Correlation of input pressure fluctuations and fluidized bed structure

The objective of this study is to demonstrate the relationship between reactor inlet pressure fluctuations and the spatial structure of a fluidized bed using a 50,000 t/year wastewater sludge oxidation reactor as an example. A tubular collector is used to fluidize the bed in the reactor, for which similar data are not available in the literature. The study was conducted using three-dimensional numerical modeling. Inlet pressure monitoring data and reactor bed video recordings were used for comparison with calculations. It is shown that pressure fluctuations at the reactor inlet and at various points along the bed height correlate, with the degree of correlation decreasing with distance from the reactor inlet. Spectral analysis of inlet pressure fluctuations revealed a coincidence of the main oscillation frequencies in the range of 0.8–1.0 Hz in both calculations and experiments. A comparison of the bed surface dynamics between calculations and experiments revealed that the process of large bubble formation, which underlies the hydrodynamic pattern in the bed, is similar in both calculations and experiments. Information on the degree of correlation between inlet pressure variations and the fluidized bed structure is useful for determining the current state of the catalyst bed, which contributes to reliable control of the reactor and the process as a whole.