A TECHNIQUE FOR MEASUREMENT OF THE JET PENETRATION HEIGHT IN FLUIDIZED-BEDS BY PRESSURE SIGNAL ANALYSIS

Pressure fluctuations induced by gas discharge through an upward nozzl e in a fluidized bed have been studied with the objective of setting u p a new experimental technique for evaluating a characteristic length of the jetting region. Pairs of pressure signals were recorded simulta neously on the jet axis and at the bed side wall at the same distance from the distributor. The statistical analysis of the signals allowed the fluidized bed operating conditions to be associated with the chara cteristics of the signals in the frequency domain, and the characteris tic height of the jet to be determined. The analysis also supported th e evaluation of the jet height by means of direct comparison between t he fluctuations of static pressure on the axis and at the wall. The fe atures of the technique are discussed and compared with those of previ ously proposed techniques for measurement of the jet penetration lengt h. It was found that the characteristic height conforms with the defin ition of penetration length based on the concept of jet momentum dissi pation.