DEVELOPMENT OF A ROTARY COMBUSTOR FOR REFIRING PULVERIZED COAL BOILERS

THE ROTARY COMBUSTOR (RC) IS BEING DEVELOPED TO REFIRE CONVENTIONAL PULVERIZED COAL BURNERS IN ORDER TO REDUCE SULFUR OXIDES (SOX) AND NITROGEN OXIDES (NOX) INUTILITY BOILERS BY MEANS OF COMBUSTION MODIFICATION. THE BURNER COMPRISES A SLOWLY REVOLVING, PERFORATED DRUM. GRANULAR COAL AND LIMESTONE ARE INTRODUCED INTO THE REVOLVING DRUM, WHERE THEY ARE FLUIDIZED AGAINST THEARTIFICIAL GRAVITY CAUSED BY CENTRIFUGAL (CENTRIPETAL) FORCE; THE COAL GASIFIES, AND SULFUR COMBINES WITH THE LIMESTONE IN THE NORMAL WAY. THE RESULTANT COAL GAS IS THEN PASSED THROUGH ADeNOX TUBE, WHERE THE FUEL NITROGEN IS FIXED, BEFORE BEING INTRODUCED INTO THE ORIGINAL COMBUSTION CHAMBER WITH FINAL (TERTIARY) AIR AND BURNED IN A CONVENTIONAL FLAME. THE RC IS INSTALLED ON THE BURNER WALL OF A CONVENTIONAL COAL BOILER TO REPLACE THE EXISTING BURNERS AND MILLING EQUIPMENT, THUS ELIMINATING THE POWER CONSUMPTION OF THE MILLS AND RAISING EFFICIENCY. LIMESTONE IS FED IN WITH THE COAL TO CAPTURE THE SULFUR WITHIN THE RC WHICH IS VERY EFFECTIVE AS THE TEMPERATURE RANGE OF THE ROTATING FLUIDBED IF CONTROLLED. THUS, SULFUR CAPTURE IN EXCESS OF 90% IS PREDICTED. THE RC INCORPORATES A COOLED FIRETUBE WITH SECONDARY AND TERTIARY AIR ADMISSION, THEREBY REDUCING NOX TO SIGNIFICNTLY LOWER LEVELS THAN CONVENTIONAL BURNERS. THE PHASE I OBJECTIVE IS TO DEMONSTRATE THE FEASIBILITY OF USING THERC BY ESTABLISHING THE DESIGN DETAILS AND COSTS, DEMONSTRATING MECHANICAL DETAILS ON A COLDMODEL, AND DEVELOPING THE DESIGN TO A PRACTICAL STAGE. THE DESIGN OF A UNIT TO TEST-FIRE ON A500 lbs/hr(COAL) COMBUSTIONRIG WOULD BE COMPLETED.