Process for the recovery of one or more air products and air cereal plants

The invention relates to a method for obtaining one or more air products and an air separation plant according to the generic terms of the independent

Claims.

State of the art

The production of air products in the liquid or gaseous state by the low-temperature decomposition of air in air separation plants is known and

for example at H.-W. Häring (Ed.), Industrial Gases Processing, Wiley-VCH,

2006, especially Section 2.2.5, "Cryogenic Rectification".

Air separation plants have rectification column systems that can 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. In addition to the

Rectification columns for obtaining nitrogen and / or oxygen in liquid and / or gaseous state, i.e. the rectification columns for nitrogen-oxygen separation, can be provided for obtaining further air components, in particular the noble gases krypton, xenon and / or argon.

The rectification columns of the rectification column systems mentioned are operated at different pressure levels. Double column systems have a so-called high pressure column (also referred to as a pressure column, medium pressure column or lower column) and a so-called low pressure column (also referred to as an upper column). The pressure level of the high pressure column is, for example, 4 to 6 bar, preferably about 5 bar. The low-pressure column is operated at a pressure level of, for example, 1.3 to 1.7 bar, preferably about 1.5 bar. The pressure levels given here and below are absolute pressures that are present at the top of the respective columns.

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

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

More conventional methods, high air pressure methods, have been used more and more recently as alternatives.

Main compressor / booster processes are characterized by the fact that only part of the total amount of feed air supplied to the rectification column system is compressed to a pressure level that is significantly above, i.e. by at least 3, 4, 5, 6, 7, 8, 9 or 10 bar the pressure level of the high pressure column. Another part of the amount of air used is only reduced to the pressure level of the high pressure column or a pressure level that is no more than 1 to 2 bar from the pressure level of the

The high-pressure column is differentiated, compressed, and fed into the high-pressure column at this lower pressure level. An example of a main compressor / booster method is shown by Häring (see above) in Figure 2.3A.

In the case of a high-air pressure process, however, the entire dem

Rectification column system total amount of feed air supplied to a

Compressed pressure level that is substantially, ie 3, 4, 5, 6, 7, 8, 9 or 10 bar above the pressure level of the high pressure column. The pressure difference can be up to 14, 16, 18 or 20 bar, for example. High-air pressure methods are known, for example, from EP 2 980 514 A1 and EP 2 963 367 A1.

From US 5,802,873 A and US 2006/0277944 A1 methods are known in which the total amount of feed air supplied to the rectification column system of an air separation plant is further compressed after compression in a main air compressor by means of boosters driven by expansion turbines. In the expansion turbines, part of the air that was previously compressed in the boosters and then partially cooled is expanded.

EP 1 055 894 A1 discloses an air separation plant in which liquefied natural gas is used as a coolant. Castle, WF, "Modern Liquid Pump Oxygen Plants: Equipment and Performance", AIChE Symposium Series, Vol. 89, No. 294, measures to remove or prevent the

The enrichment of hydrocarbons in air separation plants is discussed.

The present invention is used in particular in air separation plants with so-called internal compression (IV, Internal Compression, IC). Here, at least one product, which is provided by means of the air separation plant, is formed in that a cryogenic liquid is removed from the rectification column system, subjected to a pressure increase, and converted into the gaseous or supercritical state by heating. For example, internally compressed gaseous oxygen (GOX IV, GOX IC) or nitrogen (GAN IV, GAN IC) can be generated in this way. Internal compression offers a number of advantages over external compression, which is also possible as an alternative, and is explained, for example, in Häring (see above), Section 2.2.5.2, "Internal Compression". A system for the cryogenic separation of air,

Due to significantly lower costs and comparable efficiency, you can

High air pressure method is an advantageous alternative to the more conventional ones

Represent main / booster procedures. However, as explained in detail below, this does not apply in all cases. In particular, under certain conditions, there is a poorer energy efficiency. The present invention therefore has the task of enabling an advantageous use of a high-air pressure method, at least in some of such cases.

Disclosure of the invention

This task is accomplished through a method of obtaining one or more

Air products and an air separation plant solved with the features of the independent claims. Refinements are the subject matter of the dependent claims and the description below.

In the following, some basic principles of the present invention are first explained and the terms used to describe the invention are defined.

Under a "feed air quantity" or "feed air" for short is in the context of this

Registration of the total air supplied to the rectification column system of an air separation plant and thus all of the air supplied to the rectification column system. As already explained above, a corresponding amount of input air in a main compressor / booster process is only partially reduced to one

Compressed pressure level, which is significantly above the pressure level of the high pressure column. In contrast, in a high-air pressure process, the entire amount of air used is compressed to such a high pressure level. For the meaning of the term “clearly” in connection with main compressor / booster and high-air pressure processes, reference is made to the above explanations.

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

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

In air separation plants, multi-stage turbo compressors are used to compress the amount of air used, here called "main air compressors" or briefly as

"Main Compressor" are referred to. The mechanical structure of turbo compressors is fundamentally known to the person skilled in the art. This takes place in a turbo compressor

Compression of the medium to be compressed by means of turbine blades which are arranged on a turbine wheel or directly on a shaft. A turbo compressor forms a structural unit which, however, can have several compressor stages in a multi-stage turbo compressor. A compressor stage usually comprises a turbine wheel or a corresponding arrangement of turbine blades. All of these compressor stages can be driven by a common shaft. However, provision can also be made for the compressor stages to be driven in groups with different shafts, it also being possible for the shafts to be connected to one another via gears.

The main air compressor is also distinguished by the fact that it compresses the entire amount of air fed into the distillation column system and used for the production of air products, that is to say the entire input air.

Correspondingly, a “post-compressor” can also be provided, in which, however, only part of the amount of air compressed in the main air compressor is brought to an even higher pressure. This can also be designed as a turbo compressor. To the

Compression of partial amounts of air, further turbo compressors are typically provided, which are also referred to as boosters, compared to the

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

Furthermore, air can be expanded at several points in air separation plants, for which purpose, among other things, expansion machines in the form of turbo expanders, also referred to here as "expansion turbines", can be used. Turbo expanders can also be coupled with turbo compressors and drive them. If one or more turbo compressors are driven without externally supplied energy, ie only via one or more turbo expanders, the term “turbine booster” is also used for such an arrangement. In a turbine booster they are

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

intermediate gear) can take place.

In typical air separation plants, corresponding expansion turbines are available at different points for the generation of cold and the liquefaction of material flows. These are in particular so-called Joule-Thomson turbines, Claude turbines and Lachmann turbines. For the function and purpose of corresponding turbines, in addition to the following explanations, reference is made to the specialist literature, for example FG Kerry, Industrial Gas Handbook: Gas Separation and Purification, CRC Press, 2006, in particular Sections 2.4, "Contemporary Liquefaction Cycles", 2.6, "Theoretical Analysis of the Claude Cycle "and 3.8.1," The Lachmann Principle ".

In a Joule-Thomson turbine, a high-pressure air flow is expanded in an air separation unit. This stream is used to vaporize and warm up

internally compressed products are necessary. In most cases, this compressed air is noticeably supercooled before the expansion or is cooled relatively deeply in the supercritical state and, after expansion, is passed into the high-pressure column of a double column system. The Joule-Thomson turbine thus takes on the role of one

Expansion valve, by means of which a so-called throttle flow is expanded into the high-pressure column in conventional systems. It can also be designed as a liquid turbine, as will be explained in more detail below.

Using a Claude turbine, in the case of a double column system, cooled compressed air is expanded from a higher pressure level to the pressure level of the high pressure column and fed into it. By means of a Lachmann turbine, on the other hand, cooled compressed air is expanded to the pressure level of the low-pressure column and fed into it. A Claude turbine is also known as a medium-pressure turbine and a Lachmann turbine is also known as a low-pressure turbine. The compressed air is fed to the Claude and Lachmann turbines at a higher temperature level than Joule-Thomson turbines, so that no (significant) liquefaction occurs during expansion. The two turbines are also referred to as "gas turbines" in connection with air separation plants.

Typically, in air separation plants set up for internal compression, a Joule-Thomson turbine is used together with either a Claude turbine or a Lachmann turbine. It is also possible to use only a Claude or a Lachmann turbine without using a Joule-Thomson turbine. In all cases, the use of appropriate turbines is used to compensate for

Exergy losses and heat leaks.

Main compressor / booster processes in particular benefit from the use of a Joule-Thomson turbine (instead of the conventional expansion valve) to which the throttle flow is supplied in the liquid state at supercritical pressure and withdrawn in the liquid state at subcritical pressure. Such a turbine is also referred to as a liquid turbine (Dense Liquid Expander or Dense Fluid Expander, DLE). The energetic advantages of such a sealing fluid expander are also described in the technical literature cited at the beginning, for example Section 2.2.5.6, “Apparatus”, pages 48 and 49.

Liquid, gaseous or fluids present in a supercritical state can, in the language used here, be rich or poor in one or more

Components, where "rich" for a content of at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% and "poor" for a content of at most 25%, May represent 10%, 5%, 1%, 0.1% or 0.01% on a mole, weight or volume basis. The term "predominantly" can correspond to the definition of "rich" just made, but in particular denotes a content of more than 90%. Is here

For example, when talking about "nitrogen", it can be a clean gas, but also a gas rich in nitrogen.

The terms “pressure level” and “temperature level” are used below to characterize pressures and temperatures, which is intended to express that pressures and temperatures are not in the form of exact pressure or temperature levels. Temperature values ​​must be used to realize an inventive concept. However, such pressures and temperatures vary

typically in certain ranges which are, for example, ± 1%, 5% or 10% around a mean value. Different pressure levels and temperature levels can lie in disjoint areas or in areas that overlap one another.

In particular, pressure levels include, for example, unavoidable or expected pressure losses, for example due to cooling effects.

The same applies to temperature levels. The pressure levels specified here in bar are absolute pressures.

Advantages of the invention

In air separation processes or in corresponding systems, by means of which small amounts of liquid air products are to be provided, and in which certain internal compression pressures are required, a high-air pressure process with a so-called warm booster and optionally a so-called cold booster, both of which have a Expansion turbine driven with subsets of the feed air, an inexpensive alternative to

Main compressor / booster process.

A "warm" booster is understood to mean a booster to which air is typically at a temperature level well above 0 ° C,

for example, at ambient or cooling water temperature or, due to the heat of compression, also above it. In contrast, a "cold" booster is air at a temperature level typically below -50 ° C, which is achieved in particular by cooling the air in the main heat exchanger

Air separation plant can be achieved, fed. Specific temperature levels are discussed below. The air fed to a warm booster can in principle, but only to a comparatively small extent, in the

Main heat exchanger to be cooled.

However, the maximum pressure that can be achieved by connecting a warm and a cold booster in series may not be high enough to optimally balance the warm and cold fluid flows passed through the main heat exchanger without increasing the pressure at the main air compressor excessively or increasing the buildability limits for corresponding turbine boosters. A corresponding increase in the pressure on the main air compressor leads to a

Energy disadvantage compared to a main compressor / booster method.

Conventional main compressor / booster processes can be used to adapt relatively well to different product constellations, since both compressors used (main air compressor and booster) are "responsible" for functionally separate tasks. In principle, the main air compressor only supplies the feed air for air separation, the secondary compressor supplies energy or cold for internal compression and liquid production. By cleverly interconnecting the turbines and the

Post-compressor, in particular by an intermediate withdrawal, as well as the

Using additional inductor currents, very good energy efficiency can be achieved. However, this generally requires a large number of compressor stages, which increases the investment costs.

In a high-air pressure process, the above-mentioned tasks are performed by just one compressor. Thus, the entire feed air must be compressed to a high pressure in order to achieve a good balance between cold and warm flows in the

To achieve main heat exchanger. The required high pressure must be provided by the turbine booster or boosters and the main air compressor pressure. In some cases, especially in the case of product constellations with no or very small amounts of liquid, an efficient adjustment, as already mentioned, is difficult to achieve

realize without endangering the buildability of the turbine booster or, as mentioned, increasing the main air compressor pressure very much.

There are high-air pressure methods known in which it is provided under

Use of a cold booster, which is preceded by a warm booster, to generate a high-pressure throttle current. In this way, the buildability of the turbine booster can be significantly improved and the pressure on the main air compressor can be reduced. Since the warm booster usually has to compress a comparatively large amount of air or the proportions between the expansion turbines driving the booster and the boosters have to be set in such a way that the corresponding machines can be built, the stage pressure ratio, i.e. the pressure ratio between suction and pressure-side pressure, is on the booster, typically less than about 1.4 in conventional methods. A stage pressure ratio of up to 2 can be achieved with a cold booster.

Main compressor / booster method as not being equivalent. For example, US 2013/0255313 A1 also discloses a method with two cold boosters connected in series. However, such a method is not advantageous in all cases either.

For a fictitious product constellation (13,000 Nm 3 / h internally compressed gaseous oxygen at 15 bar), with a conventional high-air pressure circuit with a cold booster, the energy yield is only approx. 10% worse than with a main compressor / booster process (with self-boosted Lachmann Turbine, i.e. a Lachmann turbine to which an air flow is fed which has previously been compressed by a booster that is coupled to the Lachmann turbine) can be achieved. Especially in the area of ​​so-called package air separation plants (compact structural units with a production volume of up to approx. 23,000 Nm 3 / h of gaseous oxygen), those with pure gas production on one are becoming more and more common

A pressure level of approx. 30 bar is required.

The above comparison was based on the assumption that no liquid turbine is used. If a liquid turbine is used, a further one can be used, particularly in the main compressor / booster process

Increased energy efficiency can be achieved. Since the performance of a liquid turbine is generally highly dependent on the pressure, its use is generally at

conventional main compressor / booster method because of there

achievable higher pressures are always significantly more advantageous than with known ones

High air pressure method. It can therefore be assumed that the differences mentioned will increase again in this case to the disadvantage of the high-air pressure method. However, the use of a liquid turbine increases the investment costs, which is particularly disadvantageous in the case of small systems.

By means of the measures explained below, the present invention enables a significant improvement in the performance or the energy efficiency of a

High-air pressure process (compared to a main compressor / booster process), which is restricted in the manner explained by the buildability of the respective turbine / booster interconnection. This applies in particular to the previously explained case that no or only comparatively small amounts of liquid air products are to be provided. In the context of the present invention, the main advantage of a high-air pressure method (lower investment costs compared to a main compressor / booster method) is retained without impairing the energy efficiency.

The present invention solves the problems explained in that the generation of a high-pressure process air flow, which is required in particular for the evaporation of the fluid flows used to provide internal compression products, is provided by means of the turbine boosters used in a way that enables the respective stage pressure ratios to be achieved To increase turbine boosters in an advantageous manner. For this purpose, within the scope of the present invention, a method for obtaining one or more air products using an air separation plant with a first booster, a second booster, a first expansion machine and a rectification column system is proposed, which has a high-pressure column that is operated at a first pressure level, and a Low pressure column,

Pressure levels is operated, having. With regard to the first and second pressure levels, which can correspond to normal pressure levels in particular for high and low pressure columns in air separation plants, express reference is made to the explanations given at the beginning and the information below.

In the method proposed according to the invention, the entire, the

Air supplied to the rectification column system is initially compressed to a third pressure level which is at least 3 bar above the first pressure level, in particular in a main air compressor of the air separation plant. The method proposed according to the invention is therefore a typical high-air pressure method. In the context of the present invention, the third pressure level can in particular be in a range from 10 to 20 bar,

for example in a range from 11 to 14 bar.

In the context of the present invention, a first portion of the amount of air used is fed to a booster at the third pressure level and a temperature level of -140 to -70 ° C, in particular -135 to -110 ° C, which is a cold booster in the sense explained above represents. This booster is referred to below as the "first" booster. The first portion of the feed air volume is below

Use of the first booster is further compressed to a pressure level which is referred to here as the "fourth" pressure level. To cool the first portion of the

The amount of air used and for all of the further cooling and heating processes explained below, provided that these are not caused by the relaxation or

The main heat exchanger of the air separation plant is used in particular in each case.

A second portion of the feed air quantity or a subset of the first

Feed amount of air that was transferred to the fourth using the first booster

Pressure level was compressed, is a first on the third pressure level

Supplied expansion turbine, using which the first booster is driven, and in particular can be coupled to it in the manner explained above. The second portion of the feed air quantity or the partial quantity of the first feed air quantity, which was compressed to the fourth pressure level using the first booster, is calculated using this first

Relaxed expansion turbine to the first pressure level, i.e. to the pressure level at which the high-pressure column is operated. The first expansion turbine is a typical Claude turbine.

A subset of the first portion of the feed air that was compressed in the first (cold) booster is then heated in a main heat exchanger of the air separation plant in the context of the present invention and fed to a warm booster, which is referred to below as the "second" booster. The mentioned partial amount of the second portion of the input air amount is compressed by means of this second booster to an even higher pressure level, which is referred to below as the “fifth” pressure level.

According to the invention, the first portion of the input air amount is taken from the first booster at a temperature level of -120 to -60 ° C and the partial amount of the first input air amount, which is compressed to the fifth pressure level using the second booster, is before it is compressed in the second booster heated to a temperature level of -20 to 40 ° C, in particular from 20 to 30 ° C. The measures proposed with these measures consist in particular in a higher achievable stage pressure ratio, as explained in more detail elsewhere.

Furthermore, within the scope of the present invention, further air, which, as will also be explained below, is in particular a further proportion of

Feed air at the third pressure level or a further subset of the second portion of the feed air that was compressed in the first (cold) booster can act, expanded in an expansion turbine, which is referred to below as the "second" expansion turbine. Using the second

In the expansion turbine, the said additional air is expanded to the second pressure level, that is to say the pressure level at which the low-pressure column of the distillation column system used in the process is operated. So it is a typical Lachmann turbine. The second expansion turbine drives the second booster and is coupled to it in particular in the manner explained above.

In the context of the present invention, the first (cold) booster can in particular provide a stage pressure ratio of 1.5 to 2.2, for example approx. 1.9. Furthermore, due to the comparatively small amount of air that is passed through the second (warm) booster, an equally small amount of air that is expanded by means of the second expansion turbine (but with an expansion of the high third pressure level of, for example, approx 12 bar on one

comparatively low second pressure level of, for example, approx. 1.4 bar and the associated increased production of cold) a stage pressure ratio of 1.4 to 2.1, for example approx. 1.8, can be set.

The cooling capacity to be achieved by the two expansion turbines can be optimally adjusted, since the ratio of the currents through the expansion turbines to those through the boosters can be varied well (with regard to the

specific speeds from expansion turbine to booster). The power of the second expansion turbine (Lachmann turbine) can be completely fed into the process as cold, since it drives a warm booster (in the case of a cold booster, this would not be possible because the cold is fed back into the process as heat from the cold booster will).

By using the second expansion turbine, which corresponds to a Lachmann turbine, the injection equivalent can be increased and thus the overall efficiency of the process can be increased. Due to the improved

Stage pressure ratios can as opposed to the third pressure level

conventional variants can be reduced by approx. 1 to 3 bar, which saves approx. 3% energy in the product constellation examined. The lowering is possible because the increased stage pressure ratios result in a stronger compression of a

enable corresponding air proportion. The investment costs are very similar as the number of devices used is not increased. By heating the material flow compressed by the first booster before further compression in the second booster, the main heat exchanger volume is increased (by approx. 10 to 25%). Due to the lower third pressure level, a

Compressor stage on the main air compressor can be saved.

The present invention enables an overall improvement in the efficiency of high-air pressure interconnections with regard to energy consumption without having to accept a loss of cost advantages compared to main compressor / booster interconnections or conventional high-air pressure interconnections. In the case previously considered, the potential energy consumption is up to 5% lower than in a conventional high-air pressure process with a cold booster. Furthermore, by lowering the pressure on the main air compressor, one compressor stage on the main air compressor can be saved, which reduces the investment costs compared to a high-air pressure process with two cold boosters and one warm booster, saving a turbine unit, which increases the availability of the system.

advantageously represents the only booster that is fed in the system with fluid at a temperature level below -50 ° C, in particular below -100 ° C and down to -150 ° C.

In the method according to the invention, as already mentioned, the additional air, which is supplied to a second expansion turbine, which drives the second booster, at the third or fourth pressure level and is thus expanded to the second pressure level, by a further subset of the first input air volume , which was compressed to the fourth pressure level in the first booster, or formed by a third proportion of the input air quantity at the third pressure level. In the first case, in the example, a further saving of approx. 2% energy can be achieved. Overall, this results in a saving of approx. 5% energy.

In the context of the method according to the invention, the first pressure level is in particular 5 to 7 bar, the second pressure level in particular 1, 3 to 1.9 bar, the third pressure level in particular 11 to 15 bar, the fourth pressure level in particular 18 to 25 bar and the fifth pressure level in particular at 30 to 40 bar. As mentioned, the use of the present invention can in particular lower the third pressure level compared to known methods.

In the context of the present invention, the second portion of the amount of feed air can be fed to the first expansion turbine, in particular at a temperature level of -160 to -130 ° C. The same applies if a

Partial quantity of the first input air quantity, which was compressed to the fourth pressure level using the first booster, is supplied to this first expansion turbine. The first and the second portion of the input air quantity can also be fed jointly to a main heat exchanger of the air separation plant and withdrawn at the respective different temperature levels. However, it is also a completely separate management of the first and second portions of the

Feed air volume possible through the main heat exchanger.

The further air that is supplied to the second expansion turbine, which drives the second booster, can in particular be brought to a temperature level of -90 to -10 ° C., in particular -60

to -30 ° C, before they are fed to the second expansion turbine

will. If this is the mentioned further subset of the first

The amount of air used, which was compressed to the fourth pressure level in the first booster, and which is in a colder state, this additional air is heated accordingly. If, on the other hand, it is the third part of the

The amount of air used at the third pressure level, which is naturally at a higher pressure level, is cooled accordingly.

The air, which was expanded using the second expansion turbine, can be fed to the main heat exchanger and brought to a temperature level

be cooled from -180 to -140 ° C, in particular -170 to -150 ° C, before it is fed to the low-pressure column at the second pressure level.

Furthermore, within the scope of the present invention, a further partial amount of the first input air amount, which was compressed to the fourth pressure level in the first booster, can be cooled to a temperature level of -175 to -155 ° C and then partially or completely fed into the high-pressure column.

The second portion of the feed air quantity, which was expanded to the first pressure level in the first expansion turbine, is in particular partially liquefied by the expansion, after a phase separation a non-liquefied portion of it partially or completely in the high pressure column and a non-liquefied portion partially or completely in the low pressure column can be fed.

In the method according to the invention it is advantageously provided that the partial amount of the input air amount that is in the second booster on the fifth

Pressure level was compressed, then cooled to a temperature level of -175 to -155 ° C and fed into the high pressure column.

The further air, which was expanded to the second pressure level in the second expansion turbine and which can be provided as explained above, can be fed into the low-pressure column in particular after this expansion, as is known with regard to Lachmann turbines.

In the context of the present invention, the first expansion turbine can also be coupled to a braking device, so that larger amounts of air can be used therein

can be relaxed than would be possible with a pure coupling with the first booster. In this way, additional cold can be generated.

In the process according to the invention, one or more liquid streams are advantageously removed from the distillation column system, pressure increased in the liquid state, then evaporated or transferred to a supercritical state and discharged from the air separation plant as into or more pressure products. In the context of the present invention, an internal compression is carried out in particular. The present invention is particularly suitable for internal compression processes in which pressures of less than 25 bar, with respect to the respective printed products produced, are used.

The present invention also extends to an air separation plant for the recovery of one or more air products, the features of which are based on the

corresponding independent claim is referenced.

Features and advantages of those proposed according to the invention

Air separation plant refer to the above explanations regarding the

referred to the method proposed according to the invention expressly.

The same also applies to an air separation plant according to a particularly preferred embodiment of the present invention, which is set up to carry out a method, as has been explained in detail above, and has corresponding means for this purpose.

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

Brief description of the drawings

Figure 1 shows an air separation plant according to an embodiment of the invention in a schematic representation.

Figure 2 shows an air separation plant according to a further embodiment of the invention in a schematic partial representation.

Figure 3 shows an air separation plant according to a further embodiment of the invention in a schematic partial representation.

FIG. 4 shows an air separation plant according to a further embodiment of the invention in a schematic partial representation.

FIG. 5 shows an air separation plant according to a further embodiment of the invention in a schematic partial representation.

In the figures, elements that correspond to one another are given identical reference symbols and are not explained repeatedly for the sake of clarity.

Detailed description of the drawings

In FIG. 1, an air separation plant according to an embodiment of the invention is shown in a greatly simplified, schematic illustration and designated as a whole by 100. For a more detailed explanation in the figure 1 not shown

For system parts, reference is made to specialist literature such as Häring (see above), for example.

In the air separation plant 100, what is not illustrated here individually

Facilities in a so-called warm part 20, a compressed, cleaned and pre-cooled feed air stream a is provided. For example, in the warm part 20 to provide the feed air flow a via a filter, atmospheric air can be sucked in by means of a main air compressor, which can in particular be designed in multiple stages, and which can be followed by one or more aftercoolers, and compressed to a pressure level, which here as " third "pressure level is referred to. The air can then be cooled and, in particular, cleaned up by means of adsorbers.

The air separation process carried out in the air separation plant 100 is a high-air pressure process explained above, so that the third pressure level is at least 3 bar above a pressure level at which a high-pressure column 11 has a

Rectification column system 10 is operated, and which is referred to here as the "first" pressure level. The rectification column system 10 further includes a

Low pressure column 12, which is at a pressure level below the first

Pressure levels is operated, and which is referred to here as the "second" pressure level.

The rectification column system 10 also has a crude argon column 13 and a pure argon column 14, which are not explained in more detail here for reasons of clarity. Again reference is made to specialist literature, in particular Figure 2.3A in Häring (see above) and there also on page 26 ff., "Rectification in the Low-pressure, Crude and Pure Argon Column", and page 29 ff., "Cryogenic Production of Pure Argon ", referenced.

The entire amount of air supplied to the rectification column system 10, which is compressed to the third pressure level, is referred to here as the "feed air amount". In the example shown, this amount of feed air is upstream and within a

Main heat exchanger 3 of the air separation plant 100 is divided into a total of four material flows b, c, d, e, the material flows b and c being fed to the main heat exchanger 3 here initially in the form of a common material flow and the actual formation of the individual material flows b and c only through the removal takes place from the main heat exchanger 3 at different temperature levels.

The material flows b and c are thus fed here together to the main heat exchanger 3 of the air separation plant 100, but preferably to this

taken from different intermediate temperature levels. These temperature levels have already been explained above. The material flow b is then fed to a further compression in a cold booster 1 (referred to here as the “first” booster), which is coupled to a (“first”) expansion turbine 1a. This further

Compression takes place to a pressure level which is referred to here as the "fourth" pressure level. In the first expansion turbine 1a, the material flow c is expanded, in particular to the first pressure level of the high pressure column 11. It is in the

The example shown is partially liquefied by the expansion in the expansion turbine 1 a and then fed into a separator 4. A portion remaining in gaseous form is fed into the high-pressure column 11 in the form of a stream f. Liquid from the separator 4 is expanded into the low-pressure column 12 in the form of a material flow g (see connection point A).

The material flow b is again fed to the main heat exchanger 3 at the fourth pressure level and heated there to a first proportion and then in the form of a

The material flow is fed to a warm ("second") booster 2 and is further compressed there, to a pressure level that is also referred to here as the "fifth" pressure level. Another portion of the material flow b, however, is cooled in the main heat exchanger 3 and in the form of a material flow i, which is also in the

Main heat exchanger 3 cooled streams d and h is combined into the

High pressure column 11 fed. The partial flow h is before it is in the

Main heat exchanger 3 is cooled, cooled in an aftercooler 5. the

Material flows d, h and i are each passed through to the cold end

Main heat exchanger 3 out.

The material flow e is in the main heat exchanger 3 except for one

Intermediate temperature level cooled and then in a ("second")

Relaxation turbine 2a, which is coupled to the second booster 2, relaxes.

This relaxation takes place on the second pressure level. The material flow e is fed into the low-pressure column 12 (see connection point B). The second

Expansion turbine 2a is therefore a typical Lachmann turbine.

The air separation plant 100 is set up for internal compression. In the example shown, nitrogen-rich overhead gas is removed from the high-pressure column 11, liquefied in a main condenser (not specifically designated), which connects the high-pressure column 11 and a low-pressure column 12 in a heat-exchanging manner, and fed in liquid form to an internal compression pump 6 in the form of a material flow k. After the material flow k in the internal compression pump 6 has been brought to a higher, for example a supercritical, pressure level, it is evaporated in the main heat exchanger 3 or converted from the liquid to the supercritical state. A

corresponding nitrogen-rich air product can be released at the system boundary. A liquid, oxygen-rich air product can be extracted from the sump of the

Low-pressure column 12 withdrawn in the form of a stream I, in a

Internal compression pump 7 correspondingly increased in pressure, evaporated in the main heat exchanger 3 or transferred to the supercritical state, and finally as

oxygen-rich air product can be released at the system boundary.

The other material flows shown in FIG. 1 and, in particular, passed through the main heat exchanger 3 can be found in the cited specialist literature. To this extent, the air separation plant 100 operates in a manner customary in the art.

In the figures 2 to 5 parts of air separation plants according to others

Embodiments of the invention are shown schematically in a highly simplified manner. Only the schematically illustrated warm part 20, the main heat exchanger 3, the first booster 1, the first expansion turbine 1a, the second booster 2, the second expansion turbine 2a and the aftercooler 5 are illustrated in each case. The separator 4, the high pressure column 1 1 and the low pressure column 12 are only for

Illustration of the further treatment of the material flows identified in FIG. 1 indicated.

While the interconnection according to FIG. 2 essentially corresponds to that according to FIG. 1 and only the material flows b and c are already upstream of the

Main heat exchanger 1 are formed, the interconnection according to Figure 3 differs essentially from that of Figures 1 and 2 in that the second expansion turbine 2a is supplied with a partial flow of the material flow h instead of the material flow e. This is designated in Figure 3 with e '. The material flow e 'is heated before the expansion in the second expansion turbine 2a, whereas the material flow e of the figures explained above is correspondingly cooled.

The interconnection according to FIG. 4 corresponds to the treatment of the

Substance flow e again in FIG. 2, but a flow conduction according to FIG. 3 can also be provided in this regard. The material flow e expanded in the second expansion turbine 2a is further cooled here in the main heat exchanger 3 to the extent explained above before it is fed to the low-pressure column 12 here.

The interconnection according to FIG. 5 corresponds to the treatment of the

Material flow e again in FIG. 3, but in this regard a flow conduction according to FIG. 2 or 4 can also be provided. Different from the previous ones

Here, in the first expansion turbine 1a, a subset of the first input air volume, which was compressed to the fourth pressure level using the first booster (1), is expanded.

Claims

1. A method for obtaining one or more air products using an air separation plant (100) with a first booster (1), a second booster (2), a first expansion machine (1a) and a

Rectification column system (10), which has a high pressure column (1 1) which is operated at a first pressure level, and a low pressure column (12) which is operated at a second pressure level below the first pressure level, wherein

- The entire air fed to the rectification column system (10) is initially compressed as feed air to a third pressure level which is at least 3 bar above the first pressure level,

- A first proportion of the input air quantity at the third pressure level and a temperature level of -140 to -70 ° C is fed to a first booster (1) and is compressed to a fourth pressure level using the first booster (1),

- A second portion of the feed air quantity or a subset of the first

Feed air quantity, which was compressed to the fourth pressure level using the first booster (1), is fed to a first expansion turbine (1a), using which the first booster (1) is driven, and using the first expansion machine (1 a) to the first pressure level is released,

- A subset of the first amount of feed air that is generated using the

the first booster (1) was compressed to the fourth pressure level, fed to a second booster (2) and compressed to a fifth pressure level using the second booster (2), and

- that the first portion of the input air quantity at the outlet of the first booster (1) is at a temperature level of -120 to -60 ° C,

characterized,

- That the partial quantity of the first input air quantity, which is compressed to the fifth pressure level using the second booster (2), to a temperature level before it is compressed in the second booster (2)

is heated from -20 to 40 ° C.

2. The method according to claim 1, in which further air at the third or fourth pressure level of a second expansion turbine (2a), using which the second booster (2) is driven, is supplied and using the second expansion turbine (2a) on the The second pressure level is relaxed, the additional air being formed by a further subset of the first input air volume, which was compressed to the fourth pressure level in the first booster (1), or by a third portion of the input air volume at the third pressure level.

3. The method according to claim 1 or 2, in which the first pressure level at 5 to 7 bar, the second pressure level at 1, 2 to 1, 9 bar, the third pressure level at 1 1 to 15 bar, the fourth pressure level at 18 to 25 bar and the fifth pressure level is 30 to 40 bar absolute pressure.

4. The method according to any one of the preceding claims, wherein the second portion of the amount of feed air and / or the first expansion turbine (1 a) supplied sub-amount of the first amount of input air, using the first

Booster (1) was compressed to the fourth pressure level, the first

Expansion turbine (1 a) is performed at a temperature level of -160 to -130 ° C.

5. The method of claim 2, wherein the further air that of the second

Expansion turbine (2a), by means of which the second booster (2) is driven, is supplied, is brought to a temperature level of -90 to -10 ° C before it is supplied to the second expansion turbine (2a).

6. The method according to any one of the preceding claims, wherein a further

Partial amount of the first input air volume, which was compressed in the first booster (1) to the fourth pressure level, to a temperature level of -177 ° C

cooled to -160 ° C and then partially or completely fed into the high pressure column (1 1).

7. The method according to any one of the preceding claims, in which the second portion of the input air quantity, which was expanded to the first pressure level in the first expansion turbine (1a), is partially liquefied by the expansion, a non-liquefied portion partially or completely after a phase separation in the high pressure column (1 1) and a liquefied portion is partially or completely fed into the low pressure column (12).

8. The method according to any one of the preceding claims, wherein the partial amount of the input air that was compressed in the second booster (2) to the fifth pressure level, then cooled to a temperature level of -177 ° C to -160 ° C and into the high pressure column (11) is fed.

9. The method according to any one of claims 2 or 5, in which the further air, which was expanded to the second pressure level in the second expansion turbine (2a), is fed into the low-pressure column (12).

10. The method according to any one of claims 2, 5 or 9, wherein the further air that was expanded in the second expansion turbine (2a) to the second pressure level, a main heat exchanger (3) at the second pressure level

Air separation plant (100) is fed and cooled.

1 1. The method according to any one of the preceding claims, wherein the first

Expansion turbine (1 a) is coupled to a braking device.

12. The method according to any one of the preceding claims, wherein from the

Distillation column system (10) one or more liquid material flows are removed, pressure increased in the liquid state, then evaporated or transferred to the supercritical state and discharged from the air separation plant (100) as pressure products.

13. The method according to any one of the preceding claims, in which the first booster (1) is operated with a stage pressure ratio of 1.7 to 2.2 and in which the second booster (2) is operated with a stage pressure ratio of 1.4 to 1.8 is operated.

14. Air separation plant (100) for obtaining one or more air products, with a first booster (1), a second booster (2), a first

Expansion machine (1 a) and with a rectification column system (10) which has a high pressure column (11) which is set up for operation at a first pressure level, and a low pressure column (12) which is for operation at a second pressure level below the first pressure level is set up, having, wherein the air separation plant (100) is set up to

- to compress all of the air fed to the rectification column system (10) initially as feed air to a third pressure level which is at least 3 bar above the first pressure level,

- to feed a first portion of the input air quantity at the third pressure level and a temperature level of -140 to -70 ° C to a first booster (1) and to compress it to a fourth pressure level using the first booster (1),

- A second portion of the feed air quantity or a partial quantity of the first feed air quantity, which has been compressed to the fourth pressure level using the first booster (1), to a first expansion turbine (1a), using which the first booster (1) is driven, and to relax to the first pressure level using the first relaxation machine (1 a),

- A subset of the first amount of feed air that is generated using the

first booster (1) was compressed to the fourth pressure level, a second booster (2) and using the second

To compress boosters (2) to a fifth pressure level, and

- That the air separation plant (100) is set up to provide the first booster (1) with the first portion of the input air volume at a temperature level of -100 to -60 ° C,

characterized,

- That the air separation plant (100) is set up to reduce the partial amount of the first input air amount, which is compressed to the fifth pressure level using the second booster (2), to a temperature level of -20 to before it is compressed in the second booster (2) To be heated to 40 ° C.

15. Air separation plant (100) according to claim 14, which is used to carry out a

Method according to one of claims 2 to 13 is set up.