Process for dehumidifying moist gas mixtures

• US 10,493,400 B2
• Filed: 06/12/2017
• Issued: 12/03/2019
• Est. Priority Date: 06/14/2016
• Status: Active Grant

• Current Assignee: Evonik Operations GmbH (Rag-Stiftung)
• Original Assignee: Evonik Degussa GmbH
• Inventors: Irfan, Muhammad, Rolker, Jorn, Schneider, Rolf
• Primary Examiner(s): Louie, Philip Y
• Application Number:
  US15/619,561
• Publication Number:
  US 20170354924A1
• Time in Patent Office: 904 Days
• Field of Search: None
• CPC Class Codes: B01D 2252/2026 Polyethylene glycol, ethers or esters thereof, e.g. Selexol
• CPC Class Codes: B01D 2252/20473 containing an imidazole-ring
• CPC Class Codes: B01D 2252/30 Ionic liquids and zwitter-ions
• CPC Class Codes: B01D 2252/61 Antifouling agents
• CPC Class Codes: B01D 2259/4508 for cleaning air in buildings
• 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: F24F 3/1417 with liquid hygroscopic desiccants
• CPC Class Codes: F25B 15/00 Sorption machines, plants or systems, operating continuously, e.g. absorption type
• 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 2339/047 Water-cooled condensers
• CPC Class Codes: F25B 30/04 of the sorption type
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

The invention relates to a process for dehumidifying a moist gas mixture and to the absorption medium used in the process. 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 dehumidifing a moist gas mixture G₁, wherein the moist gas mixture G₁ comprises CO₂, said process comprising:

contacting the moist gas mixture G₁ with a liquid absorption medium A₁, wherein A₁ comprises a mixture of triethylene glycol and at least one salt S selected from the group consisting of;

Q⁺A⁻

;

to obtain a gas mixture G₂, which has a lower water content compared to moist gas mixture G₁, and a liquid absorption medium A₂, which has an elevated water content compared to the liquid absorption medium A₁;

, wherein;

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

b) A⁻

is an anion selected from the group consisting of acetate and propionate.

2. The process of claim 1, wherein the liquid absorption medium A₁ is an aqueous solution in which the total weight of triethylene glycol and all salts S is at least 70 wt % based on the total weight of the aqueous solution.

3. The process of claim 1, wherein, in the liquid absorption medium A₁, the ratio of the weight of the triethylene glycol to the total weight of all salts S is in the range 1:

9 to 9;

1.

4. The process of claim 1, wherein the proportion of CO₂ in the moist gas mixture G₁ is in the range 1 ppm to 140000 ppm.

5. An absorption medium consisting of a mixture of triethylene glycol and at least one salt S selected from the group consisting of:

Q⁺A⁻

, wherein;

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

b) A⁻

is an anion selected from the group consisting of acetate and propionate.

6. The absorption medium of claim 5, wherein said absorption medium is an aqueous solution in which the total weight of triethylene glycol and all salts S is at least 70 wt % based on the total weight of the aqueous solution.

7. The absorption medium of claim 5, wherein the ratio of the weight of the triethylene glycol to the total weight of all salts S is in the range 1:

9 to 9;

1.