EP4396509A1 - Plant and process for low-temperature fractionation of air - Google Patents

Abstract

The invention relates to a plant (100) for low-temperature fractionation of air, having a rectification column system (10) comprising a high-pressure column (11), a divided low-pressure column (12, 13) and an argon column (14, 15), and a coldbox system (20) comprising a first coldbox (110), a second coldbox (120) and a third coldbox (130). The high-pressure column (11) is disposed beneath the lower portion (12) of the low-pressure column (12, 13). The high-pressure column (11) together with the lower portion (12) of the low-pressure column (12, 13) is disposed in the first coldbox (110), and the top portion (13) of the low-pressure column (12, 13) in the second coldbox (120). It is proposed that the argon column (14, 15) or one or more sections of the argon column (14, 15) be disposed in the third coldbox (110, 120). The pure oxygen column (18) is disposed in the second coldbox. The present invention likewise provides a corresponding process.

Description

Description

Plant and process for low-temperature separation of air

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

State of the art

The production of air products in a liquid or gaseous state by low-temperature separation of air in air separation plants is known and is described, for example, by H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH, 2006, in particular Section 2.2.5, "Cryogenic Rectification".

Air separation plants have rectification column systems which can be designed as two-column systems, in particular as classic Linde double-column systems, but also as three- or multi-column systems. In addition to the rectification columns for obtaining nitrogen and/or oxygen in the liquid and/or gaseous state, ie the rectification columns for nitrogen-oxygen separation, rectification columns for obtaining further air components, in particular argon, can be provided.

The rectification columns of the rectification column systems mentioned are operated at different pressure levels. Known double column systems have a so-called high-pressure column (also referred to as a pressure column, medium-pressure column or lower column) and a so-called low-pressure column (also referred to as an upper column). The high-pressure column is typically operated at a pressure in a pressure range from 4 to 14 bar, in particular at about 5.3 bar, or at about 11 bar. The low-pressure column is typically operated at a pressure in a pressure range from 1 to 4 bar, in particular at about 1.4 bar, but also at 3 bara. In certain cases, higher pressures can also be used in the low-pressure column; this can also be operated at 2-4 bara and the pressure column at 9-14 bara. At the specific pressures given here and below these are absolute pressures at the top of the rectification columns specified in each case.

In known processes and systems for the low-temperature separation of air, an oxygen-enriched and nitrogen-depleted liquid is formed in a lower region of the high-pressure column and drawn off from the high-pressure column. At least part of this liquid, which also contains argon, is fed into the low-pressure column and further separated there. It can be at least partially evaporated before it is fed into the low-pressure column, it being possible for evaporated and unevaporated fractions to be fed into the low-pressure column at different positions.

Air separation plants with crude and pure argon columns can be used to produce argon. An example is illustrated by Häring (see above) in Figure 2.3A and described from page 26 in the section "Rectification in the Low-pressure, Crude and Pure Argon Column" and from page 29 in the section "Cryogenic Production of Pure Argon". As explained there, argon accumulates in appropriate systems at a certain level in the low-pressure column. At this point or at another favorable point, possibly also below the argon maximum, argon-enriched gas with an argon concentration of typically 5 to 15 mole percent can be drawn off from the low-pressure column and transferred to the crude argon column. A corresponding gas typically contains about 0.05 to 100 ppm nitrogen and otherwise essentially oxygen. It should be expressly emphasized that the values given for the gas drawn off from the low-pressure column only represent typical example values.

The primary purpose of the crude argon column is to separate the oxygen from the gas drawn off from the low-pressure column. The oxygen separated off in the crude argon column or a corresponding oxygen-rich fluid can be returned in liquid form to the low-pressure column. The oxygen or the oxygen-rich fluid is typically fed into the low-pressure column several theoretical or practical trays below the feed point for the oxygen-enriched and nitrogen-depleted and possibly at least partially vaporized liquid withdrawn from the high-pressure column. A gaseous fraction remaining in the crude argon column during separation Essentially contains argon and nitrogen is further separated in the pure argon column to obtain pure argon. The crude and pure argon columns have top condensers, which can be cooled in particular with part of the oxygen-enriched and nitrogen-depleted liquid withdrawn from the high-pressure column, which partially evaporates during this cooling. Other fluids can also be used for cooling.

In principle, a pure argon column can also be dispensed with in corresponding systems, whereby it is typically ensured here that the nitrogen content at the argon transition is below 1 ppm. However, this is not a mandatory requirement. In this case, argon of the same quality as from a conventional pure argon column is withdrawn from the crude argon column or a comparable column, typically somewhat further below than the fluid conventionally transferred to the pure argon column, with the trays in the section between the crude argon condenser, i.e. the top condenser of the crude argon column, and an appropriate vent, in particular as barrier floors for nitrogen. The present invention can be used with such an arrangement without a pure argon column. Since the crude argon column or a comparable column in such an arrangement is already used for obtaining pure argon and not for obtaining crude argon, the term “argon column” is also used below. An argon column can thus be a conventional crude argon column (which is used with or without a pure argon column) or a corresponding crude argon column modified to obtain pure argon.

In order to improve the height of a corresponding air separation plant and its ability to be prefabricated, EP 2 965 029 B1 proposes dividing the low-pressure column into a foot part (foot section) and a top part (top section), with the foot part of the low-pressure column being connected to the high-pressure column as in a classic double-column arrangement remains installed, but the head part of the low-pressure column is relocated to a separate cold box. It is also proposed here to divide the crude argon column into a top part (top section) and a bottom part (bottom section) and to accommodate these sections in separate cold boxes. Liquid from a lower portion of the top of the low pressure column and a lower portion of the bottom of the crude argon column is returned to the base of the low-pressure column by means of a common pump.

The present invention sets itself the task of further improving corresponding arrangements, in particular with regard to the structural complexity and the costs.

Disclosure of Invention

Against this background, the present invention proposes a system and a method for the low-temperature separation of air with the features of the independent patent claims. Preferred configurations are the subject matter of the dependent claims and the following description.

Before the features and advantages of the present invention are explained, some basic principles of the present invention are explained in more detail and terms used in the following are defined.

The devices used in an air separation plant are described in the specialist literature cited, for example in Häring (see above) in Section 2.2.5.6, "Apparatus". Unless the following definitions deviate from this, reference is therefore expressly made to the technical literature cited for the language used in the context of the present application.

Liquids and gases, as used herein, can be rich or poor in one or more components, with "rich" meaning at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% and "poor" can stand for a content of at most 25%, 10%, 5%, 1%, 0.1% or 0.01% on a mole, weight or volume basis. The term "predominantly" may correspond to the definition of "rich". Liquids and gases can also be enriched or depleted in one or more components, these terms referring to a content in a starting liquid or a starting gas from which the liquid or gas was obtained. The liquid or the gas is "enriched" if this or this at least 1.1 times, 1.5 times, 2 times, 5 times, 10 times, 100 times or 1,000 times the content, and "depleted" if this or this is at most 0.9 times, 0.5 times, 0.1 times, 0.01 times times or 0.001 times the content of a corresponding component, based on the starting liquid or the starting gas. If, for example, "oxygen", "nitrogen" or "argon" is mentioned here, this also includes a liquid or a gas that is rich in oxygen or nitrogen, but does not necessarily have to consist exclusively of them. With systems according to embodiments of the present invention, purities in the range of 0.05 ppb oxygen in nitrogen, 0.2 ppb oxygen in argon and 0.2 ppb argon in oxygen can be achieved, for example.

The present application uses the terms "pressure range" and "temperature range" to characterize pressures and temperatures, which is intended to express the fact that corresponding pressures and temperatures in a corresponding system do not have to be used in the form of exact pressure or temperature values in order to to realize the inventive concept. However, such pressures and temperatures typically range within certain ranges, for example ±1%, 5% or 10% around an average value. Corresponding pressure ranges and temperature ranges can be in disjunctive ranges or in ranges that overlap one another. In particular, for example, pressure ranges include unavoidable or expected pressure losses. The same applies to temperature ranges. The values specified in bar for the pressure ranges are absolute pressures.

A "condenser evaporator" refers to a heat exchanger in which a first, condensing fluid stream enters into indirect heat exchange with a second, evaporating fluid stream. Each condenser evaporator has a condensing space and an evaporating space. Condensation and evaporation chambers have liquefaction and evaporation passages. The condensation (liquefaction) of the first fluid stream is carried out in the liquefaction chamber, and the evaporation of the second fluid stream is carried out in the evaporation chamber. The evaporating and condensing spaces are formed by groups of passages which are in heat exchange relationship with each other. The so-called main condenser is a condenser evaporator via which a high-pressure column and a low-pressure column of a plant for the low-temperature separation of air are coupled to one another in a heat-exchanging manner. The term “supercooling countercurrent flow” is intended here to denote a heat exchanger in which one or more streams of material which are transferred between the rectification columns of a rectification column system of the type used here are supercooled. In countercurrent to this, in particular one or more material streams which are carried out from the rectification column system and the entire plant can be heated. The supercooling counterflow is present in addition to the so-called main heat exchanger, which is characterized in that at least the majority of the air fed to the rectification column system is cooled in it. In principle, the air separation plant of the invention can also be designed without a supercooling counterflow.

The term "cold box" is understood here to mean a temperature-insulating housing in which process engineering apparatus operated at low, in particular cryogenic, temperatures are installed. A plant for the low-temperature separation of air can comprise one or more corresponding cold boxes and, in particular, can be created in a modular manner from corresponding cold boxes, as is also the case within the scope of the present invention. In a cold box, several parts of the plant, such as separating devices such as columns and the associated heat exchangers, can be attached together with the piping to a supporting steel frame, which is clad on the outside with metal plates. The interior of the enclosure thus formed is filled with insulating material such as perlite to prevent heat ingress from the environment. Partial or complete prefabrication of cold boxes with the corresponding devices in the factory is also possible, so that they have to be finished or only connected to one another on the construction site if required. Temperature-insulated line modules and, if necessary, housed in cold boxes can be used for the connection. In typical cold boxes, the system components are usually installed with a minimum distance from the wall to ensure adequate insulation. The piping in a cold box is preferably designed without flange connections, ie completely welded or via suitable transition components, in order to prevent leaks from occurring. Due to the temperature differences that occur, there may be expansion bends in the piping. Components requiring maintenance are typically not arranged in the cold box, so that the interior of the cold box is advantageously is maintenance free. Valves can, for example, be designed as so-called angle valves in order to enable repairs to be carried out from outside. The valve sits in the cold box wall; the tubing is routed to the valve and back again.

Pipelines and apparatus are made of aluminum or stainless steel, the latter especially, but not exclusively, at very high operating pressures. The transition component according to the invention makes it possible to connect these materials. The cold box is very often painted in white, but also in other light colors. A penetration of moisture from the ambient air, which would freeze on the cold system parts, can be prevented, for example, by continuously flushing the cold box with nitrogen, for example.

As used herein, the relative spatial terms "above," "below," "above," "below," "above," "below," "beside," "side-by-side," "vertical," "horizontal," etc. refer to the spatial alignment of the rectification columns of an air separation plant or other components in normal operation. An arrangement of two components "on top of each other" is understood here to mean that the upper end of the lower of the two components is at a lower or the same geodetic height as the lower end of the upper of the two components and the projections of the two parts of the apparatus intersect in a horizontal plane . In particular, the two components are arranged exactly one above the other, ie the axes of the two components run on the same vertical straight line. However, the axes of the two components do not have to be exactly perpendicular to each other, but can also be offset from one another, especially if one of the two components, for example a rectification column or a column part with a smaller diameter, is to have the same distance to the metal jacket of a cold box as another with a larger one Diameter. In the case of a multi-part rectification column, terms such as "functionally below" or "functionally above" refer to the arrangement of sub-columns that they would have if the rectification column were of one-piece design.

Advantages of the Invention

The present invention relates to a plant for the low-temperature separation of air, which has a rectification column system with a high-pressure column, a low-pressure column and an argon column, the low-pressure column and optionally also the argon column (in each case) is divided at least into a base part and a top part, as already described, for example, in the cited EP 2 965 029 B1. Furthermore, the system optionally has a pure oxygen column.

If available, the pure oxygen column is used to obtain high-purity or ultra-high-purity oxygen with a residual content of foreign components of up to typically 0.05 ppb or 1 ppb of methane, argon, krypton, xenon, nitrogen, hydrogen, carbon monoxide, carbon dioxide etc., possibly but also above or below. If present, the pure oxygen column is fed with liquid from an intermediate point of the argon column, which liquid is fed in at the top of the pure oxygen column. In the case of the optionally present two-part argon column, this intermediate point is in particular in the base part and in any case in particular above a lowermost separating section which serves to separate components with a higher boiling point than oxygen, in particular hydrocarbons, carbon dioxide, krypton and xenon.

The argon column can in particular be a crude argon column which is used in addition to a pure argon column. Instead of a crude argon column and a pure argon column, it is also possible to provide a single column for obtaining an argon product, which partially combines the functions of crude and pure argon columns by having a further section provided for separating nitrogen. If an argon column is mentioned below, this can in particular be a crude argon column that is present in addition to a pure argon column, but also a correspondingly modified crude argon column that does not have a pure argon column in addition to it.

Merely for clarification, the transfer of fluids between the columns and partial columns that are used according to the invention is summarized below. Thus, bottom liquid from the pressure column, optionally after being used as cooling medium in a top condenser of the argon column and possibly a pure argon column, if present, is fed into the top section of the low-pressure column. Top gas from the pressure column is condensed in parts in a main condenser connecting the pressure column and the foot section of the low-pressure column in a heat-exchanging manner and returned to the pressure column and discharged as a product from the air separation plant. Sump liquid of the foot part of the At least part of the low-pressure column is discharged as product from the air separation unit. Top gas from the bottom part of the low-pressure column is fed into the top section of the low-pressure column, in particular below the lowest rectification section. Additional overhead gas from the bottom part of the low-pressure column is fed into the argon column, in particular below the lowest rectification section, or into the bottom part thereof, if this is designed to be subdivided accordingly. Top gas of the bottom part of the argon column is fed into the top section of the argon column, in particular below the lowermost rectification section, if the argon column is designed to be subdivided accordingly. Bottom liquid from the top section of the argon column is fed into the bottom section of the argon column, if the argon column is designed to be divided accordingly, in particular above the uppermost rectification section, for which purpose a pump is used in particular.

The terms "bottom part" and "top part" refer to the sections of the correspondingly divided and thus two-part columns which, in their function, in particular with regard to the fractions or streams occurring there, correspond to the lower or upper sections of conventional, one-part columns are equivalent to. A foot part has, for example, a sump tank, and a head part has, for example, a top condenser. The head part is therefore that part of the column which is connected to a corresponding condenser and in which reflux is fed to the corresponding column. In a one-piece low-pressure column of known air separation plants, an oxygen-rich liquid fraction is obtained in the bottom, which can be drawn off as oxygen product. This also takes place in a sump or lower region of a foot part of a two-part low-pressure column. A gaseous nitrogen product can be drawn off at the top of a one-piece low-pressure column of known air separation plants, provided that it is equipped accordingly, or so-called impure nitrogen. The same applies to the upper region of a top part of a low-pressure column designed in two parts. At the top of a one-piece argon column (for the term "argon column" see the explanations above), and correspondingly at the top of a top part of a two-piece argon column, a crude argon stream or an argon product stream is withdrawn from the bottom of a one-piece argon column, and correspondingly from a lower one Area of a foot part of a two-piece trained argon column, the resulting bottom product is fed back into the low-pressure column.

In the context of the present invention, the low-pressure column is divided into the top and bottom sections, in particular above the so-called oxygen section. As pointed out by Häring (supra) with reference to Figure 2.4A, argon, although present in atmospheric air at a level of less than 1 mole percent, exerts a strong influence on the concentration profile in the low pressure column. Thus, the separation in the lowermost rectification section of the low pressure column, which typically comprises 30 to 80 theoretical or practical plates, can be regarded as an essentially binary separation between oxygen and argon. This rectification section is the oxygen section mentioned. Only from the exit point for the gas transferred to the crude argon column or in the case of the subdivision carried out according to the invention above the oxygen section does the separation change into a ternary separation of nitrogen, oxygen and argon within a few theoretical or practical trays.

The term "rectification section" is intended here to mean any section within a rectification column or column section of a multipart rectification column which is set up to carry out a rectification and is designed for this purpose in particular with appropriate mass transfer structures such as separating trays or ordered or disordered packing. In particular, fluid withdrawals or feed points, for example side withdrawals, can be provided between rectification sections. The "bottom" of the rectification column is located below a (functionally) lowest rectification area, and its "top" is above the (functionally) upper rectification area.

Overall, the present invention proposes a plant for the low-temperature separation of air, which has a rectification column system with a high-pressure column, a low-pressure column and an argon column and a cold box system with a first cold box, a second and a third cold box. Further cold boxes are possible, for example a total of four cold boxes, with the low-pressure column being divided at least into a foot part and a head part and, if necessary, a main heat exchanger box being additionally provided. In the context of the present invention, the bottom part and the top part of the low-pressure column are arranged next to one another in such a way that an orthogonal projection of the bottom part of the low-pressure column onto a horizontal plane does not intersect with an orthogonal projection of the top part of the low-pressure column onto the horizontal plane. In particular, there is a cross-sectional plane that intersects the bottom and top of the low pressure column.

Optionally, within the scope of the present invention, the argon column can also be divided into at least a base part and a top part, with the base part and the top part of the argon column being arranged next to one another in such a way that an orthogonal projection of the base part of the argon column on the horizontal plane mentioned coincides with an orthogonal projection of the top part of the argon column does not overlap with the horizontal plane. In particular, there is a cross-sectional plane that intersects the bottom and top of the argon column.

In contrast, the high-pressure column is arranged in the context of the present invention below the base of the low-pressure column in such a way that an orthogonal projection of the high-pressure column on the horizontal plane intersects with the orthogonal projection of the base of the low-pressure column on the horizontal plane, with the longitudinal axes of the high-pressure column and the base of the low-pressure column in particular lie along a common main axis or there is a vertical axis which intersects the high-pressure column and the foot part of the low-pressure column.

In the context of the present invention, the high-pressure column is arranged together with the base part of the low-pressure column in the first cold box, and the top part of the low-pressure column is arranged in the second cold box. According to the invention, the argon column or one or more sections of the argon column is or are in the first cold box and/or the second cold box. Alternatively, the argon column or all parts of the argon column are accommodated in a third cold box. As an alternative, there is a separate box for the bottom section and for the top section of the argon column.

The arrangement proposed according to the invention results in particular in a simple construction with small transport dimensions and enables a possible low box height (not higher than the church tower or near the airport...),. A "cold part of the plant" is understood here as meaning an apparatus or part of an apparatus which is operated at low temperatures, in particular below -50° C., during regular operation of the plant.

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

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

In the invention, the pure oxygen column is arranged in one of the cold boxes, specifically in the same cold box as the argon column or a first section of the argon column.

The pure oxygen column and the argon column or a first section (for example the foot section) of the argon column are arranged next to one another in the system used according to the invention in such a way that an orthogonal projection of the pure oxygen column or an upper part of the pure oxygen column on the horizontal plane coincides with the orthogonal projection of the argon column or the first Section of the argon column does not overlap the horizontal plane. The upper part can be a part of the pure oxygen column which is not occupied by a bottom evaporator arranged in the bottom of the pure oxygen column. Due to its dimensioning, the latter can also occupy a space which is significantly larger in cross section than the upper part of the pure oxygen column and can optionally be arranged eccentrically (relative to a central axis of the upper part). In this case, the lower part of the Pure oxygen column with the bottom evaporator also partially intersect in the orthogonal projection on the horizontal plane with the orthogonal projection of the foot part of the argon column on the horizontal plane.

In addition, the top section of the low-pressure column and the pure oxygen column or an upper part of the pure oxygen column are preferably arranged next to one another in such a way that an orthogonal projection of at least the pure oxygen column or an upper part of the pure oxygen column onto the horizontal plane coincides with the orthogonal projection of the top section of the low-pressure column or the first section of the argon column does not intersect the horizontal plane.

As already expressed in other words above, the pure oxygen column, if present in a corresponding configuration, is fed at a feed point with a first transfer liquid which is removed from the argon column or its base part at a withdrawal point. The columns or column parts mentioned are therefore equipped with appropriate removal and feed points. The removal point from the argon column or its base is, as mentioned, in particular above a rectification section which is used to discharge hydrocarbons. The removal point for the first transfer liquid is in particular 1 to 30 theoretical plates above a bottom of the argon column or from its foot section.

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

Advantageously, the pure oxygen column and the argon column or its base are arranged such that the removal point for the transfer liquid from the argon column or its base is located geodetically above the feed point for the transfer liquid into the pure oxygen column. In this way, the transfer liquid can run into the pure oxygen column in particular without using a pump, which on the one hand reduces the cost of a corresponding Pump saved and on the other hand avoids possible contamination by a corresponding pump. The point at which the transfer fluid is fed into the pure oxygen column is in particular above an uppermost rectification section of the pure oxygen column.

In one embodiment of the invention with a correspondingly subdivided argon column, it is provided in particular that the foot part of the argon column is fed with a second transfer liquid at a feed point located in particular below a lowermost rectification section in the foot part of the argon column, which is fed to the top part of the low-pressure column at a point in particular below one lowermost rectification section in the head part of the low-pressure column is removed. The columns or column parts mentioned are therefore equipped with appropriate removal and feed points.

In this configuration, the top part of the low-pressure column and the bottom part of the argon column can be arranged in such a way that the removal point for the second transfer liquid from the top part of the low-pressure column is geodetically above the feed point for the further transfer liquid in the bottom part of the argon column. In this way, the bottom part of the argon column can combine its bottom liquid and the bottom liquid of the top section of the low-pressure column and be fed back to the bottom section of the low-pressure column by means of only one (i.e. by means of a common) pump, which is ideally designed redundantly.

An empty section is preferably arranged in the foot part of the argon column or its foot part. A void section is located inside the shell of a column and extends across a vertical portion of the column. There are no mass transfer elements in an empty section, so it plays no role in the mass transfer. At first it seems absurd to provide such a section since the column shell becomes more expensive. In the context of the exchange of one or more transfer liquids, however, it is operatively advantageous in the invention to set the material exchange region of the head part of the low-pressure column relatively high (above the empty section) and the bottom relatively low (below the empty section). In particular, the empty section is arranged in the lower region of the column, in particular immediately above the lower end of the column jacket. If a corresponding system has a supercooling counterflow, it can be arranged in one of the cold boxes. In the configuration just explained, the supercooling countercurrent can be arranged in particular below the top part of the low-pressure column.

In this embodiment of the invention, provision can therefore be made in particular for the top part of the low-pressure column to be arranged geodetically above a supercooling countercurrent flow. If bottom liquid from the top section of the low-pressure column is to be able to drain into the bottom section of the argon column from above a corresponding rectification section into the pure oxygen column, it must be positioned sufficiently high. In this case, the bottom of the bottom section of the argon column can be extended by what is known as an "empty section", i.e. an empty area or empty section downwards, so that it can be ensured at the same time that, in a corresponding configuration, liquid can flow from the top part of the low-pressure column into the bottom of the Foot part of the argon column can run off. As a result, 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 configuration just mentioned, it can also be provided that the top part of the low-pressure column is fed with a second transfer liquid at a feed point located in particular below a bottom rectification section in the top part of the low-pressure column, which is fed to the bottom part of the argon column at a point in particular below a bottom rectification section in the extraction point lying at the foot of the argon column. The columns or column parts mentioned are therefore equipped with appropriate removal and feed points. The base of the argon column and the top of the low-pressure column are arranged in this embodiment such that the removal point for the further transfer liquid from the base of the argon column is geodetically above the feed point for the further transfer liquid in the top of the low-pressure column. In this way, the bottom liquid and bottom liquid of the bottom section of the argon column can be combined in the head part of the low-pressure column and returned to the bottom section of the low-pressure column by means of only one pump. In a corresponding system which has a supercooling counterflow, this can be arranged in the configuration just explained, in particular below the foot part of the argon column.

In particular, it can be provided that the top part of the low-pressure column and the top part of the argon column are arranged next to one another in such a way that the orthogonal projection of the top part of the low-pressure column onto the horizontal plane does not intersect with the orthogonal projection of the top part of the argon column onto the horizontal plane. Accordingly, there is a cross-sectional plane that intersects the top of the low pressure column and the top of the argon column.

In the context of the present invention, cold box heights of 35 to 50 meters, in particular approx. 43 meters, can be maintained. The high-pressure column can in particular have a height of 15 to 30 meters, in particular 25.8 meters, and the base part of the low-pressure column can in particular have a height of 7 to 20 meters, for example 14.8 meters. The height of the foot part of the low-pressure column is defined in particular by the height of the main condenser housed in it and the separating devices, the so-called

Oxygen section, both of which can be in particular 5 to 14 meters, for example 7.4 meters. The diameter can in particular be 1.5 to 4 meters, for example approximately 2.8 meters. The base part of the argon column has a height of 25 to 45 meters, in particular approx. 39 meters, for example.

The top part of the low-pressure column has in particular a height of 18 to 30 meters, for example 23 meters (with a diameter of 2.4 to 3 meters, for example about 2.6 meters) or a height of 25 to 30 meters, for example Approx. 27 meters (with a diameter of 1.2 to 4.0 meters, for example approx. 2.45 meters). The dimensions depend in particular on the packing density used. The top part of the argon column can have appropriate dimensions.

Against this background, the arrangements and configurations proposed according to the invention enable a compact design in particular. As in known plants, the foot part of the low-pressure column is connected to the high-pressure column via a condenser evaporator for mutual heat exchange, and the foot part of the low-pressure column and the high-pressure column are arranged in particular in a common column jacket or in several column jackets connected on the jacket side, in particular in the form of one well-known Linde double column (but without the head part of the low-pressure column).

The supercooling countercurrent can in particular have a vertical space requirement of up to 45 meters, for example approx. 8 meters, if it is mounted upright Foot of the argon column. The previously explained arrangement variants for the supercooling counterflow are particularly advantageous because they are associated with a space-saving arrangement. Other arrangement variants of the supercooling counterflow, for example in a heat exchanger box, etc., can also be advantageous.

(A) The pure oxygen column can be arranged in the first cold box next to the high-pressure column, the base part of the low-pressure column and the base part of the argon column (with a corresponding subdivision) in such a way that an orthogonal projection of at least an upper part (for reasons and further explanations see above) of the pure oxygen column on the horizontal plane does not intersect with the orthogonal projection of the high pressure column on the horizontal plane and the orthogonal projection of the bottom part of the low pressure column on the horizontal plane and the orthogonal projection of the bottom part of the argon column.

The connecting pipelines are minimized.

If this arrangement (A) is no longer transportable due to the dimensions, the HDS can be moved to a separate box with the lower part of the NDS. Then ideally the upper part of the low-pressure column with the argon column is in a second cold box. The reboiler of the pure oxygen column can be located in the shadow of the low-pressure column and can be arranged asymmetrically. The argon column or its sections are arranged in a third cold box. The arrangement of the heights is important. In the context of the present invention, the foot part of the argon column can (with a corresponding subdivision of the same) be set up in particular for separating off high-boiling components, but also other impurities, in particular also separated off to avoid enrichment.

In the context of the present invention, in particular a lower region of the top part of the low-pressure column and a lower region of the bottom part of the argon column (with a corresponding subdivision) can be fluidically coupled via a pump to an upper region of the bottom part of the low-pressure column.

Merely for clarification, it should be mentioned here again that the system proposed according to the invention advantageously has means that are set up to feed the high-pressure column with cooled compressed air, means that are set up to feed the low-pressure column with fluid from the high-pressure column, and means arranged to feed the argon column with fluid from the low pressure column.

Finally, the present invention also extends to a method for the low-temperature separation of air, for the features of which reference is expressly made to the corresponding independent patent claim. In particular, a system is used in such a method, as has been explained above in different configurations. With regard to the features and advantages of the proposed method and possible configurations, reference is therefore expressly made to the explanations relating to the system according to the invention.

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

character description

FIG. 1 illustrates a plant for the cryogenic separation of air, which can form the basis of an embodiment of the invention, in the form of a simplified process flow diagram. FIG. 2 illustrates an arrangement of components of a system designed according to an embodiment of the invention for the low-temperature separation of air in a side view and in a simplified representation.

FIG. 3 illustrates an arrangement of components of a system designed according to an embodiment of the invention for the low-temperature separation of air in a top view and in a simplified representation.

FIG. 4 shows a modification of FIG. 2 in which a blank section is used.

If plant components of a plant for the low-temperature separation of air (hereinafter also referred to as “air separation plant” for short) are described below, the corresponding explanations also apply to a process carried out with them and vice versa.

Embodiments of the invention

FIG. 1 shows an air separation plant which is set up for obtaining an argon product and a pure oxygen product and is denoted overall by 100 .

The air separation plant 100 has a rectification column system 10, which includes a high-pressure column 11, a low-pressure column divided into a base part 12 and a top part 13, a (crude) argon column also divided into a base part 14 and a top part 15, and a pure argon column 20. A pure oxygen column is denoted by 18 . A block labeled 1 includes the usual components present in an air separation plant of the type illustrated for compressing, cleaning and cooling the feed air, in particular also a main heat exchanger of a known type.

The foot part 12 and the top part 13 of the low-pressure column and the foot part 14 and the top part 15 of the argon column are structurally separate from one another and are arranged next to one another in the sense explained above. The foot part 12 and the head part 13 of Together, low-pressure columns correspond functionally to a conventional low-pressure column of a double column. The high-pressure column 11 and the bottom and top part 12, 13 of the low-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 bottom part 14 and the top part 15 of the argon column and the pure argon column 20 is connected .

In the illustrated embodiment, cooled and compressed feed air is fed in the form of two streams a, b into the high-pressure column 11 and the top part 13 of the low-pressure column. The air separation plant 100 can be designed for internal compression and can be designed as desired within the framework shown here. Further compressed feed air is passed in the form of a stream c through a non-separately designated bottom evaporator of the pure oxygen column 18, where it is at least partially condensed and then also, now designated d, fed into the top section 13 of the low-pressure column. The specific type of air feed into the column arrangement is not essential to the invention and can be designed in any way (with/without throttle flow, with/without air feed into the low-pressure column or its top section 13, etc.). This also applies to the provision of turbines for refrigeration, which may or may not be provided.

The high-pressure column 11 and the foot part 12 of the low-pressure column are in a heat-exchanging connection via a condenser evaporator 19, the so-called main condenser, and are designed as a structural unit. In principle, however, the invention can also be used in systems in which the high-pressure column 11 and the low-pressure column (or their foot part 12) are arranged separately from one another and have a separate condenser evaporator 19, i.e. not integrated into the columns.

The operation of the air separation plant 100 results directly from the illustration according to FIG. 1. Reference is therefore made to the specialist literature cited at the outset.

In particular, the bottom part 12 and the top part 13 of the low-pressure column are fluidly coupled to one another here in that top gas from an upper region of the bottom part 12 of the low-pressure column in the form of a stream e a lower region of the top part 13 of the low-pressure column is transferred. As also explained with reference to Figure 2, the arrangement of the top part 13 of the low-pressure column and the bottom part 14 of the argon column in the example shown is such that bottom liquid in the form of a stream f from a lower region of the top part 13 of the low-pressure column into a lower region of the bottom part 14 of the argon column can run off, into which a further part of the top gas from the upper region of the foot part 12 of the low-pressure column is fed in the form of a stream g. In this way, bottom liquid from the top part 13 of the low-pressure column and the bottom part 14 of the argon column is collected in the bottom of the bottom part 14 of the argon column and can be pumped back into an upper region of the bottom part 12 of the low-pressure column in the form of a stream h by means of a common pump 110. A reverse arrangement is also possible, as mentioned.

Top gas of the bottom section 14 of the argon column is transferred to a lower region of the top section 15 of the argon column and liquid is pumped back with a pump 120 accordingly. The integration of the pure argon column 20 can essentially correspond to what is customary in the art. The argon column consisting of the base part 14 and the top part 15 is fluidly connected parallel to the low-pressure column or its base part 12 and top part 13, so that the corresponding top gas from an upper area of the base part 12 of the low-pressure column also flows into a lower area of the base part 14 of the argon column transferred and bottoms liquid is returned from the lower region of the foot part 14 of the argon column to the upper region of the foot part 12 of the low-pressure column. In particular, the same pump is used here that is also used to return the bottom liquid from the lower region of the top part 13 of the low-pressure column to an upper region of the bottom part 12 of the low-pressure column.

Furthermore, the bottom part 14 and the top part 15 of the argon column are fluidly coupled to one another in that top gas is transferred from an upper area of the bottom part 14 of the argon column to a lower area of the top part 15 of the argon column and by means of a (further) pump sump liquid is transferred from a lower area of the top part 15 of the argon column is returned to an upper region of the bottom part 14 of the argon column. The pure oxygen column 18 is fed here at a feed point 18a with a transfer liquid in the form of a stream t, which is removed from the base part 14 of the argon column at a removal point 14a. The pure oxygen column 18 and the foot part 14 of the argon column are arranged in such a way that the removal point 14a for the transfer liquid from the foot part

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 it can be transferred into the pure oxygen column 18 without a pump.

The bottom part 14 of the argon column is also fed at a feed point 14b with another transfer liquid in the form of the already mentioned stream f, which is removed from the top part 13 of the low-pressure column at a withdrawal point 13b, with the top part 13 of the low-pressure column and the bottom part 14 of the argon column in the illustrated example are arranged such that the removal point 13b for the further transfer liquid from the head part 13 of the low-pressure column is above the feed point 14b for the further transfer liquid in the foot part 14 of the argon column.

An integration of the components of the air separation plant 100 in cold boxes is illustrated in FIG. 2 in the form of a simplified side view, the components of the air separation plant 100 being indicated with identical reference symbols as explained above for FIG. As in Figure 1, these are shown in side view, but are even more simplified. The fluid connections are not shown, but result in accordance with the illustration in accordance with FIG.

The foot part 12 and the top part 13 of the low-pressure column are arranged side by side here in such a way that an orthogonal projection of the foot part 12 of the low-pressure column onto a horizontal plane H does not intersect with an orthogonal projection of the top part 13 of the low-pressure column onto the horizontal plane H, and the foot part 14 and the head part 15 of the argon column are also arranged side by side in such a way that an orthogonal projection of the foot part 14 of the argon column on the horizontal plane H coincides with an orthogonal projection of the head part

15 of the argon column on the horizontal plane H does not overlap. In contrast, the high-pressure column 11 is arranged below the base part 12 of the low-pressure column in such a way that an orthogonal projection of the high-pressure column 11 on the horizontal plane H intersects with the orthogonal projection of the base part 12 of the low-pressure column on the horizontal plane H.

The pure oxygen column 18 and the foot part 14 of the argon column are arranged side by side in such a way that an orthogonal projection of at least an upper part (further explanations above) of the pure oxygen column 18 onto the horizontal plane H does not intersect with the orthogonal projection of the foot part 14 of the argon column onto the horizontal plane H,

Furthermore, in the air separation plant 100, the top part 13 of the low-pressure column and the top part 15 of the argon column are arranged next to one another in such a way that the orthogonal projection of the top part 13 of the low-pressure column on the horizontal plane H intersects with the orthogonal projection of the top part 15 of the argon column on the horizontal plane H.

The high-pressure column 11, the bottom part 12 of the low-pressure column and the bottom part 14 of the argon column and the pure oxygen column 18 are in the first cold box 110 and the top part 13 of the low-pressure column and the top part 15 of the argon column are in the second cold box 120, as are the pure argon column 20. This results in the advantages of a corresponding embodiment according to the invention.

As illustrated here by dashed lines, subcooling counterflow 17 can be arranged in particular below head part 13 of the low-pressure column in second cold box 120 in such a way that an orthogonal projection of subcooling counterflow 17 onto horizontal plane H intersects with the orthogonal projection of head part 13 of the low-pressure column onto precisely this horizontal plane H.

As explained, the top part 13 of the low-pressure column can be designed with a lower packing density than the top part 15 of the argon column, and the The foot part 14 of the argon column can be set up to separate off methane. As explained above and shown in detail in Figure 1, a lower area of the top part 13 of the low-pressure column and a lower area of the bottom part 14 of the argon column can also be fluidically coupled to an upper area of the bottom part 12 of the low-pressure column via a (common) pump.

FIG. 3 illustrates the components shown in FIG. 2 in a plan view, the horizontal plane H lying parallel to the plane of the paper and express reference is made to the explanations relating to FIG. 2 for further details.

FIG. 4 corresponds to FIG. 2 except for the empty section 14a of the foot part 14 of the argon column. The column shell extends uninterruptedly over the entire length of the column (ie also the empty section 14a shown in dashed lines).

Only above the empty area 14a are mass transfer elements such as ordered packing installed. The liquid drips from the lower end of the mass transfer elements through the void section into the column bottom at the lower end of the void section 14a.

Claims

25 Claims Plant (100) for the low-temperature decomposition of air, the - A rectification column system (10) with a high-pressure column (11), a low-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 a foot section (14) of the argon column (14, 15) are arranged side by side in such a way that an orthogonal projection of at least an upper part of the pure oxygen column (18) onto the horizontal plane (H) coincides with the orthogonal projection of the argon column (14, 15) or the foot section (14 ) of the argon column (14, 15) does not overlap the horizontal plane (H), - The pure oxygen column (18) has a feed point (18a) for a first transfer liquid and the argon column (14, 15) or the foot part (14) of the argon column (14, 15) has a withdrawal point (14a) for the first transfer liquid, the pure oxygen column (18) and the foot part of the argon column (14, 15) are arranged in such a way that the removal point (14a) for the first transfer liquid is located geodetically above the feed point (18a) for the first transfer liquid, characterized in that - the low-pressure column (12, 13) is divided at least into a foot part (12) and a head part (13), - the bottom part (12) and the top part (13) of the low-pressure column (12, 13) are arranged next to one another in such a way that an orthogonal projection of the bottom part (12) of the low-pressure column (12, 13) on a horizontal plane (H) coincides with an orthogonal projection of the Head part (13) of the low-pressure column (12, 13) does not overlap the horizontal plane (H), - The high-pressure column (11) is arranged below the foot part (12) of the low-pressure column (12, 13) that a Orthogonal projection of the high-pressure column (11) on the horizontal plane (H) with the orthogonal projection of the foot part (12) of the low-pressure column (12, 13) on the horizontal plane (H) intersects the pure oxygen column (18) and the argon column (14, 15) or the foot part (14) of the argon column (14, 15) in such a way are arranged next to one another in such a way that an orthogonal projection of at least an upper part of the pure oxygen column (18) onto the horizontal plane (H) coincides with the orthogonal projection of the argon column (14, 15) or the foot part (14) of the argon column (14, 15) onto the horizontal plane ( H) does not overlap, the cold box system has a first cold box (110), a second cold box (120) and a third cold box (130), - the high-pressure column (11) is arranged together with the foot part (12) of the low-pressure column (12, 13) in the first cold box (110), the head part (13) of the low-pressure column (12, 13) is arranged in the second cold box (120). is, - the argon column (14, 15) or one or more sections of the argon column (14, 15) is or are arranged in the third cold box (130), and the pure oxygen column (18) is arranged in the second cold box. Plant (100) according to Claim 1, in which the argon column (14, 15) is divided at least into a foot part (14) and a head part (15), the foot part (14) and the head part (15) of the argon column (14, 15) are arranged side by side in such a way that an orthogonal projection of the foot part (14) of the argon column (14, 15) on the horizontal plane (H) coincides with an orthogonal projection of the head part (15) of the argon column (14, 15) on the horizontal plane (H) does not overlap. Plant (100) according to Claim 1 or 2, in which the argon column (14, 15) is designed as a crude argon column and a pure argon column (20) is also provided, the pure argon column (20) in the first cold box (110) or the second cold box (120) is arranged, in particular in the cold box, in which the top part (15) of the argon column (14, 15) designed as a crude argon column is arranged. Plant (100) according to one of the preceding claims, in which the withdrawal point (14a) for the first transfer liquid is 1 to 30 theoretical plates above a bottom of the bottom part of the argon column (14, 15). Plant (100) according to one of the preceding claims, in which the foot part (14) of the argon column (14, 15) has a feed point (14b) for a second transfer liquid and the top part (13) of the low-pressure column (12, 13) has a withdrawal point ( 13b) for the second transfer liquid, the top part (13) of the low-pressure column (12, 13) and the foot part (14) of the argon column (14, 15) being arranged in such a way that the withdrawal point (13b) for the second transfer liquid is above the Feed point (14b) is for the second transfer liquid. Plant (100) according to one of the preceding paragraphs, in which an empty section (13a) of the argon column (14, 15) or in the bottom part (14) of the argon column is arranged. Plant (100) according to Claims 1 to 6, which has a supercooling countercurrent (17) which is located in the first or second cold box (110, 120), in particular in the second cold box (120) below the top part (13) of the low-pressure column (12, 13) is arranged. Plant (100) according to one of the preceding claims, in which the head part (13) of the low-pressure column (12, 13) has a feed point (13c) for a second transfer liquid and the foot part (14) of the argon column (14, 15) has a withdrawal point ( 14c) for the second transfer liquid, the foot part (14) of the argon column (14, 15) and the top part (13) of the low-pressure column (12, 13) being arranged in such a way that the withdrawal point (14c) for the second transfer liquid is above the feed point (13c) for the second transfer liquid. Plant (100) according to claim 8, comprising a subcooling counterflow (17) arranged below the bottom part (14) of the argon column (14, 15). Plant according to one of the preceding claims, in which all cold apparatus parts are arranged in the first or the second cold box (110, 120) and no third cold box is used. 28 Plant according to one of the preceding claims, in which the first section (14) of the crude argon column (14, 15) is formed by its foot part. Process for the low-temperature separation of air, in which a plant (100) according to one of Claims 1 to 11 is used.