PROCESS FOR OBTAINING ONE OR MORE AIR PRODUCTS AND AIR SEPARATION PLANT

Abstract

The invention proposes a process and an air separation plant comprising a rectification column system comprising a high-pressure column, a low-pressure column, a main heat exchanger, and a main air compressor. The total air supplied to the rectification column system is compressed in the main air compressor to a first pressure level. The high-pressure column is operated at a second pressure level, at least 3 bar below the first pressure level. A gaseous, nitrogen-rich fluid is removed from the high-pressure column and warmed up in the gaseous state without prior liquefaction. A first partial quantity of the gaseous, nitrogen-rich fluid is warmed to a first temperature level of 150 to 100 C., supplied at this first temperature level to a booster and compressed further to a third pressure level. The first partial quantity is then warmed to a second temperature level and discharged from the air separation plant.

Claims

1. Process for obtaining one or more air products by using an air separation plant (100) with a rectification column system (14-17), which comprises a high-pressure column (14) and a low-pressure column (15), and also with a main heat exchanger (9) and a main air compressor (1), in which the total air supplied to the rectification column system (14-17) is compressed in the main air compressor (1) to a first pressure level, the high-pressure column (15) being operated at a second pressure level, which is at least 3 bar below the first pressure level, and a gaseous, nitrogen-rich fluid is removed from the high-pressure column (15) at the second pressure level and warmed up in the gaseous state without prior liquefaction, characterized in that a first partial quantity of the gaseous, nitrogen-rich fluid is warmed up to a first temperature level of 150 to 100 C., in particular of 140 to 120 C., supplied at this first temperature level to a booster (12), and by using the booster (12) compressed further to a third pressure level, and the first partial quantity after compression to the third pressure level is warmed up to a second temperature level above the first temperature level and discharged permanently from the air separation plant (100).

2. Process according to claim 1, in which a second partial quantity of the gaseous nitrogen-rich fluid is warmed up together with the first partial quantity to the first temperature level, supplied at this temperature level to the booster (12), and compressed further to the third pressure level by using the booster (12), the second partial quantity after compression to the third pressure level being cooled down to a third temperature level below the first temperature level, subsequently expanded to the second pressure level and returned into the high-pressure column (15).

3. Process according to claim 2, in which a third partial quantity of the nitrogen-rich fluid without compression to the third pressure level is warmed up to the first temperature level and discharged permanently from the air separation plant (100).

4. Process according to claim 2, in which the first and second partial quantities are warned up to the first temperature level by using the main heat exchanger (9), and/or the first partial quantity is warmed up to the second temperature level by using the main heat exchanger (9) and/or in which the second partial quantity is cooled down to the third temperature level by using the main heat exchanger (9).

5. Process according to claim 1, in which the third pressure level is at 8 to 12 bar.

6. Process according to claim 1, in which the booster (12) is mechanically coupled to an expansion turbine (11), in particular a part of the air which is supplied to the rectification column system (14-17) and has previously been cooled down to a fourth temperature level by using the main air compressor (9) and subsequently fed into the high-pressure column (14) being expanded to the second pressure level in the expansion turbine (11) coupled to the booster (12).

7. Process according to claim 1, in which the booster (12) is driven by using external energy, in particular by means of an electric motor (M).

8. Process according to claim 2, in which the second partial quantity comprises a fraction of 10 to 50% of the gaseous nitrogen-rich fluid that is removed from the high-pressure column (15) at the second pressure level and warmed up in the gaseous state without prior liquefaction.

9. Process according to claim 1, in which a part of the air that is supplied to the rectification column system (14-17) is compressed in a further booster (6) from the first pressure level to a fifth pressure level, cooled down to a fifth temperature level by using the main heat exchanger (9), expanded to the second pressure level in an expansion turbine (7) mechanically coupled to the further booster (6), and subsequently fed into the high-pressure column (14).

10. Process according to claim 9, in which a part of the air that is supplied to the rectification column system (14-17) is compressed from the first pressure level to the fifth pressure level in the further booster (6), cooled down to a sixth temperature level by using the main heat exchanger (9), expanded to the second pressure level, and subsequently fed into the high-pressure column (14).

11. Process according to claim 1, in which a part of the air that is supplied to the rectification column system (14-17) is cooled down at the first pressure level by using the main heat exchanger (9), expanded from the first pressure level to the second pressure level, and subsequently fed into the high-pressure column (14).

12. Process according to claim 1, in which the rectification column system (14-17) comprises at least one rectification column (16), into which a first fluid that is enriched in argon with respect to a sump liquid of the high-pressure column (15) is transferred from the low-pressure column (15), and in which the first fluid is depleted of argon, a residue of the first fluid that remains after the argon depletion being returned into the low-pressure column (15).

13. Process according to claim 12, in which a crude argon column (16) and a pure argon column (17) are used, operated with top condensers in which oxygen-enriched liquid from the sump of the high-pressure column (14) is partially evaporated, a non-evaporated fraction from the top condenser of the pure argon column (17) being fed back into the low-pressure column (15) 5 to 15 theoretical separating stages above the feeding-in of the non-evaporated fraction from the top condenser of the crude argon column (16).

14. Plant (100) for obtaining one or more air products, with a rectification column system (14-17), which comprises a high-pressure column (14) and a low-pressure column (15), and also with a main heat exchanger (9) and a main air compressor, the plant (100) having means which are designed for compressing the total air supplied to the rectification column system (14-17) in the main air compressor (1) to a first pressure level and operating the high-pressure column (15) at a second pressure level, which is at least 3 bar below the first pressure level, and removing a gaseous, nitrogen-rich fluid from the high-pressure column (15) at the second pressure level and warming it up in the gaseous state without prior liquefaction, characterized by means which are designed for warming up a first partial quantity of the gaseous, nitrogen-rich fluid to a first temperature level of 150 to 100 C., in particular of 140 to 120 C., supplying it at this first temperature level to a booster (12), and by using the booster (12) compressing it further to a third pressure level, and warming up the first partial quantity after compression to the third pressure level up to a second temperature level above the first temperature level and discharging it permanently from the air separation plant (100).

Description

BRIEF DESCRIPTION OF THE DRAWING

[0053] FIG. 1 shows an air separation plant according to one embodiment of the invention in a schematic representation.

[0054] FIG. 2 shows an air separation plant according to one embodiment of the invention in a schematic representation.

[0055] FIG. 3 shows an air separation plant according to one embodiment of the invention in a schematic representation.

[0056] FIG. 4 shows an air separation plant according to one embodiment of the invention in a schematic representation.

DETAILED DESCRIPTION OF THE DRAWING

[0057] In FIG. 1, an air separation plant according to one embodiment of the invention is shown in a simplified, schematic representation and is denoted by 100.

[0058] In the air separation plant 100, a feed air stream a (AIR) is drawn in by means of a main air compressor 1 via a filter 2 and compressed to a pressure level which is referred to here as the first pressure level. The main air compressor 1 may be designed in particular in multiple stages with intermediate cooling. A cooler assigned to the main air compressor 1 is shown as representative of a number of corresponding coolers and is denoted by 3.

[0059] The air separation process carried out in the air separation plant 100 is a high air pressure process explained above, so that the first pressure level lies at least 3 bar above a pressure level at which a high-pressure column 14 of a rectification column system (see below) of the air separation plant 100 is operated, and which is referred to here as the second pressure level.

[0060] The total quantity of air fed to the rectification column system, which is compressed to the first pressure level, is referred to here as the feed air quantity. This feed air quantity is first cooled in the form of the feed air stream a in a cooling device 4, and subsequently freed at least largely of water and carbon dioxide in an adsorption device 5. With respect to the operating principle of the cooling device 4 and the adsorption device 5, reference should be made to specialist literature such as Haring (see above). The cooling device 4 is operated in the way described with cooling water (H2O); the adsorption device 5 is regenerated with regenerating gas, which after its use can be given off to the atmosphere (ATM). The cooled and purified feed air stream a, which to allow better differentiation is thus denoted by b, is first divided into two partial streams c and d.

[0061] The partial stream c is brought to a pressure level above the first pressure level in a booster 6, which is mechanically coupled to an expansion turbine 7, and after cooling in an aftercooler is once again divided into two partial streams e and f, which are supplied to a main heat exchanger 9 of the air separation plant 100. Since the partial stream e is supplied to the booster 6 at ambient temperature or above, but at least at a temperature level above 0 C., it is also referred to as a warm booster. The partial stream e is removed from the main heat exchanger 9 at an intermediate temperature level, expanded in the expansion turbine 7 and fed into the high-pressure column 14 in an at least partially gaseous state. The partial stream f is removed from the main heat exchanger 9 on the cold side and fed into the high-pressure column 14 in a liquid state via a throttle 10. The partial stream f is therefore a first throttle stream.

[0062] The partial stream c is likewise divided once again into two partial streams g and h, which are supplied to the main heat exchanger 9 of the air separation plant 100. The partial stream g is removed from the main heat exchanger 9 at an intermediate temperature level, expanded in an expansion turbine 11, which is mechanically coupled to a booster 12, and fed into the high-pressure column 14 in an at least partially gaseous state. It is in this case previously combined with the partial stream e. Since, as explained below, fluid that is significantly below ambient temperature, but at least significantly below 0 C., 10 C., 20 C., 30 C., 40 C., 50 C., is supplied to the booster 12, it is also referred to as a cold booster. The partial stream h is removed from the main heat exchanger 9 on the cold side and fed into the high-pressure column 14 in a liquid state via a throttle 13. It is in this case previously combined with the partial stream f or fed into the high-pressure column 14 directly. The partial stream h is therefore a second throttle stream.

[0063] The operation of the rectification column system, which in the air separation plant 100 comprises the already mentioned high-pressure column 14, a low-pressure column 15, a crude argon column 16 and a pure argon column 17, can in principle be taken from the specialist literature cited at the beginning.

[0064] The air separation plant 100 is designed for internal compression. In the example presented, for this purpose an oxygen-rich sump product in the form of a stream of matter i is removed in liquid form from the low-pressure column 15 and a fraction thereof in the form of a stream of matter k is brought to around 30 bar(a) or to a higher pressure level, for example to a supercritical pressure level, in an internal compression pump 18, evaporated or transformed from the liquid state into the supercritical state in the main heat exchanger 9, and given off as an internally compressed oxygen-rich air product (GOX IC) at the periphery of the plant. A further fraction of the stream of matter i is not internally compressed, instead is passed to the periphery of the plant in the form of a stream of matter I and given off there as a liquid oxygen product (LOX). The temperature may in this case be set by partially passing the stream of matter I through a counter-current subcooler 19.

[0065] Oxygen-enriched liquid in the form of a stream of matter m can be removed from the sump of the high-pressure column 14. The stream of matter m may be passed through the counter-current subcooler 19 and subsequently fed in fractions into the respective evaporation spaces of the top condensers of the crude argon column 16 and the pure argon column 17. Liquid and gaseous fractions removed from these evaporation spaces are fed into the low-pressure column 15. The crude argon column 16 and the pure argon column 17 are operated in a known way. In particular, an argon-enriched fluid in the form of a stream of matter n is removed at a suitable position from the low-pressure column 15 and in the crude argon column 16 is depleted of oxygen, which is returned into the low-pressure column 15. Nitrogen-containing crude argon is transferred in the form of a stream of matter o into the pure argon column, where in particular nitrogen can be separated off and given off to the atmosphere (ATM). Liquid argon (LAR) may be given off as product at the periphery of the plant.

[0066] Gas may be removed from the top of the low-pressure column 15 and passed in the form of a stream of matter p through the counter-current subcooler 19, and subsequently through the main heat exchanger 9 (see also link A), and can be partly used as the already mentioned regenerating gas in the adsorption device 5 after warming up in a heating device 20. It is also possible in principle for it to be given off to the atmosphere (ATM), for example at times in which no regenerating gas is required. A liquid, nitrogen-rich stream of matter q may be drawn off from a tray in an upper region of the low-pressure column 15 and given off as liquid product (LIN) at the periphery of the plant.

[0067] Liquid air may be drawn from the high-pressure column 14 in the form of a stream of matter r, passed through the counter-current subcooler 19 and fed into the low-pressure column 15. Nitrogen-rich gas in the form of a stream of matter s may be drawn off from the top of the high-pressure column. This may be partly liquefied in the form of a stream of matter tin a main condenser 21, connecting the high-pressure column 14 and the low-pressure column 15 in a heat-exchanging manner, and used as reflux to the high-pressure column 14, and also be passed through the counter-current subcooler 19 and fed into the low-pressure column 15.

[0068] A further aspect of the present invention in the embodiment illustrated is the treatment of the fraction of the stream of matter s that is not passed through the main condenser 21. Since it has been removed from the high-pressure column, it is at the pressure level of the latter, the second pressure level, and in the example represented is supplied to the main heat exchanger 9 on the cold side in the form of a stream of matter u. A partial stream v is removed from the main heat exchanger 9 on the warm side and for example provided as seal gas.

[0069] A further partial stream w is removed from the main heat exchanger 9 at an intermediate temperature level, which is referred to here as the first temperature level, and in the already mentioned booster 12 is brought to a pressure level above the second pressure level, which is referred to here as the third pressure level. In turn, a partial stream x of the partial stream w is again supplied to the main heat exchanger 9, removed from it on the cold side, that is to say is cooled down to a temperature level that is referred to here as the third temperature level, expanded in the liquid state via a throttle 22 and returned into an upper region of the high-pressure column 14. The partial stream x is therefore a further throttle stream.

[0070] On the other hand, a further partial stream y of the partial stream w is warmed up in the main heat exchanger 9 to a temperature level that is referred to here as the second temperature level, and is given off as a gaseous pressurized nitrogen product at the periphery of the plant.

[0071] In other words, here a first partial quantity and a second partial quantity in the form of the streams of matter y and x of a nitrogen-rich fluid that is removed from the high-pressure column 15 in the form of a stream of matter u at the second pressure level and warmed up by using the main heat exchanger 9 are warmed up to the first temperature level by using the main heat exchanger 9, supplied at this temperature level to the booster 12, and compressed further to the third pressure level by using the booster 12. After compression to the third pressure level, the first partial quantity, i.e. the stream of matter y, is warmed up to a second temperature level above the first temperature level by using the main heat exchanger 9 and is permanently discharged from the air separation plant. After compression to the third pressure level, the second partial quantity, i.e. the stream of matter x, is cooled down to the third temperature level by using the main heat exchanger 9, expanded to the second pressure level and returned into the high-pressure column 15.

[0072] FIG. 2 shows an air separation plant according to a further embodiment of the invention in a schematic representation, no description being given of components that have already been explained in relation to FIG. 1. They are also not provided again with designations.

[0073] As illustrated in FIG. 2, a part of the nitrogen-rich gas liquefied in the main condenser 21, comparable to the stream of matter k according to plant 100 or FIG. 1 (see link X in FIG. 2), is also compressed by means of a further internal compression pump 201, warmed up in the main heat exchanger 9 and subsequently provided as an internally compressed, gaseous nitrogen product (GAN IC).

[0074] FIG. 3 shows an air separation plant according to a further embodiment of the invention in a schematic representation. Once again, no description is given of components that have already been explained in relation to FIG. 1 or 2. They are also not provided again with designations.

[0075] As illustrated in FIG. 3, instead of the partial stream g, which is formed by the partial stream c, a further partial stream 301 of the partial stream d, which as a result of the compression in the booster 6 is at a higher pressure level than the partial stream c, may alternatively also be supplied to the expansion turbine 11. The partial stream g is in this case not formed.

[0076] FIG. 4 shows an air separation plant according to a further embodiment of the invention in a schematic representation. As before, here too no description is given of components that have already been explained in relation to the previous figures, and they are not provided again with designations here either.

[0077] As represented in FIG. 4, the booster 12 may also be driven by using external energy, for example by using an electric motor M. In this way, it is possible to dispense with the separate provision of a stream of matter g (FIG. 1) or 301 (FIG. 3).

[0078] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

[0079] In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

[0080] The entire disclosures of all applications, patents and publications, cited herein and of corresponding European application No. 17020238.6, filed Jun. 2, 2017 are incorporated by reference herein.

[0081] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0082] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.