Abstract
In many industrial applications of gas-solids fluidized beds, the hydrodynamics of the bed can change over time, either by imposed alterations (e.g., a grade change) or by unwanted phenomena (e.g., agglomeration). In both cases, it is worthwhile to have an on-line monitoring method for detecting these changes quickly. In this paper, such a method, based on the short-term predictability of fluidized bed pressure fluctuations, is examined. Its sensitivity has been investigated by experiments with small step changes in the superficial gas velocity and by experiments with a gradual change in the particle size distribution of the solids in the bed. For both types of experiments, it is shown that the monitoring method detects changes in the excess gas velocity as small as 0.01 m/s. Furthermore, it is demonstrated that the method is well able to indicate if a stationary hydrodynamic state has been reached after a change in the particle size distribution (a ‘grade change’).
