Method and apparatus for burning high nitrogen-high sulfur fuels

• US 4,488,866 A
• Filed: 08/03/1982
• Issued: 12/18/1984
• Est. Priority Date: 08/03/1982
• Status: Expired due to Fees

• Current Assignee: Phillips Petroleum Company (ConocoPhillips)
• Original Assignee: Phillips Petroleum Company (ConocoPhillips)
• Inventors: Schirmer, Robert M., Alquist, Henry E.
• Primary Examiner(s): Dority, Jr., Carroll B.
• Application Number:
  US06/404,682
• Time in Patent Office: 868 Days
• Field of Search: 431/2, 431/4, 208/208 R, 110/342
• US Class Current: 431/4
• CPC Class Codes: C10L 10/02 for reducing smoke development
• CPC Class Codes: C10L 9/02 by chemical means
• CPC Class Codes: F23C 6/04 in series connection consuming smoke or fumes in separate combustion apparatus F23G7/06
• CPC Class Codes: F23J 7/00 Arrangement of devices for supplying chemicals to fire
• CPC Class Codes: F23L 2900/07004 Injecting liquid or solid materials releasing oxygen, e.g. perchlorate, nitrate, peroxide, and chlorate compounds, or appropriate mixtures thereof
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

A method of minimizing the production of SO_x and NO_x in the burning of a fuel containing significant amounts of SO_x and NO_x precursors in which the fuel is treated to remove significant amounts of SO_x precursors without the removal of significant amounts of NO_x precursors and the fuel is thereafter burned in a two-stage, rich-lean burning step in which significant amounts of the NO_x precursors are converted to N₂. Treating the fuel to remove SO_x precursors is preferrably carried out in the presence of an oxidizing agent, such as H₂ O₂, a reducing agent, such as hydrogen, and/or steam, and still more preferably, the oxidizing agent, the reducing agent and steam are generated by burning an auxiliary fuel and passing the effluent thereof to the step of treating the fuel to remove SO_x precursors.

Claims

1. A method for minimizing the production of SO_x and NO_x in the burning of a primary fuel containing significant amounts of SO_x and NO_x precursors, comprising:

(a) burning an auxiliary fuel in the presence of a combustion supporting material, sufficient to supply oxygen in an amount greater than the stoichiometric amount necessary to burn all of said auxiliary fuel, and for a residence time sufficient to produce significant amounts of hydrogen and abruptly terminating said step of burning said auxiliary fuel, before significant amounts of other products are formed from the thus produced hydrogen, to produce an auxiliary fuel effluent containing significant amounts of hydrogen;

(b) contacting said primary fuel with said auxiliary effluent in a hydrodesulfurization step, under conditions sufficient to remove significant amounts of SO_x precursors from said primary fuel but insufficient to remove significant amounts of said NO_x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO_x precursors and reduced amounts of SO_x precursors;

(c) carrying out fuel-rich combustion by burning the thus hydrodesulfurized primary fuel in a combustion zone in the presence of a combustion supporting material, sufficient to supply oxygen in an amount less than the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to convert a major portion of said NO_x precursors to N₂, to produce an effluent containing significant amounts of N₂ and unburned and partially burned fuel;

(d) abruptly terminating said fuel-rich combustion and initiating fuel-lean combustion; and

(e) carrying out fuel-lean combustion of said effluent containing significant amounts of unburned and partially burned fuel by burning said effluent in the presence of an additional amount of combustion supporting material, sufficient to supply oxygen in an amount sufficient to provide an overall amount of oxygen at least as great as the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to essentially complete the combustion of said primary fuel, to produce a flue gas predominating in N₂ and CO₂ and containing substantially reduced amounts of SO_x and NO_x.

11. A method in accordance with claim 1 wherein the step of contacting the primary fuel to remove SO_x precursors is carried out in the presence of an alkaline material.

12. A method in accordance with claim 11 wherein the alkaline material is an alkaline carbonate.

13. A method in accordance with claim 12 wherein the alkaline carbonate is sodium carbonate.

14. A method in accordance with claim 11 wherein the alkaline material is adapted to form carbonates by a reaction with CO₂.

15. A method in accordance with claim 1 wherein a normally gaseous off-gas is separated from the effluent of the step of contacting the primary fuel to remove SO_x precursors and at least a part of said off-gas is recycled to said step of contacting the primary fuel to remove SO_x precursors.

16. A method in accordance with claim 1 wherein a normally gaseous off-gas is separated from the effluent of the step of contacting the primary fuel to remove SO_x precursors, the step of burning the auxiliary fuel is a two-stage, rich-lean burning step and at least a part of said off-gas is burned in said two-stage, rich-lean burning step.

17. A method in accordance with claim 16 wherein at least a part of the off gas is burned in the fuel-lean stage of the two-stage, rich-lean burning step.

18. A method in accordance with claim 1 wherein a normally gaseous off gas is separated from the effluent of the step of contacting the primary fuel to remove SO_x precursors, said off gas is treated to remove a hydrogen-rich portion and said hydrogen-rich portion is recycled to said step of contacting the primary fuel to remove SO_x precursors.

19. A method in accordance with claim 1 wherein the step of contacting the primary fuel to remove SO_x precursors is carried out in the presence of water supplied by at least one of the steps of adding water to the step of burning the auxiliary fuel, utilizing water to terminate the step of burning the auxiliary fuel, adding water to the effluent from the step of burning the auxiliary fuel and adding water to the step of contacting the primary fuel to remove SO_x precursors from the fuel.

2. A method for minimizing the production of SO_x and NO_x in the burning of a primary fuel containing significant amounts of SO_x and NO_x precursors, comprising:

(a) burning an auxiliary fuel in the presence of a combustion supporting material to produce an auxiliary fuel effluent;

(b) contacting said primary fuel with said auxiliary fuel effluent in the presence of an oxidizing agent, produced by at least one of the steps of producing an oxidizing agent during the step of burning the auxiliary fuel, adding an oxidizing agent during the step of burning the auxiliary fuel, utilizing an oxidizing agent to terminate the step of burning the auxiliary fuel, adding an oxidizing agent to the effluent from the step of burning the auxiliary fuel and adding an oxidizing agent to said step of contacting said primary fuel with said auxiliary fuel effluent, under conditions sufficient to remove significant amounts of SO_x precursors from said primary fuel but insufficient to remove significant amounts of said NO_x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO_x precursors and reduced amounts of SO_x precursors;

(c) carrying out fuel-rich combustion by burning the thus contacted primary fuel in a combustion zone in the presence of a combustion supporting material, sufficient to supply oxygen in an amount less than the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to convert a major portion of said NO_x precursors to N₂, to produce an effluent containing significant amounts of N₂ and unburned and partially burned fuel;

(d) abruptly terminating said fuel-rich combustion and initiating fuel-lean combustion; and

(e) carrying out fuel-lean combustion of said effluent containing significant amounts of unburned and partially burned fuel by burning said effluent in the presence of an additional amount of combustion supporting material, sufficient to supply oxygen in an amount sufficient to provide an overall amount of oxygen at least as great as the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to essentially complete the combustion of said primary fuel, to produce a flue gas predominating in N₂ and CO₂ and containing substantially reduced amounts of SO_x and NO_x.

3. A method in accordance with claim 2 wherein the step of contacting primary fuel to remove SO_x precursors is carried out in the presence of water supplied by at least one of the steps of adding water to the step of burning the auxiliary fuel, utilizing water to terminate the step of burning the auxiliary fuel, adding water to the effluent from the step of burning the auxiliary fuel and adding water to the step of contacting the primary fuel to remove SO_x precursors.

4. A method in accordance with claim 3 wherein the step of contacting the primary fuel to remove SO_x precursors is carried out in the presence of an alkaline material.

5. A method in accordance with claim 4 wherein the alkaline material is an alkaline carbonate.

6. A method in accordance with claim 5 wherein the alkaline carbonate is sodium carbonate.

7. A method in accordance with claim 4 wherein the alkaline material is a material adapted to form carbonates by a reaction with CO₂.

8. A method in accordance with claim 2 wherein the oxidizing agent is hydrogen peroxide.

9. A method in accordance with claim 8 wherein the hydrogen peroxide is produced during the step of burning the auxiliary fuel by burning said auxiliary fuel in the presence of a combustion-supporting material, sufficient to supply oxygen in an amount significantly greater than the stoichiometric amount necessary to burn all of said auxiliary fuel, and produce an effluent containing significant amounts of hydrogen peroxide, abruptly terminating the step of burning the auxiliary fuel, before significant amounts of hydrogen peroxide form other products.

10. A method in accordance with claim 9 wherein the step of contacting the primary fuel to remove SO_x precursors is carried out in the presence of water supplied by at least one of the steps of adding water to the step of burning the auxiliary fuel, utilizing water to terminate the step of burning the auxiliary fuel, adding water to the effluent of the step of burning the auxiliary fuel and adding water to the step of contacting the primary fuel to remove SO_x precursors.

22. A method in accordance with claim 2 wherein the alkaline material is an alkaline carbonate.

23. A method in accordance with claim 22 wherein the alkaline material is sodium carbonate.

20. A method for minimizing the production of SO_x and NO_x in the burning of a primary fuel containing significant amounts of SO_x and NO_x precursors, comprising:

(a) burning an auxiliary fuel in the presence of a combustion supporting material to produce an auxiliary fuel effluent;

(b) contacting said primary fuel with said auxiliary fuel effluent in the presence of water, produced by at least one of the steps of adding water during the step of burning the auxiliary fuel, utilizing water to terminate the step of burning the auxiliary fuel, adding water to the effluent from the step of burning the auxiliary fuel and adding water to said step of contacting said primary fuel with said auxiliary fuel effluent, under conditions sufficient to remove significant amounts of SO_x precursors from said primary fuel but insufficient to remove significant amounts of said NO_x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO_x precursors and reduced amounts of SO_x precursors;

(c) carrying out fuel-rich combustion by burning the thus contacted primary fuel in a combustion zone in the presence of a combustion supporting material, sufficient to supply oxygen in an amount less than the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to convert a major portion of said NO_x precursors to N₂, to produce an effluent containing significant amounts of N₂ and unburned and partially burned fuel;

(d) abruptly terminating said fuel-rich combustion and initiating fuel-lean combustion; and

(e) carrying out fuel-lean combustion of said effluent containing significant amounts of unburned and partially burned fuel by burning said effluent in the presence of an additional amount of combustion supporting material, sufficient to supply oxygen in an amount sufficient to provide an overall amount of oxygen at least as great as the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to essentially complete the combustion of said primary fuel, to produce a flue gas predominating in N₂ and CO₂ and containing substantially reduced amounts of SO_x and NO_x.

21. A method in accordance with claim 20 wherein the step of contacting the primary fuel to remove SO_x precursors is carried out in the presence of an alkaline material.

24. A method in accordance with claim 21 wherein the alkaline material is an alkaline material adapted to form carbonates by reaction with CO₂.

25. A method in accordance with claim 21 wherein the alkaline material comprises sodium hydroxide and calcium hydroxide.

26. A method for minimizing the production of SO_x and NO_x in the burning of a primary fuel containing significant amounts of SO_x and NO_x precursors, comprising:

(a) burning an auxiliary fuel in the presence of a combustion supporting material to produce an auxiliary fuel effluent;

(b) contacting said primary fuel with said auxiliary fuel effluent in the presence of an alkaline material;

(c) carrying out fuel-rich combustion by burning the thus contacted primary fuel in a combustion zone in the presence of a combustion supporting material, sufficient to supply oxygen in an amount less than the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to convert a major portion of said NO_x precursors to N₂, to produce an effluent containing significant amounts of N₂ and unburned and partially burned fuel;

(d) abruptly terminating said fuel-rich combustion and initiating fuel-lean combustion; and

(e) carrying out fuel-lean combustion of said effluent containing significant amounts of unburned and partially burned fuel by burning said effluent in the presence of an additional amount of combustion supporting material, sufficient to supply oxygen in an amount sufficient to provide an overall amount of oxygen at least as great as the stoichiometric amount necessary to burn all of said primary fuel, and for a residence time sufficient to essentially complete the combustion of said primary fuel, to produce a flue gas predominating in N₂ and CO₂ and containing substantially reduced amounts of SO_x and NO_x.

27. A method in accordance with claim 26 wherein the alkaline material is an alkaline carbonate.

28. A method in accordance with claim 27 wherein the alkaline carbonate is sodium carbonate.

29. A method in accordance with claim 26 wherein the alkaline material is adapted to form carbonates by reaction with CO₂.

30. A method in accordance with claim 26 wherein the alkaline material comprises sodium hydroxide and calcium hydroxide.

31. A method in accordance with claim 26 wherein a normally gaseous off-gas is separated from the effluent of the step of contacting the primary fuel to remove SO_x precursors and at least a part of said off-gas is burned in the step of burning the auxiliary fuel.

32. A method in accordance with claim 26 wherein a normally gaseous off-gas is separated from the effluent of the step of contacting the primary fuel to remove SO_x precursors, the step of burning the auxiliary fuel is a two-stage, rich-lean burning step and at least a part of said off-gas is burned in said two-stage, rich-lean burning step.

33. A method in accordance with claim 32 wherein at least a part of the off gas is burned in the fuel-lean stage of the two-stage, rich-lean burning step.