ACOUSTIC EMISSION FEEDBACK FOR AUTOMATIC COAL-WATER SLURRY FUEL BOILER COMBUSTION CONTROL

MANY ADVANCES HAVE BEEN MADE IN COAL-WATER SLURRY FUEL (CWSF) BURNERS. THE POTENTIAL BENEFIT OF THIS METHOD OF BURNING COAL IS THAT THE BULK OF THE ASH AND SULFUR ARE REMOVED BEFORE THE COMBUSTION PROCESS, SUBSTANTIALLY REDUCING THE AMOUNT OF SULFUR DIOXIDE PRODUCED. ALSO, BECAUSE LESS EXCESS AIR IS NEEDED FOR THIS TYPE OF BURNER, THE EFFICIENCY OF THIS TYPE OF COMBUSION IS INCREASED. HOWEVER, THE PRESENT METHOD OF DETERMINING WHETHER THE OPTIMAL AIR-TO-FUEL RATIO IS ACHIEVED USES A ZIRCONIUM OXIDETRIM SENSOR. THIS SENSOR QUICKLY IS CLOGGED WITH ASH PARTICULATE AND BECOMES INACCURATE. PRELIMINARY ACOUSTIC EMISSION INVESTIGATION ON BURNERS HAS REVEALED AN APPARENT RELATIONSHIP BETWEEN THE BURNERS' EXCESS FUEL CONDITION AND THE ACOUSTIC SIGNATURE. THIS INVESTIGATION WAS DONE ON GAS- AND OIL-FIRED BOILERS. THIS PROJECT WILL BEGIN BY GATHERING ACOUSTIC DATA FROM THE CWSF BOILER AT PENN STATE UNIVERSITY, AND WILL PERFORM EXTENSIVE SIGNATURE ANALYSIS OFTHE SOUND AND WAVE FORMS MEASURED. ASSUMING THAT THE RESULTS OF THE ACOUSTIC ANALYSIS ARE SIMILAR TO THOSE FOR OIL- AND GAS-FIRED BOILERS, A BRASSBOARD DEMONSTRATION ACOUSTIC FEEDBACK SYSTEM WILL BE INSTALLED ON THE COAL-WATERSLURRY BOILER. THE TIP OF THE ACOUSTIC SENSOR WILL BE CONNECTED TO AN ALUMINUM OXIDE ROD EXTENDING INTO THE HOT REACTION ZONE OF THE COMBUSTION FLAME. THE CWSF BURNER WILLBE OPERATED FOR APPROXIMATELY A WEEK TO DETERMINE THE POTENTIAL FEASIBILITY OF THIS NEW METHOD OF COMBUSTION INSTRUMENTATION. INITIAL LABORATORY DATA SUGGEST THAT AN ACOUSTIC EMISSION SENSOR MAY LAST CONSIDERABLY LONGER THAN AZIRCONIUM OXIDE OXYGEN TEIM SENSOR. THE R&D LABORATORY AT PENN STATE HAS A ZIRCONIUM OXIDE SENSOR, AND IT WILL BE COMPARED ON AN ONGOING BASIS TO THE ACOUSTIC EMISSION TYPE SENSOR. THERE IS A SUBSTANTIAL AMOUNT OF SOFTWARE AND CONTROL LOOP INVESTIGATION TO BE DONE INVOLVING THE EXISTINGCONTROLLER NOW ON THE PENN STATE BOILER. THIS SOFTWARE WORKWILL BE ACCOMPLISHED CONCURRENT WITH THE ACOUSTIC SIGNATURE ANALYSIS; THIS SHOULD BE READY AT THE SAME TIME AS THE DEMONSTRATION.