A grate arrangement and a method for use in a fluidized-bed boiler. The arrangement comprises a grate having length and width defining the area of said grate, plurality of gas feeding means being distributed on the area of the grate, a gas supply system connected to the plurality of gas feeding means for supplying fluidizing gas above the grate, and a booster gas supply system connected to at least some of the plurality of gas feeding means for supplying booster gas above the grate. The gas feeding means are grouped in at least two feeding groups, each of which feeding groups is extending only to a subarea of the area of the grate. Controlling means are arranged for controlling the systems so that while at least one of the feeding groups is open to the gas supply system for feeding fluidizing gas above the grate, at least one another of the feeding groups is closed to said gas supply system and open to the booster gas supply system.

A grate arrangement and a method for use in a fluidized-bed boiler. The arrangement comprises a grate having length and width defining the area of said grate, plurality of gas feeding means being distributed on the area of the grate, a gas supply system connected to the plurality of gas feeding means for supplying fluidizing gas above the grate, and a booster gas supply system connected to at least some of the plurality of gas feeding means for supplying booster gas above the grate. The gas feeding means are grouped in at least two feeding groups, each of which feeding groups is extending only to a subarea of the area of the grate. Controlling means are arranged for controlling the systems so that while at least one of the feeding groups is open to the gas supply system for feeding fluidizing gas above the grate, at least one another of the feeding groups is closed to said gas supply system and open to the booster gas supply system.

To improve operational efficiency by effectively utilizing produced carbon dioxide in a chemical loop reaction system, a chemical loop reaction system 100 includes an oxidation column 10 to oxidize metal particles M into metal oxide particles MO, a reduction column 20 to react the metal oxide particles MO with a reducing agent R to reduce the metal oxide particle MO into the metal particles M while producing carbon dioxide, and a circulator 60 that circulates the metal particles M and the metal oxide particles MO between the reduction column 20 and the oxidation column 10 and includes a carbon dioxide supply line 70 that supplies the carbon dioxide produced in the reduction column 20 to at least one of the reduction column 20 and the oxidation column 10.

To improve operational efficiency by effectively utilizing produced carbon dioxide in a chemical loop reaction system, a chemical loop reaction system 100 includes an oxidation column 10 to oxidize metal particles M into metal oxide particles MO, a reduction column 20 to react the metal oxide particles MO with a reducing agent R to reduce the metal oxide particle MO into the metal particles M while producing carbon dioxide, and a circulator 60 that circulates the metal particles M and the metal oxide particles MO between the reduction column 20 and the oxidation column 10 and includes a carbon dioxide supply line 70 that supplies the carbon dioxide produced in the reduction column 20 to at least one of the reduction column 20 and the oxidation column 10.

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.

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.