A co-firing process is described using coal and processed biomass to reduce adverse by-products in a coal combusting apparatus. The coal feedstock is selected from coal, a coal substitute processed biomass, or an aggregate blend of coal and processed biomass. The biomass feedstock comprises processed biomass pellets. The total energy density is predetermined and can be similar to the coal component or higher than the coal component. The intracellular salt in the processed biomass is at least 60 wt % less for the processed organic-carbon-containing feedstock used to make the processed biomass pellets than that of the starting un-processed processed organic-carbon-containing feedstock.

A co-firing process is described using coal and processed biomass to reduce adverse by-products in a coal combusting apparatus. The coal feedstock is selected from coal, a coal substitute processed biomass, or an aggregate blend of coal and processed biomass. The biomass feedstock comprises processed biomass pellets. The total energy density is predetermined and can be similar to the coal component or higher than the coal component. The intracellular salt in the processed biomass is at least 60 wt % less for the processed organic-carbon-containing feedstock used to make the processed biomass pellets than that of the starting un-processed processed organic-carbon-containing feedstock.

A downward mobile gasification boiler for surface gas-phase combustion and pyrolysis of biomass briquette is provided. The boiler includes a gasification combustion chamber, a gas combustion chamber, a stranding cage slag remover, a heat exchanger, a water jacket, an air duct and an air distribution system. The air duct connected with the air distribution system is arranged in the inner cavity of the wall surface of the gasification combustion chamber. The gas combustion chamber is arranged at the upper part of the gasification combustion chamber, and an air outlet is arranged in the middle to communicate the gas combustion chamber with the gasification combustion chamber. The lower part of a port of the gasification combustion chamber is provided with a twisting cage slag remover.

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.