EP3019804A2

EP3019804A2 - Method for producing at least one air product, air separation system, method and device for producing electrical energy

Info

Publication number: EP3019804A2
Application number: EP14739044.7A
Authority: EP
Inventors: Alexander Alekseev
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2013-07-11
Filing date: 2014-07-10
Publication date: 2016-05-18
Also published as: CN105378411A; WO2015003808A3; US20160370111A1; TW201518664A; CN105378411B; KR20160032160A; AU2014289591A1; WO2015003808A2

Abstract

The invention relates to a method for producing at least one air product, wherein an air separation system (100) is used which has a primary air compressor (10), a primary heat exchanger (20) and a distillation column system (30), and which comprises a first and a second operation mode, wherein, in the first operating mode, at least one liquid air product (LIN, LOX) produced in the distillation column system (30) is saved and, in the second operating mode, the at least one air product (LIN, LOX, LAIR) saved in the first operating mode and/or at least one additional liquid air product is supplied to the distillation column system (30). The method is characterized in that, in the second operating mode, at least one gaseous pressure flow (b - g) at a temperature level which lies below a hot-side temperature of the primary heat exchanger (20) is supplied to a cold compressor (45), compressed in the cold compressor (45) from a first above-atmospheric pressure level to a second above-atmospheric pressure level, and is supplied to at least one distillation column (31, 32) of the distillation column system (30) at the second above-atmospheric pressure level. The invention further relates to a corresponding air separation system (100) and to a method and to a device for producing electrical energy.

Description

description

Method for producing at least one air product, air separation plant, method and device for generating electrical energy

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.

The term "condenser-evaporator" refers to a heat exchanger in which a first condensing fluid stream undergoes indirect heat exchange with a second evaporating fluid stream. Each condenser evaporator has a

Liquefaction room and an evaporation room on that off

Condensing passages or evaporation passages exist. In the liquefaction space, the condensation (liquefaction) of the first fluid flow is performed, in the evaporation space the evaporation of the second fluid flow. Evaporation and liquefaction space are formed by groups of passages that are in heat exchange relationship with each other. Of the

Evaporation space of a condenser-evaporator may be formed as a bath evaporator, falling film evaporator or forced-flow evaporator. In the low-pressure column bottom evaporator is in the evaporation chamber a

Bottom liquid of the low pressure column at least partially evaporated. By doing

Low-pressure column intermediate evaporator is in the evaporation chamber a

Intermediate liquid of the low-pressure column at least partially evaporated. State of the art

A method of the type mentioned and a corresponding device with three columns are known from. In known processes for generating electrical energy, for example the known oxyfuel process and so-called combined gasification combined cycle (IGCC), oxygen or oxygen-enriched gas mixtures, for example for combustion or for partial oxidation, needed. To provide the oxygen or corresponding oxygen-enriched gas mixtures, processes and devices for the cryogenic separation of air can be used, as known, for example, from Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, Chapter 4 (pages 281 to 337).

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 apparatus for generating electrical energy should be designed for large load ranges and fast load changes to intercept power surges that may result from the availability or unavailability of other power feeders. Also air separation plants, which supply oxygen or appropriate gas mixtures for this, should have an in the

appropriate scope allow flexible operation. Even conventional air separation plants are affected by the grid utilization and correspondingly strongly varying electricity tariffs.

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. In particular, air separation plants for supplying power generation processes and apparatuses, however, have a low liquefaction capacity, since these are designed for the production of large quantities of gaseous oxygen and nitrogen products, the air separation plant at

Ambient temperature are taken. 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) can be installed in appropriate plants and switched on during the liquefaction phase. Flexibilization can also be achieved by designing the refrigeration capacity (and thus the liquefaction capacity) of the process or plant to be higher than the actually required amounts of gaseous oxygen and nitrogen products.

If larger amounts of liquid air products are fed into a corresponding air separation plant, significantly more cold may possibly be introduced into the air separation plant than required. This would lead without countermeasures that shift the respective temperature profiles in the heat exchangers and the

Temperature of one or more emerging from the heat exchangers currents would always lower. Above a certain limit, safe operation of the air separation plant would no longer be guaranteed. This problem can be solved by using heat generating devices, e.g. of air, steam, gas-electrically or otherwise heated heat exchangers, be addressed. However, such a solution proves to be unfavorable, especially for energy reasons.

Object of the present invention is to provide methods of the type mentioned above and corresponding devices that have a large range of variation in their energy consumption and have a comparatively low energy consumption in all the corresponding mode of operation.

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 each 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 fed with possibly dried and purified air, which by means of a "main air compressor" in the form of at least one

Compressed air flow is provided. 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" or "liquefaction plant" does not include a distillation column system. Incidentally, the structure of an air liquefaction plant may correspond to that of an air separation plant with the discharge of an air liquefaction product. 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, this may, as mentioned, to

Liquid oxygen (LOX), liquid nitrogen (LI N), 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. Under liquid nitrogen is therefore understood as pure or substantially pure nitrogen, as well as a mixture of liquefied air gases, the nitrogen content higher than that of

atmospheric air is. 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" is used for the indirect transfer of heat between at least two countercurrently flowed, for example, a warm compressed air stream and one or more cold streams or a cryogenic liquid air product and one or more warm streams. A heat exchanger may be formed from a single or a plurality of heat exchanger sections connected in parallel and / or in series, for example 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", which are as separate fluid channels with heat exchange surfaces are formed. One

corresponding heat exchanger has in operation a "warm side" and a "cold side" whose temperatures differ. A "hot side" temperature of a heat exchanger is the temperature at which the streams to be cooled are fed to the heat exchanger. If necessary, several streams to be cooled the

Heat exchangers are supplied at different temperature levels, the hot-side temperature can also refer to the average value or the lowest or highest temperature of the supplied streams to be cooled.

A "compressor" is a device that is capable of compressing at least one

gaseous stream of at least one inlet pressure at which it is supplied to the compressor, to at least one final pressure at which this

Compressor system is removed, is set up. 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. A "cold compressor" is characterized in that it can be supplied with a corresponding current at low temperature, in particular cryogenic. Of the

Cold compressor is set up according to the prior art. An "expansion turbine" that has a common shaft with more

Expansion turbines or energy converters such as oil brakes, generators or compressors can be coupled, is set up for relaxation of a gaseous or at least partially liquid stream. In particular, you can

Expansion turbines for use in the present invention be designed 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". Under one

"Pressure nitrogen turbine" or "PGAN turbine" is referred to in the context of this application, an expansion turbine, by means of which a generated in the air separation plant and a distillation column system removed nitrogen-rich

Pressure is released. The relaxed pressure stream can then be heated, for example in the main heat exchanger and blown off to the environment. A relaxation turbine called "medium pressure turbine" becomes specific in the art

Used in connection with three-column systems, which include a high-pressure column, a medium-pressure column and a low-pressure column. A medium-pressure turbine relaxes a compressed by a main air compressor and possibly in one

After-compressor after-compressed compressed air stream after cooling in the

Main heat exchanger in the medium-pressure column. By an "injection turbine", however, is a compressed by a main air compressor and possibly in one

Post-compressor after-compressed compressed air stream after cooling in the

Main heat exchanger in the low pressure column of the three or a two-column system relaxed. By contrast, a stream which has been relaxed into the high-pressure column by means of an expansion valve is referred to as a "throttle flow". This one will be on first

Compressed pressure level above the operating pressure of the high pressure column,

for example by means of a post-compressor in or downstream of the main air compressor and / or by means of a turbine-driven compressor.

Under a "tank system" is in the context of the present application a

Arrangement understood with at least one set up for storing a liquid air product cryogenic storage tank. A corresponding

Tank system has isolation means. The present application is used for the characterization of pressures and

Temperatures the terms "pressure level" and "temperature level", which is to express that appropriate pressures and temperatures must not be used in the form of exact pressure or temperature values in order 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 each other. In particular, for example, include

Pressure levels unavoidable or expected pressure losses, for example due to cooling effects, a. 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. The method comprises, as already mentioned, a first and a second operating mode, wherein in the first operating mode at least one in the

Stored in the second operating mode, the at least one stored in the first operating mode and / or at least one further, at least not generated in the second operating mode, and / or externally supplied and / or otherwise intermediately stored liquid air product (eg liquid air, liquid nitrogen or liquid oxygen) is fed into the distillation column system.

According to the invention it is provided that in the second operating mode at least one gaseous pressure stream at a temperature level below a

Hot side temperature of the main heat exchanger is supplied to a cold compressor, in the cold compressor of a first superatmospheric

Pressure level is compressed to a second superatmospheric pressure level, and at the second superatmospheric pressure level in at least one

Distillation column of the distillation column system is fed. These

Distillation column is operated at an operating pressure, the second

corresponds to superatmospheric pressure level. This method offers considerable advantages over the prior art: As already mentioned, feeding a comparatively small amount of cryogenic liquids or liquid air products into the cold box is one

Air separation plant often readily possible because due to the inevitable heat input through the insulation and losses in the (main) heat exchanger (hot-side temperature difference) always a certain amount of cold is needed. This amount of cold is usually supplied by a used expansion turbine.

If the refrigeration demand is covered by the previously described feed, the

Relaxation machine be switched off. This allows a corresponding saving of drive power at the main air compressor and / or a downstream compressor, if a so-called medium-pressure turbine is used, is relaxed in the additional compressed air. The same applies if the corresponding method is implemented on the basis of a so-called injection turbine, by means of which air is released into the low-pressure column of the distillation column system used. If a so-called pressurized nitrogen or PGAN turbine is used, as shown in the figures shown in the context of this application, the leads

Shutting down the turbine means that a large usable amount of pressurized nitrogen is available, out of which the energy used for compression

can be recovered. For this purpose, an external expansion machine can be used, which is supplied to the corresponding pressure stream after heating in an upstream heater and the pressure flow to the for the respective application required pressure (eg for use as a regeneration) relaxed.

If, however, more cold is introduced into the coldbox over a longer period of time than is required with the feed of the cryogenic liquids or of the liquid air products, this can lead to the temperature profiles being used in the cold box

Heat exchangers unfavorably change ("warp"), causing the

Temperature of one or more emerging from the heat exchanger flows is always lower. Above a certain limit, a safe or default mode of operation of the air separation plant is no longer guaranteed. Another

Infeed is then no longer possible, unless the heat input into the coldbox is increased by an additional heat source. For these purposes, as mentioned, any known heat generating device, e.g. an air, steam, gas electrically or otherwise heated heat exchanger can be used.

In this context, however, the use of cold compressors (that is, as explained above, compressors having an intake temperature lower than the ambient temperature) has proven to be particularly advantageous since not only does this introduce heat into the system, but it also influences the overall process by deliberately compressing certain material flows and can be improved. A corresponding method is illustrated in FIGS. 1 and 2 explained below. Here is (in a "second" mode of operation, with the supply of appropriate Tiefkalter

Liquids or liquid air products is performed) compressed after the shutdown of a corresponding expansion turbine (eg a pressure nitrogen turbine, as shown in the figures, but also, for example, a Einblaseturbine) available amount of pressurized nitrogen in the cold compressor, then warmed in a preheater and in a relaxed relaxation turbine. However, the use of an external expansion turbine with upstream preheater is not satisfactory in all cases, since such hardware components are extremely expensive and must be operated with considerable energy. Thus, for example, a separate (medium-pressure) steam system is typically provided for operating a corresponding preheater. The associated losses are high. A method or a system without such devices is therefore particularly desirable and advantageous in terms of cost reduction and energy saving. The use of cold compressors in air separation plants per se is known. Thus, US Pat. No. 7,272,954 B2 uses a cold compressor for compressing a throttle flow. However, this use is the purpose of the one described here

Process or a corresponding investment diametrically opposite: a

Throttling current is, as explained, for this reason compacted in order to subsequently make a corresponding relaxation in the high-pressure column for the production of additional cold. The inductor current is here so on a higher

compressed superatmospheric pressure level, but not in this in the

High-pressure column fed, but previously relaxed again. In the context of the present invention, furthermore, the first superatmospheric pressure level is below the operating pressure of the high-pressure column.

In the already mentioned "first operating mode" of a corresponding air separation plant gaseous air products are not necessarily provided, for example to an oxyfuel or an IGCC process. The first mode of operation may also include taking out liquid air products from a corresponding installation and transferring them into storage tanks provided for this purpose (during the aforementioned low-flow or excess-time periods). The first

Operating mode is characterized mainly by the fact that additional cold air is generated in the air separation plant, for example by means of a pressurized nitrogen, a Einblase- and / or a medium-pressure turbine. In the first operating mode, at most small quantities of air products previously stored in a tank system are fed into the distillation column system used and, if necessary, further separated, so that the mentioned negative effects of excessive

Do not adjust cold entry.

On the other hand, in the mentioned "second mode of operation" i.d.R. no additional cold generated by means of a pressure nitrogen, a Einblase- and / or a medium-pressure turbine, because in this previously stored in storage tanks air products are fed into the distillation column system used and, if necessary, further separated. These air products can also by means of additional devices or

Plants are stored or provided in the storage tanks, for example by means of a separate condenser. In the second operating mode comes the Cold compressor used to ensure a heat input and simultaneously make a compression of a corresponding pressure flow.

The invention thus provides an air separation plant, which enables cost-effective means a particularly advantageous operation even when larger amounts, for example, previously stored in storage tanks, liquid air products. This can be significantly reduced in particular compared to air separation plants with heated heat exchangers, but also compared to systems with cold compressors and external expansion turbines, the cost.

Of course, the above-described first

Operation mode may be included, in which the at least one and / or at least one further gaseous pressure stream in a expansion turbine can be relaxed cold. The process can be switched as needed between the two operating modes.

The method can advantageously be used when a

Distillation column system is used, which is a high pressure column and a

Low pressure column includes, the high pressure column at a higher

Operating pressure is operated as the low pressure column. such

Distillation column systems (for example, double column systems or systems with separate high and low pressure columns) are generally known in the art. The process is thus suitable for retrofitting a large number of existing air separation plants with corresponding distillation column systems.

In such distillation column systems, the first pressure level corresponds to the operating pressure of the low-pressure column and / or the second pressure level to

Operating pressure of the high pressure column. The invention allows a corresponding pressure increase and transfer of a pressure flow at the same time dosed

Cold entry into the distillation column system.

Particular advantages and an even more flexible process result when a distillation column system is used, which additionally comprises a medium-pressure column which is operated at an operating pressure which is between the

Operating pressures of the high pressure column and the low pressure column is. Correspondingly, here the first pressure level correspond to the operating pressure of the low-pressure column and the second pressure level correspond to the operating pressure of the medium-pressure column or the high-pressure column. Alternatively, the first pressure level may correspond to the operating pressure of the medium-pressure column and the second pressure level may correspond to the operating pressure of the high-pressure column.

In all cases, the at least one gaseous pressure stream may be formed from at least a portion of a stream which is one at the first pressure level

Operating pressure operated distillation column of the distillation column system is removed, ie a low-pressure column or, if present, optionally also a medium-pressure column. After compression in the cold compressor, the at least one gaseous pressure stream can then at least partially be transferred to a distillation column at a higher pressure level (in the case of removal from the low-pressure column, therefore

Medium pressure column or the high pressure column, when removed from a medium pressure column, the high pressure column) are fed.

Alternatively, however, the at least one gaseous pressure stream may also be formed from at least part of a stream which is conveyed by means of the

Provided and cooled by means of the main heat exchanger, so for example, a "medium-pressure flow", which is intended in part for feeding into a medium-pressure column of the distillation column system and is present at a corresponding pressure. Such, then compressed in the cold compressor gaseous pressure stream, can then be fed to the operated at a corresponding pressure level distillation column.

Before being fed into the respective distillation column, the at least one gaseous pressure stream at the second pressure level can also be combined with at least one further stream. If such a second pressure level corresponds, for example, to the operating pressure of the high-pressure column, a correspondingly compressed gaseous pressure stream can therefore be combined with a corresponding compressed-air flow which is provided by a main air compressor at this second pressure level and cooled in the main heat exchanger. If the compressed gaseous pressure stream is not yet at a desired temperature, the at least one gaseous pressure stream after compression in the

Cold compressor be cooled at least partially in the main heat exchanger. This is also an advantageous measure to counteract an unfavorable change in temperature profiles of the main heat exchanger caused by the feed of liquid air products by targeted introduction of temperature.

In this case, as needed, and e.g. shown in Figures 9 and 10, a feed at any point in the heat exchanger, depending on where a particularly favorable cooling and / or influencing the temperature profiles can be effected. Thus, the at least one gaseous pressure stream after compression in the cold compressor for cooling the main heat exchanger on the hot side or at a further temperature level below a hot side

Temperature of the main heat exchanger is supplied.

The process also offers advantages when part of the cold compressor

heated compressed gas stream in the main heat exchanger and / or at least partially discharged from the air separation plant. A corresponding stream can be used, for example, as a regeneration gas in a cleaning device with adsorber containers and is available for this purpose at a particularly favorable pressure and temperature level.

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 has a main air compressor, a main heat exchanger and a

A distillation column system and is arranged for operation in the illustrated first and the explained second operating mode, wherein means are provided which are adapted to at least one in the first operating mode in the

Store in the second operating mode, the at least one stored in the first operating mode and / or at least one further liquid air product in the distillation column system. Corresponding means, for example, manual or

Control technology trained switching means include. The air separation plant has a cold compressor. Furthermore, means are provided which are set up in the second operating mode for the at least one gaseous pressure stream a temperature level that is below a hot side temperature of the

Main heat exchanger is to supply the cold compressor to compress in the cold compressor from a first superatmospheric pressure level to a second superatmospheric pressure level, and then at the second pressure level at least partially feed into at least one distillation column of the distillation column system.

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 oxyfuel or IGCC process or a corresponding device.

Brief Description of the Drawings The invention will be further described with reference to the accompanying drawings. In this show

1 shows a non-inventive air separation plant in a first

Operating mode in the form of a schematic system diagram,

FIG. 2 shows the air separation plant according to FIG. 1 in a second operating mode in the form of a schematic plant diagram;

3 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram, FIG.

4 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram; FIG. 5 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram;

6 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram, FIG. 7 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram, FIG.

8 shows an air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic plant diagram, FIG.

Figure 9 shows a way to arrange a cold compressor in one

Air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic partial diagram, and

Figure 10 shows a way to arrange a cold compressor in one

Air separation plant according to an embodiment of the invention in the second operating mode in the form of a schematic partial diagram, embodiments of the invention

Comparable elements bear identical reference numerals in the figures and are not explained repeatedly for the sake of clarity. In FIGS. 1 to 10 partially identical systems and components of such systems are shown in different operating modes, which differ, inter alia, in the position of a multiplicity of valves in corresponding lines, so that liquid and gaseous streams are guided through different system components. The valves are not illustrated. Shutdown lines are crossed (-x-).

1 shows a non-inventive air separation plant 1 10 in the form of a schematic system diagram. The air separation plant 10 is shown in Figure 1 in a first mode of operation in which it does not receive appreciable quantities of liquid air products from "external sources", e.g. from a storage tank or an air liquefaction plant. The illustrated first mode of operation, for example, for the production of liquid air products in low-cost or

Current excess times used, which are stored in corresponding storage tanks and ready for the shown in FIG. 2 second operating mode for feeding into the air separation plant 1 10. Another operating mode may also include the exclusive or predominant provision of gaseous air products.

The air separation plant 110 comprises as central components a main air compressor 10, a skin heat exchanger 20 and a distillation column system 30, which in the illustrated example is a multi-column system with a high-pressure column 31, a medium-pressure column 32 and a low-pressure column, the low-pressure column having a first section 38 and a second portion 33. These two sections are connected via a gas line k, which has no pressure-changing measures and thus form a uniform distillation space, which is not to be distinguished from a one-piece low-pressure column in terms of separation efficiency, pressure and temperatures.

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", HPAIR), the

Pressure level of the second compressed air stream I, however, at the operating pressure of the medium-pressure column 32 (therefore also referred to as "medium-pressure air", MPAIR).

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 in a cleaning device getting cleaned. The cleaning device may comprise a pair of containers filled with a suitable adsorbent material. For regeneration of the cleaning device, a nitrogen-rich regeneration gas, here in the form of the stream v explained below, is used

In the example shown, the first compressed air flow a on said

Pressure level passed through a passage 21 of the main heat exchanger 20 and cooled there to near dew point. The cooled compressed air stream, which is also denoted by a, is fed into the high-pressure column 31 downstream of the main heat exchanger 20 and liquefied to a further part in a bath evaporator or condenser 34 which is filled with an oxygen-rich liquid (see below). 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 to a proportion 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, as stream h through the

Subcooler 35 out, and relaxed in the low pressure column 33.

From the bottom of the low-pressure column, 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 low-pressure column intermediate evaporator 37, partially evaporated there against a nitrogen-rich stream r (see below), and in the first section 38 of the low pressure column, in the swamp a

Low-pressure column bottom evaporator 39 is arranged. In the example, the two condenser evaporators, the low-pressure column intermediate evaporator 37 and the low-pressure column bottom evaporator 39, designed as a falling film evaporator. Liquid and gaseous fractions obtained from the head of the oxygen column 38 are referred to as Stream k partially returned to the low pressure column 33. Another part of the from the evaporation chamber of the low-pressure column intermediate evaporator 37th

effluent is applied as reflux liquid to the first section 38 of the low-pressure column.

From the bottom of the low-pressure column 38, a liquid, oxygen-rich stream is withdrawn and transferred to the secondary condenser 34, which is designed as a condenser-evaporator with liquid bath (bath evaporator). From the top of the secondary condenser 34, a gaseous, oxygen-rich stream m is withdrawn, heated in the main heat exchanger 20 and to provide a gaseous

Oxygen printed product (referred to herein as GOX). From the bottom of the secondary 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. A partial flow o, however, is partially subcooled in the subcooler 35 and to

Providing a liquid, oxygen-rich air product (referred to herein as LOX). The liquid air product can be transferred to and stored in a suitable storage tank 61. 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 into the

Low pressure column 33 relaxes.

From the top of the medium-pressure column 32, a nitrogen-rich gaseous stream r is withdrawn and liquefied to a part 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 into the

Low pressure column 33 relaxed and partially provided in the form of a liquid, nitrogen-rich air product (here referred to as LIN). This can also be stored in a suitable storage tank 62.

Another (larger) partial flow t of the flow r is in the illustrated first operating mode, bypassing a cold compressor 45 in the main heat exchanger 20 heated. Again, a portion thereof, illustrated here as stream u, can be taken from the main heat exchanger 20 at an intermediate temperature and then cold-expanded in a "cold" expansion turbine 46 (so-called pressurized nitrogen turbine), which may be coupled to a generator, for example. The portion not expanded in the expansion turbine 45 is provided in the form of a gaseous nitrogen-rich air product (here designated MPGAN). After the expansion in the expansion turbine 45, the current u is again conducted from the cold end to the warm end through the main heat exchanger 20 and split warm side of the main heat exchanger 20 in the partial streams v and w. The partial flow v is used as regeneration gas (REGGAS) in the main air compressor 10 or a cleaning device associated therewith (see above). By contrast, the partial flow w is heated by means of a heat exchanger 51 operated with a hot water flow and subsequently expanded in a further expansion turbine 52, which can likewise be coupled to a generator.

From the top of the low-pressure column 33, a nitrogen-rich stream y is withdrawn, heated in the main heat exchanger 20 and discharged from the air separation plant 1 10. As already explained, the use of the expansion turbine 46 serves to ensure that it is always required due to an unavoidable heat incidence through the insulation and losses in the main heat exchanger (hot-side temperature difference)

To deliver the amount of cold. If this cold, as already covered in the second operating mode of the air separation plant 1 10, shown in Figure 2, by fed liquid air products, the expansion turbine 46 can be turned off. This results in the example shown that a large usable amount of a corresponding nitrogen-rich air product is available under pressure, from which energy can be recovered. In other configurations, for example, where a "directly" provided by the main air compressor and cooled in the main heat exchanger pressure stream in a corresponding

Relaxation turbine (analogous to the expansion turbine 46) is relaxed, however, can reduce the drive power in the main air compressor 10 done.

FIG. 2 shows a corresponding second operating mode of the air separation plant 110. In this one hand, an oxygen-rich liquid air product (LOX) transferred from the storage tank 61 in the bath evaporator or condenser 34 (see link B) and on the other hand, a liquid air product (for example, liquefied air from an external condenser, here referred to as LAIR), fed from a further storage tank 63 in the low pressure column 33. As a result, the refrigeration demand of the air separation plant 1 10 is already covered by demand, the

Relaxation turbine 46 are turned off. Depending on the removal amount of the gaseous nitrogen-rich air product (MPGAN), which can be adjusted by a non-designated valve, thus a large usable amount of a corresponding nitrogen-rich air product (also referred to herein as stream x) is available under pressure, resulting in energy in the expansion turbine 52 or whose generator can be recovered. However, the air must be preheated. However, the use of a corresponding preheating device is expensive. The cold compressor 45 is also in operation in the second operating mode. As also explained, with the liquid air products (in this case LOX and LAIR) more cold is introduced into the cold box of the air separation plant 10 than required, which would lead to the respective temperature profiles in the heat exchangers "warping" and the temperature of one or more from the heat exchangers emerging streams would always colder and colder. Above a certain limit, safe operation of the air separation plant would no longer be guaranteed. This problem is in the air separation plant 1 10 by the operation of the cold compressor 45 as

Heat source dissolved. By the cold compressor 45, however, not only heat can be introduced into the system but affect the overall process by targeted compression of certain streams (here stream t) and improve what with other heat-generating devices, such as air, steam, gas electric or otherwise heated heat exchangers, would not be possible. The pressure increase caused by the cold compressor 45 can be utilized in the expansion turbine 52. A particular advantage over the air separation plant according to the invention not shown in FIG. 10 results from the air separation plant 100 according to the invention shown and described below, in which the cold compressor 45 is used as a so-called feed compressor and integrated into the distillation column system 30. In other words, in the second mode of operation, at least one gaseous pressure stream (see subsequent streams b through g) will be on one Temperature level, which is below a hot-side temperature of the main heat exchanger 20, the cold compressor 45 supplied in the cold compressor 45 from a first superatmospheric pressure level to a second

compressed superatmospheric pressure level and on the second

superatmospheric pressure level in at least one distillation column 31, 32 of the distillation column system 30 fed. In other words, in the

Cold Compressor 45, for example, a corresponding gaseous pressure flow (eg air from the main air compressor 10 in the form of the flow e explained below or a nitrogen-rich, gaseous pressure stream from one of the distillation columns in the form of the below-explained streams b to d, f and g) of a pressure level, used for a low pressure or medium pressure column 32 or 33, or more generally for a lower pressure column operating pressure, to a pressure level used for a medium pressure or high pressure column 31 or 32, more generally a higher pressure column than operating pressure , condensed. After a corresponding cooling in the main heat exchanger 20 (if necessary), the compressed stream is fed into the corresponding distillation column 31, 32 at a suitable point.

In particular, for processes in which, as in the present case, two pressure flows a and I are provided at different pressure levels by a main compressor 10, this leads to the fact that the rectification is improved. In three-pillar systems, the proportion of the air which is to be introduced into the high-pressure column 31 and compressed prior to high pressure, lower, whereas the proportion of air which is to be introduced into the medium-pressure column and must be compressed to medium pressure before, becomes higher. As a result, the total energy consumption becomes one

corresponding air separation plant 100 significantly lower. The cold compressor 45 is advantageously switched so that the connections (nozzle) of the then released expansion machine 46 are used. This considerably reduces the apparatus and circuit complexity. Figure 3 shows a corresponding air separation plant 100 according to a

Embodiment of the invention in the second mode of operation. The first

Operation mode is not shown again, but basically corresponds to that in Figure 1: In the first mode of operation, a corresponding current is passed through the expansion turbine 46, the cold compressor 45 is bypassed. In the illustrated second operating mode, as in FIG. 2, on the one hand oxygen-rich liquid air product (LOX) from the storage tank 61 in the bath evaporator or condenser 34 transferred (see link B) and on the other hand, a liquid air product (for example, liquefied air from an external

Condenser, here referred to as LAIR), fed from a further storage tank 63 in the low-pressure column 33.

Here, the cold compressor 45 is charged with a partial stream b of the nitrogen-rich stream y withdrawn from the low-pressure column 33, which is thus present at the above-mentioned superatmospheric pressure level at the top of the low-pressure column 33, for example 1, 3 to 1, 4 bar. In the cold compressor 45, this partial flow b is compressed from said ("first") superatmospheric pressure level to a higher ("second") superatmospheric pressure level, which here corresponds to the operating pressure of the medium-pressure column 32. The partial flow b compressed as explained is then supplied to a passage 25 of the main heat exchanger 20 at an intermediate temperature and cooled accordingly. After cooling, the current b in the top of the medium-pressure column 32 is abandoned. Further partial flows j (MPGAN) and z (partially used as regeneration gas, REGGAS, possibly only in the first operating mode) can also be discharged from the air separation plant if required. The arrangement of the heat exchanger 51 and the expansion turbine 52 is not used.

FIG. 4 shows a further air separation plant according to an embodiment of the invention in the second operating mode. The cold compressor 45 is also charged here with a partial flow of withdrawn from the low-pressure column 33 nitrogen-rich stream y, which is denoted by c and at the above-mentioned superatmospheric pressure level at the top of the low-pressure column 33, for example 1, 3 to 1, 4 bar, is present , In the cold compressor 45, this partial flow c is changed from the above-mentioned ("first") superatmospheric pressure level to a higher ("second") superatmospheric pressure level, but here the operating pressure of the

High pressure column 31 corresponds, compressed. The partial flow c as described is then supplied to a passage 27 of the main heat exchanger 20 at an intermediate temperature and cooled accordingly. After cooling, the current c in the top of the high pressure column 31 is abandoned. Further streams j (MPGAN) and z (partly used as regeneration gas, REGGAS, possibly only in the first

Operating mode) as well as a nitrogen-rich high-pressure stream (HPGAN) can also be discharged from the air separation plant if required. FIG. 5 shows a further air separation plant according to an embodiment of the invention in the second operating mode. The cold compressor 45 is charged here with a stream d, which is taken from the head of the medium-pressure column 32 and therefore at the aforementioned superatmospheric pressure level at the top of the

Medium pressure column 32 and at its temperature level is present. In the cold compressor 45, this partial flow d will be superatmospheric to that ("first")

Pressure level to a higher ("second") superatmospheric pressure level, which in turn corresponds here to the operating pressure of the high pressure column 31, compressed. The partial flow d compressed as explained is then supplied to a corresponding passage 27 of the main heat exchanger 20 at an intermediate temperature and cooled accordingly. After cooling, the stream d at the top of the high-pressure column 31 is abandoned. Further streams j (MPGAN) and z (partly as regeneration gas, REGGAS, used, possibly only in the first operating mode), and a high-pressure high-pressure stream (HPGAN) can also be discharged from the air separation plant if required.

FIG. 6 shows a further air separation plant according to an embodiment of the invention in the second operating mode. The cold compressor 45 is here charged with a partial flow e of the pressure flow I from the main air compressor 10, which is present at the above-mentioned superatmospheric pressure level, which corresponds to the operating pressure of the medium-pressure column 32. The partial flow e is taken from the main heat exchanger 20 at the cold end, so that its temperature level below the

hot side temperature level of the main heat exchanger 20 is located. By doing

Cold compressor 45, this partial flow e of said ("first")

superatmospheric pressure level to a higher ("second") superatmospheric pressure level, which in turn here corresponds to the operating pressure of the high pressure column 31, compressed. The partial stream e compressed as explained is then supplied to the passage 21 of the main heat exchanger 20 at an intermediate temperature and thus combined with the stream a. The current further here designated by a is cooled accordingly. After cooling, the flow a in the high-pressure column 31st

fed. Other streams j (MPGAN) and z (partially used as regeneration gas, REGGAS, possibly only in the first operating mode) can, as above, also be discharged from the air separation plant if required. FIG. 7 shows a further air separation plant according to an embodiment of the invention in the second operating mode. The cold compressor 45 is charged here with a stream f, the low pressure column 33 is removed and therefore at the above-mentioned superatmospheric pressure level of the low pressure column 33, for example, 1, 3 to 1, 4 bar, and at its temperature level. In the cold compressor 45, this partial flow f is compressed from the said ("first") superatmospheric pressure level to a higher ("second") superatmospheric pressure level, which in turn corresponds here to the operating pressure of the medium-pressure column 32. The partial flow f compressed as explained is then supplied to the passage 24 of the main heat exchanger 20 at an intermediate temperature and thus combined with the flow I. The current referred to here with I is cooled accordingly. After cooling, the current I is fed into the medium-pressure column 32. Further streams j (MPGAN) and z (partly used as regeneration gas, REGGAS, possibly only in the first

Operating mode), as explained above, if necessary, also from the

Air separation plant to be discharged.

FIG. 8 shows a further air separation plant according to an embodiment of the invention in the second operating mode. The cold compressor 45 is also charged here with a stream g, the low pressure column 33 is removed and therefore at the above-mentioned superatmospheric pressure level of the low pressure column 33, for example, 1, 3 to 1, 4 bar, and at its temperature level. By doing

Cold compressor 45, this partial flow g of the said ("first")

superatmospheric pressure level to a higher ("second") superatmospheric pressure level, which in turn corresponds to the operating pressure of the high pressure column 31, for example, 5.0 to 5.5 bar, compressed. The partial flow g compressed as explained is then supplied to the passage 21 of the main heat exchanger 20 at an intermediate temperature and thus combined with the flow a. The current further here designated by a is cooled accordingly. After cooling, the current is a u.a. in the

High pressure column 31 fed. Further streams j (MPGAN) and z (partly used as regeneration gas, REGGAS, possibly only in the first operating mode) can also be discharged from the air separation plant if required.

Figures 9 and 10 show alternative ways to arrange a

Cold compressor 45 in a schematic partial representation. The corresponding streams are not again provided with reference numerals. These possibilities can be with all Plants, which are shown in Figures 3 to 8, and be implemented in other non-illustrated embodiments of the invention.

According to FIG. 9, a stream compressed by the cold compressor 45 is supplied to the main heat exchanger 20 on the warm side. According to FIG. 10, a stream is taken from the main heat exchanger 20 at a first intermediate temperature, then compressed, and the main heat exchanger 20 at a second intermediate temperature

Intermediate temperature fed again.

Claims

claims

Process for producing at least one air product, in which a

Air separation plant (100) comprising a main air compressor (10), a main heat exchanger (20) and a distillation column system (30) comprising a high pressure column (31), a medium pressure column (32), a low pressure column (33), a low pressure column bottom evaporator (39) and one

Low pressure column intermediate evaporator (37), wherein the high pressure column (31) is operated at a higher operating pressure than the low pressure column (33), the medium pressure column (32) is operated at an operating pressure between the operating pressures of the high pressure column (31) and the low pressure column (33) and the low-pressure column bottom evaporator (39) and the

Low-pressure column intermediate evaporator (37) are designed as a condenser-evaporator,

characterized in that the method comprises a first and a second mode of operation, wherein

in the first operating mode at least one in the distillation column system

(30) generated liquid air product (LIN, LOX) stored and

in the second operating mode

- The at least one stored in the first operating mode and / or at least one further liquid air product (LIN, LOX, LAIR) is fed into the distillation column system (30) and

- At least one gaseous pressure stream (b - g) at a temperature level below a hot-side temperature of the main heat exchanger (20), a cold compressor (45) is supplied in the cold compressor (45) from a first superatmospheric pressure level to a second superatmospheric pressure level is compressed, and at least partially at the second pressure level in at least one distillation column (31, 32) of the distillation column system (30) is fed.

Method according to Claim 1, in which, in the first operating mode, the at least one and / or at least one further gaseous pressure stream (b-g) is depressurized in an expansion turbine (46).

3. The method of claim 1 or 2, wherein the oxygen-enriched stream from the bottom of the low-pressure column (33, 38) is evaporated in a secondary condenser (34) for providing a gaseous oxygen pressure product (GOX), wherein the secondary condenser (34) as capacitor Evaporator is formed. 4. The method according to any one of claims 1 to 3, wherein the first pressure level corresponds to the operating pressure of the low pressure column (33) and / or the second pressure level corresponds to the operating pressure of the high pressure column (31).

5. The method according to any one of claims 1 to 4, wherein the first pressure level, the operating pressure of the low pressure column (33) and the second pressure level the

Operating pressure of the medium-pressure column (32) or the high-pressure column (31) corresponds, or in which the first pressure level corresponds to the operating pressure of the medium-pressure column (32) and the second pressure level corresponds to the operating pressure of the high-pressure column (31).

6. The method according to any one of the preceding claims, wherein the at least one gaseous pressure stream (b - d, f, g) is formed from at least a portion of a current of a operated at the first pressure level as the operating pressure distillation column (32, 33) of the Distillation column system (30) is removed.

7. The method according to any one of claims 1 to 6, wherein the at least one

gaseous pressure stream (e) is formed from at least part of a stream which is provided by means of the main air compressor (10) and by means of

Main heat exchanger (20) is cooled.

8. The method according to any one of the preceding claims, wherein the at least one gaseous pressure stream (e) before feeding into the at least one

Distillation column (31, 32) of the distillation column system (30) at the second pressure level with at least one further stream (a) is combined.

9. The method according to any one of the preceding claims, wherein the at least one gaseous pressure stream (a - g) after the compression in the cold compressor (45) at least partially in the main heat exchanger (20) is cooled.

10. The method of claim 9, wherein the at least one gaseous

Pressure stream (a - g) after compression in the cold compressor (45) for cooling the main heat exchanger (20) hot side or on another

Temperature level below a hot side temperature of the

Main heat exchanger (20) is supplied.

1 1. The method according to any one of the preceding claims, wherein the part of the in the cold compressor (45) compressed gaseous pressure stream (a - g) in the main heat exchanger (20) heated and / or at least partially from the

Air separation plant (100) is discharged.

12. Air separation plant (100) having a main air compressor (10), a

Main heat exchanger (20) and a distillation column system (30) and is adapted for operation in a first and a second operating mode, wherein means (61-63) are provided which are adapted to in the first

Operating mode at least one in the distillation column system (30) generated liquid air product (LIN, LOX) store and in the second mode of operation, the at least one stored in the first operating mode and / or at least one further liquid air product (LIN, LOX, LAIR) in the

Feeding distillation column system (30), characterized in that the

Air separation plant (100) comprises a cold compressor, and that means are provided which, in the second operating mode, at least one gaseous pressure stream (b - g) at a temperature level which is below a hot-side temperature of the main heat exchanger (20), the cold compressor (45) to compress in the cold compressor (45) from a first superatmospheric pressure level to a second superatmospheric pressure level, and then at least partially at least at the second pressure level into at least one distillation column (31, 32) of the

Feed the distillation column system (30).

13. A method for generating electrical energy, wherein by means of a method according to any one of claims 1 to 1 1, at least during the second

Operating mode at least one air product is provided and used to generate and / or implementation of at least one fuel.

14. Plant, which is adapted to carry out a method according to claim 13, in particular for carrying out an oxyfuel process and / or a combined process with integrated gasification.