Interaction Between Gas-Liquid Jets and Fluidized Beds

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A fluidized bed occurs, under appropriate conditions, when one injects pressurized gas into a bed of small particles through a distributor. In fluidized beds, the particle-gas mixtures behave and can be handled like fluids - they flow, can be pumped, heated, used to mix or separate layers, and can operate continuously. Therefore, they are widely used in the oil, pharmaceutical, food and other industries. In many industrial fluidized bed reactors such as fluid catalytic cracking units, coaters and fluid cokers, the reactant feed is introduced into the system in the form of a gas jet or spray for different purposes. For example, bitumen is sprayed in the fluid coking process, which upgrades bitumen by means of thermal cracking. The liquid bitumen and steam are passed through a nozzle, atomized and injected horizontally into the reactor. The liquid bitumen coats the small solid particles (coke) and chemical reactions occur that produce the desired product. It is important to understand the physical phenomena that occur in the nozzle and in the fluidized bed in the vicinity of the nozzle in order to make sure the coating is uniform and no undesired agglomeration occurs. Agglomeration occurs often when liquid is sprayed into fluidized beds and an agglomerate of particles with liquid trapped inside forms. It can be a desired effect in certain processes, for instance in some pharmaceutical and food processing reactors, or undesirable as in the coking process. For all of these processes, it is important to have a good understanding of the interaction between the jets and the fluidized beds in order to understand the fluid distribution, mixing, coating and agglomerate formation and breakup. The applicant will investigate jet-fluidized bed interaction and will develop novel mathematical models that describe the process and enhance our understanding of the physical phenomena involved. The potential applications of the model to industry are widespread because they allow for process design and operational improvements that enhance the reactor efficiency and increase yield. Improved processes lead to energy savings and less impact on the environment.