Fluidized bed combustor with improved indirect heat exchanger units

A fluidized bed combustor comprising:

• (a) an insulated combustion chamber comprising an upper interior portion and a lower interior portion and having an interior surface and a removable lid, said lower interior portion for containing a fluidized bed of combustible particulate carbonaceous fuel;
• (b) a fluid inlet conduit extending from at least the lid downwards into said upper interior portion of the combustion chamber;
• (c) a fluid inlet manifold contained within the upper interior portion of and adjacent the interior surface of the combustion chamber, said fluid inlet manifold secured to and in flow communication with said fluid inlet conduit;
• (d) a fluid outlet conduit extending from within the upper interior portion of the combustion chamber at least to said lid;
• (e) a fluid outlet manifold contained within the upper interior portion of and adjacent the interior surface of the combustion chamber, said fluid outlet manifold secured to and in flow communication with said fluid outlet conduit;
• (f) a first intermediate manifold secured to the lid and contained in the upper interior portion of the combustion chamber adjacent the interior surface thereof and substantially parallel to said inlet and outlet manifolds;
• (g) a second intermediate manifold secured to the lid and contained in the upper interior portion of the combustion chamber adjacent the interior surface thereof and positioned substantially parallel to said inlet and outlet manifolds;
• (h) an economizer contained in the upper interior portion of said combustion chamber and formed of a plurality of first indirect heat exchange conduits and second indirect heat exchange conduits alternately spaced from the first indirect heat exchange conduits in substantially parallel relation, said first indirect heat exchange conduits coupled in flow relation to said fluid inlet manifold and said first intermediate manifold, said second indirect heat exchange conduits coupled in flow relation to said fluid inlet manifold and said second intermediate manifold;
• (i) a plurality of first downcomers coupled in flow relationship to and extending downwards from said first intermediate manifold adjacent the interior surface of the combustion chamber and into the lower interior portion thereof;
• (j) a plurality of second downcomers coupled in flow relationship to and extending downwards from said second intermediate manifold adjacent the interior surface of the combustion chamber and into the lower interior portion thereof;
• (k) a plurality of third indirect heat exchange conduits alternatively spaced from a plurality of fourth indirect heat exchange conduits in substantially parallel relation, the third and fourth heat exchange conduits suspended within the lower interior portion of said combustion chamber in spaced relation to the interior surface thereof, the third heat exchange conduits coupled in flow communication to said first downcomers and by first risers to said fluid outlet manifold, said fourth heat exchange conduits coupled in flow communication with said second downcomers and by second risers to said fluid outlet manifold;
• (l) means for introducing a particulate carbonaceous fuel to said lower interior portion of the combustion chamber;
• (m) means for introducing air to said lower interior portion of said combustion chamber.