May 23, 2017

Shyam Sundaram, Allan Issangya,  S.B. Reddy Karri, R.A. Cocco, T.M. Knowlton, B.Freireic- 12th International Conference on Fluidized Bed Technology, Krakow, Poland

The internals in fluidized bed processes, such as heat exchanger tubes, are subject to forces which are due to bubble dynamics and particle motion. Understanding the nature of these forces are industrially important since erosion and excessive vibrations of the internals can lead to process reliability issues. Preliminary tests were performed using a dynamic force sensor in PSRI’s 2D fluidized bed unit (30-cm (12-in) wide by 2.54-cm (1-in) deep) with 760 μm size glass beads and 76 μm FCC equilibrium catalyst particles. The bed was at minimum fluidization and a single bubble was injected at different injection pressures. The sensor was mounted directly above a gas injection port used to inject a single bubble in the fluidized bed. Videos of the rising bubble and the response from the sensor were synchronized to quantify the forces from the bubble roof and wake. In the resulting waveform, the initial force caused by the injection of the bubble was the highest followed by lesser forces from wake and the roof. Tests were also conducted to quantify forces from gas jets, below and beyond the minimum fluidization velocity for the bed. There were two events that resulted in forces that were much larger than those observed from the rising bubbles. These random events, over a period, may be significant with respect to potential damage to fluidized bed internals.