Flue gas purification process using a sorbent polymer composite material

• US 20050019240A1
• Filed: 06/19/2004
• Published: 01/27/2005
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: Gore Enterprise Holdings Incorporated
• Inventors: Wu, Xiaoqun, Lu, Xiao-Chun
• Granted Patent: US 7,442,352 B2
• Time in Patent Office: Days
• US Class Current: 423/210
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/202 Polymeric adsorbents
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: B01J 20/0266 Compounds of S
• CPC Class Codes: B01J 20/027 Compounds of F, Cl, Br, I
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/261 obtained by reactions only involving carbon to carbon unsaturated bonds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds per se C08F
• CPC Class Codes: B01J 20/28026 Particles within, immobilised, dispersed, entrapped in or on a matrix, e.g. a resin
• CPC Class Codes: B01J 20/28028 Particles immobilised within fibres or filaments
• CPC Class Codes: B01J 20/28033 Membrane, sheet, cloth, pad, lamellar or mat
• CPC Class Codes: B01J 20/28035 with more than one layer, e.g. laminates, separated sheets
• CPC Class Codes: B01J 20/28052 Several layers of identical or different sorbents stacked in a housing, e.g. in a column
• CPC Class Codes: B01J 20/2808 being less than 2 nm, i.e. micropores or nanopores
• CPC Class Codes: B01J 20/3007 Moulding, shaping or extruding
• CPC Class Codes: B01J 20/3078 Thermal treatment, e.g. calcining or pyrolizing
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3234 Inorganic material layers
• CPC Class Codes: B01J 20/3236 : containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B01J 20/3242 : Layers with a functional group, e.g. an affinity material, a ligand, a reactant or a complexing group
• CPC Class Codes: B01J 20/3285 : Coating or impregnation layers comprising different type of functional groups or interactions, e.g. different ligands in various parts of the sorbent, mixed mode, dual zone, bimodal, multimodal, ionic or hydrophobic, cationic or anionic, hydrophilic or hydrophobic

Abstract

This invention provides a process of removing sulfur oxides, mercury vapor, and fine particulate matters from industrial flue gases that contain such pollutants. The pollutants are removed by modules, which contain microporous adsorbent (i.e., sorbent) material that is held within a polymer matrix. The preferred polymers are fluoropolymers. The composite material that contains the microporous absorbent material held within a polymer matrix removes sulfur oxides by converting them into high concentration sulfuric acids. It also removes mercury vapor by chemically adsorbing the mercury into the matrix. It also removes fine particulate matters by surface filtration. The sulfuric acid that is produced inside the composite material is automatically expelled onto the external surfaces of the composite material and is drained into an acid reservoir together with the fine particulate matters which are washed from the external surfaces of the composite material by the constant dripping of the sulfuric acid along the external surfaces of the composite material.

Claims

1. A process for removing sulfur oxides, nitric oxides, Hg vapor, and fine particulate matters from a body or stream of gas comprising the following steps:

a. converting said sulfur oxides and nitric oxides into sulfuric acid and nitric acid on a sorbent material which is a part of a sorbent-polymer-composite (SPC) material;

b. collecting the converted sulfuric acid and nitric acid as droplets on the external surfaces of the SPC material until the droplets coalesce and run down or drip off of the external surfaces of the SPC material;

c. chemically adsorbing and fixing molecules of said Hg vapor in the SPC material; and

d. trapping said fine particles on the external surfaces of the SPC material.

2. The process of claim 1, wherein the SPC material is a composite material made of said sorbent material, which is either untreated or treated with at least one chemical substance that is retained in or on the sorbent material, and a polymer material comprising at least one fluoropolymer.

3. The process of claim 1, wherein the SPC material is in the form of one or more sheets that are formed by stretching the SPC material at high temperature to produce a microporous structure, further wherein the stretching ratio is from 0.1 to 500%.

4. The process of claim 3, wherein the one or more sheets of SPC material are held within a larger framework which is in contact with the body or stream of gas.

5. The process of claim 3, wherein the one or more sheets of SPC material form at least part of a bag structure through which the body or stream of gas is passed.

6. The process of claim 1, wherein the SPC material is in the form of a body that is at least partially coated or covered with a porous PTFE membrane.

7. The process of claim 1, wherein the sorbent material is an activated carbon that is either untreated or has been treated with at least one chemical substance that is retained in or on the activated carbon.

8. The process of claim 1, wherein the polymer comprises a fluoropolymer selected from the group consisting of polytetrafluoroethylene (PTFE);

polyfluoroethylene propylene (PFEP);

polyperfluoroacrylate (PPFA);

polyvinyl-lidene fluoride (PVDF);

a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV);

polychloro trifluoro ethylene (PCFE), and other copolymers or terpolymers containing at least one fluoromonomer with or without additional non-fluorinated monomers.

9. The process of claim 2, wherein the sorbent material has been treated with at least one chemical substance selected from the group consisting of:

alkaline metal iodides, organic iodide compounds, vanadium oxides, metal sulfates, elemental sulfur, sulfuric acid, oxides of iodine, chlorides of potassium, bromides of potassium, chlorides of sodium, bromides of sodium, chlorides of ammonium, bromides of ammonium, iodides of ammonium, zinc acetate and iodide coordination complexes.

13. The process of claim 1, wherein the body or stream of gas is a flue gas which is brought to a temperature of 30-100°

C. and a relative humidity of 10-95%, before contacting the SPC material, by spraying water into said body or stream of gas.

14. The process of claim 1, wherein the process also includes the use of an ozone generator.

10. A method for removing Hg vapor from a body or stream of gas comprising the steps of:

(a) contacting the body or stream of gas with a sorbent-polymer-composite material comprising;

(i) a sorbent material in the form of porous particles; and

(ii) a polymer material comprising at least one fluoropolymer or a copolymer or terpolymer containing at least one fluoromonomer, wherein the sorbent material is held within a matrix of the polymer material such that the particles of sorbent material are in contact with the polymer material; and

(b) chemically adsorbing the Hg vapor on the porous particles,

wherein the sorbent material is either untreated or has been treated with at least one chemical substance that is retained in or on the sorbent material.

11. The method of claim 10, wherein the sorbent material is activated carbon which is either untreated or has been treated with at least one chemical substance that is retained in or on the activated carbon and the polymer material is selected from the group consisting of polytetrafluoroethylene (PTFE);

polyfluoroethylene propylene (PFEP);

polyperfluoroacrylate (PPFA);

polyvinyl-lidene fluoride (PVDF);

a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV);

polychloro trifluoro ethylene (PCFE), and other copolymers or terpolymers containing at least one fluoromonomer with or without additional non-fluorinated monomers.

12. The method of claim 10, wherein the sorbent material has been chemically treated with at least one chemical substance selected from the group consisting of:

elemental sulfur, sulfuric acid, metal sulfates, oxides of iodine, chlorides of potassium, bromides of potassium, iodides of potassium, chlorides of sodium, bromides of sodium, iodides of sodium, chlorides of ammonium, bromides of ammonium, iodides of ammonium and zinc acetate.

15. A process for removing at least one pollutant from a body or stream of gas comprising the following steps:

(a) reacting said pollutant with water on a sorbent material held within a sorbent-polymer-composite material to form an acid;

(b) collecting the acid formed in step (a) as droplets on the external surfaces of the sorbent-polymer-composite material until the droplets coalesce and run down or drip off of the external surfaces of the sorbent-polymer-composite material; and

(c) collecting the droplets that have dripped off of the sorbent-polymer-composite material in a container;

wherein said sorbent material is either untreated or treated with at least one chemical substance that is retained in or on the sorbent material and said at least one pollutant is at least one substance selected from the group consisting of sulfur oxides and nitric oxides and the droplets that are collected in the container combine to form an aqueous solution containing from 10-60% by weight acid.

19. The process of claim 15, wherein the SPC material is a composite material made of:

(i) a sorbent material consisting essentially of porous particles that have been treated with at least one chemical substance that is retained in or on the porous particles; and

(ii) a polymer material comprising at least one fluoropolymer.

16. A sorbent-polymer-composite material comprising:

(a) a sorbent material in the form of porous particles; and

(b) a polymer material comprising at least one fluoropolymer or a copolymer or terpolymer containing at least one fluoromonomer;

wherein the sorbent material is held within a matrix of the polymer material such that the particles of sorbent material are in contact with the polymer material and said sorbent material is either untreated or treated with at least one chemical substance that is retained in or on the sorbent material.

17. A module comprising at least two sorbent-polymer-composite sheets held on a solid frame, wherein:

(a) the sorbent-polymer-composite sheets consist essentially of;

(i) sorbent material consisting essentially of porous particles that are either untreated or treated with at least one chemical substance that is retained in or on the porous particles; and

(ii) a polymer material comprising at least one fluoropolymer or a copolymer or a terpolymer containing at least one fluoromonomer; and

the sorbent material is held within a matrix of the polymer material such that the particles of sorbent material are in contact with the polymer material;

(b) the solid frame consists of a material that is compatible with sulfuric and nitric acid solutions; and

(c) the sorbent-polymer-composite sheets are held on the solid frame in parallel to one another with a gap between each of the sheets;

further wherein said module is stackable or designed to fit into a larger framework which can hold at least two of said modules.

18. A sorbent house comprising at least two of the modules of claim 17.

20. The module of claim 17, wherein said module contains at least three of said sorbent-polymer-composite sheets.