Method and apparatus for combusting finely divided low sintering temperature fuel

Claim 1

FURNACE FOR COMBUSTING FINELY DIVIDED PARTICLES OF HIGH-ASH FUEL, WHICH PARTICLES RANGE IN SIZE FROM POWDER TO RELATIVELY COARSE SCREENINGS, SAID FURNACE COMPRISING: MEANS DEFINING A COMBUSTION CHAMBER; NOZZLE MEANS FOR INJECTING FUEL PARTICLES OF THE CHARACTER DESCRIBED, ENTRAINED IN COMBUSTION AIR , INTO SAID CHAMBER NEAR THE TOP THEREOF AND IN SUBSTANTIALLY EVEN DISTRIBUTION THROUGHOUT THE HORIZONTAL CROSS-SECTIONAL AREA OF THE CHAMBER; AN ASHPIT BELOW THE COMBUSTION CHAMBER AND IN COMMUNICATION THEREWITH; GRATE MEANS ABOVE THE ASHPIT AND BELOW THE COMBUSTION CHAMBER; MEANS FOR INTRODUCING COMBUSTION AIR INTO THE COMBUSTION CHAMBER FROM BELOW THE GRATE MEANS TO ENABLE THE SMALLEST FUEL PARTICLES INTRODUCED INTO THE COMBUSTION CHAMBER TO BE COMBUSTED IN SUSPENSION AND TO PROVIDE FOR COMPLETE COMBUSTION OF THE REMAINING PARTICLES ON A FUEL BED OF SUBSTANTIAL HEIGHT ON SAID GRATE IN THE COURSE OF DOWNWARD MOVEMENT OF SUCH PARTICLES FROM THE TOP OF SAID FUEL BED TO THE GRATE; AND A PLURALITY OF VERTICAL FINGER-LIKE COILS DISPOSED AT LATERALLY CLOSELY SPACED INTERVALS IN THE PORTION OF THE BOTTOM OF THE COMBUSTION CHAMBER ADAPTED TO BE OCCUPIED BY THE FUEL BED AND EXTENDING VERTICALLY SUBSTANTIALLY THROUGHOUT THE NORMAL FUEL BED HEIGHT OF THE COMBUSTION CHAMBER AND THROUGH WHICH COOLANT FLUID IS ADAPTED TO BE CIRCULATED IN INDIRECT HEAT EXCHANGE RELATION WITH FUEL IN ALL PARTS OF THE BED IN QUANTITIES AND AT A RATE SUFFICIENT TO MAINTAIN THE TEMPERATURE OF SUCH FUEL BELOW ITS SINTERING POINT.