CN117980678A

CN117980678A - Facility and method for cryogenic fractionation of air

Info

Publication number: CN117980678A
Application number: CN202280063916.4A
Authority: CN
Inventors: 斯特凡·洛克纳
Original assignee: Linde LLC
Current assignee: Messer LLC
Priority date: 2021-09-01
Filing date: 2022-08-26
Publication date: 2024-05-03
Also published as: CN117980679A; KR20240059622A; WO2023030683A1; WO2023030682A3; TW202316070A; KR20240057420A; TW202311683A; WO2023030682A2

Abstract

The invention relates to a plant (100) for the cryogenic fractionation of air, having: a rectification column system (10) comprising a higher pressure column (11), divided lower pressure columns (12, 13) and an argon column (14, 15); and a cold box system (20) comprising a first cold box (110), a second cold box (120) and a third cold box (130). The higher pressure column (11) is arranged below the lower section (12) of the lower pressure column (12, 13). The higher pressure column (11) is arranged in the first cold box (110) together with the lower part (12) of the lower pressure column (12, 13), and the top part (13) of the lower pressure column (12, 13) is arranged in the second cold box (120). It is proposed to arrange the argon column (14, 15) or one or more sections of the argon column (14, 15) in the third cold box (110, 120). A pure oxygen column (18) is disposed in the second cold box. The invention also provides a corresponding method.

Description

Facility and method for cryogenic fractionation of air

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

Prior Art

It is known to produce air products in liquid or gaseous form by cryogenic separation of air in an air separation plant and is described, for example, in h. -W.(Editions), industrial Gases Processing, wiley-VCH,2006, in particular section 2.2.5, "Cryogenic Rectification".

The air separation plant has rectification column systems which can be designed as double column systems, in particular as classical Linde double column systems, but also as triple column systems or multi-column systems. In addition to the rectification column for obtaining nitrogen and/or oxygen in liquid and/or gaseous state, i.e. for nitrogen/oxygen separation, a rectification column for obtaining further air components, in particular argon, may be provided.

The rectification columns in the rectification column system mentioned are operated at different pressure levels. Known double-column systems have so-called higher pressure columns (also called pressure columns, medium pressure columns or lower columns) and so-called lower pressure columns (also called upper columns). The higher pressure column is generally operated at a pressure of from 4 bar to 14 bar, in particular at about 5.3 bar or at about 11 bar. The low pressure column is generally operated at a pressure in the range of from 1 bar to 4 bar, in particular at about 1.4 bar, but may also be operated at 3 bar. In some cases, higher pressures may also be used in low pressure columns that may also operate at 2 bar to 4 bar and in pressure columns at 9 bar to 14 bar. The specific pressures cited here and below are the absolute pressures at the top of the rectification column indicated accordingly.

In known methods and facilities for cryogenic separation of air, an oxygen-rich, nitrogen-lean liquid is formed in a lower region of a higher pressure column and withdrawn from the higher pressure column. This liquid, which in particular also contains argon, is at least partly fed into the low-pressure column and is further separated in this low-pressure column. The liquid may be at least partially vaporized prior to feeding into the low pressure column, wherein optionally vaporized fraction and non-vaporized fraction may be fed into the low pressure column at different locations.

For argon extraction, an air separation plant with a crude argon column and a pure argon column may be used. One example is in(See above) in fig. 2.3A, and is described beginning at page 26, section "Rectification in the Low-pressure, crude and Pure Argon Column" and also beginning at page 29, section "Cryogenic Production of Pure Argon". As explained there, argon accumulates at a certain height in the low pressure column in the corresponding facility. At this point, or at another advantageous point optionally also below the argon maximum, argon-rich gas having an argon concentration of typically 5 to 15 mole% can be withdrawn from the low pressure column and transferred into the crude argon column. The corresponding gas typically contains about 0.05ppm to 100ppm nitrogen and is additionally substantially oxygen. It should be expressly emphasized that the indicated values for the gas withdrawn from the lower pressure column represent only typical exemplary values.

The crude argon column is essentially used to separate oxygen from the gas withdrawn from the lower pressure column. The oxygen separated in the crude argon column or the corresponding oxygen-enriched fluid may be returned to the low pressure column in liquid form. Oxygen or oxygen-enriched fluid is typically fed to several theoretical or actual trays of the lower pressure column below the feed point of the oxygen-enriched, nitrogen-depleted and optionally at least partially vaporized liquid withdrawn from the higher pressure column. The gaseous fraction which is maintained in the crude argon column during separation and which substantially contains argon and nitrogen is further separated in a pure argon column to obtain pure argon. The crude and pure argon columns have top condensers which may be cooled, in particular, with a portion of the oxygen-rich, nitrogen-lean liquid withdrawn from the higher pressure column, which portion is partially vaporized during this cooling. Other fluids may also be used for cooling.

In principle, pure argon columns can also be dispensed with in the corresponding installation, wherein in this case it is generally ensured that the nitrogen content at the argon transition is below 1ppm. However, this is not a mandatory prerequisite. In this case the same mass of argon as from a conventional pure argon column is generally withdrawn slightly more downwardly from the crude argon column or a similar column than the fluid conventionally transferred into the pure argon column, wherein the plate in the section between the crude argon condenser (i.e. the top condenser of the crude argon column) and the corresponding withdrawal in particular acts as a barrier plate for nitrogen. The present invention may be used with such an arrangement without a pure argon column. Since the crude argon column or similar column in such an arrangement is already used for pure argon production and not for crude argon production, it is also referred to as "argon column" in the following. Thus, the argon column may be a conventional crude argon column (with or without use with a pure argon column) or a corresponding crude argon column modified for pure argon production.

In order to improve the constructional height of the corresponding air separation plant and its pre-processing, EP 2 965 029 B1 proposes to divide the low pressure column into a base section (part) and a top section (top section), wherein the base section of the low pressure column is kept installed together with the high pressure column as in a conventional double column arrangement, but the top section of the low pressure column is stored in a separate cold box. Furthermore, it is proposed here to divide the crude argon column into a base section (base section) and a top section (top section) and to accommodate these sections in separate co-tanks. Liquid from the lower region of the top section of the low pressure column and the lower region of the base section of the crude argon column is returned to the base section of the low pressure column by means of a common pump.

The object of the present invention is to further improve the corresponding arrangement, in particular in terms of construction effort and costs.

Disclosure of Invention

Against this background, the present invention proposes a plant and a method for cryogenic separation of air having the features of the independent claims. Preferred embodiments form the subject matter of the dependent claims and the following description.

Before explaining the features and advantages of the present invention, some of the principles of the present invention will be explained in more detail, and terms used below will be defined.

Devices for use in air separation plants are described in the cited technical literature, for example in(See above) in section 2.2.5.6, "Apparatus". Unless defined differently below, the technical literature cited is therefore expressly referenced with respect to terms used within the framework of the present application.

In the terms used herein, liquids and gases may be enriched or absent of one or more components, where "enriched" may refer to a content of at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% on a molar, weight or volume basis, and "absent" may refer to a content of up to 25%, 10%, 5%, 1%, 0.1% or 0.01%. The term "primary" may correspond to the definition of "rich". The liquid and gas may also be enriched or depleted in one or more components, wherein these terms refer to the content of the initial liquid or initial gas from which the liquid or gas was extracted. A liquid or gas is "enriched" if it contains at least 1.1-fold, 1.5-fold, 2-fold, 5-fold, 10-fold, 100-fold or 1000-fold content, and "depleted" if it contains up to 0.9-fold, 0.5-fold, 0.1-fold, 0.01-fold or 0.001-fold content, based on the initial liquid or gas. If "oxygen", "nitrogen" or "argon" is referred to herein by way of example, this is also understood to mean an oxygen or nitrogen-rich liquid or gas, but does not necessarily consist exclusively of oxygen or nitrogen. With the facility according to the embodiment of the present invention, for example, a purity in the range of 0.05ppb oxygen in nitrogen, 0.2ppb oxygen in argon, and 0.2ppb argon in oxygen can be achieved.

The term "pressure range" and "temperature range" are used herein to characterize pressure and temperature, which means that the corresponding pressure and temperature in the corresponding facility need not be used in the form of an exact pressure value or temperature value in order to implement the inventive concept. However, such pressures and temperatures generally fall within certain ranges, such as about ±1%, 5% or 10% of the average value. In this case, the corresponding pressure range and temperature range may be in a discontinuous range or in a range overlapping each other. Specifically, the pressure range includes, for example, unavoidable or expected pressure losses. The same applies to the temperature range. The value indicated in bar, which refers to the pressure range, is the absolute pressure.

"Condenser evaporator" refers to a heat exchanger in which a first condensing fluid stream is indirectly heat exchanged with a second evaporating fluid stream. Each condenser evaporator has a liquefaction chamber and an evaporation chamber. The liquefaction chamber and the evaporation chamber have a liquefaction channel or an evaporation channel. Condensation (liquefaction) of the first fluid stream is performed in the liquefaction chamber, while evaporation of the second fluid stream is performed in the evaporation chamber. The evaporation chamber and the condensation chamber are formed by groupings of channels in heat exchange relationship with each other. The so-called main condenser is a condenser evaporator via which a higher-pressure column and a lower-pressure column of a facility for low-temperature separation of air are coupled to each other in a heat-exchanging manner.

The term "subcooling heat exchanger" is intended herein to mean a heat exchanger in which subcooling is performed on one or more material streams that are transferred between the columns of a rectifying column system of the type used herein. In its countercurrent flow, in particular the material stream or streams discharged from the rectification column system and the entire installation can be heated. In addition to the so-called main heat exchanger, there is also a supercooling heat exchanger which is characterized in that at least a major part of the air supplied to the rectification column system is cooled therein. The air separation plant according to the invention can in principle also be designed without a supercooling heat exchanger.

The term "cold box" is understood here to mean a temperature-insulated housing in which process engineering equipment operating at low temperatures, in particular cryogenic temperatures, is installed. The facility for cryogenic separation of air may comprise one or more corresponding cold boxes, and in particular may be produced in a modular manner from corresponding cold boxes, as is the case within the scope of the invention. In the cold box, several facility parts (i.e. for example separation equipment such as towers and associated heat exchangers) may also be fastened together with the pipes to a supporting steel frame, which is covered on the outside with sheet metal plates. The interior of the housing formed in this way is filled with an insulating material such as perlite in order to prevent heat input from the environment. It is also possible to pre-machine the cold boxes, partially or completely, at the factory with corresponding equipment, so that these must be done at the construction site or connected to each other only when needed. For the connection, a wire module that is temperature-insulated and possibly accommodated in a cold box can be used. In a typical cold box, the facility parts are usually installed at a minimum distance from the wall in order to ensure adequate insulation. The pipes in the cold box are preferably designed without flange connections, i.e. are welded completely, or with suitable transition parts according to the invention in order to avoid the formation of leaks. Due to the temperature differences that occur, there may be expansion bends in the pipe. The maintenance-prone components are generally not arranged in the cold box, so that the interior of the cold box is advantageously maintenance-free. The valve may be designed, for example, as a so-called "angle valve" in order to enable maintenance from the outside. In this case, the valve is located in the cold box wall; the line is led to the valve and back again. The lines and equipment are made of aluminum or stainless steel (particularly but not exclusively stainless steel) at very high operating pressures. The transition piece according to the invention makes it possible to connect such materials. The paint of the cold box is white in many times, but can also be other bright colors. Penetration of moisture from the ambient air (which will freeze at the cold plant parts) can be prevented, for example, by continuously flushing the cold box with, for example, nitrogen.

The relative spatial terms "upper," "lower," "above," "below," "adjacent," "proximate," "vertical," "horizontal," and the like refer herein to the spatial orientation of a rectification column or other components of an air separation plant under normal operation. The two components being arranged "one above the other" is understood here to mean that the upper end of the lower of the two components is located at a lower geodetic height than the lower end of the higher of the two components or at the same geodetic height as the lower end, and that the projections of the two equipment parts overlap in the horizontal plane. In particular, the two parts are arranged one entirely above the other, that is to say the axes of the two parts extend on the same vertical straight line. However, the axes of the two parts do not have to lie entirely vertically above one another, but can also be offset relative to one another, in particular in the case of one of the two parts (for example a rectifying column or column part with a smaller diameter) having the same distance from the sheet metal jacket of the cold box as the other part with a larger diameter. Terms such as "functionally below … …" or "functionally above … …" refer to the arrangement of partial columns in the case of a rectification column designed in multiple parts, which would have in the case of a rectification column formed in one piece.

Advantages of the invention

The invention relates to a facility for the cryogenic separation of air, comprising a rectification column system having a higher pressure column, a lower pressure column and an argon column, wherein the lower pressure column and optionally also the argon column are (each) divided into at least a base section and a top section, as described, for example, in the cited EP 2 965029b 1. Furthermore, the plant optionally has a pure oxygen column.

The pure oxygen column, if present, is used to obtain high purity or ultra high purity oxygen, with the residual content of extraneous components typically being as much as 0.05ppb or 1ppb methane, argon, krypton, xenon, nitrogen, hydrogen, carbon monoxide, carbon dioxide, etc., but optionally more or less. If present, the pure oxygen column is fed with liquid from an intermediate point of the argon column, which liquid is introduced at the top of the pure oxygen column. In the optionally present two-section argon column, the intermediate point is located in particular in the base section of the argon column and in any case above in particular the lowermost separation section for separating components with a boiling point higher than oxygen, in particular hydrocarbons, carbon dioxide, krypton and xenon.

The argon column may in particular be a crude argon column used in addition to a pure argon column. Instead of a crude argon column and a pure argon column, a single column for obtaining argon product combines the functions of the original argon column and the pure argon column partially with each other by providing additional sections for separating out nitrogen. If an argon column is mentioned later, this argon column may in particular be a crude argon column which is present in addition to the pure argon column, but also a correspondingly modified crude argon column, beside which no pure argon column is present.

For clarity, only the transfer of fluids between these columns and part of the columns used according to the invention is summarized below. The sump fluid of the pressure column is thus fed into the top section of the low pressure column, optionally after being used as cooling medium in the top condenser of the argon column and optionally the pure argon column (if present). The top gas of the pressure column is condensed into parts in a main condenser that connects the base sections of the pressure column and the lower pressure column while exchanging heat, and is recycled to the pressure column and discharged as product from the air separation plant. The sump liquid of the base section of the low pressure column is at least partially discharged as product from the air separation plant. The top gas of the base section of the low pressure column is fed into the top section of the low pressure column, in particular below the lowermost rectification section. The further top gas of the base section of the low-pressure column is fed into the argon column, in particular below the lowermost rectification section, or into the base section of the argon column, if this is correspondingly subdivided. The top gas of the base section of the argon column is fed into the top section of the argon column, in particular below the lowermost rectification section, with the argon column being correspondingly divided. The sump liquid from the top section of the argon column is fed into the base section of the argon column, in particular above the uppermost rectification section, with the argon column being correspondingly subdivided, pumps being used in particular for this purpose.

The terms "base section" and "top section" denote in each case sections of the column which are correspondingly divided and thus are designed in two sections which correspond in their function, in particular for the fractions or streams produced there, to the lower section or to the upper section of a conventional one-section column. The base section has, for example, a sump tank, and the top section has, for example, a top condenser. Thus, the top section is the section of the column that is connected to the corresponding condenser and in which the return stream is fed to the corresponding column. In the low pressure column of known air separation plants, which are designed in one piece, an oxygen-rich liquid fraction is obtained in the sump, which can be withdrawn as oxygen product. This is therefore also performed in the sump or lower region of the base section of the low-pressure column designed in two sections. The gaseous nitrogen product or so-called impure nitrogen can thus be withdrawn at the top of a low pressure column which is a section of the known air separation plant, provided that it is equipped accordingly. The same applies to the upper region of the top section of the low-pressure column designed in two sections. At the top of the single section Duan Yada (with respect to the term "argon column", see explanation above), and thus at the upper region of the top section of the two-section argon column, a crude argon stream or argon product stream is withdrawn from the sump of the single-section argon column, and correspondingly from the lower region of the base section of the two-section argon column, feeding the resulting sump product back into the low pressure column.

In the context of the present invention, the division of the low pressure column into a top section and a base section is performed in particular above the so-called oxygen section. As inAs illustrated in reference to fig. 2.4A (supra), although argon is contained in atmospheric air at a level of less than 1 mole percent, it has a strong effect on the concentration profile in the low pressure column. The separation in the lowermost rectification section of the low pressure column, which typically comprises 30 to 80 theoretical or actual trays, can thus be regarded as a substantially binary separation between oxygen and argon. The rectification section is the oxygen section mentioned. The separation is changed to a ternary separation of nitrogen, oxygen and argon within several theoretical or actual trays, starting only at the discharge point of the gas transferred into the crude argon column or in the division performed according to the invention above the oxygen section.

The term "rectification section" shall here denote any section within a rectification column or a partial column of a multi-section rectification column which is provided to perform rectification and which is specifically designed for this purpose with a corresponding mass transfer structure, such as a separation plate or an ordered or disordered packing. In particular, a fluid outlet or inlet (e.g., a side outlet) may be provided between the rectification sections. Below the (functionally) lowest rectification zone, the "base" of the rectification column is located above the (functionally) upper rectification zone, i.e. the "top" of this upper rectification zone.

The present invention generally proposes a facility for cryogenic separation of air having a rectification column system having a higher pressure column, a lower pressure column and an argon column; and a cold box system having a first cold box, a second cold box, and a third cold box. Further cold boxes are possible, for example a total of four cold boxes, wherein the low pressure column is divided into at least a base section and a top section and a main heat exchanger box may additionally be provided.

In the context of the present invention, the base section and the top section of the low pressure column are arranged side by side in such a way that the orthogonal projection of the base section of the low pressure column on the horizontal plane does not intersect the orthogonal projection of the top section of the low pressure column on the horizontal plane. In particular, there is a cross-sectional plane intersecting the base section and the top section of the low pressure column.

Optionally, in the context of the present invention, the argon column may likewise be divided into at least a base section and a top section, wherein the base section and the top section of the argon column are arranged side by side in such a way that the orthogonal projection of the base section of the argon column onto the mentioned horizontal plane does not overlap with the orthogonal projection of the top section of the argon column onto the horizontal plane. In particular, there is a cross-sectional plane intersecting the base section and the top section of the low pressure column.

In contrast, in the context of the present invention, the high pressure column is arranged below the base section of the low pressure column such that the orthogonal projection of the high pressure column on the horizontal plane overlaps with the orthogonal projection of the base section of the low pressure column on the horizontal plane, wherein the longitudinal axes of the high pressure column and the base section of the low pressure column lie in particular along a common main axis, or there is a vertical axis intersecting the base sections of the high pressure column and the low pressure column.

In the context of the present invention, the higher pressure column is arranged in a first cold box together with the base section of the lower pressure column, and the top section of the lower pressure column is arranged in a second cold box. According to the invention, the argon column or one or more sections of the argon column are in the first cold box and/or the second cold box. Alternatively, the argon column or all sections of the argon column are accommodated in a third cold box. As a further alternative, there are separate tanks for the base section and the top section of the argon column.

The arrangement proposed according to the invention results in particular in a simple constructability and small transport dimensions and enables as low a tank height as possible (not higher than the church tower or the vicinity … … of the airport). "Cold plant parts" are understood here to mean equipment or equipment parts which are operated at low temperatures (in particular below-50 ℃) during normal operation of the plant.

In one embodiment of the invention, wherein a correspondingly subdivided argon column is provided, the base section of the argon column can be arranged in particular in the first cold box and the top section of the argon column can be arranged in particular in the second cold box, or vice versa, i.e. the base section of the argon column can also be arranged in the second cold box and the top section of the argon column can also be arranged in the first cold box.

As mentioned, the argon column may be designed as a crude argon column, in which case in particular a pure argon column may be provided. The pure argon column can be arranged in the first or second cold box, in particular in the case of the corresponding embodiment or subdivision, in the cold box in which the top section of the argon column designed as a crude argon column is arranged.

In the present invention, the pure oxygen column is arranged in one of these cold boxes, i.e. in the same cold box as the argon column or the first section of the argon column.

The pure oxygen column and the argon column or the first section of the argon column (e.g. the base section) are arranged side by side in the installation used according to the invention such that the orthogonal projection of the pure oxygen column or the upper section of the pure oxygen column on the horizontal plane does not intersect the orthogonal projection of the argon column or the first section on the horizontal plane. The upper section may be part of a pure oxygen column that is not occupied by a sump evaporator disposed in a sump of the pure oxygen column. Due to the size of the sump evaporator, the sump evaporator may also exhibit a significantly larger cross-sectional space compared to the upper section of the pure oxygen column, and may optionally be arranged off-center (relative to the central axis of the upper section). In this case, the orthogonal projection of the lower section of the pure oxygen column with the sump evaporator on the horizontal plane may also partially overlap with the orthogonal projection of the base section of the argon column on the horizontal plane.

Furthermore, the top section of the low-pressure column and the pure oxygen column or the upper section of the pure oxygen column are preferably arranged side by side in such a way that the orthogonal projection of at least the pure oxygen column or the upper section of the pure oxygen column on the horizontal plane does not overlap with the orthogonal projection of the top section of the low-pressure column or the first section of the argon column on the horizontal plane.

In other words, as already stated, if a pure oxygen column is present in the corresponding embodiment, the pure oxygen column is fed with a first transfer liquid at the feed point, which is removed from the argon column or the base section of the argon column at the extraction point. The cited tower or tower section is thus equipped with corresponding extraction points and feed points. As mentioned, the extraction point from the argon column or the base section of the argon column is located in particular above the rectification section for discharging hydrocarbons. The extraction point for the first transfer liquid is in particular located 1 to 30 theoretical plates above the sump of the argon column or the base section of the argon column.

Thus, the first transfer liquid transferred into the pure oxygen column has in particular an oxygen content of 50 to 95 mol%, an argon content of 10 to 50%, a nitrogen content of 0.1 to 500ppm, preferably 0.1 to 100ppm and a content of 0.01ppb to 25ppm of other components having a higher boiling point than oxygen.

The pure oxygen column and the argon column or the base section of the argon column are advantageously arranged in such a way that the extraction point for the transfer liquid from the argon column or the base section of the argon column is geodetically located above the feed point for the transfer liquid into the pure oxygen column. In this way, the transfer liquid can flow into the pure oxygen column, in particular without using a pump, which saves on the one hand the effort of the corresponding pump and on the other hand possible contamination by the corresponding pump. The feed point of the transfer fluid into the pure oxygen column is in particular located above the uppermost rectification section of the pure oxygen column.

In one embodiment of the invention with a correspondingly divided argon column, it is provided in particular that the base section of the argon column is fed with a second transfer liquid at a feed point which is located in particular below the lowermost rectification section in the base section of the argon column, which transfer liquid is taken from the top section of the low pressure column at an extraction point which is located in particular below the lowermost rectification section in the top section of the low pressure column. The cited tower or tower section is thus equipped with corresponding extraction points and feed points.

In this embodiment, the top section of the low pressure column and the base section of the argon column may be arranged in such a way that the extraction point for the second transfer liquid from the top section of the low pressure column is geodetically located above the feed point for the further transfer liquid into the base section of the argon column. In this way, the sump liquid from the base section of the low pressure column and the sump liquid from the top section can be combined in the base section of the argon column and fed back to the base section of the low pressure column using only one (i.e., using a common) pump, which in the ideal case has a redundant design.

Preferably, the evacuation section is arranged in or is a base section of the argon column. The evacuation section is located inside the shell of the tower and extends over a vertical subregion of the tower. No mass transfer element is present in the evacuation section, so that the evacuation section does not affect mass transfer. First, as the column shell becomes more expensive, providing such sections appears to be counterproductive. However, in the context of exchanging one or more transfer fluids, it is operationally advantageous in the present invention to place the mass transfer area of the top section of the low pressure column relatively high (above the evacuation section) and the sump relatively low (below the evacuation section). In particular, the evacuation section is arranged in a lower region of the tower, in particular directly above the lower end of the tower shell.

If the corresponding system has a subcooling heat exchanger, the subcooling heat exchanger may be arranged in one of the cold boxes. In the embodiment just explained, the subcooling heat exchanger may be arranged in particular below the top section of the lower pressure column.

In this embodiment of the invention, it is thus provided in particular that the top section of the low-pressure column is arranged geodetically above the supercooling heat exchanger. If the sump liquid of the top section of the low pressure column can drain from above the corresponding rectification section into the sump from the base section of the argon column and into the pure oxygen column, the sump liquid must be located sufficiently high. In this case, the sump of the base section of the argon column may extend downward by a so-called "blank zone" (i.e., an empty zone or empty section) so that it may be ensured at the same time that liquid may drain from the top section of the low pressure column into the sump of the base section of the argon column in the corresponding embodiment. Thus, the low-pressure column can be arranged as low as possible, and the box height of the cold box in which the low-pressure column is located can be reduced.

As an alternative to the just mentioned embodiment, it may also be provided that the top section of the low pressure column is fed with a second transfer liquid at a feed point, in particular below the lowermost rectification section in the top section of the low pressure column, which is removed from the base section of the argon column at an extraction point, in particular below the lowermost rectification section in the base section of the argon column. The cited tower or tower section is thus equipped with corresponding extraction points and feed points. In this embodiment, the base section of the argon column and the top section of the low pressure column are arranged such that the extraction point for the further transfer liquid from the base section of the argon column is geodetically located above the feed point for the further transfer liquid into the top section of the low pressure column. In this way, the sump liquid in the low pressure column and the sump liquid of the base section of the argon column may be combined in the top section of the low pressure column and returned to the base section of the low pressure column by means of only one pump.

In a corresponding system with a subcooling heat exchanger, in the embodiment just explained, the heat exchanger may be arranged in particular below the base section of the argon column.

It may in particular be provided that the top section of the low pressure column and the top section of the argon column are arranged side by side in such a way that the orthogonal projection of the top section of the low pressure column on the horizontal plane H does not overlap with the orthogonal projection of the top section of the argon column on the horizontal plane. There is correspondingly a cross-sectional plane intersecting the top section of the low pressure column and the top section of the argon column.

In the context of the present invention, in particular, a cold box height of 35 meters to 50 meters, in particular about 43 meters, may be maintained. The higher pressure column may in particular have a height of 15 to 30 meters, in particular 25.8 meters, and the base section of the lower pressure column may in particular have a height of 7 to 20 meters (e.g. 14.8 meters). The height of the base section of the low pressure column is in particular defined by the height of the main condenser and the separation device accommodated therein and the so-called oxygen section, which may in particular be located at 5 to 14 meters (e.g. 7.4 meters). The diameter may in particular be 1.5 to 4 meters, for example about 2.8 meters. The base section of the argon column has a height of, for example, 25 to 45 meters, in particular about 39 meters.

The top section of the low pressure column specifically has a height of 18 to 30 meters (e.g., 23 meters) with a diameter of 2.4 to 3 meters, such as about 2.6 meters, or a height of 25 to 30 meters (e.g., about 27 meters) with a diameter of 1.2 to 4.0 meters, such as about 2.45 meters. These dimensions depend in particular on the filler density utilized. The top section of the argon column may have advantageous dimensions.

The proposed arrangement according to the invention and its embodiments enable a compact design specifically for this background.

As in the known system, the base section of the low-pressure column is connected to the high-pressure column via a condenser evaporator for mutual heat exchange, and the base section of the low-pressure column and the high-pressure column are in particular arranged in the form of known Linde double columns in a common column shell or in several column shells connected by shells (but without the top section of the low-pressure column).

If the subcooling heat exchanger is installed upright, the subcooling heat exchanger may specifically have a vertical space requirement of up to 45 meters (e.g., about 8 meters). If the top section of the argon column includes a corresponding top condenser (crude argon condenser), the top section, like the base section of the argon column, typically has a height of 30m to 40 m. The above explained arrangement variants for supercooling heat exchangers are particularly advantageous, since these variants are associated with space-saving arrangements. Other arrangement variants of supercooling heat exchangers, for example in heat exchanger tanks and the like, may also be advantageous.

(A) The pure oxygen column may be arranged in the first cold box close to the base sections of the high pressure column, the low pressure column and the argon column (if with corresponding subdivision) such that the orthogonal projection of at least the upper section of the pure oxygen column (for reasons and for further explanation, see above) on the horizontal plane does not overlap with the orthogonal projection of the high pressure column on the horizontal plane and the orthogonal projection of the base section of the low pressure column on the horizontal plane and the orthogonal projection of the base section of the argon column. The connecting lines are thereby minimized.

If the arrangement (A) is no longer capable of delivery due to its size, the HDS can be repositioned with the lower section of the LDS into a separate bin. Desirably, the upper section of the low pressure column is then located in a second cold box with the argon column. The reboiler of the pure oxygen column may be located in the shadow of the low pressure column and arranged asymmetrically. An argon column or section thereof is disposed in the third cold box. The height arrangement is important here.

In the context of the present invention, the base section of the argon column (with its corresponding subdivision) may in particular be provided for separating high boiling components and also other impurities, in particular also to avoid enrichment.

In the context of the present invention, in particular, a lower region of the top section of the low pressure column and a lower region of the base section of the argon column (if with corresponding divisions) may be fluidly coupled to an upper region of the base section of the low pressure column via a pump.

For the sake of clarity only, it should be mentioned here again that the plant proposed according to the invention advantageously has means configured to feed the high-pressure column with cooling compressed air, means configured to feed the low-pressure column with fluid from the high-pressure column and means configured to feed the argon column with fluid from the low-pressure column.

Finally, the invention also extends to a process for the cryogenic separation of air; for its features, reference is explicitly made to the corresponding independent patent claim. In particular, the facility is used in such a method as has been explained previously in the different embodiments. For the features and advantages of the proposed method and of the possible embodiments, reference is therefore explicitly made to the explanation relating to the installation according to the invention.

The invention is explained in more detail below with reference to the drawings, which illustrate embodiments of the invention and embodiments not according to the invention.

Drawings

FIG. 1 illustrates, in simplified process flow diagram form, a facility for cryogenic separation of air that may be based on embodiments of the present invention.

Fig. 2 illustrates in side view and in simplified representation the arrangement of components of a facility designed for cryogenic separation of air according to an embodiment of the invention.

Fig. 3 illustrates in plan view and in simplified representation the arrangement of components of a facility designed for cryogenic separation of air according to an embodiment of the invention.

Fig. 4 shows a modification of fig. 2, in which an evacuation section is used.

If the facility components of a facility for cryogenic separation of air (also referred to below as "air separation facility") are described below, the corresponding explanations also apply to the method thus performed, and vice versa.

Embodiments of the invention

Fig. 1 schematically illustrates an air separation plant configured to obtain an argon product and a pure oxygen product, and generally indicated at 100.

The air separation plant 100 has a rectification column system 10 comprising a high pressure column 11, a low pressure column divided into a base section 12 and a top section 13, a (crude) argon column also divided into a base section 14 and a top section 15, and a pure argon column 20. The pure oxygen column is indicated by 18. The box denoted 1 comprises customary components for compression, purification and cooling of feed air, in particular also main heat exchangers of known type, which are present in the illustrated type of air separation plant. The supercooling heat exchanger is indicated with 17.

The base section 12 and the top section 13 of the low pressure column and the base section 14 and the top section 15 of the argon column are structurally separate from each other and are arranged close to each other in the meaning explained above. Together, the base section 12 and the top section 13 of the low pressure column functionally correspond to a conventional low pressure column of a double column. The base section 12 and the top section 13 of the higher pressure column 11 as well as of the lower pressure column thus form a rectification column system for nitrogen-oxygen separation of a type known per se, to which an argon system consisting of the base section 14 and the top section 15 of the argon column and the pure argon column 20 is connected.

In the exemplary embodiment shown, the cooled and compressed feed air is fed in the form of two material streams a, b into the top section 13 of the higher pressure column 11 or the lower pressure column. The air separation plant 100 may be designed for internal compression and may be designed into the framework shown herein as desired. The additionally compressed feed air is conducted in the form of a material stream c through a sump evaporator of the pure oxygen column 18, not separately designated, where it is at least partially condensed and then fed into the top section 13 of the low pressure column as such (now referred to as d). The particular type of air fed into the column arrangement is not critical to the invention and can be designed in any desired manner (with/without choking, with/without air fed into the low pressure column or the top section 13 of the low pressure column, etc.). This also applies to supplying turbines for cold power generation, which may or may not be provided.

The higher-pressure column 11 and the base section 12 of the lower-pressure column are connected for heat exchange via a condenser evaporator 19 (so-called main condenser) and are designed as a structural unit. However, the invention is in principle also applicable to systems in which the higher pressure column 11 and the lower pressure column (or the base section 12 thereof) are arranged separately from each other and have a separate condenser evaporator 19, i.e. are not integrated into the column.

The operation of the air separation plant 100 is directly apparent from the representation according to fig. 1. Reference is therefore made to the technical literature cited at the outset.

In particular, the base section 12 and the top section 13 of the low-pressure column are in this case fluidly coupled to each other, since the top gas is transferred from the upper region of the base section 12 of the low-pressure column to the lower region of the top section 13 of the low-pressure column in the form of a material flow e. As also explained with reference to fig. 2, the arrangement of the top section 13 of the low pressure column and the base section 14 of the argon column is in the example shown such that sump liquid in the form of a material flow f can flow from the lower region of the top section 13 of the low pressure column into the lower region of the base section 14 of the argon column, wherein a further section of the top gas is also fed from the upper region of the base section 12 of the low pressure column in the form of a material flow g. In this way, sump liquid is collected in the sump of the base section 14 of the argon column from the top section 13 of the low pressure column and the base section 14 of the argon column, and can be pumped back into the upper region of the base section 12 of the low pressure column in the form of a material stream h by means of a common pump 110. As mentioned, the opposite arrangement is also possible.

The top gas of the base section 14 of the argon column is transferred into the lower region of the top section 15 of the argon column and liquid is pumped back with pump 120 accordingly. The incorporation of the pure argon column 20 may correspond substantially to the incorporation routine in the art. The argon column consisting of base section 14 and top section 15 is thus fluidly connected in parallel to the low pressure column or base section 12 and top section 13 of the low pressure column such that the corresponding top gas from the upper region of the base section 12 of the low pressure column is also transferred into the lower region of the base section 14 of the argon column and sump liquid is returned from the lower region of the base section 14 of the argon column into the upper region of the base section 12 of the low pressure column. In particular, the same pump is used, which is also used to return sump liquid from the lower region of the top section 13 of the low pressure column into the upper region of the base section 12 of the low pressure column.

Furthermore, the base section 14 and the top section 15 of the argon column are fluidly coupled to each other, because the top gas is transferred from the upper region of the base section 14 of the argon column into the lower region of the top section 15 of the argon column, and the sump liquid is recycled from the lower region of the top section 15 of the argon column into the upper region of the base section 14 of the argon column by means of a (further) pump.

The pure oxygen column 18 is fed here at a feed point 18a with a transfer liquid in the form of a material flow t, which is removed from the base section 14 of the argon column at an extraction point 14 a. The pure oxygen column 18 and the base section 14 of the argon column are arranged in such a way that the extraction point 14a for the transfer liquid from the base section 14 of the argon column is located geodetically above the feed point 18a for the transfer liquid into the pure oxygen column 18, as a result of which the transfer liquid can be transferred into the pure oxygen column 18 without a pump.

The base section 14 of the argon column is furthermore fed with a further transfer liquid in the form of the already mentioned material stream f at a feed point 14b, which is removed from the top section 13 of the low-pressure column at an extraction point 13b, wherein the top section 13 of the low-pressure column and the base section 14 of the argon column are arranged in the example illustrated here in such a way that the extraction point 13b for the further transfer liquid from the top section 13 of the low-pressure column is located above the feed point 14b for the further transfer liquid into the base section 14 of the argon column.

The integration of the components of the air separation plant 100 into the cold box is illustrated in simplified side view in fig. 2, wherein the components of the air separation plant 100 are indicated with the same reference numerals as explained above with respect to fig. 1. As shown in fig. 1, these components are shown in a side view, but are more simplified. The fluid connection is not shown but is obvious in correspondence with the representation according to fig. 1. Two cold boxes 110 and 120 are illustrated, which as explained below contain and thermally insulate the components of the air separation plant 100.

The base section 12 and the top section 13 of the low-pressure column are in this case arranged close to each other in such a way that the orthogonal projection of the base section 12 of the low-pressure column onto the horizontal plane H does not overlap with the orthogonal projection of the top section 13 of the low-pressure column onto the horizontal plane H, and the base section 14 and the top section 15 of the argon column are likewise arranged side by side in such a way that the orthogonal projection of the base section 14 of the argon column onto the horizontal plane H does not overlap with the orthogonal projection of the top section 15 of the argon column onto the horizontal plane H.

In contrast, the higher pressure tower 11 is arranged below the base section 12 of the lower pressure tower such that the orthogonal projection of the higher pressure tower 11 on the horizontal plane H overlaps with the orthogonal projection of the base section 12 of the lower pressure tower on the horizontal plane H.

The pure oxygen column 18 and the base section 14 of the argon column are arranged side by side, such that the orthogonal projection of at least one upper section of the pure oxygen column 18 (explained further above) on the horizontal plane H does not overlap with the orthogonal projection of the base section 14 of the argon column on the horizontal plane H,

Furthermore, in the air separation plant 100, the top section 13 of the low pressure column and the top section 15 of the argon column are arranged side by side in such a way that the orthogonal projection of the top section 13 of the low pressure column on the horizontal plane H overlaps with the orthogonal projection of the top section 15 of the argon column on the horizontal plane H.

The high pressure column 11, the base section 12 of the low pressure column and the base section 14 of the argon column as well as the pure oxygen column 18 are arranged in a first cold box 110, and the top section 13 of the low pressure column and the top section 15 of the argon column are arranged just like the pure argon column 20 in a second cold box 120. This results in the advantages of the corresponding embodiments according to the invention.

As illustrated here in dashed lines, the supercooling heat exchanger 17 may be arranged in the second cooling tank 120 in particular below the top section 13 of the low-pressure column, such that the orthogonal projection of the supercooling heat exchanger 17 on the horizontal plane H in particular overlaps with the orthogonal projection of the top section 13 of the low-pressure column on this horizontal plane H.

As explained, the top section 13 of the low pressure column may be designed to have a lower packing density than the top section 15 of the argon column, and the base section 14 of the argon column may be configured to separate methane. As explained above and in detail in fig. 1, also here, the lower region of the top section 13 of the low pressure column and the lower region of the base section 14 of the argon column can be fluidly coupled to the upper region of the base section 12 of the low pressure column via a (common) pump.

Fig. 3 illustrates the components shown in fig. 2 in plan view, with the horizontal plane H parallel to the paper plane, and for further details reference is explicitly made to the explanation relating to fig. 2.

Fig. 4 corresponds to fig. 2, except for the evacuation section 14a of the base section 14 of the argon column. The column shell extends uninterrupted over the entire length of the column (i.e., including the evacuation section 14a shown in phantom). Only above the evacuation area 14a is a mass transfer element, such as structured packing, installed. Liquid drips from the lower end of the mass transfer element through the evacuation section into the column sump at the lower end of the evacuation section 14 a.

Claims

1. A facility (100) for cryogenic separation of air, having

-A rectifying column system (10) having a higher pressure column (11), a lower pressure column (12, 13), an argon column (14, 15) and a pure oxygen column (18); and a cold box system (20), wherein

-The pure oxygen column (18) and the argon column or the base section (14) of the argon column (14, 15) are arranged side by side such that the orthogonal projection of at least one upper section of the pure oxygen column (18) on a horizontal plane (H) does not overlap with the orthogonal projection of the argon column (14, 15) or the base section (14) of the argon column (14, 15) on the horizontal plane (H),

-The pure oxygen column (18) has a feed point (18 a) for a first transfer liquid and the argon column (14, 15) or the base section (14) of the argon column (14, 15) has an extraction point (14 a) for the first transfer liquid, wherein the pure oxygen column (18) and the base section of the argon column (14, 15) are arranged such that the extraction point (14 a) for the first transfer liquid is geodetically located above the feed point (18 a) for the first transfer liquid,

It is characterized in that

Said low pressure column (12, 13) being divided into at least a base section (12) and a top section (13),

-The base section (12) and the top section (13) of the low pressure column (12, 13) are arranged close to each other in such a way that the orthogonal projection of the base section (12) of the low pressure column (12, 13) on the horizontal plane (H) does not intersect the orthogonal projection of the top section (13) of the low pressure column (12, 13) on the horizontal plane (H),

-The high-pressure column (11) is arranged below the base section (12) of the low-pressure column (12, 13) in such a way that an orthogonal projection of the high-pressure column (11) on the horizontal plane (H) intersects the orthogonal projection of the base section (12) of the low-pressure column (12, 13) on the horizontal plane (H),

-The pure oxygen column (18) and the argon column (14, 15) or the base section (14) of the argon column (14, 15) are arranged side by side such that an orthogonal projection of at least one upper section of the pure oxygen column (18) on the horizontal plane (H) does not overlap with the orthogonal projection of the argon column (14, 15) or the base section (14) of the argon column (14, 15) on the horizontal plane (H),

The cold box system has a first cold box (110), a second cold box (120) and a third cold box (130),

-The higher pressure column (11) is arranged in the first cold box (110) together with the base section (12) of the lower pressure column (12, 13),

-Said top section (13) of said low pressure column (12, 13) being arranged in said second cold box (120),

-Said argon column (14, 15) or one or more sections of said argon column (14, 15) are arranged in said third cold box (130), and

-Said pure oxygen column (18) is arranged in said second cold box.

2. The plant (100) according to claim 1, wherein the argon column (14, 15) is divided into at least a base section (14) and a top section (15), wherein the base section (14) and the top section (15) of the argon column (14, 15) are arranged close to each other in such a way that an orthogonal projection of the base section (14) of the argon column (14, 15) on the horizontal plane (H) does not intersect an orthogonal projection of the top section (15) of the argon column (14, 15).

3. The plant (100) according to claim 1 or 2, wherein the argon column (14, 15) is designed as a crude argon column, and in addition a pure argon column (20) is provided, wherein the pure argon column (20) is arranged in the first cold box (110) or the second cold box (120), in particular in the cold box in which the top section (15) of the argon column (14, 15) designed as a crude argon column is arranged.

4. The plant (100) according to any one of the preceding claims, wherein the extraction point (14 a) for the first transfer liquid is located 1 to 30 theoretical plates above the sump of the base section of the argon column (14, 15).

5. The plant (100) according to any one of the preceding claims, wherein the base section (14) of the argon column (14, 15) has a feed point (14 b) for a second transfer liquid and the top section (13) of the low pressure column (12, 13) has an extraction point (13 b) for the second transfer liquid, wherein the top section (13) of the low pressure column (12, 13) and the base section (14) of the argon column (14, 15) are arranged such that the extraction point (13 b) for the second transfer liquid is located above the feed point (14 b) for the second transfer liquid.

6. The plant (100) according to any one of the preceding claims, wherein the evacuation section (13 a) of the argon column (14, 15) is the base section (14) of the argon column or is arranged in the base section.

7. The plant (100) according to claims 1 to 6, having: -a supercooling heat exchanger (17) arranged in the first cold box (110) or the second cold box (120), in particular below the top section (13) of the low-pressure column (12, 13) in the second cold box (120).

8. The plant (100) according to any one of the preceding claims, wherein the top section (13) of the low-pressure column (12, 13) has a feed point (13 c) for a second transfer liquid and the base section (14) of the argon column (14, 15) has an extraction point (14 c) for the second transfer liquid, wherein the base section (14) of the argon column (14, 15) and the top section (13) of the low-pressure column (12, 13) are arranged in such a way that the extraction point (14 c) for the second transfer liquid is located above the feed point (13 c) for the second transfer liquid.

9. The plant (100) according to claim 8, having: -a supercooling heat exchanger (17) arranged below the base section (14) of the argon column (14, 15).

10. The installation according to any one of the preceding claims, wherein all cold equipment parts are arranged in the first cold box (110) or the second cold box (120) and no third cold box is used.

11. The plant according to any one of the preceding claims, wherein the first section (14) of the crude argon column (14, 15) is formed by the base section of the crude argon column.

12. A method for cryogenic separation of air, wherein a plant (100) according to any one of claims 1 to 11 is used.