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US 6,729,248 B2Granted
Low sulfur coal additive for improved furnace operation
AssigneeADA Environmental Solutions, LLC
InventorsStephen Allen Johnson, John Wurster, John Philip Comer
Life of this patent
Estimating the term…
Abstract
The present invention is directed to additives for coal-fired furnaces, particularly furnaces using a layer of slag to capture coal particles for combustion. The additive(s) include iron, mineralizer(s), handling aid(s), flow aid(s), and/or abrasive material(s). The iron and mineralizers can lower the melting temperature of ash in low-iron, high alkali coals, leading to improved furnace performance.
Claims34
A method for combusting coal, comprising:
- providing a coal-containing feed material to a coal combustion chamber;
- contacting the feed material with an iron-containing additive, wherein the iron-containing additive is in the form of a free-flowing particulate having a P90 size of less than or equal to about 300 microns;
- and
- melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted, wherein the coal-containing feed material comprises ash and less than about 1 wt. % (dry basis of the coal-containing feed material) sulfur, with the ash containing less than about 10 wt. % (dry basis of the ash) iron, and at least about 20 wt. % (dry basis of the ash) alkali.
1 more element
A method for combusting coal, comprising:
- inputting a coal-containing feed material to a coal combustion chamber;
- contacting the feed material with an iron-containing additive, wherein the iron-containing additive comprises at least about 50 wt. % (dry basis of the additive) iron and at least about 1 wt. % (dry basis of the additive) mineralizer;
- and
- melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted.
1 more element
A method for combusting coal, comprising:
- introducing a coal-containing feed material to a coal combustion chamber;
- contacting the feed material with an iron-containing additive, wherein the iron-containing additive comprises at least about 50 wt. % (dry basis of the additive) iron and the iron is in the form of a mixture of ferrous and ferric oxides;
- and
- melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted, wherein the mineralizer is a zinc compound, wherein the coal-containing feed material includes coal particles entrained in an oxygen-containing gas, wherein the coal particles have a P90 size of less than or equal to about 0.25 inch, and wherein the coal-containing feed material comprises ash and less than about 1.5 wt. % (dry basis of the coal-containing feed material) sulfur, with the ash containing less than about 10 wt. % (dry basis of the ash) iron, and at least about 15 wt. % (dry basis of the ash) calcium.
1 more element
The method of claim wherein the coal combustion chamber is part of a cyclone furnace and at least some of the iron is in the form of wustite.
A method for combusting coal, comprising:
- providing a coal-containing feed material to a coal combustion chamber;
- contacting the feed material with an iron-containing additive, wherein the iron-containing additive is in the form of a free-flowing particulate having a P90 size of less than or equal to about 300 microns;
- and
- melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted, wherein the iron-containing additive comprises at least about 50 wt. % (dry basis of the additive) iron and at least about 1 wt. % (dry basis of the additive) mineralizer.
1 more element
A method for combusting coal, comprising:
- providing a coal-containing feed material to a coal combustion chamber;
- contacting the feed material with an iron-containing additive, wherein the iron-containing additive is in the form of a free-flowing particulate having a P90 size of less than or equal to about 300 microns;
- and
- melting at least a portion of the coal-containing feed material and iron-containing additive to form a slag layer on at least a portion of a surface of the combustion chamber, whereby coal in the coal-containing feed material is captured by the slag layer and combusted, wherein an injection rate of the iron-containing additive into the combustion chamber ranges from about 10 to about 50 lb/ton coal.
1 more element
Dependencies are inferred from the claim text.