Phase space structure and multi-resolution analysis of gas–solid fluidized bed hydrodynamics: Part I — The EMD approach

The Hilbert–Huang transform method, HHTM, is applied to perform a multi-resolution analysis by means of the empirical mode decomposition, EMD, of noisy pressure signals collected from a gas–solid fluidized bed operating in slugging regime. Several important dynamic components, such as local bubble, “bulk” and particle dynamics, are identified. The bulk dynamic component is used to estimate the bed expansion ratio and bed height. The Kolmogorov entropy, K, and the correlation dimension, D 2 , are used for monitoring slugging dynamics from the resulting bubble, particle and bulk time scales. To study the attractor structure, a method for elaborating return-maps, based on the join probability matrix, is used. It has been found that the bulk dynamics provides information of the global behavior of the dense phase and allows characterizing the slugging dynamics with correlation dimension 2.2 < D 2 < 2.6 . In contrast, the local bubble dynamics is characterized by a correlation dimension that ranges from 1.8 to 2.