the second annular channel can also be the same size.

[0027] According to a further embodiment, the second annular channel projects radially towards the axis of symmetry further into the casing than the first annular channel.

[0028] In particular, this means that the second annular channel is wider than the first. This facilitates the production of the wound heat exchanger.

[0029] According to a further embodiment, the first annular channel is arranged above the second annular channel when viewed along a direction of gravity.

[0030] As mentioned previously, the first annular channel can therefore also be referred to as the upper annular channel and the second annular channel as the lower annular channel. The second annular channel is located below the first annular channel, viewed along the direction of gravity.

[0031] According to a further embodiment, the wound heat exchanger further comprises a tube sheet which is in fluid communication with tubes of the tube bundle, wherein the tube sheet is arranged between the first annular channel and the second annular channel as viewed along the axis of symmetry.

[0032] In particular, the tubesheet is positioned below the first annular channel and above the second annular channel, viewed along the direction of gravity. Multiple tubesheets can be provided. Preferably, the number of tubesheets corresponds to the number of distributors. Twice as many tubesheets as distributors can also be provided. By arranging the tubesheet between the first annular channel and the second annular channel, it is possible to shorten the tubes drawn upward from the tube bundle compared to a coiled heat exchanger with only one annular channel. This facilitates the manufacturability of the coiled heat exchanger. The upwardly drawn tubes can also be referred to as "braids." This makes it possible to reduce the "braid length."

[0033] According to a further embodiment, the first annular channel and / or the second annular channel each run completely around the axis of symmetry.

[0034] This means that the first ring channel and / or the second ring channel each have a circumferential angle of 360°. However, as previously mentioned, it is also possible for the first ring channel and / or the second ring channel to be divided into several separate ring channel segments.

[0035] According to a further embodiment, the first annular channel and / or the second annular channel are each open in the direction of a cover section of the casing.

[0036] In particular, the first annular channel and / or the second annular channel are open at the top. This allows the gaseous phase of the refrigerant to escape upwards from the respective annular channel.

[0037] Furthermore, a method for exchanging heat between a refrigerant and a medium using such a wound heat exchanger is proposed. The heat exchanger comprises a shell, a tube bundle arranged within the shell, a first annular channel arranged within and encircling the shell, a second annular channel arranged within and encircling the shell, and a connecting channel that establishes a fluid connection between the first annular channel and the second annular channel. The first annular channel and the second annular channel are arranged spaced apart from one another along an axis of symmetry of the shell.The method comprises the following steps: a) flowing the medium through the tube bundle, b) separating a liquid phase of the refrigerant from a gaseous phase of the refrigerant by means of the first annular channel, c) directing the liquid phase into the second annular channel by means of the connecting channel, and d) evenly distributing the liquid phase over the tube bundle by means of the second annular channel in order to exchange heat between the refrigerant and the medium.

[0038] Steps a) to d) can be performed simultaneously. In particular, during step d), heat is extracted from the medium with the aid of the refrigerant. The refrigerant can at least partially evaporate and enter the gaseous phase. The medium can be liquefied or at least cooled. The medium flows through the tube bundle, particularly on the tube side. The liquid phase is distributed over the tube bundle, particularly on the shell side.

[0039] According to one embodiment, in step d) the liquid phase is distributed evenly over the tube bundle by means of several distributors of the second annular channel.

[0040] The number of distributors is, in principle, unlimited. By providing multiple distributors, a particularly uniform distribution of the liquid phase can be achieved. The distributors are preferably part of the second annular channel.

[0041] According to a further embodiment, in step d), the liquid phase is dammed up in the second annular channel in such a way that the connecting channel opens into the second annular channel below a liquid level of the liquid phase in the latter.

[0042] In particular, a lower edge of the connecting channel is located below the liquid level. The connecting channel is thus immersed or submerged in the liquid phase.

[0043] According to a further embodiment, in step b), the liquid phase is withdrawn downwards from the first annular channel with the aid of the connecting channel, viewed along a direction of gravity, wherein the gaseous phase exits upwards from the first annular channel, viewed along the direction of gravity.

[0044] The gaseous phase can be extracted from the shell at the cover section. The liquid phase of the refrigerant that has not evaporated and is escaping downwards from the tube bundle can also be extracted from the shell.

[0045] The embodiments and features described for the proposed wound heat exchanger apply accordingly to the proposed method and vice versa.

[0046] "One" in this case is not necessarily to be understood as limiting the number to exactly one element. Rather, multiple elements, such as two, three, or more, can also be considered. Any other counting term used here should also not be understood as requiring a precise limitation to the corresponding number of elements. Rather, numerical deviations upwards and downwards are possible.

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

[0048] Further advantageous embodiments of the wound heat exchanger and / or the method are the subject of the dependent claims and the exemplary embodiments of the wound heat exchanger and / or the method described below. The wound heat exchanger and / or the method are explained in more detail below using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a schematic sectional view of an embodiment of a wound heat exchanger; Fig. 2 shows a further schematic sectional view of the wound heat exchanger according to the section line II-II of the Fig. 1 ; and Fig. 3 shows a schematic block diagram of an embodiment of a method for exchanging heat between a refrigerant and a medium using the wound heat exchanger according to Fig. 1 .

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

[0050] The Fig. 1 shows a schematic sectional view of an embodiment of a coil wound heat exchanger 1 (CWHE). Fig. 2 shows a schematic sectional view of the wound heat exchanger 1. The following refers to the Fig. 1 and 2 referred to at the same time.

[0051] Such a coiled heat exchanger 1 can be used for liquefying natural gas (LNG). However, other gases can also be liquefied. The coiled heat exchanger 1 will be referred to simply as a heat exchanger below.

[0052] The heat exchanger 1 comprises a shell 2. The shell 2 is constructed from a cylindrical base section 3, a dome-shaped, curved cover section 4, and a dome-shaped, curved base section (not shown). With respect to a direction of gravity g, the cover section 4 is positioned above the base section. For example, the base section 3, the cover section 4, and the base section are soldered, welded, screwed, or riveted together.

[0053] The casing 2 is fluid-tight. The casing 2 encloses an interior space 5. The casing 2 can be made of an aluminum alloy or a steel alloy. The casing 2 is essentially rotationally symmetrical about a central or symmetry axis 6. "Essentially" means that the casing 2 does not necessarily have to have a circular cross-section. The casing 2 can also be slightly oval or elliptical in cross-section. The casing 2 is positioned upright or vertically. This means that the axis of symmetry 6 runs parallel to the direction of gravity g.

[0054] Heat exchanger 1 is assigned a coordinate system with a width direction or x-direction x, a height direction or y-direction y, and a depth direction or z-direction z. The directions x, y, and z are oriented perpendicular to each other. The z-direction z is oriented parallel to the direction of gravity g and parallel to the axis of symmetry 6.

[0055] An inlet nozzle 7 is provided on the base section 3, which is oriented perpendicular to the axis of symmetry 6. A refrigerant K, for example, ethane, can be supplied to the heat exchanger 1 via the inlet nozzle 7. The refrigerant K can be two-phase, so that it has a liquid phase KL and a gaseous phase KG. Multiple inlet nozzles 7 can be provided.

[0056] The refrigerant K is in the Fig. 1 and 2 represented by block arrows. Block arrows with diagonal hatching represent a two-phase state of the refrigerant K. Horizontally hatched block arrows represent the gaseous phase KG of the refrigerant K. Unhatched block arrows represent the liquid phase KL of the refrigerant K.

[0057] The refrigerant K can be fed into an upper or first annular channel 8 via the inlet connection 7. The first annular channel 8 can be rectangular in cross-section. The first annular channel 8 is arranged within the shell 2. The first annular channel 8 runs completely around the axis of symmetry 6, so that the first annular channel 8 has a closed annular geometry. In principle, however, the first annular channel 8 can also be divided into several annular segments. The first annular channel 8 has an inner diameter d8.

[0058] The first annular channel 8 is open upwards, i.e., in the direction of the cover section 4, so that the gaseous phase KG can exit the first annular channel 8 upwards, counter to the direction of gravity g. The gaseous phase KG can be withdrawn from the casing 2, for example, using an outlet nozzle provided on the cover section 4. Alternatively, the gaseous phase KG can be withdrawn downwards together with the liquid phase KL. The first annular channel 8 projects radially, i.e., in the direction toward the axis of symmetry 6, into the casing 2, in particular into the interior space 5.

[0059] A liquid level 9 of the liquid phase KL is established in the first annular channel 8. The first annular channel 8 serves to separate the gaseous phase KG from the liquid phase KL. Separation occurs by allowing the gaseous phase KG, as previously mentioned, to escape upwards from the first annular channel 8, and by withdrawing the liquid phase KL downwards, i.e., in the direction of gravity g, from the first annular channel 8 by means of a connecting channel 10.

[0060] The connecting channel 10 runs parallel to the direction of gravity g or parallel to the axis of symmetry 6. The connecting channel 10 can be a shaft, a pipe, or the like. Preferably, several connecting channels 10 to 12 are provided. The number of connecting channels 10 to 12 is fundamentally arbitrary. For example, three or six connecting channels 10 to 12 are provided. The connecting channels 10 to 12 are arranged evenly distributed around the axis of symmetry 6. However, only one connecting channel 10 will be discussed below.

[0061] The connecting channel 10 conducts the liquid phase KL from the first annular channel 8 into a lower or second annular channel 13. Viewed along the axis of symmetry 6, the second annular channel 13 is arranged at a distance from the first annular channel 8. Viewed along the direction of gravity g, the first annular channel 8 is positioned above the second annular channel 13, and the second annular channel 13 is positioned below the first annular channel 8.

[0062] The second annular channel 13, like the first annular channel 8, can be rectangular in cross-section. The second annular channel 13 is arranged within the casing 2. The second annular channel 13 runs completely around the axis of symmetry 6, so that the second annular channel 13 has a closed annular geometry. In principle, however, the second annular channel 13 can also be divided into several annular segments. The second annular channel 13 has an inner diameter d13. The inner diameter d13 can be smaller than the inner diameter d8. Alternatively, the inner diameters d8 and d13 can also be the same size. Furthermore, the inner diameter d8 can also be smaller than the inner diameter d13.

[0063] The second annular channel 13 is open upwards, i.e., toward the cover section 4, so that the gaseous phase KG can exit upwards from the second annular channel 13 against the direction of gravity g. The second annular channel 13 projects radially, i.e., toward the axis of symmetry 6, into the shell 2, in particular into the interior space 5. The second annular channel 13 preferably projects further into the shell 2 than the first annular channel 8.

[0064] A liquid level 14 of the liquid phase KL is established in the second annular channel 13. The connecting channel 10 is immersed in the liquid phase, so that a lower edge of the connecting channel 10, viewed along the direction of gravity g, is positioned below the liquid level 14. The second annular channel 13 serves to evenly distribute the liquid phase KL among several distributors 15 to 17. The distributors 15 to 17 are part of the second annular channel 13.

[0065] The number of distributors 15 to 17 is arbitrary. For example, three or six distributors 15 to 17 are provided. Preferably, the number of distributors 15 to 17 corresponds to the number of connecting channels 10 to 12. Each distributor 15 to 17 can be assigned a connecting channel 10 to 12. The distributors 15 to 17 are arranged evenly distributed around the axis of symmetry 6 or around a circumference of the casing 2.

[0066] The distributors 15 to 17 can be designed as ring segments. However, this is not mandatory. A "ring segment" is understood here to mean a section of a ring. The distributors 15 to 17 are arranged alternately with spaces 18 to 20. This means that between two adjacent distributors 15 to 17, a space 18 to 20 is arranged, and between two spaces 18 to 20, a distributor 15 to 17 is arranged. Only one distributor 15 will be discussed below.

[0067] The distributor 15 extends radially in the direction of the axis of symmetry 6 further into the casing 2, in particular into the interior space 5, than the second annular channel 13. The distributor 15 is in fluid communication with the second annular channel 13. "Fluid communication" in this case means, in particular, that the liquid phase KL can flow from the second annular channel 13 into the distributor 15. For this purpose, a breakthrough, an opening, or the like can be provided, for example, in a base of the second annular channel 13.

[0068] The distributor 15 is closed at the top, i.e., toward the cover section 4. The liquid phase KL can exit the distributor 15 at the bottom, i.e., away from the cover section 4. For this purpose, the distributor 15 has a plurality of outlet openings, apertures, bores, or the like on its underside, with the aid of which the liquid phase KL can be evenly distributed.

[0069] The heat exchanger 1 further comprises a tube bundle 21 arranged within the shell 2, which is sprayed with the liquid phase KL by means of the distributors 15 to 17. The liquid phase KL is evaporated, in particular, by means of a falling film. The tube bundle 21 is wound onto a core tube 22 located centrally in the shell 2. The tube bundle 21 comprises a plurality of tubes wound in multiple layers onto the core tube 22. The tube bundle 21 includes slots or gaps so that the liquid phase KL can flow through the tube bundle 21 on the shell side. "Shell side" is understood here to mean an area outside the tubes of the tube bundle 21. The tube bundle 21 completely fills an annular gap 23 provided between the core tube 22 and the shell 2.

[0070] On the tube side, several different fractions or pipe streams can be passed through the tube bundle 21. One of the fractions can be a medium to be liquefied, for example, natural gas. Another of the fractions can be the liquid phase KL of the refrigerant K. Further fractions can include, for example, other refrigerants, process media, or the like. This means that the refrigerant K can also be fed into the tube bundle 21 and passed through the tube bundle 21 on the tube side. However, direct contact and thus mixing of the fractions in the tube bundle 21 is not possible.

[0071] The tube bundle 21 thus comprises tubes through which only the medium flows. Further tubes are only flowed through by the refrigerant K. Furthermore, additional tubes can be provided through which other fractions flow. The aforementioned different tubes can form different layers of the tube bundle 21. The "tube side" is understood here to mean an interior space enclosed by the tubes of the tube bundle 21, through which the medium to be liquefied, the refrigerant K, and / or other fractions are passed.

[0072] Individual tubes 24 to 26 are drawn from the tube bundle 21 through the gaps 18 to 20 upwards toward the cover section 4. The tubes 24 to 26 run parallel to the axis of symmetry 6. The tubes 24 to 26 can also be referred to as "braids." The tubes 24 to 26 are fed to a tube plate 27. Preferably, several tube plates 27 to 29 are provided. The number of tube plates 27 to 29 can correspond to the number of distributors 15 to 17. However, this is not mandatory. For example, twice as many tube plates 27 to 29 as distributors 15 to 17 can be provided.

[0073] Viewed along the axis of symmetry 6, the tube sheets 27 to 29 can be positioned at different heights. This means that the tube sheets 27 to 29 can be offset from one another along the axis of symmetry 6. However, the tube sheets 27 to 29 can also all be arranged at the same height. The tube sheets 27 to 29 can be assigned to different tube streams or fractions of the tube bundle 21.

[0074] The tube sheets 27 to 29 are welded or soldered into the shell 2. The tube sheets 27 to 29 can also be connected to the shell 2 by means of nozzles (not shown). The tube sheets 27 to 29 can be arranged evenly distributed around the axis of symmetry 6. However, this is not absolutely necessary. The tube sheets 27 to 29 can also be arranged unevenly distributed around the axis of symmetry 6. At least one tube sheet 27 to 29 can be assigned to each intermediate space 18 to 20. However, this is not absolutely necessary. Only one tube sheet 27 will be discussed below.

[0075] The tube sheet 27 is fluidly connected to the inlet nozzle 7 via a supply line 30 and an expansion valve 31. In particular, tubes of the tube bundle 21, through which the refrigerant K is conducted on the tube side, are fluidly connected to the inlet nozzle 7 via the tube sheet 27 and the supply line 30. The expansion valve 31 is a so-called Joule-Thomson valve. The coolant K flowing through the tube bundle 21 is returned to the inlet nozzle 7 via the supply line 30. This coolant K is under a higher pressure than the interior space 5 of the shell 2. The refrigerant K is expanded in the expansion valve 31 and fed to the inlet nozzle 7 as a two-phase flow. During the expansion, expansion cooling is created, which cools the refrigerant K. This "colder" refrigerant K is then used to cool the tube bundle 21 again.

[0076] The tubes 24 to 26 are in fluid communication with the tubesheet 27. The tubesheet 27 is positioned between the first annular channel 8 and the second annular channel 13, viewed along the axis of symmetry 6. In particular, the tubesheet 27 is positioned below the first annular channel 8 and above the second annular channel 13.

[0077] This makes it possible to shorten the length of tubes 24 to 26 compared to a heat exchanger with only one annular channel. This simplifies the manufacturability of heat exchanger 1. Furthermore, by providing two separate annular channels 8, 13, it is possible to design the annular channels 8, 13 with different widths. This simplifies production and can also lead to a reduction in the buildup of the liquid phase KL in the annular channels 8, 13.

[0078] The functionality of heat exchanger 1 is explained below. The medium to be liquefied flows through tube bundle 21 on the tube side. The two-phase refrigerant K is fed to the first annular channel 8 via the inlet nozzle 7. In the first annular channel 8, the liquid phase KL is separated from the gaseous phase KG by drawing the liquid phase KL downwards into the second annular channel 13 with the help of the connecting channels 10 to 12, and the gaseous phase KG escaping upwards. The gaseous phase KG can be drawn upwards or downwards. For example, the gaseous phase KG can be drawn downwards together with the liquid phase KL via the tube bundle 21.

[0079] The second annular channel 13 distributes the liquid phase KL evenly among the distributors 15 to 17, which in turn spray the tube bundle 21 with the liquid phase KL. The liquid phase KL flows through the shell side of the tube bundle 21, whereby the liquid phase KL at least partially evaporates. In the process, heat is extracted from the medium. The medium liquefies in the process. The evaporated liquid phase KL rises upwards as the gaseous phase KG and can be withdrawn upwards. Alternatively, the gaseous phase KG can also be withdrawn downwards through the tube bundle 21. The liquid phase KL that does not evaporate flows out of the bottom of the tube bundle 21 and can be withdrawn downwards.

[0080] The Fig. 3shows a schematic block diagram of an embodiment of a method for exchanging heat between the refrigerant K and the medium using the coiled heat exchanger 1. In a step S1, the medium flows through the tube bundle 21. In a step S2, the liquid phase KL of the refrigerant K is separated from the gaseous phase KG using the first annular channel 8.

[0081] In a step S3, the liquid phase KL is directed into the second annular channel 13 via the connecting channels 10 to 12. In a step S4, the liquid phase KL is evenly distributed over the tube bundle 21 via the distributors 15 to 17 to exchange heat between the refrigerant K and the medium. Steps S1 to S4 can be performed simultaneously.

[0082] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. Reference symbols used

[0083] 1Heat exchanger 2Shell 3Base section 4Cover section 5Interior 6Symmetry axis 7Inlet nozzle 8Annular channel 9Liquid level 10Connecting channel 11Connecting channel 12Connecting channel 13Annular channel 14Liquid level 15Distributor 16Distributor 17Distributor 18Intermediate space 19Intermediate space 20Intermediate space 21Tube bundle 22Core tube 23Annular gap 24Tube 25Tube 26Tube 27Tube sheet 28Tube sheet 29Tube sheet 30Feed line 31Relief valve d8Inner diameter d13Inner diameter gDirection of gravity KRefrigerant KGGaseous phase KLiquid phase S1Step S2Step S3Step S4Step xx-direction yy-direction zz-direction

Claims

1. Wound heat exchanger (1) for the exchange of heat between a refrigerant (K) and a medium, comprising a shell (2), a bundle of tubes (21) which is arranged inside the shell (2) and through which the medium can flow, a first annular channel (8) which is arranged inside the shell (2) and runs around it and is intended for separating a liquid phase (KL) of the refrigerant (K) from a gaseous phase (KG) of the refrigerant (K), a second annular channel (13) which is arranged inside the shell (2) and runs around it and is intended for evenly distributing the liquid phase (KL) over the bundle of tubes (21) in order to exchange the heat between the refrigerant (K) and the medium, and a connecting channel (10-12) which establishes a fluid connection between the first annular channel (8) and the second annular channel (13) in order to conduct the liquid phase (KL) out of the first annular channel (8) into the second annular channel (13), wherein the first annular channel (8) and the second annular channel (13) are spaced apart from one another when viewed along an axis of symmetry (6) of the shell (2).

2. Wound heat exchanger according to claim 1, wherein the second annular channel (13) comprises a plurality of distributors (15-17) for evenly distributing the liquid phase (KL) over the bundle of tubes (21), and wherein the distributors (15-17) protrude radially toward the axis of symmetry (6) further into the shell (2) than the second annular channel (13).

3. Wound heat exchanger according to claim 2, wherein the distributors (15-17) are evenly distributed around the axis of symmetry (6), and wherein an intermediate space (18-20) is provided between two adjacent distributors (15-17) in each case.

4. Wound heat exchanger according to either claim 2 or claim 3, further comprising a plurality of connecting channels (10-12), wherein a connecting channel (10-12) is associated with each distributor (15-17).

5. Wound heat exchanger according to any of claims 1 to 4, wherein the connecting channel (10-12) runs in parallel with the axis of symmetry (6).

6. Wound heat exchanger according to any of claims 1 to 5, wherein the first annular channel (8) and the second annular channel (13) protrude radially toward the axis of symmetry (6) to different extents into the shell (2).

7. Wound heat exchanger according to claim 6, wherein the second annular channel (13) protrudes radially toward the axis of symmetry (6) further into the shell (2) than the first annular channel (8).

8. Wound heat exchanger according to any of claims 1 to 7, wherein the first annular channel (8) is arranged above the second annular channel (13) when viewed along a direction of gravity (g).

9. Wound heat exchanger according to any of claims 1 to 8, further comprising a tube sheet (27-29) which is in fluid connection with tubes (24-26) of the bundle of tubes (21), and wherein the tube sheet (27-29) is arranged between the first annular channel (8) and the second annular channel (13) when viewed along the axis of symmetry (6).

10. Wound heat exchanger according to any of claims 1 to 9, wherein the first annular channel (8) and / or the second annular channel (13) each run completely around the axis of symmetry (6).

11. Wound heat exchanger according to any of claims 1 to 10, wherein the first annular channel (8) and / or the second annular channel (13) are each open in the direction of a cover portion (4) of the shell (2).

12. Method for the exchange of heat between a refrigerant (K) and a medium with the aid of a wound heat exchanger (1), which comprises a shell (2), a bundle of tubes (21) which is arranged inside the shell (2), a first annular channel (8) which is arranged inside the shell (2) and runs around it, a second annular channel (13) which is arranged inside the shell (2) and runs around it, and a connecting channel (10-12) which establishes a fluid connection between the first annular channel (8) and the second annular channel (13), wherein the first annular channel (8) and the second annular channel (13) are spaced apart from one another when viewed along an axis of symmetry (6) of the shell (2), comprising the following steps: a) the medium flowing (S1) through the bundle of tubes (21), b) separating (S2) a liquid phase (KL) of the refrigerant (K) from a gaseous phase (KG) of the refrigerant (K) with the aid of the first annular channel (8), c) conducting (S3) the liquid phase (KL) into the second annular channel (13) with the aid of the connecting channel (10-12), and d) evenly distributing (S4) the liquid phase (KL) over the bundle of tubes (21) with the aid of the second annular channel (13) in order to exchange the heat between the refrigerant (K) and the medium.

13. Method according to claim 12, wherein, in step d), the liquid phase (KL) is evenly distributed over the bundle of tubes (21) with the aid of a plurality of distributors (15-17) of the second annular channel (13).

14. Method according to either claim 12 or claim 13, wherein, in step d), the liquid phase (KL) is accumulated in the second annular channel (13) such that the connecting channel (10-12) opens into the second annular channel (13) below a liquid level (14) of the liquid phase (KL) in the second annular channel.

15. Method according to any of claims 12 to 14, wherein, in step b), the liquid phase (KL), when viewed along a direction of gravity (g), is drawn off downward from the first annular channel (8) with the aid of the connecting channel (10-12), and wherein the gaseous phase (KG) emerges upward from the first annular channel (8) when viewed along the direction of gravity (g).