Method and apparatus for in-flight combustion of carbonaceous fuels

Abstract

A method and apparatus for combusting solid fuel by introducing a mixture of fuel particles and carrier fluid into a reaction chamber near the center of one end of a combustion chamber and injecting oxidizer gas tangentially into the chamber to establish a swirling flow of gas, fuel particles, and combustion products within a region adjacent the chamber walls. The mass flow rates of oxidizer gas and fuel are regulated to maintain a relatively oxygen-rich stoichiometry within an annular region and a relatively fuel-rich stoichiometry within a central region, and to cause flow of the oxidizer gas and combustion products thru the reaction chamber with throughput residence times of the order of a few hundred milliseconds. This combination of a fuel-rich core portion and a relatively oxygen-rich annular zone effects oxidation of most of the carbon content of the fuel before it reaches the walls and avoids reduction of metal compounds in the fuel, all without overall excess-air combustion. Combustion temperatures are sufficient to fuse most non-combustibles in the fuel into molten slag but without significant volatilization of the slag, whereby most of the non-combustibles are centrifugally deposited as molten slag on the chamber wall and thereby separated from the combustion products before the latter exit from the chamber.