Methods and apparatus for carbon dioxide-oxygen-coal combustion

Abstract

A burner and method for oxidizing solid fuels wherein the burner has a lance having one or more nozzle feeds and one or more nozzle outlets concentrically surrounded by a primary oxidant passage which is concentrically surrounded by a secondary oxidant passage wherein the primary and secondary oxidant passages communicate at their proximal ends with a gas supply, the lance having a distal and proximal end and the one or more nozzle feeds is in communication with a gas supply.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims priority from U.S. provisional patent application Ser. No. 61 / 369,894 filed on Aug. 2, 2010.BACKGROUND OF THE INVENTION[0002]The invention provides for the use of a burner for carbon dioxide-oxygen-coal combustion processes. More particularly, the invention provides for a lance in connection with a burner to more effectively combust a solid fuel, such as coal, with an oxidant mixture comprising predominantly of carbon dioxide and oxygen, such as may be formed by the addition of substantially pure oxygen with flue gas recirculated from said combustion process.[0003]Air-coal burners and steam boilers for electrical power generation have been developed over many years through a process of trial and error. Typically, the motive air that is used to pulverize the coal is also used as the primary air in the air-coal burners. Primary air and pulverized coal typically flow through an annular conduit that is mesial to coaxial...

AI Technical Summary

Benefits of technology

[0007]The invention provides for the use of a predominantly carbon dioxide-oxygen oxidant in place of air oxidant in a solid fuel burner. The solid fuel herein after referred to as coal may be any solid hydrocarbon fuel, such as various grades of coal, peat, coke, or biomass The invention further provides for an improved coal burner assembly which comprises an air-coal burner equipped with an oxidant lance, thereby providing a better combustion with an oxygen-carbon dioxide-coal mixture than an air-coal mixture.

Problems solved by technology

However, substitution of the nitrogen diluent in the air oxidant with carbon dioxide decreases the coal combustion flame velocity more rapidly than the coal flammability limit and flame temperature.

If one tries to increase the carbon dioxide-oxygen-coal flame velocity to acceptable values by increasing the primary oxidant oxygen in carbon dioxide concentration, then the fire hazard in the coal grinding mill also increases.

Typical biomass feed examples include wood chips, wood charcoal, pelletized grass, and similar materials Biomass, particularly wet biomasses can further lead to reductions in flame speed and more unstable combustion conditions.

As such the addition of biomass can lead combustion related problems that may not be overcome by increasing the oxygen content of the secondary air.

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