Claims
- 1. A method for the entrained-flow combustion of a carbon-, nitrogen- and sulfur-containing fuel for substantially reducing emission of gaseous sulfur compounds and nitrogenous compounds formed during the combustion of the fuel with a substoichiometric amount of oxygen-comprising;
- introducing said fuel, an inorganic alkaline absorbent and an oxygen-containing gas into a first combustion sulfur capture zone of an entrained-flow combustor to form a fluent mixture therein of fuel and absorbent entrained in said gas,
- the oxygen being present in said zone in an amount to provide from about 25%-40% of the total stoichiometric amount required for the complete combustion of the fuel,
- the inorganic alkaline absorbent being present in an amount to provide a molar ratio of alkaline absorbent to sulfur compounds of from about 1.0:1 to 3.0:1, said ratio including any alkaline absorbents contained in the fuel;
- reacting said fuel and absorbent entrained in said oxygen-containing gas by maintaining them in said zone at a temperature from about 1000.degree.-1800.degree. K. for a time sufficient
- (a) to gasify at least about 75% of the carbon content of the fuel and substantially all of the sulfur in a fuel,
- (b) to combust the gasified fuel and oxygen to produce a fuel-rich stoichiometry in the gas-phase, and
- (c) to react in excess of about 70% of the fuel sulfur with the inorganic alkaline absorbent to form a solid alkaline sulfide compound
- introducing the resultant combustion mixture into a second combustion zone;
- maintaining said mixture at a temperature in the range of 1800.degree. K.-2500.degree. K. in said second combustion zone while introducing additional air in an amount to provide about 45%-75% of the total stoichiometric amount of air required for complete combustion of the fuel;
- maintaining said mixture including said alkaline sulfide compound, at said temperature for a time sufficient to reduce said nitrogenous compound content to a desired level; and
- discharging said mixture having a substantially reduced gaseous sulfur compound and nitrogenous compound content.
- 2. The method of claim 1 wherein said solid sulfur compounds are removed from the gas stream between said first and second combustion zones.
- 3. The method of claim 1 wherein said alkaline absorbent is selected from the group consisting of the oxides, hydroxides, and carbonates of magnesium, calcium, and sodium.
- 4. The method of claim 1 wherein said temperature is maintained in said first and second combustion zones by the introduction thereto of preheated air.
- 5. The method of claim 1 further including introducing the combustion products from said second combustion zone into at least a third combustion zone and maintaining said products at a temperature of from about 1600.degree. to 2000.degree. K. while completing the combustion by the introduction of additional air in an amount to provide from about 100% to about 120% of the total stoichiometric requirements for complete combustion of the fuel.
Parent Case Info
This is a division of application Ser. No. 344,067 filed Feb. 2, 1982, which is a continuation-in-part of application Ser. No. 239,943, filed Mar. 3, 1981, and since abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4381718 |
Carver et al. |
May 1983 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
344067 |
Feb 1982 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
239943 |
Mar 1981 |
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