US 4,488,866 AGranted

Method and apparatus for burning high nitrogen-high sulfur fuels

AssigneePhillips Petroleum Company

InventorsRobert M. Schirmer, Henry E. Alquist

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Abstract

A method of minimizing the production of SO.sub.x and NO.sub.x in the burning of a fuel containing significant amounts of SO.sub.x and NO.sub.x precursors in which the fuel is treated to remove significant amounts of SO.sub.x precursors without the removal of significant amounts of NO.sub.x precursors and the fuel is thereafter burned in a two-stage, rich-lean burning step in which significant amounts of the NO.sub.x precursors are converted to N.sub.2. Treating the fuel to remove SO.sub.x precursors is preferrably carried out in the presence of an oxidizing agent, such as H.sub.2 O.sub.2, 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.sub.x precursors.

Claims33

Dependent claims

A method for minimizing the production of SO.sub.x and NO.sub.x in the burning of a primary fuel containing significant amounts of SO.sub.x and NO.sub.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.sub.x precursors from said primary fuel but insufficient to remove significant amounts of said NO.sub.x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO.sub.x precursors and reduced amounts of SO.sub.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.sub.x precursors to N.sub.2, to produce an effluent containing significant amounts of N.sub.2 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 N.sub.2 and CO.sub.2 and containing substantially reduced amounts of SO.sub.x and NO.sub.x.

3 more elements

A method for minimizing the production of SO.sub.x and NO.sub.x in the burning of a primary fuel containing significant amounts of SO.sub.x and NO.sub.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.sub.x precursors from said primary fuel but insufficient to remove significant amounts of said NO.sub.x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO.sub.x precursors and reduced amounts of SO.sub.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.sub.x precursors to N.sub.2, to produce an effluent containing significant amounts of N.sub.2 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 N.sub.2 and CO.sub.2 and containing substantially reduced amounts of SO.sub.x and NO.sub.x.

3 more elements

A method for minimizing the production of SO.sub.x and NO.sub.x in the burning of a primary fuel containing significant amounts of SO.sub.x and NO.sub.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.sub.x precursors from said primary fuel but insufficient to remove significant amounts of said NO.sub.x precursors from said primary fuel, to produce a primary fuel containing significant amounts of NO.sub.x precursors and reduced amounts of SO.sub.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.sub.x precursors to N.sub.2, to produce an effluent containing significant amounts of N.sub.2 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 N.sub.2 and CO.sub.2 and containing substantially reduced amounts of SO.sub.x and NO.sub.x.

3 more elements

Dependencies are inferred from the claim text.