Water control in non-aqueous acid gas recovery systems

Patent metadata

Field	Value
Publication number	US-2017050140-A1
Application number	US-201515118722-A
Country	US
Kind code	A1
Filing date	Feb 13, 2015
Priority date	Feb 13, 2014
Publication date	Feb 23, 2017
Grant date	—

Abstract

This invention is directed to methods and systems for controlling water in acid gas removal processes comprising the steps of a) treating the gas stream in an absorption zone with the NAS absorption liquid; b) direction the acid gas-loaded NAS absorption liquid to a regeneration zone; c) directing the regenerated NAS absorption liquid to step a); and d) controlling the first and second set of conditions.

First claim

1 . A process for regulating water content and removing acid gases from a water-containing gas stream using a non-aqueous solvent (NAS) absorption liquid which comprises:
(a) treating the gas stream in an absorption zone with the NAS absorption liquid under a first set of controlled conditions of temperature, pressure and flow rate to obtain an acid gas-depleted treated gas stream and an acid gas-loaded NAS absorption liquid; (b) directing the acid gas-loaded NAS absorption liquid to a regeneration zone under a second set of controlled conditions of temperature, pressure and flow rate and regenerating the loaded NAS absorption liquid to expel a portion of the acid gases and obtain a regenerated NAS absorption liquid; (c) directing the regenerated NAS absorption liquid to step a); and (d) controlling the first and second set of conditions so as to avoid the necessity of a separation device to separate a water-rich phase from the NAS absorption liquid, to regulate the water content, and remove acid gases from the water-rich gas stream.

2 . The process of claim 1 , wherein the acid gas is carbon dioxide.

3 . The process of claim 1 , wherein the water-containing gas stream is from a desulfurization pre-treatment process.

4 . The process of claim 1 , wherein the water content is regulated such that the quantity of water entering the process in the water-rich gas stream balances the water content leaving the process in the acid gas-depleted treated gas stream or off gases from the regeneration zone.

5 . The process of claim 1 , wherein the water content is regulated such that the quantity of water entering the process in the water-rich gas stream is greater than the water content leaving the process in the acid gas-depleted treated gas stream or off gases from the regeneration zone and water is accumulated in the process.

6 . The process of claim 1 , wherein the water content is regulated such that the quantity of water entering the process in the water-rich gas stream is less than the water content leaving the process in the acid gas-depleted treated gas stream or off gases from the regeneration zone and water is depleted in the process.

7 . The process of claim 1 , wherein the gas stream is a flue gas from the combustion of a fossil fuel.

8 . The process of claim 1 , wherein the gas stream is an exhaust gas from a combustion process.

9 . The process of claim 1 , wherein the gas stream is an exhaust gas from a cement plant.

10 . The process of claim 1 , wherein regenerating the loaded NAS absorption liquid occurs by pressure release, heating, stripping or a combination thereof.

11 . The process of claim 1 , wherein the loaded NAS absorption liquid is preheated by indirect heat exchange with the regenerated absorption liquid.

12 . The process of claim 1 , wherein the NAS absorption liquid comprises a nitrogenous base; a weak acid having pKa between 8-15; and a hydrophobic, aliphatic diluent or a polyether diluent; or combination thereof.

13 . The process of claim 1 , wherein the NAS absorption liquid comprises a nitrogenous base having a nitrogen with a hydrogen atom leaving group, a weak acid, and a hydrophobic diluent.

14 . The solvent system of claim 1 , wherein the solvent system is immiscible with water.

15 . The solvent system of claim 1 , wherein the solvent system has a solubility with water of less than about 10 g of water per 100 g of NAS.

16 . The process of claim 11 , wherein the nitrogenous base is an amine, an amidine, a guanidine, or a combination thereof.

17 . The process of claim 11 , wherein the weak acid is a fluorinated alcohol, a phenol, a substituted phenol, or a combination thereof.

18 . The process of claim 12 , wherein the nitrogenous base is 2-fluorophenylethylamine or N-methylbenzylamine; the weak acid is aniline, octafluoropentanol, phenol, substituted phenol; and the polyether diluent is a substituted ether of polyethylene glycol, a substituted ether of polypropylene glycol, or a mixture thereof.

19 . A process for regulating water content and removing acid gases from a water-containing gas stream using a non-aqueous solvent (NAS) absorption liquid which comprises:
(a) treating the gas stream in an absorption zone with the NAS absorption liquid under a first set of controlled conditions of temperature, pressure and flow rate to obtain an acid gas-depleted treated gas stream and an acid gas-loaded NAS absorption liquid; (b) directing the acid gas-loaded NAS absorption liquid to a regeneration zone under a second set of controlled conditions of temperature, pressure and flow rate and regenerating the loaded NAS absorption liquid to expel a portion of the acid gases and obtain a regenerated NAS absorption liquid; (c) directing the regenerated NAS absorption liquid to step a); and (d) controlling the first and second set of conditions so as to (i) balance the water content entering the process in the water-rich gas stream with the water content leaving the process; (ii) accumulate water from the water-rich gas stream; or (iii) deplete water from water-rich gas stream; and (e) remove acid gases from the water-rich gas stream.

20 . An acid gas recovery system using a non-aqueous solvent (NAS) absorption liquid which comprises:
(a) an absorption unit for treating a water-rich gas stream with an absorption zone containing the NAS absorption liquid under a first set of controlled conditions of temperature, pressure and flow rate which forms an acid gas-depleted treated gas stream and an acid gas-loaded NAS absorption liquid; (b) a regeneration unit with a regeneration zone in fluid communication with the acid gas-loaded NAS absorption liquid under a second set of controlled conditions of temperature, pressure and flow rate and regenerating the loaded NAS absorption liquid to expel a portion of the acid gases and to form a regenerated NAS absorption liquid; (c) a means to return the regenerated NAS absorption liquid to the absorption unit in step (a); and (d) a controller for the first and second set of conditions so to avoid the necessity of a separation device to separate a water-rich phase from the NAS absorption liquid, to regulate the water content, and remove acid gases from the water-rich gas stream.

21 . The system of claim 20 , wherein the acid gas is carbon dioxide.

22 . The system of claim 20 , wherein the water-rich gas stream is from a desulfurization pre-treatment process.

23 . The system of claim 20 , wherein the water-rich gas stream is a flue gas from the combustion of a fossil fuel.

24 . The system of claim 20 , wherein the water-rich gas stream is an exhaust gas from a combustion process.

25 - 34 . (canceled)

Assignees

• Res Triangle Inst

Inventors

• Coleman Luke
• Lail Marty
• Amato Kelly E
• Tanthana Jak

Classifications

• B01D53/1425

  Regeneration of liquid absorbents · CPC title

• B01D2252/20405

  Monoamines · CPC title

• B01D2252/30

  Ionic liquids and zwitter-ions · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title

• B01D2252/204

  Amines · CPC title