WHILE PERFORMING TROUBLESHOOTING PROCEDURES ON FLUID BED DRYER, ORGANO DUST SUSPENDE IN FILTER SOCK, DISLODGED, CAUSING A DUST CLOUD OF PROPER CONCENTRATION TO SUSTAIN A FIRE. THE DUST CLOUD W AS IGNITED WHEN IT TRAVELED INTO THE COMBUSTION CHAMBER AND CAME IN CONTACT WITH SMOLDERING ORGANO CLAY THAT HAD BEEN HEATED BY COMBUSTION BURNER FLAME. A VALVE BETWN. COMBUSTION CHAMBER& DRY