A dual-bed system for preventing a boiler heating surface from being contaminated comprises a fluidized bed, a cyclone separator, a coal ash distributor, an ash-coal mixer, a lower pyrolysis bed, a return feeder and a cleaner, wherein the cyclone separator is connected with the upper lateral side of the fluidized bed; the inlet end of the coal ash distributor; the two outlets of the coal ash distributor are respectively connected with the inlet of the return feeder and the inlet of the ash-coal mixer; the outlet of the ash-coal mixer is connected with the inlet of the lower pyrolysis bed; the return feeder close to the lower lateral side of the fluidized bed is connected with the inlet on the lower lateral side of the fluidized bed; and the outlet of the cleaner is connected with the inlet on the lower lateral side of the fluidized bed.

The object of the invention is a combustion method for a solid feed using a chemical loop wherein an oxygen-carrying material circulates, said method comprising at least: contacting the solid feed particles in the presence of metallic oxide particles in a first reaction zone (R1) operating in dense fluidized bed mode, carrying out combustion of the gaseous effluents from first reaction zone (R1) in the presence of metallic oxide particles in a second reaction zone (R2), separating in a separation zone (S3) the unburnt particles and the metallic oxide particles within a mixture coming from second reaction zone (R2), re-oxidizing the metallic oxide particles in an oxidation zone (R4) prior to sending them back to first zone (R1).

A system for converting fuel may include a first moving bed reactor, a second reactor, and a non-mechanical valve. The first moving bed reactor may include at least one tapered section and multiple injection gas ports. The multiple injection gas ports may be configured to deliver a fuel to the first moving bed reactor. The first moving bed reactor may be configured to reduce an oxygen carrying material with a fuel by defining a countercurrent flowpath for the fuel relative to the oxygen carrying material. The second reactor may communicate with the first moving bed reactor and may be operable to receive an oxygen source. The second reactor may be configured to regenerate the reduced oxygen carrying material by oxidation.

Methods and devices for combusting a carbonaceous fuel in an oxy-combustion fluidized bed reactor involving controlling the local oxygen content within the oxy-combustion reactor to specified levels. The carbonaceous fuel and an oxygen-containing gas are introduced into a fluidized bed reactor and eluted through a fluidized bed of an inert material, dolomite or a combination thereof to combust the fuel and oxygen to produce at least CO.sub.2 and steam. The oxygen-containing gas is a mixture of oxygen, recycled CO.sub.2 and steam and has sufficient oxygen added to the recycled CO.sub.2 and steam that the mixture contains 7-20 mole % oxygen. The carbonaceous fuel and the oxygen-containing gas are introduced into the fluidized bed at a location in sufficiently close proximity to each other to avoid producing a reducing atmosphere at the location. At least a portion of the produced CO.sub.2 and steam are recycled to the reactor.

Methods and devices for combusting a carbonaceous fuel in an oxy-combustion fluidized bed reactor involving controlling the local oxygen content within the oxy-combustion reactor to specified levels. The carbonaceous fuel and an oxygen-containing gas are introduced into a fluidized bed reactor and eluted through a fluidized bed of an inert material, dolomite or a combination thereof to combust the fuel and oxygen to produce at least CO.sub.2 and steam. The oxygen-containing gas is a mixture of oxygen, recycled CO.sub.2 and steam and has sufficient oxygen added to the recycled CO.sub.2 and steam that the mixture contains 7-20 mole % oxygen. The carbonaceous fuel and the oxygen-containing gas are introduced into the fluidized bed at a location in sufficiently close proximity to each other to avoid producing a reducing atmosphere at the location. At least a portion of the produced CO.sub.2 and steam are recycled to the reactor.

A feed injector for a circulating fluid bed reactor is fitted with a discharge nozzle with a circular, radially notched discharge orifice to improve the surface-to-volume ratio of the spray pattern formed by the nozzle. The feed injector is useful for injecting fluids into various types of circulating fluid bed reactors in which good contact between the components of the fluidized bed and the injected fluid is required. It is particularly useful in fluid coking reactors.

A reactor for hydrocarbon fuel is provided. The reactor uses interconnected fluidized beds (IFB) in chemical-looping combustion for multi-stage reduction reactions of an iron-based oxygen carrier, namely hematite (Fe.sub.2O.sub.3). Three-phase reduction reactions of Fe.sub.2O.sub.3 are accurately and completely controlled. The three-phase reduction reactions are separately processed while oxygen in Fe.sub.2O.sub.3 is fully released. Carbon dioxide with high purity is further obtained while hydrogen can be generated as a byproduct under a certain condition. Hence, the present invention has fast throughput, high-efficiency operation and low cost.

The invention is in the technical field of bubbling fluidized bed combustion and relates to the use of ilmenite particles with an average particle size <dp> between 0.1 mm and 1.8 mm as bed material for a bubbling fluidized bed (BFB) boiler with an excess air ratio () below 1.3 and to a method for operating a bubbling fluidized bed (BFB) boiler, comprising carrying out the combustion process with a bubbling fluidized bed comprising ilmenite particles as defined in any one of claims 1 and 4-5; and setting the excess air ratio () to a value below 1.3.

The invention is in the technical field of bubbling fluidized bed combustion and relates to the use of ilmenite particles with an average particle size <dp> between 0.1 mm and 1.8 mm as bed material for a bubbling fluidized bed (BFB) boiler with an excess air ratio () below 1.3 and to a method for operating a bubbling fluidized bed (BFB) boiler, comprising carrying out the combustion process with a bubbling fluidized bed comprising ilmenite particles as defined in any one of claims 1 and 4-5; and setting the excess air ratio () to a value below 1.3.

A device for chemical looping combustion of a fuel, operating in the liquid phase and including: a tank receiving a liquid including an oxidizing agent and a reducing agent, an oxidation loop including: a first conduit, a first device for injecting a first motor fluid including dioxygen, configured for introducing the first motor fluid into the first conduit, and a first separating device for separating the first motor fluid from the liquid and for sending the liquid to the tank, a reduction loop including: a second conduit, a second device for injecting a second motor fluid including a fuel that includes carbon, configured for introducing the second motor fluid into the second conduit, and a second separating device, configured for separating the second motor fluid from the liquid.