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.

Abstract: An apparatus and method for combusting carbonaceous fuels includes a reaction chamber defining a reaction zone and means for injecting fuel and oxidizer gas in a manner to produce in the reaction zone a wheel-type flow of the fuel-gas mixture. In preferred embodiments, the high velocity wheel-type flow operates to suspend fuel or other reactant particles in the swirling gas for residence times required for substantially complete reaction of the particles prior to the particles impinging against the walls of the reaction chamber. High angular veocities and the resulting centrifugal forces operate to remove substantially all slag from the gas as it approaches the downstream end of the reaction chamber. Operating temperatures are maintained at a level to avoid excessive volatilization of slag and thereby promote separation of liquid slag from the gaseous reaction products.