Patent ID: 7080517

Claim:
A method comprising: providing a combustion apparatus comprising an outer vessel and an inner conduit, the outer vessel having a first longitudinally extending wall extending generally along a central axis, the outer vessel further having a forward end and a rearward end, the rearward end being longitudinally spaced from the forward end, the inner conduit being at least partially within the outer vessel and having a forward intake port, a rearward discharge port, and a second longitudinally extending wall extending generally along the central axis between the intake and discharge ports and generally coaxial with the first longitudinally extending wall, the second longitudinally extending wall having at least a forward longitudinal portion which is spaced radially inwardly of the first longitudinally extending wall, the intake and discharge ports and the second longitudinally extending wall defining a central fluid passage through the inner conduit, the intake port being between the forward and rearward ends of the outer vessel and being spaced from both of the forward and rearward ends of the outer vessel, the outer vessel further comprising a forward combustion region and a rearward fluid passage, the forward combustion region being at least partially circumscribed by the first longitudinally extending wall and being longitudinally forward of the intake port of the inner conduit, the rearward fluid passage being longitudinally rearward of the intake port of the inner conduit, the rearward fluid passage being defined between the first and second longitudinally extending walls and being generally annular in shape; introducing feed air into the rearward fluid passage in a generally tangential direction relative to the rearward fluid passage in a manner such that at least some of the feed air swirls around the second longitudinally extending wall; introducing a fuel into the combustion region; facilitating mixing of the fuel and the feed air in the combustion region; causing a combustion reaction of the mixed fuel and feed air in the combustion region in a manner such that at least 70% of the fuel entering the combustion region is combusted in either the combustion region or the rearward fluid passage to form combustion reaction products; discharging the combustion reaction products longitudinally rearward through the central fluid passage of the inner conduit.