LONGITUDINAL ACOUSTICAL RESONANCE MEASUREMENT OF PARTICLE LOADING AND SIZING IN GAS-SOLIDS FLOW

THE ACOUSTICAL RESONANCE MEASUREMENT PROVIDES A NONINTRUSIVE AND REAL-TIME MEASUREMENT OF MASS LOADING AND SIZING OF PARTICLES FLUIDIZED BY A GAS PHASE. THE SOUND SPEED OF A TWO-PHASE MIXTURE OF PARTICLES IN GAS DECREASES AS THE MASS DENSITY OF THE PARTICLES INCREASES. BY MEASURING THE DECREASE IN THE RESONANT FREQUENCIES, WHICH ARE LINEARLY RELATED TO THE SOUND SPEED, THE MASS DENSITY OFTHE PARTICLES CAN BE DETERMINED. BECAUSE THE SOUND SPEED IS DISPERSIVE WITH THE FREQUENCY OF THE ACOUSTICAL WAVES, THE FREQUENCY DEPENDENCE OF THE SOUND SPEED PROVIDES A METHOD OF DETERMINING THE PARTICLE SIZING BY MEASUREMENT OF THE FREQUENCIES OF DIFFERENT RESONANT MODES. FOR REALISTIC APPLICATIONS, A LONGITUDINAL RESONANCE IS REQUIRED FOR THE ACOUSTICAL RESONANCE MEASUREMENT. A FIRST ORDER ACOUSTICAL ANALYSIS OF THIS NONINTRUSIVE TECHNIQUE APPLIED TO LONGITUDINAL RESONANCES IS PROPOSED FOR THE CONDITIONS FOUND IN THE PNEUMATIC CONVEYANCE OF PULVERIZED COAL IN ELECTRICAL UTILITY POWER PLANTS. THE ANALYTICAL INVESTIGATION INCLUDES EVALUATION OVER THE FULL OPERATING RANGES OF THE PLANT. EXPERIMENTAL MEASUREMENTS ON A CLOSED LOOP TESTS LABORATORY SCALE TEST STAND AND AT A POWER PLANT ARE PROPOSED TO VERIFY THE TECHNIQUE. THE ANALYSES WILL BE USED TO INTERPRET THE RESULTS OF THE EXPERIMENTAL MEASUREMENTS.