1.  Field of the Invention
This invention relates, in general, to fluidized bed combustion and, in particular to a new and useful fluidized bed combustor which includes a coal supply gun assembly having a nozzle arranged to only discharge granular coal material between adjacent heat exchange elements of a heat exchanger assembly. 
In the operation of a pressurized fluidized bed combustor where the fluidized bed is cooled by a cooling fluid which is circulated through heat exchange tubes of the heat exchanger assembly which extends up into the bed, it is not unusual that these tubes must be examined and/or replaced during the lifetime of such devices.  The difficulty with the known construction is that even when the whole heat exchanger assembly, or any part thereof including its tubes, is easily removed through the bottom of the fluidized bed combustor's housing, a major shutdown of the combustor and a disassembly of a portion of the housing to facilitate removal and replacement and/or repair is still required and this is both costly and relatively time consuming.