Fluidized bed combustion apparatus and method

An improved fluidized bed combustion apparatus having a combustion chamber adapted to provide a fluidized bed of particulate matter, including combustible fuel particles which are burned to support combustion, the fluidized bed being generally supported on a support member which is adapted to permit introduction of a fluidizing gas medium into the particulate matter and an inlet for introducing at least fresh combustible fuel particles into the fluidized bed, wherein the improvement comprises:

• a plurality of relatively dense bead-like particles made of a generally inert material, said bead-like particles being dispersed generally throughout the fluidized bed to act as a grinding agent to partially reacted particulate matter in the bed, said bead-like particles being adapted to be withdrawn along with other fluidized bed constituents for circulation through the heat exchange means and discharge back into the fluidized bed, said heat exchange means being generally separated from the combustion bed;
• and
• withdrawal means for withdrawing bead-like particles and other fluidized bed particles from the fluidized bed, said withdrawal means being located generally laterally distant from any location where particles are discharged back into the fluidized bed from the heat exchange means.

An improved method of carrying out fluidized bed combustion and transfer of heat generated from combustion of the fluidized bed, wherein the improvement comprises:

• providing for withdrawal of some particulate matter from the fluidized bed and causing the withdrawn particulate matter to flow through heat exchange means generally separated from the fluidized bed and back to the fluidized bed;
• and
• discharging withdrawn particulate matter leaving the heat exchange means in a generally horizontal direction over the fluidized bed, said particulate matter being withdrawn from the fluidized bed at a location generally laterally distant from where the withdrawn particulate matter is discharged from the heat exchange means, such that particulate matter discharged from the heat exchange means is generally unaffected by the withdrawal of particulate matter and tends to establish a circulatory influence on the fluidized bed.

An improved method of carrying out fluidized bed combustion of combustible particles within the fluidized bed, wherein the improvement comprises:

• providing a plurality of relatively dense bead-like generally inert particles dispersed generally throughout the fluidized bed to act as a grinding agent to partially reacted particulate matter in the bed, said bead-like particles being adapted to be withdrawn from the bed along with other fluidized bed particles for circulation through the heat exchange means;
• and
• discharging withdrawn bead-like particles and fluidized bed particles from the heat exchange means in a generally horizontal direction over the fluidized bed at a location which is generally laterally separated from any location where particles are withdrawn from the fluidized bed.