Conference Dates

May 22-27, 2016


In the Fluid CokingTM process, heavy oil is contacted with hot fluidized coke particles. If the local concentration of liquid is too high, particles may stick together, resulting in poor fluidization or even defluidization, a condition commonly known as "bogging". Earlier studies, presented at Fluidization XIV, used capacitance sensors to show how bogging affects bubble properties and the distribution of liquid sprayed into a fluidized bed. The objective of this study is to identify other, more practical methods for early bogging detection.

Methods using pressure measurements or active sound transmission are presented. A Kolmogorov-Smirnov test of the wavelet coefficients of pressure fluctuations, optimised with a genetic algorithm, can detect early bogging more effectively than other methods using pressure fluctuations. A major advantage of this method is that its results are not affected by moderate variations in fluidization gas velocity. The success of this new bogging detection method is explained by studying the transmission of sound of different frequencies through dry and wet fluidized beds, which could also be used to detect bogging.

A theoretical model confirmed that the changes in bubble properties caused by bogging affect the transmission of sound through the fluidized bed. The geometry of the gas bubbles and their distance from the wall were measured with capacitance sensors to understand how bubble properties affect sound transmission. The propagation of sound with bubbles of various geometries was simulated with Comsol.