Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Chemical and Biochemical Engineering


Dr. Cedric Briens

2nd Supervisor

Dr. Franco Berruti

Joint Supervisor


In the Fluid Coking process, if the local concentration of liquid is very high, particles may stick together which can eventually result in process upset because of poor fluidization or even defluidization, a condition commonly known in industry as "bogging".

Using a capacitance sensor, the void distribution in a bed of coke particles can be visualized. The voidage fluctuations caused by gas bubbles have been shown to change dramatically as the bed becomes bogged. Therefore, capacitance sensors should be able to predict the bogging condition in fluid cokers.

The first part of the thesis focused on designing noiseless capacitance sensors that can be used to measure the liquid concentration and void distribution in a fluidized bed. The effect of bogging on the distribution of a liquid sprayed into fluidized bed was then investigated by determining the impact of bogging on the breakage rate of the liquid-solid agglomerates.

Pressure measurements are easier to perform in industrial units than capacitance measurements. The knowledge acquired with capacitance measurements was then applied to the design of early bogging detection methods from pressure measurements.

Detection of bogging with acoustic measurements is discussed in the next section. The speed of sound was measured at different levels of particles cohesiveness and fluidization velocities.

The last part of the thesis applies the capacitance sensors to the measurement of jet cavity fluctuations. Two types of jets were investigated: the supersonic gas jets and the jets formed when liquid is atomized with a gas into a fluidized bed.