A reactor system includes a fluidized-bed. A fuel and a sulfur absorbent material are eluted through the fluidized-bed. The reactor system may include a heat exchanger having a heat-exchanging portion within a heating zone of the reactor that is hermetically sealed from the heating zone. The reactor may include loose particles of an inert bed material for forming the fluidized-bed. A feed system may be provided to inject a solid fuel composite that includes a mixture of a solid, carbonaceous fuel and a solid reagent into the reactor.

A fluidized bed heat exchanger with a chamber (24) comprises a solid particles inlet port (22), a solid particles outlet port (30), arranged at a distance to the inlet port (22), means (46) for introducing a fluidizing gas from a bottom area into the chamber (24). The heat exchanger further comprises at least two heat transfer means (28) within the one chamber (24), each being provided with a heat transfer medium inlet port (42) and a heat transfer medium outlet port (44), wherein a first heat transfer means (28) is designed as a reheater and second heat transfer means (28) is designed as a superheater to achieve a heat transfer medium temperature and a heat transfer medium pressure above that of the reheater. At least one of the reheater or superheater is made of a multiplicity of heat transfer tubes arranged in a meandering fashion for conveying a heat transfer medium.

A fluidized bed heat exchanger with a chamber (24) comprises a solid particles inlet port (22), a solid particles outlet port (30), arranged at a distance to the inlet port (22), means (46) for introducing a fluidizing gas from a bottom area into the chamber (24). The heat exchanger further comprises at least two heat transfer means (28) within the one chamber (24), each being provided with a heat transfer medium inlet port (42) and a heat transfer medium outlet port (44), wherein a first heat transfer means (28) is designed as a reheater and second heat transfer means (28) is designed as a superheater to achieve a heat transfer medium temperature and a heat transfer medium pressure above that of the reheater. At least one of the reheater or superheater is made of a multiplicity of heat transfer tubes arranged in a meandering fashion for conveying a heat transfer medium.

The invention discloses partial conversion of a hydrocarbon fuel to CO and H.sub.2 within a heat exchanger reformer, prior to injection of the fuel into fuel reactor of a chemical looping combustion system, including reforming portion of the fuel used for the chemical looping combustion system in the heat exchange reformer through reaction with steam and/or other suitable gas, or reforming portion of the fuel used for the chemical looping combustion system in the heat exchange reformer through reaction with recycled flue gas. The invention further discloses the use of recycled flue gas, without the use of a heat exchange reformer prior to injection of the fuel into the fuel reactor of a chemical looping combustion system.

Various aspects provide for a fluidized bed reactor comprising a container having a bed of bed solids and a splashgenerator configured to impart a directed momentum to a portion of the bed solids. A bedwall may separate the bed solids into first and second reaction zones, and the directed momentum may be used to transfer bed solids from one zone to the other. A return passage may provide for return of the transferred bed solids, providing for circulation between the zones. A compact circulating bubbling fluidized bed may be integrated with a reactor having first and second stages, each with its own fluidization gas and ambient. A multistage reactor may comprise a gaswall separating at least the gas phases above two different portions of the bed. A gaslock beneath the gaswall may provide reduced gas transport while allowing bed transport, reducing contamination.

A reactor system and control method. The method includes feeding solid fuel and oxygen containing gas to a first fluidized bed reactor to form a fluidized bed of particles and combusting a first portion of the fuel in the bed with the oxygen containing gas to generate hot bed particles and a first stream of hot flue gas, conveying the first stream to the flue gas channel, transferring hot bed particles including a second portion of the solid fuel at a predetermined hot particles transfer rate from the first reactor to a second fluidized bed reactor, feeding fluidizing gas to the second reactor to form a second fluidized bed, and transferring bed particles from the second reactor to the first. The method includes first and second operation modes. In the first, the fluidizing gas is oxygen containing gas and, in the second, the gas includes steam, CO.sub.2, or inert gas.