PROCESS AND PLANT FOR PROVISION OF OXYGEN PRODUCT

Abstract

A process for providing an oxygen product using an air separation plant having a distillation column system, in which a cryogenic liquid is withdrawn from the distillation column system, wherein a first portion of the cryogenic liquid is subjected to a pressure-increasing evaporation by evaporating a second portion of the cryogenic liquid, and the oxygen product is provided using at least part of the first portion of the cryogenic liquid. At least part of the evaporated second portion of the cryogenic liquid, after the increase in pressure, is made available for further utilization, for the provision of the oxygen product. The present invention also relates to a corresponding air separation plant.

Claims

1. A method for providing an oxygen product using an air separation plant with a distillation column system, in which a cryogenic liquid is withdrawn from the distillation column system, wherein a first portion of the cryogenic liquid is subjected to a pressurization vaporization by vaporization of a second portion of the cryogenic liquid, and the oxygen product is provided using at least a part of the first portion of the cryogenic liquid, wherein at least a part of the vaporized second portion of the cryogenic liquid is supplied to utilization for providing the oxygen product.

2. The method according to claim 1, in which the further utilization comprises a material utilization and/or a thermal utilization and/or a pressure utilization.

3. The method according to claim 1, in which the distillation column system comprises a first distillation column, wherein liquid is withdrawn from the first distillation column, expanded, and vaporized against condensing top gas of the first distillation column, which is at least partially returned to the first distillation column, wherein the vaporized liquid is at least partially recompressed and fed back into the first distillation column.

4. The method according to claim 3, in which further liquid is withdrawn from the first distillation column, expanded, vaporized against the condensing top gas of the first distillation column, and at least partially discharged from the air separation plant.

5. The method according to claim 3, in which the distillation column system comprises a second distillation column fed from the first distillation column or any further distillation column downstream of the first distillation column, wherein the second or further distillation column is operated using a sump boiler, and the cryogenic liquid is withdrawn from the second or further distillation column.

6. The method according to claim 5, in which the vaporized second portion of the cryogenic liquid, or the part thereof which is supplied to the further utilization for providing the oxygen product, is at least partially fed into the second distillation column.

7. The method according to claim 5, in which the vaporized second portion of the cryogenic liquid, or the part thereof which is supplied to the further utilization for providing the oxygen product, is at least partially fed to the cryogenic liquid withdrawn from the second distillation column before the pressurization vaporization.

8. The method according to claim 5, in which the vaporized second portion of the cryogenic liquid, or the part thereof which is supplied to the further utilization for providing the oxygen product, is cooled at least partially in the sump boiler of the second or further distillation column from which the cryogenic liquid is taken.

9. The method according to claim 5, in which the vaporized second portion of the cryogenic liquid, or the part thereof which is supplied to the further utilization for providing the oxygen product, is cooled at least partially in a further heat exchanger and/or in the main heat exchanger of the air separation plant.

10. The method according to claim 1, in which the cryogenic liquid and the oxygen product have an oxygen content of more than 99 mole percent.

11. The method according to claim 1, in which a tank system with one or more alternately filled and emptied tanks is used in the pressurization vaporization, wherein in each case the filled tank is pressurized by vaporization of the second portion of the cryogenic liquid, and the second portion of the cryogenic liquid is discharged from the respectively emptied tank.

12. An air separation plant configured to provide an oxygen product, with a distillation column system and means configured to withdraw a cryogenic liquid from the distillation column system, wherein means are provided that are configured to subject a first portion of the cryogenic liquid to a pressurization vaporization by vaporizing a second portion of the cryogenic liquid, and to provide the oxygen product using at least a part of the first portion of the cryogenic liquid, having means configured to supply at least a part of the vaporized second portion of the cryogenic liquid to further utilization for providing the oxygen product after the pressure increase.

13. The air separation plant according to claim 12, which is configured to carry out a method for providing an oxygen product using an air separation plant with a distillation column system, in which a cryogenic liquid is withdrawn from the distillation column system, wherein a first portion of the cryogenic liquid is subjected to a pressurization vaporization by vaporization of a second portion of the cryogenic liquid, and the oxygen product is provided using at least a part of the first portion of the cryogenic liquid, wherein at least a part of the vaporized second portion of the cryogenic liquid is supplied to utilization for providing the oxygen product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 illustrates an air separation plant according to an embodiment of the present invention in a simplified depiction.

[0038] FIG. 2 illustrates an air separation plant according to an embodiment of the present invention in a simplified partial depiction.

[0039] FIG. 3 illustrates an air separation plant according to an embodiment of the present invention in a simplified partial depiction.

[0040] FIG. 4 illustrates an air separation plant according to an embodiment of the present invention in a simplified partial depiction.

[0041] FIG. 5 illustrates a pressurization vaporization for an air separation plant according to an embodiment of the present invention.

[0042] In the figures, elements corresponding to one another are indicated by identical reference signs and are not explained repeatedly for the sake of clarity. If method steps are described below, these also apply to the devices used for these method steps and vice versa.

DETAILED DESCRIPTION OF THE DRAWINGS

[0043] In FIG. 1, an air separation plant according to an embodiment of the present invention is shown in the form of a schematic process flow diagram and is denoted as a whole by 100.

[0044] The air separation plant 100 is supplied with air from the atmosphere A in the form of an input air flow a via a filter 1, which air is compressed in a main air compressor 2, cooled in a post-cooler (not denoted separately) and a direct contact cooler with water W, dried and freed of carbon dioxide in an adsorber station 4, supplied to a main heat exchanger 5 at the warm side, guided in the main heat exchanger 5 nearly to the cold end, and fed into a first distillation column 11 of a distillation column system 10. The feeding takes place in part without further cooling in the form of a material flow a1, partly after cooling in a sump boiler 121 in the sump of a second distillation column 12 of the distillation column system 10.

[0045] The air separation plant 100 is designed to carry out a SPECTRA process, for which purpose two liquid material flows b and c are withdrawn from the first distillation column 11 at different positions, i.e., via a side draw and from the sump, in each case supercooled in the main heat exchanger 5, expanded, and vaporized in a heat exchanger 111 against condensing top gas of the first distillation column 11. Liquid nitrogen can, for example, be fed from a store I. The material flow b is thereafter recompressed at least in part in a compressor 6 coupled to an expansion machine 7 and a brake (not separately denoted), cooled again in the main heat exchanger 5, and fed back into the first distillation column 11. The material flow c is at least partly heated in the main heat exchanger 5, expanded in the expansion machine 7, and discharged from the air separation plant 100.

[0046] The top gas is withdrawn from the first column 11 in the form of a material flow c, which is then divided into a partial flow c1, which is conducted into the heat exchanger 111 and liquefied there, and a partial flow c2, which is discharged from the air separation plant 100 as product N1, N2. After liquefaction, the material flow c1 is partly returned to the first column 11 as a return flow. A further portion can be cooled after supercooling in a heat exchanger 8 against a part of itself and can be discharged as liquid nitrogen product C. A part can be discharged from the air separation plant 100 as a purge flow P.

[0047] The second distillation column 12 is fed with a liquid side flow d from the first distillation column 11, which is supercooled in the sump boiler 121 and then dispensed to the second distillation column 12 at the top. An oxygen product is formed by cryogenic, oxygen-rich liquid which is withdrawn from the sump of the second distillation column 12 in the form of a material flow e. After feeding in a further material flow (see below), the material flow e is supplied as liquid oxygen to a pressurization vaporization 20 (see the details below and link E in FIG. 1).

[0048] From the top of the second distillation column, impure nitrogen in the form of a material flow f is drawn off and, after combining with, inter alia, the expanded flow c, is heated in the main heat exchanger 5 and emitted to the atmosphere A and/or used as regeneration gas in the adsorber station 4.

[0049] Further treatment of the liquid oxygen of the material flow e takes place in the pressurization vaporization 20, illustrated in a greatly simplified manner. For details, reference is also made to FIG. 4. Liquid oxygen which was pressurized in the pressurization vaporization 20 is discharged to a withdrawal G in the form of a material flow g. It is also possible to subject this liquid oxygen, as illustrated with K, to a vaporization in the main heat exchanger 5 and to discharge it from the air separation plant 100. Gas which accumulates during the pressurization vaporization is either emitted to the atmosphere, as illustrated here with V, but, in an embodiment of the invention shown here, is partly guided through the sump boiler 121 and fed into the material flow e. In this way, a material utilization takes place. Heat integration in the main heat exchanger 5 can also take place, as illustrated with K.

[0050] FIGS. 2, 3, and 4 each illustrate part of an air separation plant according to an embodiment of the invention which, in addition to the components shown, can have, for example, those of the air separation plant 100 according to FIG. 1. The integration is apparent via the illustrated material flows, inter alia the material flows a2, d, e, and f. A buffer store 21 is provided in each case. This is capable of buffering the periodically accumulating amounts of gas from the pressurization vaporization 20, as explained with respect to FIG. 5, in order to feed them continuously to the utilization.

[0051] While, in the embodiment according to FIG. 2, the utilization of the material flow h substantially takes place as in the air separation plant 100 according to FIG. 1, this is not the case in the embodiment according to FIG. 3. Here, the material flow h is fed directly into the second distillation column 12. Alternatively, the thermal utilization in the heat exchanger 8, which is denoted by 8′ in FIG. 4 for better differentiability and is equipped with corresponding additional passages, is also possible. The material flow h, which is also denoted by h′ merely for better differentiability downstream of the heat exchanger 8′, can then, in particular, be fed to the material flow e.

[0052] It is understood that the features shown in FIGS. 1 through 4 can also be combined. Thus, for example, in all cases, operation with or without a buffer store 21 and with or without thermal utilization in a heat exchanger 8′ can take place. The types of utilization illustrated in FIGS. 1 through 4 can each also comprise only the use of partial flows of the material flow h, wherein further partial flows can be used in other ways.

[0053] FIG. 5 illustrates a pressurization vaporization 20 for an air separation plant according to an embodiment of the present invention in a schematic depiction. The pressurization vaporization is also denoted here by 20. The pressurization vaporization 20 can correspond in particular to the pressurization vaporization described in EP 3 193 114 A1, but also deviates therefrom. In general, in the context of the present invention, utilization of gas which is formed in a pressurization vaporization is provided for. This gas accumulates in particular after the draining, i.e., after the emptying of a tank pressurized in the pressurization vaporization, in the subsequent expansion for refilling. Therefore, the present invention is suitable for all cases of pressurization vaporization in which a corresponding emptying of tanks takes place.

[0054] An essential component of the pressurization vaporization 20 is a double-tank system, which here is denoted as 70 overall, and includes the two tanks 71 and 72. By means of a pump 55, the pressure of the cryogenic liquid of the fluid flow e, denoted here as 41, can be increased. However, the pump 55 is not absolutely necessary if the pressurization by vaporization alone is sufficient. In the case of pressurization vaporization 20, pump 55 is regularly omitted, and the cryogenic liquid of the flow 41 is fed into the tanks 71 and 72 at distillation pressure in second distillation column 12.

[0055] The tank system 70 is equipped with a pressurization vaporization device 75. In the pressurization vaporization device 75, a portion of the cryogenic liquid of the flow 41 withdrawn in liquid form from the tanks 71 or 72 is vaporized. The vaporized gas present under an increased pressure is supplied to a headspace of the tanks 71 or 72. In this way, the pump 55 can be omitted, and only a pressurization vaporization can be used. However, it becomes apparent that part of the product is converted into the gas phase in doing this. If the cryogenic liquid is withdrawn from the respective tank 71, 72, the gas phase remains. In conventional methods, this is blown off to the atmosphere, as illustrated here and previously with V. Instead, the embodiment of the invention illustrated here provides that a part in the form of material flow h be used, as explained above.

[0056] The pressure-elevated fluid flow 41 is supplied to either the tank 71 or the tank 72 and is then pressurized. In this case, the tanks 71 and 72 are alternately charged with the cryogenic liquid of the fluid flow 41, i.e., during a first time period, the cryogenic liquid of the fluid flow 41 is supplied to the first tank 71 and not to the second tank 72, and, during a second time period, to the second tank 72 and not to the first tank 71. To control correspondingly used valves 71a and 72a, a tank control 80 can be provided, for example.

[0057] Furthermore, cryogenic liquid is always withdrawn from the tank 71, 72 which is currently not being supplied with the fluid flow 41. This liquid can generally be discharged directly after withdrawal. In the embodiment shown, however, this is transferred unheated into a further tank 73. For example, when the further tank 73 is completely filled, it can also be provided, as illustrated here by means of a line 74, for corresponding fluid to be conducted onwards directly and to be supplied to heating. The heating of the fluid can, as also mentioned, take place, for example, in a main heat exchanger 5 of a corresponding air separation plant, e.g., the air separation plant 100 according to FIG. 1, and/or in an additional vaporizer 90.

[0058] However, the cryogenic liquid can also be withdrawn from the further tank 73 in the liquid state and stored in liquid state in a storage tank 76 until use. Further withdrawals upstream and/or downstream of the further tank 73 are also possible in principle.