چكيده به لاتين
Abstract
Fluidized bed reactors have always been one of important process equipments in reactions or physical contacts between the gas-solid or solid-liquid phases and since these types of contacts or reactions in industry and the research are of the important fields of study, fluidized beds are always concerned by researchers.
In gas-solid fluidized bed reactors, gas phase is significant in both physical and chemical point of view. The most important factor in increasing the efficiency is to increase contact area between gas and solid phase. Therefore converting the gas phase into bubbles and their flow through the solid phase is a suitable solution to increase the contact area. Thus bubbles and their properties and hydrodynamics are important.
In present work two types of particles with different densities and different sizes have been chosen that both types of particles are of Geldart D. Some experiments are designed to investigate some properties of bubbles in fluidized bed, included bubbles diameter and center of mass in formation times, detachement time, aspect ratio and gas leakage from bubbles to emulsion phase.
After carrying out the experiments and recording the desired process by video camera, to extract necessary data from recorded videos, method of image processing was used.
Finally, after extracting the data related to above-mentioned parameters, the analyses were done. The results of analyses showed that at the time of bubbles formation, the bubble diameter is proportional to the 0.54-0.58 power of time for all densities and sizes. Bubbles center of mass at the formation moment is proportional to the second power of time. It was observed that the detachement time of bubbles did not change by differences in particle size but it had a little change with changes in density. Bubble aspect ratio curves showed that by decreasing the particles density and increasing particles size, the bubbles aspect ratio increased. Parameter was used to analyse gas leakage and that was concluded that gas leakage decreased by increasing the particles density and it increased by increasing particles size.
Key words: Fluidized bed, image processing, Bubble properties
