Method for recovering energy

Patent metadata

Field	Value
Publication number	US-9976569-B2
Application number	US-201013575143-A
Country	US
Kind code	B2
Filing date	Dec 27, 2010
Priority date	Jan 25, 2010
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

Method for recovering energy when compressing a gas using a compressor system with two or more compression stages, with each stage having a compressor element. Downstream from at least two compressor elements there is a heat exchanger having a primary and a secondary part. The coolant is guided successively in series through the secondary part of at least two heat exchangers, and the guiding sequence is chosen such that the temperature at the inlet of the primary part of at least one subsequent heat exchanger is higher than or equal to the temperature at the inlet of the primary part of a preceding heat exchanger, relative to the direction of flow of the coolant. At least one heat exchanger is provided with a tertiary part for a coolant.

First claim

The invention claimed is:

1. A method for recovering energy when compressing a gas using a compressor having two or more compression stages, with each stage including a compressor element, wherein downstream from each of at least two of said compressor elements there is a heat exchanger, comprising the steps:
guiding compressed gas from a first compression stage upstream from a first heat exchanger through a primary part of the first heat exchanger and guiding the compressed gas from the primary part of the first heat exchanger to a second compression stage and through a primary part of a second heat exchanger;
guiding a coolant to recover part of the compression heat from the compressed gas successively in series through a secondary part of the first heat exchanger and through a secondary part of the second heat exchanger;
selecting the sequence in which the coolant is guided in series through the first heat exchanger and the second heat exchanger so that the temperature at an inlet of the primary part of the first heat exchanger is higher than or equal to the temperature at an inlet of the primary part of the second heat exchanger; and
providing at least one of the first heat exchanger and the second heat exchanger with a tertiary part for the coolant or another coolant.

2. The method according to claim 1 , wherein the second heat exchanger is the last heat exchanger through which the coolant is guided.

3. The method according to claim 1 , wherein the steps are carried out such that there is a minimal impact on the overall efficiency of the compressor by attuning the sequence with which the coolant is guided through the different heat exchangers to the impact of the sequence on the different inlet temperatures of the stages and their accompanying effect on total system efficiency.

4. The method according to claim 1 , wherein the sequence in which the coolant is guided through the first heat exchanger and the second heat exchanger is selected such that, between two successive heat exchangers in the sequence of the first and the second heat exchangers, the coolant first flows through one of the heat exchangers in which the gas flows through the primary part of the compressor element with a lowest cooling power uptake.

5. The method according to claim 1 , wherein the coolant is guided sequentially through all heat exchangers of the compressor.

6. The method according to claim 1 , wherein, the coolant first flows through the secondary part of the heat exchanger with the tertiary part, then through the other heat exchangers, and finally through the tertiary part of the heat exchanger with the tertiary part.

7. The method according to claim 1 , wherein when the gas is compressed in three stages, the compressor further comprises a third compression stage and a third heat exchanger, wherein the compressor has a low-pressure stage, a first high-pressure stage and a second high-pressure stage, wherein the low-pressure stage comprises the first heat exchanger, the first high-pressure stage comprises the second heat exchanger, and the second high-pressure stage comprises the third heat exchanger, so that the coolant is guided successively through the first, second, third heat exchangers and finally back through the first heat exchanger.

8. The method according to claim 1 , wherein before flowing through the different heat exchangers, the coolant is used to cool one or more motors driving the compressor elements and/or their respective motor controls.

9. The method according to claim 1 , wherein a second coolant flows through the tertiary part.

10. The method according to claim 9 , wherein the second coolant is also used to cool one or more motors driving the compressor elements and/or their respective motor controls.

11. The method according to claim 1 , further comprising the step of controlling a rotational speed of one or more compressor elements.

12. The method according to claim 11 , wherein rotational speeds of the compression stages are controlled in order to at least partly change at least a pressure or temperature of each compressor stage-operating region.

13. The method according to claim 11 , wherein the relative rotational speeds of the compression stages are changed in proportion to a change of a respective inlet temperature of the compression stage.

14. The method according to claim 1 , wherein tube type heat exchangers are used, said heat exchangers comprising tubes in a housing with an input and output for a first medium that is caused to flow through the tubes and an input and an output for a second medium that is caused to flow around the tubes, and wherein the coolant is caused to flow through the tubes and the gas is caused to flow around the tubes.

15. The method according to claim 1 , further comprising a third heat exchanger.

16. A method for recovering energy when compressing a gas using a compressor having two or more compression stages, with each stage including a compressor element, wherein downstream from each of at least two of said compressor elements there is a heat exchanger, comprising the steps:
guiding compressed gas from a first compression stage upstream from a first heat exchanger through a primary part of the first heat exchanger and guiding the compressed gas from the primary part of the first heat exchanger to a second compression stage and through a primary part of a second heat exchanger and guiding the compressed gas from the primary part of the second heat exchanger to a third compression stage and through a primary part of a third heat exchanger;
guiding a coolant to recover part of the compression heat from the compressed gas successively in series through a secondary part of the first heat exchanger and through a secondary part of the second heat exchanger;
selecting the sequence in which the coolant is guided in series through the first heat exchanger and the second heat exchanger so that the temperature at an inlet of the primary part of the first heat exchanger is higher than or equal to the temperature at an inlet of the primary part of the second heat exchanger; and
providing at least one of the first heat exchanger and the second heat exchanger with a tertiary part for the coolant or another coolant,
wherein the compressor has a low-pressure stage, a first high-pressure stage and a second high-pressure stage, where the low-pressure stage comprises the first heat exchanger, the first high-pressure stage comprises the second heat exchanger, and the second high-pressure stage comprises the third heat exchanger, so that the coolant first flows through the second heat exchanger, then through the third heat exchanger and finally through the first heat exchanger.

17. The method according to claim 16 , wherein the compressor elements of the first and second high-pressure stages are driven by a common drive whose rotational speed is controlled independently from a drive for the compressor element of the low-pressure stage.

18. The method according to claim 16 , wherein the first heat exchanger comprises the heat exchanger with the tertiary part.

19. A method for recovering energy when compressing a gas using a compressor having at least three compression stages, with each stage including a compressor element, wherein downstream from each compressor element there is a heat exchanger, comprising the steps:
guiding compressed gas from a low-pressure stage upstream from a first heat exchanger through a primary part of the first heat exchanger and guiding a coolant to recover part of the compression heat from the co

Assignees

• Janssens Stijn Jozef Rita Johanna
• Atlas Copco Airpower Nv

Inventors

• Janssens Stijn Jozef Rita Johanna

Classifications

• F25J3/04018

  of main feed air · CPC title

• F25J2230/04

  Compressor cooling arrangement, e.g. inter- or after-stage cooling or condensate removal · CPC title

• F25J2205/04

  in the feed line, i.e. upstream of the fractionation step · CPC title

• F28D21/0001

  Recuperative heat exchangers · CPC title

• F04C29/04

  Heating; Cooling (of machines or engines in general F01P); Heat insulation (heat insulation in general F16L59/00) · CPC title