Method of Co-Firing Coal or Oil with a Gaseous Fuel in a Furnace

Abstract

Methods for co-firing a fuel containing coal or oil that is injected into a burner in a furnace by injecting a gaseous fuel are disclosed. The gaseous fuel is injected in a manner so as not to consume air that would otherwise combine with the coal or oil in the primary flame. This can be accomplished by injecting the gaseous fuel at a higher or lower velocity than the coal or oil and combustion air are being injected. This can also be accomplished by directing the gaseous fuel being injected away from the primary flame created when the coal or oil burns.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of provisional application Ser. No. 61 / 938,934 filed Feb. 12, 2014.FIELD OF INVENTION[0002]The present invention is directed toward controlling the operation of a furnace and in which coal or oil is burned in combination with a gaseous fuel.BACKGROUND OF THE INVENTION[0003]Coal and oil fired boilers are used to generate steam for many industrial purposes, chief among which is to drive electric generating, steam powered turbines for the electric utility industry. The coal or oil occur in a condensed solid or liquid state and must be ground or pulverized, in the case of coal, or atomized, in the case of oil, before being able to be combusted efficiently in the furnace section of the boiler.[0004]Either of these finely ground or atomized, but still condensed phase, fuels then must be heated to an extent so as to volatilize a portion of the fuel into the gaseous phase before mixing with air and combustion be...

AI Technical Summary

Benefits of technology

[0013]We provide a method by which a more easily burned fuel, such as natural gas, is introduced into a coal or oil burning furnace so that it will not disturb the primary flame structure of the solid or liquid fuel. We disclose methods to inject the gaseous (or more easily burned) fuel into the bulk volume of the furnace without disrupting the operation or safety of the coal or oil fired boiler and then the process by which both the solid or liquid and the gaseous fuel combustion are controlled to safely burn to completion.

[0014]In our method a gaseous fuel is co-fired ether through an existing or new burner or separately by itself, into an existing or new furnace without interfering with the condensed phase flame structure. At the same time, the process allows continued flame stabilization and safety of the condensed phase fuel combustion, furnace and boiler operation, and complete gaseous fuel combustion within the bulk furnace volume away from the primary flame structure.

[0016]Our method involves the safe injection of a gaseous fuel into a furnace volume without interfering with the originally designed operation of a condensed phase, coal or oil burner. This injection may be either through the existing burner, its peripheral openings or through separate furnace wall penetrations. The process is that combustion of the gaseous fuel is purposefully limited in the primary flame structure of the coal or oil burner; thus maintaining original equipment flame safety and stability. But, the subsequent mixing and combustion of gaseous fuel, actually improves the combustion and burn-out of the condensed phase fuel in the bulk volume of the furnace, because of the much higher water of combustion of methane (CH4), with greatly increased free-radical hydrogen activity. This safe injection of the co-fired gaseous fuel must be accomplished, without stealing a significant amount of the necessary combustion air from the primary flame structure of the originally designed condensed phase burner.

Problems solved by technology

The process is that combustion of the gaseous fuel is purposefully limited in the primary flame structure of the coal or oil burner; thus maintaining original equipment flame safety and stability.

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