Process and Device for Evaporating an Oxygen-Enriched Working Fluid

Abstract

A process and device for evaporating an oxygen-enriched working fluid by indirect heat exchange include introducing an oxygen-rich working fluid into the evaporation passages of an evaporator where it is partially evaporated. A first oxygen-enriched gas and a portion of the oxygen-enriched working fluid that remains liquid are drawn off from the evaporation passages. At least a part of the portion that remains liquid is returned to the evaporation passages as a circulation liquid by a conveying device. The conveying device for the circulation liquid injects a lift gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of the present invention with an evaporator arranged between two separation columns.

FIG. 2 shows a second embodiment of the present invention with an evaporator on the top of one of two separation columns that are arranged beside one another.

FIG. 3 is a schematic diagram of an evaporator.

Claims

1. A process for evaporating an oxygen-enriched working fluid by indirect heat exchange in an evaporator, comprising: introducing an oxygen-rich working fluid into evaporation passages of an evaporator;partially evaporating the oxygen-rich working fluid;drawing off a first oxygen-enriched gas and a portion of the oxygen-enriched working fluid that remains liquid from the evaporation passages;returning at least a part of the portion of the oxygen-enriched working fluid that remains liquid to the evaporation passages as a circulation liquid in a liquid cycle having an upper level and a lower level; andinjecting a lift gas into the liquid cycle via a conveying device,wherein the height differences between the lower end of the evaporation passages and the lower level are greater than the height differences between the upper level and the upper end of the evaporation passages.

2. A process according to claim 1, wherein the lift gas is formed by a second oxygen-enriched gas having an oxygen content that is at least equal to the oxygen content of the oxygen-enriched working fluid.

3. A process according to claim 1, wherein the circulation liquid is returned via a riser line to the evaporation passages, and wherein the conveying device is arranged in the lower half of the riser line.

4. A process according to claim 3, wherein the conveying device is arranged in the lower third of the riser line.

5. A process according to claim 1, wherein the circulation liquid is directed at least partially together with the working fluid into the evaporation passages.

6. A process according to claim 1, wherein the circulation liquid is conveyed by the conveying device at least in part separated from the working fluid.

7. A process according to claim 1, wherein the evaporator is designed at least partially as a falling-film evaporator.

8. A process according to claim 1, wherein the height differences between the lower end of the evaporation passages and the lower level are greater by at least a factor of 2 than the height differences between the upper level and the upper end of the evaporation passages.

9. A process according to claim 1, wherein the height differences between the lower end of the evaporation passages and the lower level are greater by at least a factor of 5 than the height differences between the upper level and the upper end of the evaporation passages.

10. A process according to claim 1, wherein the height differences between the lower end of the evaporation passages and the lower level are greater by at least a factor of 10 than the height differences between the upper level and the upper end of the evaporation passages.

11. A device for evaporating an oxygen-enriched working fluid by indirect heat exchange, comprising: an evaporator having evaporation passages for partial evaporation of an oxygen-rich working fluid;means for introducing the oxygen-rich working fluid into the evaporation passages;means for drawing off a first oxygen-enriched gas;means for returning at least a part of the portion of the oxygen-rich working fluid that remains liquid as a circulation liquid in a liquid cycle to the evaporation passages, wherein the liquid cycle has an upper level and a lower level,means for drawing off a portion of the oxygen-enriched working fluid that remains liquid from the evaporation passages; anda conveying device for the circulation liquid having means for injecting a lift gas,wherein the height differences between the lower end of the evaporation passages and the lower level are greater than the height differences between the upper level and the upper end of the evaporation passages.

12. A process for low-temperature separation of air in a distillation-column system, comprising: introducing compressed and purified charging air into a distillation-column system;recovering an oxygen-enriched working fluid in a first separation column; andsubjecting the oxygen-enriched working fluid to a process for evaporation according to claim 1.

13. A process according to claim 12, further comprising introducing a produced first oxygen-enriched gas at least in part into the first separation column.

14. A process according to claim 12, wherein the distillation-column system comprises a second separation column and an evaporator comprising a condenser-evaporator, wherein a gaseous fraction from the second separation column is introduced into liquefaction passages of the condenser-evaporator.

15. A process according to claim 14, wherein at least a portion of the liquid that is formed in the liquefaction passages is introduced into the second separation column.

16. A device for low-temperature separation of air with a distillation-column system, comprising: at least a first separation column;means for introducing compressed and purified charging air into the distillation-column system;means for recovering a liquid fraction in the first separation column;a device according to claim 11 for evaporating this liquid fraction as an oxygen-enriched working fluid.

17. A process according to claim 1, wherein the conveying device comprises a gas-lift pump.

18. A device according to claim 11, wherein the conveying device comprises a gas-lift pump.

19. A device for evaporating an oxygen-enriched working fluid by indirect heat exchange, comprising: an evaporator having evaporation passages for partial evaporation of an oxygen-rich working fluid;a line for drawing off a first oxygen-enriched gas;a line for drawing off a portion of the oxygen-enriched working fluid that remains liquid;a line for returning at least a part of the portion of the oxygen-enriched working fluid that remains liquid as a circulation liquid in a liquid cycle to the evaporation passages, wherein the liquid cycle has an upper level and a lower level; andan gas-lift pump for injecting a lift gas into the circulation liquid,wherein the height differences between the lower end of the evaporation passages and the lower level are greater than the height differences between the upper level and the upper end of the evaporation passages.