EP2824407A1 - Method for generating at least one air product, air separation plant, method and device for generating electrical energy - Google Patents

Abstract

The invention relates to a method for producing at least one air product using an air separation plant (100) comprising a main air compressor (10), a main heat exchanger (20) and a distillation column system (30), wherein at least one first air compressor (10) is provided by the main air compressor (10) Compressed air flow (a) is provided at a first pressure level and a first partial flow (b) of the first compressed air flow (a) at the first pressure level of a first passage (21) of the main heat exchanger (20) is supplied proposed. Furthermore, a second partial flow (c) of the first compressed air flow (a) in a first operating mode at the first pressure level and in a second operating mode at a second pressure level which is higher than the first pressure level, a second passage (22) of the main heat exchanger (20 ), wherein the second partial flow (c) of the first compressed air flow (a) in the second operating mode at least by means of a turbine driven Nachverdichters (41) increases pressure to the second pressure level and downstream of the main heat exchanger (20) in an expansion turbine (42) is relaxed, the is used for driving the turbine-driven post-compressor (41). A corresponding air separation plant (100) and a method and a device for generating electrical energy are likewise provided by the present invention.

Description

The invention relates to a method for producing at least one air product, an air separation plant and a method and a device for generating electrical energy according to the preambles of the independent claims.

State of the art

In known processes for generating electrical energy, for example the known oxyfuel process and so-called combined gasification combined cycle (IGCC) processes, oxygen or oxygen-enriched gas mixtures, for example for combustion or partial oxidation, are required. To provide the oxygen or corresponding oxygen-enriched gas mixtures, methods and devices for the cryogenic separation of air can be used, as for example Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, chapter 4 (pages 281 to 337 ) are known.

In such processes and devices (referred to herein for short as "air separation plants"), distillation column systems are used, which may be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three-column or multi-column systems. Furthermore, devices for obtaining further air components, in particular the noble gases krypton, xenon and / or argon, may be provided.

Methods and devices for generating electrical energy should be designed for large load ranges and fast load changes, in order to be able to intercept power fluctuations, such as may result from the availability or unavailability of other energy feeders. Also, air separation plants that supply oxygen or corresponding gas mixtures for this purpose should allow for a correspondingly flexible mode of operation.

Even conventional air separation plants are affected by the grid utilization and correspondingly strongly varying electricity tariffs.

It is known, for example, to produce as large an amount of liquid air products (eg liquid oxygen: LOX, liquid nitrogen: LIN, liquid argon: LAR or liquid air: LAIR) in an air separation plant at low-flow or excess-flow times and to store them in storage containers. These liquid air products can be fed back to the air separation plant during high current or peak current times. Corresponding methods and devices are for example in the WO 2005/064252 A1 described.

The possible degree of flexibilization depends on the liquefaction capacity of the air separation plant. The greater the available liquefaction capacity, the more favorable flow can be stored in the form of liquid air products. However, in particular, air separation plants for supplying power generation processes and apparatus have low liquefaction capacity as they are designed for the production of large quantities of gaseous oxygen and nitrogen products taken from the air separation plant at ambient temperature. The refrigeration requirement of such plants is relatively small, so that they are not designed to provide a sufficient amount of cold for the exclusive provision of larger amounts of liquid air products.

Therefore, a separate liquefaction plant (LIN, LOX or LAIR condenser) will be installed in appropriate plants and switched on during the liquefaction phase. Furthermore, flexibilization can also be achieved by designing the refrigeration capacity (and thus the liquefaction capacity) of the process or installation to be higher than that required for the actually required quantities of gaseous oxygen and nitrogen products.

The limits of flexibility are initially limited by the load ranges of the installed machines, eg booster compressors, turbines and heat exchangers. These can, for example, be extended to a certain extent by multiple execution (eg two parallel-connected turbines or parallel-connected booster compressors). However, one reaches the limits at the latest when the interpretation the heat exchanger used is no longer sufficient. Further flexibility is then no longer possible.

In this case, as mentioned, the use of the separate liquefaction plant is required, but their provision is associated with high investment costs. In addition, this plant will be operational only during the liquefaction phase, which lasts only a few hours per day. In the meantime, their components (heat exchangers and turbines) will heat up, either partially or completely, and will have to be cold-started again before commissioning. This means additional energy consumption.

The object of the present invention is therefore to increase the flexibility of corresponding processes or air separation plants, in particular those which supply processes and devices for generating electrical energy.

Disclosure of the invention

This object is achieved by a method for producing at least one air product, an air separation plant and a method and an apparatus for generating electrical energy with the features of the independent claims. Preferred embodiments are the subject of the dependent claims and the following description.

Before explaining the advantages obtainable in the context of the present invention, some terms used in this application will be explained.

An "air separation plant" is charged with possibly dried and purified air, which is provided by means of a "main air compressor" in the form of at least one compressed air flow. As mentioned, an air separation plant has a distillation column system for separating the air into its physical components, in particular into nitrogen and oxygen. For this purpose, the air is cooled to near its dew point and introduced into the distillation column system, as explained above. In contrast, a pure "air liquefaction plant" does not include a distillation column system. Incidentally, the structure of an air liquefaction plant may be that of an air separation plant with the delivery of an air liquefaction product correspond. Of course, liquid air can be generated as a by-product in an air separation plant.

A "liquid air product" is any product which can be prepared, at least by compressing, cooling and then releasing air in the form of a cryogenic liquid. In particular, as mentioned above, these may be liquid oxygen (LOX), liquid nitrogen (LIN), liquid argon (LAR) or liquid air (LAIR). The terms "liquid oxygen" and "liquid nitrogen" in each case also designate cryogenic liquids which have oxygen or nitrogen in an amount which is above that of atmospheric air. It does not necessarily have to be pure liquids with high contents of oxygen or nitrogen. Liquid nitrogen is thus understood to mean either pure or substantially pure nitrogen, as well as a mixture of liquefied air gases whose nitrogen content is higher than that of the atmospheric air. For example, it has a nitrogen content of at least 90, preferably at least 99 mole percent.

A "cryogenic" liquid, or a corresponding fluid, liquid air product, stream, etc., is understood to mean a liquid medium whose boiling point is significantly below the respective ambient temperature and, for example, 200 K or less, in particular 220 K or less. Examples of cryogenic media are liquid air, liquid oxygen and liquid nitrogen in the above sense.

A "heat exchanger" serves to transfer heat indirectly between at least two countercurrent streams, for example, a warm compressed air stream and one or more cold streams or a cryogenic liquid air product and one or more hot streams. A heat exchanger may be formed from a single or multiple heat exchanger sections connected in parallel and / or in series, for example from one or more plate heat exchanger blocks. A heat exchanger, for example, the "main heat exchanger" used in an air separation plant, which is characterized in that the main part of the streams to be cooled or heated to be cooled or heated by him, has "passages" as separate fluid channels with heat exchange surfaces are formed.

A "compressor" is a device designed to compress at least one gaseous stream from at least one inlet pressure at which it is fed to the compressor to at least one final pressure at which it is taken from the compressor system. A compressor forms a structural unit, which, however, can have a plurality of "compressor stages" in the form of known piston, screw and / or paddle wheel or turbine arrangements (ie axial or radial compressor stages). This also applies to a "main air compressor" of an air separation plant, which is characterized by the fact that all or predominantly the amount of air that is fed into the air separation plant is compressed by it. In particular, these compressor stages are driven by means of a common drive, for example via a common shaft. Several compressors, e.g. a main and a post-compressor of an air separation plant, may be coupled together. A "secondary compressor" is designed to further increase the pressure of an already pressurized stream.

An "expansion turbine", which can be coupled via a common shaft with further expansion turbines or energy converters such as oil brakes, generators or compressors, is set up for relaxing a gaseous or at least partially liquid stream. In particular, expansion turbines may be designed for use in the present invention as a turboexpander. If a compressor is driven with one or more expansion turbines and this, however, operated without externally, for example by means of an electric motor, supplied energy, the term "turbine-driven" compressor is used here. Arrangements of turbine-driven compressors and expansion turbines are also referred to as "booster turbines".

In the context of the present application, a "tank system" is understood to mean an arrangement having at least one cryogenic storage tank set up to store a liquid air product. A corresponding tank system has insulation means.

The present application uses the terms "pressure level" and "temperature level" to characterize pressures and temperatures, thereby indicating that corresponding pressures and temperatures in a given plant are not in the form of exact pressure or temperature values have to be used to realize the inventive concept. However, such pressures and temperatures typically range in certain ranges that are, for example, ± 1%, 5%, 10%, 20% or even 50% about an average. Corresponding pressure levels and temperature levels can be in disjoint areas or in areas that overlap one another. In particular, for example, pressure levels include unavoidable or expected pressure drops, for example, due to cooling effects. The same applies to temperature levels. The pressure levels indicated here in bar are absolute pressures.

Liquid air products or corresponding liquid streams can be converted by heating in a gaseous or in a supercritical state. A regular phase transition by evaporation occurs when heating occurs at subcritical pressure. However, if liquid air products are heated at a pressure which is above the critical pressure, no phase transition in the true sense occurs when heating above the critical temperature, but a transition from the liquid to the supercritical state. If the term "evaporation" is used in the context of this application, this also includes the conversion from the liquid to the supercritical state.

Advantages of the invention

The invention is based on a method for producing at least one air product using an air separation plant comprising a main air compressor, a main heat exchanger and a distillation column system. At least a first compressed air flow is provided at a first pressure level by means of the main air compressor, and a first partial flow of the first compressed air flow is supplied at the first pressure level to a first passage of the main heat exchanger.

According to the invention, it has been found that a method offers particular advantages, in which a second partial flow of the first compressed air flow in a first operating mode at the first pressure level and in a second operating mode at a second pressure level that is higher than the first pressure level, a second passage of Main heat exchanger is supplied, wherein the second partial flow of the first compressed air flow in the second operating mode, at least by means of a turbine-driven booster to the second pressure level is increased and relaxed downstream of the main heat exchanger in an expansion turbine, which is used to drive the turbine-driven booster.

The "first operating mode" corresponds to a regular operation of a corresponding air separation plant, i. an operation in which predominantly or exclusively gaseous air products are made available, for example to an oxyfuel or an IGCC process. The first mode of operation may also include feeding and further separating air products previously stored in a tank system into the used distillation column system. The first operating mode is distinguished by the fact that during this no or at least no appreciable amounts of liquid air products are formed and stored in a corresponding tank system. A corresponding air separation plant is operated in such a first operating mode with regard to the highest possible or required production of gaseous air products. The total amount of air provided by the main air compressor is here typically fed to the distillation column system, i.d.R. no "excess" of air is compressed and used only or primarily to provide relaxation cooling.

In contrast, the "second mode of operation" corresponds to a predominant or exclusive liquefaction operation of a corresponding air separation plant which produces less or no gaseous products of air. Typically, in the second mode of operation, not all of the air provided by the main air compressor is fed into the distillation column system, but a part is depressurized and thereafter blown off in whole or in part, for example, to the atmosphere.

The invention thus provides an air separation plant in which a liquefaction plant is functionally integrated. At the same time, the main heat exchanger of the air separation plant is also used for liquefaction, which can significantly reduce costs compared to separate liquefaction plants. In addition, the main heat exchanger (especially in contrast to a separate liquefaction plant) always remains in the cold state, so that the connection of the "condenser" - or the components used for this purpose Air separation plant - can be done much faster and the above-mentioned cold running losses are reduced.

The refrigeration for the liquefaction is supplied by the aforementioned expansion turbine, which is "driven" by the main air compressor, because it relaxes a compressed air flow supplied by this. In this way, it becomes possible to use an excessively available power of the main air compressor for liquefaction in periods where less gaseous air products are produced than actually possible, so to speak in a "under load operation" (in the second operating mode). An additional booster can then be made smaller or completely eliminated.

In order to enable the integration of the condenser in the air separation plant, the heat exchanger according to the invention is specifically designed and is switched accordingly: Normally, this comprises a single passage for the air of said first compressed air flow with an inlet and an outlet nozzle. By contrast, in the method proposed according to the invention, two, three or more separate, i. separate passages provided with their own sockets.

In normal operation (the first operating mode), these passages are flowed through by "equal air", namely by the air of the first compressed air stream which is only divided into corresponding partial flows and which is supplied to it at the same pressure level. In the liquefaction operation, ie the second operating mode, the passages are switched differently: A (first) partial flow of the first compressed air flow is passed through a (first) passage at the first pressure level, ie without further pressure-influencing measures, via at least one other (second) Passage is a pressure increased (second) partial flow out. As already mentioned, the second partial flow is first of all pressure-increased to the second pressure level by means of the turbine-driven secondary compressor and expanded downstream of the main heat exchanger in an expansion turbine which is used to drive the turbine-driven secondary compressor. By a further (third) passage, a third, possibly also increased pressure partial flow of the first compressed air flow can be performed. Other passages and partial flows can be provided or provided.

The inventive design and the operation of the main heat exchanger according to the invention this can be easily adapted to the different operating modes (normal operation or liquefaction).

The integration of the external condenser into the air separation plant helps to reduce costs. Even cold running losses are significantly reduced, since the heat exchanger always remains cold, which offers energy advantages.

If different compressed air streams are supplied by a main air compressor, the method according to the invention can be used with any of these compressed air streams. The respectively affected compressed air flow is then the invention according to the invention divided into the partial streams "first" compressed air flow.

Thus, the first compressed air stream may be both a compressed air stream provided at a pressure level for feeding into a high pressure column of a known distillation column system and a compressed air stream provided at a pressure level for feeding into a medium or low pressure column. The main heat exchanger can also be divided into a plurality of heat exchanger blocks for realizing the method according to the invention.

The proposed measures according to the invention can be used in all known processes for the production of air products, regardless of how the distillation columns of Destillationssäulensystems are formed and / or interconnected, which type of turbines (so-called injection turbines, pressurized nitrogen turbines, medium pressure turbines, etc.) are used, such as the main heat exchanger is designed and how the respective upstream main compressor, precooling and adsorber systems are formed. The measures according to the invention are advantageous regardless of the particular liquid air product produced.

It is, as already partially mentioned, particularly advantageous if a third partial flow of the first compressed air flow is in the first operating mode at the first pressure level and in a second operating mode either at the first pressure level or at the second pressure level or at a third pressure level higher than the first and higher or lower than the second pressure level is supplied to a third passage of the main heat exchanger. This can be a so-called Be act throttling, which can then be relieved cold and fed into the distillation column system, such as a medium or low pressure column. However, with appropriate design and treatment of the first partial flow this can also be dispensed with.

Advantageously, in the first operating mode, the first partial flow and the second partial flow of the first compressed air flow downstream of the main heat exchanger can be combined to form a collecting stream and / or fed into the distillation column system. As a result, this corresponds to the operation of a conventional air separation plant, but corresponding partial flows are conducted in different passages of the main heat exchanger.

If a third partial flow is provided, it is further advantageous, in the first operating mode, to combine the first partial flow, the second partial flow and the third partial flow of the first compressed air flow downstream of the main heat exchanger into a collecting stream and / or feed it into the distillation column system, so that the entire air the first compressed air flow (at the first pressure level) is available for easy feed into the distillation column system.

Particularly advantageous is a method in which heated in the second mode of operation of the second partial stream of the first compressed air stream after relaxing in the expansion turbine to a first portion in the main heat exchanger and running from the air separation plant and optionally expanded to a second portion and fed into the distillation column system becomes. The corresponding proportions can be flexibly adjusted independently of a respective product quantity, so that the deliverable cooling capacity can be adapted to the requirements.

If a third partial flow of the first compressed air flow is formed, this, as mentioned, for example, as a throttle flow, fed downstream of the main heat exchanger in the distillation column system.

As also mentioned, in a corresponding method in the second operating mode, at least one liquid air product is obtained by means of the distillation column system and transferred into at least one storage tank. The first operating mode may also provide (eg, temporarily) the at least one liquid Remove air product from the at least one storage tank and feed it into the distillation column system. All operating modes and variants are decoupled from each other and flexibly adaptable to the respective needs.

As also mentioned, the "first" compressed air stream may be any compressed air stream having a corresponding pressure level employed in the process. Advantageously, therefore, a second compressed air stream is further provided at a further pressure level, which is either higher or lower than the first pressure level, wherein at least a partial stream of the second compressed air stream is fed to a further passage of the main heat exchanger.

The first pressure level can be, for example, at most 2 bar above a highest operating pressure at which the distillation column system is operated, that is, for example, correspond to a pressure of a high-pressure column used there. However, it may also be below a highest operating pressure at which the distillation column system is operated, for example, a pressure of a medium-pressure column. In both cases, the measures according to the invention can be used with the correspondingly explained advantages.

For the features and advantages of the air separation plant according to the invention, reference is also made to the advantages explained. Such an air separation plant comprises a main air compressor, a main heat exchanger and a distillation column system, the main air compressor is arranged to provide at least a first compressed air flow at a first pressure level and means are provided which are adapted to a first partial flow of the first compressed air flow at the first pressure level of a first Passage of the main heat exchanger. According to the invention, means are provided which are adapted to also supply a second partial flow of the first compressed air flow in a first operating mode at the first pressure level and in a second operating mode at a second pressure level which is higher than the first pressure level to a second passage of the main heat exchanger. wherein for increasing the second partial flow of the first compressed air flow in the second operating mode to the second pressure level is provided at least one turbine-driven secondary compressor coupled to an expansion turbine arranged therefor a relaxation of the second partial flow of the first compressed air flow to be driven downstream of the main heat exchanger.

Also to the features and advantages of the method and apparatus of the invention for generating electrical energy, reference is made to the above explanations. In particular, this may be an oxifuel or IGCC process or a corresponding device.

Brief description of the drawings

• Figur 1 eine nicht erfindungsgemäße Luftzerlegungsanlage in Form eines schematischen Anlagendiagramms,
• Figur 2 eine Luftzerlegungsanlage gemäß einer Ausführungsform der Erfindung in einem ersten Betriebsmodus in Form eines schematischen Anlagendiagramms,
• Figur 3 die Luftzerlegungsanlage gemäß Figur 2 in einem zweiten Betriebsmodus in Form eines schematischen Anlagendiagramms.
• Figur 4 eine Luftzerlegungsanlage gemäß einer Ausführungsform der Erfindung in dem ersten Betriebsmodus in Form eines schematischen Anlagendiagramms.
• Figur 5 die Luftzerlegungsanlage gemäß Figur 4 in dem zweiten Betriebsmodus in Form eines schematischen Anlagendiagramms.

The invention will be explained in more detail with reference to the accompanying drawings. In this show

• FIG. 1 a non-inventive air separation plant in the form of a schematic system diagram,
• FIG. 2 an air separation plant according to an embodiment of the invention in a first operating mode in the form of a schematic plant diagram,
• FIG. 3 the air separation plant according to FIG. 2 in a second operating mode in the form of a schematic plant diagram.
• FIG. 4 an air separation plant according to an embodiment of the invention in the first operating mode in the form of a schematic system diagram.
• FIG. 5 the air separation plant according to FIG. 4 in the second operating mode in the form of a schematic system diagram.

Comparable elements bear identical reference numerals in the figures and are not explained repeatedly for the sake of clarity.

Embodiments of the invention

In the FIGS. 1 to 5 In some cases, identical systems are presented in different operating modes, which include, among others, the position of a large number of Differentiate valves in corresponding lines, so that liquid and gaseous streams are each guided by different system components. The valves are not illustrated for clarity. Shutdown lines are crossed (-x-).

FIG. 1 shows a non-inventive air separation plant 110 in the form of a schematic system diagram. The air separation plant 110 comprises as central components a main air compressor 10, a main heat exchanger 20 and a distillation column system 30, which in the illustrated example is designed as a multi-column system with a high-pressure column 31, a medium-pressure column 32 and a low-pressure column 33. As already mentioned, however, the measures proposed according to the invention can be used in any distillation column systems 30.

The operating pressure of the high-pressure column 31 is, for example, 5.0 to 5.5 bar at the top, the operating pressure of the low-pressure column 33 is, for example, 1.3 to 1.4 bar at the top. The operating pressure of the medium-pressure column 32 is between the operating pressure of the high-pressure column 31 and the operating pressure of the low-pressure column 33.

For supplying the distillation column system 30 or the respective columns with corresponding compressed air, the main air compressor 10 is adapted to provide at least a first compressed air flow a and a second compressed air flow I. The pressure level of the first compressed air flow a is at the operating pressure of the high pressure column 31 (therefore also referred to as "high pressure air", HP AIR), the pressure level of the second compressed air flow I, however, at the operating pressure of the medium pressure column 32 (therefore also as "medium pressure air", MP AIR, called).

The provision of appropriate compressed air streams a and I is basically known and will not be explained in detail here. For example, 10 atmospheric air can be sucked through a filter in a main air compressor and compressed in several stages to said pressures. The first compressed air flow a can be taken, for example, at the end of a multi-stage compression, the second compressed air flow I at an intermediate point. The air can be cooled after compression in a direct contact cooler in direct heat exchange with cooling water. The cooling water may be supplied from an evaporative cooler and / or from an external source. The compressed and cooled air can then be cleaned in a cleaning device. The cleaning device may comprise a pair of containers filled with a suitable adsorbent material.

In the example shown, the first compressed air flow a is conducted at the said pressure level through a passage 25 of the main heat exchanger 20 and cooled there to a near dew point. Further, the designated a, cooled compressed air flow a is fed downstream of the main heat exchanger 20 to a proportion in the high-pressure column 31 and to another part in a bath evaporator or condenser 34, which is filled with an oxygen-rich liquid (see below) liquefied. From the liquefied portion, in turn, a portion is fed liquid into the medium-pressure column 32 and passed a further portion through a subcooler 35 and expanded into the low pressure column 33.

The second compressed air flow I is led to a portion through a passage 24 of the main heat exchanger 20 and cooled there to near dew point. On the other hand, another portion is passed through a heat exchanger element 44, which may also be integrated in the main heat exchanger 20, where it is used to evaporate an oxygen-rich liquid stream n (see below). The subsequently reunited fractions are fed into the medium-pressure column 32.

From the bottom of the high-pressure column 31 and the medium-pressure column 32 each oxygen-enriched liquid streams are withdrawn, passed as a stream h through the subcooler 35, and expanded into the low pressure column 33.

From the bottom of the low pressure column 33, an oxygen-rich liquid stream i is withdrawn, increased pressure by means of a pump 36, transferred via a flash valve (without designation) in a falling film evaporator or condenser 37, partially evaporated there against a nitrogen-rich stream (see below), and in an oxygen column 38 with another falling film evaporator or condenser 39 transferred. Liquid and gaseous fractions obtained from the head of the oxygen column 38 are returned as stream k to the low-pressure column 33.

From the bottom of the oxygen column 38, a liquid, oxygen-rich stream is withdrawn and transferred to the bath condenser 34. From the head of the bath condenser 34, a gaseous, oxygen-rich stream m is withdrawn, heated in the main heat exchanger 20 and used to provide a gaseous oxygen pressure product (referred to herein as GOX). From the bottom of the bath condenser 34, a liquid, oxygen-rich stream is withdrawn, from which a partial flow n liquid pressure increases, evaporated in the heat exchanger element 44 and also used to provide the gaseous oxygen pressure product. On the other hand, a partial flow o is partially supercooled in the subcooler 35 and used to provide a liquid oxygen product (referred to herein as LOX).

From the top of the high-pressure column 31, a nitrogen-rich gaseous stream p is withdrawn and liquefied in the falling-film evaporator or condenser 39. A partial flow is returned to the high-pressure column 31, a further partial flow (see link A) is passed through the subcooler 35 and then expanded into the low-pressure column 33.

From the top of the medium-pressure column 32, a nitrogen-rich gaseous stream r is withdrawn and liquefied in the falling-film evaporator or condenser 37. A partial flow is returned to the medium-pressure column 32, a further partial flow s passed through the subcooler 35 and then partially relaxed in the low pressure column 33 and partially provided in the form of a liquid nitrogen product (here referred to as LIN). Another partial flow t is heated in the main heat exchanger 20. Again, a portion can be removed from the main heat exchanger 20 at an intermediate temperature and expanded in a generator turbine 45 (so-called pressurized nitrogen turbine). The portion not relaxed in the generator turbine 45 is provided in the form of a gaseous nitrogen pressure product (here referred to as PGAN). From the top of the low pressure column 33, a residual gas flow u is subtracted.

Due to the fact that it is not possible to expand the cooling capacity that can be provided by the main heat exchanger 20, the air separation plant 110 often proves to be not sufficiently flexible, in particular for providing highly fluctuating quantities of liquid air products.

FIG. 2 shows an air separation plant according to an embodiment of the invention in a first operating mode in the form of a schematic plant diagram. The air separation plant is designated 100 in total.

The distillation column system of the air separation plant 100 is substantially similar to that of the air separation plant 110 and will not be discussed repeatedly. The FIG. 2 shows the air separation plant 100 in a first operating mode, the following FIG. 3 in a second mode of operation.

In contrast to the single passage 25 of the main heat exchanger 20 through which the entire compressed air flow a is guided in the air separation plant 110, here three passages 21, 22, 23 are provided, are guided by the respective partial flows b, c and d. In the in FIG. 2 shown first operating mode, these are subjected to no further pressure-influencing measures, but only supplied to the corresponding passages at the appropriate pressure level. Subsequently, the partial streams are combined to form a collecting stream g, which is essentially the cooled stream a of the FIG. 1 equivalent.

In the in FIG. 2 shown no significant amounts of liquid air products of the air separation plant 100 are removed, therefore, no cooling capacity is provided, which would exceed the producible in the air separation plant 110 cooling capacity.

In the in FIG. 3 On the other hand, in the second mode of operation shown, a liquefaction operation is carried out in which the partial flow c is initially passed through a turbine-driven booster 41, so that the partial flow c, after cooling in an aftercooler 43, is supplied to the passage 22 of the main heat exchanger 20 at an elevated pressure level , The partial flow c is taken from the main heat exchanger 20 at an intermediate temperature and expanded in the expansion turbine 42, which drives the additional compressor 41. After the expansion of the partial flow c, it is partially released into the low-pressure column 33 ("blown in", cf., linkage D) and partially combined with the residual flow u and heated in the main heat exchanger 20.

The partial flow d is here compressed by means of a further after-compressor 46 (with aftercooler). After cooling in the passage 23 of the main heat exchanger 20, this is expanded into the medium-pressure column 32 ("throttle flow", see link C).

The released during the individual relaxation steps cold is available for the formation of larger amounts of liquid air products (here liquid nitrogen: LIN and liquid oxygen: LOX) available.

FIG. 4 shows an air separation plant according to an embodiment of the invention in the first operating mode in the form of a schematic plant diagram. In the FIG. 4 and the following ones FIG. 5 shown air separation plant differs from that in the Figures 2 and 3 illustrated plant essentially by the configuration of the main heat exchanger 20 and the distillation column system 30, which is only partially explained here. In the distillation column system 30, inter alia, the high-pressure column 31 with the low-pressure column 33 is designed as a double column. However, other configurations are possible. Other illustrated columns of the distillation column system 30 used are not explained in detail. The compressed air flow a is divided here into further partial flows e and f.

In the in FIG. 4 If required, previously stored liquid air products, here liquid nitrogen (LIN) and liquid oxygen (LOX) in the form of the streams v and w are fed into corresponding components of the distillation column system 30 (low-pressure column 33 or bath evaporator 35), a withdrawal, for example from Liquid oxygen (LOX) does not occur. This first mode of operation is essentially the same as that of FIG. 2 ie only small amounts of liquid air products are formed. Also in the in FIG. 2 shown air separation plant 100 is a corresponding feed of liquid nitrogen (LIN) and liquid oxygen (LOX) possible. Further withdrawn streams are designated R and DCAC.

The in FIG. 5 shown second operating mode substantially corresponds to the in FIG. 3 illustrated second operating mode of the air separation plant 100th

Claims (14)

A method of producing at least one air product using an air separation plant (100) comprising a main air compressor (10), a main heat exchanger (20), and a distillation column system (30), wherein at least one first compressed air flow (a) is produced by means of the main air compressor (10) ) is provided at a first pressure level and a first partial flow (b) of the first compressed air flow (a) at the first pressure level of a first passage (21) of the main heat exchanger (20) is supplied, characterized in that further comprises a second partial flow (c) of first compressed air flow (a) in a first operating mode at the first pressure level and in a second operating mode at a second pressure level, which is higher than the first pressure level, a second passage (22) of the main heat exchanger (20) is supplied, wherein the second partial flow ( c) of the first compressed air flow (a) in the second operating mode at least by means of a turbine-driven secondary compressor s (41) is pressure-increased to the second pressure level and released downstream of the main heat exchanger (20) in an expansion turbine (42) used to drive the turbine-driven post-compressor (41). The method of claim 1, wherein a third substream (d) of the first pressurized air stream (a) in the first mode of operation at the first pressure level and in a second mode of operation either at the first pressure level or at the second pressure level or at a third pressure level higher as the first and higher or lower than the second pressure level, a third passage (23) of the main heat exchanger (20) is supplied. Method according to Claim 1 or 2, in which, in the first operating mode, the first partial flow (b) and the second partial flow (c) of the first compressed air flow (a) are combined downstream of the main heat exchanger (20) to form a collecting stream (g) and / or into the Distillation column system (30) are fed. The method of claim 2, wherein in the first mode of operation, the first partial flow (b), the second partial flow (c) and the third partial flow (d) of the first compressed air flow (a) downstream of the main heat exchanger (20) to a Collection stream (g) combined and / or fed into the distillation column system (30). Method according to one of the preceding claims, in which, in the second operating mode, the second partial flow (c) of the first compressed air flow (a) after being expanded in the expansion turbine (42) is heated to a first fraction in the main heat exchanger (20) and from the air separation plant ( 100) and optionally expanded to a second portion and fed into the distillation column system (30). Method according to one of claims 2 to 5, wherein in the second mode of operation, the third partial flow (d) of the first compressed air flow (a) is fed downstream of the main heat exchanger (20) in the distillation column system (30). Method according to one of the preceding claims, wherein in the second operating mode by means of the distillation column system (30) at least one liquid air product is recovered and transferred into at least one storage tank. The method of claim 7, wherein the first operating mode comprises a first and a second operating variant, wherein the at least one liquid air product is removed in the second operating variant from the at least one storage tank and fed to the distillation column system (30). Method according to one of the preceding claims, in which by means of the main air compressor (10) a second compressed air flow (I) is further provided at a further pressure level which is either higher or lower than the first pressure level, at least a partial flow of the second compressed air flow (I). a further passage of the main heat exchanger (20) is supplied. A method according to any one of the preceding claims, wherein the first pressure level is at most 2 bar above a highest operating pressure at which the distillation column system (30) is operated. The method of any one of claims 1 to 9, wherein the first pressure level is below a highest operating pressure at which the distillation column system (30) is operated. Air separation plant (100) comprising a main air compressor (10), a main heat exchanger (20) and a distillation column system (30), wherein the main air compressor (10) is adapted for providing at least a first compressed air flow (a) at a first pressure level and means are provided adapted to supply a first partial flow (b) of the first compressed air flow (a) at the first pressure level to a first passage (21) of the main heat exchanger (20), characterized by means adapted to further supply a second partial flow (c ) of the first compressed air flow (a) in a first operating mode at the first pressure level and in a second operating mode at a second pressure level which is higher than the first pressure level, a second passage (22) of the main heat exchanger (20) to supply, wherein for increasing second partial flow (c) of the first compressed air flow (a) in the second operating mode to the second pressure level at least a turbine-driven booster (41) is provided which is coupled to an expansion turbine (42) which is adapted to be driven by a relaxation of the second partial flow (c) of the first compressed air flow downstream of the main heat exchanger. Method for producing electrical energy, in which at least one air product is provided by means of a method according to one of claims 1 to 11, at least during the first operating mode, and is used to generate and / or convert at least one fuel. Plant adapted for carrying out a method according to claim 13, in particular for carrying out an oxifuel process and / or a combined process with integrated gasification.

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