EP3870915A1 - Method and unit for low-temperature air separation - Google Patents

Abstract

The invention relates to a method for a low-temperature air separation in which an air separation unit (100, 3100) is used comprising a first rectification column (11) and a second rectification column (12). The first rectification column (11) is operated at a first pressure level, and the second rectification column (12) is operated at a second pressure level below the first pressure level. Fluid which is oxygen-enriched compared to atmospheric air is drawn from the first rectification column (11) in the form of one or more first material flows. At least one fraction of the fluid which has been drawn from the first rectification column (11) in the form of the one or more first material flows is heated in a heat exchanger (2); a fraction of the fluid which has been heated in the heat exchanger (2) is compressed using a compressor (5) and is returned to the first rectification column (11); a first fraction of the head gas of the first rectification column (11) is condensed in the heat exchanger (2), and a second fraction is discharged from the air separation unit (100, 3100) in the form of at least one nitrogen-enriched air product; Additional fluid which contains oxygen, nitrogen, and argon is drawn from the first rectification column (11) and is used as a second material flow or to form a second material flow, which is transferred to the second rectification column (12); an oxygen-enriched sump liquid is formed in the sump of the second rectification column (12); and at least one fraction in the form of a third material flow is discharged from the air separation unit (100, 200). According to the invention, a third rectification column (13) is used, said second rectification column (12) and third rectification column (13) being designed as parts of a double column such that the third rectification column (13) is arranged below the second rectification column (12) and such that the third rectification column (14) is supplied with air. The invention likewise relates to a corresponding unit (100-3100).

Description

 description

Process and plant for the low-temperature zea sauna of air

The invention relates to a method for the low-temperature separation of air and a corresponding system according to the preambles of the independent claims.

State of the art

The production of air products in liquid or gaseous state by low-temperature separation of air in air separation plants is known and

for example at H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH,

2006, in particular Section 2.2.5, "Cryogenic Rectification".

Air separation plants have rectification column systems that

conventionally, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three- or

Multi-column systems can be formed. In addition to the rectification columns for the production of nitrogen and / or oxygen in the liquid and / or gaseous state, that is to say the rectification columns for the nitrogen-oxygen separation, rectification columns for the production of further air components, in particular the noble gases krypton, xenon and / or argon, can be provided. The terms "rectification" and "distillation" as well as "column" and "column" or terms composed thereof are frequently used synonymously.

The rectification columns of the rectification column systems mentioned are operated at different pressure levels. Known double-column systems have a so-called high-pressure column (also referred to as a pressure column, medium-pressure column or lower column) and a so-called low-pressure column (also referred to as the upper column). The high pressure column is typically on a

Pressure level of 4 to 7 bar, in particular about 5.3 bar, operated. The

Low pressure column is operated at a pressure level of typically 1 to 2 bar, in particular approximately 1, 4 bar. In certain cases, both can

Rectification columns can also be used at higher pressure levels. With the here and the pressures given below are absolute pressures at the top of the respective columns.

So-called SPECTRA processes are known from the prior art for providing pressurized nitrogen as the main product. These are explained in detail below. In embodiments, the present invention sets itself the task of improving such SPECTRA processes, primarily with regard to energy consumption and material yield. A main focus of the object placed on the present invention is in particular to specify a method and an air separation plant, by means of which, in addition to larger amounts of high-purity, gaseous nitrogen, clearly on one

A further nitrogen product and / or argon can also be provided in an advantageous manner above the atmospheric pressure level.

Disclosure of the invention

Against this background, the present invention proposes a method for

Cryogenic air separation and a corresponding system with the features of the independent claims. Preferred embodiments are the subject of the dependent claims and the following description.

Before the features and advantages of the present invention are explained, some basics of the present invention are explained in more detail and terms used below are defined.

The devices used in an air separation plant are described in the technical literature cited, for example from Häring (see above) in Section 2.2.5.6, "Apparatus". If the following definitions do not deviate from this, express reference is made to the cited technical literature for the language used in the context of the present application.

Liquids and gases can be rich or poor in one or more components in the parlance used here, "rich" for a content of at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% and "poor" for a content of at most 25%, 10%, 5%, 1%, 0.1% or 0.01% on mole, weight or Volume basis can stand. The term "predominantly" can correspond to the definition of "rich". Liquids and gases can also be enriched or depleted in one or more components, these terms refer to a content in a starting liquid or gas from which the liquid or gas was obtained. Be the liquid or the gas

"Enriched" if this or this at least 1, 1 times, 1, 5 times, 2 times, 5 times, 10 times 100 times or 1,000 times salary, and "depleted" if this or this contains at most 0.9 times, 0.5 times, 0.1 times, 0.01 times or 0.001 times the content of a corresponding component, based on the starting liquid or gas. If, for example, "oxygen", "nitrogen" or "argon" is mentioned here, this should also be understood to mean a liquid or a gas which is rich in oxygen or nitrogen, but does not necessarily have to consist exclusively of it.

The present application uses to characterize pressures and

Temperatures are the terms "pressure level" and "temperature level", which is intended to express that corresponding pressures and temperatures in a corresponding system do not have to be used in the form of exact pressure or temperature values in order to implement the inventive concept. However, such pressures and temperatures are typically in certain ranges, for example ± 1%, 5%, 10% or 20% around an average. Corresponding pressure levels and temperature levels can lie in disjoint areas or in areas that overlap one another. In particular, pressure levels include, for example, unavoidable or expected pressure drops. The same applies to temperature levels. For those given here in cash

Pressure levels are absolute pressures.

If "relaxation machines" are mentioned here, they are typically understood to be known turbo expanders. These expansion machines can in particular also be coupled to compressors. These compressors can in particular be turbocompressors. A corresponding combination of turboexpander and turbocompressor is typically also referred to as a "turbine booster". In a turbine booster, the turboexpander and the turbocompressor are mechanically coupled, the coupling being the same speed (for example via a common shaft) or different in speed (for example using a suitable one gear). The term "compressor" is generally used here. A "cold compressor" here designates a compressor to which a fluid flow at a temperature level significantly below 0 ° C, in particular below -50, -75 or -100 ° C and up to -150 or -200 ° C is supplied. A corresponding fluid flow is cooled in particular to a corresponding temperature level by means of a main heat exchanger (see immediately).

A "main air compressor" is characterized by the fact that it compresses all of the air that is supplied to the air separation system and that is separated there. On the other hand, in one or more optionally provided additional compressors, for example post-compressors, only a portion of this air which has already been compressed in the main air compressor is compressed further. Accordingly, the "main heat exchanger" of an air separation plant represents the heat exchanger in which at least the

predominant portion of the air supplied to the air separation plant and cooled there is cooled. This takes place, at least in part, in counterflow to material flows which are discharged from the air separation plant. From an air separation plant

"Derived" material flows or "products" are, in the language used here, fluids that no longer participate in internal system cycles, but are permanently withdrawn from them.

A "heat exchanger" for use in the context of the present invention can be designed in a manner customary in the art. It is used for the indirect transfer of heat between at least two e.g. Fluid flows guided in countercurrent to one another, for example a warm compressed air flow and one or more cold ones

Fluid flows or a cryogenic liquid air product and one or more warm or warmer, but possibly also cryogenic fluid flows. A

Heat exchanger can be formed from a single or several heat exchanger sections connected in parallel and / or in series, e.g. from one or more plate heat exchanger blocks. For example, it is a

Plate Fin Heat Exchanger. Such a heat exchanger has "passages" which are separated from one another by fluid channels

Heat exchange surfaces are formed and in parallel and separated by other passages to "passageway groups". Characteristic of a

Heat exchanger is that it has heat between two mobile at a time Media is exchanged, namely at least one fluid stream to be cooled and at least one fluid stream to be heated.

A "condenser evaporator" is a heat exchanger in which a first, condensing fluid stream enters into indirect heat exchange with a second, evaporating fluid stream. Each condenser evaporator has one

Liquefaction room and an evaporation room. Liquefaction and

Evaporation rooms have liquefaction or evaporation passages. The condensation (liquefaction) of the first fluid flow is carried out in the liquefaction space, and the evaporation of the second fluid flow is carried out in the evaporation space. The evaporation and liquefaction space are formed by groups of passages that are in heat exchange relationship with each other.

The relative spatial terms "above", "below", "above", "below", "above",

"Below", "next to", "next to each other", "vertical", "horizontal" etc. refer here to the spatial orientation of the rectification columns of an air separation plant in normal operation. An arrangement of two rectification columns or other components "one above the other" is understood here to mean that the upper end of the lower of the two parts of the apparatus is at a lower or the same geodetic height as the lower end of the upper of the two parts of the apparatus and the projections of the two parts of the apparatus are in one intersect horizontal plane. In particular, the two parts of the apparatus are arranged exactly one above the other, that is to say the axes of the two parts of the apparatus run on the same vertical straight line. However, the axes of the two parts of the apparatus need not lie exactly vertically one above the other, but can also be offset from one another, in particular if one of the two parts of the apparatus, for example a rectification column or a

Column part with a smaller diameter should have the same distance from the sheet metal jacket of a cold box as another with a larger diameter.

The present invention comprises the low-temperature separation of air according to the so-called SPECTRA method, as described, inter alia, in EP 2 789 958 A1 and the other patent literature cited therein. In its simplest form, this is a single-column process. Such processes enable a high nitrogen yield. A return to a rectification column, which in the simplest case is the only one, is achieved by condensing top gas Rectification column, more precisely a part of this top gas, provided in a heat exchanger. Fluid that is taken from the same rectification column is used for cooling in the heat exchanger. Additional head gas can be provided as a nitrogen-rich product of the process or the system.

A part of the fluid which was used to condense the part of the top gas treated in this way is compressed by means of a cold compressor and returned to the same rectification column. Very favorable air factors can be achieved with the SPECTRA process, i.e. a large amount of product per amount of air used. A corresponding method is first explained in more detail below. The term "SPECTRA method" is intended to explain the above

Single column process for nitrogen production or a modified one

Act single-column process in which, as also explained below, a further rectification column is used for the production of oxygen.

As with other low-temperature air separation processes, the SPECTRA process cools compressed and pre-cleaned air to a temperature suitable for rectification. This can partially liquefy it. The air is then fed into the rectification column just mentioned and rectified there under the typical pressure of a high-pressure column, as explained at the outset, to obtain the top gas which has already been enriched in nitrogen with respect to atmospheric air and a liquid bottom liquid which is enriched in oxygen with respect to atmospheric air.

In the case of a SPECTRA process, this is what happens in an air separation plant

Rectification column mentioned used in which a gaseous top product enriched with nitrogen in relation to atmospheric air and a liquid bottom product enriched with oxygen in relation to atmospheric air are formed on the one hand. The terms "top product" and "top gas" on the one hand and "bottom product" and "bottom liquid" on the other hand are used synonymously here.

This rectification column, the top gas of which is partly liquefied or partly liquefied in the manner described using expanded fluid from the same rectification column and then at least partly on the same Rectification column is referred to here as the "first" rectification column. As mentioned, this can also be the only rectification column in known SPECTRA processes. However, this is not the case in the context of the present invention.

From the first rectification column, the fluid which is used to condense the portion of the top gas of the first rectification column treated in this way and which can be in particular cryogenic liquid which is oxygen-enriched with respect to atmospheric air, in the form of one or more material flows taken. At least part of it is heated in the heat exchanger, which is used to condense the part of the top gas of the first rectification column treated in this way.

This or these material flows is or are referred to below as the "first" material flow or "first" material flows. The fluid can only be in the form of a first

Material flow or in the form of two or more separate first material flows through the heat exchanger. For example, a material stream can first be removed from the rectification column and then divided, or two separate first material streams, in particular with different oxygen contents, can already be removed from the rectification column separately.

In the SPECTRA process, as already mentioned and here again expressed in other words, the fluid is that of the first

Rectification column in the form of one or more first material streams removed and heated in the heat exchanger, compressed to a first part in one or more compressors and fed back into the first rectification column after this compression.

In a second part, the fluid which is taken from the first rectification column in the form of the one or more first material streams and in which

Heat exchanger is heated, relaxed in the SPECTRA process using one or more expansion machines and in particular as a so-called residual gas mixture from the air separation plant. The first and second part of the fluid which is removed from the rectification column in the form of the one or more first material flows, i.e. the compressed and the relaxed part, can in turn be two first material flows, as explained above, which are already separate from the first Rectification column, however, can also be portions of only one first stream taken from the first rectification column. The first and second part can also have been passed through the heat exchanger together and only then divided into the first and second part.

For the compression of the mentioned first part of the fluid, that of the first

Rectification column in the form of one or more first streams removed and heated in the heat exchanger, can or can

in particular one or more compressors are used, which is or are coupled to one or more expansion machines. In the expansion machine or machines, in particular the expansion of the mentioned second part of the fluid, which is taken from the first rectification column in the form of the one or more first material flows and heated in the heat exchanger, can be carried out. However, it goes without saying that only parts of the first and second portions in the correspondingly coupled units are compressed or

can be relaxed. A relaxation machine that is not coupled to a corresponding compressor can, if present, be braked in particular mechanically and / or by means of a generator. Braking is also an option

Relaxation machine possible, which is coupled to a compressor.

For example, a compressor can be used, which is coupled to one of two expansion machines arranged in parallel. Will only be one

Used expansion machine, the compressor can be coupled to this. The wording used below merely for reasons of clarity, according to which "a" compressor is coupled to "a" expansion machine, does not exclude the use of several compressors and / or expansion machines in any mutual coupling. However, the compressor or compressors described does not have to be driven, in particular not exclusively, by means of the one or more expansion machines mentioned.

Conversely, the compressor or compressors do not have to have all of them

Take up work that becomes free of relaxation. As also in the following on one Illustrated as an example, a supporting or exclusive drive can also take place using an electric motor, or a brake can be interposed between the expansion machine or machines and the compressor (s).

The compressor or compressors are one or more cold compressors, since this or these is the first portion of the fluid that is taken from the rectification column in the form of the one or more first material flows and in the

Heat exchanger is heated, despite this heating and a possibly

subsequent further heating to a correspondingly low level

Temperature level is supplied.

Instead of the explained relaxation of the second part of the fluid that the

Rectification column in the form of the one or more first material flows and is heated in the heat exchanger, and its described discharge from the air separation plant, can also be based on a corresponding one

Relaxation can be dispensed with and / or this second part can, with or without relaxation, be fed into one or more further rectification columns, as will be explained further below.

In a more specific embodiment of a SPECTRA process, two first material flows in the form of a liquid can be obtained from the first rectification column

Material stream with a first oxygen content and a liquid material stream with a second, higher oxygen content are deducted. The first stream of material with the first (lower) oxygen content can be withdrawn from the first rectification column from an intermediate plate or from a liquid retention device. The second stream with the second (higher) oxygen content can in particular be formed using at least part of the liquid bottom product of the first rectification column.

The first material flow with the first (lower) oxygen content can in particular form the previously explained first part of the fluid, that of the first

Rectification column is removed in the form of the one or more first material flows and heated in the heat exchanger, which is used to condense the portion of the top gas of the first rectification column treated in this way is used. The first material flow with the first (lower) oxygen content can thus form the first part, which is compressed after use in the one or more compressors, and which afterwards into the first

Rectification column is fed back.

The first stream of material with the second (higher) oxygen content, on the other hand, can in particular form the previously explained second part of the fluid, which is removed from the first rectification column in the form of the one or more first streams of material and heated in the heat exchanger, which is used to condense the in this way treated part of the top gas of the first rectification column is used. The first material flow with the second (higher) oxygen content can thus form the second part which is compressed after use in the one or more compressors, and which afterwards into the first

Rectification column is fed back.

In the SPECTRA processes mentioned, so-called oxygen columns can also be used to obtain pure or high-purity oxygen, which are operated at the pressure level of typical low-pressure columns explained at the beginning. A corresponding oxygen column is also referred to below as the "second" rectification column.

Further fluid from the first rectification column is fed into such a second rectification column. This further fluid contains oxygen, argon and nitrogen and is withdrawn in liquid form from the first rectification column in the form of (at least) another stream (hereinafter referred to as "second" stream). In the exemplary embodiment just explained with two "first" material flows with different oxygen contents, the second material flow is in particular above the first material flow with the first (lower)

Oxygen content removed.

While the SPECTRA process was originally intended to provide gaseous nitrogen at the pressure level of the first rectification column, the use of an oxygen column of the type explained in a corresponding process enables the additional production of pure oxygen. Advantages of the invention

The present invention is based on the finding that a process of the type explained above can be modified particularly advantageously by the fact that the oxygen column just explained, that is to say a second rectification column used in a modified SPECTRA process, is formed as part of a double column which in addition to a third in the second rectification column

Rectification column comprises, which is arranged as part of the double column below the second rectification column, and softer air is supplied. The present invention therefore provides an air feed in a SPECTRA process not only into the first column, but also into the third column.

Overall, the present invention proposes, in the language of the

Claims, a method for low-temperature separation of air, in which an air separation plant with a first rectification column and a second rectification column is used. The first rectification column is operated at a first pressure level and the second rectification column at a second pressure level below the first pressure level.

Such first and second pressure levels are typical

Pressure levels, such as those used in conventional air separation plants, especially SPECTRA plants with oxygen generation. The first

Pressure level can be in particular 7 to 12 bar, the second pressure level in particular 1, 2 to 5 bar. The second pressure level can generally be 1 to 4 bar. They are absolute pressures at the head of each

Rectification columns. The first rectification column and the second

Rectification columns can in particular be arranged next to one another and are typically not combined with one another in the form of a double column, in which case a "double column" is generally understood to mean a separating apparatus which is formed from two rectification columns and is constructed as a structural unit in which the column jackets of the two rectification columns are line-less, ie are directly connected to one another, in particular welded. However, no fluid connection has yet to be established by this direct connection alone. The first rectification column used in the context of the present invention and the second used in the context of the present invention

Rectification columns have already been described in detail with reference to the SPECTRA method. The second rectification column can in particular be an oxygen column.

Atmospheric air which has been compressed and then cooled is fed to the first rectification column. In particular, appropriate air can be fed to the first rectification column in the form of a plurality of material streams which are treated differently and, if appropriate, can be passed through further apparatus beforehand. The air fed into the first rectification column can be fed in, in particular, in the form of a liquefied substream and a non-liquefied substream. Further refinements of the air feed, which can be used in particular in the context of the present invention, are explained in more detail below. In contrast, typically no air is fed to the second rectification column; more generally speaking, the second

Rectification column typically not fed material streams that have not previously been taken from another rectification column or formed from such material streams.

As already explained in more detail above, fluid which is enriched in oxygen in relation to atmospheric air is removed from the first rectification column in the form of one or more first material flows. As explained above with regard to the more specific exemplary embodiment of a SPECTRA method, this can in particular involve two first material flows with different ones

Act oxygen levels. Reference is therefore expressly made to the more detailed explanations above.

At least a portion of the fluid that was withdrawn from the first rectification column in the form of the one or more first material streams is heated in a heat exchanger in the context of the present invention, and again a portion thereof, i.e. the fluid that is heated in the heat exchanger (and previously in the form of the one or more first streams from the first rectification column) (previously referred to as "first part"), is compressed in the context of the present invention using a compressor and into the first Rectification column returned. In particular, several compressors can also be used in this context, as mentioned. The feed back into the first rectification column takes place in particular in the form of a feed back into a bottom area of the first rectification column.

The heat exchanger is used for cooling and condensation or partial condensation of overhead gas from the first rectification column, at least some of which is returned to the first rectification column as reflux. In this context, the top gas of the first rectification column is (partially) condensed to a first portion in the heat exchanger (and at least a portion of this in turn is returned to the first rectification column as reflux). A second portion of the overhead gas is discharged from the process or the plant as at least one nitrogen-rich air product.

This at least one air product, such as the overhead gas from the first rectification column from which it was formed, has a certain residual oxygen content, which can be in particular 0.001 to 10 ppm. For example, corresponding top gas can be made available in liquefied form as a gaseous nitrogen product at the first pressure level mentioned. This nitrogen product is a main product of the proposed method. It can be used in particular in one

The main heat exchanger of the air separation plant is warmed up to ambient temperature and then made available at the first pressure level. However, a portion of the overhead gas can also be provided as a liquid nitrogen product of the process or of the system, in particular after subcooling against a further portion, which is then discarded in particular.

As already explained, in the context of the present invention, in addition to the non-liquefied overhead gas as the main product, oxygen, in particular high-purity oxygen, is also provided as the air product. In configurations, argon can also be provided as a product of the method.

A further portion of the fluid which has been heated in the heat exchanger (and which was previously taken in the form of the one or more first streams from the first rectification column) (previously referred to as "second part") can be expanded in the manner explained in the context of the present invention and for example from the Air separation plant to be rejected. For further details, reference is expressly made to the above explanations in this connection. In particular, one or more expansion machines used here can be coupled to the compressor or compressors mentioned above. In this regard, too, reference is made to the above explanations.

It should be understood that, when we are talking about a heat exchanger that is used for cooling or (partial) condensation of the first portion of the top gas of the first rectification column, this heat exchanger differs from

Main heat exchanger of the air separation plant differs and is designed in particular as a separate structural unit. The main heat exchanger of the

As already mentioned, the air separation plant is characterized in particular by the fact that it cools all or at least most of the air supplied to the air separation plant as a whole. However, this is not the case in the heat exchanger in which the first portion of the top gas of the first rectification column is cooled or (partially) condensed, and through which the first material stream (s) are at least partially led.

As mentioned, the method proposed according to the invention is a SPECTRA method with additional oxygen production. In this case, further fluid, which contains oxygen, nitrogen and argon, is therefore removed from the first rectification column. This further fluid is used as a second stream or to form a second stream which is transferred to the second rectification column. An oxygen-rich bottoms liquid is formed in the bottom of the second rectification column and at least a portion in the form of a third stream from the second rectification column or the

Air separation plant rejected overall. This oxygen-rich liquid has in particular a residual nitrogen content, as will be explained in more detail below.

The argon content of the further fluid, which is removed from the first rectification column and used as the second stream or to form the second stream which is transferred to the second rectification column, is in particular 2 to 4 mol percent, and its oxygen content is in particular 10 to 30 Mole percent. The argon content of this fluid depends in particular on the removal height from the first rectification column, which is therefore more suitable Way is chosen. The extraction height of this fluid and thus the second

As mentioned, the material flow is typically above the removal height (s) of the fluid, which is carried out in the form of the one or more first material flows from the first rectification column. The separating trays located in the first rectification column between the corresponding removal points also block hydrocarbons in particular. Therefore, these withdrawal heights are advantageously selected with a view to this aspect, so that the oxygen product obtained has the required purity with regard to hydrocarbons.

As also explained in detail below and before mentioned briefly above, one is included in the scope of the present invention

Double column system are used, the upper part of the second

Rectification column, and the lower part here as "third"

Rectification column is called. In this case, the further fluid which is removed from the first rectification column can, for example, also initially be fed into this third rectification column. In this case, however, liquid is withdrawn from the third rectification column and into the second rectification column immediately below the feed point

Rectification column fed. The second stream of material or corresponding fluid is thus here, as it were, "via the detour" via the third rectification column into the second rectification column. However, such a case is also covered by the statement that fluid which contains oxygen, nitrogen and argon is removed from the first rectification column and used "to form" the second stream. The second stream can also be a direct, i.e. without going through another rectification column, into the second

Rectification column transferred material stream act, in which case that from the first rectification column in the language used here "as" the second material flow is used.

Any further fluid exchange between the first and second

Rectification column is possible, especially to balance the liquid balance. These measures do not limit the invention.

According to the invention, as already mentioned, a third rectification column is used, the second rectification column and the third rectification column are formed as parts of a double column, the third rectification column being arranged below the second rectification column in the sense explained and the third rectification column being fed with air. Regarding the term "double column", reference is made to the above explanations.

The third rectification column is in particular at a pressure level between the first and the second pressure level, that is between the

Operating pressure levels of the first and second rectification columns operated. This pressure level is in particular 4 to 7 bar, in particular approximately 5.5 bar absolute pressure. Air is fed to the third rectification column, which was previously compressed and cooled, and in particular by means of a further one

Expansion machine can be expanded to the pressure level at which the third rectification column is operated. The air with which the third

Rectification column is fed, ie comprises compressed and cooled air, which is expanded using a flash machine.

In the process according to the invention, the second rectification column can be operated with a condenser evaporator which is arranged in a bottom region of the second rectification column and which is heated using fluid which is removed and / or fed to the third rectification column. In this way, particularly efficient processes can be implemented.

In particular, the air, which may be expanded by means of the expansion machine and with which the third rectification column is fed, can be at least partially liquefied in the condenser evaporator, which is arranged in the bottom region of the second rectification column, and returned to the third rectification column as a liquid reflux.

In the condenser evaporator, which is in the bottom area of the second

Rectification column can be arranged, top gas of the third

Rectification column at least partially liquefied and returned to the second or third rectification column as reflux. In other words, a gaseous top product of the third rectification column can be used to heat a condenser evaporator of the second rectification column, the liquid formed in part being reflux to the second Rectification column and can be used as reflux to the third rectification column. A corresponding design has the advantage that a further increase in argon yield and total energy range can be achieved.

In the context of the present invention, bottom liquid, in particular, can be formed in the third rectification column, which liquid flows into the second

Rectification column can be fed. It can also be provided that part of this bottom liquid is used to cool an overhead condenser of an additionally present argon column (ie a "fourth" column as explained below) and only then feed it into the second rectification column. By contrast, a further part can be transferred directly into the second rectification column bypassing such a top condenser.

In particular, as mentioned, the third rectification column receives air previously released in a flash machine as a gaseous feed stream. In other words, in particular the previously compressed and cooled air can be fed to the third rectification column, which air is expanded by means of an expansion machine. It goes without saying that this is additional air which, in addition to the air fed into the first rectification column, is subjected to decomposition in the process or the system.

Approximately in the middle of the third rectification column, more generally in a region between the bottom and the top, a further liquid stream can optionally be removed from the third rectification column, which can be fed back into the first rectification column in particular by means of a pump.

As mentioned, oxygen-rich fluid is formed in the bottom of the second rectification column. This can be seen in the second rectification column. The

Removal can take place partly in gaseous and partly in liquid form. This fluid typically has an oxygen content of more than 97 mole percent, in particular more than 99.0 mole percent. From the head of the second

Rectification column can be removed further fluid that in a

Embodiment of the invention can be derived from the air separation plant and discarded. It is a nitrogen-oxygen mixture. In another embodiment of the present invention, the top gas is the second Rectification column, however, formed as a further nitrogen-rich fluid and provided as a further nitrogen-rich air product.

The top gas of the second rectification column can be obtained with a higher degree of purity by withdrawing a gaseous partial stream slightly below the top of the second rectification column. By withdrawing this partial stream, a nitrogen product with typically only about 1 ppm, maximum 100 ppm, of oxygen is generated in a conventional air separation plant at the top of the second rectification column.

This product can either be directly in the main heat exchanger

The temperature level at or near the ambient temperature is warmed up or partially warmed up and compressed in a hot compressor to a pressure level of, for example, approximately 1.7 to 2.5 bar, in particular approximately 2.2 bar. In the course of heating, this product, or a partial stream thereof, can also be removed from the skin heat exchanger at an intermediate temperature level, passed through a cold compressor and fed back to the main heat exchanger and further heated. The compression in the hot compressor can follow this. The cold compressor can in particular be coupled to an expansion machine which expands the compressed and partially cooled feed air which is fed into the third rectification column. In this context, a nitrogen-rich liquid reflux to the second rectification column can be used in particular.

In a corresponding embodiment, the invention is characterized in particular by the fact that nitrogen-rich overhead gas is formed at the top of the second rectification column, and that at least a portion of the nitrogen-rich overhead gas as a further nitrogen-rich air product with a residual oxygen content which is above the residual oxygen content of the overhead gas of the first rectification column, however, is still significantly below the residual oxygen content of fluids which are removed from these oxygen columns at the top in regular SPECTRA processes with oxygen columns. In the context of this embodiment of the present invention, this can also be made possible in particular by the fact that compared to conventional

Oxygen columns additional trays or packing areas in the second

Rectification column installed that removed another fluid below and that a liquid, nitrogen-rich reflux is added to the top of the second rectification column.

In the context of the present invention, the overhead gas of the first rectification column has a residual oxygen content of 0.1 ppb to 10 ppm, more particularly 0.5 ppb to 1 ppm or up to 100 ppb. The residual oxygen content of the at least one nitrogen-rich provided in the context of the present invention

Air product formed using this top gas is therefore in this range. The residual oxygen content of the top gas of the second rectification column is above this in the embodiment of the present invention just mentioned. This residual oxygen content is in particular 10 ppb to 100 ppm, in particular 100 ppb or 500 ppb to 10 ppm. The residual oxygen content of the further nitrogen-rich air product provided in the context of the present invention using this overhead gas is therefore in this range. All data in ppb or ppm indicate the molar fraction.

As mentioned, the residual oxygen content of the further nitrogen-rich air product obtained in the mentioned embodiment of the invention, which is provided using the top gas of the second rectification column, can be achieved in particular by equipping the second rectification column with additional trays or packing areas. In this embodiment of the present invention, the second rectification column therefore preferably has 50 to 120, for example 70 to 95, in particular 72 to 90, theoretical plates.

As also mentioned, the residual oxygen content of the further nitrogen-rich air product achieved in the mentioned embodiment of the invention can be found below

Use of the top gas of the second rectification column is provided, but in particular achieve the use of a nitrogen-rich liquid reflux to the second rectification column. The provision of a nitrogen-rich liquid stream and its function as reflux in an upper region of the second rectification column is therefore provided in the context of a particularly preferred embodiment of the present invention. The reflux has a residual oxygen content which is in particular lower than the residual oxygen content of the top gas of the second rectification column. The nitrogen-rich liquid stream which is used in this embodiment of the present invention to form the reflux to the second rectification column can in particular be removed from the first rectification column or from a further rectification column.

In particular for the supply of semiconductor plants (so-called Fabs), in addition to gaseous, high-purity nitrogen that is as free of particles as possible, oxygen is also increasingly being supplied with comparatively small amounts

gaseous argon desired. For this purpose, either liquid argon can be delivered or evaporated on site, or gaseous argon can be produced on site. The delivery of liquid argon not only brings economic disadvantages (transport costs, refueling losses, cold losses due to evaporation against ambient air), but also places high demands on the

Reliability of the logistics chain. For this reason, plants for the low-temperature separation of air are increasingly in demand, which, in addition to larger quantities of gaseous, high-purity nitrogen, can also supply smaller quantities of gaseous argon. The nitrogen produced should typically have only about 1 ppb, a maximum of 1000 ppb, oxygen, be essentially particle-free, and be able to be delivered at a significantly above-atmospheric pressure level.

Air separation plants are typically used to obtain argon

Double column systems and so-called raw and possibly so-called

Pure argon columns used. An example is illustrated by Häring (see above) in Figure 2.3A and described from page 26 in the section "Rectification in the Low-pressure, Crude and Pure Argon Column" and from page 29 in the section "Cryogenic Production of Pure Argon". As explained there, argon accumulates in corresponding plants at a certain height in the low-pressure column (so-called argon maximum). At this or another favorable point, possibly also below the argon maximum (at the so-called argon transition), gas enriched in argon with an argon concentration of typically 5 to 15 mol percent can be drawn off from the low-pressure column and transferred to the crude argon column. A corresponding gas typically contains about 0.05 to 100 ppm

Nitrogen and otherwise essentially oxygen. It is expressly emphasized that the values given for the gas drawn off from the low-pressure column are only typical example values. The crude argon column essentially serves to separate the oxygen from the gas drawn off from the low-pressure column. The oxygen separated off in the crude argon column or a corresponding oxygen-rich fluid can be returned in liquid form to the low-pressure column. The oxygen or that

Oxygen-rich fluid is typically fed into the low-pressure column several theoretical or practical trays below the feed point for liquid drawn off from the high-pressure column, oxygen-enriched and nitrogen-depleted and possibly at least partially evaporated. A gaseous fraction remaining in the crude argon column and essentially containing argon and nitrogen is separated further in the pure argon column to obtain pure argon. The crude and pure argon columns have top condensers, in particular with a portion of the withdrawn from the high-pressure column

Oxygen-enriched and nitrogen-depleted liquid can be cooled, which partially evaporates during this cooling. Other fluids can also be used for cooling.

In principle, a pure argon column can also be dispensed with in corresponding systems. In this case, the system is typically designed or operated in such a way that the nitrogen content at the argon transition is below 1 ppm or below the required product purity. However, this is not a mandatory requirement. Argon of the same quality as from a conventional one

In this case, pure argon column is typically made somewhat lower than that from the crude argon column or a comparable column

Fluid conventionally transferred into the pure argon column is withdrawn, the trays in the section between the crude argon condenser, that is to say the top condenser of the crude argon column, and a corresponding vent for an argon product, in particular serving as barrier plates for nitrogen.

Even if only comparatively small quantities of argon are in demand, a complete air separation plant with argon rectification (as explained above) has conventionally still to be installed for the production of the gaseous argon (ie equipped with a classic low-pressure column for oxygen production). The amount of air to be processed in such an air separation plant is determined by gaseous argon or gaseous nitrogen, ie one large amount of the gaseous oxygen falls as not or only poorly

usable residual gas. Furthermore, in conventional plants, it is not possible to generate nitrogen at a significantly above-atmospheric pressure level with large production quantities at the same time. The nitrogen is produced here as a low-pressure product. Known plants using the high pressure column for nitrogen production are typically not well suited for argon production.

In a particularly preferred embodiment, the present invention now proposes a method and an air separation plant, by means of which, in addition to larger quantities of high-purity, gaseous nitrogen at a clearly superatmospheric pressure level, comparatively smaller quantities of argon can also be advantageously provided.

In the context of the present invention, according to this particularly preferred embodiment, fluid is taken from the second rectification column to obtain argon and used as a third stream or to form a third stream, this fluid having a higher argon content than that of the oxygen-rich liquid bottoms in the sump the second rectification column is formed. This fluid also has a lower oxygen content than the oxygen-rich bottom liquid which is formed in the bottom of the second rectification column. In particular, it can have 45 to 60 mole percent oxygen, 40 to 55 mole percent argon and less than 1 mole percent nitrogen. The fluid which is removed from the second rectification column and used as the third stream or to form the third stream can be removed at the level of the so-called argon maximum, as occurs in known low-pressure columns of air separation plants.

In this embodiment, a fourth rectification column is used, into which the third stream is fed, an argon-rich fluid having a content of more than 95 mole percent argon being formed in the fourth rectification column, and in particular directly or after further purification as one

Argon product can be used.

A content of less than 1 ppm nitrogen in the third stream can be achieved in particular by the fact that above the argon transition in the A corresponding nitrogen separation takes place in the second column by means of suitable additional trays. If the fluid that is taken from the second rectification column and used to form the third stream, has one

correspondingly low nitrogen content, this can in particular without

Use of a classic pure argon column as the fourth product

Rectification column can be provided. If the nitrogen content is significantly higher, a pure argon column is typically used in addition to a corresponding fourth rectification column, which then corresponds to a classic crude argon column. As an alternative to using a pure argon column, liquid argon can also be somewhat below the top of the fourth rectification column

fluid conventionally transferred into the pure argon column are drawn off, so that argon of the same quality as from a conventional one

Pure argon column can be obtained.

In any case, the fourth rectification column is one

Rectification column, which largely corresponds to the typical crude argon column of a conventional process for the low-temperature separation of air. If necessary, a pure argon column can be provided. With the previously described low nitrogen contents, a pure argon column can typically be dispensed with. If the nitrogen content is higher than the 1 ppm mentioned, the oxygen and argon content can be correspondingly lower. Typically, the oxygen content here is 45 to 60 mole percent and the argon content is 40 to 55 mole percent, but in this case based on the

Non-nitrogen content of a corresponding fluid.

The third stream which is fed into the fourth rectification column can in particular also be a stream which is taken from a further rectification column, which in turn is fed with fluid from the second rectification column. Please refer to the explanations below. Even in this case, however, the fluid that comes from the second

Rectification column is removed, used to form the fourth stream, namely via the detour of the further rectification column.

The separation of argon can, as well as in part, as additional products within the scope of a corresponding embodiment of the present invention explained below, impure oxygen (with 90 to 98% mol percent

Oxygen content), technical oxygen (with 98 to 99.8% mol percent

Oxygen content) and high-purity oxygen (with traces of argon or

Hydrocarbons in the ppb range) are generated.

In principle, in the context of the present invention, an oxygen product can always be removed from the second rectification column, even if, for example, a third rectification column is provided for oxygen production. For example, an oxygen-rich gas can be removed from the second rectification column and (in contrast to the admixture to other streams, as illustrated for example in FIG. 31), separately by the

Main heat exchanger are guided and discharged from the system as a product. In this way, oxygen with a purity of 99% and better is obtained, which corresponds to the purity of so-called technical oxygen.

In the illustrated embodiment, a bottom liquid is formed in the bottom of the fourth rectification column, which in particular by means of a pump in the second

Rectification column can be recycled. A feed point in the second rectification column is in particular at the same height or in the vicinity of the removal point of the fluid which is used as the third stream or to form the third stream, with "near" here being one

Feed position is understood, which differs by no more than 10 theoretical or practical floors. Because the two flows from and to the fourth

Rectification column are in equilibrium, the feedback can also be at the same level, i.e. in particular on the same floor.

A particularly great advantage of the embodiment of the present invention that has just been explained is that by supplementing a SPECTRA process with an additional argon recovery, up to 50% of the argon contained in the process air can be obtained as a product without one

complex classic oxygen rectification is required. The problems explained above are therefore eliminated within the scope of the embodiment of the present invention which has just been explained. In the context of the present invention, in particular liquid argon can be obtained, which is a known one

Internal compression can be subjected. Also educated in the plant Pure oxygen can be subjected to internal compression, as is known from the specialist literature cited at the beginning.

According to a particularly preferred embodiment of the present invention, the second rectification column, as mentioned, is operated with a condenser evaporator arranged in its bottom region. To heat the

Condenser evaporators other streams than those mentioned can also be used. For example, part of the atmospheric air which was previously compressed and cooled can be used for this purpose in the context of the present invention. Corresponding air can be present, for example, at the pressure level of the first rectification column or can be expanded beforehand by means of an expansion machine. In the former case, the air is typically

Main condenser of the air separation plant to a temperature level close to its condensing temperature, i.e. a temperature level which is not more than 50 K, 25 K or 10 K above the condensing temperature is cooled. In the latter case, the air is only cooled to a temperature level before its relaxation, which is in particular below -50 ° C, but at least 50 K above that

Condensing temperature. In this case, the pressure is typically released to a pressure level which is below the first pressure level at which the first rectification column is operated, typically to about 4 to 6 bar absolute pressure. The air used to heat the condenser evaporator liquefies at least partially and can therefore be fed in an appropriate form into the first and / or the third rectification column, with any occurring

Differences in pressure can be compensated by the interposition of a pump or by a purely hydrostatic-geodetic pressure increase.

However, one or more further material flows can also be used to heat the condenser evaporator in the second rectification column.

In particular, this can be the fluid which contains oxygen, nitrogen and argon, which is taken from the first rectification column as the second stream or is used to form the second stream and which is transferred to the second rectification column, or a part thereof . A corresponding second liquid stream is removed, for example, from the first rectification column, passed through the condenser evaporator, supercooled and then in particular below a top region, ie in particular below the nitrogen-rich reflux, fed to the second rectification column. In this way, this second stream can be used as reflux to the second rectification column. The condenser evaporator can also be operated with overhead gas from the third rectification column, as mentioned.

In the context of the present invention, as mentioned, a nitrogen-rich reflux to the second rectification column can be formed from the first rectification column using nitrogen-rich liquid. A corresponding stream of material can be cooled in particular in the condenser evaporator of the second rectification column; however, it is also possible to use one

corresponding stream of material uncooled into the second rectification column

feed. In any case, this material stream is advantageously removed from the first rectification column significantly above the second material stream. The

Withdrawal typically takes place in the range of 20 theoretical or practical trays below the top area of the first rectification column.

In the context of the present invention, top gas is removed from the second rectification column and, in particular, is discharged from the air separation plant, as already explained above in various configurations. According to one embodiment of the present invention, at least some of this top gas is expanded, heated and removed from the

Air separation plant rejected.

In the context of the present invention, the second rectification column can, as mentioned, be operated at the second pressure level, in particular at a pressure level of 1.1 to 1.6 bar absolute pressure, with the first rectification column being supplied with compressed and cooled air, from which a partial flow is by means of an expansion machine is expanded to the second pressure level at which the second rectification column is operated. After its expansion in the condenser evaporator, which is arranged in the bottom region of the second rectification column, this partial stream can be at least partially liquefied and fed into the first rectification column. Such an embodiment has the advantage that both the argon yield and the total energy range are significantly improved. The relaxation machine used for this relaxation can be coupled to a compressor, which in the previously explained embodiment of the invention further air product, which is formed using overhead gas from the second rectification column, is hot compressed. In addition to or as an alternative to such a coupling, braking, for example by means of a generator and / or by means of an oil brake, can also be provided. By means of a comparable further

In an embodiment of the present invention, the expansion machine can also be expanded with additional fluid.

In general, the fourth can within the scope of the present invention

Rectification column, in the configurations in which it is present, are operated with a top condenser, the evaporation space on one

Pressure level of less than 1.2 bar absolute pressure or 150 mbar gauge pressure is operated and cooled with fluid, which is then fed into the second rectification column or discharged from the air separation plant. This fluid can in particular be the bottom liquid of the first or, if present, the third rectification column, or a corresponding fluid can comprise part of this bottom liquid (s). However, other fluids can also be used. Such an operating pressure level of the evaporation chamber of the

Head capacitor can increase the argon yield in the context of the invention. This can be made possible in particular by the fact that corresponding fluid is not used as regeneration gas in the air separation plant.

In particular, within the scope of the present invention or a corresponding configuration, fluid that is in the sump of a

Rectification column, in particular the first or the third rectification column, can be used in a proportion as the fluid or as a part of the fluid, by means of which the top condenser of the fourth rectification column is cooled. As mentioned, the corresponding fluid can then be obtained in particular from the

Air separation plant run or used in another way advantageous.

In the context of a corresponding embodiment of the present invention, overhead gas which is formed in the fourth rectification column can in particular have a content of more than 99.999 mol percent argon. In this embodiment, this overhead gas can be obtained as an argon product from the rectification without further rectification

Air separation plant to be run. As mentioned, arise accordingly high argon contents in particular when an extremely low-nitrogen fluid is removed from the second rectification column and into the fourth

Rectification column is transferred.

Alternatively, it is also possible to use a top gas in a corresponding way

Form in the fourth rectification column with a lower argon content, for example with an argon content of more than 95 and less than 99.999 mole percent. In this embodiment, a further rectification column in the form of a known pure argon column can then be provided, in which this overhead gas can then be rectified to obtain an argon product with a corresponding purity of more than 99.999 mol percent. With regard to known crude and pure argon columns, reference is made to the specialist literature cited at the beginning.

As also mentioned, however, instead of overhead gas, an argon-rich fluid in liquid form below the top of the third rectification column in the form of the fifth stream can also be withdrawn from this in place of overhead gas.

Within the scope of the present invention, as mentioned several times, an amount of the argon product formed in the air separation unit can comprise 1% to 50% of a total amount of argon supplied to the air separation unit in the form of atmospheric air.

According to a variant of the process according to the invention, a fifth rectification column can be used to produce ultra-high purity oxygen with an oxygen content of, for example, 99.5 mole percent with a residual content of up to 1 ppb methane, 10 ppb argon and not more than 1 ppb of other air components a liquid is formed with an oxygen content which is above an oxygen content of the oxygen-rich bottom liquid which is formed in the bottom of the second rectification column.

This fifth rectification column can in particular be designed as a double column which has an upper part and a lower part which are separated from one another in a fluid-tight manner. Anyway, in the upper part and the lower part of the

Double column each formed a top gas and a bottom liquid. The upper part can be used as a barrier against high boilers such as hydrocarbons are and is, from a functional point of view, an outsourced part of the fourth rectification column. The lower part, ie the fifth rectification column itself, is used as a stripping column for separating low boilers such as argon.

Overall, in the context of the present invention in the fifth

Rectification column or its lower part a liquid with a

Oxygen content are formed which is above an oxygen content of

oxygen-rich sump liquid that is in the sump of the second

Rectification column is formed, and the fifth rectification column can be used to form the third stream which is fed into the fourth rectification column using the fluid which is withdrawn from the second rectification column and has a higher argon content than the oxygen-rich bottom liquid of the second rectification column .

In the upper part of the fifth column just explained, designed as a double column, i.e. in the part that is functionally part of the second rectification column, at least part of the fluid removed from the second rectification column can be fed in, which is the fourth stream or the formation of the fourth stream is used.

The upper and the lower part of the double column just explained can each be operated with a reflux which is provided using bottom liquid from the fourth rectification column, if present, overhead gas from the upper and lower part of the double column just explained can be fed into the fourth rectification column , and the liquid with the

Oxygen content that is above the oxygen content of the oxygen-rich

Bottom liquid, which is formed in the bottom of the second rectification column, can be formed in the form of bottom liquid of the lower part.

In particular, the invention can include that the lower part of the double column, that is to say the fifth rectification column in the actual sense, by means of a

Condenser evaporator is heated in the fluid from the fourth

Rectification column is cooled. The present invention also extends to an air separation plant which is set up to carry out a method according to a previously explained embodiment in the present invention. Features and advantages of a

corresponding air separation plant is expressly referred to the corresponding independent claim and the above statements. In particular, such an air separation plant has means which are set up to carry out a method in accordance with one of the explained embodiments.

In a particularly preferred embodiment of the air separation plant proposed according to the invention, it has a main heat exchanger which is arranged in a first prefabricated cold box, and the first rectification column with the heat exchanger used for cooling its top gas is in a second

prefabricated coldbox arranged. The second and third rectification columns are arranged in a third prefabricated cold box in such an air separation plant.

Such an air separation plant can in particular have one or more further rectification columns, as explained above with reference to the fourth and fifth rectification columns. The one or at least one of the several further rectification columns can be in the third

prefabricated cold box or in one or more other prefabricated

Cold boxes can be arranged.

A cold box is an insulated container made of metal, which in each case surrounds all or all of the apparatus mentioned and is filled with insulating material, for example pearlite. Advantageously, in addition to the one or more devices mentioned, the devices required for operation, such as heat exchangers and / or fittings, are arranged in the cold box, so that only piping has to be carried out when creating a corresponding system. This facilitates the creation on site. A prefabrication includes, in particular, the creation of the cold box outer casing and, if necessary, the introduction of the above-mentioned apparatus with the corresponding piping. Therefore, only a connection (piping) has to be made on the construction site. The invention is explained in more detail below with reference to the accompanying drawings, in which preferred embodiments of the present invention are illustrated.

Brief description of the drawings

Figures 1 to 31 illustrate air separation plants and parts of

Air separation plants in total or partial representation.

Detailed description of the drawings

In the following figures, air separation plants are different

Embodiments of the present invention illustrated and designated 100 to 3100. The components of corresponding plants are first explained with reference to FIG. 1 and the air separation plant 100, which is not illustrated there, as illustrated. In the air separation plants 200 to 3100 according to FIGS. 2 to 31, elements which are structurally or functionally corresponding in each case are not repeatedly explained there.

1 shows an air separation plant 100 according to the invention in the form of a schematic plant diagram.

A feed air stream a is fed to the air separation plant 100 from a warm part of the air separation plant 100, which is illustrated schematically here with 110 and in particular comprises devices for purifying and compressing feed air. This feed air flow a is in a main heat exchanger 1

Air separation plant 100 cooled and removed from the main heat exchanger 1 near its cold end. The warm part 110 of the air separation plant can be designed in a manner customary in the art. For an example which does not restrict the present invention, reference is made to the explanations relating to FIG. 2.3A at Häring (see above).

The feed air stream a is then divided into two sub-streams b and c, the sub-stream b being fed directly into a first rectification column 11. The partial stream c, however, is passed through a condenser evaporator 121 of a second rectification column 12 and then, in particular after being combined with other streams as explained below, also fed into the first rectification column 11. The partial streams b and c are each fed into the first rectification column 11 at a suitable height.

In the first rectification column 11, which is operated at a previously explained "first" pressure level, a nitrogen-enriched or in the

Mainly nitrogen head gas and an oxygen-enriched bottom liquid formed. The first rectification column 11 is taken from two streams d and e, each comprising fluid which is enriched in oxygen compared to atmospheric air.

The stream d is first further cooled in the main heat exchanger 1 and then passed through a heat exchanger 2 which, as explained below, is used to cool overhead gas from the first rectification column 11. The material flow e is first treated in a manner comparable to the material flow d, a part of the material flow e being able to be branched off as material flow e1 before the rest of the material flow e, which for the sake of simplicity is also referred to as e, is fed to the heat exchanger 2. External liquid nitrogen X can also be fed to the material flow e if required. In the example shown, the stream e is taken from the bottom of the first rectification column 11, while the stream d is taken from one position, several theoretical or practical trays above the bottom of the first rectification column 11. The material flows d and e are passed separately through the heat exchanger 2.

The material stream e is then partially heated in the main heat exchanger 1 and expanded in the form of two partial streams by means of an expansion machine 3 and possibly a bypass valve, which is not specifically designated. Then these

Partial streams, combined with each other and with other material flows, in

Main heat exchanger 1 is heated and executed from the air separation plant in the form of a collecting stream f or in the warm part 1 10, for example for

Regeneration of absorbers used.

In contrast, the material flow d, if necessary after branching off and blowing off a partial flow into the atmosphere A, in a compressor 5 which is equipped with one of the ones shown here

Relaxation machine 3 is coupled, compressed, then cooled and comparable to stream c, returned to the first rectification column 11. As illustrated in the form of a dashed stream d1, a bypass can also take place here. The compressor 5 is coupled to the expansion machine 3 and also has an oil brake (not specifically designated here).

Top gas from the top of the first rectification column 11 is passed in the form of a stream g through the heat exchanger 2 and at least partially liquefied there. This partially liquefied overhead gas can partly be returned to the first rectification column 11 in the form of a reflux stream and to a further extent as

Liquid nitrogen product B can be provided. For this purpose, a part in one

Subcooler 6 subcooled and run as a correspondingly subcooled liquid nitrogen product B. A portion relaxed in the subcooler 6 for cooling can be combined with the material flow e already mentioned. Part of the material flow g can also be discharged as a so-called purge P. Additional head gas can be heated in the form of a material flow h in the main heat exchanger 1 and as a gaseous one

Nitrogen product C executed or used as sealing gas D. The gaseous nitrogen product C represents a “nitrogen-rich air product” previously explained in relation to different configurations of the invention.

In the example illustrated in FIG. 1, a material stream i is carried out in liquid form from the first rectification column 11, which subcooled in the condenser evaporator 121 of the second rectification column and as reflux to the second

Rectification column 12 is abandoned. From a region near the top of the first rectification column 11, at least clearly above the stream i, another, correspondingly nitrogen-rich, stream i1 is withdrawn in liquid form and above the stream i, in particular at the top, as a return to the second

Rectification column 12 abandoned.

A liquid can from the bottom of the second rectification column 12

oxygen-rich stream k are subtracted by means of a

Internal compression pump 7 or brought to pressure by means of pressure build-up evaporation and then heated in the main heat exchanger 1 and can be provided as an internally compressed oxygen pressure product E. A part of the material flow k can also be provided as a liquid oxygen product F. Further oxygen-rich liquid, but with a lower oxygen content, can analogously in the form of a Material stream k1 withdrawn from the second rectification column 12, brought to pressure by means of a further internal compression pump 7a and as another

internally compressed oxygen pressure product E1 are provided. A portion can optionally also be returned in the form of a material flow k2. A part can also be provided as liquid oxygen product F. From the head of the second

In the example shown, rectification column 12 is withdrawn from stream I, which, after being combined with another stream, likewise heats up and, in

illustrated example to which atmosphere A can be given. The streams i and H are subcooled in a subcooler 9 against the stream I before they are fed into the second rectification column 12.

From a central area of the second rectification column 12, in particular at the argon transition, a stream m is withdrawn, which is fed into a lower area of a rectification column 14, which is referred to as the fourth rectification column 14 for reasons of consistency (in the embodiment not illustrated according to the invention, this is according to the invention used third

Rectification column 13 not available). From the swamp of the fourth

Rectification column 14, a further stream n is withdrawn by means of a pump 8 and returned to the second rectification column 12. A material stream o is drawn off from the fourth rectification column 14 in an upper region, passed through a top condenser 141 of the fourth rectification column 141, at least partially liquefied there and returned to the fourth rectification column 14 as reflux. An unevaporated portion can be released into atmosphere A. A liquid argon product G becomes the fourth below the head

Rectification column 14 in the form of a stream p withdrawn liquid. A corresponding material flow p can also be at least partially pressurized by means of a pump and heated in the main heat exchanger 1, so that an internally compressed argon product can be provided in this way.

The top condenser 141 of the fourth rectification column 14 is cooled with liquid, which can be fed to the top condenser 141 in the form of the material flow q already mentioned. The material flow q can be formed using at least part of the material flow e1 also mentioned above and optionally the material flow k2. Portions not used to form stream q can be combined with stream c in the form of stream q1 and into the first Rectification column 1 1 are fed. A stream r can be drawn off from an evaporation chamber of the top condenser 141 of the fourth rectification column 14, which stream can preferably be heated in the main heat exchanger 1 and carried out from the system, preferably without back pressure or essentially back pressure after combination with the stream I as explained with regard to this stream I. In this way, a low pressure can be set in the evaporation space of the top condenser 141. Optionally, a portion r1 of the stream r can also be fed into the second rectification column 12. Liquid from the evaporation space of the top condenser 141 of the fourth rectification column 14 can, if necessary, be combined in the form of a stream s with the sub-streams of the stream e before they are heated in the main heat exchanger 1.

As already mentioned, the material flows i and / or i1 can be subcooled against the material flow I in subcoolers, each designated 9, against the material flow I. The same applies optionally to the material flow q compared to the material flow r. Several subcoolers 9 can also be in a common apparatus

be summarized.

FIG. 2 shows a further air separation plant which is not according to the invention in the form of a schematic plant diagram and is designated overall by 200.

In contrast to the air separation plant 100 illustrated in FIG. 1, a partial flow a1 of the feed airflow a is taken from the main heat exchanger 1 at an intermediate temperature level, relaxed by means of a relaxation machine 201, which is coupled to a generator, and otherwise used like the material flow c according to FIG. 1 . If a corresponding relaxation machine is available and is used for the same or comparable purpose, this is also designated with 201 in the following figures. The features which differ from the air separation plant 100 can be provided individually or together and / or can be combined with any features described above and below.

FIG. 3 shows a further air separation plant, which is not according to the invention, in the form of a schematic plant diagram and is designated overall by 300. As illustrated here, a material flow corresponding to material flow a1 in FIG. 2 can also be fed back to main heat exchanger 1 after it has expanded in expansion machine 201, where it can be heated and blown off to atmosphere A. With regard to further details, reference is expressly made to the explanations for the above figures. The features that differ from the preceding figures can also be provided individually or together and / or combined with any features described above and below.

A further air separation plant, not according to the invention, is illustrated in FIG. 4 in the form of a schematic plant diagram and is designated overall by 400.

In contrast to that illustrated in the previous figures

Air separation plants 100 to 300 do not use a material flow corresponding to material flow H here. With regard to further details, reference is expressly made to the explanations for the above figures. The features which differ from the preceding figures can also be provided individually or together and / or combined with any features described above and below.

FIG. 5 illustrates an air separation plant in accordance with an embodiment of the present invention in the form of a schematic plant diagram and is designated overall by 500.

The air separation plant 500 according to FIG. 5 differs from the previously explained configurations in particular in that the second

Rectification column 12 is formed as part of a double column which additionally has the third rectification column 13 already mentioned. A portion of the feed air stream a, as previously designated a1 and treated accordingly, is fed into a lower region of this third rectification column 13.

A material flow q2, which is otherwise used in a manner comparable to the material flow q of the preceding figures and is therefore also referred to here downstream as q, is

Bottom liquid of the third rectification column 13, the partial stream e2 and optionally of the material flow k2. Top gas from the third rectification column 13 is at least partially liquefied in the form of a stream u in the condenser evaporator 121 and then in the form of a stream u1 as a return to the third

Rectification column 13 and used in the form of a partial stream u2 as reflux to the second rectification column 12.

Nitrogen-rich liquid is withdrawn from the third rectification column 13 in the form of a stream v via a side draw and is conveyed into the first rectification column 11 by means of a pump 501.

With regard to further details, reference is expressly made to the explanations for the above figures. The features which differ from the preceding figures can also be provided individually or together and / or combined with any features described above and below.

A further air separation plant not according to the invention is illustrated in FIG. 6 in the form of a schematic plant diagram and is designated overall by 600. The representation in FIG. 6 and the subsequent figures differs slightly from those in FIGS. 1 to 5, although part of the function of the elements shown is identical or comparable with regard to the technical function and is therefore indicated with identical reference numerals.

The air separation plant 600 is also supplied with a feed air flow a from a warm part, which is also summarized here with 110

atmospheric air L is formed. In the warm part 1 10, a filter 1 11, through which feed air L is drawn in, a main air compressor 1 12 with aftercoolers, not specifically identified, a direct contact cooler, which is operated with water W, and an absorber set 1 15 are shown here. The feed air stream a is also cooled in a main heat exchanger 1 of the air separation plant 600 and removed from the main heat exchanger 1 near its cold end.

The feed air stream a is divided as before into two partial streams b and c, the partial stream b being fed directly into the first rectification column, also denoted here by 1 1. The second sub-stream c is in turn by a

Condenser evaporator 121 of a second one, also designated here as 12 Rectification column 12 performed, but here, as explained below, carried out from the air separation plant 600. In contrast to the condenser evaporator 121 illustrated in FIGS. 1 to 5, the flow of current in the condenser evaporator 121 according to FIG. 6 is not illustrated crosswise,

In the first rectification column 1 1, which is also operated here at the previously explained "first" pressure level, a nitrogen-enriched or in the

Mainly nitrogen head gas and an oxygen-enriched bottom liquid formed. From the first rectification column 11, two material flows d and e are also removed here, each comprising fluid which is enriched in oxygen in relation to atmospheric air.

The stream d is first further cooled in the main heat exchanger 1 and then passed through a heat exchanger 2 which, as explained below, is used to cool overhead gas from the first rectification column 11. The material flow e is first treated in a manner comparable to the material flow d, the material flow e here first being combined with the material flow c and then a further material flow q3 being branched off therefrom. Only then is this material flow, for the sake of simplicity further designated e, in the

Main heat exchanger 1 cooled further and fed to heat exchanger 2. The material flow q3 is referred to in the further course for comparison with the previous figures and because of its corresponding use with q.

As before, liquid nitrogen X can be fed to the stream e if required. In the example shown, stream e becomes the bottom of the first

Rectification column 1 1, the stream d, however, from one position several theoretical or practical trays above the bottom of the first

Rectification column 1 1 removed. The material flows d and e are passed separately through the heat exchanger 2.

The stream e is then partially heated in the main heat exchanger 1 and in the form of two streams by means of an expansion machine 3 and possibly one

Relaxation valve or relaxed via a bypass. These partial flows are then combined with one another and with further material flows in the

Main heat exchanger 1 is heated and from the air separation plant in the form of a Collective flow f executed or used in the warm part 1 10 of the air separation plant 600, for example for the regeneration of the absorbers of the adsorber set 1 14.

In contrast, the material flow d, if necessary after branching off and blowing off a partial flow into the atmosphere A, in a compressor 5 which is equipped with one of the ones shown here

Expansion machine 3 is coupled, compressed, then cooled and returned to the first rectification column. As illustrated in the form of a dashed stream d1, a bypass can also take place here. The compressor 5 is coupled to the expansion machine 3 and also has an oil brake (not specifically designated here). Any other combinations are also possible.

Top gas from the top of the first rectification column 11 is passed in the form of a stream g through the heat exchanger 2 and at least partially liquefied there. This partially liquefied overhead gas can partly be returned to the first rectification column in the form of a reflux stream and to a further extent as

Liquid nitrogen product B can be provided. For this purpose, a part in one

Subcooler 6 subcooled and run as a correspondingly subcooled liquid nitrogen product B. A portion relaxed in the subcooler 6 for cooling can be combined with the material flow e already mentioned. A part can also be rejected as a so-called Purge P. Additional head gas can be heated in the form of a material flow h in the main heat exchanger 1 and can be designed as a gaseous nitrogen product C or used as a sealing gas D.

In the example illustrated in FIG. 6, too, the first

Rectification column 1 1 a stream i liquid executed, which in

Condenser evaporator 121 of the second rectification column 120 is supercooled and can be fed into the second rectification column 12 as reflux.

A liquid can from the bottom of the second rectification column 12

deducted oxygen-rich stream k, which is fed here in liquid form in a tank system 101. A corresponding liquid oxygen-rich material flow, here designated k3, can be drawn off from the tank system 101 or another tank, and then heated in the main heat exchanger 1 and provided as a gaseous oxygen product U. The second rectification column 12 can in particular be designed and operated in such a way that by means of it an ultrahigh-purity oxygen product U with the previously explained specifications can be provided. This does not have to be the case with the second rectification columns 12 of the air separation plants 100 to 500.

Further oxygen-rich liquid can be drawn off analogously in the form of a material flow k1 from the second rectification column 12, brought to pressure by means of an internal compression pump 7a and made available as an internally compressed oxygen pressure product E1. In the example shown, a stream I is withdrawn from the top of the second rectification column 12, which also forms the one already mentioned here

Material flow f is used.

A material stream m is drawn off from a central region of the second rectification column 12, in particular at the argon transition, and is fed into a lower region of a fourth rectification column, also designated here as 14. A further stream n is withdrawn from the bottom of the fourth rectification column 14 as above by means of a pump 8 and returned to the second rectification column 12. Head gas rises from the top of the fourth rectification column 14 into a condensation chamber of a top condenser 141, where it is at least partially liquefied and returned to the fourth rectification column 14 as reflux. An unevaporated portion can be released into atmosphere A. A stream p is drawn off liquid below the top of the fourth rectification column 14. The material flow p is brought to pressure by means of a pump 7b and then heated in the main heat exchanger 1, so that an internally compressed argon product I can be provided in this way.

The top condenser 141 of the fourth rectification column 14 is also cooled here with liquid, which can be fed to the top condenser 141 in the form of the already mentioned stream q3, which is referred to as q below. From an evaporation space of the top condenser 141 of the fourth

Rectification column 14, a stream r can be withdrawn, which

preferably in the main heat exchanger 1 and out of the main heat exchanger 1, preferably free of counterpressure or essentially free of counterpressure after combination with the material flow I and the material flow s explained below

Air separation plant can be run. In this way, a low pressure can be set in the evaporation space of the top condenser 141. Liquid from the evaporation space of the top condenser 141 of the fourth rectification column 14 is drawn off here in the form of the stream s.

FIG. 7 shows an air separation plant in accordance with a further embodiment of the present invention in the form of a schematic plant diagram

illustrated and designated 700 in total.

In contrast to the air separation plant 600 illustrated in FIG. 6, a partial flow of the feed air flow a, which is denoted as a1 for the first time in FIG. 2, is removed from the main heat exchanger 1 at an intermediate temperature level and expanded by means of a relaxation machine denoted as 201 above.

The rest of the feed airflow a is at least partially in the first

Rectification column fed, wherein a cross connection a2 between the sub-stream a1 and the stream a is provided.

The air separation plant 700 illustrated in FIG. 7 is further distinguished by the fact that the second rectification column 12 is designed as part of a double column which additionally has a third rectification column 13. The relaxed portion of the feed air stream a designated a1 is fed into a lower region of this third rectification column 13.

A material flow, which is otherwise used in a manner comparable to the material flow q of the preceding figures and is therefore also referred to here as q, is the third in the air separation plant 700 using sump liquid

Rectification column 13 formed. Top gas from the third rectification column 13 is at least partially liquefied in the form of a stream u in the condenser evaporator 121 and then used in the form of a substream u1 as a return to the third rectification column 13 and in the form of a substream u2 as a return to the second rectification column 12.

Nitrogen-rich liquid is withdrawn from the third rectification column 13 in the form of a stream v via a side draw and is conveyed into the first rectification column 11 by means of a pump, which is designated as 501 above. Another stream k4 becomes gaseous from the second rectification column 12 deducted and combined with the streams I and r to a stream designated here with f1. The stream f1, like the stream f, is in the

Main heat exchanger 1 heated and used accordingly. In the example shown, the material flows q, i and u2 are subcooled against the material flow I in a common subcooler 9.

With regard to further details, reference is expressly made to the explanations relating to the above figures, in particular to FIGS. 5 and 6. The features which differ from the preceding figures can also be implemented individually or together.

FIG. 8 shows an air separation plant according to a further embodiment of the present invention in the form of a schematic plant diagram

illustrated and designated a total of 800.

The air separation plant 800 according to FIG. 8 differs from the air separation plants 100 to 700 shown and explained above in particular in that a fifth rectification column 15 is used, which is set up as a rectification column for providing high-purity oxygen.

Furthermore, in the air separation plant 800, the material flow i becomes the third

Rectification column 13 is fed in and a substance stream w is liquidly removed in a region of this feed and into the second rectification column 12

fed. The feed of the stream i into the second rectification column 12 thus takes place “via the detour” of the third rectification column 13. Furthermore, part of the bottom liquid from the third rectification column 13 is fed directly into the second rectification column 12 in the form of a stream q4. This is equivalent to bypassing the top condenser 141 of the fourth rectification column 14, which is only fed with the remainder.

A material flow m1 is removed from the second rectification column 12 and fed into an upper part 15a of the fifth rectification column 15, which is separated from a lower part 15b by a barrier plate 15c. Liquid separating out on the blocking floor 15c is in the form of a stream n1 into the second

Rectification column 12 returned. The material flows r and s already explained are fed back into the second rectification column 12. The upper part 15a of the fifth rectification column 15 is used in particular to discharge argon, which for the most part flows into the fourth via a stream m2

Rectification column 14 is transferred. The material flow m2 also includes top gas from the lower part 15b of the fifth rectification column 15. Bottom liquid from the fourth rectification column 14 is fed in the form of a material flow m2 to the top of the upper and lower parts 15a, 15b of the fifth rectification column 15.

The fifth rectification column 15 is provided with a condenser evaporator 151 which is operated with a nitrogen-rich gas which is taken from the third rectification column 13 in the form of a stream x in which

Condenser evaporator 151 at least partially liquefied, and in the third

Rectification column 13 is recycled.

The example shown here also becomes the bottom of the second

Rectification column 12 a stream k removed and transferred to a tank system 101. Subsequently, however, an internal compression takes place here by means of a pump 7c. Furthermore, ultra-pure oxygen in the form of a material flow k5 is taken from the fifth rectification column 5. This is transferred to a tank system 102, temporarily stored there, evaporated in the main heat exchanger and provided as an ultra-high-purity oxygen product U1. Also a temporary storage of the

Argon product in a tank system 103 is possible.

With regard to further details, reference is expressly made to the explanations relating to the above figures, in particular to FIGS. 5 to 7. The features which differ from the preceding figures can also be implemented individually or together.

Figures 9 to 28 illustrate a number of further variants of

Air separation plants according to embodiments of the invention and according to configurations not according to the invention. Although different designations are used here for certain material flows and apparatuses than in the previous figures, these can also correspond to one another. In FIG. 9, an air separation plant with an oxygen column next to the first rectification column 11, that is to say a second rectification column 12, but without further rectification columns, is illustrated and designated 900 in total as the basis of the explanations for the subsequent figures. The majority of the components illustrated in FIG. 9 have already been explained several times. As illustrated in FIG. 9, a further storage tank 104 can be used and the material flow I can be passed separately through the main heat exchanger 1.

An air separation plant is illustrated in FIG. 10 and designated 1000, which also represents a variant of the air separation plant 900 according to FIG. 9, which is also not according to the invention, and in which a material flow k6 is removed from the second rectification column 12 via an intermediate take-off and, if appropriate, after intermediate storage in a buffer tank 105 and Internal compression in an internal compression pump 7d and heating in the main heat exchanger 1 is carried out as a corresponding oxygen product U2.

FIG. 11 shows a further air separation plant which is not according to the invention

illustrated and designated 1100, which represents a further variant of the systems 900 and 1000 according to Figures 9 and 10. The air separation plant 1100 comprises a fourth rectification column 14, from which the material flow p, which has been explained several times, is taken in liquid form. Corresponding argon can be buffered in a buffer tank 103 and after internal compression in a

Internal compression pump 7b and heating in the main heat exchanger 1 are carried out as a corresponding argon product I.

As illustrated here with 1 101, a cross connection between the material flows f and I can be provided on the cold side of the main heat exchanger 1. These

Cross-connection can be activated in particular in the event of a failure of one or more rectification columns, in order not to have to shut down the air separation plant 1100 as a whole.

As illustrated by 1 102, in this embodiment, externally provided liquid nitrogen and a liquid, nitrogen-rich stream i1 from the first rectification column can furthermore be provided at the top of the second rectification column 12 be abandoned. The latter has a lower nitrogen content than the top gas of the second rectification column 12. An additional separation section in the second rectification column 12 is designated 1103.

A material stream k7 is removed from the second rectification column 12, combined with material stream I, and in the form of this for the sake of simplicity, further with I

designated material flow out or the warm part 1 10 supplied. In this way, the overall yield of gaseous, internally compressed argon (stream p or product I) can be increased. The material flow r is fed to the material flow I, whereas the material flow s is used to form the material flow f.

In Figure 12 is another air separation plant not according to the invention

illustrated and designated 1200, which is in particular a variant of

Air separation plant 1 100 according to Figure 11. The air separation plant 1200 has the further expansion machine 201. The partial stream a1 is expanded in this further expansion machine 201 and used as explained several times.

The rest of the material flow a, which is not relaxed in the expansion machine 201, is treated in a manner comparable to the material flow, is treated in a manner comparable to the material flow b explained above and is therefore designated accordingly. A subcooler 9, which has already been explained several times, is also shown here. The second rectification column 12 is arranged with its lowest point in particular more than 6 m above the lowest point of the first rectification column 11.

An air separation plant is illustrated in FIG. 13 and designated 1300, which in particular shows a variant of the air separation plant 1200 according to FIG

Contrary to this, however, represents an embodiment of the present invention.

The air separation plant 1200 has the third, which has been explained several times

Rectification column 13 and the fifth rectification column 15, which have already been explained in more detail in relation to FIG. Reference is therefore expressly made to the explanations regarding air separation plant 800 according to FIG. 8 also with regard to plant 900.

In contrast to the air separation plant 800 according to FIG. 8, external liquid nitrogen X is in particular fed into the second rectification column 12 and a partial flow of the material flow r is combined with the material flow I and the material flow k3. This is particularly the case because in the second

Rectification column 12 there is no need for complete reflux or there is an optimum in this regard. As illustrated, the stream i is supercooled in the condenser evaporator 121 before it is fed into the second rectification column 12.

An air separation plant is illustrated in FIG. 14 and designated 1400, which in particular represents a variant of the air separation plant 1300 according to FIG. 13 according to the invention. The air separation plant 1400 is set up to provide a further pressure nitrogen product D1.

For this purpose, the top stream of the second rectification column 12 is obtained with a higher purity than the stream I previously. This is therefore designated 11 here. This is achieved by a further material flow I2 from the second one below the head

Rectification column 12 is withdrawn. Furthermore, the second rectification column here is provided with a further separation section 12a. The illustrated

Design also has a positive effect on argon yield and purity.

The material flows combined in the air separation plant 1300 according to FIG. 13 with the material flow I are now combined with the material flow I2 to form a material flow again designated I for the sake of simplicity. After heating in the main heat exchanger 1, the material flow 11 is partially compressed in an external compressor 1401. Another part reaches the warm part 110. Further details on this are also illustrated in more detail in FIGS. 27 and 28.

An air separation plant is illustrated in FIG. 15 and designated overall by 1500, which in particular is a variant of the invention

Air separation plant 1400 according to Figure 14 represents.

The bottom liquid of the third rectification column 13 used in the air separation plant 1400 according to FIG. 14 only for the formation of the material flow q becomes partially here to form a material flow q4 (see also here

Air separation plant 800 used according to Figure 8), the second Rectification column 12 is abandoned. The second rectification column 12 and the feed point of stream i are adjusted accordingly.

An air separation plant is illustrated in FIG. 16 and designated 1600, which represents a variant of the air separation plant 1500 according to FIG.

The material flow x formed in the previously explained plants 800 and 1300 to 1500 is not used here correspondingly. Instead, a material flow xl is considered

Branch stream of the top gas withdrawn from the third rectification column 13 is branched off and partially liquefied, as previously the stream x, in the condenser evaporator 151 and returned to the third rectification column 13 as reflux. Another part is heated in the form of a material flow x2 and at least partly executed as a further nitrogen product D2 from the air separation plant 1600.

An air separation plant is illustrated in FIG. 17 and designated 1700, which represents, in particular, a variant of the plants according to the previous figures, in which a fifth rectification column 15 is used. However, this is present here in a modified form and as previously designated 15a.

The rectification column 15a corresponds to the upper part 15a of the fifth

Rectification column 15 of the previous figures. A material flow m3 is transferred from its head into the fourth rectification column 14 and is fed into an area above the sump, which corresponds functionally to the lower part 15b of the fifth rectification column 15 of the previous figures, and which is therefore referred to here as 15b '. Liquid obtained here is transferred to the rectification column 15a in the form of a stream n3 by means of a pump (not designated separately)

pumped back. The configuration according to FIG. 17 can in particular

Non-ferrous metals can be achieved in the oxygen product U, because this arrangement does not allow the fluid that is led to the sub-column 15b 'to come into contact with a pump impeller, which is usually made of bronze.

In FIGS. 18 and 19, variants of systems are illustrated and designated 1800 and 1900, in which the warm part 110 and the flow of material through the main heat exchanger 1 are essentially modified. Only this warm part 110 and a section of the main heat exchanger 1 and material flows required for understanding this variant are shown in FIGS. 18 and 19.

The compressed, cooled and cleaned air in the main air compressor 112 is divided according to FIG. 18 into partial streams a2 and a3, of which the partial stream a2 is led from the warm to the cold end through the main heat exchanger 1. The

Material flow a3, on the other hand, is further compressed by means of a compressor or a compressor stage 112a, which is coupled to the main air compressor 112, and is then treated like material flow a from the previous figures. In particular, a partial flow, referred to here as a1 above, is expanded in the expansion machine 201 and then combined with the material flow a2. As illustrated in the variant according to FIG. 19, a relaxation machine 201 and the formation of the material flow a1 can also be dispensed with.

By using the measures illustrated in FIGS. 18 and 19, the energy consumption can be reduced since not all of the air has to be brought to a high pressure, but only the proportion of the material flow a3.

A variant of an air separation plant according to the invention is illustrated in FIG. 20 and designated by 2000, which has similarities with the

Air separation plant 800 according to FIG. 8 and other plants described above, in particular with regard to the treatment of material flows i and w. As a result, the third rectification column 13 can be used to split the stream i and a higher proportion of nitrogen product can be obtained. Reference is made to the above explanations and only a few material flows are referred to individually here and below.

The configuration according to FIG. 20 (and according to FIG. 8) has the particular advantage that the condenser evaporator 121 can be simplified and a likewise simplified regulation can be used. The stream w can in particular be regulated like a conventional Joule-Thomson stream.

In a variant of this according to the invention, which is shown in FIG. 21 and is designated 2100, the fourth is used using sump liquid

Rectification column 14 a stream q5 formed by means of a pump 7e through the modified heat exchanger 2, which is designated here by 2a, and thereby cooled and then returned to the third rectification column 13.

In this way, in particular the production of nitrogen in the third

Rectification column 13 can be improved, which allows higher expansions of all products.

In a further variant according to the invention, which is shown in FIG. 22 and designated 2200, a stream k5 formed by bottom liquid of the fifth rectification column 15 is treated accordingly and into the fifth

Rectification column 15 returned.

An air separation plant according to a further embodiment of the invention is illustrated in FIG. 23 and designated 2300. This differs from the configurations shown above in particular by a condenser evaporator 131 arranged in the bottom of the third rectification column 13. Functionally, this can be viewed as dividing the condenser evaporator in the second rectification column 12, which is designated here by 121a. In this way, the production of nitrogen in the second rectification column 12 or the third rectification column 13 can be improved.

As shown here, fluid in the form of a stream i2 can be removed from the second rectification column 2 via a side draw, passed through the condenser evaporator 141, at least partially liquefied, and fed into the third rectification column 13. At the same level, liquid can be removed from the third rectification column 13 and returned to the second rectification column 12 by means of a pump 7r.

A variant not according to the invention is shown in FIG. 24 using the 2400

designated plant, which lacks the third rectification column 13 or whose function is integrated into the first rectification column 11. The material stream i2 is partially heated here in the main heat exchanger 1, expanded in a relaxation machine 201a, cooled again in the skin heat exchanger 1 and passed to a portion through the condenser evaporator 121 of the second rectification column, at least partially liquefied, and again in portions to the first and second Rectification column 1 1, 12 abandoned. The relaxation machine 201 a is coupled to a generator, for example.

FIG. 25 illustrates an air separation plant according to the invention in accordance with a further embodiment of the present invention and is designated overall by 2500. This differs from the previous plants, in which a material flow a1 is formed and expanded, by the further treatment of this material flow a1.

The partial flow a1 is divided in the air separation plant 2500 into partial flows a4 and a5, the proportions of which can be set in each case via valves which are not specifically identified. The partial flow a4 is instead of the partial flow e, as is the case previously, in the expansion machine 3 and possibly the parallel one

Relaxation valve relaxed and thus partially used to drive the compressor 5. The partial stream a5, like the entire partial stream a1 previously, is fed, for example, into the third rectification column 13. The stream e is nevertheless formed and partially treated as before, but not by means of

Relaxation machine 3 and the relaxation valve 4 relaxed. It is fed into the third rectification column 13 below the stream a5. The third rectification column 13 can be provided with an additional separation section 13a.

The measures illustrated in FIG

Rectification columns 11 to 15 are thermally coupled. Residual gas from the first rectification column 1 1 can be used for the production of argon, oxygen and nitrogen. All or part of the stream e can be conducted to the second rectification column 12. The rest can be released via the expansion machine 3 as residual gas for use in the warm part 110.

An air separation plant according to a further embodiment of the present invention is illustrated in FIG. 26 and designated mi5 2600 in total. This represents in particular a variant of the air separation plant 2500. The partial stream a1 is also divided here into partial streams a4 and a5, but the material stream a4 is fed here to the material stream I before it is heated and discharged or fed to the warm part 110. The partial flow a5 is in the second Rectification column 12 fed. The function of the expansion turbine 201 therefore corresponds to that of a Lachmann turbine. The rectification columns 11 to 15 can be thermally coupled by the measures illustrated.

The partial flow d is formed and compressed as before, a compressor used for this purpose, which is therefore designated 5a differently, but is here driven purely by a motor. The partial stream e is fed into the fourth rectification column 14, as explained above in relation to FIG. 25.

In part illustrated in Figures 27 and 28

Air separation plants 2700 and 2800 according to embodiments of the invention, the material flow 11 mentioned for the first time in FIG. 14 is formed. To those there

Explanations are expressly referred to. As in Figure 28 using the

Air separation plant 2800 illustrates, the material flow 11 can first be partially heated in the main heat exchanger 1, in a compressor 201 b, which with the

Relaxation machine 201 is coupled, compressed, then on a

The intermediate temperature level is again fed to the main heat exchanger 1, heated further, and then fed to the compressor 1401.

As illustrated in part in FIG. 29, in an air separation plant 2900 according to one embodiment of the invention, the nitrogen of the material stream h can also be compressed accordingly, as previously illustrated with reference to FIGS. 28 and 29. The use of the compressor designated 140T here is optional.

FIG. 30 illustrates an air separation plant 3000 in the form of a schematic plant diagram according to an embodiment not according to the invention.

The air separation plant 3000 according to FIG. 30 has great similarities with the air separation plant 100 illustrated in FIG. 1, which is likewise not according to the invention. Only differences are explained below.

After it has been passed through the condenser evaporator 121 of the second rectification column 12, the partial stream c is not combined with further streams of material before it is fed into the first rectification column 11. Furthermore, no part of the material flow e as in FIG. 1 or the air separation plant 100 of the Stream e1 branched off, so that here the entire stream e is fed to the heat exchanger 2. The relaxation of the material flow e takes place here in the form of two partial flows in two expansion machines 3 and 4. The expansion machine 4 is coupled to a generator.

As illustrated here, the material stream j, which is designated differently here, is discharged from the second rectification column above the material stream i and, in particular, is fed to the second rectification column 2 at the top. From the top of the second rectification column 12, the stream I is withdrawn, which is heated without being combined with another stream, and especially after

Compression in a compressor 3001, as a further gaseous nitrogen product H from the air separation plant 100 can be executed. The gaseous

Nitrogen product H represents the previously different configurations of the

Invention explained "further nitrogen-rich air product".

As indicated here in a highly simplified manner, the main heat exchanger 1 can be arranged in a first prefabricated cold box 3010 in the air separation plant 3000. The first rectification column 11 with the heat exchanger 2 used to cool its top gas can be arranged in a second prefabricated cold box 3020. The second rectification column can be arranged in a third prefabricated cold box 3030. In contrast to the greatly simplified illustration in FIG. 1, these completely surround the elements mentioned.

FIG. 31 shows a variant of the air separation plant 3000 according to FIG. 31, which, however, represents an embodiment of the present invention and is designated 3100 overall. In contrast to the plant 3000 illustrated in FIG. 30, a partial stream a1 of the feed air stream is here additionally provided the third rectification column 13 mentioned several times and furthermore an argon recovery is provided in a fourth rectification column 14. Furthermore, a fifth rectification column 15 is provided in the air separation plant 3100. The terms "first", "second", "third", "fourth" and "fifth" rectification column are used consistently with the information given above, so that reference can be made to them. The formation and treatment of the material flows d, e, f, g, h, i, k and I takes place in the

Essentially as already explained for systems 100 and 3000 according to FIGS. 1 and 30, whereby in system 3100 again only one relaxation machine 4 instead of

Relaxation machines 3 and 4 is illustrated and the stream i is not fed directly into the second rectification column 12, but previously by the

Condenser evaporator 121 and a supercooling counterflow 202 is guided. Furthermore, the material flow k in the example illustrated here can be in a tank system

203 can be cached. The material flow I is also by the

Hypothermia counterflow 202 performed.

A material flow corresponding to material flow j in accordance with Appendix 100 is not formed here. Instead, a liquid reflux n to the second rectification column 12 is formed by taking top gas in the form of a stream m from the fourth rectification column and liquefying it in the condenser evaporator 121.

A part of the liquefied overhead gas is passed through the supercooling counterflow 202 and used in the form of the stream n, a further part, not designated, is returned to the first rectification column 11 as reflux. Additional liquid can be provided in the form of liquid nitrogen X. The third rectification column 13 in the plant 200 becomes a stream o by means of a pump

204 returned to the first rectification column 1.

The fifth rectification column 15 also represents a double column, for the function of which reference is made to the above explanations. The lower part 15b is operated with a condenser evaporator 151 which is heated using a stream p which is removed from the third rectification column 13 and then, i.e. downstream of the condenser evaporator 151, is returned to the third rectification column 13. Furthermore, ultrahigh-purity oxygen in the form of a material flow q is removed in the lower part 15b. This is transferred to a tank system 205, temporarily stored there, evaporated in the main heat exchanger 1 and made available as an ultra-high-purity oxygen product U.

A stream r is taken from the second rectification column 12 in the region of the argon transition or below and into the upper part 15a of the fifth

Rectification column 15, which is separated from the lower part 15a by a barrier plate 15c. Liquid separating out on the blocking floor 15c is returned below the stream r into the second rectification column 12. Top gas of the upper part 15a and the lower part 15b of the fifth

Rectification column 15 is via a stream s in the fourth

Rectification column 14 transferred. Bottom liquid of the fourth rectification column 14 is fed in the form of a stream t to the top of the lower part 15a and the upper part 15b of the fifth rectification column 15.

A top condenser 141 of the third rectification column 13 is cooled using bottom liquid of the second rectification column 12 in the form of a stream u which is previously passed through the supercooling counterflow 202.

Liquid from an evaporation chamber of the top condenser 141 is returned to the second rectification column 12 in the form of a stream v. Gas from an evaporation chamber of the top condenser 141 is drawn off in the form of a stream w and partly expanded into the second rectification column 12 and partly used to form a residual gas stream x, which also comprises fluid which is taken from the second and third rectification columns 12, 13.

Below the top, 14 argon-rich liquid in the form of a stream x is removed from the fourth rectification column. This can be stored in a tank system 206 before it is subjected to internal compression by means of a pump 207, heated, and can be made available as an argon product V.

Uncondensed overhead gas from the fourth rectification column 14 can be released into the atmosphere A in the form of a stream y.

The air separation plant 3100 according to FIG

Main heat exchanger 1 may be arranged in a first prefabricated cold box 31 10. The first rectification column 11 with the heat exchanger 2 used to cool its top gas can be arranged in a second prefabricated cold box 3120. The second rectification column 12 can together with the third

Rectification column 13 can be arranged in a third prefabricated cold box 3130. The third cold box 3130 in the illustrated example also contains the fifth

Rectification column 15 arranged. In the example shown, the fourth is

Rectification column 14 is arranged in a further prefabricated cold box 3140, in which, however, the fifth rectification column 15 is also arranged, for example can. However, the fourth rectification column 14 can also be arranged in the third cold box 3130. Any distribution is possible.

It should be emphasized again that, although measures according to individual embodiments of the invention are described in each case as part of corresponding systems in the above figures, these can also be used individually or in other systems without departing from the scope of the present invention. For example, in all cases, a motor and / or a

Turbine operation of a compressor can be provided and / or expansion machines can be braked by a generator and / or by means of braking and / or by coupling to a compressor.

Although certain air separation plants are described above as variants of plants explained further above, it goes without saying that the measures or features proposed here in each case can also be used in plants other than those described as the underlying.

Claims

Claims 1. A method for the low-temperature separation of air, in which a  Air separation plant (100-3100) with a first rectification column (1 1) and a second rectification column (12) is used, wherein - The first rectification column (1 1) is operated at a first pressure level and the second rectification column (12) at a second pressure level below the first pressure level, - From the first rectification column (1 1) fluid opposite  atmospheric air is enriched with oxygen, is taken in the form of one or more first material flows, at least a portion of the fluid that was removed from the first rectification column (11) in the form of the one or more first material flows is heated in a heat exchanger (2), - A portion of the fluid that has been heated in the heat exchanger (2) is compressed using a compressor (5) and into the first  Rectification column (11) is returned, - Head gas of the first rectification column (1 1) is condensed to a first portion in the heat exchanger (2) and to a second portion in the form of at least one nitrogen-rich air product from the  Air separation plant (100, 3100) is rejected, - From the first rectification column (1 1) further fluid, which contains oxygen, nitrogen and argon, is removed and used as a second stream or to form a second stream which is transferred to the second rectification column (12), and in the bottom of the an oxygen-rich bottom liquid is formed in the second rectification column (12) and at least some of it is discharged in the form of a third stream of material from the air separation plant (100, 200), characterized in that - A third rectification column (14) is used, the second  Rectification column (12) and the third rectification column (14) are designed as parts of a double column, the third rectification column (14) is arranged below the second rectification column (12), and the third rectification column (14) is fed with air. 2. The method of claim 1, wherein the air with which the third  Rectification column (14) is fed, comprises compressed and cooled air, which is expanded using a flash machine (201). 3. The method according to claim 2, wherein the second rectification column (12) is operated with a condenser evaporator (121) which is arranged in a bottom region of the second rectification column (12) and which uses fluid that the third rectification column (14) is removed and / or fed, is heated. 4. The method of claim 3, wherein the air with which the third  Rectification column (14) is fed, in the condenser evaporator (121), which is arranged in the bottom region of the second rectification column (12), at least partially liquefied and returned to the third rectification column (14) as a liquid reflux. 5. The method according to any one of claims 3 or 4, in which in the third  Rectification column (14) a top gas is formed, which is at least partially in the condenser evaporator (121), the bottom of the second  Rectification column (12) is arranged, liquefied and returned as reflux to the second and / or third rectification column (12, 14). 6. The method according to any one of claims 3 or 4, in which in the third Rectification column (14), a bottom liquid is formed, which is fed at least partially into the second rectification column (12). 7. The method according to any one of the preceding claims, wherein in the second rectification column (12) a nitrogen-rich overhead gas is formed and at least a portion thereof as a further nitrogen-rich air product from the  Air separation plant (3000, 3100) is discharged, one  Residual oxygen content of the top gas of the first rectification column (11) 1 ppb to 10 ppm and a residual oxygen content of the top gas of the second rectification column (12) is 10 ppb to 100 ppm. 8. The method according to claim 7, wherein the second rectification column (12) is equipped with 50 to 120 theoretical plates and / or a nitrogen-rich liquid stream is provided and fed as a return in an upper region of the second rectification column (12) 9. The method according to any one of the preceding claims, in which - From the second rectification column (12) fluid which has a higher  Argon content as the oxygen-rich bottom liquid of the second  Rectification column (12), removed and used as a third stream or to form a third stream, - A fourth rectification column (13) is used, in which the third  Material stream is fed in, an argon-rich fluid having a content of more than 95 being formed in the fourth rectification column (13)  Mole percent argon. 10. The method according to claim 9, wherein a fifth rectification column (15)  is used in which a liquid is formed with an oxygen content which is above an oxygen content of the oxygen-rich bottom liquid which is formed in the bottom of the second rectification column (12), and in which the fifth rectification column (15) to form the third stream under  Use of the fluid that is taken from the second rectification column (12) and a higher argon content than the oxygen-rich Has bottom liquid of the second rectification column (12) is used. 11. The method of claim 9 or 10, wherein an amount of in  Air separation plant (100-3100) formed argon product comprises 1 to 85 percent of a total, in the form of air of the air separation plant (100-3100) total amount of argon supplied. 12. Air separation plant (100-3100) with a first rectification column (11) and a second rectification column (12), which is set up - To operate the first rectification column (1 1) at a first pressure level and the second rectification column (12) at a second pressure level below the first pressure level, - From the first rectification column (1 1) fluid opposite  atmospheric air is enriched with oxygen in the form of one or more first material flows, - to heat at least a portion of the fluid that was taken from the first rectification column (11) in the form of the one or more first material flows in a heat exchanger (2), - Compress a portion of the fluid that has been heated in the heat exchanger (2) using a compressor (5) and into the first  Return rectification column (11), - Condensate overhead gas from the first rectification column (1 1) to a first portion in the heat exchanger (2) and to a second portion in the form of at least one nitrogen-rich air product from the  Air separation plant (100, 3100), - From the first rectification column (1 1) to remove further fluid, which contains oxygen, nitrogen and argon, and to use it as a second stream or to form a second stream which is transferred to the second rectification column (12), and - In the bottom of the second rectification column (12) to form an oxygen-rich bottom liquid and to discharge at least some of it in the form of a third stream of material from the air separation plant (100, 200), characterized in that - A third rectification column (14) is provided, the second  Rectification column (12) and the third rectification column (14) are designed as parts of a double column and the third rectification column (14) is arranged below the second rectification column (12), the Air separation plant (100-3100) is set up the third  Rectification column (14) to feed with air. 13. Air separation plant (100-3100) according to claim 12, which is set up to carry out a method according to any one of claims 1 to 1 1.