Air separation plant, method for obtaining a product containing argon, and method for creating an air separation plant

Abstract

An air separation plant for obtaining product containing argon by low temperature separation of compressed, cooled feed air. The air separation plant comprises a high-pressure column, a multi-part low-pressure column having a base segment and a head segment and a multi-part crude argon column having a base segment and a head segment. An oxygen-enriched flow is obtained from part of the feed air in the high pressure column, an argon-enriched flow is obtained from part of the oxygen-enriched flow in the low-pressure column, and an argon-rich flow is obtained from part of the argon-enriched flow in the crude argon column. Liquid flow is transferred from a lower region of the head segment of the low-pressure column and from a lower region of the base segment of the crude argon column into an upper region of the base segment of the low-pressure column.

Claims

1. An air separation plant for producing an argon-containing product by low-temperature separation of compressed cooled feed air, said air separation plant comprising: a high-pressure column, a low-pressure column constructed in a multi-piece manner having a foot section and a top section arranged spatially separate therefrom, and a crude argon column constructed in a multi-piece manner having a foot section and a top section arranged spatially separate therefrom, wherein, in the high-pressure column, at least one oxygen-enriched stream is obtainable from at least a part of the feed air, in the low-pressure column at least one argon-enriched stream is obtainable from at least a part of the oxygen-enriched stream, wherein said argon-enriched stream is obtained from a lower part of the top section of the low-pressure column, and in the crude argon column, at least one argon-rich stream is obtainable from at least a part of the argon-enriched stream, a first pipeline for removing at least one liquid stream from a lower region of the top section of the low-pressure column, a second pipeline for removing at least one liquid stream from a lower region of the foot section of the crude argon column, wherein said first pipeline is in direct fluid communication with a shared pump and wherein the second pipeline is in fluid communication with said shared pump, and a third pipeline for transferring the at least one liquid stream from a lower region of the top section of the low-pressure column and the at least one liquid stream from a lower region of the foot section of the crude argon column from the shared pump into an upper region of the foot section of the low-pressure column.

2. The air separation plant as claimed in claim 1, in which the foot section and the top section of the crude argon column are arranged geodetically at least in part next to the top section of the low-pressure column.

3. The air separation plant as claimed in claim 1, in which the foot section or the top section of the crude argon column is arranged geodetically completely above the top section of the low-pressure column.

4. The air separation plant as claimed in claim 1, in which the foot section of the low-pressure column is arranged in vertical plan view next to the top section thereof and/or the foot section of the crude argon column is arranged in vertical plan view next to the top section thereof.

5. The air separation plant as claimed in claim 1, in which the high-pressure column and the foot section of the low-pressure column are arranged in a common cold box.

6. The air separation plant as claimed in claim 1, in which the top section of the low-pressure column and either the foot section or the top section of the crude argon column are arranged in a common cold box.

7. The air separation plant as claimed in claim 6, in which said common cold box is connectable by means of a piping module to further components of the air separation plant.

8. The air separation plant as claimed in claim 1, in which the high-pressure column and the foot section of the low-pressure column are constructed as a structural unit and are in heat-exchange connection to one another via a main condenser.

9. The air separation plant as claimed in claim 1, further comprising a pure argon column, wherein at least one fluid of the pure argon column is coolable by the oxygen-enriched stream.

10. A method for obtaining an argon-containing product by low temperature separation of compressed cooled feed air in an air separation plant, said air separation comprising a high-pressure column, a low-pressure column constructed in multi-part form having a foot section and a top section arranged spatially separate therefrom, and a crude argon column constructed in a multi-part form having a foot section and a top section arranged spatially separate therefrom, said process comprising: introducing at least a part of the feed air into the high-pressure column and obtaining at least one oxygen-enriched stream from the at least a part of the feed air introduced into the high-pressure column, introducing at least a part of the oxygen-enriched stream into the crude argon column and obtaining at least one argon-enriched stream from at least a part of the oxygen-enriched stream introduced into the crude argon column, wherein said argon-enriched stream is obtained from a lower part of the top section of the low-pressure column, obtaining at least one argon-rich stream from at least a part of the argon-enriched stream, and transferring at least one first liquid stream from a lower region of the top section of the low-pressure column via a first pipeline that is in direct fluid communication with a shared pump, transferring at least one second liquid stream from a lower region of the foot section of the crude argon column via a second pipeline that is in fluid communication with said shared pump, and transferring said first and second liquid streams from said a shared pump to an upper region of the foot section of the low-pressure column via a third pipeline.

11. The method as claimed in claim 10, in which the foot section and the top section of the crude argon column are arranged geodetically at least in part next to the top section of the low-pressure column.

12. The method as claimed in claim 10, in which the foot section or the top section of the crude argon column is arranged geodetically completely above the top section of the low-pressure column.

13. A method for generating an air separation plant, said method comprising: providing a high-pressure column, a low-pressure column constructed in a multi-part manner having a foot section and a top section, and a crude argon column constructed in a multi-part manner having a foot section and a top section, and providing a shared pump by means of which at least one liquid stream from a lower region of the top section of the low-pressure column and at least one liquid stream from a lower region of the foot section of the crude argon column are directly transferred to an upper region of the foot section of the low-pressure column.

14. The method as claimed in claim 13, in which the foot section and the top section of the crude argon column is arranged geodetically at least in part next to the top section of the low-pressure column.

15. The method as claimed in claim 13, in which the foot section or the top section of the crude argon column is arranged geodetically completely above the top section of the low-pressure column.

16. The air separation plant as claimed in claim 1, in which the foot section or the top section of the crude argon column is arranged geodetically at least in part next to the top section of the low-pressure column.

17. The air separation plant as claimed in claim 1, in which the foot section of the low-pressure column is arranged in vertical plan view next to the top section thereof.

18. The air separation plant as claimed in claim 1, in which the foot section of the crude argon column is arranged in vertical plan view next to the top section thereof.

19. The air separation plant as claimed in claim 10, in which the foot section or the top section of the crude argon column arranged geodetically at least in part next to the top section of the low-pressure column.

20. The method as claimed in claim 13, in which the foot section or the top section of the crude argon column is arranged geodetically at least in part next to the top section of the low-pressure column.

21. The method according to claim 10, wherein said at least one argon-enriched stream is removed from the top section of the low-pressure column.

22. The method according to claim 21, wherein said at least one argon-enriched stream is introduced into the foot section of the crude argon column.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows schematically an air separation plant for obtaining an argon product according to a particularly preferred embodiment of the invention.

(2) FIG. 2 shows schematically an air separation plant for obtaining an argon product according to a particularly preferred embodiment of the invention.

EMBODIMENTS OF THE INVENTION

(3) In the figures, elements corresponding to one another are given identical reference signs. Repeated explanation of the same is dispensed with.

(4) It is stressed explicitly that the arrangement of the components of the air separation plants shown in FIGS. 1 and 2 is only by way of example and that, in particular, the dimensions of the components shown there, in particular the columns, are not correct to scale. As mentioned, the crude argon column of a corresponding air separation plant generally has the greatest height, which is not reproduced correct to scale in the drawing. Also plants having what are termed dummy columns are known, from which only argon is taken off in order to achieve an energy advantage. Such columns are markedly lower, that is to say also lower than the other columns.

(5) FIG. 1 shows schematically an air separation plant according to the invention for obtaining an argon product and which is denoted overall with 100. The air separation plant, as separation units, has a high-pressure column 1, a two-piece low-pressure column having a foot section 2 and a top section 3, an equally two-piece crude argon column having a toot section 4 and a top section 5, and also a pure argon column 6. The foot section 2 and the top section 3 of the low-pressure column are structurally separated from one another. The top section 3 of the low-pressure column is arranged in vertical plan view next to the high-pressure column 1, and the foot section 2 of the low-pressure column thereabove. The foot section 2 and the top section 3 of the low-pressure column correspond together functionally to a conventional low-pressure column of a Linde twin column. The high-pressure column 1 and the two column sections 2 and 3 of the low-pressure column therefore form a distillation column system for nitrogen-oxygen separation.

(6) In the exemplary embodiments shown, cooled and compressed feed air is fed into the high-pressure column 1 in the form of two streams a and b. The streams a and b can be what is termed a turbine stream (stream a) on the one hand and what is termed a throttle stream (stream b) on the other. The air separation plant 100 according to the invention can therefore be constructed for internal compression. Providing the streams a and b is shown, for example, in EP 2 026 024 A1. For example, atmospheric air can be drawn in by suction via a filter from an air compressor and there be compressed to an absolute pressure from 5.0 to 7.0 bar, preferably about 5.5 bar. The air can be compressed to a higher pressure in the air compressor itself or in a further compressor (aftercompressor) arranged downstream therefrom and later expanded via an expansion engine, as a result of which, for example, some of the refrigeration requirement of the air separation plant 100 can be covered.

(7) The air can be cooled after the compression, for example in a direct contact cooler in direct heat exchange with cooling water. The cooling water can be supplied, tor example, from an evaporative cooler and/or from an external source. The compressed and cooled air can then be purified in a purification device. This can have, for example, a pair of containers which are filled with a suitable adsorbent, preferably molecular sieve. The purified air is then generally cooled in a main heat exchanger to about dew point.

(8) The operating pressuresin each case at the top or at the upper part of the top sectionare 4.5 to 6.5 bar, preferably about 5.0 bar in the high-pressure column 1 and 1.2 to 1.7 bar, preferably about 1.3 bar, in the low-pressure column 2, 3. The foot section 2 and the top section 3 of the low-pressure column are preferably operated at substantially the same pressure, which, however, does not exclude certain pressure differences, for example owing to line resistances.

(9) The high-pressure column 1 and the foot section 2 of the low-pressure column are in heat-exchange connection via a main condenser 12 and are constructed as a structural unit. However, the invention is fundamentally also usable in systems in which the high-pressure column 3 and the low-pressure column (or the foot section 2 thereof) are arranged separate from one another and have a separate main condenser, i.e. one which is not integrated into the columns.

(10) Air which is liquefied when the feed air stream b is fed into the high-pressure column 1 can in part be removed as corresponding stream c, warmed in a subcooling counterflow heat exchanger 13 and then used in other ways or again compressed and provided as feed air stream a, b.

(11) An oxygen-enriched fraction d is taken off from the sump of the high-pressure column 1, subcooled in the subcooling counterflow heat exchanger 13 and, as stream e, further cooled in part in a sump evaporator 14 of the pure argon column 6. Another part can bypass the sump evaporator 14. Part of the stream e flows into the evaporation chamber of an overhead condenser 15 of the top section 5 of the two-part crude argon column, another part into the evaporation space of an overhead condenser 16 of the pure argon column 6. The portion of the oxygen-enriched fraction that is vaporized in the overhead condensers 15 and 16 is fed as stream f to the top section 3 of the low-pressure column at a first intermediate point. The portions remaining liquid are applied as stream g at a second intermediate point of the top section 3 of the low-pressure column which is situated above the first intermediate point.

(12) Gaseous nitrogen from the top of the high-pressure column 1 can be warmed, in part as stream h, for example in the main heat exchanger which is not shown, for cooling the feed air to about ambient temperature, and then, as shown in EP 2 026 024 A1, be treated further.

(13) The residual gaseous nitrogen from the top of the high-pressure column 1 is at least partly condensed in the main condenser 12. The liquid nitrogen generated in the course of this operation is in part applied as reflux to the high-pressure column 1. Another part, after subcooling in the subcooling counterflow heat exchanger 13, is passed as stream i to the upper part of the top section 3 of the low-pressure column. A gaseous nitrogen stream j from the top of the top section 3 of the low-pressure column can, after passing through the subcooling counterflow heat exchanger 13, be utilized in a different manner, or reused in the air separation plant.

(14) A liquid oxygen stream k from the sump of the foot section 2 of the low-pressure column can be pressurized in the liquid state by means of a pump 17 and then passed, for example, to a liquid oxygen tank (LOX). Some of this oxygen can also be vaporized for providing gaseous pressurized oxygen (what is termed internal compression).

(15) The division of the low-pressure column into the foot section 2 and the top section 3 and operation thereof proceed in such a manner that, in the lower part of the top section 3 of the low-pressure column, an argon-enriched fraction accumulates, in this case this is the region of what is termed the argon transition (also designated argon bubble or argon section). This enrichment results, as is known to those skilled in the art, from the volatility of argon which lies between that of nitrogen and that of oxygen. If customary reflux ratios are used in the low-pressure column, the argon transition lies above and below the intermediate point at which an oxygen-enriched fraction is fed in (streams f and g). Argon concentrations of up to 15% in the vapor phase can be achieved. In order to reduce the nitrogen concentration, the argon-enriched stream, however, is usually taken off below this intermediate point, as is here the case (stream m).

(16) In the air separation plant 100, a stream 1 flows from the upper part of the foot section 2 of the low-pressure column to the top section 3 of the low-pressure column in the lower region thereof as a result of which the foot section 2 and the top section 3 of the low-pressure column are in part functionally coupled. At the same height, from the top section 3 of the low-pressure column, an argon-rich stream m is taken off and fed into the foot section 4 of the crude argon column. The feed-in proceeds immediately above the sump of the foot section 4 of the crude argon column.

(17) Sump liquid from the sump of the top section 3 of the low-pressure column and from the sump of the foot section 4 of the crude argon column is passed back via a pump 18 as stream n to the foot section 2 of the low-pressure column. As a result, firstly the functional coupling of the first column section 2 and of the second column section 3 of the low-pressure column is completed and, secondly, the crude argon column is incorporated into the separation system via the foot section 4.

(18) The overhead condenser 15 of the top section 5 of the crude argon column can be constructed as a reflux condenser. Gas from the top end of the top section 5 of the crude argon column flows downwards into the reflux passages and is there partially condensed. The condensate that is generated as a result flows downwards in counterflow to the ascending gas in the reflux passages and is utilized in the top section 5 of the crude argon column as liquid reflux. On the evaporation side, the overhead condenser 15 is constructed as a bath condenser. The coolant fluid, which is formed here by the liquid oxygen-enriched fraction from the high-pressure column 1, flows downwards via one or more side openings into the evaporation passages and there in part vaporizes. The thermo siphon effect entrains liquid, which exits together with the vaporized portion at the upper end of the evaporation passages and is returned to the liquid bath. The overhead condenser 15 is therefore constructed on the evaporation side as a bath evaporator.

(19) From the top end of the reflux passages, via a lateral header, a crude argon stream n is withdrawn in the gaseous state and passed to the pure argon column 6 at an intermediate site. The overhead condenser 16 of the pure argon column 6 is, in the example, conventionally constructed on the liquefaction side, i.e. an overhead gas stream o of the pure argon column 6 flows from top to bottom through the liquefaction passages. (Alternatively, the overhead condenser 16 of the pure argon column 6 and/or the main condenser 12 could also be constructed as reflux condensers.) A residual gas stream p is taken off from the overhead condenser 16 of the pure argon column 6 and blown off to atmosphere (ATM) in the example. Alternatively, it can be recirculated via a separate fan into the high-pressure column 1 or the low-pressure column 2, 3 and/or upstream of the air compressor.

(20) The sump liquid of the pure argon column 6 is in part vaporized as stream p in the sump evaporator 14 and the vapor generated in this ease is utilized as ascending gas in the pure argon column 6. The remainder is withdrawn as liquid pure argon product stream q (LAR).

(21) An exemplary integration of the components of the air separation plant 100 in corresponding cold boxes is shown in FIG. 1 by dashed lines. In this case, A denotes a first cold box which is designed for receiving the high-pressure column 1 and the foot section 2 of the low-pressure column. A second cold box B can be designed for receiving the top section 3 of the low-pressure column. In the example shown, a third cold box C is designed for receiving the top section 5 of the erode argon column. As explained, the top section 3 of the low-pressure column and the top section 5 of the high-pressure column (optionally together with the pure argon column 6) can also be arranged in a shared cold box. Such a cold box can have, for example, a height of 40 m. A fourth cold box D is shown reduced in the example given and, for example, likewise has a height of 40 m.

(22) In FIG. 2, an air separation plant for obtaining an argon product according to a further embodiment of the invention is shown in a still more diagrammatic form. In this air separation plant, only the columns 2 to 6 are shown, and a depiction of the corresponding connections, pumps and heat exchangers has been substantially dispensed with. As can be seen, here, in contrast to the depiction of FIG. 1, a foot section 4 of the crude argon column is arranged above the top section 3 of the low-pressure column. In this alternative embodiment, the subdivision of the crude argon column can be performed at a site different from that shown in the figure, if this is expedient for the arrangement according to the invention. Here also, the advantage results that fluid from the foot, section 4 of the crude argon column and from the top section 3 of the low-pressure column can be pumped by means of the pump 18 as stream n into the foot section 3 of the low-pressure column. This also applies to arrangements that are provided as an alternative in which the foot section 4 and/or the top section 5 of the crude argon column is geodetically arranged at least in part next to the top section 3 of the low-pressure column. Also, all column sections 1 to 4 can be arranged at least in part geodetically adjacent to one another.

(23) In all of the cases shown, via the choice of the internals in the respective columns (sieve trays, packings having differing density), the diameter of the columns can be correspondingly influenced and hereby optionally a further structural adaptation can be achieved.