Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor(s)

Dr Cedric Briens and Dr Franco Berruti

Abstract

Liquid injections via spray nozzles are used in fluidized bed reactors such as Fluid Cokers. In such industrial processes, in order to maximize the product yields it is required to optimize the performance of the nozzle. Moreover parts of the bed might become defluidized, bogged, due to high liquid load. Then optimizing the performance of the nozzle and local bed bogging detection is the primary research objectives for this thesis work.

The first part of the research work was focused on developing a novel method employing electrical conductance to characterize the liquid distribution in a large scale fluid bed of about 7 tonnes of silica sand, using a commercial-scale spray nozzle. It was used to determine the effect of increasing atomization gas-to-liquid ratio on the liquid-solid contact efficiency. Electrodes have been employed to map the free moisture distribution through the entire bed. The results indicated that raising the G/L ratio improves the contact efficiency, especially at high G/L ratios.

The effect of a new device, consisting of a draft tube located downstream of the nozzle, on liquid distribution inside the large fluidized bed was studied next. It not only remarkably reduced the liquid trapped within wet agglomerates, but also greatly enhanced the distribution of injected liquid feed and the jet penetration of the nozzle.

Finally, the electrical conductance and several other experimental methods, such as differential and static pressure measurements, and image processing were successfully implemented to detect local bogging in a large scale pilot fluid bed.