Abstract: A method of feeding at least one of light, fine, volatile and moist fuel into a furnace of a circulating fluidized bed boiler. Fuel is introduced into the furnace and is combusted in the presence of a fluidized bed material to form flue gases. The fluidized bed material is circulated both inside the furnace in an internal circulation in which bed material returns along walls of the furnace down to the bottom of the furnace, and outside the furnace in an external circulation that includes at least a solids separator arranged in flow communication with the furnace. Bed material is separated from the flue gases in the separator. The flue gases are removed from the separator for further treatment. The separated bed material is returned to the furnace.

Abstract: An oxycombustion circulating fluidized bed reactor includes a reactor chamber and a gas distribution arrangement provided in a bottom section of the reactor chamber for introducing gas into the reactor chamber. The gas distributor arrangement includes a first gas feeding system and a second gas feeding system for introducing oxygen-rich gas into the reactor chamber. The first gas feeding system includes a first wind box and the second gas feeding system includes a second wind box. The first wind box has a common wall with the reactor chamber and the second wind box is arranged under the first wind box and has a common wall with the first wind box.