Method and air separation plant for extracting one or several air products

Abstract

The invention relates to a method for extracting one or several air products, in which method an air separation plant is used, which has a column system (10) having a pressure column (11), wherein the pressure column (11) is operated in a pressure range of 4 to 7 bar, wherein air is supplied to the column system (10) and separated therein, wherein at least 90% of the air supplied to the column system (10) as a whole is compressed to a base pressure level, which is more than 5 bar above the pressure range in which the pressure column (11) is operated, wherein nitrogen-rich gas is extracted from the pressure column (11), and wherein, at least in a first operating mode, more air is compressed to a pressure level which is higher than the base pressure level, expanded and heated without separation in the column system (10). It is provided that, at least in the first operating mode, a portion of the nitrogen-rich gas extracted from the pressure column (11) is fed to the more air upstream of the expansion. The invention also relates to a corresponding air separation plant.

Description

[0001] The present invention relates to a method for extracting one or more air products and an air separation apparatus according to the corresponding preamble of the independent claim. Background of the Invention

[0003] The preparation of liquid or gaseous air products by separating air at low temperatures in an air separation device is known and, for example, by H.-W., Wiley-VCH Publishing Company, 2006. The book "Industrial Gases Processing" specifically describes this in Chapter 2.2.5, "Cryogenic Rectification".

[0004] Traditional air separation equipment includes a column system, which can be designed as a two-column system, particularly a twin-column system, but can also be designed as a three-column or multi-column system. In addition to distillation columns for extracting liquid and / or gaseous nitrogen and / or oxygen, i.e., distillation columns for nitrogen-oxygen separation, distillation columns for extracting other air components, especially rare gases, can also be installed.

[0005] The distillation columns in the aforementioned column system operate at different pressure levels. A known two-column system has a so-called pressure column (also known as a high-pressure column, intermediate-pressure column, or lower column) and a so-called low-pressure column (upper column). The high-pressure column typically operates at pressure levels of 4 bar to 7 bar, particularly about 5.6 bar, while the low-pressure column typically operates at pressure levels of 1 bar to 2 bar, particularly about 1.4 bar. In some cases, even higher pressure levels may be used in both distillation columns. The pressures described here and below are absolute pressures at the top of the respective given column.

[0006] The object of the present invention is to improve the method for separating air at low temperatures and providing air products, and particularly to implement it as more energy-efficient. Summary of the Invention

[0007] This objective is achieved by a method for extracting one or more airborne products and an air separation apparatus having the features of the independent claim. The embodiments are the subject of the respective dependent claims and the following description.

[0008] The following text first explains some basic principles of the invention and defines the terminology used to describe the invention.

[0009] For air separation, the so-called Main Air Compressor / Booster Air Compressor (MAC-BAC) method or the so-called High Air Pressure (HAP) method can be used. The MAC-BAC method is more traditional, but in recent years, the HAP method has been increasingly used as an alternative.

[0010] The primary air compressor / secondary compressor method is characterized in that only a portion of the total intake air volume supplied to the tower system is compressed to a pressure level significantly higher than the pressure level of the pressure tower, i.e., at least 3, 4, 5, 6, 7, 8, 9, or 10 bar higher, and further higher than the highest pressure level used in the tower system. Another portion of the intake air volume is compressed only to the pressure level of the pressure tower, or to a pressure level differing from that of the pressure tower by no more than 1 to 2 bar, and is fed into the pressure tower at that pressure level without expansion. An example of such a primary air compressor / secondary compressor method is... (See above) in the book Figure 2 As shown in .3A.

[0011] Conversely, in the high-pressure method, the entire intake gas supplied to the tower system is compressed to a pressure level significantly higher than that of the pressure tower, i.e., 3, 4, 5, 6, 7, 8, 9, or 10 bar higher, and further higher than the highest pressure level used in the tower system. This pressure difference can, for example, reach a maximum of 14, 16, 18, or 20 bar. The high-pressure method has been described numerous times and is known, for example, from EP 2 980 514 A1 and EP 2 963 367 A1.

[0012] For information on devices or equipment used in air separation equipment, please refer to relevant professional literature, such as... (See above), especially section 2.2.5.6, “Apparatus”. In the following text, for clarification and clearer definition, some aspects of the corresponding apparatus will be explained in more detail.

[0013] In air separation equipment, a multi-stage turbo compressor is used to compress all the separated air; this turbo compressor is referred to herein as the "main air compressor" or simply the "main compressor." The mechanical structure of the turbo compressor is generally a well-known technical field for those skilled in the art. In a turbo compressor, the medium to be compressed is compressed by means of turbine blades or impellers arranged on a turbine or directly on a shaft. Here, the turbo compressor forms a structural unit, although this structural unit in a multi-stage turbo compressor may have multiple compression stages. Compression stages here typically include corresponding arrangements of turbines or turbine blades. All these compression stages may be driven by the same shaft. However, they can also be configured to be driven in groups by different shafts, wherein the shafts may also be connected to each other via a reduction gear.

[0014] The main air compressor is characterized by compressing all the air fed into the tower system and used for the preparation and separation of air products; that is, compressing all the added air. A "secondary compressor" may also be provided, but in this secondary compressor, only a portion of the air compressed by the main air compressor is increased to a higher pressure. This compressor may also be designed as a turbo compressor. To compress a portion of the air, other turbo compressors are typically provided; these other turbo compressors are also called booster compressors, but they compress only to a relatively small extent compared to the main or secondary air compressor. In high-pressure methods, a secondary compressor may also be present; however, this secondary compressor compresses a portion of the air starting from a correspondingly higher pressure level.

[0015] Air can also be expanded at several points in an air separation device; for this purpose, among other things, an expander in the form of a turbo expander, also referred to herein as an "expansion turbine," can be used. The turbo expander can also be connected to and drive a turbo compressor. If there is no external power supply, i.e., only one or more turbo compressors are driven by one or more turbo expanders, the term "turbocharger" or "boost turbine" can also be used for such an arrangement. In a turbocharger, the turbo expander (expansion turbine) and the turbo compressor (boost compressor) are mechanically connected, which can be achieved at the same rotational speed (e.g., via a common shaft) or at different rotational speeds (e.g., via an intermediate transmission gear).

[0016] In typical air separation equipment, corresponding expansion turbines are present at various points for cooling and liquefying the feed stream. In this case, the turbine is specifically the so-called Joule-Thomson turbine, Claude turbine, and Lachmann turbine. For supplementary references to the functions and uses of the corresponding turbines, see, for example, FGKerry's Handbook of Industrial Gases, "Gas Separation and Purification," published by CRC Presse in 2006, particularly Chapter 2.4, "Contemporary Liquefaction Cycles," Chapter 2.6, "Theoretical Analysis of the Claude Cycle," and Chapter 3.8.1, "The Lachmann Principle."

[0017] In the language used herein, liquids, gases, or liquids that are also in a supercritical state may be rich in or lack one or more components, where “rich in” can mean an amount of at least 75%, 90%, 95%, 99%, 99.5%, 99.9%, or 99.99% on a molar, weight, or volume basis, and “lacking in” can mean an amount of at most 25%, 10%, 5%, 1%, 0.1%, or 0.01%. The term “major” may correspond to the definition of “rich in” given above, but specifically refers to an amount of more than 90%. For example, if “nitrogen” is mentioned herein, it may refer to a pure gas, but it may also refer to a nitrogen-rich gas.

[0018] In the following text, the terms "pressure level" and "temperature level" are used to characterize pressure and temperature, thereby indicating that the concepts of the invention need not be implemented using pressure and temperature in the form of precise pressure or temperature values. However, such pressure and temperature typically move within a certain range, such as, for example, an average value ±1%, 5%, or 10%. Different pressure and temperature levels may be in non-overlapping or overlapping ranges. In particular, pressure levels, for example, include unavoidable or anticipated pressure losses, such as due to cooling effects. The corresponding terms apply to temperature levels. Unless otherwise stated, pressure levels in bar herein refer to absolute pressure.

[0019] Features and advantages of the present invention

[0020] While the HAP method is generally more cost-effective than the traditional MAC-BAC method in terms of manufacturing and some operating costs due to the fewer rotating machines and higher pressures, it has many disadvantages in terms of energy requirements.

[0021] In devices with very high liquid volumes associated with internal compression flow (see also the cited literature at the beginning for more information on internal compression) (i.e., the relative amount of air product extracted from the device is liquid), or when there is (essentially) only liquid product, the so-called “excess air” method is used (see also...) Figure 1 (and related explanations).

[0022] This invention is based on the understanding that a modification of the corresponding "excess air" method offers particular advantages. In such methods, generally, a portion of the overall compressed and cooled air is expanded by a turbine, but instead of being fed (as in a Joule-Thomson turbine) into a pressure tower or (as in a Lachmann turbine) a low-pressure tower and separated there, it is reheated in the main heat exchanger to the temperature level of the warm side of the same main heat exchanger and discharged from that device without separation. The expansion can be carried out, in particular, at atmospheric pressure. Since the air that has been correspondingly heated has been purified, in principle, this air can be fed back to the additional air to be compressed, i.e., upstream of the main heat exchanger, without being discharged into the atmosphere. The corresponding method is also combined with the already explained HAP method, known from US 3,905,201 A, WO 2014 / 154339 A2 and EP 3 343 158 A1.

[0023] In an example that can also be used in the context of this invention, air can be compressed to a high pressure, such as 23 bar (HAP), in a main air compressor. The air can then be further compressed in one or two booster compressors (typically connected in series). The booster compressors are driven by turbines. The turbines expand from a pressure higher than the HAP pressure, achieved by the booster compressors, to a pressure column pressure (e.g., 5.6 bar). This air is then separated into the necessary pressure column air (which is required for distillation) and an excess portion. The excess portion (“excess air”, also referred to hereinafter as excess air) is heated in a main heat exchanger and supplied to a second turbine, which drives a second booster compressor or (depending on the ratio of liquid production to internal compression) generator and expands to a pressure slightly above ambient pressure. This portion is then heated in the main heat exchanger and, for example, blown into the environment.

[0024] The present invention enables improvements to the performance of the HAP method (in terms of total cost of ownership (TCO)) through measures explained below, particularly in cases with high liquid production, where the use of an excess air turbine is reasonable. Specifically, the invention is applicable to situations where, based on the amount of internally compressed air product, at least 35%, particularly 40% or 50%, of the liquid air product is extracted from the air separation unit from time to time.

[0025] In this invention, the so-called blow-in equivalent is not fully utilized in many devices and operating cases. It is known that increasing the blow-in equivalent can improve energy absorption.

[0026] The term "blown-in air volume" refers to compressed air that is expanded through a typical Lachmann turbine (blown-in turbine) and then fed ("blown in") into the low-pressure column. Air expanded into the low-pressure column in this manner interferes with distillation, thus limiting the amount of expandable air in the blown-in turbine and the cooling capacity that can be generated for a corresponding unit in this way. Nitrogen-rich air products extracted from the pressure column and discharged from the air separator also affect distillation in this manner. The amount of air blown into the low-pressure column plus the amount of nitrogen extracted from the pressure column and discharged from the air separator can be expressed as a ratio to the total air fed into the column system. The resulting value is the "blown-in equivalent".

[0027] Therefore, the blow-in equivalent is defined as the amount of compressed air compressed and expanded by a blow-in turbine into the low-pressure column of the air separator, plus the amount of nitrogen, which is extracted from the pressure column where appropriate and is neither returned to the pressure column as a liquid recirculation nor fed into the low-pressure column as a liquid recirculation, relative to the total compressed air fed into the column system. The nitrogen extracted from the pressure column can be pure nitrogen or substantially pure nitrogen from the top of the pressure column, but can also be a nitrogen-rich gas with a slightly lower nitrogen content extracted from the region below the top of the high-pressure column.

[0028] As previously mentioned, increasing the blow-in equivalent improves energy absorption. In the context of this invention, where the HAP method with an excess air turbine is used, the increase is achieved by expanding, as required, at least a portion of the pressurized nitrogen from the pressurization tower, or all of the nitrogen-rich fluid from the pressurization tower, in the excess air turbine.

[0029] The required air volume to provide the desired product is increased exponentially by increasing the blow-in equivalent. However, increasing the blow-in equivalent also reduces argon production. To optimize this, there exists an optimal value at which the blow-in equivalent can be exhausted.

[0030] The optimal value ranges from 10 to 20, depending on the energy source and argon grade. For equipment without argon production, the optimal value is significantly higher.

[0031] In general, the present invention proposes a method for extracting one or more air products, wherein an air separation device is used, the air separation device having a tower system having a pressure tower, wherein the pressure tower operates in a pressure range of 4 bar to 7 bar, for example 5 bar to 6 bar, particularly about 5.6 bar, wherein air is supplied to the tower system and separated in the tower system, and wherein at least 90%, particularly more than 95% or all of the air supplied to the tower system is compressed to a base pressure level, which is more than 5 bar higher than the pressure range in which the pressure tower operates, for example 20 bar to 30 bar, particularly about 23 bar. Thus, as described several times above, the HAP method is used. Nitrogen-rich gas is extracted from the pressure tower, and at least in a first operating mode, more air is compressed to a pressure level above the base pressure level, expanded and heated in the tower system without separation. In the context of the present invention, at least in this first operating mode, a portion of the nitrogen-rich gas extracted from the pressure tower is fed to this more air upstream of the expansion. In this embodiment, the feeding can be performed before the additional air is heated, in which case the heating of the additional air and the heating of the fed nitrogen-rich gas are performed simultaneously, particularly in the main heat exchanger. However, the feeding can also be performed after the additional air is heated, in which case the additional air and the fed nitrogen-rich gas are heated separately beforehand, particularly in the main heat exchanger. As embodiments of the invention, the two alternatives will be explained in more detail below.

[0032] By feeding the nitrogen-rich gas extracted from the pressure tower to the excess air, the blow-in equivalent can be better depleted. This feeding (the amount of which depends on the product conditions and the corresponding optimal blow-in equivalent) reduces the necessary excess air. The power of the turbine used to expand the excess air remains approximately constant because the additional amount of nitrogen-rich gas extracted from the pressure tower compensates for the reduction in excess air.

[0033] Because the blow-in equivalent is increased in the context of this invention, the amount of air used for distillation is increased. However, the overall amount of air required at the main air compressor is reduced. Depending on the product, the reduction can be as high as about 6%. This reduction is directly reflected in energy savings. However, increasing the blow-in equivalent also reduces argon production, which, while reducing overall costs, also decreases production.

[0034] This invention can be performed in different operating modes, wherein the previously described "first" operating mode may also be the only operating mode. Conversely, in a method variant, a second operating mode may be provided, wherein more air is also compressed to a pressure level above the baseline pressure level, expands and heats in the tower system without separation (i.e., using excess air), and wherein, in the second operating mode, the nitrogen-rich gas extracted from the pressure tower is not fed into the additional air. In this embodiment, if an increase in argon production is required, the blow-in equivalent may be temporarily reduced, for example, in the second operating mode.

[0035] Finally, a third operating mode can also be configured. (Numbers are given here for illustrative purposes only; a second operating mode is not necessary, and the method may, for example, include only the first and third operating modes.) In the third operating mode, no more air is compressed to a pressure level higher than the baseline pressure level, expands and heats within the tower system without separation (i.e., no excess air is used), and in the third operating mode, instead of more air, a portion of the nitrogen-rich gas extracted from the pressure tower expands and heats. In this way, for example, when a smaller amount of nitrogen product is to be produced, when the equipment needs to operate under high energy optimization, and / or when argon production is not critical, the blow-in equivalent can be correspondingly increased in the third operating mode. Therefore, when the blow-in equivalent is maximized, argon production is minimized.

[0036] In one embodiment of the invention, excess air is supplied sequentially to the main heat exchanger of the air separation device on the warm side at a pressure level above the baseline pressure level, extracted from the main heat exchanger at a first intermediate temperature level, and subjected to a first turbine expansion; supplied to the main heat exchanger on the cold side, extracted from the main heat exchanger at a second intermediate temperature level, and subjected to a second turbine expansion; supplied to the main heat exchanger at a third intermediate temperature level, and extracted from the main heat exchanger on the warm side. Thus, two turbine expansion steps are performed, and heating begins in the main heat exchanger between these two turbine expansion steps, so that the expansion coolness generated during expansion can be used in the main heat exchanger.

[0037] Specifically, the nitrogen-rich gas extracted from the pressure tower can be fed to more air, i.e., a portion of the excess air, together with the more air, and supplied to the main heat exchanger on the cold side after the first turbine expansion, undergoing the second turbine expansion, and supplied to the main heat exchanger at a third intermediate temperature level, and extracted from the main heat exchanger on the warm side. In other words, the nitrogen-rich gas is heated together with the more air. In a further embodiment, the nitrogen-rich gas extracted from the pressure tower can also be fed to more air, i.e., a portion of the excess air, and supplied to the main heat exchanger on the cold side, extracted from the main heat exchanger on the warm side, and fed to more air at a second intermediate temperature level and before the second turbine expansion. That is, separate heating is performed in this embodiment.

[0038] In the context of this invention, as previously stated, the base pressure level (HAP pressure) can be from 11 bar to 28 bar, particularly from 16 bar to 24 bar, for example, about 23 bar. Pressure levels higher than the base pressure level, i.e., the pressure level to which more air, i.e., the air used to provide excess air, is compressed, can be increased in each subsequent booster compressor, particularly by 1.1 to 1.6 times, specifically from 22 bar to 50 bar, for example, from 22 bar to 30 bar in the device described below, in which the second turbine expansion of the excess air takes place in a turbine connected to the generator, and from 35 bar to 50 bar in the device described below, in which the second turbine expansion of the excess air takes place in a turbine connected to the booster compressor. As previously stated, the pressure range for pressure tower operation can particularly be from 4 bar to 7 bar, for example, from 5 bar to 6 bar, particularly about 5.6 bar. The main heat exchanger can operate at a temperature level of 0°C to 50°C on the warm side and at a temperature level of -150°C to -177°C on the cold side. The first intermediate temperature level mentioned above can be -120°C to -90°C, the second intermediate temperature level can be -20°C to 30°C, and the third intermediate temperature level can be -110°C to -60°C. The first turbine expansion can be performed at a pressure level of 4 bar to 7 bar, and the second turbine expansion can be performed at a pressure level of 100 mbar to 500 mbar above atmospheric pressure.

[0039] In the context of this invention, one or two booster compressors can be used to compress more air, i.e., air used to provide excess air, to a pressure level above the baseline pressure level. This is achieved by using at least one of the expanders to drive one or more of the booster compressors used in the first and second turbine expansions described above. In other words, when using one booster compressor, the expander used in the first or second turbine expansion can be used to drive it; or when using two booster compressors, the expander used in the first turbine expansion can be used to drive one of the booster compressors, and the expander used in the second turbine expansion can be used to drive the other booster compressor. The corresponding allocation relationship is arbitrary. As previously mentioned, one of the expander compressors can also be braked, for example by means of a generator or other means, in which case typically only one booster compressor is used to compress more air to a pressure level above the baseline pressure level.

[0040] In any case, the tower system used in the context of this invention may have a low-pressure tower operating in a pressure range of 1 bar to 1.7 bar, and an argon extraction section having at least one additional tower. As previously mentioned, argon extraction is affected by an increase in the blow-in equivalent. This can be flexibly adjusted as needed, particularly by using several operating modes.

[0041] Additional air, which can be compressed to a pressure level higher than the baseline pressure level, expands and heats in the tower system without separation, i.e., air used as excess air, is compressed together with the air fed into the tower system to a pressure level higher than the baseline pressure level. Specifically, a first portion of the air fed into the tower system and the air compressed together with additional air to a pressure level higher than the baseline pressure level is cooled and fed into the tower system without undergoing the first and second expansions, and a second portion is separated in liquefied form after the first expansion and fed into the tower system.

[0042] The present invention also relates to an air separation device. Features and advantages of this air separation device can be found in the corresponding independent claims. In particular, such an air separation device is adapted for implementing one or more methods described in the foregoing construction and has tools designed accordingly. Relevant features and advantages are clearly described above.

[0043] The invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. Attached Figure Description

[0044] Figure 1 A simplified diagram illustrates an air separation device not implemented according to the present invention.

[0045] Figure 2 A simplified diagram illustrates an air separation device implemented according to an embodiment of the present invention.

[0046] Figure 3 A simplified diagram illustrates an air separation device implemented according to an embodiment of the present invention.

[0047] In these figures, identical or similar elements are given with the same reference numerals and will not be explained again for clarity. Parts of components shown identically in several figures are not repeatedly labeled with reference numerals. Equipment components may also represent corresponding method steps, thus the following description of the air separation equipment also refers to the corresponding methods. Detailed Implementation

[0048] Figure 1 An air separation device not implemented according to the present invention is shown in the form of a simplified process flow diagram.

[0049] According to Figure 1 In the air separation device, air is drawn from the atmosphere A via a filter 2 by a main air compressor 1 and compressed to the baseline pressure level described previously. The compressed air stream a, supplied in this way, is cooled and water W is separated in a heat exchanger (not separately drawn) before being supplied to an adsorber station 3, where unwanted components such as water and carbon dioxide are removed. The compressed air stream a is then split into two streams, b and c.

[0050] At the warm end, spur stream b is supplied to the main heat exchanger 4, and this spur stream is extracted at the cold end. Spur stream c is further compressed using two booster compressors 5 and 6, and then supplied to the main heat exchanger 4 again at the warm end. Spur stream d of spur stream c is extracted from the main heat exchanger 4 at the cold end. Spur streams b and d are throttled and expanded, in which at least partial liquefaction occurs, and purified and fed into the pressure tower 11 of the tower system 10 as a stream not drawn separately.

[0051] In addition to the pressure column 11, the column system 10 also includes a low-pressure column 12, which is connected to the pressure column 11 in a dual-column configuration and thermally coupled via a main condenser 13. As another part of the column system 10, a subcooled countercurrent condenser 14 and a conventionally designed argon extraction section 15 are provided, by which pure argon X can be extracted. The latter operates as described numerous times in professional literature. In both the pressure column 11 and the low-pressure column 12, cryogenic distillation is performed at the respective distillation pressure levels.

[0052] A further fraction e, derived from fraction c in the main heat exchanger 4 at an intermediate temperature level, expands in an expansion turbine 7 connected to a booster 5, thereby partially liquefying it, and is fed into a separator 9, where it forms a liquid phase and a gas phase. The liquid phase is directed as a feed stream f through a subcooled countercurrent unit 14 and subsequently fed into a low-pressure tower 12. The gas phase is split into two fractions, g and h.

[0053] The split stream g is fed into pressure tower 11. Conversely, the split stream h is supplied to the main heat exchanger 4 at the cold end and extracted from the main heat exchanger near the warm end. Subsequently, this split stream is expanded in an expansion turbine 8 connected to a booster compressor 6, and supplied to the main heat exchanger 4 again at an intermediate temperature level, extracted from the main heat exchanger at the warm end, and discharged from the device. This is the so-called excess air, also referred to herein as H. Since the split stream h includes already purified air, it can be recompressed, for example, in the main air compressor 2, and used to form compressed air stream a, thereby reducing the purification effort.

[0054] A nitrogen-rich top gas is formed at the top of pressure tower 11, a portion of which is heated in the main heat exchanger 4 as a gaseous stream i and discharged from the air separator as pressure product I. Another portion is at least partially condensed in the main condenser 13. The first portion (not shown) is directed as reflux from the formed condensate back to pressure tower 11, the second portion is provided as internally compressed nitrogen product K as a stream k, and the third portion is directed as a stream m through the subcooling counterflow unit 14 and fed as reflux into the low-pressure tower 12 at its top.

[0055] The low-pressure column 12 is primarily supplied with the bottom liquid from the pressure column 11, which is extracted from the pressure column in the form of stream o. In the example shown, the bottom liquid from the pressure column 11 is used to cool the top condensate in the argon extraction section 15, where it is partially evaporated. The evaporated portion and the unevaporated portion (shown here as stream p) are transferred to the low-pressure column 12. The argon extraction section 15 is connected to the low-pressure column 12 in a material manner via stream q, which is not explained in more detail here. Additionally, liquid air is fed into the low-pressure column 12 in the form of stream n, which is extracted directly from the pressure column 11 below the inlet points of streams b and d and is directed through the subcooled countercurrent unit 14.

[0056] The bottom liquid from low-pressure column 12 can be extracted from the low-pressure column as stream r, with a portion supplied as liquid nitrogen S as stream s and another portion supplied as internally compressed products T1 and T2 as stream t. Gaseous nitrogen can be extracted from the top of low-pressure column 12 as stream u, and liquid nitrogen as stream v. The latter can be supplied as liquid nitrogen V, or a fraction of stream m can be supplied as pressurized liquid nitrogen M.

[0057] Figure 2 A simplified diagram illustrates an air separation device implemented according to an embodiment of the present invention. The air separation device is generally represented by 100 and includes... Figure 1 All components of the air separation device are shown in the image.

[0058] In an air separation device (as shown here in the form of a flow w), at least in one operating mode, a branch of flow i can be fed to flow h, and heated and expanded together with that branch in the manner explained. In other operating modes, the formation of flow w can be prevented, or flow w can completely replace flow h.

[0059] Figure 3 A simplified diagram illustrates an air separation device implemented according to a further embodiment of the present invention. The air separation device is generally represented by 200 and includes... Figure 2 All components of the air separation device 100 shown are provided, however, a generator G is provided instead of a booster compressor 6. Therefore, the airflow c is compressed only by means of the booster compressor 5.

[0060] Figure 4 A simplified diagram illustrates an air separation device implemented according to a further embodiment of the present invention. The air separation device is generally represented by 300 and includes... Figure 2 All components of the air separation device 100 shown in the figure, however, are different from the latter, where instead of the latter, the material flow w branches off from the material flow i on the warm side of the main heat exchanger 4 and feeds the material flow x to the material flow h.

Claims

1. A method for extracting one or more air products, wherein an air separation device is used, the air separation device having a tower system (10) having a pressure tower (11), wherein, The pressure tower (11) operates in a pressure range of 4 bar to 7 bar, wherein air is supplied to the tower system (10) and separated in the tower system (10), wherein at least 90% of the air supplied to the tower system (10) is compressed to a base pressure level, which is more than 5 bar higher than the pressure range in which the pressure tower (11) operates, wherein nitrogen-rich gas is extracted from the pressure tower (11), and wherein, at least in a first operating mode, more air is compressed to a pressure level higher than the base pressure level, expands and heats in the tower system (10) without separation, wherein, at least in the first operating mode, a portion of the nitrogen-rich gas extracted from the pressure tower (11) is fed to the more air upstream of the expansion, and in the second operating mode, the more air is also compressed to a pressure level higher than the base pressure level, expands and heats in the tower system (10) without separation, and in the second operating mode, the nitrogen-rich gas extracted from the pressure tower (11) is not fed to the more air.

2. The method of claim 1, wherein the expansion of the additional air is performed in an expander.

3. The method according to claim 1, wherein in the third operating mode the additional air is not compressed to a pressure level higher than the base pressure level, expands and heats in the tower system (10) without separation, and in the third operating mode, instead of the additional air, a portion of the nitrogen-rich gas extracted from the pressure tower (11) is expanded and heated.

4. The method according to any one of claims 1 to 3, wherein the additional air is supplied sequentially on the warm side to the main heat exchanger (4) of the air separation device at a pressure level higher than the base pressure level, extracted from the main heat exchanger (4) at a first intermediate temperature level, subjected to a first turbine expansion; supplied on the cold side to the main heat exchanger (4), extracted from the main heat exchanger (4) at a second intermediate temperature level, subjected to a second turbine expansion; supplied to the main heat exchanger (4) at a third intermediate temperature level, and extracted from the main heat exchanger (4) on the warm side.

5. The method according to claim 4, wherein a portion of the nitrogen-rich gas extracted from the pressure tower (11) that is fed to the additional air is supplied to the main heat exchanger (4) on the cold side along with the additional air, subjected to expansion by the second turbine, supplied to the main heat exchanger (4) at the third intermediate temperature level, and extracted from the main heat exchanger (4) on the warm side.

6. The method according to claim 4, wherein a portion of the nitrogen-rich gas extracted from the pressure tower (11) and fed to the additional air is supplied separately from the additional air to the main heat exchanger (4) on the cold side, extracted from the main heat exchanger (4) on the warm side, and fed to the additional air at the second intermediate temperature level and before the second turbine expands.

7. The method according to claim 4, wherein the base pressure level is 16 bar to 24 bar, wherein the pressure level to which the additional air is compressed above the base pressure level is 27 bar to 50 bar, wherein the pressure tower operates in a pressure range of 4 bar to 7 bar, wherein the main heat exchanger (4) operates at a temperature level of 0°C to 50°C on the warm side and at a temperature level of -150°C to -177°C on the cold side, wherein the first intermediate temperature level is -120°C to -90°C, wherein the second intermediate temperature level is -20°C to 30°C, wherein the third intermediate temperature level is -110°C to -60°C, wherein the first turbine expansion is performed at a pressure level of 4 bar to 7 bar, and wherein the second turbine expansion is performed at a pressure level of 100 mbar to 500 mbar above atmospheric pressure.

8. The method of claim 4, wherein one or two booster compressors (5, 6) are used to compress the additional air to a pressure level higher than the baseline pressure level, wherein, The expander (7, 9) is used to drive either one of the superchargers or at least one of the two superchargers, the expander being used in the expansion of the first turbine and the expansion of the second turbine.

9. The method according to any one of claims 1-3, wherein the tower system (10) further comprises a low-pressure tower (12) operating in a pressure range of 1 bar to 1.7 bar, and an argon extraction section (15) having at least one additional tower.

10. The method according to any one of claims 1-3, wherein the additional air, which is compressed to a pressure level higher than the base pressure level and is expanded and heated in the tower system (10) without separation, is compressed together with the air fed into the tower system (10) to a pressure level higher than the base pressure level.

11. The method of claim 10, wherein a first portion of the air to be fed into the tower system (10) and the air compressed together with the additional air to a pressure level above the base pressure level is cooled and fed into the tower system (10) without undergoing a first expansion and a second expansion, and a second portion is separated in liquefied form after the first expansion and fed into the tower system (10).

12. The method of claim 2, wherein the expansion of the additional air is performed in an expansion turbine.

13. An air separation device having a tower system (10) having a pressure tower (11), wherein the air separation device is adapted to: the pressure tower (11) operate in a pressure range of 4 bar to 7 bar; supplying air to the tower system (10) and separating it in the tower system (10), wherein, At least 90% of the air supplied to the tower system (10) is compressed to a base pressure level, which is more than 5 bar higher than the pressure range in which the pressure tower (11) operates; nitrogen-rich gas is extracted from the pressure tower (11); and more air is compressed to a pressure level above the base pressure level, expanded and heated in the tower system (10) without separation, at least in a first operating mode, characterized in that the air separation device is adapted to feed a portion of the nitrogen-rich gas extracted from the pressure tower (11) upstream of the expansion to the more air, at least in the first operating mode, and also to compress the more air to a pressure level above the base pressure level, expand and heat in the tower system (10) without separation, and not to feed the nitrogen-rich gas extracted from the pressure tower (11) to the more air in the second operating mode.

14. An air separation device having means for performing the features of the method in any one of claims 2 to 12.

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