Claims
- 1. A process for regenerating a sulfur capturing additive used in the preparation of a hydrocarbon in water emulsion for combustion as a fuel comprising:
- (a) forming a hydrocarbon in water emulsion by admixing a sulfur containing hydrocarbon and water with an emulsifier and a water soluble sulfur capturing additive wherein said sulfur capturing additive is selected from the group consisting of Na.sup.+, K.sup.+, Li.sup.+, Ca.sup.++, Ba.sup.++, Mg.sup.++, Fe.sup.+++ and mixtures thereof;
- (b) burning said emulsion so as to form a combustion ash containing said water soluble additive as a sulfate compound;
- (c) leaching said combustion ash wherein said combustion ash is leached with water in a water to ash ratio in ml to grams of 1:1 to 30:1 so as to dissolve said water soluble additive sulfate compound to form a pregnant leach liquor containing said additive;
- (d) separating said pregnant leach liquor containing said additive;
- (e) adjusting said pregnant leach liquor with a base precipitating agent wherein said base precipitating agent is selected from the group consisting of NH.sub.4 OH, NaOH, Ca(OH).sub.2, NaCO.sub.3 and mixtures thereof wherein said pregnant leach liquor is adjusted with said base to a pH of greater than 7 so as to precipitate an additive compound; and
- (f) recovering said additive compound.
- 2. A process according to claim 1 including the step of:
- (g) recycling and admixing said additive compound with said hydrocarbon in water emulsion prior to combustion of same as a fuel.
- 3. A process according to claim 1 wherein said additive compound is a hydroxide.
- 4. A process according to claim 3 including the step of:
- (g) mixing said additive hydroxide compound with water and carbon dioxide so as to form an additive carbonate compound.
- 5. A process according to claim 4 including the step of:
- (h) recycling and admixing said additive carbonate compound with said hydrocarbon in water emulsion prior to combustion of same as a fuel.
- 6. A process according to claim 1 wherein said hydrocarbon contains metals which are separated from said pregnant leach liquor in step (c) as a solid residue.
- 7. A process according to claim 6 including the steps of:
- (g) mixing said solid residue with an acid solution so as to dissolve said metals; and
- (h) precipitating said metals by adjusting the pH of said acid solution to between 2 to 6.
- 8. A process according to claim 7 including the steps of:
- (i) adjusting the pH to about 2; and
- (j) thereafter adjusting the pH to between 5 and 6.
- 9. A process according to claim 1 including the step of:
- (g) recovering ammonium sulfate from step (e) via crystallization.
- 10. A process according to claim 1 wherein said combustion ash is leached with water in a water to ash ratio in ml to grams of 2:1 to 10:1.
- 11. A process according to claim 1 wherein said combustion ash is leached at a temperature of 5.degree. to 200.degree. C.
- 12. A process according to claim 10 wherein said combustion ash is leached at a temperature of 15.degree. to 95.degree. C.
- 13. A process according to claim 11 wherein said combustion ash is leached for between 0.1 to 5 hours.
- 14. A process according to claim 13 wherein said combustion ash is leached for between 0.2 to 3 hours.
- 15. A process according to claim 1 wherein said pregnant leach liquor is adjusted with said base to a pH of between 9 to 11.
- 16. A process according to claim 1 wherein said additive compound is precipitated at a temperature of 5.degree. to 95.degree. C.
- 17. A process according to claim 1 wherein said additive compound is precipitated at a temperature of 25.degree. to 80.degree. C.
- 18. A process according to claim 4 wherein said carbon dioxide is added to said additive hydroxide compound in a closed vessel at a temperature of 0.degree. to 150.degree. C. at a CO.sub.2 partial pressure of up to 1000 psi.
- 19. A process according to claim 4 wherein said carbon dioxide is added to said additive hydroxide compound in a closed vessel at a temperature of 3.degree. to 95.degree. C. at a CO.sub.2 partial pressure of 1 to 500 psi.
- 20. A process according to claim 18 including agitating said closed vessel.
- 21. A process according to claim 19 including agitating said closed vessel.
- 22. A process according to claim 7 wherein said acid solution is a 2 to 30% sulfuric acid solution and is added in a solution to solid residue ratio in ml to grams of 1:1 to 30:1.
- 23. A process according to claim 7 wherein said acid solution is a 2 to 30% sulfuric acid solution and is added in a solution to solid residue ratio in ml to grams of 2:1 to 10:1.
- 24. A process according to claim 22 including the steps of:
- (i) adjusting the pH to about 2; and
- (j) thereafter adjusting the pH to between 5 and 6.
- 25. A process according to claim 23 including the steps of:
- (i) adjusting the pH to about 2; and
- (j) thereafter adjusting the pH to between 5 and 6.
- 26. A process for recovering a sulfur capturing additive from a combustion ash comprising:
- (a) leaching said combustion ash wherein said combustion ash is leached with water in a water to ash ratio in ml to grams of 1:1 to 30:1 so as to dissolve said sulfur capturing additive to form a pregnant leach liquor containing said additive wherein said sulfur capturing additive is selected from the group consisting of Na.sup.+, K.sup.+, LI.sup.+, Ca.sup.++, Ba.sup.++, Mg.sup.++, Fe.sup.+++ and mixtures thereof;
- (b) separating said pregnant leach liquor containing said additive;
- (c) adjusting said pregnant leach liquor with a base precipitating agent wherein said base precipitating agent is selected from the group consisting of NH.sub.4 OH, Na.sup.OH, Ca(OH).sub.2, NaCO.sub.3 and mixtures thereof wherein said pregnant leach liquor is adjusted with said base to a pH of greater than 7 so as to precipitate an additive compound; and
- (d) recovering said additive compound.
- 27. A process according to claim 26 wherein said additive compound is a hydroxide.
- 28. A process according to claim 27 including the step of:
- (g) mixing said additive hydroxide compound with water and carbon dioxide so as to form an additive carbonate compound.
- 29. A process according to claim 27 wherein said additive compound is ammonium hydroxide.
- 30. A process according to claim 29 including the step of:
- (g) recovering ammonium sulfate from step (e) via crystallization.
- 31. A process according to claim 26 wherein said pregnant leach liquor is adjusted with said base to a pH of between 9 to 11.
- 32. A process according to claim 28 wherein said carbon dioxide is added to said additive hydroxide compound in a closed vessel at a temperature of 0.degree. to 150.degree. C. at a CO.sub.2 partial pressure of up to 1000 psi.
- 33. A process according to claim 28 wherein said carbon dioxide is added to said additive hydroxide compound in a closed vessel at a temperature of 3.degree. to 95.degree. C. at a CO.sub.2 partial pressure of 1 to 500 psi.
- 34. A process according to claim 32 including agitating said closed vessel.
- 35. A process according to claim 33 including agitating said closed vessel.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to application Ser. No. 133,323, filed concurrently herewith and is a continuation-in-part of Application Ser. No. 014,871, filed Feb. 17, 1987 which in turn is a continuation-in-part of application Ser. No. 875,450, filed June 17, 1986.
The present invention relates to a process for the regeneration of a sulfur capturing additive used in the preparation of hydrocarbon fuels and hydrocarbon in water emulsions for combustion as fuels and, more particularly, hydrocarbon in water emulsions wherein the hydrocarbon is a low gravity, viscous hydrocarbon characterized by high sulfur and metals contents.
Low gravity, viscous hydrocarbons found in Canada, The Soviet Union, United States, China and Venezuela are normally liquid with viscosities ranging from 10,000 to 200,000 CP and API gravities of less than 12. These hydrocarbons are currently produced either by mechanical pumping, steam injection or by mining techniques. Wide-spread use of these materials as fuels is precluded for a number of reasons which include difficulty in production, transportation and handling of the material and, more importantly, unfavorable combustion characteristics including high sulfur oxide emissions and unburned solids. To date, there are two commercial processes practiced by power plants to reduce sulfur oxide emissions. The first process is furnace limestone injection wherein limestone injected into the furnace reacts with the sulfur oxides to form solid sulfate particles which are removed from the flue gas by conventional particulate control devices. The cost for burning a typical high sulfur fuel by the limestone injection method is between two to three dollars per barrel and the amount of sulfur oxides removed by the method is in the neighborhood of 50%. A more effective process for removing sulfur oxides from power plants comprises flue gas desulfurization wherein CaO+H.sub.2 O are mixed with the flue gases from the furnace. In this process 90% of the sulfur oxides are removed; however, the cost for burning a barrel of fuel using the process is between four and five Dollars per barrel. Because of the foregoing, the high sulfur content, viscous hydrocarbons have not been successfully used on a commercial basis as fuels due to the high costs associated with their burning.
It is well known in the prior art to form oil in water emulsions for use as a combustible fuel. See for example U.S. Pat. Nos. 4,114,015; 4,378,230 and 4,618,348. In addition to the foregoing, the prior art teaches that oil in water emulsions formed from low gravity, viscous hydrocarbons can likewise be successfully combusted as a fuel. See for example British Patent Specification No. 974,042 and U.S. Pat. No. 4,618,348. The assignee of the instant application has discovered that sulfur-oxide emissions can be controlled when burning viscous high sulfur containing hydrocarbon in water emulsions by the addition of sulfur capturing additives to the emulsion composition. See U.S. application Ser. Nos. 875,450; 014,871 and 133,323.
Naturally, it would be highly desirable to be able to regenerate the sulfur capturing additive in order to reduce costs and increase the overall efficiency when burning oil in water emulsions.
Accordingly, it is the principle object of the present invention to provide a process for regenerating a sulfur capturing additive used in the preparation of hydrocarbon fuels for combustion, particularly, a hydrocarbon in water emulsion for combustion as a fuel.
It is a particular object of the present invention to provide a process wherein the regenerated sulfur capturing additive is recycled for further hydrocarbon in water emulsion admixing.
It is a further object of the present invention to provide a process as set forth above wherein useful by products are generated.
Further objects and advantages of the present invention will appear hereinbelow.
In accordance with the present invention the foregoing objects and advantages are readily obtained.
The present invention relates to a process for the regeneration of a sulfur capturing additive used in the preparation of hydrocarbon fuels, particularly, hydrocarbon in water emulsions for combustion as fuels and, more particularly, hydrocarbon in water emulsions wherein the hydrocarbon is a low gravity, viscous hydrocarbon characterized by high sulfur and metals contents. The process comprises leaching a combustion ash with water so as to dissolve same and form a pregnant leach liquor containing the additive which is separated from the solid residue. The pregnant leach liquor is thereafter adjusted with a base precipitating agent so as to precipitate a compound of the additive which is then recovered by liquid solid separation. The process of the present invention is particularly useful for regenerating said recycling sulfur capturing additives used in hydrocarbon formulations which are burned as fuels, particularly, hydrocarbon in water emulsions formed from viscous hydrocarbon materials characterized by high sulfur and metals contents. Other useful by products are recoverable from the process of the present invention thereby adding to the overall efficiency and economy of same.
US Referenced Citations (10)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 0013420 |
Jan 1980 |
EPX |
| 56-0159291 |
Aug 1981 |
JPX |
Continuation in Parts (2)
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Number |
Date |
Country |
| Parent |
14871 |
Feb 1987 |
|
| Parent |
875450 |
Jun 1986 |
|
Patent Grant
4832701
