Nestor Cruz

Date of Award


Degree Type


Degree Name

Master of Engineering Science


Chemical and Biochemical Engineering


Dr. Cedric Briens

Second Advisor

Dr. Franco Berruti


This thesis presents research on the use of attrition nozzles in gas-solid fluidized beds for two applications: green sand reclamation and particle size control in fluid cokers. These two applications make use of the same attrition principles, and the main difference between them is that for green sand reclamation fragmentation is not desired, since its goal is just to remove an outer layer of the green sand particles. The green sand reclamation method proposed in this research is a new, innovative process while jet attrition is already used in fluid cokers. In addition to fluid cokers, other applications of

jet attrition in fluidized beds are in processes for the production of agricultural products, chemicals, carbon black, ceramics, minerals and metals, pharmaceuticals, cosmetics, pigments, resins and toners.

In the green sand experiments, the main objective was to determine the technical and economical feasibility of green sand reclamation using jet attrition in a gas-solid fluidized bed, and experimental results show that this proposed reclamation method may be technically and economically feasible if the green sand is calcinated prior to attrition.

In the particle size control experiments, the objective was to optimize the attrition nozzles that can be used in the fluid coking process to control the particle size distribution of the coke particles in order to maintain good fluidization. The main objective was to reduce the consumption of attrition gas. These nozzles are Laval type or convergent-divergent nozzles, and when modeling them, it was found that the original attrition nozzle has a geometrical shape that can be considered close to an optimum geometry. In addition to this, results show that grinding efficiency is correlated to the thrust produced by the supersonic nozzles.

Penetration of the gas jet created by the supersonic nozzles was studied using a set of triboelectric probes, and two correlations were presented: one that relates thrust with jet penetration, and another one that is a modification of a correlation that was proposed by Benjelloun et al. for the penetration of subsonic jets. These correlations agreed very well with the experimental data. Jet penetration studies are useful to avoid erosion of bed




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