EP2026024A1 - Process and device for producing argon by cryogenic separation of air - Google Patents

Abstract

The method involves compressing feed air (1) and passing in a distillation column system for nitrogen-oxygen separation. An argon containing flow (72) removes the distillation column system for nitrogen-oxygen separation. A crude argon column (25) is fed to the argon containing flow. A head condenser (24) is formed as return condenser, and a top gas of the crude argon column is passed in the return passage of the return condenser. An independent claim is included for a device for extracting argon by low-temperature separation of air.

Description

The invention relates to a method according to the preamble of patent claim 1.

Methods and devices for the cryogenic decomposition of air are known, for example, from Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, Chapter 4 (pages 281 to 337). The distillation column system for nitrogen-oxygen separation of the invention may be formed as a single column system for nitrogen-oxygen separation, as a two-column system (for example as a classic Linde double column system), or as a three or more column system. In addition to the columns for nitrogen-oxygen separation and for the production of argon, further steps for obtaining other air components may be provided in the method, in particular further noble gases.

The "crude argon column" within the meaning of the claim is used for argon-oxygen separation. The crude argon column may be formed by a one-piece column or by a two- or multi-part column, as in EP 628777 B1 is described. The "pure argon column" is used for argon-nitrogen separation. The "crude argon stream" has a higher argon concentration than the "argon-containing stream". The "pure argon product stream" has a higher argon concentration than crude argon stream and is preferably withdrawn from the bottom of the pure argon column, for example from its bottom.

The only source of reflux liquid of the crude argon column is a top condenser. This top condenser can be formed from one, two or more plate heat exchanger blocks, which are connected in parallel on the evaporation side and on the liquefaction side. Cooling fluid flows into the evaporation passages at one end and out of the evaporation passages at the other end. A counterflow within the evaporation passages does not take place. Rather, liquid remaining cooling fluid and vaporized cooling fluid are conducted in the DC flow within the evaporation passages. Is the top condenser as Bath evaporator formed, the cooling fluid flows in the evaporation passages from bottom to top.

Processes for argon recovery of the type mentioned are, for example DE 2325422 A . EP 171711 A2 . EP 377117 B2 (= US 5019145 ) DE 4030749 A1 . EP 628777 B1 (= US 5426946 ) EP 669508 A1 (= US 5592833 ) EP 669509 B1 (= US 5590544 ) EP 942246 A2 . EP 1103772 A1 . DE 19609490 (= US 5669237 ), Figure 8, EP 1243882 A1 (= US 2002178747 A1 ) and EP 1243881 A1 (= US 2002189281 A1 ) is known, both conventional condenser used as the top condenser of the crude argon column, are conducted in gas to be condensed and condensed liquid in the liquefaction passages in cocurrent.

The invention has for its object to provide a method of the type mentioned above and a corresponding device, which are economically particularly favorable to operate by having an increased product yield, higher product purity, lower operating costs and / or lower investment costs.

This object is achieved in that the top condenser of the crude argon column is designed as a reflux condenser and top gas of the crude argon column is introduced into the return passages of the reflux condenser.

Under "reflux condenser" (also called dephlegmator) is here understood a heat exchanger having return passages. These return passages are pressurized from below with steam (here: overhead gas of the crude argon column). This condenses at least partially when ascending in the return passages. The return passages are designed so that the condensed liquid is not entrained, but flows down. Due to the countercurrent of vapor and liquid, a rectification takes place in the return passages. The condensate, which exits at the lower end, is enriched in less volatile components, the steam exiting overhead is more volatile.

There are various types of flyback capacitors known. The heat exchanger block (or even a plurality of heat exchanger blocks) may be arranged inside a pressure vessel, as described, for example, in US Pat EP 1189000 A2 is shown, or the heat exchanger block is completed on all sides by headers, see for example US 6128920 , Alternatively, the reflux condenser in the head of a separation column (here: the crude argon column) may be installed, the return passages are at its lower end in communication with the upper region of the separation column, see German patent application 102006037058 and corresponding applications. The one or more heat exchanger blocks of the reflux condenser are preferably designed as a plate heat exchanger, in particular as a brazed aluminum plate heat exchanger.

Spatial terms such as "top", "bottom", "side", etc. always refer to the orientation of the reflux condenser in normal operation.

A reflux condenser not only allows heat exchange, but also mass transfer between the gas rising in the return passages and the liquid flowing down there, similar to the corrugated packings of a mass transfer column. This release effect can be expressed as the HETP value (Height Equivalent to One Theoretical Plate). The HETP value of the capacitor is in the range of 300 to 600 mm. Thus, for example, a 1.5 m high reflux condenser acts like up to five theoretical plates. However, this effect does not affect the argon-oxygen separation at the top of the crude argon column, ie the use of the reflux condenser does not save mass transfer elements (practical trays, ordered packing or disordered packing) in the crude argon column.

Therefore, a reflux condenser in argon recovery has hitherto been used only as a top condenser when no crude argon but pure argon is recovered in the column, which is connected directly to the distillation column system for nitrogen-oxygen separation (see US 5133790 ). In this case, both the argon-oxygen separation and the argon-nitrogen separation are made in a single argon column and a separate pure argon column for argon-nitrogen separation is expressly not provided. The upper area of the argon column is off US 5133790 is not used for argon-oxygen separation (as in the crude argon column of the invention), but for argon nitrogen separation, which in the Method of the type mentioned is carried out practically exclusively in the pure argon column.

So far, therefore, no reason has been seen to lay in processes that have their own pure argon column for argon nitrogen separation, a portion of the argon-nitrogen separation in the crude argon column or their overhead condenser, as this is no floors in the columns are saved.

In the context of the invention, however, it has been found that the use of such a reflux condenser at the top of the crude argon column has a further advantage. Such capacitors are regularly designed as a condenser-evaporator. Against the condensing on the liquefaction side (return passages) head gas thus a cooling fluid is evaporated on the evaporation side. The heat exchanger block is usually arranged in a bath. Because of the hydrostatic pressure, the temperature in the evaporation passages rises from top to bottom.

Due to the separating effect of the reflux condenser at the top of the crude argon column, the gas flowing upwards in the return passages becomes increasingly nitrogen-rich and is the coldest at the top of the condenser because of the increased nitrogen content (see FIG. 4 ). Thus, the temperature profile in the return passages adapts to those of the evaporation passages. In this way, the return condenser creates a natural tendency for a driving temperature gradient which remains almost constant over the entire block height. In the conventional crude argon capacitor, however, the driving temperature gradient in the lower capacitor area is always much smaller than in the upper area. This weakens the contribution of the heating surface located in the lower part of the condenser to the total heat exchange. In the method according to the invention, however, the temperature difference between evaporation and liquefaction passages is almost constant. Thus, the exchange losses can be reduced, or the exchange area is reduced accordingly, thus reducing the investment costs.

This increases product purity and / or product yield. If the separation efficiency remains constant or less pronounced, the number of theoretical plates in the crude argon column be reduced; This reduces the investment costs of the system.

It is particularly advantageous if, in the invention, the liquid cooling fluid is supplied to the evaporation passages at its lower end and the mixture of vaporized cooling fluid and liquid remaining cooling fluid is withdrawn from the lower end of the evaporation passages. For example, the top condenser may be formed as a bath evaporator, in which the evaporation passages are open at the top and bottom and the cooling fluid is guided by the thermosiphon effect from bottom to top through the evaporation passages.

In one embodiment of the invention, the top condenser is formed by exactly one plate heat exchanger block.

It is particularly favorable if, in the method according to the invention, the crude argon stream is withdrawn from the upper region of the return passages. The gas fraction remaining after flowing through has a particularly high argon concentration and its oxygen content is particularly low. Although the crude argon stream thus also contains a relatively large amount of nitrogen; However, this can be separated easily in the pure argon column.

In a further embodiment of the invention, no residual gas stream is withdrawn from the upper region of the crude argon column and from the reflux passages. Preferably, no further stream is withdrawn from the upper region, including the return passages, in addition to the crude argon stream. For example, in addition to the crude argon stream, the crude argon column is drained of just another stream which is returned to the nitrogen-oxygen separation distillation column system (for example, the low-pressure column of a two-column system from which the argon-containing stream is withdrawn).

It is also advantageous if the crude argon stream of the crude argon column or the top condenser is taken off in gaseous form and at least partially, for example completely condensed, upstream of its introduction into the pure argon column in an additional condenser. As a result, the crude argon stream can be introduced at least partially, for example completely in liquid form, into the pure argon column.

This additional capacitor and the following measures can also be used in processes in which the top condenser is not designed as a reflux condenser.

Preferably, the top condenser and the additional condenser are designed as a condenser-evaporator, wherein both evaporation passages are fed with the same cooling fluid. The cooling fluid is partially vaporized in the evaporation passages, whereby liquid is entrained by the thermosiphon effect and returned to the liquid bath. As the cooling fluid, for example, oxygen-enriched liquid from the distillation column system is used for nitrogen-oxygen separation, such as from the bottom of the high-pressure column of a two-column system.

It is also advantageous if the top condenser and the additional condenser are designed as liquid bath evaporators and are arranged in the same liquid bath. Since the additional capacitor regularly has a lower height than the top condenser, the additional condenser can still be operated with a temperature at the lower end, which is lower than the temperature at the lower end of the top condenser.

If the Rohargonstrom is given up in the liquid state to the head of the pure argon column, this can be used as reflux liquid and can be dispensed with a top condenser of the pure argon column. This is in itself US 5970743 and US Pat. No. 6574988 B1 known. In combination with the reflux condenser, however, results in an increased argon yield.

It is also advantageous if a residual gas stream is withdrawn from the head of the pure argon column or from the upper region of the return passages and mixed with the feed air, in particular before its compression. This recycling of the residual gas from the head of the pure argon column or the crude argon column can also be used with advantage in argon recovery processes without reflux condenser at the top of the crude argon column. In contrast to discarding the residual gas, the argon contained in it is returned to the process. The argon yield increases accordingly. In principle, a separate recompressor can be used, but cheaper is the feed to the unpressurized Inlet air upstream of the air compressor, in particular more favorable than the direct return of the residual gas in the distillation column system for nitrogen-oxygen separation, as in US 5133790 is proposed.

The invention also relates to a device according to claims 12 to 15.

Figur 1

ein erstes Ausführungsbeispiel des erfindungsgemäßen Verfahrens ohne Zusatzkondensator,

Figur 2

ein zweites Ausführungsbeispiel mit Zusatzkondensator,

Figur 3

die Rohargonsäule und die Reinargonsäule eines dritten Ausführungsbeispiels,

Figur 4

der Temperatur- und Konzentrationsverlauf in einem Rohargonsäulen-Kopfkondensator, der gemäß der Erfindung als Rücklaufkondensator ausgebildet ist,

Figur 5

einen schematischen Längsschnitt durch eine Rücklaufpassage einer speziellen Bauform eines Rücklaufkondensators und

Figur 6

eine weitere spezielle Bauform des Rücklaufkondensators mit Längsschnitt durch eine Rücklaufpassage .

The invention and further details of the invention are explained below with reference to embodiments schematically illustrated in the drawings. Hereby show:

FIG. 1

A first embodiment of the method according to the invention without additional capacitor,

FIG. 2

a second embodiment with additional capacitor,

FIG. 3

the crude argon column and the pure argon column of a third embodiment,

FIG. 4

the temperature and concentration profile in a crude argon column overhead condenser, which is designed according to the invention as a reflux condenser,

FIG. 5

a schematic longitudinal section through a return passage of a special design of a reflux condenser and

FIG. 6

Another special design of the reflux condenser with a longitudinal section through a return passage.

Corresponding components or method steps carry the same reference numerals in the drawings.

In the process of FIG. 1 is atmospheric air 1 is sucked in via a filter 2 from an air compressor 3 and there compressed to an absolute pressure of 5.0 to 7.0 bar, preferably about 5.5 bar and is then in a direct contact cooler 4 in direct heat exchange with cooling water 5, 6 cooled, which originates (1) from an evaporative cooler 7, on the other hand (6) is supplied from an external source. The compressed and cooled air 8 is cleaned in a cleaning device 9 having a pair of containers filled with adsorbent material, preferably molecular sieve. The purified air 10 is cooled in a main heat exchanger system 11 a, 11 b, 11 c to about dew point. The cold air 12 is introduced into the high-pressure column 13 of a distillation column system for nitrogen-oxygen separation, which also has a low-pressure column 14. High-pressure column 13 and low-pressure column 14 are designed as classic Linde double column and are connected via a main condenser 15 in heat exchanging connection. The operating pressures - at the top - are 4.5 to 6.5 bar, preferably about 5.0 bar in the high pressure column and 1.2 to 1.7 bar, preferably about 1.3 bar in the low pressure column.

Liquid raw oxygen 16 is withdrawn from the sump of the high-pressure column 13, supercooled in a supercooling countercurrent 17 and further cooled to a part 19 in a sump evaporator 21 of the pure argon column 20. Another part 22 can be passed past the bottom evaporator 21. Subsequently, a part 23 flows into the evaporation space of a top condenser 24 of a crude argon column 25, another part in the evaporation space of a top condenser 27 of the pure argon column 20. The in the top condensers 24, 27 evaporated crude oxygen 28, 29 via line 30 of the low pressure column 14 at a first Supplied intermediate point. The remaining liquid portion 31 from the top condenser 24 of the crude argon column 25 is also guided to the first intermediate point of the low-pressure column 14. The remaining liquid portion 32 from the top condenser 27 of the pure argon column 20 is fed to a second intermediate point of the low-pressure column 14, which is above the first intermediate point.

Gaseous nitrogen 33 from the head of the high pressure column 13 is directed to a first portion 34 to the cold end of the main heat exchanger 11a where it is warmed to about ambient temperature and then divided into a pressurized product stream 36 (GAN I) and a recycle stream 37. The circulation stream 37 is compressed in a cycle compressor 38 with aftercooler 39 to a pressure of 25 to 60 bar, preferably about 35 bar, and cooled in the main heat exchanger 11a. A portion 40 of the high-pressure nitrogen is removed from the main heat exchanger at an intermediate temperature and expanded in an expansion turbine 41 to approximately high-pressure column pressure. The relaxed circulation stream 42 is again admixed with the cold product stream 34. Any existing liquid is previously separated (43) and fed via line 44 to the top of the low pressure column 14. Another part 61 of the high pressure nitrogen is led to the cold end of the main heat exchanger 11a and then abandoned on the high-pressure column 13.

The remaining gaseous top nitrogen 45 of the high-pressure column 13 is at least partially condensed in the main condenser 15. The generated during this process liquid nitrogen 46 is given to a part 47 of the high-pressure column 13 as reflux. Another part 48, 49 is passed to the head of the low-pressure column 14 after subcooling in the subcooling countercurrent 17. There, a part 50 can be deducted as liquid nitrogen product (LIN).

Immediately above the bottom of the low pressure column 14 gaseous oxygen 51 is removed, warmed in the main heat exchanger 11a and withdrawn via line 52 as a non-pressurized gaseous product (GOX III). A liquid oxygen stream 53 from the bottom of the low pressure column 14 is supercooled in the subcooling countercurrent 17 and fed via line 54 to a liquid tank (LOX). At least a portion of the liquid oxygen is withdrawn via line 55 to the tank again, brought in a pump 56 to the required product pressure, for example 6 to 60 bar, preferably about 31 bar, and vaporized in the main heat exchanger 11a against high pressure nitrogen (or pseudo at supercritical pressure -Vaporated) and warmed to ambient temperature and finally withdrawn via line 57 as a gaseous high pressure product (GOX I). A portion 58 of the high-pressure liquid is expanded via a throttle valve 59 to an intermediate pressure of, for example, 6 to 25 bar, preferably about 15 bar and evaporated under this lower pressure and withdrawn via line 60 as gaseous medium pressure product (GOX II).

Gaseous nitrogen 62, 63, 64 from the head of the low pressure column 14 and gaseous impurity 65, 66, 67 from an intermediate point of the low pressure column 14 are respectively supercooled in the subcooling countercurrent 17, warmed in the main heat exchanger blocks 11 c and 11 b and via line 68 - If necessary, after heating 69 - used as a regeneration gas for the cleaning device 9, fed via line 70 to the evaporative cooler 70 and / or blown off via line 71 directly into the atmosphere.

At a third intermediate point, which is arranged below the first intermediate point, an argon-containing stream 72 is taken from the low-pressure column 14 and fed to the crude argon column 25 directly above the sump. The crude argon column 25 is made in one piece in this example. Bottom liquid 73 of the crude argon column is returned via pump 74 and line 75 into the low-pressure column.

The top condenser 24 of the crude argon column 25 is designed according to the invention as a reflux condenser. Gas from the top of the crude argon column 25 flows down into the return passages where it is partially condensed. The condensate generated in this case flows in countercurrent to the rising gas in the return passages down and is used in the crude argon column 25 as a liquid reflux. On the evaporation side, the top condenser 24 is designed as a bath condenser. The cooling fluid, which is formed here by liquid crude oxygen 23, flows in at the bottom via one or more lateral openings into the evaporation passages and is partially evaporated there. Liquid is entrained by the thermosiphon effect, exits along with the vaporized portion at the top of the evaporation passages, and is returned to the liquid bath. The top condenser is thus formed on the evaporation side as a bath evaporator.

From the upper end of the return passages, a crude argon stream 76 is taken off in gaseous form via a lateral header and fed to the pure argon column 20 at an intermediate point. The top condenser of the pure argon column 20 is conventionally designed in the example on the liquefaction side, that is, the head gas 77 of the pure argon column 20 flows from top to bottom through the liquefaction passages. (Alternatively, the top condenser 27 of the pure argon column 20 and / or the main condenser 15 could be designed as reflux condenser.) From the top condenser 27, a residual gas stream 78 is withdrawn and blown off into the atmosphere in the example. Alternatively it can be returned to the distillation column system for nitrogen-oxygen separation or to the air compressor 3 via its own blower.

The bottom liquid 79 of the pure argon column 20 is vaporized to a part 80 in the bottom evaporator 21 and the generated thereby vapor 81 is as Ascending gas used in the pure argon column 20. The remainder is taken as a liquid pure argon product stream 82.

The embodiment of FIG. 2 gives way before all in the execution of pure argon column 20 of FIG. 1 from. The pure argon column has no top condenser here. The crude argon stream 176 is here formed by a part of the return passages of the top condenser 24 of the crude argon column 25 and fed to the top of the pure argon column 20. The top gas 177 of the pure argon column 20 is returned to the top of the crude argon column 25. The residual gas stream 178 is formed by the uncondensed in the top condenser 24 portion of the top gas of crude argon and pure argon. It is removed at the upper end of the return passages via a lateral header and, like the residual gas stream 78 of the FIG. 1 be treated.

FIG. 3 shows only the crude argon column 25 and the pure argon column 20. Otherwise, the method is identical to those of FIGS. 1 and 2 , Similar to FIG. 2 Here is a first Rohargonstrom 276a liquid introduced into the pure argon column 20. Deviating from FIG. 2 However, this introduction is not done on the head, but as in FIG. 1 at an intermediate point of the pure argon column 20. At this point, a part 277 of the ascending in the pure argon gas and withdrawn to the top of the crude argon column 25.

The vapor 276b from the head of the return passages of the top condenser 24 forms a second crude argon stream. This is at least partially condensed in an additional capacitor 227, which is designed as a condenser-evaporator. The condensate 282 is given as reflux to the top of the pure argon column. The evaporation side of the additional capacitor 227 is like that of the top condenser 24 formed as a liquid bath evaporator, both preferably being arranged in the same liquid bath, which is fed by liquid crude oxygen 23.

In FIG. 4 On the one hand, the temperature profile is plotted against the height of the condenser block (left axis). Between the liquid condensing in the return passages whose temperature is approximately equal to the temperature in the evaporation passages (upper curve "condensation") and in countercurrent For ascending evaporating gas (lower curve "evaporation") there is a temperature difference (MTD), which is almost constant over the height of the reflux condenser.

On the other hand, the nitrogen content of the ascending gas in the block is shown. The reflux condenser has assumed in the example a separation effect of five theoretical plates. A theoretical bottom causes in the top condenser of a crude argon column a nitrogen increase by a factor of about 3 (K value of nitrogen in argon).

All described capacitors are preferably designed as soldered aluminum plate heat exchangers whose channels contain corrugated sheets, so-called fins. Within the return passages basically the same types of fins can be used. However, it may be beneficial in reflux condensers to use different Fintypen. An embodiment is in FIG. 5 shown. The return passages shown here are divided into four sections A to D, in which different types of fins are used. In the lower inlet region of the reflux condenser, the gas load and thus the flood tendency is greatest. At the top, the gas load is getting smaller. Therefore, in the lower region A, a fin with a small specific pressure loss and a relatively poor heat transfer is preferably selected. Towards the top, in the areas B, C and D fins are used, each with a greater pressure loss and better heat transfer. For example, the wavelength of the fins (Findichte) increases upward.

FIG. 6 shows a further method to make the operation of the return passages of the reflux condenser 24 so that the basically upward decreasing gas load is compensated. In this case, via line 383, a part of the gas to be condensed is given up on the return passages. This reduces the gas load in the lower zone. Since the amount of gas flowing to the head is only a subset of the amount of gas to be condensed, the necessary piping takes up less space and construction volume is saved.

In a further embodiment, the reflux condenser on the evaporation side is designed as a falling-film evaporator, that is to say vaporizing cooling fluid is added at the top and flows down in a film flow through the evaporation passages. Here, too, results in a particularly favorable course of the evaporation and liquefaction temperatures over the height of the reflux condenser.

Claims (15)

Process for the recovery of argon by cryogenic separation of air, in which - feed air (1) is compressed (3) and introduced into a distillation column system for nitrogen-oxygen separation (13, 14), - an argon-containing stream (72) is taken from the distillation column system for nitrogen-oxygen separation, - the argon-containing stream (72) is fed to a crude argon column (25), the crude argon column (25) has a top condenser (24) formed by at least one plate heat exchanger block having liquefaction passages and evaporation passages, a top gas from the crude argon column (25) is introduced into the liquefaction passages of the top condenser and is at least partially condensed there, - At least a portion of the condensate obtained is given as reflux liquid on the crude argon column (25), the top condenser is the only source of return of the crude argon column, - A liquid cooling fluid is fed to the evaporation passages at a first end and partially evaporated there a mixture of vaporized cooling fluid and liquid remaining cooling fluid is withdrawn from a second end of the vaporization passages, - the crude argon column (25) or the top condenser (24) a Rohargonstrom (76, 176, 276a, 276b) is removed, - The Rohargonstrom (76, 176, 276a, 276b) is fed to a pure argon column (20) and - the pure argon column (20) a pure argon product stream (81) is removed, characterized in that the top condenser (24) of the crude argon column (25) is designed as a reflux condenser and top gas of the crude argon column is introduced into the return passages of the reflux condenser. A method according to claim 1, characterized in that the liquid cooling fluid is supplied to the evaporation passages at its lower end and the mixture of vaporized cooling fluid and liquid remaining cooling fluid is withdrawn from the lower end of the evaporation passages. A method according to claim 1 or 2, characterized in that the top condenser is formed by exactly one plate heat exchanger block. Method according to one of claims 1 to 3, characterized in that the Rohargonstrom (76, 276b) is withdrawn from the upper region of the return passages. Method according to one of claims 1 to 4, characterized in that no residual gas stream is withdrawn from the upper region of the crude argon column (25) and from the return passages. Method according to one of claims 1 to 5, characterized in that the Rohargonstrom (276b) of the crude argon column or the top condenser (24) taken in gaseous form and upstream of its introduction (282) into the pure argon column (20) in an additional capacitor (227) at least partially is condensed. A method according to claim 6, characterized in that the top condenser (24) and the additional condenser (227) are designed as a condenser-evaporator, wherein both evaporation passages with the same cooling fluid (23) are fed. A method according to claim 7, characterized in that the top condenser (24) and the additional condenser (227) formed as a liquid bath evaporator and are arranged in the same liquid bath. Method according to one of claims 1 to 8, characterized in that the crude argon stream (176, 282) is fed in the liquid state to the head of the pure argon column (20). Method according to one of claims 1 to 9, characterized in that withdrawn from the head of the pure argon column (20) or from the upper region of the return passages, a residual gas stream (78, 178, 278) and the feed air, in particular before their compression (3) admixed becomes. Method according to one of claims 1 to 10, characterized in that the return condenser has at least one heat exchanger block, which is designed as a plate heat exchanger. Apparatus for recovering argon by cryogenic separation of air with - An air compressor (3) for the compression of feed air (1), - means for introducing the compressed feed air (8, 10, 12) into a distillation column system for nitrogen-oxygen separation (13, 14), - means for removing an argon-containing stream (72) from the distillation column system for nitrogen-oxygen separation, Means for introducing the argon-containing stream (72) into a crude argon column (25), wherein the crude argon column (25) has a top condenser (24) formed by at least one plate heat exchanger block having liquefaction passages and evaporation passages, - Means for introducing a head gas from the crude argon column (25) in the liquefaction passages of the top condenser, Means for giving up at least part of the condensate recovered in the overhead condenser (24) as reflux liquid to the crude argon column (25), wherein the top condenser is the only source of reflux of the crude argon column, Means for introducing a liquid cooling fluid into the evaporation passages at a first end of the top condenser, Means for withdrawing a mixture of vaporized cooling fluid and liquid remaining cooling fluid from the vaporization passages from a second end of the top condenser, - means for withdrawing a crude argon stream (76, 176, 276a, 276b) from the crude argon column (25) or the top condenser (24), Means for introducing the crude argon stream (76, 176, 276a, 276b) into a pure argon column (20), Means for removing a pure argon product stream (81) from the pure argon column (20), characterized in that the top condenser (24) of the crude argon column (25) is designed as a reflux condenser and means for introducing Head gas of the crude argon column has in the return passages of the reflux condenser. Apparatus according to claim 12, characterized in that the means for introducing a liquid cooling fluid into the evaporation passages at the lower end of the top condenser and the means for withdrawing a mixture of vaporized cooling fluid and liquid remaining cooling fluid from the evaporation passages are arranged at the lower end of the top condenser. Apparatus according to claim 12 or 13, characterized in that the top condenser is formed by exactly one plate heat exchanger block. Device according to one of claims 12 to 14, characterized in that the return condenser has at least one heat exchanger block, which is designed as a plate heat exchanger.

Images