The invention provides a double-
necking-down combined spiral-flow type center grading high-temperature-rise
combustion chamber which comprises a diffuser, an inner casing, an outer casing, a
flame tube, a cap cover, a splash blocking disc, a fuel
nozzle and a
flame holder, the inner casing and the outer casing are connected with the
tail end of the diffuser, and the fuel
nozzle is used for conveying
fuel oil to the
flame tube; the flame holder is arranged on the outer side of the
nozzle shell at the downstream end of the fuel nozzle in a sleeving manner and is coaxial with the nozzle shell; the flame holder comprises a first-stage swirler, a second-stage swirler and a third-stage swirler which are sequentially arranged in a sleeved mode, the outlet end face of the downstream of the first-stage swirler is connected with an inner
necking opening, the outlet end face of the downstream of the second-stage swirler is connected with an outer
necking opening, and the outlet end face of the downstream of the third-stage swirler is connected with a variable cross-section circular ring. The flame tube comprises a flame tube inner ring and a flame tube outer ring. By means of multi-path grading and echelon utilization of air, reliable ignition and
combustion stability under the low working condition can be considered, and high-efficiency
smoke-free
combustion under the high working condition can also be considered.