Patent ID: 7194983

Claim:
A circulating fluidized bed boiler, comprising a furnace, a separator connected to the furnace to separate fluidized bed material from a flow leaving the furnace, a return duct between the separator and the furnace to return the separated fluidized bed material into the furnace; said return duct comprising a loop seal comprising a heat exchanger chamber comprising a heat exchanger, a bottom, walls and a closed top defining the chamber, a supply of fluidizing medium, an inlet and an outlet, which open into said heat exchanger chamber, and are situated at different heights, the outlet being connected through a return conduit to the furnace; said inlet providing an inlet direction for an inlet flow of the fluidized bed material and a flow cross-section area for the fluidized bed material, and said outlet providing a flow cross-section area of a horizontal dimension for the fluidized bed material; whereby the flow cross-section area of the outlet is at an angle to the flow cross-section area of the inlet in such a way that the fluidized bed material is transferred in the heat exchanger chamber in lateral direction with respect to the inlet direction of its inlet flow; the heat exchanger chamber further comprising individually controllable fluidizing means at different locations in the direction of the horizontal dimension of the flow cross-section area of the outlet, and an outlet chamber arranged adjacent to the heat exchanger chamber, the outlet chamber comprising a bottom, wherein the return conduit exits from the outlet chamber, and wherein the outlet chamber is connected through said outlet to the chamber comprising the heat exchanger.