Abstract: A circulating fluidized bed (CFB) system and method of operation provide for improved heat recovery. One or more return ducts from a particle separator attached to the combustion chamber have a heat transfer section with heat transfer surfaces. Low velocity fluidizing gas is introduced into a bed of particles having distinct heat transfer and particle transport sections to fluidize the bed, and transporting gas is separately introduced to transport a desired rate of particles from the bed to the combustion chamber through a solid particle inlet which is below the top surface of the bed of particles. Barriers are established which prevent the transporting gas from interfering with heat transfer in the heat transfer section.

Abstract: The present invention relates to a method and an apparatus for washing pulp according to which method the pulp is supplied onto a movable liquid-pervious support surface to form a substantially continuous layer; and washing liquid is supplied to the pulp layer and passed in several successive washing phases through different areas of the layer in such a way that the washing liquid gradually flows in the opposite direction compared with the flow direction of the pulp layer. According to the invention the washing liquid is divided in two or more partial flows which pass alternately through different washing phases in such a way that the washing liquid which in one phase has passed through the pulp layer flows past at least the washing phase preceding it in the flow direction of the pulp layer. The apparatus of the invention preferably includes a rotating cylinder having a casing surface of which serves as the liquid-pervious support surface for the pulp.