Characterization of fluid dynamics of fluidized beds by analysis of pressure fluctuations

This paper reviews procedures for investigating the fluid-dynamic behavior of gas-solid fluidized beds using pressure signals as obtained from modeling or experiments. The procedures studied are applicable to all types of fluidized-bed reactor. Models generating pressure data in such systems are presented with respect to complexity and amount of information provided. There is a discussion on how a calculated pressure can be compared to a measured signal in order to create a reliable representation of the fluid dynamics of the system. The type of information resulting from various ways of measuring the pressure in fluidized beds is discussed, as well as the use of absolute versus differential pressure probes. Time series analysis is reviewed; it can be applied to modeled and measured pressure signals in time, frequency, time-frequency and state space. Also, recommendations are provided on the use of the methods of analysis examined. The sources of pressure fluctuations, propagation features and the nature of pressure waves in fluidized beds are discussed. Finally, examples from the literature are presented, illustrating the outcome of the procedures discussed. (C) 2007 Elsevier Ltd. All rights reserved.