EP3559576A2

EP3559576A2 - Cryogenic air separation method, and air separation plant

Info

Publication number: EP3559576A2
Application number: EP17844599.5A
Authority: EP
Inventors: Stefan Lochner
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2016-12-23
Filing date: 2017-12-20
Publication date: 2019-10-30
Also published as: WO2018114052A2; WO2018114052A9; WO2018114052A3

Abstract

The present invention relates to a method for cryogenic air separation using an air separation plant (100) with a distillation column system (10) that comprises a high-pressure column (111) operated at a first pressure level, and a low-pressure column (112) operated at a second pressure level below the first pressure level. According to the invention, air in the air separation plant (100) is used to form one or more gaseous material flows which are subjected to isenthalpic expansion which is carried out starting from the first pressure level or a pressure level that differs from the first pressure level by not more than 1 bar, and through which a pressure difference of 3 to 6 bar is surmounted. The one or more gaseous material flows that is/are subjected to the gaseous expansion comprise a fluid amount of more than 500 standard cubic meters per hour, and the one or more gaseous material flows that is/are subjected to the gaseous expansion have an argon content of not more than 1 mole percent. The invention further relates to an air separation plant (100).

Description

description

Process for the low temperature decomposition of air and air separation plants

The invention relates to a method for the cryogenic separation of air and an air separation plant according to the preambles of the independent claims.

State of the art

The production of air products in the liquid or gaseous state by cryogenic separation of air in air separation plants is known and, for example, H.-W. Häring (ed.), Industrial Gas Processing, Wiley-VCH, 2006, especially Section 2.2.5, "Cryogenic Rectification".

Air separation plants have distillation column systems which can be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three-column or multi-column systems. In addition to the

Distillation columns for the recovery of nitrogen and / or oxygen in the liquid and / or gaseous state, ie the distillation columns for nitrogen-oxygen separation, distillation columns for obtaining further air components, in particular the noble gases krypton, xenon and / or argon, can be provided.

The distillation columns of said distillation column systems 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 pressure level of the high pressure column is for example 4 to 6 bar, in particular about 5 bar. The low-pressure column is at a pressure level of, for example, 1, 3 to 1, 7 bar, in particular about 1, 5 bar operated. In certain cases, such as Integrated Gasification Combined Cycle (IGCC) combined gasification processes, pressures of 3 to 4 bar can also be used in the low pressure column. The pressures given here and below are absolute pressures at the top of said columns. From EP 0 955 509 A1 a method and a device for air separation are known, which serve for the production of high-purity oxygen. An oxygen-containing liquid fraction is taken from at least one theoretical or practical bottom above the sump of the high pressure column and in the

Low pressure column fed. Gaseous nitrogen from the low pressure column is at least partially condensed in a top condenser by indirect heat exchange with a vaporizing liquid. At least a portion of the bottom liquid of the high pressure column is passed into the evaporation space of the top condenser of the low pressure column. From the lower part of the low-pressure column, a high-purity oxygen product is taken.

DE 25 26 350 A1 discloses a method for air separation with recovery of liquid oxygen and / or nitrogen by the so-called Mehtfachexpansions- method in an air separation plant with a high-pressure column, wherein a task-working pressure of the air to be processed against an operating pressure of

High pressure column is increased by several atmospheres.

A method described in EP 1 357 342 A1 and a corresponding device are used for air separation of air in a distillation column system for nitrogen-oxygen separation, which comprises a high-pressure column, a low-pressure column and a medium-pressure column and a crude argon column. At least one

Feed air stream is fed to the distillation column system. Of the

Low pressure column is removed at least one oxygen or nitrogen product stream. At least one first argon-enriched stream becomes the

Removed distillation column system and fed to the crude argon column. Of the

Rohargonsäule is taken from an argon-rich fraction whose argon content is greater than that of the first argon-enriched stream. The first argon-enriched stream is taken from the medium-pressure column. According to a method disclosed in EP 0 605 262 A1, a double column is used, the low-pressure column of which is operated at a pressure which is significantly above atmospheric pressure, in particular of the order of 2 to 5 bar. The high pressure column operated at a corresponding pressure,

especially in the order of 8 to 16 bar. Gaseous oxygen is taken directly from a lower area of the low-pressure column and the apparatus is at least partially kept cold by free expansion of at least one gaseous product leaving the low pressure column.

EP 2 801 777 A1 relates to an air separation plant with a

A distillation column system comprising at least one high pressure column and a

Low pressure column includes and a corresponding method. A

Main compressor unit is adapted to a total amount of air that the

Air separation plant is supplied in total, to compress to a pressure which is at least 4 bar higher than an operating pressure for which the high-pressure column is established. The main compressor unit has a slip-ring rotor motor.

The present invention has the particular object of making the creation of air separation plant easier. Disclosure of the invention

Against this background, the present invention proposes a method for

Cryogenic separation of air and an air separation plant with the features of the respective independent claims before. Embodiments are each the subject of the dependent claims and the following description.

Before explaining the features and advantages of the present invention, some principles of the present invention will be further understood and terms used below defined.

The devices used in an air separation plant are described in the cited literature, for example in Haring in Section 2.2.5.6, "Apparatus". Insofar as the following definitions do not deviate from this, reference is expressly made to the cited technical literature for language use, which is used in the context of the present application.

Fluids and gases may be rich or poor in one or more components as used herein, with "rich" being for a content of at least 50%, 75%, 90%, 95%, 99%, 99.5%, 99, 9% or 99.99% and "poor" for a content not exceeding 50%, 25%, 10%, 5%, 1%, 0.1% or 0.01% by mol, Weight or volume can stand. The term "predominantly" can correspond to the definition of "rich". Liquids and gases may also be enriched or depleted in one or more components, which terms refer to a content in a source liquid or gas from which the liquid or gas was recovered. The liquid or gas is "enriched" if it or this is at least 1, 1, 5, 1, 5, 2, 5, 10, 100 or 1, 000 times, and "depleted" if this or this is 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 the starting gas contains. As used herein, for example, "oxygen" or "nitrogen", it is understood to mean a liquid or gas that is rich in oxygen or nitrogen but need not necessarily consist exclusively thereof. The present application uses the terms "pressure level" and "temperature level" to characterize pressures and temperatures, thereby indicating that corresponding pressures and temperatures in a given plant need not be used in the form of exact pressure or temperature values to realize the innovative concept. However, such pressures and temperatures typically range in certain ranges, such as ± 1%, 5%, or 10% around an average.

Corresponding pressure levels and temperature levels can be in disjoint areas or in areas that overlap one another. In particular, for example, pressure levels include unavoidable or expected pressure drops. The same applies to temperature levels. The pressure levels indicated here in bar are absolute pressures.

All nitrogen taken from the high-pressure column and neither condensed nor recycled as reflux into it nor used as a liquid reflux to the low-pressure column, basically affects the separation in the low-pressure column because it is no longer available there as reflux. Such nitrogen is nitrogen taken from the air separation plant in the form of a liquid or gaseous nitrogen product (as is typically not the case in the present invention), and the nitrogen which is throttled and discarded as explained below. But this also applies internally compressed nitrogen, ie liquid nitrogen, which is taken from the high-pressure column, pressurized in a pump and evaporated in the main heat exchanger. Internal compaction is also explained, for example, in Häring, section 2.2.5.2, "Internal Compression".

An "argon discharge" is here generally understood as a measure in which a fluid is withdrawn from the low-pressure column which is enriched in argon with respect to an oxygen-rich liquid fed from the low-pressure column, in particular the low-pressure column bottoms product, i. For example, has at least twice, five times or ten times the argon content. An argon discharge further comprises, at least a portion of the in one

corresponding withdrawn fluid contained argon no longer in the

Attributed to low pressure column. In particular, the fluid becomes one

Subjected Argonabreicherung and only then returned to the low pressure column. Classic types of argon discharge are a transfer of a corresponding fluid into a crude argon column or argon discharge column, from which only an argon-poor, oxygen-rich fluid is returned to the low-pressure column. The advantageous effect of Argonausschleusung is due to the fact that the oxygen-argon separation for the discharged Argonmenge in the

Low pressure column is no longer necessary. The separation of argon from

Oxygen in the low-pressure column itself is generally expensive and requires a corresponding "heating" capacity of the main capacitor. If argon is discharged and thus omits the oxygen-argon separation or this is displaced, for example, in a crude argon or Argonausschleussäule, the corresponding amount of argon must not be separated in the oxygen section of the low pressure column and the heating power of the main capacitor can be reduced. Therefore, with the same yield of oxygen, either more air injected into the low-pressure column or more pressure nitrogen from the

High-pressure column are removed, which in turn provides energy benefits.

In a conventional crude argon column crude argon can be recovered and processed in a downstream pure argon column to an argon product. An Argonausschleussäule, however, serves primarily for Argonausschleusung to the purpose explained above. In principle, an "argon discharge column" can be understood to mean a separation column for argon-oxygen separation which is not suitable for

Extraction of a pure argon product, but for the discharge of argon used in high-pressure column and low-pressure column to be separated air. Their circuit differs only slightly from that of a classic crude argon column, but it contains significantly less theoretical soil, namely less than 40, in particular between 15 and 30. As a crude argon column is the sump area of a

Argon discharge column connected to an intermediate point of the low-pressure column and the argon discharge column is cooled by a top condenser, on its evaporation side typically relaxed bottom liquid from the

High-pressure column is initiated. An argon discharge column typically does not have a bottom evaporator.

Advantages of the invention

The present invention is based on the recognition that in one

Air separation plant designed primarily for the production of pure oxygen with a content of at least 90% or 95%, in particular from 99 to 99.96%, taken from the high-pressure column nitrogen in a certain amount, an isenthalpic relaxation, i. in particular a throttle relaxation, can be supplied and discarded. However, a throttle relaxation of other gaseous streams is, as also explained in detail below, advantageous. The present invention will be described primarily with reference to the nitrogen taken from the high-pressure column.

Although this does not lead to a reduction of energy consumption, however, can be increased by such removal at the same column diameter of the low pressure column, the capacity of the air separation plant according to the discarded nitrogen amount or the diameter of the column are reduced accordingly. This is particularly advantageous in standardized column diameters, as explained below.

The standardization of an air separation plant typically includes the

High-pressure column, the main condenser, the low-pressure column and, if present, the columns of the argon system. Therefore, the maximum capacity, ie the maximum demountable air volume, from the standard dimensions and the

Product spectrum (i.e., the respective amounts) of the air products taken from the rectification. In the regular design of an air separation plant, the components, in particular the distillation columns, are dimensioned such that no product is discarded. Is the product range outside of the

Standardization of selected product range, therefore, in a conventional air separation plants, the use and thus the capacity must be reduced. By discarding nitrogen in the present invention, this is no longer necessary. Another advantage of the present invention is that the low pressure column does not have to be made unnecessarily large or at

Transport limitations in height (transport height) the capacity can be increased.

As also recognized within the scope of the present invention, it is possible, alternatively or in addition to the removal and isenthalpic expansion of the nitrogen withdrawn from the high pressure column, for example feed air provided at the pressure level of the high pressure column, to provide isenthalic relaxation, i.

in particular a Drosselentspannung to supply to the pressure level of the low pressure column and feed into the low pressure column. In the distillation columns of an air separation plant, packings with different packing densities are used. The packing densities are

standardized and typically only comparatively coarse graduation available. Furthermore, the highest separation efficiency in the low-pressure column is typically required in its lower region. Both have the consequence that the low pressure column of an air separation plant at least in a middle range reserves in the

Has separation capacity. In other words, there are overcapacities in the separation performance in the low-pressure column in such areas, which can be used for the air fed in here. In this way, capacity reserves can be used in the context of the present invention.

It is understood that in all the aforementioned mentioned

Embodiments of the isenthalp relaxation must be subjected to a sufficient amount of fluid in order to achieve the respective advantageous effects or to show a corresponding effect at all. The respective gaseous material flows, be it nitrogen from the high-pressure column or another gaseous one Fluid, are therefore supplied in an appropriate amount of isenthalpic relaxation. In this case, a quantity of at least 500 standard cubic meters per hour has been found to be particularly advantageous. In an air separation plant in which, for example, about 500,000 standard cubic meters of air per hour used in total, ie compressed in the air separation plant (especially in the main air compressor) and cooled (especially in the main heat exchanger), this corresponds to 0.1% of the amount of air used.

In this way, the present invention is distinguished in particular from methods in which small amounts of gaseous fluids, for example components which are not condensable in a condensation chamber of a condenser evaporator, are withdrawn and, if appropriate, likewise subjected to isenthalpic expansion. By means of such an approach can be prevented in particular that such non-condensable components due to their low boiling point the

Functionality of the condenser evaporator adversely affect.

Such non-condensable components are, in particular, helium, neon and hydrogen. The content of these components in

atmospheric air is about 0.00052% (helium), about 0.0018% (neon) and about 0.00006% (hydrogen), so their total amount is 0.00238%. In the illustrated case, therefore, significantly lower amounts of substance, if any, would be fed to an isenthalpic expansion, since corresponding components are not available in greater quantities in uncondensed form. Furthermore, it is understood that within the scope of the present invention, the material stream or streams which are provided in gaseous form and subjected to isenthalpentation may also be subjected to expansion in addition to a stream of material optionally also provided in gaseous form and fed to an argon discharge column or crude argon column (see below) can be provided. In this way, the advantages mentioned can be achieved. For this reason, in the context of the present invention, the material stream (s) provided gaseously and subjected to isenthalpent expansion, with several material streams in each case, have an argon content of less than 1.5 mol%, in particular less than 1 mol%. In the context of the present invention, finally, the advantages mentioned can be achieved by using gaseous feed air which has been compressed to the pressure level of the high-pressure column and / or by using a material stream taken off in gaseous form from the high-pressure column. Therefore, the isenthalic relaxation always takes place starting from a corresponding one

Pressure level that is at the pressure level of the high pressure column or a pressure level that differs by no more than 1% of this.

Advantageously, the gaseous material stream (s) subjected to isenthalpic relaxation or are further provided at a temperature level corresponding to at least one temperature level present in the high pressure column. It may in particular be a temperature level at the top of the high-pressure column or at an extraction point of the or one of the isenthalp to relaxing gaseous streams from the

Act high-pressure column. It can also be a lowest temperature level to which air in the air separation plant is compressed. The gaseous material streams are or are advantageously fed at least at this temperature level to isenthalpic expansion, i. Although heated if necessary, before isenthalpen relaxation, as explained below, but not further cooled.

The present invention proposes a process for the cryogenic separation of air using an air separation plant having a distillation column system comprising a high pressure column operating at a first pressure level and a low pressure column operating at a second pressure level below the first pressure level. As already mentioned, the typical pressure level of a high-pressure column of an air separation plant, and thus also the first pressure level in the context of the present invention, in particular 4 to 6 bar, in particular about 5 bar. The low-pressure column is, as also mentioned, at the second pressure level, for example, 1, 3 to 1, 7 bar, in particular about 1, 5 bar operated. In the context of the invention are using the air in the

Air separation plant one or more gaseous streams formed and subjected to an isenthalp relaxation, starting from the first pressure level or a pressure level which is not more than 1 bar from the first

Pressure level is different, is performed, and in which a pressure difference of 3 to 6 bar is overcome. The pressure difference is in particular 3 to 5 bar, preferably 3.5 to 4.5 bar, for example about 4 bar. The isenthalpic expansion can be carried out in particular starting from a pressure level which differs by no more than 0.5 bar, 0.2 bar or 0.1 bar from the first pressure level. Further details and the associated advantages have already been explained. The pressure difference may in particular correspond to the difference between the first pressure level, that is to say the operating pressure of the high-pressure column, and a discharge pressure. In the case of isenthalp relaxation, it may in particular be a

Throttle relaxation act, as defined below. According to the invention, it is provided that the gaseous material stream (s) subjected to gaseous expansion comprises or comprise a quantity of fluid of at least 500 standard cubic meters per hour. As explained, the measures carried out according to the invention differ from conventional methods in which small amounts are not condensable

Components are removed from the condenser evaporator. The latter can be done in the context of the present invention additionally.

According to the invention, it is provided that the gaseous material stream (s) subjected to gaseous expansion has or have an argon content of not more than 1.5% mole percent, in particular not more than 1 mole percent. Therefore, any further streams which are processed in a crude argon column or argon discharge column (see below), as likewise possible in the context of the present invention, are not covered by this or these streams.

According to a particularly advantageous embodiment of the present invention, as mentioned, or the gaseous streams which is or are subjected to the isenthalp relaxation, is or become at a temperature level

provided that at least one present in the high-pressure column

Temperature level, as explained at the head or a sampling point from the high pressure column corresponds. The gaseous material streams are or will advantageously be at least at this temperature level of isenthalpy

Although supplied with relaxation, that is to say before the isenthalpic relaxation, heating may take place, but no further cooling. The temperature level at which the gaseous material streams or are formed is or is in particular above -200 ° C, preferably above -150 ° C, and especially below 100 ° C, preferably below 50 ° C. It can also be cooled to a lowest temperature level, to which air in a main heat exchanger of the air separation plant is cooled. Will be inserted as explained below

corresponding gaseous stream withdrawn from the high pressure column, the temperature level of its formation corresponds to that at the sampling point. If, however, a corresponding gaseous stream of compressed and cooled feed air is formed, the temperature level corresponds to its formation of the corresponding

Cooling temperature.

In the context of the present invention, the isenthalp relaxation can be carried out at a temperature level of 0 to -200 ° C, in particular a temperature level of -150 to -200 ° C, for example about -170 ° C, i. in particular on the basis of such a temperature level, ie at a typical rectification temperature of air. However, it is also possible, for example, to relax the isenthalpent at a temperature level of 0 to 100 ° C, in particular a temperature level of 10 to 50 ° C, for example, about 20 ° C, i. in particular on the basis of such a temperature level. In this case, a corresponding stream of material is typically previously in one

Main heat exchanger of the air separation plant heated. The advantage of a

Relaxation in the cold lies in the fact that this is cheaper from an energetic point of view. A relaxation in the warm, however, has the advantage of better buildability.

In the context of the present invention, the or one of the gaseous streams subjected or to be subjected to isenthalpic expansion, in particular compressed and cooled air, may or may be a gaseous nitrogen-rich fluid withdrawn from an upper region of the high-pressure column an atmospheric nitrogen-enriched gaseous fluid from an intermediate region of the high-pressure column. The "upper region" of the high-pressure column is, in particular, a region near or at the top of the high-pressure column which is free of separating internals, the "intermediate region" represents, in particular, an area otherwise provided with separating internals which is arranged between the top and bottom of the high-pressure column. Advantageously, within the scope of one embodiment of the present invention, a nitrogen-rich first material stream is formed using a nitrogen-rich first fluid which is taken off in gaseous form from the high-pressure column at the first pressure level. Using a second fluid, which is taken from the low-pressure column in gaseous form at the second pressure level, a second material flow is formed in a further embodiment of the present invention.

A "formation" of a material flow "using" a fluid may comprise both that exclusively the fluid mentioned is used for the provision of the material stream, and that the material flow is generated from a plurality of fluids. As also explained below and illustrated in the figure, a "second" stream in the context of the present invention can be formed, for example, exclusively using "impure nitrogen" from the top of the low-pressure column. However, it is also possible to form a corresponding "second" or "further" material stream with the additional use of an oxygen-rich stream.

In the context of the abovementioned embodiment of the present invention, the nitrogen-rich first stream and, if formed in the further embodiment, the second stream are permanently removed from the distillation column system. This is understood to mean that the said material flows are not in the

Are returned distillation column system or one of its columns. The nitrogen-rich first stream thus differs from streams, in the form of which, as far as known, for example, pressure nitrogen from the head of the

High pressure column deducted and fed into the low pressure column.

In the context of the present invention, it is provided that the nitrogen-rich first stream at least to a portion of the isenthalpen mentioned several times

Relaxation, in particular a Drosselentspannung, is supplied. The isenthalp or throttle-relieved nitrogen rich first stream or its part is discarded, ie it is not used as a product of the air separation plant. The amount of the nitrogen-rich first fluid taken from the high-pressure column is, for example, up to 20%, in particular up to 8%, and more particularly at least 1, 2, 3, 4 or 5% of the total amount of air fed into the distillation column system. A "throttling relaxation" in the parlance of the present invention is a relaxation in which a stream or a corresponding part is passed through one or more throttle valve and thereby undergoes a pressure reduction. In throttle relaxation can, but it must not be the only relaxation, which is subjected to the nitrogen-rich first stream in the present case. Throttling relaxation proves to be extremely cost-effective, especially for smaller amounts of nitrogen.

In the context of the present invention, the isenthalpe or throttling release of the first material flow or its isenthalpic or throttling release component is, in particular, brought to a third pressure level, which is in particular greater than or equal to the second pressure level, i. in particular greater than or equal to the pressure level of the second material flow or the low-pressure column, carried out. In particular, the third pressure level corresponds to the second pressure level. In this way, in particular the first material flow or its portion can be fed to the second flow of material after throttling relaxation. For example, it is possible to use a material stream formed thereby in a cleaning system of the air separation plant, for example as a regeneration gas for adsorbers. Alternatively or in addition to the isenthalpen or throttle relaxation of the first

Material stream is provided in the context of another embodiment of the present invention that cooled compressed air provided at the first pressure level and fed to a first portion in the high pressure column and fed to a second portion of the isenthalp relaxation, in particular a Drosselentspannung to the second pressure level and the low pressure column is fed. In particular, the provision of the compressed air at the first pressure level comprises that a portion of an amount of feed air compressed in a main air compressor to the first pressure level in a main heat exchanger is brought to a temperature level which is below or close to the liquefaction temperature of air. The advantages of a corresponding measure have already been explained above.

In principle, it is within the scope of the present invention, as already explained in more general form, possible to carry out the throttling relaxation of the first material stream before ("cold relaxation") and / or after ("warm relaxation") a heating of the first material stream or corresponding proportions , The cold relaxation is less expensive, since in this way no separate passage in the main heat exchanger or no additional heat exchanger is needed. A warm relaxation has the advantage that the second material flow can also be used as a product under pressure when needed.

The nitrogen-rich first fluid is advantageously taken from the high-pressure column at a first temperature level, and the nitrogen-rich first material stream is formed at the first temperature level. This first temperature level thus corresponds to the temperature of the fluid at the removal point from the

Low-pressure column.

In particular, in the context of the present invention, a proportion of the first material flow at a first temperature level at which the first fluid of the

High-pressure column is removed, which are subjected to isenthalp relaxation and / or a portion of the first stream can be heated from the first to a second temperature level and then subjected to the isenthalp relaxation. However, it is also possible to subject the first stream completely at the first or second temperature level of isenthalpic relaxation. The heating takes place in particular in a main heat exchanger

Air separation plant and in particular to a lying above 0 ° C (second) temperature level. The first temperature level is in particular from 0 to -200 ° C., in particular from -150 to -200 ° C., for example about -170 ° C. The second

Temperature level is in particular at 0 to 100 ° C, in particular 10 to 50 ° C, for example about 20 ° C.

Particular advantages can be achieved in the context of the present invention by an Argonausschleusung, in which the low pressure column is an argon

taken enriched fluid, depleted of Argon using an argon discharge column or crude argon column and at least partially fed back into the low pressure column. Characteristics of a crude argon column and an argon discharge column as well as the advantages of argon discharge have already been explained.

The second fluid, which is taken from the low-pressure column and used in the formation of the second material flow, may in particular be a nitrogen-rich fluid which is taken from the low-pressure column at the top, and which has a content of 96%. to 99.999 mole percent nitrogen and otherwise predominantly oxygen or argon. If no pure nitrogen from the low-pressure column is required, advantageously only impure nitrogen is taken off at the top. If pure nitrogen is required, the low-pressure column is designed with a further section, as also shown in the figures. In the latter case, advantageously two nitrogen-rich fractions are withdrawn from the low pressure column. The so-called impure nitrogen has a nitrogen content of about 96 to 99.99 mole percent of the so-called impure nitrogen content of at least 99.99% mole percent to 0.1 ppm oxygen. The second fluid can therefore also be a nitrogen

enriched fluid, which is taken from the low-pressure column via a side draw, and therefore has a correspondingly lower content of nitrogen.

The above-mentioned second stream formed in the context of one embodiment of the invention may also be carried out using an additional fluid, which is the

Low pressure column is taken in gaseous form, are formed. The additional fluid may be an oxygen-rich fluid, the low pressure column via a

Side take is taken. The present invention also relates to an air separation plant with a

A distillation column system comprising a high pressure column adapted for operation at a first pressure level and a low pressure column adapted for operation at a second pressure level below the first pressure level. The air separation plant according to the invention is characterized by means which are adapted to form one or more gaseous streams using the air in the air separation plant and an isenthalp relaxation from the first pressure level or a pressure level of not more than 1 bar of differs from the first pressure level, and thereby to overcome a pressure difference of 3 to 6 bar, wherein means are provided, which are adapted to the gaseous streams, or which is subjected to gaseous relaxation or in a quantity of fluid of at least 500 standard cubic meters per hour, and means are provided which are adapted to provide the gaseous material streams which are or are subject to gaseous expansion with an argon content of not more than 1.5 mole percent. The air separation plant according to the invention, which is advantageously set up for carrying out a method, as explained above, benefits in the same way from the advantages of the method according to the invention in its explained embodiments. Reference is therefore expressly made to the above explanations.

Brief description of the drawings

Figure 1 illustrates an air separation plant according to an embodiment of the present invention.

Detailed description of the drawings

FIG. 1 shows an air separation plant which is suitable for operation according to

Embodiment of the present invention is arranged. The air separation plant is designated 100 in total. For further details regarding the function of air separation plants and their components, reference should be made to the cited technical literature (see, for example, Haring, FIG. 2.3A and related explanations). In the air separation plant 100 feed air in the form of a stream a (AIR) is sucked by a main air compressor 101 in a feed air through a filter 102, there compressed to a first pressure level and a pre-cooling 103 and a purification 104, respectively. The compressed, precooled and purified feed air is further pressurized in the form of a stream b in a booster 105 with aftercooler 106. The air separation plant 100 may deviate from the illustrated example also be formed with main and Nachverdichter.

A first portion of the further pressurized in the booster 105 feed air is in the form of a stream c in a main heat exchanger 107 on a

Cooled intermediate temperature level and in a turboexpander 108, which is coupled to the booster 105, relaxed. A second portion of the further pressurized feed air in the booster 105 is in the form of a stream d in the

Main heat exchanger 107 cooled to a final temperature level and isenthalp relaxed in a throttle valve 109. The relaxed feed air of the streams c and d is combined to form a stream e and partly in the form of a stream f in a High pressure column 1 1 1 and partly in the form of a stream g in one

Low-pressure column 112 of a distillation column system 10, which further comprises a

Rohargonsäule 1 13, fed. The feed of the stream g in the low pressure column 112 is carried out under relaxation via a pressure relief valve 1 14th

From the bottom of the high-pressure column 11, an oxygen-enriched liquid in the form of a stream h is withdrawn, passed through a subcooler 15, partly used for cooling in a top condenser of the crude argon column 1 13 and finally fed to the low-pressure column 1 12.

From the top of the high-pressure column 11 1, a nitrogen-rich fluid in the form of a stream i is withdrawn. This is liquefied in part in the form of a stream k in a main condenser 116, which connects the high-pressure column 11 1 and the low-pressure column 1 12 heat-exchanging. From this, a first portion in the form of a stream I as return to the high-pressure column 1 11 is returned and a second portion in the form of a stream m passed through the subcooler 1 15 and fed to the low-pressure column 112.

The not liquefied in the main capacitor 1 16 portion of the stream i is in the example shown to a first portion in the form of a stream n the

Main heat exchanger 107 is supplied and heated there and expanded to a second portion in the form of a material flow o isenthalp via a throttle valve 1 17 and fed to a stream p. The stream p is a stream which is formed using impure nitrogen taken from the low pressure column 12 in the form of a stream j and passed through the subcooler 15. In the example shown, the stream p also comprises oxygen-rich fluid which is taken from the low-pressure column 112 in the form of a stream z.

A formed in this way collecting stream q is also the

Main heat exchanger 107 supplied and heated there. The collecting stream q is then partially blown off in the example shown to the atmosphere (ATM) and used in part in the pre-cooling 103 and the purification 104. Even after heating in the main heat exchanger 107, in the example shown, a portion of the material flow r is branched off, expanded by means of an expansion valve 118 and fed to a stream s. The stream s is a Stream which is formed using further nitrogen-rich fluid taken from the low pressure column 112, passed through the subcooler 15 and heated in the main heat exchanger 107. A collecting stream t formed in this way can be used like the collecting stream q.

In both cases (i.e., the feeding of a portion of the stream n upstream of the heat exchanger 107 and downstream of the heat exchanger 107 to another stream, here the stream p and the stream s), a portion of the corresponding nitrogen-rich fluid is discarded. Both possibilities can alternatively be used in embodiments of the present invention. A remaining portion of the nitrogen-rich fluid can be used, for example, in the form of a stream of material u as a sealing gas for the compressors used (seal gas).

The low pressure column 1 12 oxygen-rich liquid is removed in the form of a stream v and by means of a pump 1 19 liquid pressure increases (internal compression). A portion thereof is heated in the form in the main heat exchanger 107, thereby converted into the gaseous or supercritical state and as gaseous

Oxygen pressure product (GOX IC1) provided. Another part is optionally supercooled in the subcooler 1 15 and provided as a liquid oxygen product (GOX).

From a liquid retention tank at the top of the low pressure column 112, a nitrogen-rich fluid withdrawn liquid, partly as reflux to the

Low pressure column 112 recycled and provided in part in the form of a stream w as a liquid nitrogen product (LIN). Head gas from the head of the

Crude argon column 1 13 is liquefied, partly recycled as reflux to the crude argon column 1 13 and partly in the form of a stream of material x to the atmosphere

blown off. In the example shown, an argon-rich fluid in the form of a stream of material y can also be withdrawn from the crude argon column 1 13 in liquid form and made available as a liquid argon product (LAR).

As illustrated in the form of a stream 'j' can show in the

Air separation plant from a condensation chamber of the main capacitor 1 16 or via a corresponding outlet non-condensing components, as mentioned in particular helium, neon and hydrogen, are deducted. In this way it can be ensured that these are the functioning of the Due to their low boiling points, the main condenser is not adversely affected. The flow of material j 'can in particular be supplied to the substance stream.

Claims

claims

Process for the low temperature decomposition of air using a

An air separation plant (100) comprising a distillation column system (10) comprising a high pressure column (1 1 1) operated at a first pressure level and a low pressure column (1 12) operating at a second pressure level below the first pressure level, characterized in that using the air in the air separation plant (100) one or more gaseous streams are formed and subjected to an isenthalpic expansion, starting from the first pressure level or a pressure level differing by no more than 1 bar from the first pressure level , and in which a pressure difference of 3 to 6 bar is overcome, wherein the gaseous material streams which are or are subjected to the gaseous expansion comprises or comprise a fluid quantity of at least 500 standard cubic meters per hour, and wherein the or the gaseous streams, or the gaseous relaxation or having an argon content of not more than 1.5 mole percent.

A process as claimed in claim 1, wherein the gaseous material stream (s) subjected to isenthalpic relaxation is or are placed on a

Temperature level is provided or at least one in the high-pressure column (1 1 1) present temperature level or a lowest temperature level, is cooled to the air in the air separation plant (100), wherein the or the gaseous material flows at least at this temperature level of isenthalpen Relaxation is or will be supplied.

Process according to Claim 1 or 2, in which the or one of the gaseous streams subjected to isenthalpic expansion is or are compressed and cooled air, a gaseous, nitrogen-rich fluid emerging from an upper region of the high-pressure column (11). is removed, and / or a nitrogen-enriched gaseous fluid from a

Intermediate region of the high pressure column comprises or include.

4. The method according to any one of the preceding claims, wherein the isenthalp relaxation is carried out at a temperature level of 0 to -200 ° C.

5. The method according to any one of claims 1 to 3, wherein the isenthalp relaxation is carried out at a temperature level of 0 to 100 ° C.

6. The method according to any one of the preceding claims, wherein using a nitrogen-rich first fluid, which is the gaseous withdrawn from the high pressure column (1 1 1) at the first pressure level, a nitrogen-rich first stream is formed and wherein the first stream at least one

Subjected to isenthalpic relaxation and the

Distillation column system is permanently withdrawn.

7. The method of claim 6, wherein a portion of the first material stream at a first temperature level at which the first fluid of the high pressure column (11 1) is removed is subjected to isenthalpic relaxation and / or in which a portion of the first material stream of the first to a second

Temperature level is heated and then subjected to the isenthalp relaxation, or in which the first stream is completely subjected to the first or second temperature level of the isenthalp relaxation.

8. The method of claim 7, wherein using a second fluid, the low pressure column (1 12) is removed in gaseous form at the second pressure level, a second stream is formed and in which the second stream is permanently withdrawn from the distillation column system.

9. The method according to claim 8, wherein the first stream or its the

Isenthalpen relaxation subjection after the isenthalpen relaxation is fed to the second stream.

10. The method according to any one of the preceding claims, wherein the low pressure column withdrawn an argon-enriched fluid, using a

Argon effluent column or crude argon column (1 13) depleted of argon and at least partially fed back into the low pressure column (112).

1 1. A process according to any one of claims 7 or 8, wherein the second fluid is a nitrogen-rich fluid withdrawn from the low pressure column (1 12) at the top and having a content of 96 to 99.999 mole percent nitrogen and otherwise predominantly oxygen and argon.

12. The method according to any one of claims 7 or 8, wherein the second fluid is a nitrogen-enriched fluid, which is the low-pressure column (1 12) removed via a side draw. 13. The method according to any one of claims 10 or 1 1, wherein the second stream further using an additional fluid, the

Low pressure column (1 12) is removed in gaseous form, is formed.

14. The method of claim 13, wherein the additional fluid is an oxygen-rich fluid, which is the low-pressure column (1 12) removed via a side draw, and which has predominantly oxygen.

Air separation plant (100) with a distillation column system (10) having a high pressure column (1 1 1), which is adapted for operation at a first pressure level, and a low pressure column (1 12), for operation at a second pressure level below of the first pressure level, characterized in that means are provided which are adapted to form one or more gaseous streams using the air in the air separation plant (100) and an isenthalpic relaxation from the first pressure level or a pressure level subjected to not more than 1 bar from the first pressure level, thereby to overcome a pressure difference of 3 to 6 bar, and means being provided which are adapted to the one or more gaseous ones

Streams that is or are subjected to the gaseous relaxation, with a fluid amount that is at least 0.1 percent of the

Air separation unit (100) supplied to supply air, and means are provided which are adapted to provide the gaseous streams, which is or are subjected to the gaseous relaxation with an argon content of not more than 1 mole percent.