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Abstract
The stimulus response methodology was evaluated in an experimental study conducted to measure NaCl solution residence time distributions in a spouted bed dryer of inert particles. The influence of tracer volume, concentration, and injection mode upon the measured mean residence time and residence time distribution was determined following experimental design techniques. The injection mode showed no significant effect on residence times, whereas tracer volume and concentration had significant effects at the levels of 1 and 5%, respectively, under the conditions chosen initially. The steepest ascent and factorial design methods were applied to determine the range in parameters for optimum stimulus response. The procedure repeated for a polymeric paste showed similar results. However, the results also showed that care must be exercised when using the stimulus response technique and the optimum injection conditions must be determined. The procedure presented in this study may be adopted in future investigations of paste residence time distributions in spouted bed dryers of inert bodies.
ACKNOWLEDGEMENTS
Financial support from FAPESP (03/09447-6) and grants to the authors (IC/FAPESP and PQ/CNPq) are gratefully acknowledged.
Notes
Glass beads, dp = 2.6 mm, ρ = 2.50 g/cm3, ρb = 1.59 g/cm3, εmf = 0.387, Vmf = 117.1 cm/s.
∗Replicate of exp. 3
∗∗replicate of exp. 6
Condition 1: NaCl solution, H/Hmax = 0.44, V/Vms = 1.2.
∗Replicate of exp. 3
∗∗replicate of exp. 6.
Significance levels: ∗1%, ∗∗5%, ∗∗∗10%.
(Condition 1: NaCl solution, H/Hmax = 0.44).
Significance levels: ∗1%, ∗∗5%, ∗∗∗10%.
Condition 2: NaCl solution, H/Hmax = 0.66, V/Vms = 1.2; Condition 3: PC-01 dispersion, H/Hmax = 0.50, V/Vms = 1.3.
Condition 2: NaCl solution, H/Hmax = 0.66.
Condition 3: PC-01 blend, H/Hmax = 0.50.