KR20240059622A - Plant and method for low temperature separation of air - Google Patents

Abstract

The present invention provides a rectification column system (10) comprising a high pressure column (11), divided low pressure columns (12, 13) and argon columns (14, 15), and a first cold box (coldbox) (110), a second It relates to a plant (100) for low-temperature separation of air, having a cold box system (20) comprising a cold box (120) and a third cold box (130). The high pressure column (11) is arranged below the lower section (12) of the low pressure columns (12, 13). The high-pressure column 11 is placed in a first cold box 110 together with the lower parts 12 of the low-pressure columns 12, 13, and the upper parts 13 of the low-pressure columns 12, 13 are placed in the second cold box 110. It is placed in box 120. It is proposed that the argon column 14 , 15 or one or more sections of the argon column 14 , 15 are disposed in the third cold box 110 , 120 . A pure oxygen column 18 is placed in the second cold box. The invention likewise provides a corresponding method.

Description

Plant and method for low temperature separation of air

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

The production of air products in liquid or gaseous state by cryogenic separation of air in air separation plants is known, see for example H.-W. (editor), Industrial Gases Processing, Wiley-VCH, 2006, in particular Section 2.2.5, "Cryogenic Rectification"].

The air separation plant has a two-column system, especially a double-column system, as well as a rectifying column system, which can be designed as a triple-column or multi-column system. In addition to rectification columns for obtaining nitrogen and/or oxygen in liquid and/or gaseous state, ie for nitrogen-oxygen separation, rectification columns may be provided for obtaining further air components, in particular argon.

The rectification columns of the mentioned rectification column systems operate at different pressure levels. Known dual-column systems have what is known as a high pressure column (also called a pressure column, medium pressure column, or lower column) and what is known as a low pressure column (also called an upper column). High pressure columns are typically operated at pressures of 4 to 14 bar, especially approximately 5.3 bar, or approximately 11 bar. Low pressure columns are typically operated in the pressure range of 1 to 4 bar, especially around 1.4 bar as well as 3 bar. In certain cases, higher pressures can also be used in low pressure columns, which can also be operated at 2 to 4 bar, and pressure columns between 9 and 14 bar. The specific pressures mentioned here and below are the absolute pressures at the top of each indicated rectification column.

In known methods and plants for low-temperature separation of air, an oxygen-rich, nitrogen-depleted liquid is formed in the lower region of the high pressure column and is discharged from the high pressure column. This liquid, in particular also containing argon, is fed at least partially into the low pressure column, where it is further separated. Before being fed into the low pressure column, it can be at least partially evaporated, and optionally the evaporated and non-evaporated fractions can be fed into the low pressure column at different locations.

To extract argon, an air separation plant with a crude argon column and a pure argon column can be used. One example is Haring ( 2.3A in the literature (see above), beginning with the section “Rectification in the Low-pressure, Crude and Pure Argon Column” on page 26, and also in the “Cryogenic Production of Pure Argon” section on page 29. It is described starting from . As described therein, argon is accumulated in the corresponding plant to a certain height in a low pressure column. At this or another vantage point, optionally also below the argon maximum, an argon-enriched gas with an argon concentration typically of 5 to 15 mole percent may be withdrawn from the low pressure column and passed to the crude argon column. The corresponding gas typically contains about 0.05 to 100 ppm of nitrogen and essentially oxygen in addition. It should be clearly emphasized that the values shown for gas drawn from low pressure columns are only typical example values.

The crude argon column serves to substantially separate oxygen from the gas discharged from the low pressure column. The oxygen separated in the crude argon column or corresponding oxygen-rich fluid can be returned to the low pressure column in liquid form. The oxygen or oxygen-enriched fluid is typically fed into the low pressure column at several theoretical or practical plates below the feed point to the oxygen-enriched, nitrogen-depleted, and optionally at least partially vaporized liquid exiting the high pressure column. do. The gas fraction remaining in the crude argon column during the separation and containing substantially argon and nitrogen is further separated in the pure argon column to obtain pure argon. The crude and pure argon columns have, in particular, an upper condenser that can be cooled by a portion of the oxygen-rich, nitrogen-depleted liquid leaving the high-pressure column, which liquid partially evaporates during this cooling. Other fluids may also be used for cooling.

In principle, it is also possible to omit the pure argon column in corresponding plants, which typically ensures that the nitrogen content in the argon transition is below 1 ppm. However, this is not a mandatory requirement. Argon of the same quality as that from a conventional pure argon column exits the crude argon column or a comparable column, which in this case is typically slightly lower than the fluid delivered to the pure argon column. The plates in the condenser, i.e. the section between the upper condenser of the crude argon column and the corresponding outlet, serve in particular as barrier plates for nitrogen. The present invention can be used with such arrangements without pure argon columns. Since the crude argon column or comparable column in such an arrangement is already used for pure argon production and is not intended for crude argon production, it is also referred to below as an “argon column”. Accordingly, the argon column can be a conventional crude argon column (used with or without a pure argon column) or a corresponding crude argon column modified to produce pure argon.

In order to improve the construction height of the corresponding air separation plant and its prefabricability, European Patent No. 2 965 029 B1 proposes dividing the low pressure column into a base part (base section) and an upper part (top section). It is proposed that the base section of the low-pressure column remains installed with the high-pressure column as in a conventional dual-column arrangement, but the upper section of the low-pressure column is stored in a separate cold box. It is also proposed herein to split the crude argon column into a base part (base section) and an upper part (top section) and to house these sections in separate co-boxes. Liquid from the lower region of the upper section of the low-pressure column and the lower region of the base section of the crude argon column are returned to the base section of the low-pressure column by a common pump.

The object of the invention is to further improve the corresponding arrangement, especially with regard to construction effort and costs.

Against this background, the present invention proposes a plant and method for low-temperature separation of air, characterized by the independent claims. Preferred embodiments form the subject of the dependent claims and the description below.

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.

The devices used in air separation plants are described in the cited technical literature, for example by Haring (supra), section 2.2.5.6, “Apparatus” (Apparatus). Accordingly, unless the definitions below differ, explicit reference is made to the cited technical literature for terms used within the framework of this application.

Liquids and gases, as the term is used herein, may be rich or poor in one or more components, with "rich" being at least 75%, 90%, 95%, 99%, 99.5% by mole, weight, or volume. %, 99.9%, or 99.99%, and “insufficient” may refer to an amount of up to 25%, 10%, 5%, 1%, 0.1%, or 0.01%. The term “mainly” may correspond to the definition of “abundantly”. Liquids and gases may also be enriched or depleted in one or more components, where these terms refer to the content in the starting liquid or starting gas from which the liquid or gas is extracted. A liquid or gas is “enriched” if it contains more than 1.1, 1.5, 2, 5, 10, 100, or 1000 times the amount of the corresponding component based on the starting liquid or starting gas, and 0.9 It is “depleted” if it contains less than 2x, 0.5x, 0.1x, 0.01x, or 0.001x. By way of example, when reference is made herein to “oxygen,” “nitrogen,” or “argon,” it is also understood to mean a liquid or gas enriched in, but not necessarily comprised solely of, oxygen or nitrogen. By plants according to embodiments of the present invention, purities in the range of, for example, 0.05 ppb oxygen in nitrogen, 0.2 ppb oxygen in argon, and 0.2 ppb argon in oxygen can be achieved.

This application uses the terms "pressure range" and "temperature range" to characterize pressure and temperature, which means that the corresponding pressure and temperature in the corresponding plant can be defined as the exact pressure or temperature values to realize the concept of the present invention. This means that there is no need to use the form. However, these pressures and temperatures typically fall within a range, for example ±1%, 5% or 10% around the mean. In this case, the corresponding pressure ranges and temperature ranges may be in separate ranges or in overlapping ranges. In particular, the pressure range includes, for example, unavoidable or expected pressure losses. The same applies to the temperature range. In this specification, the values expressed in bar units regarding the pressure range are absolute pressures.

“Condenser evaporator” refers to a heat exchanger in which a first condensing fluid stream engages in indirect heat exchange 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 passage or an evaporation passage. Condensation (liquefaction) of the first fluid stream is carried out in a liquefaction chamber and evaporation of the second fluid stream is carried out in an evaporation chamber. Evaporation and liquefaction chambers are formed by a group of passages in heat exchange relationship with each other. The so-called main condenser is a condenser evaporator in which the plant's high-pressure column and low-pressure column for low-temperature separation of air are combined in a heat exchange manner.

The term “subcooling heat exchanger” is intended to denote a heat exchanger in which subcooling of one or more material flows passing between the rectifying columns of a rectifying column system of the type used herein is effected. In the countercurrent thereto, one or more material flows can be heated, especially those exiting the entire plant and the rectification column system. In addition to the so-called main heat exchangers, there are subcooling heat exchangers, which are characterized in that at least the majority of the air supplied to the rectification column system is internally cooled. The air separation plant of the invention can in principle be designed without a subcooling heat exchanger.

The term “cold box” is understood here to mean a temperature-insulated enclosure in which process engineering devices operating at low temperatures, in particular cryogenic temperatures, are installed. A plant for low-temperature separation of air may comprise one or more corresponding cold boxes and, in particular, may be produced modularly from corresponding cold boxes, which is also within the scope of the invention. In the cold box, several plant parts, for example separation devices such as columns and associated heat exchangers, may also be fastened together with piping to a supporting steel frame externally covered with sheet-metal plates. The interior of the enclosure formed in this way is filled with an insulating material such as perlite to prevent heat ingress from the environment. It is also possible to partially or completely prefabricate the cold box using corresponding devices in the factory, which then have to be completed at the construction site or connected to each other as required. For the connection, line modules can be used, which are insulated and possibly housed in a cold box. In a typical cold box, plant parts are usually installed at a minimum distance from the walls to ensure sufficient insulation. The piping in the cold box is preferably designed without flange connections, i.e. fully welded, or using suitable transition components according to the invention, in order to avoid the formation of leaks. Because temperature differences occur, expansion bends may exist in the pipe. Components vulnerable to maintenance are typically not arranged in the cold box, so the interior of the cold box is advantageously maintenance-free. The valve can for example be designed as a so-called “corner valve” to allow repair from the outside. In this case, the valve is located on the cold box wall; The pipeline is guided to the valve and back again. Pipelines and devices are manufactured from aluminum or stainless steel, the latter being used particularly, but not limited to, at very high operating pressures. The transition element according to the invention makes it possible to connect such materials. Cold box painting is often white, but other bright colors are also available. By continuously flushing the cold box, for example with nitrogen, the ingress of moisture from the ambient air, which would freeze in the cold plant parts, can be prevented.

Relative spatial terms "top", "bottom", "top", "below", "above", "below", "adjacent", "next to", "vertical", "horizontal", etc. are used herein as normal. Refers to the spatial orientation of the rectification columns or other components of a heavy air separation plant. An arrangement of two components "one above the other" means that the upper end of the lower of the two components has a lower geodetic height than the lower end of the upper of the two components, or the same. Located at a geodesic height, it is understood herein to mean that the projections of the two device parts overlap in the horizontal plane. In particular, the two components are arranged exactly above and below, i.e. the axes of the two components run on the same vertical straight line. However, the axes of the two components do not have to lie exactly perpendicular to each other and may also be offset from each other, especially if one of the two components, for example a rectifying column or column portion with a smaller diameter, has a larger diameter. This is the case if it is at the same distance from the sheet metal jacket of the cold box as the other with . In the case of a rectification column designed in multiple parts, terms such as “functionally below” or “functionally above” refer to the arrangement of the segment columns that the rectification column would have if it were formed in one piece.

Effects of the Invention

The invention relates to a plant for low-temperature separation of air, having a rectification column system with a high-pressure column, a low-pressure column and an argon column, as already described, for example, in the cited European Patent No. 2 965 029 B1. The low pressure column and optionally also the argon column (respectively) are divided into at least a base section and an upper section. Additionally, the plant optionally has a pure oxygen column.

Pure oxygen columns, if present, have high purity residual contents of extraneous components, typically up to 0.05 ppb or 1 ppb of methane, argon, krypton, xenon, nitrogen, hydrogen, carbon monoxide, carbon dioxide, etc., but optionally also more or less. Alternatively, it serves to obtain ultra-high purity oxygen. If present, the pure oxygen column is supplied with liquid from the midpoint of the argon column, which is introduced at the top of the pure oxygen column. In optionally present two-part argon columns, this intermediate point is located particularly within its base section and, in any case, at the lowermost section, which serves to separate components with boiling points higher than oxygen, especially hydrocarbons, carbon dioxide, krypton and xenon. It's above the separation section.

The argon column may be a crude argon column, especially used in addition to a pure argon column. Instead of a crude argon column and a pure argon column, there is a single column for obtaining the argon product, which partially combines with each other the functions of the crude argon column and the pure argon column by having an additional section provided for separating nitrogen. If an argon column is subsequently mentioned, this may in particular be a crude argon column present in addition to a pure argon column, but it may also be a correspondingly modified crude argon column, without a pure argon column next to it.

The fluid transfer between the columns and partial columns used according to the invention is summarized below for illustrative purposes only. Accordingly, the sump fluid of the pressure column is fed into the upper section of the low pressure column, optionally after use as cooling medium in the upper condenser of the argon column and, if present, optionally pure argon column. The top gas of the pressure column is condensed into parts in the main condenser, which connects the base sections of the pressure column and the low pressure column while exchanging heat, is recycled to the pressure column and is discharged as product from the air separation plant. The sump liquid of the base section of the low pressure column is discharged at least partially as product from the air separation plant. The upper gas of the base section of the low-pressure column is fed into the upper section of the low-pressure column, especially down the lowermost rectification section. Additional top gases of the base section of the low-pressure column are fed into the argon column, especially below the lowermost rectifying section, or, if correspondingly subdivided, into its base section. When the argon column is correspondingly divided, especially below the lowermost rectifying section, the upper gas of the base section of the argon column is fed into the upper section of the argon column. If the argon column is correspondingly divided, especially above the uppermost rectification section, the sump liquid from the upper section of the argon column is fed into the base section of the argon column, in particular a pump is used for this purpose.

The terms "base section" and "top section" mean, in each case, the lower or upper section of a conventional one-part column, correspondingly divided and thus functional, especially with regard to the fractionation or flow occurring therein. It represents a section of the column designed into two corresponding parts. The base section has, for example, a sump tank and the upper section has, for example, an upper condenser. The upper section is therefore that part of the column connected to the corresponding condenser, and the return flow is supplied to the corresponding column. In the low-pressure columns of known air separation plants of one-piece design, an oxygen-enriched liquid fraction is obtained in the sump, which can be withdrawn as oxygen product. Accordingly, this is also carried out in the sump or lower area of the base section of the low pressure column, which is designed in two parts. Thus, if equipped accordingly, gaseous nitrogen product or so-called impure nitrogen can be withdrawn from the top of the one-part low pressure column of a known air separation plant. The same applies to the upper area of the upper section of the low pressure column, which is designed in two parts. From the top of a single-piece argon column (for the term “argon column”, see explanation above), and thus in the upper region of the upper section of a two-piece argon column, from the sump of a single-piece argon column, and thus 2 -A crude argon stream or argon product stream is withdrawn from the lower region of the base section of the partial argon column and the resulting sump product is fed back into the low pressure column.

In the context of the invention, the division of the low-pressure column into an upper section and a base section is carried out in particular above the so-called oxygen section. As explained with reference to Figure 2.4A in Haring's literature (supra), argon is present in the atmosphere in amounts of less than 1 mole %, but it has a strong influence on the concentration profile in the low pressure column. The separation in the lowermost rectification section of the low pressure column, which typically contains 30 to 80 theoretical or practical plates, can therefore be regarded as a true two-way separation between oxygen and argon. This rectification section is the oxygen section mentioned. Starting simply from the splitting carried out at the point of discharge for the gas passing into the crude argon column or above the oxygen section according to the invention, the separation is a three-way separation of nitrogen, oxygen and argon in several theoretical or practical plates. It changes.

As used herein, the term "rectification section" means any section within a subcolumn of a rectification column or multi-part rectification column designed for this purpose and configured to carry out rectification, in particular a corresponding mass transfer such as separator plates or ordered or disordered packing. It refers to having a structure. In particular, a fluid outlet or inlet, for example a side outlet, may be provided between the rectifying sections. Below (functionally) the lowermost rectifying region, the “base” of the rectifying column is located “on top” of the (functionally) upper rectifying region.

The invention generally provides a plant for low-temperature separation of air, having a rectification column system with a high-pressure column, a low-pressure column and an argon column, as well as a cold box system with a first cold box, a second cold box and a third cold box. suggest. Additional cold boxes are possible, for example a total of four cold boxes, where the low pressure column is divided into at least a base section and an upper section and a main heat exchanger box can additionally be provided.

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

Optionally, in the context of the present invention, the argon column can likewise be divided into at least a base section and an upper section, wherein the base section and the upper section of the argon column are orthogonal projections of the base section of the argon column onto the mentioned horizontal plane. They are arranged side by side in such a way that they do not overlap with the orthogonal projection of the upper section of the argon column onto the horizontal plane. In particular, there is a cross-sectional plane that intersects 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 onto the horizontal plane overlaps the orthogonal projection of the base section of the low pressure column onto the horizontal plane, The longitudinal axes of the base sections of the high-pressure column and the low-pressure column lie in particular along a common major axis, or there is a vertical axis that intersects the base sections of the high-pressure column and the low-pressure column.

In the context of the invention, the high-pressure column is arranged together with the base section of the low-pressure column in a first cold box, and the upper section of the low-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 portions of the argon column are contained in a third cold box. As a further alternative, there are separate boxes for the base and top sections of the argon column.

The arrangement proposed according to the invention results in simple constructability with particularly small transport dimensions and enables the lowest possible box height (not higher than a church tower or near an airport...). “Cold plant part” is understood here to mean a device or device part that is operated at low temperatures, especially below -50° C. during the normal operation of the plant.

In one embodiment of the invention, where 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 upper section of the argon column can be arranged in particular in the second cold box, or Vice versa, ie 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 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 a first cold box or a second cold box, in particular in the case of a corresponding embodiment or subdivision, in a cold box in which the upper section of the argon column is arranged as a crude argon column. there is.

In the present invention, the pure oxygen column is arranged in one of the 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 such that the orthogonal projection of the upper portion of the pure oxygen column or pure oxygen column onto the horizontal plane is such that the argon column or first section of the argon column onto the horizontal plane is They are arranged side by side in the plant used according to the invention, so as not to intersect the orthogonal projection of the 1 section. The upper part may be that part of the pure oxygen column that is not occupied by a sump evaporator arranged in the sump of the pure oxygen column. Due to its dimensioning, the latter can also occupy a space significantly larger in cross section than the upper part of the pure oxygen column and can optionally be arranged eccentrically (with respect to the central axis of the upper part). In this case, the orthogonal projection of the lower part of the pure oxygen column with sump evaporator onto the horizontal plane may also partially overlap the orthogonal projection of the base section of the argon column onto the horizontal plane.

Moreover, the upper section of the low-pressure column and the pure oxygen column or the upper section of the pure oxygen column preferably have at least an orthogonal projection of the pure oxygen column or the upper section of the pure oxygen column onto the horizontal plane. They are arranged side by side in such a way that they do not overlap with the orthogonal projection of the upper section or the first section of the argon column.

In other words, as already mentioned, if present in the corresponding embodiment, the pure oxygen column is supplied at the feed point with a first delivery liquid, which is removed from the argon column or its base section at the extraction point. Accordingly, the cited columns or column sections have corresponding extraction and feed points. As mentioned, the extraction point from the argon column or its base section is in particular above the rectification section and serves to release the hydrocarbons. The extraction points for the first delivery liquid are in particular the sump of the argon column or 1 to 30 theoretical plates above the base section of the argon column.

Accordingly, the first delivery liquid delivered into the pure oxygen column in particular has an oxygen content of 50 to 95 mole %, an argon content of 10 to 50 percent and a nitrogen content of 0.1 ppm to 500 ppm, preferably 0.1 ppm to 100 ppm. and the content of other components with a higher boiling point than oxygen is 0.01 ppb to 25 ppm.

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

In one embodiment of the invention with a correspondingly divided argon column, the base section of the argon column is supplied with a second delivery liquid at a feed point located in the base section of the argon column, in particular below the lowermost rectification section, this delivery It is particularly provided that the liquid is discharged from the upper section of the low-pressure column at an extraction point located in the upper section of the low-pressure column, in particular below the lowest rectifying section. Accordingly, the cited columns or column sections have corresponding extraction and feed points.

In this embodiment, the upper section of the low-pressure column and the base section of the argon column have an extraction point for the second delivery liquid from the upper section of the low-pressure column geodesically supplying additional delivery liquid into the base section of the argon column. It can be arranged in such a way that it is above a point. 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, using only one (i.e. common) pump, ideally with a redundant design. This can be fed back to the base section of the low pressure column.

Preferably, the empty section is arranged in the argon column or its base section. The hollow section is located inside the shell of the column and extends across the vertical subarea of the column. The empty section has no mass transfer elements and therefore has no effect on mass transfer. At first glance, it seems counterproductive to provide such sections, since the column shell is more expensive. However, in the context of exchanging one or more transfer fluids, it is operative in the present invention to place the mass transfer area of the upper section of the low pressure column relatively high (above the empty section) and the sump relatively low (below the empty section). It's very convenient. In particular, the empty section is arranged in the lower region of the column, especially directly above the lower end of the column shell.

If the corresponding system has a subcooling heat exchanger, this can be arranged in one of the cold boxes. In the embodiment just described, the subcooling heat exchanger can be arranged in particular under the upper section of the low pressure column.

Therefore, in this embodiment of the invention, it may be particularly provided that the upper section of the low pressure column is arranged geodically above the subcooling heat exchanger. If the sump liquid of the upper section of the low pressure column is to be able to drain from the base section of the argon column into the sump and from above the corresponding rectification section into the pure oxygen column, it must be positioned sufficiently high. In this case, the sump of the base section of the argon column may be extended downward by a so-called “blank”, i.e. an empty area or empty section, such that, in a corresponding embodiment, liquid flows from the upper section of the low-pressure column to the base of the argon column. At the same time, it can be ensured that it can be discharged into the sump of the section. 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.

Alternatively to the embodiment just mentioned, in the upper section of the low pressure column, in particular at a feed point located below the lowermost rectification section in the upper section of the low pressure column, in particular in the base section of the argon column, an extract located below the lowermost rectification section. It may also be stipulated that a second delivery liquid is supplied, at which point it is removed from the base section of the argon column. Accordingly, the cited columns or column sections have corresponding extraction and feed points. In this embodiment, the base section of the argon column and the upper section of the low-pressure column have an extraction point for additional delivery liquid from the base section of the argon column geotically supplying additional delivery liquid into the upper section of the low-pressure column. It is arranged so that it is above a point. In this way, the sump liquid in the low pressure column and the sump liquid in the base section of the argon column can be combined in the upper section of the low pressure column and returned to the base section of the low pressure column by only one pump.

In a corresponding system with a subcooling heat exchanger, this heat exchanger can in particular be arranged under the base section of the argon column in the embodiment just described.

In particular, the upper section of the low pressure column and the upper section of the argon column are side by side in such a way that the orthogonal projection of the upper section of the low pressure column onto the horizontal plane does not overlap the orthogonal projection of the upper section of the argon column onto the horizontal plane. Arrangement can be specified. There is thus a cross-sectional plane that intersects the upper section of the low pressure column and the upper section of the argon column.

In the context of the invention, a cold box height of between 35 and 50 meters, in particular approximately 43 meters, can be maintained. The high-pressure column may in particular have a height of 15 to 30 meters, in particular 25.8 meters, and the base section of the low-pressure column may in particular have a height of 7 to 20 meters, for example 14.8 meters. The height of the base section of the low pressure column is defined in particular from the height of the main condenser and the separation device accommodated therein and from the height of the so-called oxygen section, both of which are in particular between 5 and 14 meters, for example 7.4 meters. The diameter may in particular be between 1.5 and 4 meters, for example approximately 2.8 meters. The base section of the argon column has a height of, for example, 25 to 45 meters, especially approximately 39 meters.

The upper section of the low pressure column may in particular have a height of 18 to 30 meters, for example 23 meters (2.4 to 3 meters, for example about 2.6 meters in diameter) or 25 to 30 meters, for example about 27 meters in height (1.2 to 4.0 meters, for example, with a diameter of about 2.45 meters). The dimensions depend inter alia on the packing density used. The upper section of the argon column can have convenient dimension settings.

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

As in known systems, 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 connected in particular to a common column shell or to several shell-connected column shells, In particular it is arranged in the form of a known Linde double column (without the upper section of the low pressure column).

Subcooling heat exchangers, especially when mounted upright, may have vertical space requirements of up to 45 meters, for example approximately 8 metres. If the upper section of the argon column includes a corresponding upper condenser (crude argon condenser), this typically has a height of 30 to 40 m, as does the base section of the argon column. The above-described arrangement variants for the subcooling heat exchanger are particularly advantageous because they relate to a space-saving arrangement. Other arrangement variants of the subcooling heat exchanger may also be advantageous, for example in heat exchanger boxes.

(A) A pure oxygen column is such that the orthogonal projection of at least the upper portion of the pure oxygen column (for reasons and further explanation, see above) onto the horizontal plane is the orthogonal projection of the high pressure column onto the horizontal plane and the orthogonal projection of the high pressure column onto the horizontal plane. The high pressure column, the base section of the low pressure column and the base of the argon column (with corresponding details) in the first cold box, so as not to overlap with the orthogonal projection of the base section of the low pressure column as well as the orthogonal projection of the base section of the argon column. Can be arranged next to sections. This minimizes the connection pipeline.

If this arrangement (A) can no longer be transported due to its dimensions, the HDS can be relocated together with the lower part of the LDS in a separate box. Ideally, the upper part of the low pressure column is in a second cold box together with the argon column. The reboiler of the pure oxygen column is located in the shadow of the low pressure column and can be arranged asymmetrically. The argon column or section thereof is arranged in the third cold box. Height arrangement is important here.

In the context of the present invention, the base section of the argon column (with its corresponding details) can be set up to separate out high-boiling components as well as other impurities, in particular also to avoid concentration.

In the context of the invention, in particular the lower region of the upper section of the low-pressure column and the lower region of the base section of the argon column (with corresponding divisions) can be fluidically coupled to the upper region of the base section of the low-pressure column via a pump. there is.

For purposes of explanation only, the plant proposed according to the invention advantageously comprises means configured to supply cooled compressed air to the high pressure column, means configured to supply fluid from the high pressure column to the low pressure column, and means configured to supply fluid from the low pressure column. It should be mentioned again that it has means adapted to supply argon to the column.

Finally, the invention also extends to methods for low-temperature separation of air; For their features, explicit reference is made to the corresponding independent claims. In particular, the plant is used in the same manner as previously described in different embodiments. For the features and advantages of the proposed method and possible embodiments, explicit reference is made to the description of the plant according to the invention.

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

1 illustrates, in the form of a simplified process flow diagram, a plant for low-temperature separation of air that may be based on an embodiment of the invention.
Figure 2 illustrates, in side view and in a simplified representation, the arrangement of components of a plant designed according to an embodiment of the invention for low-temperature separation of air.
Figure 3 illustrates, in plan view and simplified representation, the arrangement of components of a plant designed according to an embodiment of the invention for low-temperature separation of air.
Figure 4 shows a variation of Figure 2, where an empty section is used.
Where components of a plant for low-temperature separation of air (hereinafter also referred to as “air separation plant”) are described below, the corresponding description also applies to the method carried out by it and vice versa.

Figure 1 schematically shows an air separation plant set up to obtain an argon product and a pure oxygen product, denoted throughout as 100.

The air separation plant (100) consists of a high pressure column (11), a low pressure column divided into a base section (12) and an upper section (13), and (crude) argon also divided into a base section (14) and an upper section (15). column, and a rectification column system (10) comprising a pure argon column (20). The pure oxygen column is labeled 18. The block marked with 1 comprises the customary components present in air separation plants of the exemplified type for compression, purification and cooling of feed air, in particular a main heat exchanger of a type also known. The subcooling heat exchanger is denoted as 17.

The base section 12 and top section 13 of the low pressure column and the base section 14 and top section 15 of the argon column are structurally separate from each other and arranged next to each other in the sense described above. 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. Accordingly, the base section 12 and top section 13 of the high pressure column 11 and the low pressure column are an argon system consisting of the base section 14 and top section 15 of the argon column and the pure argon column 20. connected, forming a rectification column system for nitrogen-oxygen separation of a type known per se.

In the exemplary embodiment shown, cooled, compressed feed air in the form of two material flows (a, b) is supplied into the upper section 13 of the high pressure column 11 or the low pressure column. Air separation plant 100 may be designed for internal compression and may be designed as desired in the frame shown herein. The additionally compressed feed air is passed in the form of a material stream (c) through a sump evaporator, not otherwise indicated, of the pure oxygen column 18 and is at least partially condensed, and then likewise in the upper section of the low pressure column ( 13) It is supplied internally. The specific type of air supply into the column arrangement is not essential to the invention and can be designed in any desired manner (with or without choked flow, with or without air supply into the low pressure column or its upper section 13, etc.). there is. This also applies to the provision of turbines for low temperature generation, which may or may not be provided.

The base section 12 of the high-pressure column 11 and the low-pressure column are connected via a condenser-evaporator 19, the so-called main condenser, to exchange heat and are designed as a structural unit. However, in principle the invention can also be used in systems where the high pressure column 11 and the low pressure column (or its base section 12) are arranged separately from each other and have a separate condenser evaporator 19, i.e. not integrated within the column. there is.

The operation of the air separation plant 100 is directly apparent from the representation according to FIG. 1 . Accordingly, reference is made to the technical literature cited initially.

In particular, the base section 12 and the upper section 13 of the low-pressure column are configured such that in this case the head gas flows from the upper region of the base section 12 of the low-pressure column to the upper section of the low-pressure column in the form of a material flow e. They are fluidly coupled to each other in that they are delivered to the lower area of 13). As also explained with reference to Figure 2, the arrangement of the upper section 13 of the low pressure column and the base section 14 of the argon column in the example shown is such that the sump liquid in the form of material flow f flows to the upper section of the low pressure column. allowing to flow from the lower region of the section 13 to the lower region of the base section 14 of the argon column, and an additional part of the upper gas also flows into the base section 12 of the low pressure column in the form of material flow g. supplied from the upper region. In this way, the sump liquid is collected from the upper section 13 of the low pressure column and the base section 14 of the argon column in the sump of the base section 14 of the argon column and the material flow h by means of a common pump 110. It can be pumped back into the upper region of the base section 12 of the low pressure column in the form of. As mentioned, a reverse arrangement is also possible.

The upper gas of the base section 14 of the argon column is passed into the lower region of the upper section 15 of the argon column, whereby the liquid is pumped back by the pump 120. The integration of a pure argon column 20 can substantially correspond to what is routine in the art. Accordingly, the argon column consisting of the base section 14 and the top section 15 is fluidly connected in parallel to the low pressure column or its base section 12 and top section 13, so that the base section 12 of the low pressure column The corresponding upper gas from the upper region is also delivered into the lower region of the base section 14 of the argon column, and the sump liquid is transferred from the lower region of the base section 14 of the argon column to the lower region of the base section 12 of the low pressure column. returns to the upper area. In particular, the same pump is used which is also used to return the sump liquid from the lower region of the upper section 13 of the low pressure column into the upper region of the base section 12 of the low pressure column.

In addition, the base section 14 and the upper section 15 of the argon column allow the upper gas to pass from the upper region of the base section 14 of the argon column into the lower region of the upper section 15 of the argon column, (additional of) are fluidically coupled to each other in that by means of the pump the sump liquid is recycled from the lower region of the upper section 15 of the argon column into the upper region of the base section 14 of the argon column.

Here the pure oxygen column 18 is supplied at a feed point 18a with a delivery liquid in the form of a material flow t removed from the base section 14 of the argon column at the extraction point 14a. The base section 14 of the pure oxygen column 18 and the argon column are such that the extraction point 14a for the delivery liquid from the base section 14 of the argon column is geodetic to the delivery liquid into the pure oxygen column 18. It is arranged in such a way that it is above the feed point 18a for the column, so that the delivery liquid can be delivered into the pure oxygen column 18 without a pump.

In the base section 14 of the argon column, additional delivery liquid in the form of the already mentioned material flow f, removed at the extraction point 13b from the upper section 13 of the low pressure column, is added at the feed point 14b. supplied, in the example illustrated herein the upper section 13 of the low pressure column and the base section 14 of the argon column provide an extraction point 13b for further transfer liquid from the upper section 13 of the low pressure column. It is arranged in such a way that it is above the supply point 14b for further delivery liquid into the base section 14 of the argon column.

The integration of the components of the air separation plant 100 into a cold box is illustrated in the form of a simplified side view in Figure 2, where the components of the air separation plant 100 are identical to those described above with respect to Figure 1. Indicated by reference signs. As shown in Figure 1, these are shown in side view but simplified to a much greater extent. The fluid connections are not shown, but are obvious correspondingly to the representation according to FIG. 1 . As described below, two cold boxes 110, 120 are illustrated that house and insulate the components of the air separation plant 100.

The base section 12 and the upper section 13 of the low pressure column are in this case such that the orthogonal projection of the base section 12 of the low pressure column onto the horizontal plane H is of the low pressure column onto the horizontal plane H. Arranged next to each other in such a way that they do not overlap the orthogonal projection of the upper section 13, the base section 14 and the upper section 15 of the argon column are likewise the base section of the argon column on the horizontal plane H. They are arranged side by side in such a way that the orthogonal projection of (14) does not overlap with the orthogonal projection of the upper section (15) of the argon column onto the horizontal plane (H).

In contrast, the high pressure column 11 is a low pressure column such that the orthogonal projection of the high pressure column 11 onto the horizontal plane H overlaps the orthogonal projection of the base section 12 of the low pressure column onto the horizontal plane H. It is arranged below the base section 12 of.

The base section 14 of the pure oxygen column 18 and the argon column is such that an orthogonal projection of at least one upper portion of the pure oxygen column 18 (described further above) onto the horizontal plane H is the horizontal plane H. (H) are arranged side by side so as not to overlap with the orthogonal projection of the base section 14 of the argon column onto the image.

Additionally, in the air separation plant 100, the upper section 13 of the low-pressure column and the upper section 15 of the argon column are such that the orthogonal projection of the upper section 13 of the low-pressure column onto the horizontal plane H is horizontal. They are arranged side by side in such a way as to overlap the orthogonal projection of the upper section 15 of the argon column onto the 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 and the pure oxygen column 18 are arranged in the first cold box 110, and the upper section 13 of the low-pressure column and the upper section 15 of the argon column is arranged in the second cold box 120 as well as the pure argon column 20. This leads to the advantages of the corresponding embodiments according to the invention.

As illustrated herein by the dotted line, the subcooling heat exchanger 17 is formed, in particular, by an orthogonal projection of the subcooling heat exchanger 17 onto a horizontal plane H, especially at the top of the low pressure column onto this horizontal plane H. It may be arranged below the upper section 13 of the low pressure column in the second cold box 120 so as to overlap the orthogonal projection of the section 13 .

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

Figure 3 shows the components shown in Figure 2 in plan view, where the horizontal plane H lies parallel to the paper plane, with explicit reference to the description associated with Figure 2 for further details.

Figure 4 corresponds to Figure 2 except for the empty 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 empty section 14a shown in dashed lines). Only on the empty area 14a is a mass transfer element such as structured packing installed. Liquid falls from the lower end of the mass transfer element through the empty section into the column sump at the lower end of empty section 14a.

Claims (12)

A plant (100) for low-temperature separation of air, comprising:
- 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),
- the pure oxygen column (18) and the argon column or the base section (14) of the argon column (14, 15) of the at least one upper part of the pure oxygen column (18) on the horizontal plane (H). arranged side by side so that the orthogonal projection does not overlap with the orthogonal projection of the argon column (14, 15) or the base section (14) of the argon column (14, 15) onto the horizontal plane (H),
- the pure oxygen column (18) has a feed point (18a) for the first delivery liquid and the argon column (14, 15) or the base section (14) of the argon column (14, 15) has a feed point (18a) for the first delivery liquid. Having an extraction point 14a for the delivery liquid, the base sections of the pure oxygen column 18 and the argon columns 14, 15 are positioned such that the extraction point 14a for the first delivery liquid is geodetic. 1. A plant (100) arranged to be above the supply point (18a) for the first delivery liquid,
- the low pressure columns (12, 13) are divided into at least a base section (12) and an upper section (13),
- the base section 12 and the upper section 13 of the low pressure columns 12, 13 are orthogonal to the base section 12 of the low pressure columns 12, 13 on the horizontal plane H. arranged next to each other in such a way that the projection does not intersect the orthogonal projection of the upper section (13) of the low pressure column (12, 13) onto the horizontal plane (H),
- the high-pressure column (11) is such that the orthogonal projection of the high-pressure column (11) onto the horizontal plane (H) is such that the base section (12) of the low-pressure column (12, 13) onto the horizontal plane (H) arranged below the base section (12) of the low pressure column (12, 13) in such a way that it intersects the orthogonal projection of
- the pure oxygen column (18) and the argon column (14, 15) or the base section (14) of the argon column (14, 15) extends the pure oxygen column (18) onto the horizontal plane (H). so that the orthogonal projection of at least one upper part of does not overlap with the orthogonal projection of the argon column (14, 15) or the base section (14) of the argon column (14, 15) onto the horizontal plane (H). arranged side by side,
- 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 in the first cold box (110) together with the base section (12) of the low pressure columns (12, 13),
- the upper section (13) of the low pressure column (12, 13) is arranged in the second cold box (120),
- the argon column (14, 15) or one or more sections of the argon column (14, 15) are arranged in the third cold box (130),
- Plant (100), characterized in that the pure oxygen column (18) is arranged in the second cold box. 2. The method according to claim 1, wherein the argon column (14, 15) is divided into at least a base section (14) and an upper section (15), the base section (14) and the upper section of the argon column (14, 15) (15) is such that the orthogonal projection of the base section 14 of the argon column 14, 15 onto the horizontal plane H is the orthogonal projection of the upper section 15 of the argon column 14, 15. Plants 100, arranged next to each other in such a way that they do not intersect. The method according to claim 1 or 2, wherein the argon columns (14, 15) are designed as crude argon columns and are further provided with a pure argon column (20), wherein the pure argon column (20) is arranged in a first cold box (110) or in a second cold box (120), in which the upper section (15) of the argon column (14, 15), especially designed as a crude argon column, is arranged, Plant (100). 4. The method according to any one of claims 1 to 3, wherein the extraction points (14a) for the first delivery liquid comprise 1 to 30 theoretical plates above the sump of the base section of the argon column (14, 15). Phosphorus, plant (100). 5. The method according to any one of claims 1 to 4, wherein the base section (14) of the argon column (14, 15) has a feed point (14b) for a second delivery liquid, and the low pressure column (12, The upper section 13 of 13) has an extraction point 13b for the second delivery liquid, the upper section 13 of the low pressure column 12, 13 and the argon column 14, 15. Plant (100), wherein the base section (14) is arranged such that the extraction point (13b) for the second delivery liquid is above the supply point (14b) for the second delivery liquid. Plant (100) according to any one of claims 1 to 5, wherein an empty section (13a) of the argon column (14, 15) or in the base section (14) of the argon column is arranged. 7. The method according to any one of claims 1 to 6, in the first cold box (110) or in the second cold box (120), especially below the upper section (13) of the low pressure column (12, 13). A plant (100) with a subcooling heat exchanger (17) arranged in the second cold box (120). 8. The argon column (14, The base section 14 of 15) has an extraction point 14c for the second delivery liquid, the base section 14 of the argon columns 14, 15 and the low pressure columns 12, 13. Plant (100), wherein the upper section (13) is arranged in such a way that the extraction point (14c) for the second delivery liquid is above the supply point (13c) for the second delivery liquid. 9. Plant (100) according to claim 8, having a subcooling heat exchanger (17) arranged below the base section (14) of the argon column (14, 15). 10. Plant according to any one of claims 1 to 9, wherein all low temperature device parts are arranged in the first cold box (110) or the second cold box (120) and the third cold box is not used. . 11. Plant according to any one of the preceding claims, wherein the first section (14) of the crude argon column (14, 15) is formed by its base section. Method for low-temperature separation of air, wherein a plant (100) according to any one of claims 1 to 11 is used.