EP3696486A1 - Method and apparatus for providing one or more gaseous oxygen rich air products - Google Patents

Abstract

A method for producing one or more oxygen-rich, gaseous air products is proposed, in which in an air separation plant (100-300) a first process stream, which comprises predominantly or exclusively pressurized non-liquefied air, and a second process stream, which predominantly or exclusively pressurized liquefied air comprises, are formed, and in which the first and the second process stream are separately subjected to expansion to an operating pressure level of a high pressure column (111) of the air separation plant (100-300) and partially or completely fed into the high pressure column (111). It is provided that air is used to form the first and the second process stream, which is provided as part of a total amount of air at a first pressure level and a first temperature level, the total amount of air using an air compressor (101) and a booster (102), which is arranged parallel to the air compressor (101), is brought to the first pressure level, the booster (102) being coupled to an expansion turbine (109) used in the expansion of a third process stream and being driven by this. An air separation plant (100-300) is also the subject of the present invention.

Description

The invention relates to a method for providing one or more oxygen-rich, gaseous air products and a corresponding system according to the preambles of the independent claims.

State of the art

The production of air products in the liquid or gaseous state by the low-temperature decomposition 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.

As used herein, the term "air product" is intended to refer to a fluid that is provided, at least in part, by the cryogenic decomposition of atmospheric air. An air product has one or more air gases contained in atmospheric air in a different composition than in atmospheric air. An air product can basically be in a gaseous, liquid or supercritical state and can be transferred from one of these states to another. In particular, a liquid air product can be converted into the gaseous state ("evaporated") or converted into the supercritical state ("pseudo-evaporated") by heating to a certain pressure, depending on whether the pressure during the heating is below or above the critical pressure .

Air separation plants have rectification column systems which are conventionally designed as two-column systems, in particular as classic Linde double-column systems, but can also be designed as three- or multi-column systems. In addition to the rectification columns for obtaining nitrogen and / or oxygen in liquid and / or gaseous state, i.e. the rectification columns for nitrogen-oxygen separation, rectification columns can be provided for obtaining further air components, in particular the noble gases krypton, xenon and / or argon. Often the The terms “rectification” and “distillation” and “column” and “column” or terms composed thereof are used synonymously.

The rectification columns of the rectification column systems mentioned are operated at different pressures. Known double column systems have what is known as a 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 of 4 to 7 bar, in particular approx. 5.3 bar. The low-pressure column is operated at a pressure of typically 1 to 2 bar, in particular about 1.4 bar. In certain cases, higher pressures can also be used in both rectification columns. The pressures given here are absolute pressures at the top of the columns given.

For air separation, so-called main (air) compressors / booster (Main Air Compressor / Booster Air Compressor, MAC-BAC) processes or so-called high air pressure (HAP) processes can be used. The main compressor / booster processes are the more conventional processes, while high-air pressure processes have been used more and more recently as alternatives. The present invention is suitable for both variants of air separation, but can be used in particular in connection with HAP processes. Due to the significantly lower costs - main and booster compressors are integrated in one machine, so to speak - and comparable efficiency, high-air pressure processes can represent an advantageous alternative to the main compressor / booster processes.

Main compressor / booster processes are characterized in that only part of the total amount of feed air supplied to the rectification column system is compressed to a pressure which is significantly above, ie by at least 3, 4, 5, 6, 7, 8, 9 or 10 bar the pressure at which the high pressure column is operated. A further part of the feed air quantity is only compressed to this pressure or a pressure which differs therefrom by no more than 1 to 2 bar, and at this point it is fed into the high pressure column. A main compressor / booster method is, for example, at Häring (see above) in Figure 2 .3A shown.

In the case of a high-air pressure process, on the other hand, the entire amount of feed air supplied to the rectification column system is compressed to a pressure which is substantially, ie by at least 3, 4, 5, 6, 7, 8, 9 or 10 bar, and for example up to 14, 16, 18 or 20 bar, too above the pressure at which the high pressure column is operated. High air pressure methods are, for example, from the EP 2 980 514 A1 and the EP 2 963 367 A1 known.

High air pressure processes are typically used with what is known as internal compression (IV, IC). During the internal compression, at least one gaseous, pressurized air product, which is provided by means of the air separation plant, is formed in that a cryogenic, liquid air product is removed from the rectification column system, subjected to a pressure increase to a product pressure, and the product pressure by heating into the gaseous or supercritical state is convicted. For example, gaseous, pressurized oxygen (GOX IV, GOX IC), gaseous, pressurized nitrogen (GAN IV, GAN IC) and / or gaseous, pressurized argon (GAR IV, GAR IC) can be generated by means of internal compression. The internal compression offers a number of advantages compared to an alternatively also possible external compression and is explained, for example, by Häring (see above) in Section 2.2.5.2, "Internal Compression". Systems for the low-temperature separation of air, in which internal compression is used, are also in the US 2007/0209389 A1 and in the WO 2015/127648 A1 shown.

The object of the present invention is to provide a cost-effective and efficient high-air pressure method, the aim being to use it advantageously under certain boundary conditions specified below.

Disclosure of the invention

Against this background, the present invention proposes a method for providing one or more oxygen-rich, gaseous air products and a corresponding system with the respective features of the independent patent claims. Refinements of the invention are the subject matter of the respective dependent claims and the following description.

Further principles of the invention are first explained in more detail and terms used to describe the invention are defined.

An “amount of feed air” or “feed air” for short is understood here to mean all of the air supplied (“used”) to the rectification column system of an air separation plant. As already explained above, this feed air quantity is only partially compressed in a main compressor / booster process to a pressure level which is significantly above the pressure level of the high pressure column. In contrast, in a high-air pressure process, the entire amount of input air is compressed to such a high pressure level. For the meaning of the term “clearly” in connection with main compressor / booster and high-air pressure processes, reference is made to the explanations above.

A "cryogenic" liquid is understood here to mean a liquid medium whose boiling point is well below the ambient temperature, e.g. at -50 ° C or less, especially -100 ° C or less. Examples of cryogenic liquids are liquid air, liquid oxygen, liquid nitrogen, liquid argon or liquids that are rich in the compounds mentioned.

Regarding the devices and apparatus used in air separation plants, reference is made to specialist literature such as Häring (see above), in particular Section 2.2.5.6, "Apparatus". In the following, some aspects of corresponding devices are explained in more detail for clarification and clearer delimitation.

In air separation plants, multi-stage turbo compressors, which are referred to here as "main air compressors", are used to compress the amount of air used. The mechanical structure of turbo compressors is basically known to the person skilled in the art. In a turbo compressor, the medium to be compressed is compressed by means of turbine blades which are arranged on a turbine wheel or directly on a shaft. A turbo compressor forms a structural unit which, however, in a multi-stage turbo compressor can have several compressor stages. A compressor stage usually comprises a turbine wheel or a corresponding arrangement of turbine blades. All of these compressor stages can be driven by a common shaft. However, it can also be provided that To drive compressor stages in groups with different shafts, whereby the shafts can also be connected to one another via gears.

The main air compressor is also characterized in that it compresses the entire amount of air fed into the distillation column system and used to produce air products, that is to say the entire amount of air used. Correspondingly, a "post-compressor" can also be provided, in which, however, only part of the feed air quantity compressed in the main air compressor is brought to an even higher pressure. This can also be designed as a turbo compressor. For the compression of partial amounts of air, further turbo compressors are typically provided, which are also referred to as boosters, but only perform compression to a relatively small extent in comparison to the main air compressor or the booster. A booster can also be present in a high-air pressure process, but this then compresses a portion of the amount of input air starting from a higher pressure level.

Furthermore, air can be expanded at several points in air separation plants, for which purpose, among other things, expansion machines in the form of turbo expanders, also referred to here as "expansion turbines", can be used. Turbo expanders can also be coupled with turbo compressors and drive them. Are one or more turbo compressors without externally supplied energy, i. Driven only by one or more turbo expanders, the term "turbine booster" is also used for such an arrangement. In a turbine booster, the turboexpander (the expansion turbine) and the turbo compressor (the booster) are mechanically coupled, with the coupling being able to take place at the same speed (for example via a common shaft) or at different speeds (for example via an interposed gearbox).

A “cold compressor” or “cold booster” is to be understood here as meaning a compressor or booster, the fluid at a temperature level below the ambient temperature, in particular at less than 0 ° C, -50 ° C or -100 ° C and possibly more than -150 ° C or -200 ° C.

Liquid, gaseous or even fluids present in the supercritical state can, in the language used here, be rich or poor in one or more Components, where "rich" for a content of at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% and "poor" for a content of at most 25%, May represent 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" just made, but in particular denotes a content of more than 90%. If, for example, "nitrogen" is mentioned here, it can be a pure gas, but also a gas rich in nitrogen.

The terms “pressure level” and “temperature level” are used below to characterize pressures and temperatures, which is intended to express that pressures and temperatures do not have to be used in the form of exact pressure or temperature values in order to implement an inventive concept. However, such pressures and temperatures typically move in certain ranges, for example ± 1%, 5% or 10% around a mean value. Different pressure levels and temperature levels can be in disjoint areas or in areas that overlap. In particular, pressure levels include, for example, unavoidable or expected pressure losses, for example due to cooling effects. The same applies to temperature levels. The pressure levels given here in bar are absolute pressures.

Advantages of the invention

Known high-air pressure processes are often classified and differentiated according to the so-called liquid performance or according to the ratio of internally compressed products to liquid products. The liquid output denotes the amount of air products that are carried out in liquid form from the system or a corresponding process, which means that no evaporation or pseudo-evaporation takes place. By means of such products, no feed streams into the plant or the process can be cooled. Therefore, if fewer air products are carried out in liquid form from the system or a corresponding process, but rather they are vaporized or pseudo-vaporized, there is, so to speak, excess cold.

In the case of a low liquid output, a so-called cold booster can therefore be used, for example, to increase the process efficiency by converting such excess cold into higher air pressure: The heat input through the cold booster partially destroys the excess cold; In return, however, the cold booster compresses part of the feed air so that, for example, the performance of the main air compressor can be reduced accordingly. As already mentioned above, the intake temperature of a cold booster is below the ambient temperature, so that the power consumption is reduced with an ideal gas behavior assumed for the sake of simplicity.

The invention is now intended to be particularly suitable for a high-air pressure process in which gaseous oxygen is to be produced without (significant) liquid production. The specialty is the division of the gaseous oxygen into two fractions of different pressures (almost unpressurized and pressurized, for example at approx. 31 bar) in a ratio of approx. 1 to 2. An exemplary product range of air products (all gaseous) for which The invention is intended to be suitable is shown in Table 1 below. However, the invention is not limited to this specific example or even only to the orders of magnitude given here. <b> Table 1 </b> product Amount (Nm ³ / h) Pressure (bar) oxygen 18,700 1.3 oxygen 44,750 31 argon 1,865 17th nitrogen 75,000 1.3

The method proposed according to the invention should also be particularly suitable for the use of feed air which is provided at a pressure level of approx. 6 bar (for example from an existing supply network at the site, a so-called "air rail"). For this reason, an air separation plant as proposed according to an embodiment of the invention, or a corresponding method, comprises an interconnection as is customary in a main compressor / booster method, in which an injection turbine (Lachmann turbine) is also provided. As explained below, however, in the context of the present invention, instead of an injection or Lachmann turbine, a second turbine can also be used, which expands air into the high-pressure column in the manner of a Claude turbine. The terms "Claude-Turbine" and "Lachmann-Turbine" refer to specialist literature, for example FG Kerry, Industrial Gas Handbook: Gas Separation and Purification, CRC Press, 2006 , in particular Sections 2.4, "Contemporary Liquefaction Cycles", 2.6, "Theoretical Analysis of the Claude Cycle" and 3.8.1, "The Lachmann Principle".

Overall, against this background, the present invention proposes a method for the production of one or more oxygen-rich, gaseous air products, in which in an air separation plant a first process stream, which comprises predominantly or exclusively pressurized non-liquefied air, and a second process stream, which predominantly or exclusively liquefies pressurized air Comprises air, are formed, and in which the first and the second process stream are separately subjected to an expansion to an operating pressure level of a high pressure column of the air separation plant and are partially or completely fed into the high pressure column. In this context it is understood that, after the expansion, further material flows can be fed to the first and the second process flow and can be fed into the high-pressure column together with these. Furthermore, it goes without saying that the entire first or second process stream does not have to be fed into the high-pressure column after the expansion.

The first process stream, which predominantly or exclusively comprises pressurized, non-liquefied air, is expanded in particular in an expansion turbine, as will also be explained in detail below. It is a so-called turbine flow, as it is also formed in known methods of air separation. The expansion turbine used to expand a corresponding turbine flow is a typical Claude turbine. The second process flow, which is formed within the scope of the present invention and comprises predominantly or exclusively pressurized liquefied air, corresponds to a known throttle flow, as it is also formed in the prior art. In the context of the present invention, for example, an expansion valve can be used to relax the second process flow, that is to say the throttle flow; however, it can also, for example, be a so-called liquid turbine or a So-called sealing fluid expander (Dense Liquid Expander, DLE), as it is known from the prior art, are used. Advantages of liquid turbines are extensively described in the prior art, for example in Häring (see above), Section 2.2.5.6, "Apparatus", pages 48 and 49.

It goes without saying that the first and the second process stream are formed within the scope of the present invention at a pressure level which is above the operating pressure level of the high pressure column. In the context of the present invention, the operating pressure level of the high pressure column is understood to mean, in particular, a pressure level as is present at a feed point of the first or second process stream into the high pressure column, or a pressure range which includes the pressures at these feed points. It is known that rectification columns can have pressure gradients during operation. Therefore, as mentioned, the term “operating pressure level” denotes the pressure at the respective feed point or a corresponding pressure range.

According to the invention, it is provided that air is used to form the first and the second process flow, which is provided as part of a total amount of air at a first pressure level and a first temperature level, the total amount of air using an air compressor and a booster, which runs parallel to the air compressor is arranged, is brought to the first pressure level, and wherein the booster is coupled to an expansion turbine used in the expansion of a third process stream and is driven by this. The third process stream is also formed using part of the total amount of air, as explained in detail below.

The air that is used to form the first and the second process stream is, in the context of a particularly preferred embodiment of the present invention, which will now be explained in advance, a cooling to a second temperature level, a compression to a second pressure level, a cooling to a third temperature level and, while maintaining a liquid phase and a gas phase, is subjected to a phase separation. In the context of the present invention, the first temperature level is in particular above 0 ° C., for example at ambient temperature, typically in a range from 10 to 50 ° C. The second temperature level is in the context of the present invention especially at -120 to -150 ° C; the compression to the second pressure level therefore takes place starting from a correspondingly low temperature level. A compressor or booster used for the compression to the second pressure level, which is advantageously driven by means of an expansion turbine, which expands the first process stream to the operating pressure level of the high pressure column, is therefore a so-called cold booster, as already explained in the introduction.

The first pressure level (upstream of the cold booster) is within the scope of the embodiment of the present invention just mentioned, in particular 7 to 13 bar, the second pressure level (downstream of the cold booster) to which the air used to form the first and second process streams after cooling is compressed to the second temperature level, in particular at 11 to 17 bar. The third temperature level, to which the air used to form the first and the second process stream is cooled in this embodiment after compression to the second pressure level (after it has previously warmed up through compression) is in particular -140 to -170 ° C .

In the context of the just mentioned embodiment of the present invention, it is provided that the first process stream is formed using at least part of the gas phase from the phase separation mentioned, and that the second process stream is formed using at least part of the liquid phase that is formed in the phase separation becomes. In particular, the first process stream can comprise the entire gas phase and / or the second process stream can comprise the entire liquid phase, which are each formed in the phase separation.

In this embodiment of the invention, the first process stream is supplied to the expansion to the pressure level of the high pressure column at the second pressure level and the third temperature level, and the second pressure level and the third temperature level are selected in the context of the present invention in particular such that the expansion of the first process stream to the operating pressure level of the high pressure column forms a liquid fraction of 5% to 15%, based on the entire first process stream. For example, the liquid content in the context of the present invention is approx. 10%.

In other words, the expansion turbine used for the expansion of the first process stream is operated in the context of the mentioned embodiment of the present invention with a defined (dew) state at the turbine inlet, which leads to a corresponding liquid content at the turbine outlet. Corresponding operation allows the process potential to be optimally exploited and reliable operation results. The mentioned liquid portion in particular denotes a portion that is calculated from the respective standard volumes of the portions formed.

The operation of the expansion turbine for expansion of the first process flow is to be considered in particular in connection with an injection turbine used or an expansion turbine which relaxes a further turbine flow, as explained below.

If one were to look at the proposed method conventionally, i.e. with the usual optimization of the turbine inlet temperatures, one would find that the outlet state with a corresponding injection turbine goes heavily into pre-liquefaction, and the inlet state of the turbine used to expand the first process flow is only relatively low Has overheating of approx. 2 to 2.5 K compared to the dew point. Such operating states are unfavorable from the point of view of operating technology, since on the one hand additional measures would be required to safely convey the liquid occurring at the outlet of the injection turbine into the low-pressure column and, on the other hand, there is a pre-liquefaction upstream of the expansion turbine used to expand the first process stream could. With such a pre-liquefaction, damage to the inlet nozzles in a corresponding expansion turbine and the impeller surface may be feared.

Therefore, within the scope of the mentioned embodiment of the present invention, it is also proposed to set the entry state of a corresponding process flow into the injection turbine higher or to select it in such a way that no liquid occurs at its exit. The state of entry into the turbine used to relax the first process flow is set lower in return, so that the "missing" liquid from the blow-in turbine is practically formed when the first process flow is relaxed.

An essential feature of the embodiment of the present invention explained above is that the turbine flow, i.e. the first process stream and the second process stream, that is to say a throttle stream, are cooled together and pre-liquefied before entering the turbine, as explained above. The resulting liquid is separated in a separator and in the form of the second process stream, in particular, is fed back into the heat exchanger for the purpose of subcooling. The gas from a corresponding separator is fed directly into the turbine in the form of the first process stream, as already described above in other words.

Merely for the sake of clarity, it should be mentioned again in summary that the air used to provide the first and the second process stream is cooled to the second temperature level at the first pressure level and the first temperature level, the compression to the second pressure level at the second temperature level and the first pressure level, the cooling to the third temperature level at the second pressure level and a temperature level below the second temperature level, and the phase separation is supplied to the second pressure level and the third temperature level.

In all cases, in addition to the second process stream, a further process stream can also be liquefied in a main heat exchanger of the air separation plant and partially or completely expanded in the high-pressure column, in particular together with the second process stream, with expansion being separate from the second process stream or can be done together with this.

As already explained, an injection turbine is advantageously used within the scope of the present invention or a corresponding material flow is formed. However, a second turbine flow can also be provided. Using a corresponding process flow, as mentioned, a booster, which is used to provide the total amount of air at the first pressure level, is driven. In other words, the present invention comprises that a third process stream, which comprises predominantly or exclusively pressurized, non-liquefied air, is formed, the third process stream being expanded upon Operating pressure level of a low pressure column of the air separation plant and can be partially or fully fed into the low pressure column, or subjected to an expansion to the operating pressure level of the high pressure column of the air separation plant and can be partially or completely fed into the high pressure column. The third process stream is fed to the expansion, in particular at a temperature level that is more than 10 K above the third temperature level and differs by less than 10 K from the second temperature level.

As already mentioned, the expansion of such a third process stream is carried out in the context of the present invention in particular in such a way that no or no significant portion of liquid is formed at the outlet of an expansion turbine used for this expansion. This liquid portion, which is necessary for balance reasons, is instead, as already mentioned above, formed in the context of the present invention in particular in the expansion turbine used for expanding the first process flow.

In the context of the present invention, air is also used to form the third process flow, which air is provided as part of the total amount of air at the first pressure level and the first temperature level. This air is then particularly subjected to cooling to a fourth temperature level. The fourth temperature level can in particular be between -120 and -150 ° C. In combination with the pressure used, that is to say the first pressure level, it is selected in such a way that the outlet conditions explained are set at a turbine used to expand the third process flow.

In the context of the present invention, the air provided at the first pressure level, which is used to form the first and the second process flow, is, as mentioned, part of a total amount of air that is generated using an air compressor and a booster which is arranged in parallel with the air compressor , is brought to the first pressure level. The air that is used to form the third process flow is also part of this total air volume. The booster is coupled to an expansion machine used in the expansion of the third process stream and is driven by means of this expansion machine. The drive of the booster can only or in part using this expansion machine, in other words, an additional motor drive can also be used, for example. The coupling can also take place with the interposition of a brake, so that not all of the drive power that is released when the third process stream is released is used to drive the booster. In particular, the air compressor can be driven exclusively by means of external energy, ie without the use of power that is released when a process flow of the air separation plant is expanded, and the booster can be driven exclusively by expansion of a corresponding process flow.

It should be made clear again that within the scope of the present invention, a first portion of the total amount of air is always passed through the air compressor and not through the booster, and that a second portion of the total amount of air is passed through the booster and not through the air compressor. Using the total amount of air, the first, second and third process streams are formed; however, in particular another process stream can also be formed in the form of a further throttle stream, the air of which can be cooled in a main heat exchanger of the air separation plant, liquefied and fed into the high pressure column. For further details, reference is made to the specialist literature explained at the beginning.

The second portion of the total amount of air advantageously comprises 5% to 25% of the total amount of air and the first portion of the total amount of air comprises in particular the remainder of the total amount of air. These proportions are also based on standard volume flows. In the context of the present invention, in the evaluated case, the first portion can in particular comprise 13% to 17% of the total air volume. By compressing this portion of the total amount of air in a booster, a cost reduction for the air compressor can be achieved within the scope of the present invention. The air compressor can in particular be designed in one stage in this way. In particular, it can be supplied with air which comes from an air supply network and which is already compressed to a certain pressure level in this air supply network. However, the air compressor can also be connected downstream of further compressor stages, for example as a compressor stage.

In particular, it should be emphasized that within the scope of the present invention, the booster is not used to compress an amount of air that has already been purified. Rather, within the scope of the present invention, the booster is used in particular upstream of a corresponding cleaning system. In other words, according to a particularly preferred embodiment, the total amount of air is compressed using the air compressor and the booster in the water-containing state and then, i. after compaction, pre-cooled and dried. As already mentioned, the total amount of air can be fed to the air compressor and the booster at a pressure level above atmospheric. The total amount of air can be provided externally to this above-atmospheric output pressure level or compressed to this output pressure level in the air separation plant.

As explained several times, the present invention can be used in particular in air separation processes in which no or only extremely small amounts of liquid air products are formed. In other words, according to a particularly preferred embodiment, the present invention comprises that an amount of one or more air products corresponding to a maximum of 2% of the total amount of air is discharged in liquid form from the air separation plant. The diversion can also take place continuously or only temporarily. The maximum amount can in particular also be 1.5%, 1% or 0.5%.

In the context of the present invention, in particular two or more than two oxygen-rich, gaseous air products are provided. A first of these oxygen-rich, gaseous air products can be provided by internal compression, as explained several times above. For this purpose, oxygen-rich liquid is typically withdrawn from the low-pressure column, increased in pressure using an internal compression pump and converted into the gaseous or supercritical state in a main heat exchanger of the air separation plant under the pressure to which it was pressure increased by means of the internal compression pump. A second of these oxygen-rich, gaseous air products is withdrawn in gaseous form from the low-pressure column in the context of the present invention, in particular without increasing the pressure.

The present invention also relates to an air separation plant for providing one or more oxygen-rich, gaseous air products. Regarding the features of the air separation plant proposed according to the invention, express reference is made to the corresponding independent patent claim. A corresponding air separation plant benefits from the advantages explained above with regard to the method according to the invention and its preferred configurations, to which reference is therefore expressly made. In particular, such an air separation plant is set up to carry out a method according to one of the configurations explained above, and has means set up for this purpose.

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

• Figur 1 veranschaulicht eine Luftzerlegungsanlage gemäß einer besonders bevorzugten Ausführungsform der Erfindung.
• Figur 2 veranschaulicht eine Luftzerlegungsanlage gemäß einer besonders bevorzugten Ausführungsform der Erfindung.
• Figur 3 veranschaulicht eine Luftzerlegungsanlage gemäß einer besonders bevorzugten Ausführungsform der Erfindung.

Brief description of the drawings

• Figure 1 illustrates an air separation plant according to a particularly preferred embodiment of the invention.
• Figure 2 illustrates an air separation plant according to a particularly preferred embodiment of the invention.
• Figure 3 illustrates an air separation plant according to a particularly preferred embodiment of the invention.

In the figures, structurally or functionally corresponding elements are illustrated with identical reference symbols and are not explained repeatedly for the sake of clarity.

Detailed description of the drawings

In the Figures 1 to 3 Air separation plants according to preferred embodiments of the invention are illustrated, respectively labeled 100, 200 and 300. The air separation plants 100, 200 and 300 have a number of identically designed components, but in practice they can also be structurally designed differ from each other. The air separation plant 100 according to FIG Figure 1 explained; regarding the in the Figures 2 and 3 air separation plants 200 and 300 illustrated below, only the distinguishing features are discussed.

In the in Figure 1 Air A, which has already been pressurized outside the system 100, is provided in the form of a feed air flow a in the air separation plant 100 illustrated. This air can, for example, come from a supply network and, for example, be at a pressure of approx. 6 bar. Deviating from the representation according to Figure 1 However, the air A can also be pressurized within the air separation plant 100.

The feed air A of the feed air flow a is divided into two partial flows b and c after precooling (required in certain cases) in a heat exchanger (not specifically designated), the partial flow b being compressed in an air compressor 101 and the partial flow c in a booster 102. In the parlance used here, a pressure level upstream of the air compressor 101 and the booster 102 is referred to as the “initial pressure level”, while a pressure level downstream of the air compressor 101 and the booster 102 is referred to as the “first pressure level”. The air compressor 101 is preferably designed in one stage. As explained above, the predominant portion of the feed air A is compressed in the form of the material flow b in the air compressor 101, but a smaller portion is compressed in the booster 102 in parallel.

After the compression, the partial flows b and c are combined in the example shown to form a collective flow d, which is cooled in a basically known manner in a pre-cooling device 103 using cooling water (flow B, return C). The cooled feed air flow is further designated by d and then fed to a cleaning device 104, for example comprising a pair of adsorber containers operated in alternation.

The stream of material which has been freed from water and carbon dioxide, but which is still referred to here as d, is divided into several substreams. A substream e is fed to a main heat exchanger 105 of the air separation plant 100 (at the first pressure level and a temperature level referred to here as the “first temperature level”). The partial flow e is the main heat exchanger 105 taken at a temperature level, which is referred to here as the "second temperature level". The partial flow e is initially still at the first pressure level. The partial flow e is subjected to compression in a cold booster 106 at the first pressure level and the second temperature level. This brings it to a higher pressure level, which is referred to here as the "second pressure level".

The temperature of the partial flow e increases due to the compression due to the heat of compression introduced, so that the partial flow e is fed back to the main heat exchanger 105 at an intermediate temperature level above the second temperature level. The partial flow e is then further cooled in the main heat exchanger 105, specifically to a temperature level which is referred to here as the “third temperature level”. At the second pressure level and the third temperature level obtained by the cooling, the substream e is then fed into a separator 107 and subjected to a phase separation.

In the example shown here, a gas phase in the form of a material flow f and a liquid phase in the form of a material flow g are withdrawn from the separator 107. The material flow f is referred to here as the “first process flow”, and the material flow g is correspondingly referred to as the “second process flow”. The first process stream comprises non-liquefied, pressurized air as a result of the treatment explained above, and the second process stream g comprises pressurized and liquefied air.

The first process stream f is expanded in an expansion turbine 108 and fed into a high pressure column 111 of the air separation plant 100. The expansion turbine 108 is operated, as explained several times, in such a way that a liquid portion forms at its outlet to a defined extent as explained above. The expansion in the expansion turbine 108 takes place to an operating pressure level of the high pressure column 111 or a pressure level present in the high pressure column 111 at the feed point.

The second process stream g is in the in Figure 1 illustrated example again supplied to the main heat exchanger 105 and removed from this at the cold end. The second process stream g is passed through the main heat exchanger 105 with a partial stream h of the material stream d, which passes from the warm to the cold end and through this was liquefied, combined after the second process stream g and the substream h were each expanded in corresponding expansion devices, for example expansion valves, which are not separately designated here. The expansion also takes place to a pressure level in the high pressure column 111 or a pressure level which is present at a feed point into the high pressure column 111. A material flow formed from the second process flow g and the substream h is designated as a collective flow with the reference symbol i.

In the air separation plant 100 according to Figure 1 air is also blown into a low-pressure column 112 of the air separation plant 100, for which a basically known Lachmann turbine 109 is used. The Lachmann turbine 109 is an expansion turbine that is used in the in Figure 1 illustrated embodiment of the air separation plant 100 is mechanically coupled to the booster 102 already explained above. The air expanded in the expansion turbine 109 is a partial flow k of the material flow d, which was previously cooled to an intermediate temperature level in the main heat exchanger 105 (referred to here as the “fourth temperature level”). The air of substream k expanded in expansion turbine 109 is fed (see link 2) into low-pressure column 112, as already mentioned.

In the example shown, the air separation plant 100 has a crude argon column 113 and pure argon column 114 in addition to the high pressure column 111 and the low pressure column 112 in a rectification column system, which is designated as a whole by 110. Operation of the rectification column system 110 is known in the art.

Air separation plants of the type shown are often described elsewhere, for example at Häring (see above) Figure 2 .3A. For detailed explanations of the structure and mode of operation, reference is therefore made to the corresponding specialist literature. An air separation plant for using the present invention can be designed in the most varied of ways.

In the example shown, two gaseous oxygen-rich air products are provided at different pressure levels. To provide a gaseous, oxygen-rich air product at just above atmospheric pressure level, ie the pressure level at which the low-pressure column 112 is operated is, gaseous fluid is withdrawn from the low-pressure column 112 above its bottom in the form of a stream I, which is heated in the main heat exchanger 105 without further pressure-influencing measures and is provided as a corresponding air product, which is additionally denoted by D here.

To provide the pressurized, oxygen-rich, gaseous air product, bottom liquid is withdrawn from the low-pressure column 112 in the form of a material flow m, which in the example shown can also be carried out in part as liquid oxygen, here additionally designated with K, in the form of a material flow n from the air separation plant 100 . This is preferably not the case or only to a small extent within the scope of the present invention. To provide the pressurized, oxygen-rich, gaseous air product, the remainder of this is brought to a higher pressure level, referred to here as the "discharge pressure level", using an internal compression pump 115, and transferred in the main heat exchanger 105 to the gaseous or, depending on the pressure level, supercritical state in the form of a material flow o as a corresponding air product, which is also designated here with E.

In the in Figure 1 In addition, pressurized, gaseous, argon-rich fluid is provided as air product F as shown in the air separation plant 100 shown. For this purpose, liquid is withdrawn from the pure argon column 114 in the form of a material flow p and, comparable to the material flow o, is brought to a higher pressure level in an internal compression pump 116, converted to a gaseous or supercritical state in the main heat exchanger 105 and provided in the form of the corresponding air product F.

As is known in the field of air separation, the air separation plant 100 can also be used to provide low-pressure nitrogen in the form of an air product G, nitrogen from the top of the high-pressure column 111 in the form of an air product H and impure nitrogen from the top of the low-pressure column 112 in the form of an air product I. Further impure nitrogen can be withdrawn from the low-pressure column 112 in the form of a stream r and used, for example, as a regeneration gas in the cleaning device 104 or in the pre-cooling device 103 and then blown off to the atmosphere X. By discharging Liquid can theoretically, but preferably not within the scope of the present invention, a liquid nitrogen product L be provided.

The air separation plant 200 according to Figure 2 differs from air separation unit 100 according to Figure 1 in particular because the second process stream g is not further cooled in the main heat exchanger 105 before it is expanded and fed into the low-pressure column.

In the air separation plant 300, which is in Figure 3 is illustrated is in contrast to the air separation plant 100 of FIG Figure 1 the partial flow k expanded in the expansion turbine 109 is only fed to the pressure level of the high pressure column 111; the partial flow k is therefore not blown into the low pressure column but is fed to the high pressure column 111 as a further turbine flow.

Claims (15)

A method for producing one or more oxygen-rich, gaseous air products, in which a first process stream, which mainly or exclusively comprises pressurized non-liquefied air, and a second process stream, which predominantly or exclusively comprises pressurized liquefied air, are formed in an air separation plant (100-300) , and in which the first and the second process stream are separately subjected to an expansion to an operating pressure level of a high pressure column (111) of the air separation plant (100-300) and partially or completely fed into the high pressure column (111), characterized in that to form the first and the second process stream of air is used, which is provided as part of a total air volume at a first pressure level and a first temperature level, the total air volume using an air compressor (101) and a booster (102), which runs parallel to the air compressor hter (101) is arranged, is brought to the first pressure level, wherein the booster (102) is coupled to an expansion turbine (109) used in the expansion of a third process stream and is driven by this. Method according to claim 1, in which the air that is used to form the first and the second process stream is successively cooled to a second temperature level, compressed to a second pressure level, cooled to a third temperature level, and a liquid phase is obtained and a gas phase is subjected to phase separation, wherein the second temperature level is -120 ° C to -150 ° C, the first process stream is formed using at least a part of the gas phase, the second process stream is formed using at least a part of the liquid phase, the The first process stream is fed to the expansion at the second pressure level and the third temperature level, and the second pressure level and the third temperature level are selected such that when the first process stream is expanded to the operating pressure level of the high pressure column (111), a liquid content of 5% to 15 %, based on the entire first perc essstrom, forms. Method according to Claim 2, in which a third process stream, which comprises predominantly or exclusively pressurized, non-liquefied air, is formed, the third process stream being subjected to expansion to an operating pressure level of a low-pressure column (112) of the air separation plant (100, 200) and partially or completely in the low-pressure column (112) is fed in, or is subjected to an expansion to the operating pressure level of the high-pressure column (111) of the air separation plant (300) and partially or completely fed into the high-pressure column (111), the third process stream being supplied to the expansion, in particular at a temperature level , which is more than 10 K above the third temperature level and differs by less than 10 K from the second temperature level. Method according to Claim 1 or 2, in which air is used to form the third process flow, which air is provided at the first pressure level and the first temperature level and is subjected to cooling to a fourth temperature level. Method according to Claim 4, in which a first portion of the total amount of air is passed through the air compressor (101) and not through the booster (102), and in which a second portion of the total amount of air is passed through the booster (102) and not through the air compressor (101 ) to be led. The method of claim 5, wherein the second portion of the total amount of air comprises 5% to 25% of the total amount of air and the second portion of the total amount of air comprises the remainder of the total amount of air. Method according to one of Claims 4 to 6, in which the total amount of air is compressed in a water-containing state using the air compressor (101) and the booster (102) and is then jointly pre-cooled and dried. Method according to one of Claims 4 to 7, in which a single-stage air compressor is used as the air compressor (101). Method according to one of Claims 4 to 8, in which the total amount of air is supplied to the air compressor (101) and the booster (102) at a superatmospheric output pressure level. Method according to Claim 9, in which the total amount of air is provided externally to the system at the above-atmospheric output pressure level or is compressed to the output pressure level in the air separation unit. Method according to one of Claims 4 to 10, in which an amount of one or more air products corresponding to a maximum of 2% of the total amount of air is discharged continuously or only temporarily in liquid form from the air separation plant (100-300). Process according to one of claims 2 to 10, in which two or more than two oxygen-rich, gaseous air products are provided, a first of the oxygen-rich, gaseous air products being provided by internal compression, and a second of the oxygen-rich, gaseous air products being provided without pressure increase from the low-pressure column (112) is taken in gaseous form. Method according to one of the preceding claims, in which the air used to provide the first and the second process stream is cooled to the second temperature level at the first pressure level and the first temperature level, the compression to the second pressure level at the second temperature level and the first pressure level, the cooling to the third temperature level at the second pressure level and a temperature level below the second temperature level, and the phase separation at the second pressure level and the third temperature level. Air separation plant (100-300) for providing one or more oxygen-rich, gaseous air products, wherein means are provided which are set up to include a first process stream that predominantly or exclusively comprises pressurized non-liquefied air, and a second process stream that predominantly or exclusively liquefies pressurized air Comprises air, and the first and second process streams separately from one another to a relaxation to an operating pressure level of a high pressure column (111) of the air separation plant (100-300) and then partially or completely fed into the high pressure column (111), characterized in that means are provided which are set up to form the to use first and second process stream air, which is provided as part of a total amount of air at a first pressure level and a first temperature level, an air compressor (101) and a booster (102), which is arranged parallel to the air compressor (101), being provided which are set up to bring the total amount of air to the first pressure level, wherein the booster (102) is coupled to an expansion turbine (109) set up to expand a third process stream and is set up to be driven by this. Air separation plant (100-300) according to Claim 14, which is set up to carry out a method according to one of Claims 1 to 13.

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