Fluidized bed combustor distributor plate assembly

A fluidized bed combustor comprising:

• a combustion chamber;
• a distributor plate assembly at the bottom of said chamber, including a distributor plate with downwardly sloping surfaces;
• said surfaces having slots with vertically spaced shields thereabove to form laterally oriented air flow openings to said chamber to cause particle classification along said sloped surfaces;
• air flow riser tubes in addition to said shielded slots, projecting up through said surfaces to a position elevated thereabove, having air inlets at the bottom and outlets at the top;
• means for supplying forced air to said slots for the three purposes of classification, fluidization, and combustion, and to said risers for the two purposes of fluidization and combustion;
• and
• means for controlling classification of the fluidized bed independent from fluidization thereof comprising means for regulating the proportion of air flow to said slots with respect to the air flow to said riser whereby variation of the relative rate of air flow through said slots and said risers changes the classification relative to the fluidization of the fluidized bed.