Feedstock injection system for fluidized bed combustor

Claim 1

A hydro/pressurized fluidized bed combustor comprising an upstanding shell having, at the bottom thereof, an entry port for low velocity entry of feedstock to said combustor, said feedstock including particulate solid material, steam and water; a pressurized hopper for said feedstock; a feedstock conduit communicating said entry port with said hopper, said feedstock conduit being surrounded, for at least a part of its length, by a heat exchanger; an upstanding, contoured entry conduit having a trumpet-shaped catenoid vertical cross-section gradually enlarging in an upward direction, said entry conduit being accommodated within the lower half of said upstanding shell and in communication with said entry port, said entry conduit being provided with a plurality of tuyeres in its peripheral wall; a jacket surrounding said entry conduit and in communication with a further jacket surrounding said entry port, said entry port jacket being provided with air and stream inlets; a fluidized bed in the upper portion of said entry conduit, for combustion of said feedstock; at least one in-bed cooling tube located in a combustion zone of said fluidized bed; at least one freeboard steam generation tube located above said combustion zone; and a weir located above said entry conduit and in communication therewith, said weir acting to extract ash from said fluidized bed at a rate which keeps the height of the bed constant within the combustor during operation thereof.