WO2020164799A1

WO2020164799A1 - Method and system for providing one or more oxygen-rich, gaseous air products

Info

Publication number: WO2020164799A1
Application number: PCT/EP2020/025039
Authority: WO
Inventors: Dimitri GOLUBEV
Original assignee: Linde Gmbh
Priority date: 2019-02-13
Filing date: 2020-01-30
Publication date: 2020-08-20
Also published as: EP3924677A1; EP3696486A1

Abstract

The invention relates to a high-pressure (HAP) air separation plant (100-300). In order to form a first, unliquefied process stream and a second, liquefied process stream which are separately decompressed to a pressure level of the high-pressure column (111) and fed into said column, gaseous and liquid portions of air are used, said air being provided at a first pressure level and a first temperature level and being successively cooled to a second temperature level, compressed to a second pressure level, cooled to a third temperature level, and subjected to a phase separation process. The first process stream is supplied to the decompression process at the second pressure level and the third temperature level, and the second pressure level and the third temperature level are selected so as to form a liquid portion of 5% to 15%, based on the entire first process stream, during the decompression of the first process stream to the operating pressure level of the high-pressure column (111). Without being compressed further, further air is cooled down, decompressed using turbines, and fed into the rectification column system (110). Only process streams provided using the rectification column system (110) are used for cooling. The invention also relates to an air separation plant (100-300).

Description

description

Process and system for providing one or more oxygen-rich.

gaseous air products

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, especially Section 2.2.5, "Cryogenic Rectification".

As used herein, the term "air product" is intended to refer to a fluid 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 composition that differs from that 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 that

are conventionally designed as two-column systems, in particular as classic Linde double-column systems, but also as three or

Multi-column systems can be formed. 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 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 of 4 to 7 bar, in particular about 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.

So-called main (air) compressors / booster (Main Air Compressor / Booster Air Compressor, MAC-BAC) processes or so-called

High air pressure (HAP) processes are used. The main / booster processes are more like

More conventional methods, high air pressure methods, have been used more and more recently as alternatives. The present invention is used in connection with HAP processes, so that the following explanations in this regard apply generally and also to the present invention. Due to the significantly lower costs - main and booster compressors are in a sense in one

Machine integrated - and with comparable efficiency, high-air pressure processes can represent an advantageous alternative to 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 shown, for example, by Häring (see above) in FIG. 2.3A. In 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 that is substantially, that is, by at least 3, 4, 5, 6, 7, 8, 9 or 10 bar, and for example up to 14, 16 , 18 or 20 bar, is above the pressure at which the high pressure column is operated. High-air pressure methods are known, for example, from EP 2 980 514 A1 and EP 2 963 367 A1.

High air pressure procedures typically come with what is called the

Internal compression (IV, IC) is used. 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 the

A cryogenic, liquid air product is removed from the rectification column system, subjected to a pressure increase to a product pressure, and at which the product pressure is converted into the gaseous or supercritical state by heating.

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 over an alternatively also possible external compression and is e.g. at Häring (see above) in Section 2.2.5.2, "Internal Compression". Attachments to

Low-temperature decomposition of air, in which internal compression is used, is also shown in US 2007/0209389 A1 and in WO 2015/127648 A1.

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

Provision of one or more oxygen-rich, gaseous air products and a corresponding system with the respective characteristics of the independent

Claims before. 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, in a main compressor / booster process only part of this input air is compressed to a pressure level that is significantly above the (operating) pressure level of the high pressure column. In contrast, in a high-air pressure process, as is the subject of the present invention, the entire amount of feed 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 in comparison to the

However, the main air compressor or the booster only compresses to a relatively small extent. A booster can also be present in a high-air pressure process, but this compresses a subset of the

The amount of air used is then based on 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 are those

The turboexpander (the expansion turbine) and the turbo compressor (the booster) are mechanically coupled, with the coupling having the same speed (for example via a common shaft) or different speed (for example via a

intermediate gear) can take place.

A “cold compressor” or “cold booster” should be understood here to mean a compressor or booster, the fluid at a temperature level below the

Ambient temperature, especially 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%. Is here

For example, if we talk about nitrogen, it can be a pure gas, but also a gas rich in nitrogen.

To characterize pressures and temperatures, the

The terms “pressure level” and “temperature level” are used, 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 vary

typically in certain ranges which are, 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 methods are often after the so-called

Liquid performance or according to the ratio of internally compressed products

Liquid products classified and differentiated. The liquid output denotes the amount of air products that are carried out in liquid form from the system or a corresponding process, i.e. with no evaporation or

Pseudo evaporation takes place. With such products, no

Feed streams in the plant or the process are 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. With a low liquid power, a so-called

Cold boosters can be used to increase 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 used in a high-air pressure process in which gaseous oxygen is to be produced without any (significant) liquid production. The peculiarity lies in 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 just those given here

Orders of magnitude limited.

Table 1

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, one includes

Air separation plant, as in one embodiment of the invention

is proposed, or a corresponding method, one as in one

Main compressor / post-compressor process, the usual interconnection, but in which the entire amount of air used is still in the usual way for a high-air pressure process Pressure level is brought, and in which a blow-in turbine (Lachmann turbine) is also provided. As explained below, however, in the context of the present invention, instead of a blow-in 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. For the terms "Claude turbine" and "Lachmann turbine", reference is made 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 producing one or more oxygen-rich, gaseous air products using an air separation plant which has a rectification column system with a high pressure column. A total amount of feed air fed to the rectification column system is compressed to a first pressure level which is at least 3 bar (further values have already been mentioned in the introduction and are also suitable for the present invention) above an operating pressure level at which the high pressure column is operated. A first process stream, which comprises predominantly or exclusively pressurized, non-liquefied air, and a second process stream, which comprises predominantly or exclusively pressurized liquefied air, are formed, and the first and second process streams are released separately from one another to the operating pressure level of the

Subjected high pressure column and partially or completely fed into the high pressure column. In this context, it is understood that, after the expansion, further material flows are respectively fed to the first and the second process flow and, together with these, to the high-pressure column

can be fed in. 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 thus a so-called turbine flow, as it is also used in known methods of

Air separation is formed. The appropriate to relax a The expansion turbine used in the 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, a so-called liquid turbine or a so-called sealing fluid expander (Dense Liquid Expander, DLE), as is known from the prior art, can also be 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 in operation. Therefore, as mentioned, the term “operating pressure level” denotes the pressure at the respective feed point or a corresponding pressure range. Specific values which also apply to the present invention were mentioned in the introduction.

According to the invention it is provided that to form the first and the second process stream, a portion of the input air quantity is used, which is provided at the first pressure level and a first temperature level and successively cooling to a second temperature level, compression to a second pressure level, and 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 in the context of the present invention is in particular -120 to -150 ° C; the compression on the second

The pressure level is therefore based on a correspondingly low one 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 present invention 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 the second process stream after cooling to the second temperature level is compressed, 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 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 present invention it is provided that the first process stream using at least part of the gas phase from the mentioned

Phase separation is formed, and that the second process stream is formed using at least a portion of the liquid phase that is formed in the phase separation. 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.

The first process stream is the relaxation to the pressure level of the

High pressure column supplied to 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 when the first process stream is expanded to the operating pressure level of the

High pressure column forms a liquid content 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 within the scope of the present invention with a defined (dew) state at the turbine inlet, which leads to a corresponding Liquid fraction at the turbine outlet leads. By means of such measures, the process potential can be optimally exhausted 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 according to the invention for expansion of the first process stream is to be considered in particular in connection with an injection turbine used or an expansion turbine that expands a further turbine stream, as explained below.

According to the invention, in order to form at least one third process stream, which is subjected to an expansion using an expansion turbine and is fed into the rectification column system, a further part of the

Feed air used, which is at the first pressure level and the first

Temperature level provided and is subjected to cooling without further compression. It is also possible to provide further process streams that are not subjected to any further compression, but are used for other purposes, for example fed into the rectification column system. Some of these are explained below.

If the method proposed according to the invention were to be considered conventionally, i.e. with the usual optimization of the turbine inlet temperatures, one would find that the outlet state in the case of a corresponding injection turbine is heavily pre-liquefied and the inlet state of the turbine used to expand the first process flow is only relative shows slight 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, to convey it to a

Pre-liquefaction upstream of the relaxation of the first process stream

used expansion turbine could come. With such a

Pre-liquefaction, damage to the inlet nozzles in a corresponding expansion turbine and the impeller surface are to be feared. Therefore, it is also proposed in the context of the present invention, the

Entry state of a corresponding third process stream into the injection turbine, ie a Lachmann turbine, or a turbine, the corresponding air into the

Relieved high pressure column, i.e. a Claude turbine, to be set higher or to be selected in such a way that no liquid is produced at its outlet. 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 mentioned turbine is practically formed when the first process flow is relaxed.

An essential feature of the present invention is that the turbine flow, i. 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.

In all cases, within the scope of the present invention, in addition to the second process stream, yet another process stream can also be combined in one

Main heat exchanger of the air separation plant are liquefied and partially or completely expanded into the high pressure column, in particular together with the second process stream, wherein expansion can take place separately from the second process stream or together with it.

As already explained, in the context of the present invention, an injection turbine or Lachmann turbine is advantageously used or a corresponding material flow is formed. However, a second turbine flow can also be provided or air can be expanded in a Claude turbine. In other words, according to particularly preferred refinements, the present invention includes that the third process stream, which comprises predominantly or exclusively pressurized, non-liquefied air, the (turbine) expansion to an operating pressure level

Low-pressure column which is subjected to the rectification column system and partially or completely fed into the low-pressure column, or an expansion is subjected to the operating pressure level of the high pressure column and is 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 portion of the liquid that consists of

Balance sheet reasons is required, is within the scope of the present invention

instead, as mentioned earlier, in the for relaxation of the first

Process flow used relaxation turbine formed.

In the context of the present invention, the formation of the third

Process stream used air, which is provided at the first pressure level and the first temperature level. This air is then subjected to cooling to a fourth temperature level. The fourth temperature level can in particular be between -120 and -150 ° C. It will, in combination with the

pressure used, that is to say the first pressure level, because no further compression takes place, 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 total amount of air is advantageously brought to the first pressure level using an air compressor and a booster which is arranged parallel to the air compressor. The air that is used to form the third process stream is also part of this

Total air volume. The booster is coupled in particular to an expansion machine used in the expansion of the third process stream and is driven by means of this expansion machine. The booster can be driven exclusively or partially using this expansion machine, in other words, for example, an additional motor drive can also be used. 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. It should be clarified again that in the context of the present invention according to the embodiment just explained, a first portion of the total amount of air is 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, there can also be another in particular

Process flow can be formed in the form of a further throttle flow, the air of which can be cooled, liquefied and fed into the high-pressure column in a main heat exchanger of the air separation plant. 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 up

Standard volume flows related. The first part can be part of the

present invention in the evaluated case in particular 13% to 17% of the

Include total air volume. By compressing this share of the

Total amount of air in a booster can be achieved within the scope of the present invention, a cost reduction for the air compressor. 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 compressed using the air compressor and the booster in a water-containing state and then, ie after compression, pre-cooled and dried. As already mentioned, the total amount of air can be fed to the air compressor and the booster at a superatmospheric pressure level. The 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 is used in air separation processes in which no or only extremely small amounts of liquid air products are formed. In other words, the present invention includes that at any point in time a maximum of 2% of the total air amount corresponding to one or more air products liquid from the

Air separation plant is diverted. 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 transferred to 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.

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 above the second temperature level, and the phase separation at the second pressure level and the third temperature level. 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 previous information on

Method according to the invention and its preferred embodiments explained advantages, which are therefore expressly referred to. 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.

Brief description of the drawings

Figure 1 illustrates an air separation plant according to one particular

preferred embodiment of the invention.

Figure 2 illustrates an air separation plant according to one particular

preferred embodiment of the invention.

Figure 3 illustrates an air separation plant according to one particular

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 Figures 1 to 3 are designated by 100, 200 and 300, respectively

Air separation plants according to preferred embodiments of the invention illustrated. 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. 1 is first explained below; With regard to the air separation plants 200 and 300 illustrated in FIGS. 2 and 3, only the distinguishing features are discussed below.

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

Air separation unit 100 can be pressurized.

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”. Of 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 partial stream e is a main heat exchanger 105 (at the first pressure level and a temperature level referred to here as the “first temperature level”)

Air separation unit 100 supplied. 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. As a result, it is brought to a higher pressure level, which here is the "second"

Pressure level "is designated.

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

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”, the material flow g

accordingly as "second process stream". 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, as explained several times, operated in such a way that a liquid component forms at its outlet to a defined extent as explained above. The expansion in the expansion turbine 108 takes place on one

Operating pressure level of the high pressure column 111 or a pressure level present in the high pressure column 111 at the feed point.

In the example illustrated in FIG. 1, the second process stream g is again fed to the main heat exchanger 105 and removed from it 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 each in corresponding expansion devices, for example

Relaxation valves, which are not specifically designated here, were relaxed. 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 FIG. 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 which, in the embodiment of the air separation plant 100 illustrated in FIG. 1, 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 that was previously on in the main heat exchanger 105

Intermediate temperature level was cooled (referred to here as "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 in addition to

High pressure column 111 and the low pressure column 112 in one

Rectification column system, which is designated as a whole by 110, a

Crude argon column 113 and pure argon column 114. The operation of the

Rectification column system 110 is known from the prior art.

Air separation plants of the type shown are often described elsewhere, for example in Häring (see above) for 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 employing the present invention can be based on

be designed in different 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 to 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 is bottom liquid of the low pressure column 112 in the form of a

Material flow m taken, which in the example shown can also be carried out to a proportion as liquid oxygen, here additionally designated by 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 it is pumped using an internal compression pump

115 brought to a higher pressure level, here referred to as "delivery pressure level", transferred in the main heat exchanger 105 to the gaseous or, depending on the pressure level, supercritical state and executed in the form of a material flow o as a corresponding air product, which is also referred to here with E.

In the air separation plant 100 shown in FIG

pressurized, gaseous, argon-rich fluid provided as air product F. 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, in an internal compression pump

116 brought to a higher pressure level, 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 from the field of air separation, the

Air separation plant 100 can also 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 of Figure 2 differs from

Air separation plant 100 according to FIG. 1, in particular, in that the second process stream g prior to its expansion and being fed into the

Low pressure column is not further cooled in the main heat exchanger 105.

In the air separation plant 300, which is illustrated in FIG. 3, in contrast to the air separation plant 100 according to FIG. 1, there is a feed of the in the

Expansion turbine 109 expanded substream k only provided to the pressure level of the high pressure column 111, the substream k is therefore not in the

Low pressure column blown in, but as a further turbine stream of the

High pressure column 111 fed.

Claims

1. Process for the production of one or more oxygen-rich, gaseous

Air products using an air separation unit (100-300) which is a

Having rectification column system (110) with a high pressure column (111) in which

- One of the rectification column system (110) fed as a whole

Feed air volume is compressed to a first pressure level which is at least 3 bar above an operating pressure level on which the

High pressure column (111) is operated,

- In the air separation plant (100-300) a first process stream, the

comprises predominantly or exclusively pressurized non-liquefied air, and a second process stream comprising predominantly or exclusively pressurized liquefied air are formed, and

- the first and the second process stream separately from one another

Subjected to expansion to the operating pressure level of the high pressure column (111) and partially or completely fed into the high pressure column (111), characterized in that

- To form the first and the second process stream, part of the

Feed air quantity is used, which is provided at the first pressure level and a first temperature level and successively cooling to a second temperature level of -120 ° C to -150 ° C, compression to a second pressure level, cooling to a third temperature level, and maintaining a liquid phase and a gas phase

Phase separation is subjected to the first process stream using at least a portion of the

Gas phase is formed, the second process stream is formed using at least a portion of the liquid phase, and the first Process flow of relaxation is fed to the second pressure level and the third temperature level,

- 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 process stream, is formed,

- To form at least one third process stream, which is subjected to an expansion using an expansion turbine (109) and fed into the rectification column system (110), a further part of the feed air quantity is used, which is provided at the first pressure level and the first temperature level and without any further Compaction is subjected to cooling,

the cooling of the first, the second and at least the third

Process stream with the exclusive use of others

Process streams provided using the rectification column system (110) is performed, and

- At any point in time, a quantity of one or more air products corresponding to a maximum of 2% of the total air volume is discharged from the air separation plant (100-300) in a liquid state.

2. The method according to claim 1, in which the third process stream comprises predominantly or exclusively non-liquefied air, the third process stream being subjected to expansion to an operating pressure level of a low-pressure column (112) of the rectification column system (110) and partially or completely fed into the low-pressure column (112) is, or an expansion to the operating pressure level of the high pressure column (111) which is subjected and partially or completely fed into the high pressure column (111).

3. The method according to claim 2, wherein the third process stream of relaxation is fed to a temperature level that is more than 10 K above the third Temperature levels and is less than 10 K from the second

Temperature level differs.

4. The method of claim 2 or 3, wherein the to form the third

Process stream used air is subjected to cooling to a fourth temperature level.

5. The method according to any one of claims 3 to 4, in which the total amount of air is brought to the first pressure level using an air compressor (101) and a booster (102) which is arranged parallel to the air compressor (101), the booster (102) is coupled to an expansion turbine (109) used in the expansion of the third process stream and is driven by this.

6. The method of claim 5, wherein a first portion of the total amount of air through the air compressor (101) and not through the booster (102), and in which a second portion of the total amount of air through the booster (102) and not through the air compressor (101) is performed.

7. The method of claim 6, wherein the second portion of the total amount of air comprises 5% to 25% of the total amount of air and the first portion of the total amount of air comprises the remainder of the total amount of air.

8. The method according to any one of claims 5 to 7, in which the total amount of air is compressed using the air compressor (101) and the booster (102) in a water-containing state and then jointly pre-cooled and dried.

9. The method according to any one of claims 5 to 8, in which a single-stage air compressor is used as the air compressor (101).

10. The method according to any one of claims 5 to 9, wherein the total amount of air is supplied to the air compressor (101) and the booster (102) at a superatmospheric output pressure level.

11. The method according to claim 10, 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.

12. The method according to any one of the preceding claims, in which two or more than two oxygen-rich, gaseous air products are provided, wherein a first of the oxygen-rich, gaseous air products is provided by internal compression, and wherein a second of the oxygen-rich, gaseous air product without pressure increase from the low-pressure column (112) is taken in gaseous form.

13. The method according to any 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 above the second temperature level, and the phase separation is fed to the second pressure level and the third temperature level.

14. Air separation plant (100-300), which has a rectification column system (110) with a high pressure column (111) and is set up to provide one or more oxygen-rich, gaseous air products, wherein

- Means are provided which comprise a compressor (101) and for it

are set up to compress a total amount of feed air supplied to the rectification column system (110) to a first pressure level which is at least 3 bar above an operating pressure level at which the high pressure column (111) is operated,

Means are provided which are set up for a first

Process stream, which comprises predominantly or exclusively pressurized non-liquefied air, and a second process stream, the predominantly or exclusively pressurized liquefied air comprises, to form, and

- Funds are provided that are set up for the first and the first

to subject the second process stream separately from one another to an expansion to the operating pressure level of the high pressure column (111) and to feed it partially or completely into the high pressure column (111), characterized in that

- Means are provided which are set up to use a portion of the feed air quantity that is at the first pressure level and a first pressure level to form the first and the second process stream

Temperature level is provided, and this air is successively cooled to a second temperature level of -120 ° C to -150 ° C, a compression to a second pressure level, a cooling to a third temperature level, and a phase separation while maintaining a liquid phase and a gas phase subjugate

- Means are provided which are set up to form the first process stream using at least part of the gas phase and the second process stream using at least a part of the liquid phase and to supply the first process stream to the expansion at the second pressure level and the third temperature level

- Means are provided which are set up to provide the second pressure level and the third temperature level in such a way that when the first process stream is expanded to the operating pressure level of the high pressure column (111), a liquid proportion of 5% to 15%, based on the entire first Process stream, forms,

- Means are provided which are set up for the formation of at least one third process stream, for its relaxation a

Expansion turbine (109) is provided, and in the

Rectification column system (110) is fed, another part of the To use the amount of feed air, which is provided at the first pressure level and the first temperature level and is subjected to cooling without further compression, means are provided which are set up to cool the first, the second and at least the third process stream with the exclusive use of further process streams using the

Rectification column system (110) are provided, means are provided which are set up for a maximum of 2% of the total air amount of one or more air products in the liquid state from the

Air separation plant (100-300) to be diverted.