A heat exchanger (10) suitable for recovering heat from bed material of a fluidized bed boiler (1). The heat exchanger (10) comprises first and second heat exchanger tubes (810, 820) and first and second feeding chambers (310, 320) configured to supply bed material to the first and second heat exchanger tubes (810, 820), respectively. The first heat exchanger tubes (810) are arranged on a first side of a plane (P) that intersects the first feeding chamber (310) and the second heat exchanger tubes (820) are arranged on a second side of the plane (P). The first feeding chamber (310) is configured to supply bed material to the second feeding chamber (320).

An apparatus for controlling flow of a material includes an inlet for receiving the material from a source, and a seal mechanism connected to the inlet, the seal mechanism having a fluidizing bed configured to receive the material from the inlet, a first discharge passageway and a second discharge passageway. The fluidizing bed includes a first transport zone associated with the first discharge passageway and a second transport zone associated with the second discharge passageway, wherein the first and second transport zones are configured to receive transport gas from a transport gas source. The transport gas is controllable to selectively divert a flow of the material into the first discharge passageway and the second discharge passageway.

Disclosed herein are a fluid sand falling type circulating fluidized bed boiler with a plurality of risers for preventing erosion and corrosion of water tubes and increasing combustion efficiency, and a method of operating the same. The fluid sand falling type circulating fluidized bed boiler with a plurality of risers includes a boiler section into which fuel and oxidizer are injected, a riser section connected to the boiler section so that the fuel and fluid sand supplied from the boiler section are introduced from the bottom of the riser section and flow up, and a relay section provided on the boiler section to supply the fluid sand having passed through the riser section to the boiler section, wherein the fuel is injected from the top of the boiler section and burned while flowing down therein.

The invention relates to abed management cycle for a fluidized bed boiler, comprising the steps of: a) providing fresh ilmenite particles as bed material to the fluidized bed boiler; b) carrying out a fluidized bed combustion process; c) removing at least one ash stream comprising ilmenite particles from the fluidized bed boiler; d) separating ilmenite particles from the at least one ash stream; e) recirculating separated ilmenite particles into the bed of the fluidized bed boiler. The invention also relates to a corresponding arrangement for carrying out fluidized bed combustion, comprising a fluidized bed boiler comprising ilmenite particles as bed material; and a system for removing ash from the fluidized bed boiler; wherein the arrangement further comprises a separator for separating ilmenite particles from the re-moved ash; and means for recirculating separated ilmenite particles into the bed of the fluidized bed boiler.

A heat exchanger (10) suitable for recovering heat from bed material of a fluidized bed boiler (1). The heat exchanger (10) comprises first and second heat exchanger tubes (810, 820) and first and second feeding chambers (310, 320) configured to supply bed material to the first and second heat exchanger tubes (810, 820), respectively. The first heat exchanger tubes (810) are arranged on a first side of a plane (P) that intersects the first feeding chamber (310) and the second heat exchanger tubes (820) are arranged on a second side of the plane (P). The first feeding chamber (310) is configured to supply bed material to the second feeding chamber (320).

Systems and methods for coupling a chemical looping arrangement and a supercritical CO.sub.2 cycle are provided. The system includes a fuel reactor, an air reactor, a compressor, first and second heat exchangers, and a turbine. The fuel reactor is configured to heat fuel and oxygen carriers resulting in reformed or combusted fuel and reduced oxygen carriers. The air reactor is configured to re-oxidize the reduced oxygen carriers via an air stream. The air stream, fuel, and oxygen carriers are heated via a series of preheaters prior to their entry into the air and fuel reactors. The compressor is configured to increase the pressure of a CO.sub.2 stream to create a supercritical CO.sub.2 stream. The first and second heat exchangers are configured to heat the supercritical CO.sub.2 stream, and the turbine is configured to expand the heated supercritical CO.sub.2 stream to generate power.

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 circulating fluidized bed boiler is described, comprising a furnace, a loopseal, and a loopseal heat exchanger arranged in the loopseal. The loopseal heat exchanger comprises walls limiting an interior of the loopseal heat exchanger, a first particle outlet for letting out particulate material from the loopseal heat exchanger, an inlet for receiving bed material, heat exchanger tubes arranged in the interior of the loopseal heat exchanger, and a first ash removal channel configured to let out ash from the loopseal heat exchanger. An ash cooler is configured to receive ash from the first ash removal channel. In the loopseal heat exchanger the first ash removal channel is arranged at a lower level than the first particle outlet.

Embodiments of apparatuses and methods for controlling heat for rapid thermal processing of carbonaceous material are provided herein. The apparatus comprises a reactor, a reheater for forming a fluidized bubbling bed comprising an oxygen-containing gas, inorganic heat carrier particles, and char and for burning the char into ash to form heated inorganic particles. An inorganic particle cooler is in fluid communication with the reheater. The inorganic particle cooler comprises a shell portion and a tube portion. The inorganic particle cooler is configured such that the shell portion receives a portion of the heated inorganic particles and the tube portion receives a cooling medium for indirect heat exchange with the portion of the heated inorganic particles to form partially-cooled heated inorganic particles.

Systems and methods for coupling a chemical looping arrangement and a supercritical CO.sub.2 cycle are provided. The system includes a fuel reactor, an air reactor, a compressor, first and second heat exchangers, and a turbine. The fuel reactor is configured to heat fuel and oxygen carriers resulting in reformed or combusted fuel and reduced oxygen carriers. The air reactor is configured to re-oxidize the reduced oxygen carriers via an air stream. The air stream, fuel, and oxygen carriers are heated via a series of preheaters prior to their entry into the air and fuel reactors. The compressor is configured to increase the pressure of a CO.sub.2 stream to create a supercritical CO.sub.2 stream. The first and second heat exchangers are configured to heat the supercritical CO.sub.2 stream, and the turbine is configured to expand the heated supercritical CO.sub.2 stream to generate power.