METHOD AND PLANT FOR PROVIDING A PRESSURIZED OXYGEN-RICH, GASEOUS AIR PRODUCT

Abstract

The invention relates to a high-atmospheric-pressure method for producing a pressurized oxygen-rich, gaseous air product. A first partial quantity of the feed air quantity is supplied at a temperature in a first temperature range to a first turbine unit (5), decompressed using same, and fed into a high-pressure column (111). A second partial quantity of the feed air quantity is supplied at a temperature in a second temperature range to a second turbine unit (6), decompressed using same, and fed into a low-pressure column (12). The pressurized, oxygen-rich air product is provided as an internal compression product at 16 to 50 bar, wherein evaporation is effected proceeding from a temperature in a third temperature range. The third temperature range lies above the first and second temperature range, the second temperature range is selected such that a two-phase mixture with a liquid proportion of 5 to 15% forms at the outlet of the second turbine unit (6), the temperature in the first temperature range and the temperature in the second differ from each other by not more than 10 K, and a portion of less than 5% of all air products removed from the air separation plant (100) is removed from the air separation plant in an unevaporated and liquid state. The first turbine unit is braked by a cold compressor (4), the second by a generator (G) or a warm booster. The invention also relates to an air separation plant (100).

Claims

1. A method for producing a pressurized, oxygen-rich, gaseous air product using an air separation plant comprising a rectification column system having a high-pressure column and a low-pressure column and a main heat exchanger, a first turbine unit, and a second turbine unit, wherein the high-pressure column is operated in a first pressure range of from 4 to 7 bar, the low-pressure column is operated in a second pressure range of from 1 to 2 bar, and at least a predominant portion of a total feed air quantity supplied to the rectification column system is compressed to a pressure in a third pressure range which is more than 3 bar above the first pressure range, a first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is supplied to the first turbine unit at the pressure in the third pressure range or at a pressure in a fourth pressure range above the third pressure range and at a temperature in a first temperature range, decompressed to a pressure in the first pressure range using the first turbine unit, and fed into the high-pressure column, a second partial quantity of the feed air quantity compressed to the pressure in the third pressure range is supplied to the second turbine unit at the pressure in the third pressure range or at a pressure in a fifth pressure range above the third pressure range and at a temperature in a second temperature range, decompressed to a pressure in the second pressure range using the second turbine unit, and fed into the high-pressure column, oxygen-rich liquid is withdrawn from the rectification column system to provide the gaseous, pressurized, oxygen-rich air product, brought to a pressure in a sixth pressure range of from 16 to 50 in a liquid state, supplied to the main heat exchanger, evaporated therein at the temperature in the third temperature range and discharged from the air separation plant, wherein the second temperature range is selected such that a two-phase mixture having a liquid proportion of 5 to 15% forms at the outlet of the second turbine unit, a proportion of less than 5% of all air products withdrawn from the air separation plant is withdrawn from the air separation plant in an unevaporated and liquid state wherein the third temperature range is above the first temperature range and the second temperature range, the temperature in the first temperature range and the temperature in the second differ from each other by not more than 10 K, the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is provided at the pressure in the fourth pressure range and is thereby brought to the pressure in the fourth pressure range using a booster unit, the first turbine unit is used to drive the booster unit, and the second turbine unit is coupled to a generator or to a warm booster for air.

2. The method according to claim 1, wherein the first and second temperature ranges are 110 to 140 K.

3. The method according to claim 1, wherein the third temperature range is more than 10 K above the second temperature range.

4. The method according to claim 1, wherein the booster unit is formed by a cold compressor.

5. The method according to claim 1, wherein the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is cooled in a first cooling step in the main heat exchanger before it is brought to the pressure in the fourth pressure range using the booster unit, and wherein the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range can be cooled in a second cooling step in the main heat exchanger after it has been brought to the pressure in the fourth pressure range using the booster unit, wherein the second cooling step comprises cooling to the temperature in the first temperature range.

6. The method according to claim 5, wherein a third partial quantity of the feed air quantity compressed to the pressure in the third pressure range is subjected to the first cooling step together with the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range and brought to the pressure in the fourth pressure range using the booster unit, wherein the third partial quantity of the feed air quantity compressed to the pressure in the third pressure range is liquefied at the pressure in the fourth pressure range in the main heat exchanger, subsequently decompressed, and fed into the high-pressure column.

7. The method according to claim 1, wherein the second partial quantity of the feed air quantity compressed to the pressure in the third pressure range is provided at the pressure in the fifth pressure range and is thereby brought to the pressure in the fifth pressure range using a further booster unit.

8. The method according to claim 1, wherein the two-phase mixture forming at the outlet of the second turbine unit is supplied to a phase separation and is then fed into the low-pressure column in a separate phase.

9. The method according to claim 1, wherein the two-phase mixture forming at the outlet of the second turbine unit is fed biphasically into the low-pressure column.

10. An air separation plant which is configured for producing a pressurized, oxygen-rich, gaseous air product and comprises a rectification column system having a high-pressure column and a low-pressure column, as well as a main heat exchanger, a first turbine unit and a second turbine unit, wherein the air separation plant is configured to operate the high-pressure column in a first pressure range of from 4 to 7 bar, operate the low-pressure column in a second pressure range of from 1 to 2 bar, and compress at least a predominant proportion of a feed air quantity supplied overall to the rectification column system to a pressure in a third pressure range which is more than 3 bar above the first pressure range, supply a first partial quantity of the feed air quantity compressed to the pressure in the third pressure range to the first turbine unit at the pressure in the third pressure range or at a pressure in a fourth pressure range above the third pressure range and at a temperature in a first temperature range, decompress it to a pressure in the first pressure range using the first turbine unit, and feed it into the high-pressure column, supply a second partial quantity of the feed air quantity compressed to the pressure in the third pressure range to the second turbine unit at the pressure in the third pressure range or at a pressure in a fifth pressure range above the third pressure range and at a temperature in a second temperature range, decompress it to a pressure in the second pressure range using the second turbine unit, and feed it into the high-pressure column, remove oxygen-rich liquid from the rectification column system to provide the gaseous, pressurized, oxygen-rich air product, bring it to a pressure in a sixth pressure range of from 16 to 50 bar in the liquid state with heating to a temperature in a third temperature range, evaporate it in the main heat exchanger at the temperature in the third temperature range, and discharge it from the air separation plant, and remove a portion of less than 5% of all air products of the air separation plant removed from the air separation plant in an unevaporated and liquid state, wherein the second temperature range is selected such that a two-phase mixture having a liquid proportion of 5 to 15% forms at the outlet of the second turbine unit, wherein the air separation plant is configured, by removal from the main heat exchanger at suitable positions, so that the third temperature range is above the first temperature range and the second temperature range, the temperature in the first temperature range and the temperature in the second differ from each other by not more than 10 K, and the air separation plant is configured such that the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is provided at the pressure in the fourth pressure range and is thereby brought to the pressure in the fourth pressure range using a booster unit, the first turbine unit is used to drive the booster unit, and the second turbine unit is coupled to a generator or to a warm booster for air.

11. The air separation plant according to claim 10, wherein the booster unit is formed by a cold compressor.

12. The air separation plant according to claim 11, which is configured to carry out a method for producing a pressurized, oxygen-rich, gaseous air product using the air separation plant, wherein the high-pressure column is operated in a first pressure range of from 4 to 7 bar, the low-pressure column is operated in a second pressure range of from 1 to 2 bar, and at least a predominant portion of a total feed air quantity supplied to the rectification column system is compressed to a pressure in a third pressure range which is more than 3 bar above the first pressure range, a first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is supplied to the first turbine unit at the pressure in the third pressure range or at a pressure in a fourth pressure range above the third pressure range and at a temperature in a first temperature range, decompressed to a pressure in the first pressure range using the first turbine unit, and fed into the high-pressure column, a second partial quantity of the feed air quantity compressed to the pressure in the third pressure range is supplied to the second turbine unit at the pressure in the third pressure range or at a pressure in a fifth pressure range above the third pressure range and at a temperature in a second temperature range, decompressed to a pressure in the second pressure range using the second turbine unit, and fed into the high-pressure column, oxygen-rich liquid is withdrawn from the rectification column system to provide the gaseous, pressurized, oxygen-rich air product, brought to a pressure in a sixth pressure range of from 16 to 50 in a liquid state, supplied to the main heat exchanger, evaporated therein at the temperature in the third temperature range and discharged from the air separation plant, wherein the second temperature range is selected such that a two-phase mixture having a liquid proportion of 5 to 15% forms at the outlet of the second turbine unit, a proportion of less than 5% of all air products withdrawn from the air separation plant is withdrawn from the air separation plant in an unevaporated and liquid state wherein the third temperature range is above the first temperature range and the second temperature range, the temperature in the first temperature range and the temperature in the second differ from each other by not more than 10 K, the first partial quantity of the feed air quantity compressed to the pressure in the third pressure range is provided at the pressure in the fourth pressure range and is thereby brought to the pressure in the fourth pressure range using a booster unit, the first turbine unit is used to drive the booster unit, and the second turbine unit is coupled to a generator or to a warm booster for air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIGS. 1 to 5 illustrate air separation plants according to preferred embodiments of the invention.

[0054] FIGS. 6 and 7 show temperature enthalpy diagrams.

DETAILED DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 illustrates an air separation plant, denoted by 100, according to a preferred embodiment of the invention. The air separation plant 100 comprises a rectification column system 10 having a high-pressure column 11 and a low-pressure column 12, which are connected in a known manner.

[0056] Air separation plants of the type shown are often described elsewhere, for example in H?ring (see above), in particular section 2.2.5 there, Cryogenic Rectification. For detailed explanations regarding structure and operating principle, reference is therefore made to corresponding technical literature. An air separation plant for use of the present invention can be designed in a wide variety of ways.

[0057] In the embodiment illustrated here, the high-pressure column 11 is operated in a first pressure range, the low-pressure column 12 is operated in a second pressure range, and at least a predominant portion of a feed air quantity supplied overall to the rectification column system 10, here in the form of a compressed air stream a, is compressed to a pressure in a third pressure range which is significantly above the first pressure range.

[0058] In the air separation plant 100 illustrated in FIG. 1, feed air is drawn in by means of a main air compressor 1, compressed to the pressure in the third pressure range, cooled in a direct contact cooler, likewise not denoted separately, and in particular freed of water and carbon dioxide in a pre-purification unit 2.

[0059] The feed air provided in this way as the mentioned compressed air stream a at the pressure in the third pressure range is then divided into two partial streams b and c, which both are supplied to a main heat exchanger 3 on the hot side and are cooled therein. In each case, further partial streams are formed by removal at intermediate temperature levels and on the cold side of the main heat exchanger 3, which partial streams here represent partial quantities of the feed air of the compressed air stream a, referred to as first to fourth partial quantities, and are indicated by a1 to a4.

[0060] In the embodiment illustrated here, the first partial quantity of the total feed air quantity of the compressed air stream a compressed to the pressure in the third pressure range is supplied to a first turbine unit 5 at a pressure in a fourth pressure range above the third pressure range and at a temperature in a first temperature range in the form of the partial stream a1, decompressed to a pressure in the first pressure ranged using the first turbine unit 5, and fed into the high-pressure column 11.

[0061] The first partial quantity, i.e., the partial stream a1, is thereby brought to the pressure in the fourth pressure range as part of the partial stream b using a booster unit 4, wherein the booster unit 4 is driven by the first turbine unit 5. In a first cooling step, the first partial quantity, i.e., the partial stream a1, is cooled in the main heat exchanger 3 before it is brought to the pressure in the fourth pressure range using the booster unit 4, and the first partial quantity, i.e., the substance stream a1, is cooled in the main heat exchanger 3 in a second cooling step after it has been brought to the pressure in the fourth pressure range using the booster unit 4. The second cooling step comprises cooling to the temperature in the aforementioned first temperature range.

[0062] In the embodiment illustrated here, on the other hand, the second partial quantity of the feed air quantity of the compressed air flow a compressed to the pressure in the third pressure range is supplied to a second turbine unit 6 as part of the partial stream c at the pressure in the third pressure range and at a temperature in a second temperature range in the form of the partial stream a2, which turbine unit 6, in the embodiment illustrated here, is coupled to a generator G, decompressed to a pressure in the second pressure range using the second turbine unit 6, and then fed into the low-pressure column 12.

[0063] The second temperature range is selected in such a way that a two-phase mixture with the liquid portion previously indicated several times forms at the outlet of the second turbine unit 6. In the embodiment illustrated here, the two-phase mixture forming at the outlet of the second turbine unit 6 is supplied in a phase separator 7 in the embodiment of a phase separation illustrated here and then fed into the low-pressure column 12 in a separate phase in the form of a liquid stream a2l and a gas stream a2g.

[0064] The third partial quantity of the feed air quantity of the compressed air stream a compressed to the pressure in the third pressure range is subjected to the first cooling step in the form of the mentioned partial stream a3 together with the first partial quantity, i.e., the partial stream a1, and thus as part of the partial stream b, and is likewise brought to the pressure in the fourth pressure range using the booster unit 4, wherein the third partial quantity, i.e., the partial stream a3, is, however, liquefied in the main heat exchanger 3 at the pressure in the fourth pressure range, decompressed, and fed into the high-pressure column 11.

[0065] The fourth partial quantity of the feed air quantity of the compressed air stream a compressed to the pressure in the third pressure range is supplied to the main heat exchanger 3 in the form of the mentioned partial stream a4 together with the second partial quantity, i.e., the partial stream a2, and thus as part of the partial stream c, but is not removed from the second heat exchanger 3 at the temperature in the second temperature range, but is instead also liquefied in the main heat exchanger, then decompressed, and fed into the high-pressure column 11.

[0066] In the embodiment illustrated here, the partial streams a3 and a4 used as throttle streams are combined to form a total stream k before they are fed into the high-pressure column 11.

[0067] To provide the gaseous, pressurized, oxygen-rich air product, oxygen-rich liquid in the form of a material stream I is withdrawn from the rectification column system 10, more precisely a sump of the low-pressure column 11, brought in a liquid state to a pressure in a sixth pressure range by means of an internal compression pump 8 while heating to a temperature in a third temperature range, evaporated to the temperature in the third temperature range in the main heat exchanger 3 and discharged from the air separation plant 100.

[0068] For further interconnection of the components of the air separation plant 100, which in particular can also comprise a subcooling counter-flow heat exchanger 9, reference is made to the cited technical literature. In particular, only a small portion of air products is removed from the air separation plant 100 in an unevaporated and liquid state, for example in the form of a liquid oxygen stream m.

[0069] The air separation plant 200 according to FIG. 2 differs from the air separation plant 100 according to FIG. 1 substantially by the absence of the phase separator 7, wherein the two-phase stream a2 is fed biphasically into the low-pressure column 12.

[0070] The air separation plant 300 according to FIG. 3 differs from the air separation plants 100 and 200 according to FIGS. 1 and 2 substantially by the provision of the pressurized, oxygen-rich air product in the form of two fractions or partial streams 11 and 12, which are formed from the partial stream I and are evaporated in the main heat exchanger 3 at different pressures.

[0071] The air separation plant 400 according to FIG. 4 differs from the air separation plants 100 to 300 according to FIGS. 1 to 4 substantially in that the second partial quantity a2 (and the fourth partial quantity a4) of the feed air quantity compressed to the pressure in the third pressure range is provided at a pressure in a fifth pressure range and thereby is brought to the pressure in the fifth pressure range using a further booster unit 41, which is driven in particular by the turbine 6 (i.e., self-boosted). The further booster unit 41 is formed by a warm booster, i.e., by a booster having an inlet temperature above 273 K.

[0072] The air separation plant 500 according to FIG. 5 differs from the air separation plants 100 to 400 according to FIGS. 1 to 4 substantially in that an argon discharge column 51 is used in a manner known per se, as described, for example, in EP 3 067 649 A1. A gaseous stream s enriched in argon is drawn off from the argon removal column 51 and heated in the main heat exchanger 3. The argon discharge column 51 is fed from the low-pressure column 12 and sump liquid (in each case without a separate designation) is returned to the low-pressure column 12 after being depleted of argon. To cool a top condenser of the argon discharge column 51, sump liquid from the high-pressure column 11 is used, which is fed into the low-pressure column 12 after partial evaporation

[0073] An argon discharge column in this case refers to a separating column for argon-oxygen separation which is not used to obtain a pure argon product, but rather to discharge argon from the air to be separated in the pressure column and low-pressure column. Its circuit differs only slightly from that of a conventional crude argon column, however it contains significantly fewer theoretical plates, namely less than 40, in particular between 35 and 15. Like a crude argon column, the sump region of an argon discharge column is connected to an intermediate point of the low-pressure column, and the argon discharge column is cooled by a top condenser, on the evaporation side of which expanded sump liquid from the high-pressure column is introduced; an argon discharge column does not have a sump evaporator.

[0074] FIGS. 6 and 7 show temperature enthalpy diagrams of the main heat exchanger 3 of an air separation plant according to an embodiment of the invention, for example an air separation plant 100 to 500 according to FIGS. 1 to 5, wherein in each case a temperature is plotted on the vertical axis in K relative to an enthalpy sum in kW plotted on the horizontal axis and the diagram according to FIG. 7 corresponds to an enlarged representation of the diagram according to FIG. 6. The temperature points Ta1 and Ta2 correspond in each case to the removal temperature level of the partial streams a1 and a2.

[0075] The air separation plants according to FIGS. 1 to 5 can of course also be adapted to yield a low-pressure nitrogen product (LPGAN) as a secondary product of the air separation. This can be done analogously by using a corresponding separation section in the low-pressure column 12.