Wet oxidation

• US 7,332,095 B2
• Filed: 06/24/2003
• Issued: 02/19/2008
• Est. Priority Date: 06/24/2002
• Status: Active Grant

• Current Assignee: Wetox Limited
• Original Assignee: Victoria Link Limited (Victoria University)
• Inventors: Richardson, Michael James, Northcote, Peter Thomas, Johnston, James Howard
• Primary Examiner(s): Hruskoci; Peter A.
• Application Number:
  US10/518,589
• Publication Number:
  US 20050199557A1
• Time in Patent Office: 1,701 Days
• Field of Search: 210/762
• US Class Current: 210/759
• CPC Class Codes: B01B 1/005 Evaporation for physical or chemical purposes; Evaporation apparatus therefor, e.g. evaporation of liquids for gas phase reactions
• CPC Class Codes: B09C 1/08 chemically
• CPC Class Codes: C02F 1/725 by catalytic oxidation
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 11/08 Wet air oxidation
• CPC Class Codes: Y10S 210/908 Organic
• CPC Class Codes: Y10S 210/917 Color
• CPC Class Codes: Y10S 210/928 Paper mill waste, e.g. white water, black liquor treated

Abstract

An oxidation process is described which involves subjecting a feedstock which contains oxidizable material to temperature, pressure and contact with an oxidant. Excess water and volatile oxidation products, such as carbon dioxide, formic acid and acetic acid, are removed in the vapor phase. A catalyst may be employed to increase the rate of reaction. Preferred catalysts include the transition metal ions. Advantageously, the process may be operated in a continuous manner wherein the feedstock is continuously introduced into a reactor and a vapor phase containing volatile oxidation products continuously removed. The process is particularly applicable to the treatment of consumer and industrial waste.

Claims

1. A process for wet oxidation of a feedstock comprising at least one non-volatile oxidisable material, which process includes at least the steps of:

(a) continuously introducing the feedstock into a reactor;

(b) contacting the feedstock at temperature and pressure with an oxidant in the presence of a homogeneous catalyst to produce a vapour phase comprising at least some oxidation products and a liquid phase; and

(c) continuously removing at least some of the vapour phase comprising at least some oxidation products from the reactor while retaining the liquid phase in the reactor, wherein the vapour phase is removed from the reactor by flash vaporization.

2. A process as claimed in claim 1 wherein the feedstock is an aqueous liquid, solution, suspension, colloid, emulsion or other mixture.

3. A process as claimed in claim 1 wherein the feedstock comprises a slurry formed from substantially dry material to which is added an aqueous liquid.

4. A process as claimed in claim 1 wherein the oxidisable material comprises less than about 10% by weight of the feedstock.

5. A process as claimed in claim 1 wherein the oxidisable material comprises a mixture of substances.

6. A process as claimed in claim 1 wherein the oxidisable material is a waste product selected from industrial waste, consumer waste or a component thereof.

7. A process as claimed in claim 6 wherein the oxidisable material is waste selected from the group consisting of:

dairy shed waste;

pig and chicken waste;

milk processing plant waste;

milk, cheese and butter vat wash downs;

food processing waste;

waste from the wine industry and brewing industry;

food waste;

shipboard waste;

waste in environmentally sensitive locations;

waste from the wash downs and oil-traps of petroleum service stations and garages;

waste fats and proteins from the meat processing industry;

wool-scouring waste;

sewage;

medical waste;

fibre, ink and polymeric material from the deinking waste produced in the recycling of paper;

waste paper and paper products;

waste from the wood processing industry including waste wood and wood products, wood fibre, saw dust and wood treated with preservatives;

rubber waste;

plastic waste; and

tannin and colorants from wood pulping streams.

8. A process as claimed in claim 1 wherein the process is applied to the reclamation of sites contaminated by organic materials.

9. A process as claimed in claim 1 wherein the oxidisable material comprises an organic substance.

10. A process as claimed in claim 9 wherein the organic substance is selected from the group consisting of:

lipids;

proteins;

carbohydrates;

mineral oils;

vegetable oils;

waxes; and

hydrocarbons.

11. A process as claimed in claim 10 wherein the organic substance is a carbohydrate selected from starch and cellulose.

12. A process as claimed in claim 1 wherein the oxidisable material includes one or more oxidisable inorganic compounds.

13. A process as claimed in claim 1 wherein the oxidant is selected from the group consisting of:

air;

oxygen;

ozone;

peroxide; and

mixtures thereof.

14. A process as claimed in claim 1 wherein the temperature is between about 100°

C. and about 350°

C.

15. A process as claimed in claim 1 wherein the temperature is between about 190°

C. and about 300°

C.

16. A process as claimed in claim 1 wherein the temperature is between about 190°

C. and about 280°

C.

17. A process as claimed in claim 1 wherein the temperature is between about 190°

C. and about 210°

C.

18. A process as claimed in claim 1 wherein the temperature is between about 220°

C. and about 240°

C.

19. A process as claimed in claim 1 wherein the pressure is between about 0.7 MPa and about 17.2 MPa.

20. A process as claimed in claim 1 wherein the pressure is between about 1.4 MPa and about 13.0 MPa.

21. A process as claimed in claim 1 wherein the pressure is between about 2.0 MPa and about 3.5 MPa.

22. A process as claimed in claim 1 wherein the pressure is between about 2.1 MPa and about 2.9 MPa.

23. A process as claimed in claim 1 wherein the pressure is between about 2.9 MPa and about 3.4 MPa.

24. A process as claimed in claim 1 wherein the catalyst is selected from the group consisting of the transition metal ions and mixtures thereof.

25. A process as claimed in claim 1 wherein the catalyst is selected from the group consisting of:

copper (II) ions;

iron (II) ions;

manganese (II) ions; and

mixtures thereof.

26. A process as claimed in claims 1 wherein the catalyst is copper (II) ions.

27. A process as claimed in claim 1 further including the step of reducing the temperature and pressure of the vapour phase to recover at least one oxidation product.

28. A process as claimed in claim 27 wherein the oxidation product is selected from the group consisting of:

carbon dioxide;

formic acid;

acetic acid;

higher organic acids; and

mixtures thereof.

29. A process as claimed in claim 1 further comprising the step of recovering at least one non-volatile salt from the liquid phase.