The local structure of gas fluidized beds —I. A statistically based measuring system

A system is described for measuring the parameters characterizing the local state of fluidization in beds of arbitrary sizes. This system is based on a miniaturized capacitance probe shaped so as not to disturb the local state of fluidization. Based on a statistical analysis of the signal, the mean bubble pulse duration, the number of bubbles striking the probe per unit time and the local mean bubble rise velocity are measured. The latter is measured by using the cross-correlation technique. From these parameters, further characteristics of the local state of fluidization are derived, in particular the local mean pierced length of bubbles, the local bubble volume fraction and the local bubble gas flow.