EP3614082A1 - Air separation plant, method for cryogenic decomposition of air and method for creating an air separation system - Google Patents

Abstract

The present invention relates to an air separation plant (100-700) with four separation units (1-4) in the form of a high-pressure column (1), a foot section (2) of a two-part low-pressure column, the head section (3) of the two-part low-pressure column and a one-part Argon recovery column (4), the four separation units (1-4) being connected to one another and / or to one or more further apparatuses (7, 8) at least in part by means of lines (6), the lines (6) being one or more comprising first lines and a plurality of second lines, the one or more first lines comprising one or more lines which open into a head region of the foot section (2) of the low pressure column and / or a line which leads into a gas space of a head condenser (5a) Argon recovery column (4) opens, is or are. It is provided that vertically running sections of the second lines are at least partially accommodated in a cold box (20a, 40, 40a), which is designed as a column gold box (20a) in which the head section (3) of the low-pressure column is arranged, or as a separate line gold box (40, 40a) in which none of the four separation units (1-4) is arranged. A corresponding method for the low-temperature separation of air and a method for creating a corresponding air separation plant (100-700) are also the subject of the present invention.

Description

The present invention relates to an air separation plant, a method for the low-temperature separation of air by means of a corresponding air separation plant and a method for the construction of a corresponding air separation plant.

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, for example, at H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH, 2006, in particular Section 2.2.5, "Cryogenic Rectification ", described.

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 the production of nitrogen and / or oxygen in the liquid and / or gaseous state, that is to say the rectification columns for the nitrogen-oxygen separation, rectification columns for the production of 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 level of 4 to 7 bar, in particular approximately 5.3 bar. The low pressure column is operated at a pressure level of typically 1 to 2 bar, in particular approximately 1.4 bar. In certain cases, higher pressure levels can also be used in the low pressure column. The pressures specified here and below are absolute pressures at the top of the columns specified.

In known methods 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. This liquid, which in particular also contains argon, is at least partly 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, where it is possible for evaporated and unevaporated portions to be fed into the low-pressure column at different positions.

The present invention is based on a method or a corresponding system in which a high and a low pressure column is used. In the context of the present invention, however, the low-pressure column is not formed in one piece, but is divided into a first section and a second section, the first and the second section being arranged at different positions of the air separation plant and at different heights, and in particular not in a plan view of a longitudinal column axis project onto each other. However, the first and the second section of the low pressure column are operated at a common pressure level within the scope of the present invention. The low-pressure column used in the context of the present invention, which is divided into two sections, differs from also known arrangements, in which, in addition to the high-pressure and low-pressure column, a further column for separating nitrogen and oxygen is provided, which, however, is operated at a pressure level, that lies between the pressure levels at which the high pressure column and the low pressure column are operated.

Air separation plants with raw and pure argon columns can be used to obtain 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 at a certain height in the low-pressure column in corresponding plants. At this or at another convenient point, possibly also below the argon maximum, argon-enriched gas with an argon concentration of typically 5 to 15 mole percent can be withdrawn 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 are only typical example values.

The crude argon column essentially serves to separate the oxygen from the gas drawn off from the low-pressure column. The separated oxygen in the crude argon column or a corresponding oxygen-rich fluid can be returned to the low-pressure column in liquid form. The oxygen or the oxygen-rich fluid is typically fed into the low-pressure column a number of theoretical or practical trays below the feed point for the liquid which has been drawn off from the high-pressure column, enriched with oxygen and depleted with nitrogen and possibly at least partially evaporated. A gaseous fraction which remains in the crude argon column and essentially contains argon and nitrogen is separated further 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 liquid which has been drawn off from the high-pressure column and enriched with oxygen and nitrogen and 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, it being 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 typically withdrawn from the raw argon column or a comparable column somewhat further below the fluid conventionally transferred into the pure argon column, the bottoms in the section between the raw argon condenser, i.e. the top condenser of the raw argon column, and a corresponding deduction serve in particular as barrier bottoms 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 the production of pure argon and not for the production of crude argon, the term “argon production column” is also used below. An argon recovery column can be a conventional one Raw argon column (which is used with or without pure argon column) or a corresponding raw argon column modified for obtaining pure argon. When creating air separation plants that are set up for argon extraction, problems arise due to the dimensions of the columns used. A double column system for nitrogen-oxygen separation of conventional type can reach a height of almost 75 m. Corresponding air separation plants can therefore no longer be prefabricated because the respective component groups can generally no longer be transported over longer distances. This means that they have to be created at the respective destination. This is disadvantageous for various reasons, among other things because appropriate personnel at the destination are either unavailable or expensive. The effort to create appropriate air separation plants increases significantly.

However, it is desirable to have a largely modularized air separation plant at the manufacturing site. The individual components are preferably already accommodated there in the corresponding cold boxes and only have to be connected to one another at the destination. Modules, so-called piping skids, can advantageously also be used for this.

Disclosure of the invention

Against this background, the present invention proposes an air separation plant, a method for the low-temperature separation of air by means of a corresponding air separation plant and a method for building a corresponding air separation plant with the features of the independent claims. Preferred embodiments are the subject of the dependent claims and the following description.

Before the features and advantages of the present invention are explained, some basics of the present invention are explained in more detail and terms used below are defined.

The devices used in an air separation plant are described in the cited technical literature, for example by Haering (see above) in Section 2.2.5.6, "Apparatus". Unless the following definitions differ, therefore expressly refer to the cited technical literature for the language used in the context of the present application.

Liquids and gases can, in the language used here, be rich or poor in one or more components, "rich" for a content of at least 50%, 75%, 90%, 95%, 99%, 99.5%, 99, 9% or 99.99% and "poor" for a maximum of 50%, 25%, 10%, 5%, 1%, 0.1% or 0.01% on a mole, weight or volume basis , The term "predominantly" can correspond to the definition of "rich". Liquids and gases can also be enriched or depleted in one or more components, these terms refer to a content in a starting liquid or gas from which the liquid or gas was obtained. The liquid or gas is "enriched" if it contains 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 contains at most 0.9 times, 0.5 times, 0.1 times, 0.01 times or 0.001 times the content of a corresponding component, based on the starting liquid or the starting gas. If, for example, "oxygen", "nitrogen" or "argon" is mentioned here, this should also be understood to mean a liquid or a gas which is rich in oxygen or nitrogen, but does not necessarily have to consist exclusively of it.

The present application uses the terms “pressure level” and “temperature level” to characterize pressures and temperatures, which is intended to express that corresponding pressures and temperatures in a corresponding system do not have to be used in the form of exact pressure or temperature values to realize the inventive concept. However, such pressures and temperatures are typically in certain ranges, for example ± 1%, 5%, 10%, 20% or even 50% around an average. Corresponding pressure levels and temperature levels can lie in disjoint areas or in areas that overlap one another. In particular, pressure levels include, for example, unavoidable or expected pressure drops. The same applies to temperature levels. The pressure levels given here in bar are absolute pressures.

The high-pressure column and the low-pressure column (or, in the context of the present invention, its first section) of an air separation plant are in heat-exchanging connection via a so-called “main condenser”. The main condenser can in particular be arranged in a lower (sump) area of the low-pressure column (or its first section thereof). In this case, it is a so-called internal main condenser and the evaporation space of the main condenser is also the interior of the low-pressure column (or of its first section). However, the main condenser can basically be arranged outside the interior of the high-pressure column, that is to say a so-called external main condenser.

A rectification column system of an air separation plant is arranged in one or more cold boxes. A “cold box” is understood here to mean an insulating covering which completely encompasses a heat-insulated interior space with outer walls, except for bushings for lines and the like. Plant parts to be insulated are arranged in the interior, for example one or more rectification columns and / or heat exchangers. The insulating effect can be brought about by appropriate design of the outer walls and / or by filling the space between the system parts and outer walls with an insulating material. In the latter variant, a powdery material such as pearlite is preferably used. Both the rectification column system of a plant for the low-temperature separation of air and the main heat exchanger and other cold plant parts such as pipes, valves and instrumentation are typically enclosed by one or more cold boxes. The external dimensions of the cold box usually determine the transport dimensions.

A "main heat exchanger" of an air separation plant is used to cool the feed air in indirect heat exchange with return flows from the rectification column system. It can be formed from a single or a plurality of heat exchanger sections connected in parallel and / or in series, for example from one or more plate heat exchanger blocks. Separate heat exchangers, which are used specifically for the evaporation or pseudo-evaporation of a single liquid or supercritical fluid, without heating and / or evaporation of another fluid, are not part of the main heat exchanger.

A "subcooler" or "subcooling counterflow" in the parlance used here is a heat exchanger through which gaseous and liquid material flows are subjected to heat exchange in an air separation plant, which are removed from the rectification column system and at least partially returned to the rectification column system after the heat exchange ,

The relative spatial terms "above", "below", "above", "below", "above", "below", "beside", "side by side", "vertically", "horizontally" etc. refer here to the spatial orientation of the rectification columns of an air separation plant in normal operation. An arrangement of two rectification columns or other components "one above the other" is understood here to mean that the upper end of the lower of the two parts of the apparatus is at a lower or the same geodetic height as the lower end of the upper of the two parts of the apparatus and the projections of the two parts of the apparatus are in one intersect horizontal plane. In particular, the two parts of the apparatus are arranged exactly one above the other, that is to say the axes of the two parts of the apparatus run on the same vertical straight line. However, the axes of the two parts of the device do not have to lie exactly vertically one above the other, but can also be offset from one another, especially if one of the two parts of the device, for example a rectification column or a column part with a smaller diameter, is to have the same distance from the sheet metal jacket of a cold box as another with a larger one Diameter.

Advantages of the invention

The present invention is based on the knowledge that a specific arrangement of different rectification columns or of sections of corresponding rectification columns in different cold boxes and, in particular, their advantageous dimensioning and / or subdivision allows, in certain cases, corresponding cold boxes with the rectification columns contained therein or the respectively contained ones Prepare sections of rectification columns (hereinafter also generally referred to as "separation units") and transport them in a prefabricated state to the place of manufacture of an appropriate air separation plant. In certain embodiments of the present invention, corresponding units can be completely prefabricated; however, it is in other configurations also possible to prefabricate only the part of the cold boxes that can be provided with the appropriate transport dimensions and to transport them to the place of manufacture, whereas other components of a corresponding air separation plant are manufactured on site. Any combination of prefabrication and on-site production is possible. A particular advantage in the context of the present invention results from advantageous arrangement options for part of the lines of a corresponding system.

Overall, the present invention proposes an air separation plant with four separation units in the form of a high-pressure column (first separation unit), a foot section of a two-part low-pressure column (second separation unit), the head section of the two-part low-pressure column (third separation unit) and a one-part argon recovery column (fourth separation unit) before, the four separation units being connected at least in part by means of lines to one another and / or to one or more further apparatuses.

The argon recovery column can be designed, in particular, as a conventional crude argon column, in which case a component mixture referred to as crude argon in customary usage is removed. However, the argon recovery column can also be a modified crude argon column, to which fluid is supplied from one or both parts of the low-pressure column, but pure argon is removed directly. In the first case, a pure argon column is typically present, in the second case, not. The other apparatuses can in particular be a main heat exchanger of the air separation plant and a subcooling counterflow. The four separation units can also be connected to one another, for example, by means of corresponding lines via such a further apparatus as a supercooling counterflow.

A "two-part" low-pressure column is understood to mean in particular a corresponding rectification column in which two sections can be arranged spatially separated from one another. In plan view, corresponding sections of a two-part rectification column do not project, or do not project completely, onto one another and, in particular, corresponding sections are also not arranged in a common outer shell. The term "two-part design" thus delimits corresponding configurations from structural units in which Components are structurally connected to one another permanently (ie not only via lines) and cannot be arranged separately from one another, as is the case here in the case of the argon recovery column.

The "foot section" and "head section" here refer to the sections of a two-part rectification column which correspond in their function, in particular with regard to the fractions or material flows occurring there, to the lowermost or uppermost sections of conventional, one-piece rectification columns. A foot section has, for example, a sump container, and a head section has, for example, a head condenser. The top section is thus the part of a corresponding rectification column, which is connected to a corresponding top condenser, and in which a return flow is applied to the corresponding rectification column. In a one-piece low-pressure column of known air separation plants, an oxygen-rich liquid fraction is obtained in the sump, which can be drawn off as an oxygen product. This also takes place in the sump of a foot section of a two-part low-pressure column. The foot section of the two-part low-pressure column is therefore also referred to as the "oxygen section". At the head of a one-piece low-pressure column of known air separation plants, a gaseous nitrogen product can be drawn off, the same applies to the upper part of a head section of a two-piece low-pressure column. The sections of a "two-part" rectification column (foot and head section) are connected to one another by means of lines and possibly pumps, in order in this way to represent an operation which is also possible with a one-part column.

In the context of the present invention, a distinction is made between the lines with regard to their arrangement in a cold box, as explained below. The lines comprise one or more first lines and several second lines, the terms “first” and “second” lines being used here only to differentiate corresponding lines with regard to the arrangement mentioned. The one or more first lines is or are one or more lines which open into a head region of the foot section of the low pressure column and in particular transport gas from the head region of the foot section of the low pressure column into a lower region of the head section of the low pressure column and / or the argon recovery column, and / or a pipe running in a gas room of an evaporation chamber of a top condenser of the argon recovery column, and which in particular corresponding gas is transported into a central region of the top section of the low pressure column. The second lines include in particular all or part of the lines mentioned above, which do not represent the first lines. These are, in particular, gas lines which are connected to the top section of the low-pressure column, and liquid lines to and from an existing supercooling counterflow. If present, the pure argon column also has a plurality of lines with a corresponding number of control valves for the reboiler and a condenser control. These can also be "second lines" in the sense used here, as can lines for an argon transport pump which may be present.

Basically, an air separation plant with cryogenic separation units of the type previously explained, but in contrast to the present invention with a two-part crude argon column, from which EP 2 965 029 B1 known. In the context of the present invention, however, it was recognized that prefabrication of corresponding cold boxes is also possible without the division of an argon recovery column such as a crude argon column and the associated additional outlay on equipment, in particular the provision of pumps for transferring fluid between the sections of such a crude argon column is. The present invention, in its different advantageous configurations explained below, also allows partial or complete prefabrication of components of a corresponding air separation plant without the need to split the crude argon column in two.

According to the invention, it is provided that vertically running sections of the second lines are at least partially accommodated in a cold box, which is used as a column cold box, in which the head section of the low-pressure column is arranged, or as a separate line cold box, in which none of the four separation units mentioned (but possibly one further separation unit is arranged as explained below) is formed. The term "column cold box" is used here to characterize a cold box which has at least one of the separation units mentioned. A "line cold box", on the other hand, preferably serves to hold corresponding lines, but can also have a further separation unit in the form of a pure argon column, as explained below.

The two alternatives of the present invention are connected to one another by the common inventive idea that a particularly advantageous arrangement of corresponding components can also be achieved in a system with a one-part argon recovery column such as a crude argon column, the present invention, in particular the smaller dimensions, according to the first alternative makes use of a head section of a low-pressure column, which can be suitably adapted for this purpose in terms of packaging, as a result of which the second lines or their named sections can be accommodated in a corresponding column cool box. Housing the second lines or their sections in a separate piping gold box also leads to the advantages which can be achieved according to the invention. By providing the second lines or their named sections in a separate cold box, i.e. using a line cold box, a larger part of the assembly work can be relocated from the construction site to the workshop, since the mentioned pillar gold box with the additional ones may be added Line sections is no longer transportable.

As mentioned, in the context of the present invention the second lines or their mentioned sections are at least partially housed in a corresponding cold box. However, one or more vertically running sections of the first line or of the plurality of first lines can also be accommodated in the cold box, in which the vertically running sections of the second lines are at least partially accommodated, if this is advantageous for manufacturing reasons, for example.

If the separate line cold box is provided, separation units and further apparatus can be arranged in different ways within the scope of the present invention, for example to ensure portability or prefabricability or, if these are not possible, advantageous production on the construction site and / or particularly space-saving To allow arrangement and / or a reduction of line lengths and the associated manufacturing costs.

In addition to the separate line gold box, a common column gold box can be provided in which all of the four separation units are accommodated. Such a common pillar gold box is typically not transportable and is therefore advantageously manufactured on the construction site. As part of this However, the separate piping gold box is provided, the piping work on the construction site can nevertheless be significantly reduced by appropriate prefabrication. In this context, further instrumentation, in particular temperature, pressure and quantity measuring devices as well as analysis points, can be relocated with corresponding advantages to this line cold box.

The embodiment of the present invention, in which all four separating units are arranged in a common pillar gold box, can, in a particularly preferred embodiment, which is explained below, in particular lead to a reduction in the steel construction effort due to the optimized surface of a common outer shell of all components.

In this embodiment, the separation units are preferably arranged in such a way that their longitudinal axes are parallel to one another, as is customary in the art. The longitudinal axes run in the direction of a maximum extension of the separation units. The longitudinal axes can coincide with the central axes of the separation units; corresponding separation units can, however, also be constructed asymmetrically. However, the separation units can be arranged at different heights in the sense of the above explanations. In the context of the present invention, in particular the high-pressure column and the foot section of the two-part low-pressure column are permanently connected to one another, in particular their column sleeves being welded to one another. Since the high pressure column typically has a smaller diameter than the low pressure column, no accommodation is typically provided in a common column jacket; the column jacket of the high-pressure column is attached to the lower side of the column jacket of the foot section of the low-pressure column.

In the context of the present invention, it is provided to arrange the line gold box and the column gold box with the four separation units in four quadrants in a projection onto a plan plane that is perpendicular to the longitudinal axes of the separation units, such that in a first of the quadrants at least the major part of the high-pressure column and the foot section of the two-part low-pressure column one above the other, in a second of the quadrants at least the major part of the head section of the low-pressure column, in a third of the Quadrants at least the majority of the argon recovery column and in a fourth of the four quadrants the line cold box are arranged. The separating units mentioned are surrounded in their respective quadrants by the common column cool box.

If we are talking about a floor plan level, this means a level on which the elements mentioned can be projected. Not all components have to be cut or present in all planes perpendicular to the longitudinal axes of the separating units; this is not the case in particular if different separating units have different heights and therefore do not extend over the entire height, or, as in the case of the high-pressure column and the foot section of the low-pressure column, these elements are arranged one above the other. In the projection onto the floor plan level, however, there are all elements, including one above the other. A "projection onto the floor plan level" corresponds to a plan view along the longitudinal axes mentioned.

If the term "quadrants" in a corresponding plane is used here, these are regions separated from one another by imaginary lines intersecting perpendicularly in the plane. These do not have to be in the form of structurally separate departments. The respective separation units can also protrude from their assigned quadrant or occupy only part of a corresponding quadrant. This is expressed in the context of this description by the fact that "at least the major part" of the respectively specified elements is arranged in a corresponding quadrant. This at least predominant part comprises in particular more than 75%, 80% or 90% of the respective base area.

In the context of the present invention, the first to fourth quadrants can be arranged in the plan view, in particular clockwise around a center point. In other words, the quadrants in which the separating units are arranged or their common pillar gold box is arranged can lie in three adjacent quarters of the floor plan level and the line gold box can be arranged in the remaining quarter.

In particular, the line gold box and the common column gold box with the separating units can be projected onto the floor plan level within one Rectangle with four side lines may be arranged, which includes a partial area of each of the quadrants, the partial area of the first and second quadrant on a first, the partial area of the second and third quadrant on a second, the partial area of the third and fourth quadrant on a third and the Subareas of the fourth and first quadrants rest on a fourth of the side lines. A first dividing line lying in the floor plan level, on the left side of which the first and the second quadrant and on the right side the third and fourth quadrant are arranged, lies between and parallel to the first and the third side line and a second line running in the floor plan level The dividing line, which is perpendicular to the first dividing line and on the left side of which is the second and third quadrant and on the right side of which are the fourth and first quadrant, lies between and parallel to the second and fourth side line. In a preferred embodiment of the invention, the rectangle can in particular also be square.

In the embodiment just explained, the separating units are arranged in their respective quadrants and the surrounding pillar gold box in an L shape, the line gold box being arranged at an inner angle of the L. In particular, the line gold box and the separating units or their common pillar gold box can be surrounded with a common outer shell, the projection of which on the plan level is limited at least in one section by the rectangle with the four side lines. In particular, however, it is also possible to surround only the separating units with a common outer shell in the form of their pillar gold box, the projection of which on the plan level is then at least in an L-shaped section, the line gold box then being arranged in an inner angle of this L outside the outer shell is.

In an air separation plant designed according to the invention, the separating units can therefore be arranged together without the line gold box in a column gold box, which has a recess in the fourth quadrant in the projection onto the floor plan level, in which the line gold box is arranged in the projection onto the floor level level. The line cold box can also have a rectangular cross section when projected onto the floor plan and can rest on the third and fourth side lines. Depending on the connection requirements, the corresponding side surfaces can be opened or closed.

In a further embodiment, in addition to the separate line gold box, a common column gold box is provided, in which the high pressure column, the foot section of the low pressure column and exactly one of the four separation units are accommodated, with another column gold box being provided in which the remaining of the four separation units is accommodated. This additional pillar gold box can in particular be prefabricated.

In addition to the separate line cold box, however, in a further embodiment of the present invention, a common column cold box can also be provided, in which (only) the high-pressure column and the foot section of the low-pressure column are accommodated, preferably in a common column jacket or in interconnected separate column jackets, a further common column cold box is provided, in which the two remaining of the four separation units are accommodated.

Instead of the further common pillar gold box, two separate pillar gold boxes can also be used. In addition to the separate line cold box, a common column cold box can be provided in which (only) the high-pressure column and the foot section of the low-pressure column, in particular in the connection mentioned, are accommodated, in which case two further column gold boxes are provided, in each of which one of the two remaining four separation units are included. As mentioned, the particular configuration is based in particular on the prefabricability and transportability and the available transport options.

In all cases, the foot section of the low-pressure column and the head section of the low-pressure column are preferably arranged next to one another at different geodetic heights and in the sense explained. In particular, a lowest point is in a column interior of the foot section of the low-pressure column above a lowest point in a column interior of the head section of the low-pressure column. The geodetic heights at which the lowest point in the column interior of the foot section of the low-pressure column on the one hand and the lowest point in the column interior of the head section of the low-pressure column are arranged on the other hand differ in particular more than the geodetic heights at which the lowest point in the column interior of the high-pressure column on the one hand and the lowest point in the column interior of the head section of the low pressure column are arranged on the other hand. As a result, the arrangement has a lower overall height than in conventional cases.

In the air separation plant proposed according to the invention, a raw argon column can be provided as the argon recovery column and a pure argon column as a fifth separation unit, wherein the pure argon column can be accommodated in the line gold box or in that of the column gold boxes, in the green argon column (in particular the green argon column and no further separation units) is. In both cases, the small size of the pure argon column, which can therefore be accommodated in a corresponding cold box, results in a particularly advantageous use of space. In particular, if the arrangement of a pure argon column in a common column gold box with the raw argon column would make it impossible to transport it, or if a corresponding column gold box as a prefabricated unit could no longer be transported even without a pure argon column, the pure argon column would advantageously be accommodated in the separate pipeline gold box, since the this can increase the level of prefabrication. As mentioned, however, the present invention can also provide pure argon extraction without a separate pure argon column. In this case, the argon recovery column is modified in the manner described and is used for the direct recovery of pure argon with a content of 100 to 0.1 ppm nitrogen and oxygen. In any case, the argon recovery column is fed with fluid from the foot or head section of the low pressure column at an appropriate pressure level.

In the air separation plant proposed according to the invention, a separation unit set up for the enrichment or extraction of a krypton / xenon or helium / neon mixture can also be provided as a fifth separation unit, this fifth separation unit being able to be accommodated in the line cold box or in that of the column cold boxes, in the crude argon column (in particular the crude argon column and no other separation units) is included. The advantages are similar to those with a corresponding arrangement of a pure argon column.

Instead of using a two-part crude argon column, as is known from the prior art, the packing density of the argon recovery column can in particular be increased within the scope of the present invention, so that it is smaller is buildable and can therefore be accommodated together with other separation units in a pillar cold box or in a separate, portable pillar gold box. In particular, a packing density of more than 750 square meters per cubic meter can be used in a corresponding argon recovery column. In this way it is possible in particular to design a corresponding pillar cool box in transportable dimensions. In the context of the present invention, a top condenser of the crude argon column is advantageously designed in such a way that a corresponding cold box becomes portable, in particular with a diameter of less than 4 meters.

The present invention makes it possible to build at least part of the piping in the form of the lines mentioned as a transportable unit, as a result of which the work on the construction site can be reduced. An air separation plant designed according to the invention can, if a separate line cold box is provided, in particular have a separate main heat exchanger gold box in which the main heat exchanger of the air separation plant is accommodated, one of the side surfaces of the line gold box assigning a side surface of the main heat exchanger gold box. In this way, the connections from the main heat exchanger to the separating units and vice versa can be accommodated at least for the most part in the line cold box and prefabricated accordingly.

In the case just explained, it is particularly advantageous if an arrangement is carried out in such a way that at least one further of the side surfaces of the line gold box each assigns a side surface to one of the column gold boxes. If a column gold box is provided which contains all of the four separation units mentioned, this is arranged in particular on the side surface of the line gold box which is opposite the side surface which the main heat exchanger cold box assigns. If several pillar gold boxes are provided, these are advantageously distributed around the line gold box. Any of the cold boxes explained can be connected to one another on their surfaces, for example to facilitate joint transport or to reduce insulation losses. In particular, side faces of a line gold box and a main heat exchanger gold box can be arranged parallel to one another, it also being possible to interpose a column gold box for one or more separation units.

If a separate line cold box is provided in an air separation plant according to the invention, it has a size of less than 6 meters, in particular less than 4.8 meters, in particular less than 4.2 meters, in particular in an extension direction. This enables easy transport taking into account typical clearance heights of bridges and the like. A corresponding separate line cold box can in particular also have a subcooling counterflow of the air separation plant. This can be arranged in a corresponding line cold box in a particularly space-saving manner. In contrast to an arrangement in a main heat exchanger cold box, as is also possible, both cold boxes (line and main heat exchanger cold box) are easier or even transportable in this way. The separate line cold box can in particular be designed in such a way that it extends in a first direction parallel to the vertically running sections of the second lines by at least a factor 1.5 greater than in the directions vertical to it. The extension in the direction parallel to the vertically running sections of the second lines is in particular more than 20 m and the extension in the directions perpendicular thereto, for example 5 m in each case.

It should be understood that the present invention relates in particular to arrangements in which the high-pressure column and the foot section of the low-pressure column form a solid structural unit with one another. In particular, the respective column jackets can be welded together. The corresponding separation units are therefore permanently and permanently connected to one another. In particular, the high-pressure column and the foot section of the low-pressure column can have the same or different cross-section, whereas the head section of the low-pressure column can in particular be designed with a smaller cross-section if a packing with a lower density is used here. This enables the already mentioned arrangement of the head section of the low-pressure column up to a certain diameter in a column cool box, which also contains corresponding sections of the second lines, in the corresponding embodiment of the invention.

Because a corresponding head section of the low pressure column typically has a lower height than an argon recovery column such as a crude argon column and / or the common unit of high pressure column and foot section of the Low pressure column, the supercooling counterflow can also be arranged in a column cool box, advantageously below the top section of the low pressure column. If the low-pressure column has a comparatively small diameter, it can be arranged, in particular, together with the second lines mentioned and the supercooling countercurrent in a corresponding column gold box. In the case of a medium diameter, the supercooling countercurrent is in particular arranged in the column gold box, but the second lines outside in the line gold box. With a larger diameter of the low-pressure column, however, the supercooling counterflow and the second lines are advantageously outsourced to the separate line cold box.

If there is talk before and below of the fact that the vertically running sections of the second lines are accommodated “at least in part” in their respective cold boxes, this can in particular be a predominant part of corresponding sections, in particular at least 50%, at least 60 %, at least 80%, at least 90% or at least 95% of the respective length. As already mentioned, other apparatuses are also accommodated in the corresponding cold box, in particular in the separate line cold box. This is particularly an instrumentation for flow, temperature and pressure measurement. Appropriate devices are prefabricated as far as possible, i.e. The measuring lines are laid from the respective cryogenic pipelines through the sheet metal jacket of the cold box. Optionally, these are already connected to transmitters installed on the box

As already mentioned, the present invention makes it possible, in particular, to dispense with a two-part design of a crude argon column or a modified crude argon column. This is ensured in particular by the fact that different packing densities are used in the top section of the low-pressure column and the crude argon column. It is particularly advantageous here if a first packing area with a first packing density is formed in a lower area of the foot section of the low pressure column and a second packing area is designed in the argon recovery column with a second packing density, the first packing density being in particular less than 1000 square meters per cubic meter and the second packing density more than 750 Square meters per cubic meter. The second packing density is at least 250 square meters per cubic meter larger than the first packing density. In other words, the crude argon column is packed more densely than the lower region of the foot section of the low-pressure column, and the crude argon column can therefore, as explained above, be formed with a lower height.

Advantageously, a transfer pump or a plurality of transfer pumps arranged in parallel and / or provided redundantly can be provided for fluid transfer between a lower area of the head section of the low-pressure column and an upper area of the foot section of the low-pressure column. For example, three transfer pumps each delivering 50% of the required pump output can be provided.

The present invention further relates to a method for the low-temperature separation of air, which is characterized in that an air separation system is used, as has been explained above in various configurations. This process feeds into the high pressure column. A bottom liquid with an oxygen content of 30 to 50 mole percent is formed in the high-pressure column and at least partially transferred to the foot section of the low-pressure column. A top gas is formed in the foot section of the low pressure column and at least partially transferred into the argon recovery column and / or into the top section of the low pressure column. A bottom liquid is formed in the argon recovery column and at least partially transferred to the top section of the low-pressure column. A bottom liquid is formed in the top section of the low-pressure column and transferred to a lower region of the crude argon column and / or to an upper region of the foot section of the low-pressure column.

A method according to the invention also proposed for creating an air separation plant, as explained above in embodiments, comprises four separation units in the form of a high-pressure column, a foot section of a two-part low-pressure column, a head section of the two-part low-pressure column and a one-part argon recovery column, and the four separation units at least in part are connected to one another and / or to one or more further apparatuses by means of lines, the lines one or more first lines and several second ones Include lines, wherein the one or more first lines is or are one or more lines that open into a head region of the foot portion of the low pressure column and / or a line that opens into a gas space of a top condenser of the argon recovery column. According to the invention, it is provided that vertically running sections of the second lines are at least partially accommodated in a cold box, which is designed as a column cold box, in which the head section of the low-pressure column is arranged, or as a separate line cold box, in which none of the four separation units is arranged. As mentioned, the first lines can also be arranged accordingly.

The prefabrication of the within the scope of the present invention includes, in particular, prefabricating one or more column cold boxes with the respective separation units and / or the line cold box at a first geographical position, transporting them to a second geographical position, and using the air separation plant at the second geographical position to create the cold boxes. Any pre-fabricated cold boxes can be created in this way.

The present invention is explained in more detail below with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention.

Brief description of the drawings

• Figure 1 illustrates an air separation plant according to an embodiment of the present invention in a schematic partial representation.
• Figure 2 illustrates an air separation plant according to an embodiment of the present invention in a schematic partial representation.
• Figure 3 illustrates an air separation plant according to an embodiment of the present invention in a schematic partial representation.
• Figure 3 illustrates an air separation plant according to an embodiment of the present invention in a schematic partial representation.
• Figure 5 illustrates arrangements of cold boxes in air separation plants according to another embodiment of the present invention.
• Figure 6 illustrates arrangements of cold boxes in air separation plants according to another embodiment of the present invention.
• Figure 7 illustrates arrangements of cold boxes in air separation plants according to another embodiment of the present invention.

Detailed description of the drawings

Figure 1 shows an air separation plant, which is set up for operation according to an embodiment of the present invention, in a greatly simplified partial representation. The air separation plant includes other components and is shown here in a highly simplified form as 100.

The air separation plant 100 has a high-pressure column 1, a two-part low-pressure column with a foot section 2 and a head section 3, a one-piece raw argon column 4 and a pure argon column 5. The high-pressure column 1, the foot section 2 of the low-pressure column, the head section 3 of the low-pressure column, the crude argon column 4 and the pure argon column 5 each represent "separation units" in the parlance used here and are at least partially connected to one another by means of lines, which are summarized here with 6 connected to other apparatuses such as a supercooling counterflow 7 and a main heat exchanger, not shown here.

With regard to the functioning of the illustrated components of the air separation plant 100, which is well known from the prior art, reference is expressly made to the specialist literature cited at the beginning. In the air separation plant 100 illustrated here, air is fed into the high-pressure column 1 in the form of a material stream A. The air can in particular be compressed by means of a main air compressor (not shown) and optionally one or more secondary compressors or boosters (also not shown) and purified, for example by adsorption, and cooled in the main heat exchanger (not shown). The use of several compressed, purified and cooled air streams is also known. This can also be partially fed into the foot and / or head section 2, 3 of the low pressure column and, if necessary, relaxed to an appropriate pressure level or provided at different pressure levels.

In the air separation plant 100 shown here, a bottom liquid with an oxygen content of 30 to 50 mole percent is formed in the high-pressure column 1 and at least partially transferred in the form of a stream B into the top section 3 of the low-pressure column. The stream B or partial streams thereof can be used for cooling top condensers 4a and 5a of the raw and pure argon columns 4, 5. Alternatively, any other medium that is drawn off between the sump and the top of the high-pressure column 1 can also be used.

A top gas is formed in the foot section 2 of the low-pressure column and transferred partly in the form of a material flow C into the crude argon column 4 and partly in the form of a material flow D into the head section 3 of the low-pressure column. A sump liquid is formed in the crude argon column 4 and at least partially transferred in the form of a stream E into the foot section 2 of the low-pressure column. A bottom liquid is formed in the head section 3 of the low-pressure column, which is transferred here in the form of a material flow F into a lower region of the crude argon column 4. This bottom liquid can then be transferred as part of the already mentioned stream E into the foot section 2 of the low pressure column. Alternatively, it is also possible to transfer the material flow F directly into an upper region of the foot section 2 of the low pressure column.

In the air separation plant 100 shown here, the high-pressure column 1 and the foot section 2 of the low-pressure column are arranged in a column-type cool box 10, the head section 3 of the low-pressure column in a further column-type cool box 20 and the crude argon column 4 in a further column-type cool box 30. A separate line gold box 40 is provided primarily for receiving the lines 6. The lines 6 can be subdivided into lines which are at least partially accommodated with vertical sections in the line gold box (“second lines”) and those that are optionally arranged therein (“first lines”). The first lines include those which open into the head region of the foot section 2 of the low-pressure column, that is to say carry the material flows C or D and E, and a line which carries gas from an evaporation space of the top condenser 4a Crude argon column 4 (and possibly from an evaporation chamber of the top condenser 5a of the pure argon column 5) is transported into the top section 3 of the low-pressure column, as illustrated here in the form of a material flow K. The other lines belong to the "second lines".

The pure argon column 5 is arranged here together with the raw argon column 4 in the common column cool box 30. A supercooling counterflow 7 is arranged in the air separation plant 100 together with at least part of the vertical sections of the second lines in the separate piping cold box 40.

Liquid air S can be fed into the high-pressure column 1. Gaseous pressurized nitrogen T from the high pressure column 1, gaseous low pressure nitrogen U from the head section 3 of the low pressure column, internally compressed gaseous pressurized oxygen V, so-called impure nitrogen W, liquid nitrogen X, liquid oxygen Y and liquid argon Z can be provided as products. The gaseous media are warmed in particular in the main heat exchanger of the air separation plant. Gas can be withdrawn from the pure argon column 5 and released into the atmosphere.

Figure 2 shows an air separation plant, which is set up for operation according to a further embodiment of the present invention, in a greatly simplified partial illustration. This air separation plant also includes other components. It is given here in a highly simplified form with 200. The components of the air separation plant 200, which are identified here with identical reference numerals as in FIG Figure 1 are also illustrated in the specialist literature and in the explanations Figure 1 directed. Only the differences are explained below.

The air separation unit 200 differs from the air separation unit 100 essentially in that at least some of the vertical sections of the second lines are arranged in a line cold box 20a, in which the head section 3 of the low-pressure column is also arranged. In the example shown, the line cold box 20a also contains the supercooling counterflow 7. In contrast to the illustration in FIG Figure 2 the supercooling counterflow 7 can be arranged in particular below the head section 3 of the low pressure column. This is in particular due to the lower height of the head section 3 of the low pressure column in comparison for the most part of the further separation units in the air separation plant 200 possible, in particular if a lower packing density is used in the head section 3.

Figure 3 shows an air separation plant, which is set up for operation according to a further embodiment of the present invention, in a greatly simplified partial illustration. This air separation plant also includes other components. It is given here in a highly simplified form with 300. The components of the air separation plant 300, which here have identical reference numerals as in FIG Figure 1 and 2 are also illustrated in the specialist literature and in the explanations Figure 1 and 2 directed. Only the differences are explained below.

The air separation plant 300 differs from the air separation plants 100 and 200 essentially in that here the raw argon column 4 is arranged alone in a column cold box 30a, and in that the pure argon column 5 is arranged here in a line cold box 40a provided primarily for receiving the explained sections of the second lines , In the example shown, the line cold box 40a also contains the supercooling counterflow 7. In contrast to the illustration in FIG Figure 3 the supercooling counterflow 7 can be arranged in particular below the pure argon column 5. This is possible in particular due to the lower height of the pure argon column compared to the predominant part of the other separation units of the air separation plant 300.

As illustrated in the form of the linkage P, the material stream D 'is first led into the head section 3 of the low pressure column and a part in the form of the material stream C' is removed from it and fed into the crude argon column 4.

Figure 4 shows an air separation plant, which is set up for operation according to a further embodiment of the present invention, in a greatly simplified partial illustration. This air separation plant also includes other components. It is given here in a highly simplified form at 310. In contrast to the air separation plant 300, no combination of raw and pure argon column is provided here. Rather, a modified crude argon column 4, which has been explained several times, is provided, from which a pure argon stream L is already removed. Therefore, no pure argon column 5 is arranged here in the line gold box 4a.

Figure 5 illustrates in views 5a to 5d arrangements of cold boxes in an air separation plant according to an embodiment of the present invention. The air separation plant can in particular according to the air separation plant 100 Figure 1 A corresponding arrangement can, however, also take place in air separation plants other than air separation plant 100, in particular in an air separation plant in which only one argon recovery column is used instead of a combination of crude argon column 4 and pure argon column 5. In Figure 5 Top views of cold boxes 10 to 40 without the respective separating units are illustrated, with another cold box containing a main heat exchanger (indicated by 8 in view 5a and omitted in the other views for the sake of clarity) is designated by 90. The cold box 90 was also referred to above as the "main heat exchanger cold box".

First to fourth side surfaces of the fourth cold box 40 are indicated by 41 to 44. A first column gold box 10 (with the high pressure column 1 and the foot section 2 of the low pressure column), a line gold box 40 and the main heat exchanger gold box 90, which contains the main heat exchanger 8 of the air separation unit 100, are arranged in all views 5a to 5d in such a way that the first side surface 41 closes the main heat exchanger cold box 90 and the second side surface 43 faces the column cold box 10. A second column gold box 20 (with the head section 3 of the low pressure column) and a third column gold box 30 (with the argon recovery column) can be arranged differently, in such a way that the third side surface 43 faces the second column gold box 20 and the fourth side surface 44 faces the third column gold box 30 points, as illustrated in view 5a, or that the third side surface 43 faces the third pillar gold box 30 and the fourth side face 44 faces the second pillar gold box 20, as illustrated in view 5b, or that the third side surface 43 faces the second pillar gold box 20 and the third pillar gold box 30 faces as illustrated in view 5c, or that the fourth side surface 44 faces the second pillar gold box 20 and the third pillar gold box 30 as illustrated in view 5d.

Figure 6 illustrates arrangements of cold boxes in air separation plants according to further embodiments of the present invention. The air separation plants are designated with 400 to 700 and are also illustrated in a simplified top view with the omission of further essential components.

In the air separation plant 400, all of the separation units, namely the high-pressure column 1, the foot section 2 of the low-pressure column, the head section 3 of the low-pressure column and the crude argon column 4 with the pure argon column 5 are arranged in a common column cool box, which is indicated here at 50. Furthermore, the separate line gold box 40 is provided here. In the air separation plants 500 and 600, on the other hand, the high-pressure column 1 and the foot section 2 of the low-pressure column are arranged together with a further separation unit in a common column gold box 60, 70, the remaining separation unit is arranged in a further column gold box 20, 30. In the air separation plant 700 and 600, on the other hand, only the high-pressure column 1 and the foot section 2 of the low-pressure column are arranged together in a common column gold box 10, the remaining separation units are arranged together in a further column gold box 80. The line gold box 40 is also provided here in each case. For the respective elements, which are provided here with identical reference numerals as before, reference is expressly made to the above statements.

Figure 7 illustrates arrangements of cold boxes in air separation plants according to further embodiments of the present invention. The air separation plants are also illustrated here in a simplified top view, leaving out other essential components. A line gold box 40 is provided in each case Figure 7 The arrangement shown on the left shows all of the separating units, namely the high-pressure column 1, the foot section 2 of the low-pressure column, the head section 3 of the low-pressure column and the crude argon column 4 with the pure argon column 5 in a common column cool box, which is also indicated here by 50, to which are arranged immediately connects the cable gold box 40. The pillar gold box and the line gold box 40 can in particular be connected to one another at their corresponding surfaces. In the in Figure 7 The view shown on the right is of a corresponding L-shaped pillar gold box, denoted here by 50 ', and the line gold box 40 is fitted into the pillar gold box 50' in the manner shown.

Claims (15)

Air separation plant (100-700) with four separation units (1 -4) in the form of a high-pressure column (1), a foot section (2) of a two-part low-pressure column, a head section (3) of the two-part low-pressure column and a one-part argon extraction column (4), wherein the four separation units (1-4) are connected at least in part by means of lines (6) to one another and / or to one or more further apparatuses (7, 8), the lines (6) being one or more first lines and several second ones Comprising lines, the one or more first lines comprising one or more lines which open into a head region of the foot section (2) of the low pressure column and / or a line which opens into a gas space of a top condenser (5a) of the argon recovery column (4) , is, or are, characterized in that vertically running sections of the second lines are at least partially accommodated in a cold box (20a, 40, 40a) t, which is designed as a column cold box (20a) in which the head section (3) of the low-pressure column is arranged, or as a separate line cold box (40, 40a) in which none of the four separation units (1-4) is arranged. Air separation plant (100-700) according to Claim 1, in which one or more vertically extending sections of the first line or the first plurality of lines are also or are at least partially accommodated in the cold box (20a, 40, 40a) in which the vertically extending lines Sections of the second lines are at least partially housed. Air separation plant (100-700) according to claim 1 or 2, in which the separate line cold box (40, 40a) is provided, and in which - A common Säulencoldbox (50) is provided, in which all of the four separation units (1-4) are accommodated, or - A common Säulencoldbox (60-80) is provided, in which the high pressure column (1), the foot section (2) of the low pressure column and exactly one more of the four separation units (1-4) are received, one a further column cool box (30) is provided, in which the remaining of the four separation units (1-4) is accommodated, or - A common pillar gold box (10) is provided, in which the high pressure column (1) and the foot section (2) of the low pressure pillar are accommodated, wherein a further common pillar gold box (80) is provided in which the two remaining four separation units (1-4 ) are included, or - A common column gold box (10) is provided, in which the high pressure column (1) and the foot section (2) of the low pressure column are accommodated, two further column gold boxes (20, 30) being provided, in each of which one of the two remaining four separation units ( 1-4) are included. An air separation plant (100-700) according to claim 3, wherein a raw argon column as the argon recovery column and a pure argon column (5) are provided as a fifth separation unit, the pure argon column (5) in the line gold box (40a) or in that of the column gold boxes (50, 60, 80) is accommodated in the crude argon column (4). Air separation plant (100-700) according to Claim 3, in which a separation unit which is set up for the enrichment or extraction of a krypton / xenon or helium / neon mixture is provided as a fifth separation unit (5), this fifth separation unit (5) being in the line cold box (40a) or in the one of the column cool boxes (50, 60, 80), in which the argon recovery column (4) is received. Air separation plant (100-700) according to one of Claims 3 to 5, in which a separate main heat exchanger gold box (90) is provided, in which the main heat exchanger (8) of the air separation plant (100) is accommodated, one of the side faces (41) of the line cold box ( 40) is arranged parallel to a side face of the main heat exchanger cool box (90). Air separation plant (100-700) according to Claim 6, in which at least one further of the side surfaces (42-43) of the line gold box (40) in each case assigns a side surface to one of the column gold boxes (10-80). Air separation plant (100-700) according to one of the preceding claims, in which the separate line cold box (40, 40a) is provided and in which it has a size of less than 6 meters in an extension direction. Air separation plant (100-700) according to one of the preceding claims, in which the separate line cold box (40, 40a) is provided and in which a supercooling counterflow (7) is arranged in the line gold box (40, 40a). Air separation plant (100-700) according to one of the preceding claims, in which the separate line cold box (40, 40a) is provided and in which it extends in a first direction parallel to the vertically extending sections of the second lines by at least a factor of 5 greater than in the directions vertical to this. Air separation plant (100-700) according to one of the preceding claims, in which the head section (3) of the low-pressure column has a smaller cross section than the foot section (2) of the low-pressure column. Air separation plant (100-700) according to one of the preceding claims, in which one for transferring fluid between a lower region of the head section (3) of the low-pressure column and an upper region of the foot section (2) of the low-pressure column provides a transfer pump or a plurality of parallel and / or redundant arrangements Transfer pumps are provided. Air separation plant (100-700) according to one of the preceding claims, in which a first packing area with a first packing density is formed in a lower area of the foot section (2) of the low-pressure column and in which a second packing area with a second packing density in the argon recovery column (4) the first packing density is less than 1,000 square meters per cubic meter and the second packing density is more than 750 Square meters per cubic meter and the second packing density is more than 250 square meters per cubic meter greater than the first packing density. Method for the low-temperature separation of air, characterized in that an air separation plant (100-700) according to one of the preceding claims is used, air being fed into the high-pressure column (1) and a sump liquid with an oxygen content of 30 to 50 mole percent is formed and at least partially transferred to the top section (3) of the low pressure column, a top gas is formed in the bottom section (2) of the low pressure column and at least partially transferred to the argon recovery column (4) and / or into the top section (3) of the low pressure column , and a sump liquid is formed in the argon recovery column (4) and at least partially transferred into the top section (2) of the low pressure column. Method for creating an air separation plant (100-700) according to one of claims 1 to 13, in which four separation units (1-4) in the form of a high-pressure column (1), a foot section (2) of a two-part low-pressure column, the head section (3) the two-part low-pressure column and a one-part argon recovery column (4) are provided, and the four separation units (1-4) are at least partly connected to one another and / or to one or more further apparatuses (7, 8) by means of lines (6), wherein the lines (6) comprise one or more first lines and a plurality of second lines, the one or more first lines one or more lines which open into a head region of the foot section (2) of the low pressure column and / or a line which opens or is in a gas space of a top condenser (5a) of the argon recovery column (4), characterized in that vertically extending sections d he second lines are at least partially accommodated in a cold box (20a, 40, 40a), which is used as a column gold box (20a) in which the head section of the low-pressure column is arranged, or as a separate line gold box (40, 40a) in which none of the four Separating units (1-4) is arranged, is formed.

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