Fluidized bed combustion system and a pressure seal valve utilized therein

A fluidized bed combustion system including a furnace;

• means for establishing a fluidized bed of combustible particulate material in said furnace;
• separating means for receiving a mixture of flue gases and entrained particulate material from said fluidized bed in said furnace and separating said material from said flue gases;
• pressure seal valve means for receiving said separated material from said separating means and establishing a pressure seal to prevent the backflow of said material from said furnace to said separating means;
• said valve means comprising a downflow leg connected to said separating means for receiving said separated material, first means for introducing air into the downflow leg, a lateral leg connected to said downflow leg for receiving said separated material, second means for introducing air into the lateral leg, an upflow leg connected to said lateral leg for receiving said separated material, a lateral overflow leg connected to said upflow leg for receiving said separated material and means for connecting said overflow leg to said furnace for discharging said separated material into said furnace.