Method for dehumidifying humid gas mixtures using ionic liquids

• US 10,500,540 B2
• Filed: 06/28/2016
• Issued: 12/10/2019
• Est. Priority Date: 07/08/2015
• Status: Active Grant

• Current Assignee: Evonik Operations GmbH (Rag-Stiftung)
• Original Assignee: Evonik Degussa GmbH (Rag-Stiftung)
• Inventors: Zehnacker, Olivier, Wang, Xinming, Willy, Benjamin, Schneider, Rolf, Schneider, Marc-Christoph
• Primary Examiner(s): Lawrence, Jr., Frank M
• Application Number:
  US15/742,436
• Publication Number:
  US 20180169572A1
• Time in Patent Office: 1,260 Days
• Field of Search: 95149, 95156, 95178, 95179, 95180, 95187, 95231, 96272, 96322, 34 80, 34472, 34473, 62114
• CPC Class Codes: B01D 2252/30 Ionic liquids and zwitter-ions
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/4508 for cleaning air in buildings
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/263 by absorption
• CPC Class Codes: B01D 53/28 Selection of materials for use as drying agents
• CPC Class Codes: C09K 5/047 for absorption-type refrigeration systems
• CPC Class Codes: F24F 3/1417 with liquid hygroscopic desiccants
• CPC Class Codes: F25B 15/02 without inert gas F25B15/004, F25B15/006, F25B15/008, F25B15/12, F25B15/14, F25B15/16 take precedence
• CPC Class Codes: F25B 15/06 the refrigerant being water vapour evaporated from a salt solution, e.g. lithium bromide F25B15/025 takes precedence
• CPC Class Codes: F25B 30/04 of the sorption type

Abstract

The invention relates to a process for dehumidifying a moist gas mixture. The invention further relates to an apparatus for dehumidifying a moist gas mixture and to the use of said apparatus in the process according to the invention.

Claims

1. A process for dehumidifying a moist gas mixture G in an apparatus V₁, comprising the steps of:

(a) contacting the moist gas mixture G with a liquid absorption medium A_VE comprising at least one salt selected from the group consisting of;

Q⁺(RO)₂PO₂⁻

;

(Q⁺)₂ROPO₃²⁻

; and

Q⁺M⁺ROPO₃²⁻

;

wherein the liquid absorption medium A_VE at least partially absorbs water from the moist gas mixture G, to obtain a liquid absorption medium A_VE1 having an elevated water content compared to the liquid absorption medium A_VE and a gas mixture G₁ having a relatively low water content compared to the moist gas mixture G;

(b) at least partially removing water from the liquid absorption medium A_VE1 to obtain a liquid absorption medium A_VE2 having a relatively low water content compared to the liquid absorption medium A_VE1;

wherein the apparatus V₁ at least partially comprises a surface made of an aluminium material of construction O_Al and in the apparatus V₁, at least one of the liquid absorption media selected from the group consisting of A_VE, A_VE1, A_VE2 contacts the surface made of O_Al via at least one contact surface;

and wherein;

Q⁺ is a 1,3-dialkylimidazolium in which the alkyl groups are, independently of one another, unbranched or branched C₁-C₆ alkyl groups;

R is an unbranched or branched C₂-C₆ alkyl group;

and M⁺ is an alkali metal ion.

2. The process of claim 1, wherein R is selected from the group consisting of:

an ethyl group and a n-butyl group.

3. The process of claim 1, wherein Q⁺ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium.

4. The process of claim 3, wherein the salt is selected from the group consisting of:

1,3-diethylimidazolium diethylphosphate;

1-ethyl-3-methylimidazolium diethylphosphate; and

1-n-butyl-3-methylimidazolium di-n-butylphosphate.

5. The process of claim 1, wherein the liquid absorption medium A_VE is an aqueous solution in which the total weight of all salts of structure Q⁺(RO)₂PO₂⁻

, (Q⁺)₂ROPO₃²⁻

and Q⁺M⁺ROPO₃²⁻

is at least 70 wt % based on the total weight of the aqueous solution.

6. The process of claim 1, wherein said process is carried out in continuous fashion.

7. The process of claim 2, wherein:

a) Q⁺ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and

b) the liquid absorption medium A_VE is an aqueous solution in which the total weight of all salts of structure Q⁺(RO)₂PO₂⁻

, (Q⁺)₂ROPO₃²⁻

and Q⁺M⁺ROPO₃²⁻

is at least 70 wt % based on the total weight of the aqueous solution.

8. The process of claim 1, wherein said process is carried out using an apparatus V₂ for dehumidifying a moist gas mixture, wherein said apparatus comprises the components:

a) a liquid absorption medium A_VO comprising at least one salt selected from the group consisting of;

Q⁺(RO)₂PO₂⁻

;

(Q⁺)₂ROPO₃²⁻

; and

Q⁺M⁺ROPO₃²⁻

;

b) at least one water absorption unit W_abs2 for contacting the moist gas mixture with the liquid absorption medium A_VO;

c) at least one water desorption unit W_des2 which comprises a heat exchanger W_x2 and is set up for at least partially removing water from a liquid absorption medium A_VO; and

d) a circuit U₂ which connects the water absorption unit W_abs2 with the water desorption unit W_des2 and by means of which the liquid absorption medium A_VO may be circulated;

wherein at least one of the components W_abs2, W_des2, and U₂ at least partially comprises a surface made of an aluminium material of construction O_Al; and

wherein disposed in the apparatus V₂ is at least one contact surface at which the liquid absorption medium A_VO contacts the surface made of O_Al;

and wherein;

Q⁺ is a 1,3-dialkylimidazolium where the alkyl groups are independently of one another unbranched or branched C₁-C₆ alkyl groups;

R is an unbranched or branched C₂-C₆ alkyl group;

and M⁺ is an alkali metal ion.

9. The process of claim 8, wherein R is selected from the group consisting of:

an ethyl group and a n-butyl group.

10. The process of claim 9, wherein:

a) Q⁺ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and

b) the liquid absorption medium A_VE is an aqueous solution in which the total weight of all salts of structure Q⁺(RO)₂PO₂⁻

, (Q⁺)₂ROPO₃²⁻

and Q⁺M⁺ROPO₃²⁻

is at least 70 wt % based on the total weight of the aqueous solution.

11. An apparatus V₂ for dehumidifying a moist gas mixture, comprising the components:

a) a liquid absorption medium A_VO comprising at least one salt selected from the group consisting of;

Q⁺(RO)₂PO₂⁻

;

(Q⁺)₂ROPO₃²⁻

; and

Q⁺M⁺ROPO₃²⁻

;

b) at least one water absorption unit W_abs2 for contacting the moist gas mixture with the liquid absorption medium A_VO;

c) at least one water desorption unit W_des2 which comprises a heat exchanger W_x2 and is set up for at least partially removing water from a liquid absorption medium A_VO; and

d) a circuit U₂ which connects the water absorption unit W_abs2 with the water desorption unit W_des2 and by means of which the liquid absorption medium A_VO may be circulated;

wherein at least one of the components W_abs2, W_des2, and U₂ at least partially comprises a surface made of an aluminium material of construction O_Al; and

wherein disposed in the apparatus V₂ is at least one contact surface at which the liquid absorption medium A_VO contacts the surface made of O_Al;

and wherein;

Q⁺ is a 1,3-dialkylimidazolium where the alkyl groups are independently of one another unbranched or branched C₁-C₆ alkyl groups;

R is an unbranched or branched C₂-C₆ alkyl group;

and M⁺ is an alkali metal ion.

12. The apparatus V₂ of claim 11, wherein R is selected from the group consisting of:

an ethyl group and a n-butyl group.

13. The apparatus V₂ of claim 11, wherein Q⁺ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium.

14. The apparatus V₂ of claim 13, wherein the salt is selected from the group consisting of:

1,3-diethylimidazolium diethylphosphate;

1-ethyl-3-methylimidazolium diethylphosphate; and

1-n-butyl-3-methylimidazolium di-n-butylphosphate.

15. The apparatus V₂ of claim 11, wherein A_VO is an aqueous solution in which the total weight of all salts of structure Q⁺(RO)₂PO₂⁻

, (Q⁺)₂ROPO₃²⁻

and Q⁺M⁺ROPO₃² is at least 70 wt % based on the total weight of the aqueous solution.

16. The apparatus V₂ of claim 11, wherein at least one of the components W_abs2, and W_des2 is a falling film.

17. The apparatus V₂ of claim 11, comprising a further heat exchanger W_y2 positioned so that liquid absorption medium A_VO sent from the water absorption unit W_abs2 to the water desorption unit W_des2 is suppliable with heat from liquid absorption medium A_VO, said medium being conducted away from the water desorption unit W_des2.

18. The apparatus of claim 12, wherein:

a) Q⁺ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and

b) the liquid absorption medium A_VE is an aqueous solution in which the total weight of all salts of structure Q⁺(RO)₂PO₂⁻

, (Q⁺)₂ROPO₃²⁻

and Q⁺M⁺ROPO₃² is at least 70 wt % based on the total weight of the aqueous solution.

19. The apparatus of claim 18, comprising a further heat exchanger W_y2 positioned so that liquid absorption medium A_VO sent from the water absorption unit W_abs2 to the water desorption unit W_des2 is suppliable with heat from liquid absorption medium A_VO, said medium being conducted away from the water desorption unit W_des2.

20. An absorption heat pump, comprising the apparatus V₂ of claim 11, as further components, a condenser, an evaporator and a coolant, wherein the coolant is water.