Method for reducing coke deposition

Patent metadata

Field	Value
Publication number	US-9187700-B2
Application number	US-201213350108-A
Country	US
Kind code	B2
Filing date	Jan 13, 2012
Priority date	Jan 13, 2012
Publication date	Nov 17, 2015
Grant date	Nov 17, 2015

Abstract

A method for reducing coke deposits includes heating an alcohol-fuel mixture to decompose alcohol and form water to produce a fuel-water mixture and delivering the fuel-water mixture to a carbon-steam gasification catalyst. The fuel-water mixture reacts with the carbon-steam gasification catalyst such that coke deposits are prevented from remaining in a space near the carbon-steam gasification catalyst.

First claim

The invention claimed is:

1. A method for reducing coke deposits, the method comprising:
combining an alcohol with a fuel to produce an alcohol-fuel mixture;
heating the alcohol-fuel mixture to decompose alcohol and form water to produce a fuel-water mixture, wherein heating the alcohol-fuel mixture occurs prior to introduction of a carbon-steam gasification catalyst; and
delivering the fuel-water mixture to the carbon-steam gasification catalyst, wherein the fuel-water mixture reacts with the carbon-steam gasification catalyst such that coke deposits are prevented from remaining in a space near the carbon-steam gasification catalyst.

2. The method of claim 1 , wherein the carbon-steam gasification catalyst coats a wall surface such that coke deposits are prevented from remaining on the wall surface.

3. The method of claim 2 , wherein the wall surface belongs to a component selected from the group consisting of a heat exchanger, a transfer line and a nozzle.

4. The method of claim 1 , wherein the carbon-steam gasification catalyst and a cracking catalyst form a bifunctional catalyst such that coke deposits are prevented from remaining on the bifunctional catalyst.

5. The method of claim 1 , wherein the alcohol-fuel mixture is formed by adding an alcohol to a hydrocarbon fuel.

6. The method of claim 1 , wherein the carbon-steam gasification catalyst is selected from the group consisting of Na2CO3, K2CO3, Cs2CO3, MgCO3, CaCO3, SrCO3, BaCO3 and combinations thereof.

7. The method of claim 1 , wherein the alcohol-fuel mixture is heated to a temperature of greater than about 426° C. (800° F.) to decompose the alcohol.

8. The method of claim 7 , wherein the alcohol is selected from the group consisting of ethanol, 2-propanol, t-butanol and combinations thereof.

9. The method of claim 1 , further comprising:
adding an alcohol decomposition catalyst to the alcohol-fuel mixture before heating the alcohol-fuel mixture to decompose the alcohol.

10. The method of claim 9 , wherein the alcohol decomposition catalyst is selected from the group consisting of zeolites, silica-alumina, heteropolyacid catalysts, transitional metal oxides on an alumina support and combinations thereof.

11. The method of claim 9 , wherein the alcohol-fuel mixture comprises between about 0.01% and about 0.1% alcohol decomposition catalyst by weight.

12. The method of claim 9 , wherein the alcohol-fuel mixture is heated to a temperature of greater than about 370° C. (700° F.) to decompose the alcohol.

13. The method of claim 9 , wherein the alcohol is selected from the group consisting of ethanol, propanols, butanols and combinations thereof.

14. The method of claim 1 , wherein the alcohol-fuel mixture, before heating the alcohol-fuel mixture to decompose the alcohol, comprises between about 0.3% and about 8.2% alcohol by weight, and wherein the fuel-water mixture comprises between about 0.1% and about 2% water by weight.

15. A method for preventing coke deposits on and removing coke deposits from a fuel passage, the method comprising:
substantially coating a surface of the fuel passage with a carbon-steam gasification catalyst;
combining an alcohol with a fuel to produce an alcohol-fuel mixture;
heating the alcohol-fuel mixture to decompose alcohol and form water to produce a fuel-water mixture, wherein heating the alcohol-fuel mixture occurs prior to introduction of the carbon-steam gasification catalyst; and
delivering the fuel-water mixture past the fuel passage surface, wherein the fuel-water mixture reacts with the carbon-steam gasification catalyst to prevent formation of coke deposits and remove formed coke deposits on the fuel passage surface.

16. The method of claim 15 , wherein the alcohol-fuel mixture is heated to a temperature of greater than about 426° C. (800° F.) to decompose the alcohol.

17. The method of claim 15 , further comprising:
adding an alcohol decomposition catalyst to the alcohol-fuel mixture before heating the alcohol-fuel mixture to decompose the alcohol, wherein the alcohol-fuel mixture is heated to a temperature of greater than about 370° C. (700° F.) to decompose the alcohol.

18. The method of claim 17 , wherein the alcohol decomposition catalyst is selected from the group consisting of zeolites, silica-alumina, heteropolyacid catalysts, transitional metal oxides on an alumina support and combinations thereof.

19. A method for preventing coke deposition and removing coke from a catalytic cracking system, the method comprising:
preparing a bifunctional catalyst within the fluid catalytic cracking system, the bifunctional catalyst comprising:
a cracking catalyst for cracking hydrocarbons; and
a carbon-steam gasification catalyst;
combining an alcohol with a hydrocarbon feedstock that is to be cracked to form an alcohol-hydrocarbon mixture;
heating the alcohol-hydrocarbon mixture to decompose the alcohol to form water and produce a hydrocarbon-water mixture, wherein heating the alcohol-hydrocarbon mixture occurs prior to introduction of the bifunctional catalyst; and
delivering the hydrocarbon-water mixture to the bifunctional catalyst, wherein the cracking catalyst reacts with the hydrocarbons in the hydrocarbon-water mixture to break carbon-carbon hydrocarbon bonds and the water in the hydrocarbon-water mixture reacts with the carbon-steam gasification catalyst to prevent formation of coke deposits and remove formed coke deposits from the bifunctional catalyst.

20. The method of claim 19 , wherein the cracking catalyst is selected from the group consisting of zeolites, alumina, silica and combinations thereof, and wherein the carbon-steam gasification catalyst is selected from the group consisting of Na2CO3, K2CO3, Cs2CO3, MgCO3, CaCO3, SrCO3, BaCO3 and combinations thereof.

Assignees

• Huang He
• Haas Martin
• United Technologies Corp

Inventors

• Huang He
• Haas Martin

Classifications

• C10G9/36 Primary

  with heated gases or vapours · CPC title