A METHOD FOR THE REDUCTION OF DUST CAKE ADHESION IN CERAMIC FILER SYSTEMS

CERAMIC FILTRATION IS ONE OF THE MOST COST EFFECTIVE AND PROMISING TECHNOLOGIES FOR REMOVING PARTICULATS AT HIGH TEMPERATURES TO LEVELS EXCEEDING NEW SOURCE PEROFRMANCE STANDARDS (NSPS) ASWELL AS CLEAN AIR ACT MANDATES. WITH SUBMICRON RETENTION CAPABILITIES, CERAMIC FILTERS ARE IDEALLY SUITED FOR VIRTUALLY COMPLETE PARTICULATE AND SPENT SORBENT CAPTURE IN PRESSURIZED FLURIDIZED BED COMBUSTION AND COAL GASIFICATION SYSTEMS. UNFORTUNATELY, HOWEVER, SUCH COAL CONVERSION PROCESSES CAN PRODUCE COHESIVE PARTICULATES, BECAUSE OF THE PRESENCE OF TARS, CONDENSIBLES, OR FUSED ASH, OFTEN CAUSED BY TEMPERATURE TRANSIENTS. WITH ON-LINE JET PULSE CLEANING AS THE ONLY MEANS BY WHICH PARTICULATES ARE DISLODGED FROM A CANDLE FILTER, SUCH CONDITIONS CAN QUICKLY CREATE CEMENTITOUS FORMATIONS WHICH TEND TO "BLIND" THE FILTEERING SURFACE IRREVERSIBLY; UNDER SEVERE CONDITIONS, THIS CAN RESULT IN COMPLETE DESTRUCTION OF THE FILTER COMPONENTS. FORTUNATELY, A METHOD TO REDUCE PORE BLINDING AND ADHESION OF SUCH DUST CAKES COLLECTED ON CRAMIC FILTERS EXISTS THROUGH UTILIZATION OF BORON NITRIDE. STABLE IN BOTH OXIDIZING AND REDUCING ATMOSPHRES AT TEMPERATURES OF UP TO 2000 DEGREES FAHRENHEIT, BORON NITRIDE IS COMMERCIALLY USED AS A HIGH TEMPERATURE DRY LUBRICANT. PHASE I OBJECTIVS INCLUDE EFFORTS TO INVESTIGATE APPLICATION TECHNIZUES OF BORON NITRIDE TO COMMERCIALLY AVAILABLE SILCONCARBIDE AND ALUMINOSILICATE FIBER FILTERS, AS WELL AS TO INVESTIGATE THE FABRICATION OF A MONOLITHIC BORON NITRIDE FILTER CANDLE. COMPARATIVE TESTING OF THE BORON NITRIDE COATED ELEMENTS WITH UNTREATED ELEMENTS WILL BE CONDUCTED TO DETERMINE ANY PERMEABILITY CHANGES AND THE EXTENT OF DUST CAKE ADHESION REDUCTION, USING BOTH COAL GASIFICATION AND COAL COMBUSTOR DUST SOURCES, IN AN EXISTING TEST RIG; THE MONOLITHIC BORON NITRIDE FILTER CANDLE WILL UNDERGO SIMILAR TESTING AS WELL AS STRENGTH EVALUATIONS, FOR COMPARISON WITH COMMERCIALLY AVAILABLE FILTER ELEMENTS.