Combustion method and apparatus

A method comprising:

• providing a combustion apparatus, the combustion apparatus comprising an outer vessel, an inner conduit, and a jacket, the outer vessel having a first longitudinally extending wall that defines an internal volume of the outer vessel, the inner conduit providing a first fluid passageway that is in communication with the internal volume of the outer vessel, the jacket at least partially surrounding the outer vessel in a manner defining at least a second fluid passageway between the jacket and the first longitudinally extending wall of the outer vessel, the second fluid passageway extending spirally around the first longitudinally extending wall of the outer vessel and decreasing in cross-sectional area as it extends spirally around the first longitudinally extending wall of the outer vessel;
• passing oxygen through the second fluid passageway and into the internal volume of the outer vessel, the decrease in cross-sectional area of the second fluid passageway causing the oxygen that passes through the second fluid passageway to increase in velocity as it passes through the second fluid passageway;
• introducing fuel into the internal volume of the outer vessel;
• combusting the fuel and oxygen at least partially within the internal volume of the outer vessel of the combustion apparatus, the combustion of the fuel and oxygen producing reaction products;
• discharging at least some of the reaction products from the internal volume of the outer vessel of the combustion apparatus via the first fluid passageway of the inner conduit.