EP3159648B1 - Plate heat exchanger capacitor evaporator and method for cryogenic decomposition of air - Google Patents

Description

The invention relates to a plate heat exchanger condenser evaporator and a method for the cryogenic separation of air according to the preambles of the independent claims.

State of the art

EP 0952419 A1 describes such a plate heat exchanger condenser evaporator and a corresponding method.

In air separation plants combined evaporation and condensation units can be used for different purposes, among other things as main condensers or as overhead condensers of (raw) argon columns.

Like for example H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH, Weinheim: 2006, in Section 2.2.5.6, "Apparatus" or the subsection "Combined Evaporator / Condenser-Heat Transfer Units" on page 52 and 53 These are typically special types of plate heat exchangers (Plate Fin Heat Exchangers). Hereinafter, the term plate heat exchanger condenser evaporator is therefore used for such units.

With regard to the expert understanding of the terms used in the following elements, reference is made in particular to the publication " The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturers' Association, 2nd Edition, 2000, especially Section 1.2.1, "Components of an Exchanger (hereafter referred to as "ALPEMA Standards").

A plate heat exchanger condenser evaporator, as it is based on the present invention, has a number of superimposed heat exchanger plates which form a, usually cuboid, heat exchanger block (block, core). Each of the heat exchanger plates usually has an embossed sheet with heat transfer fins in its central area. The heat exchange ribs, for example, straight (plain fins) and possibly perforated (engl. Plain-perforated fins), but also interrupted and
Serrated Fins), wavy (English: Herringbone Fins) or be formed in another way.

The embossed sheet is surrounded by a border of side elements (English Side Bars). The embossed sheets and side elements of the individual heat exchanger plates are separated by flat sheets (English Parting Sheets). The top and bottom heat exchanger plates each have a cover plate (English: Cap Sheet). The heat exchange ribs and possibly existing fluid distribution and fluid collection structures (see below) of each heat exchanger plate thereby define "fluid guidance structures" in the language used here.

In a plate heat exchanger condenser evaporator conventional type, the fluid guide means terminate a first group of the heat exchanger plates at first and second outer surfaces of the heat exchanger block, the first and second outer surfaces being opposite and parallel to each other. According to its function, the first outer surface is also referred to as the "exit surface" and the second outer surface as the "suction surface" for fluid. The fluid guides of the first heat exchanger plate group each have uncovered openings on the outlet surface and the suction surface, in which case an "uncovered" opening means an opening which does not open into a fluid supply line formed on the heat exchanger block or into a corresponding fluid header , The fluid guide means of the first heat exchanger plate group thus open during operation to a fluid space surrounding the heat exchanger block. In particular, the fluid channels of the first heat exchanger plate group in a plate heat exchanger condenser evaporator may run parallel through the entire heat exchanger block, and either no fluid distribution and fluid collection structures are provided, or they are open ended (Open End Distributors).

In a plate heat exchanger condenser evaporator, on the other hand, the fluid guides of a second group of heat exchanger plates, as well as in normal plate heat exchangers, run between a fluid supply line and a fluid manifold. The fluid supply line communicates with fluid distribution structures formed in the heat exchanger plates through the fluid supplied through the fluid supply line to the entire width of the fluid distribution line Heat exchange ribs is distributed. Accordingly, the fluid manifold is in communication with fluid collection structures formed in the heat exchanger plates. Through the latter, fluid is collected over the entire width of the heat exchange fins and fed to the fluid manifold. Corresponding fluid distribution structures and fluid collection structures are known in various configurations, among others from the aforementioned ALPEMA standard.

In operation, a plate heat exchanger condenser evaporator with the suction surface in a liquid bath of a condensed and to be evaporated fluid, for example, an oxygen-rich fluid in the bottom of the low pressure column of an air separation plant, immersed. Gaseous fluid to be condensed, for example a nitrogen-rich top product of the high-pressure column, is fed into the fluid supply line. The fluid guides of the first heat exchanger plate group may be aligned vertically, but at least their openings are arranged in the outlet surface but above their openings in the suction surface, to effect the so-called thermosiphon effect:
The condensed and to be evaporated fluid enters via the openings in the suction surface in the fluid guides of the first heat exchanger plate group and there undergoes a heat exchange with the gaseous, to be condensed fluid in the fluid guides the second heat exchanger plate group or there formed (partial) condensate of this fluid , This leads to a partial evaporation in the condensed and to be evaporated fluid. The resulting two-phase mixture has a lower overall density than the condensed and to be evaporated fluid from which it was formed. It therefore rises in the fluid guides of the first heat exchanger plate group and exits via the openings in the exit surface. This results in a continuous flow in the fluid guides of the first heat exchanger plate group. The fluid vaporized in the fluid guides of the first heat exchanger plate group transitions into a gas space above the exit surface, unevaporated fluid flows back into the liquid bath on the outside of the heat exchanger block.

At the same time, due to the heat exchange in the fluid channels of the second heat exchanger plate group, as mentioned above, a (partial) condensation. In this way, a (partial) condensate of the fluid fed in via the fluid supply line, ie a liquid stream or a two-phase stream, can be withdrawn from the fluid collecting line of this second heat exchanger plate group.

In plate heat exchanger condenser evaporators, when a gas mixture is fed into the fluid supply line of the second heat exchanger plate group, segregation may occur in the fluid distribution structures of the heat exchanger plates by selective condensation and other effects, i. in certain areas, a gas component of the gas mixture can accumulate. This is particularly disadvantageous if one of the gas components is an inert gas. In such areas, the fluid passage can be prevented and / or an effective heat exchange can be hindered. In effect, this leads to a reduction in the total available heat exchange surface.

The invention has as its object to provide measures which eliminate the disadvantages mentioned, in particular to prevent segregation in a plate heat exchanger condenser evaporator in a simple and effective manner.

Disclosure of the invention

This object is achieved by a plate heat exchanger condenser evaporator and a process for the cryogenic separation of air with the features of the independent claims. Embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

The present invention proposes a plate heat exchanger condenser evaporator with a heat exchanger block having a number of heat exchanger plates with fluid routing structures. The heat exchanger block has outer surfaces. If the heat exchanger block is cuboid, there are a total of six outer surfaces. Hereinafter, a first, a second, a third and a fourth outer surface of the heat exchanger block are considered. The first outer surface is opposite to the second outer surface, the third outer surface of the fourth. The first outer surface and the second outer surface are in particular parallel to each other, as well as the third and the fourth. The distance between the first and second outer surfaces corresponds to the height of the heat exchanger block. The first outer surface is in operation of the plate heat exchanger condenser evaporator at the top of the heat exchanger block, the second at the bottom thereof. The second outer surface and a portion of the third and fourth outer surfaces are immersed in a liquid bath of condensed fluid during operation of the plate heat exchanger condenser evaporator. The heat exchanger plates comprise a plurality of first and a plurality of second heat exchanger plates, which basically have different functions and are constructed differently.

The fluid guide structures of the first heat exchanger plates and thus the first heat exchanger plates in total, are adapted to evaporate the condensed fluid partially or completely, so that this fluid rises in the fluid guiding structures of the first heat exchanger plates upwards, to which the explained thermosiphon effect is used. The fluid routing structures of the first heat exchanger plates have uncovered openings from both fluid supply lines and fluid manifolds, so that direct entry of the condensed fluid and direct exit of the partially or fully vaporized fluid can be ensured.

The said openings are hereinafter also referred to as "first" and "second" openings, wherein via the second openings, the condensed liquid is sucked and discharged via the first openings in partially or completely vaporized form. So that suction of the condensed liquid from the liquid bath is possible, the second openings used for this purpose are arranged below the liquid level of the liquid bath or the liquid level of the liquid bath is brought to a corresponding height. On the other hand, the exit of the partially or completely vaporized fluid via the first openings can take place either completely above, partly above and partly below or also completely below the liquid level of the liquid bath. Also in the two latter cases, a liquid circulation can be effected by the thermosiphon effect, if the evaporation can be made a sufficient pressure difference between the respective openings, which overcomes the hydrostatic pressure gradient.

On the other hand, the fluid guiding structures of second heat exchanger plates, which are adapted for (partial) condensation of a fluid, run between a fluid supply line arranged on the heat exchanger block and a fluid manifold arranged on the heat exchanger block, so that a fluid to be condensed is fed in via the fluid supply line and via the fluid collecting line in (FIG. partially) condensed form can be removed.

The present invention contemplates that the fluid delivery line on the first outer surface, i. in operation on top of the plate heat exchanger condenser evaporator, is arranged. The arrangement of the fluid supply line and the specific configuration of corresponding fluid distribution structures in the fluid-guiding structures of the second heat exchanger plates makes it possible for the present invention to avoid the disadvantageous effect mentioned above of partial separation of a corresponding mixed fluid. By the use of the present invention, the homogeneous distribution of corresponding injected fluid is improved and thus the heat exchange efficiency of a corresponding plate heat exchanger condenser evaporator increases overall. In the context of the present invention, it has been recognized that such a fluid distribution offers significant advantages, although the openings of the fluid-guiding structures of the first heat exchanger plates conventionally arranged on the first outer surface of the heat exchanger block (referred to herein as "first" openings) consist of one through the fluid supply line hidden area must be relocated. It was recognized that the expense of a corresponding displacement and the possible disadvantages due to the influence of the evaporation path are thereby outweighed by the improved fluid distribution in the second heat exchanger plates. Overall, there is a significantly improved heat exchange efficiency.

According to the invention, the first openings of the fluid guiding structures of the first heat exchanger plates are arranged either on the first outer surface in a region not covered by the fluid supply line or in each case in a first region of the third and the fourth outer surface. The first openings can therefore be displaced on the first outer surface from a region covered by the fluid supply line or to the third and fourth outer surface. The "first areas" of the third and fourth outer surface are respectively above the liquid level of the fluid to be evaporated by the plate heat exchanger condenser evaporator.

Advantageously, the first openings of the fluid guiding structures of the first heat exchanger plates are formed on the first outer surface by fluid collecting structures and displaced by them in the manner just mentioned from the area in which the fluid supply line is located. The fluid collection structures communicate with heat exchange fins in a central region of the fluid routing structures. This makes it possible, without affecting the (partial) evaporation of a corresponding fluid in the first heat exchanger plates or in their fluid guide structures to arrange a fluid supply line on the first outer surface.

Particular advantages arise when the fluid supply line extends in a central region of the first outer surface perpendicular to the heat exchanger plates, that is, there is a central feed of fluid into the second fluid guiding structures. This makes it possible to achieve a particularly homogeneous distribution of corresponding fluid and it is possible to completely dispense with a horizontal fluid feed or corresponding fluid distribution structures.

If the first openings of the first heat exchanger plates formed by the fluid collection structures, as provided according to the invention, are located on the first outer surface in a region not covered by the fluid supply line or in each case in a first region of the third and the fourth outer surface, they can be referred to as double exit Be formed distributors, as they are known in principle from the field of heat exchanger technology and described in the aforementioned ALPEMA standard. However, as noted, they do not end up as conventional double exit distributors in fluid distribution manifolds.

Advantageously, the fluid guide structures of the second heat exchanger plates on the first outer surface are provided with openings which open into the fluid supply lines and are formed by the Fluidverteilstrukturen, said Fluidverteilstrukturen communicate with heat exchange ribs in a central region of the fluid guide structures. By a suitable design of corresponding fluid distribution structures, a particularly homogeneous distribution of Ensures fluid to the corresponding heat exchange ribs. Advantageously, the Fluidverteilstrukturen the second heat exchanger plates are designed as central distributors, as also known in principle from the mentioned literature, resulting in the aforementioned advantages.

According to a particularly preferred embodiment of the present invention, the position of the fluid manifold is also changed from the arrangement in conventional plate exchanger condenser evaporators, i. the fluid manifold is disposed on the second outer surface of the heat exchanger block. In this case, the openings of the fluid guide structures of the first heat exchanger plates located in a conventional plate heat exchanger condenser evaporator on the second outer surface (referred to as "second" openings herein) are arranged in an area uncovered by the fluid manifold, so that suction is made possible by condensed fluid.

In the mentioned particularly preferred embodiment of the invention, the second openings of the fluid guiding structures of the first heat exchanger plates are formed on the second outer surface in an area not covered by the fluid collecting line and / or respectively in second areas of the third and fourth outer surfaces by fluid distribution structures connected to the heat exchange fins in the central region of the fluid routing structures. A partial evaporation of fluid that is sucked through corresponding openings, we thereby not affected, even if the openings of the fluid guide structures of the first heat exchanger plates are displaced accordingly.

Advantageously, in such a case, the fluid manifold is arranged in a central region of the second outer surface and perpendicular to the heat exchanger plates, so that fluid can be collected centrally and therefore no segregation effects can occur here. As explained above with regard to the fluid collection structures of the first heat exchanger plates, the fluid distribution structures of the first heat exchanger plates are advantageously designed as so-called double-entry distributors, as described in the above-described standard literature, if the openings of the fluid guiding structures of the first heat exchanger plates are arranged on the second outer surface.

In the illustrated case of arranging the fluid manifold in a central region of the second outer surface and perpendicular to the heat exchanger plates, the fluid guide structures of the second heat exchanger plates on the second outer surface form openings that open into the fluid manifolds and are formed by fluid collection structures that communicate with the heat exchange fins in the central one Area of fluid management structures in connection. As mentioned, advantageously, the fluid collection structures of the second heat exchanger plates can be designed as central distributors, which reliably prevents segregation.

The mentioned first regions of the third and fourth outer surfaces adjoin the first outer surface, the second regions of the third and fourth outer surfaces adjoin the second outer surface. The first and second areas of the third and fourth outer surfaces each comprise at most 50% of the area of the respective outer surface, in particular at most 40%, 30%, 20% or 10%. The first regions of the third and fourth outer surfaces are completely above, partially above, and partially below, or below, or completely below the level of the fluid to be evaporated in operation of the plate heat exchanger condenser evaporator, the second regions completely below. Details have already been explained.

The present invention also extends to a process for the cryogenic separation of air, as it is basically described in the technical literature mentioned above. In such a process, an oxygen-enriched bottom product and a nitrogen-enriched overhead product are produced using compressed, cooled feed air in a first distillation column. Using the oxygen-enriched bottoms product from the first distillation column, an oxygen-rich bottom product and a nitrogen-rich overhead product are produced in a second distillation column.

The method according to the present invention is characterized in that one or more plate heat exchanger condenser evaporators are used in one or more of the embodiments explained above, so that a particularly good heat exchange efficiency results in such a method. On the respective advantages of said embodiments will be at this point expressly referenced, also the inventive method for the cryogenic separation of air benefits from these advantages.

The present invention provides according to a particularly preferred embodiment of the method to use the or one of the plate heat exchanger condenser evaporator as a so-called main condenser, that is, a condenser, which connects the first distillation column and the second distillation column heat exchanging. In this case, in the fluid-guiding structures of the first heat exchanger plates, the oxygen-rich bottom product of the second distillation column is partially vaporized, and in the fluid guide structures of the second heat exchanger plates, the nitrogen-enriched overhead product of the first distillation column is partially liquefied. The plate heat exchanger condenser evaporator is immersed for this purpose in a liquid bath, which is formed from the oxygen-rich bottom product of the second distillation column. Due to the thermosiphon effect, this bottom product rises in the fluid-guiding structures of the first heat exchanger plates and is partially vaporized in this case. At the same time, the nitrogen-enriched overhead product of the first distillation column is partially liquefied here.

A further preferred embodiment of the method according to the invention comprises using a corresponding plate heat exchanger condenser evaporator as the top condenser of an argon column, ie it comprises taking out a fluid from the second distillation column and feeding it into a third distillation column. The third distillation column in this case has a top condenser, in which by means of or one of the plate heat exchanger condenser evaporator (s) a portion of the oxygen-enriched bottom product of the first distillation column is partially vaporized in the fluid routing structures of the first heat exchanger plates, and in which an argon-enriched overhead of the third distillation column in the Fluid management structures of the second heat exchanger plates is partially liquefied. The invention is suitable for use in so-called crude argon columns, in which an argon-enriched product is obtained, but also in so-called argon discharge columns, which are only intended to reduce an argon content in the first and / or second distillation column, so that in this an oxygen product gain in greater purity.

Here, an argon discharge column refers to an argon-oxygen separation column, which serves not for the recovery of a pure argon product but for the discharge of argon from the air to be separated in the first and second distillation columns. Their circuit differs only slightly from that of a classical crude argon column, but it contains significantly less theoretical plates, namely less than 40, especially between 15 and 30. Like a crude argon column, the bottom portion of an argon discharge column is connected to an intermediate point of the second distillation column and the argon discharge column becomes cooled by a top condenser, on the evaporation side relaxed bottom liquid is introduced from the high pressure column. An argon discharge column has no bottom evaporator. The top condenser may, as mentioned, be designed as a plate heat exchanger condenser evaporator.

The invention will be explained in more detail below with reference to the accompanying drawings, in which preferred embodiments of the invention compared to the prior art are illustrated.

Brief description of the drawings

• FIG. 1 shows a non-inventive plate heat exchanger condenser evaporator in a schematic representation.
• FIG. 2 shows a ("second") heat exchanger plate of the plate heat exchanger condenser evaporator according to FIG. 1 ,
• FIG. 3 shows a plate heat exchanger condenser evaporator according to an embodiment of the invention in a schematic representation.
• FIG. 4 shows a ("second") heat exchanger plate of the plate heat exchanger condenser evaporator according to FIG. 3 ,
• FIG. 5 shows a ("second") heat exchanger plate of a plate heat exchanger condenser evaporator according to another embodiment of the invention in a schematic representation.
• FIG. 6 shows a ("first") heat exchanger plate of the plate heat exchanger condenser evaporator according to FIG. 3 ,
• FIG. 7 shows a ("first") heat exchanger plate of a plate heat exchanger condenser evaporator according to another embodiment of the invention in a schematic representation.
• FIG. 8 shows a ("first") heat exchanger plate of a plate heat exchanger condenser evaporator according to another embodiment of the invention in a schematic representation.

In the figures, corresponding elements are given identical reference numerals and will not be explained repeatedly for the sake of clarity.

Detailed description of the drawings

FIG. 1 shows a non-inventive plate heat exchanger condenser evaporator in a schematic and partially opened representation. The plate heat exchanger condenser evaporator FIG. 1 is designated overall by 110.

A heat exchanger block 10 of the plate heat exchanger condenser evaporator is formed of alternately arranged heat exchanger plates 20 and 30, wherein the heat exchanger plates 20 hereinafter referred to as "first" heat exchanger plates and the heat exchanger plates 30 hereinafter referred to as "second" heat exchanger plates. Corresponding heat exchanger plates are partially explained in more detail in the following figures. Only two corresponding heat exchanger plates 20, 30 are provided with reference numerals, but the entire heat exchanger block 10 is constructed in total from corresponding heat exchanger plates 20, 30.

Both in the first heat exchanger plates 20 and in the second heat exchanger plates 30 each fluid guide structures are formed, which are designated for the first heat exchanger plates 20 with 21 and for the second heat exchanger plates 30 with 31. As mentioned, under "fluid routing structures", here language used understood both the typically arranged in a central region of the corresponding heat exchanger plates 20, 30 heat exchange ribs, as well as the terminal Fluidverteil- or fluid collection structures (distributors). In the presentation of the FIG. 1 are the heat exchange ribs, which, as mentioned, can also be provided in another embodiment, illustrated for both heat exchanger plates 20, 30 and here in each case with 215 and 315 respectively. Corresponding heat exchange fins are, as explained, referred to in the relevant literature as Heat Exchange Fins.

In the FIG. 1 However, only one of the second heat exchanger plates 30 Fluidverteilstrukturen 313 illustrated. The fluid distribution structures 313 have the task, a fluid which is provided via a fluid supply line 40, which is also commonly referred to as header and enters through openings 311 in corresponding second heat exchanger plates 30, over the entire width of the second heat exchanger plates 30 to the heat exchange ribs 315 distribute and thus ensure an effective heat exchange. As mentioned and also with reference to the following FIG. 2 However, this can lead to unequal distributions and corresponding disadvantageous effects. Not illustrated in FIG. 1 Fluid collecting structures of the second heat exchanger plates 30, the fluid that exits the heat exchanger fins 315, collect and supply a fluid manifold 50.

The first heat exchanger plates 20 have, in contrast to the second heat exchanger plates 30, no or possibly open-end Fluidverteilstrukturen on, but in the FIG. 1 not illustrated. The fluid guide structures 21 of the heat exchanger plates 20 formed from the heat exchange ribs 215 and optionally the open-end Fluidverteilstrukturen therefore extend between a first outer surface of the heat exchanger block 10, here denoted by 11, and a second outer surface of the heat exchanger block 10, which is designated here by 12. They have both fluid supply lines and fluid manifolds uncovered openings to these outer surfaces 11, 12, wherein in the illustration of FIG. 1 only the openings to the first outer surface 11 ("first" openings) are illustrated and labeled 211. To avoid misunderstandings, it should be emphasized that the first outer surface 11 in the representation of FIG. 1 in operation on top of the heat exchanger block 10 and the second outer surface 12 is located on the underside thereof. The edges of the heat exchanger plates 20, 30 further form a third and a fourth outer surface of the heat exchanger block 10, here denoted by 13 and 14. (The fourth outer surface 14 is in FIG. 1 covered.)

By arranging the fluid supply line 40 and the fluid manifold 50, however, the fluid guide structures 31 of the second heat exchanger plates 30 run between the fluid supply line 40 and the fluid manifold 50. Via the fluid supply line 40, a gaseous fluid to be condensed, for example a nitrogen-rich top product of a high-pressure column of an air separation plant, is fed , And the heat exchanger block 10 is immersed to a certain height in a liquid bath of a fluid to be vaporized, for example, in an oxygen-rich liquid in the bottom of a low pressure column of an air separation plant, it comes to the above-mentioned Termosiphoneffekt.

In FIG. 2 is one of the second heat exchanger plates 30 of the in FIG. 1 illustrated plate heat exchanger condenser evaporator illustrated in plan view. In addition, the fluid supply line 40 and the fluid manifold 50 are shown schematically, but they are not part of the second heat exchanger plates 30 themselves but are applied to a heat exchanger block 10 formed using the second heat exchanger plates 30. To illustrate, the outer surfaces 11 to 14 of a heat exchanger block 10 are further indicated, which are defined by a corresponding heat exchanger plate 30.

As mentioned, during operation, fluid is supplied via the fluid supply line 40 and enters the fluid guide means 31 of the second heat exchanger plates 30 via the openings 311. The fluid is first distributed by means of Fluidverteilstrukturen 313 on the entire width of the heat exchanger plate 30. In the illustrated example, the fluid distribution structures 313 and collection structures 314 discussed below are each illustrated as Type B diagonal manifolds, however, other forms of fluid distribution and fluid collection structures may be used, such as those discussed in the aforementioned ALPEMA Standard illustrated forms. By means of the fluid distribution structures 313 over the entire width of the heat exchanger plate 30th Distributed fluid ideally enters the area of the heat exchange fins 315 at the same flow rate and composition over the entire width and is ideally collected over the entire area of the heat exchange fins 315 by means of the fluid collection structures 314. The fluid collected by the fluid collection structures 314 exits the second heat exchanger plate 30 via the openings 312 and is thus supplied to a fluid manifold 50.

As mentioned, it may be in second heat exchanger plates 30, as in FIG. 2 However, for example in the area of the fluid distribution structures 313, but also in the area of the fluid collection structures 314, demixing effects occur, in particular when a gas mixture containing inert gases is fed via the fluid supply line 40. As a result, in certain areas, based on the entire width of the second heat exchanger plate 30, pure or inert gases or segregated gas components accumulate and impede the passage of fluid through the heat exchange fins 315 or other areas of the Fluidleiteinrichtungen 31. The effective heat exchange capacity of a corresponding second heat exchanger plate 30 and thus an entire heat exchanger block 10 or plate heat exchanger condenser evaporator 110, is thus significantly reduced.

In FIG. 3 a plate heat exchanger condenser evaporator according to an embodiment of the invention is illustrated schematically and designated 100 as a whole. Already in the description of FIG. 1 mentioned elements will not be explained again.

In contrast to the plate heat exchanger condenser evaporator 110 of FIG. 1 Here, however, the fluid supply line 40 on the first outer surface 11, that is, the top of the heat exchanger block 10 is disposed. This leads, as also explained below, to a significantly better fluid distribution in the second heat exchanger plates 30 and their fluid guiding structures, because they can be made particularly favorable. At the same time, the openings 311 of the fluid distribution structures 313 of these second heat exchanger plates 30 differ from those in FIG FIG. 1 illustrated type trained.

For example, the fluid collection structures of the heat exchanger plates 30 may continue as in FIG FIG. 2 illustrated or obtained a different configuration, depending on where the fluid manifold 50 is arranged. If this is further arranged laterally of the heat exchanger block 10, as in the plate heat exchanger condenser evaporator 110 according to FIG. 1 , an arrangement is used, as in the FIG. 4 is shown. However, it is also possible to displace the fluid collecting line 50 to the second outer surface 12 of the heat exchanger block 10, in which case an arrangement according to FIG. 5 is used. This also leads to consequences for the design of the first heat exchanger plates 20, as with reference to the FIGS. 6 to 8 explained.

According to FIG. 3 For example, the first openings 211 of the fluid guide structures 21 of the first heat exchanger plates 20 are displaced by suitable fluid collection structures from a portion of the first outer surface 11 obscured by the fluid supply line 40, but still disposed on the first outer surface 11. However, the openings 211 of the fluid guiding structures 21 of the first heat exchanger plates 20 may also be displaced on the outer surfaces 13 and 14, as with respect to FIG. 8 shown.

In FIG. 4 is, as mentioned, a second heat exchanger plate 30 of a plate heat exchanger condenser evaporator according to FIG. 3 illustrated. Again, the fluid supply line 40 and the fluid manifold 50 are shown.

Unlike the in FIG. 2 As already mentioned, however, the heat exchanger plate 30 shown here has the openings 311 of the fluid distribution structures 313 arranged on top of the heat exchanger plates 30 and thus the first outer surface 11 of the heat exchanger block 10. The same applies to the fluid supply line 40 additionally illustrated here. Due to the symmetrical design of the fluid distribution structures 313, the fluid can spread better over the entire width of the heat exchanger plate 30 or the heat exchange ribs 315, so that it no longer exists in the area of the fluid distribution structures 313 can lead to demixing effects. As mentioned, are in the in FIG. 4 However, as shown in a plate heat exchanger condenser evaporator 110 according to FIG. 2, the embodiment of a second heat exchanger plate 30 illustrated in FIG. 2 illustrates the fluid collection structures as in conventional second heat exchanger plates 30 FIG. 1 used, trained.

However, as mentioned, it is also possible to provide the fluid manifold 50 on a second outer surface 12 and the underside of the heat exchanger block 10, respectively. A used for this case second heat exchanger plate 30 is in FIG. 5 illustrated. In this case, the fluid collecting structures unite the fluid which emerges from the heat exchange ribs 315 in a central region, so that no or less separation effects can also occur here.

As explained several times, the second heat exchanger plates 30 are arranged according to the preceding figures for partially or completely condensing a fluid, the first heat exchanger plates 20, however, are adapted to evaporate a fluid partially or completely. The first heat exchanger plates 20 are operated on the basis of the aforementioned termosiphon effect.

Hereinafter, first heat exchanger plates 20 are illustrated, as they can be used in the previously described embodiments, namely, when a fluid supply line on the top and a fluid manifold is arranged either laterally or on an underside of the heat exchanger block 11. In both cases, the fluid supply line 40 and the fluid manifold 50 are illustrated, but the fluid guide structures 21 are not in communication with such fluid supply lines 40, 50.

The first heat exchanger plates 20 are, as mentioned, adapted to partially or completely evaporate a fluid and thus bring about the Termosiphon effect. For this purpose, the fluid guide structures 21 must have openings which are uncovered by both fluid supply lines and fluid collecting lines. If the fluid supply line 40 is arranged on the first outer surface of the heat exchanger block 10, no openings of fluid guiding structures 21 of the heat exchanger plates 20 (like those in FIG FIG. 1 illustrated first openings 211) may be provided. These first openings are therefore in the in FIG. 6 example connected to fluid collection 213. The fluid collection structures 213 are designed in the manner of so-called double-exit distributors and provided with openings 211 on the first outer surface 11 of the heat exchanger block 10. However, other configurations may be provided. About the first openings 211 is a partially vaporized fluid discharged at an upper side of the heat exchanger block 10 and the first outer surface 11. Unevaporated fluid runs off on the outside of the heat exchanger block 10. On the underside or the second outer surface 12 of the heat exchanger block 10, on the other hand, openings 212 of the fluid-guiding structures 21 ("second" openings) are provided, which are connected without or only to so-called open-end fluid distribution devices 214. Fluid can thus freely enter the heat exchange ribs 215 and ascend in this way.

However, if an arrangement is chosen in which the fluid manifold 50 is disposed on a bottom surface or second outer surface 12 of the heat exchanger block 10, then the second openings of the fluid routing structures 21 must also be displaced to an area that is not obscured by the fluid manifold. For this purpose, a Fluidverteilstruktur 214 is used, which is formed for example in the manner of a so-called double-entry distributor. This is in FIG. 7 shown. Alternatively, it may also be provided, as already mentioned several times, to displace the first and / or the second openings 211 and / or 212 onto the third and fourth outer surfaces 13, 14 of the heat exchanger block 10. This is in FIG. 8 illustrates in the case that the fluid distribution line 40 on the first outer surface 11 and the fluid collecting line 50 on the second outer surface 12 is arranged. On the other hand, if the fluid manifold 50 is not disposed on the second outer surface 12, the formation of the second openings 212 may be as in FIG FIG. 6 shown done. Also a combination of in FIG. 7 and 8th shown embodiments is possible, ie the formation of the first openings 211 may as in FIG. 6 shown and the formation of the second openings 212 as in FIG. 8 shown or vice versa.

Claims (15)

1. Plate heat exchanger condenser-evaporator (100) having a heat-exchanger block (10) which comprises a number of heat-exchanger plates (20, 30) having fluid-conducting structures (21, 31), wherein the heat-exchanger block (10) comprises a first outer surface (11), a second outer surface (12) opposite the first outer surface (11), a third outer surface (13) and a fourth outer surface (14) opposite the third outer surface (13), wherein the fluid-conducting structures (21) of first heat-exchanger plates (20) comprise first and second openings (211, 212) on the heat-exchanger block (10), which openings are not covered by fluid feed lines or by fluid-collecting lines, and wherein the fluid-conducting structures (31) of second heat-exchanger plates (30) run between a fluid feed line (40) arranged on the heat-exchanger block (10) and a fluid-collecting line (50) arranged on the heat-exchanger block (10), characterized in that the fluid feed line (40) is arranged on the first outer surface (11) and in that the first openings (211) of the fluid-conducting structures (21) of the first heat-exchanger plates (20) are arranged either in a region of the first outer surface (11) that is not covered by the fluid feed line (40) or in a first region of the third outer surface (13) and a first region of the fourth outer surface (14).
2. Plate heat exchanger condenser-evaporator (100) according to Claim 1, in which the first openings (211) of the fluid-conducting structures (21) of the first heat-exchanger plates (20) are formed by fluid-collecting structures (213) that are connected to heat-transfer fins (215) in a central region of the fluid-conducting structures (21).
3. Plate heat exchanger condenser-evaporator (100) according to Claim 2, in which the fluid feed line (40) runs in a central region of the first outer surface (11) at right angles to the heat-exchanger plates (20, 30).
4. Plate heat exchanger condenser-evaporator (100) according to Claim 2 or 3, in which the fluid-collecting structures (213) of the first heat-exchanger plates (20) are constructed as double-exit distributors.
5. Plate heat exchanger condenser-evaporator (100) according to any one of the preceding claims, in which the fluid-conducting structures (31) of the second heat-exchanger plates (30) comprise openings (311) on the first outer surface (11), which openings open out into the fluid feed line (40) and are formed by fluid-distribution structures (313) that are connected to heat-transfer fins (315) in a central region of the fluid-conducting structures (31).
6. Plate heat exchanger condenser-evaporator (100) according to Claim 5, in which the fluid-distribution structures (313) of the second heat-exchanger plates (30) are constructed as central distributors.
7. Plate heat exchanger condenser-evaporator (100) according to any one of the preceding claims, in which the fluid collecting line (50) is arranged on the second outer surface (12).
8. Plate heat exchanger condenser-evaporator (100) according to Claim 7, in which the second openings (212) of the fluid-conducting structures (21) of the first heat-exchanger plates (20) are formed by fluid-distribution structures (214) that are connected to the heat-transfer fins (215) in the central region of the fluid-conducting structures (21), wherein the second openings (212) formed by the fluid-distribution structures (214) are either arranged in a region of the second outer surface (12) that is not covered by the fluid-collecting line (50), or are respectively arranged in a second region of the third outer surface (13) and a second region of the fourth outer surface (14).
9. Plate heat exchanger condenser-evaporator (100) according to Claim 8, in which the fluid-collecting line (50) runs in a central region of the second outer surface (12) at right angles to the heat-exchanger plates (20, 30).
10. Plate heat exchanger condenser-evaporator (100) according to Claim 8 or 9, in which the fluid-distribution structures (214) of the first heat-exchanger plates (20) are constructed as double-entry distributors.
11. Plate heat exchanger condenser-evaporator (100) according to any one of Claims 8 to 10, in which the fluid-conducting structures (31) of the second heat-exchanger plates (30) on the second outer surface (12) comprise openings (312) that open out into the fluid-collecting line (50) and are formed by fluid-collecting structures (314) that are connected to the heat-transfer fins (315) in the central region of the fluid-conducting structures (31).
12. Plate heat exchanger condenser-evaporator (100) according to Claim 11, in which the fluid-collecting structures (314) of the second heat-exchanger plates (30) are constructed as central distributors.
13. Process for low-temperature air separation, in which an oxygen-enriched sump product and a nitrogen-enriched overhead product are generated using compressed, cooled feed air in a first distillation column, and an oxygen-rich sump product and a nitrogen-rich overhead product are generated in a second distillation column, using the oxygen-enriched sump product from the first distillation column, characterized in that one or more plate heat exchanger condenser-evaporators (100) according to any one of the preceding claims are used.
14. Process according to Claim 13, in which by means of the, or one of the, plate heat exchanger condenser-evaporators (100), the oxygen-rich sump product of the second distillation column is partially evaporated in the fluid-conducting structures of the first heat-exchanger plates, and in which the nitrogen-enriched overhead product of the first distillation column is partially liquefied in the fluid-conducting structures of the second heat-exchanger plates.
15. Process according to Claim 13, in which a fluid is withdrawn from the second distillation column and fed into a third distillation column, wherein the third distillation column comprises an overhead condenser in which, by means of the, or one of the, plate heat exchanger condenser-evaporators (100), a part of the oxygen-enriched sump product of the first distillation column is partially evaporated in the liquid-conducting structures of the first heat-exchanger plates, and in which an argon-enriched overhead product of the third distillation column is partially liquefied in the fluid-conducting structures of the second heat-exchanger plates.

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