Date of Award
Master of Engineering Science
Chemical and Biochemical Engineering
Dr. Lauren Briens
Dr. Cedric Briens
Dr. Franco Berruti
Experimental studies were conducted for monitoring fluidization quality, drying and nozzle spray stability in gas - solid fluidized beds of powders. The research focused on the development of triboelectric, acoustic emission and vibration monitoring methods as these can be reliably applied to a wide range of operating conditions at low cost and also often non - intrusively. In a small scale vibrated fluidized bed of powder, it was found that the minimum bubbling velocity and minimum fluidization velocity decreased with increasing vibration. This was because vibration aided in the breakup of inter-particle cohesive forces. Vibration also accelerated the drying of wet, fine and cohesive particles by breaking up wet agglomerates. Triboelectric probes were successfully used to monitor this drying and to determine the effect of vibration on the drying. Liquid injection into gas-solid fluidized beds has an adverse effect on bed fluidity. Acoustic and vibration measurements were extensively analyzed and correlated to bed fluidity through avalanche testing to successfully detect the bed fluidity of a large scale gas-solid fluidized bed. In addition, the acoustic and vibration measurements provided an indication of the time required to mix the solids after liquid injection into the bed. Spray stability is a critical factor when injecting liquid into gas-solid fluidized beds. The signals from an accelerometer placed on the conduit leading up to industrial nozzles were correlated to the spray stability in open air. However, when the nozzles were inserted into a large scale gas-solid fluidized bed the accelerometer signals were different. The mounting in the bed kept the nozzle assembly more stable, affecting the amplitude of the measured signal fluctuations but the effects of fluidization prevented direct calibration of spray stability in the bed to open air results. The accelerometer could still be used to evaluate the relative stability in the bed. In addition the accelerometer allowed the effects of gas properties and gas to liquid ratio on spray stability to be investigated.
Book, Garret, "MONITORING OF FLUIDIZATION QUALITY, DRYING AND SPRAY STABILITY IN A FLUIDIZED BED" (2010). Digitized Theses. 4201.