CONTINUOSLY STIRRED TANK REACTOR PARAMETERS THAT AFFECT SLUDGE BATCH 6 SIMULANT PROPERTIES
[report]
J. Newell, D. Lambert, M. Stone, A. Fernandez
2010
unpublished
EXECUTIVE SUMMARY Significant differences in the physical properties of simulated wastes are observed depending on the preparation route selected. The preferred method for making simulant is by using a continuously stirred tank reactor (CSTR). There are several parameters that control the physical properties of the simulant. This work focuses on determining the effect of varying the parameters of pH, temperature, flow rate, and mixing speed during the simulant preparation for the purpose of
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... ng a simulant that is more prototypical of Savannah River Site sludge that is transferred to the Defense Waste Processing Facility (DWPF) for processing. A matrix was developed to establish the ranges of the parameters being investigated. Temperature was varied from 22-70 ºC, pH from 9-14, flow rate 30-250 ml/min, and mixing speed 350-1000 rpm. A series of 10 batches was made in the continuous stirred tank reactor (CSTR) using a sludge batch 6 composition. These batches were analyzed to determine the changes in particle size, rheology, and foaming. Data was analyzed using JMP statistical software to determine the aggregate effect of varying the parameters. By varying the parameters stated above for the precipitation process, the following effects and correlations were observed for the ten batches prepared: Particle Size Mean particle size ranged from 3-38μm and was consistent with previous simulants. Changes in pH, flow rate, and mixing speed are statistically significant with respect to particle size. The effect of flow rate and mixing speed are linear while that of pH is quadratic. Results indicated that a lower pH produces smaller particles. Rheology Increasing wt.% insoluble solids increases yield stress, as expected. Changes in pH, flow rate, temperature, and mixing speed are statistically significant with respect to yield stress. The effect of the tested parameters is linear. By varying the parameters tested, it appears that simulant yield stress could be adjusted to targeted value. Foaming Increasing mixing speed had a slight effect on increasing simulant foaming. Changes in pH, flow rate, and temperature had no effect on foaming. Recommendations The work performed for this study looked at four parametric effects for simulant SB6A. This resulted in 10 distinct batches for analysis. This was the least number of batches that could be prepared and still have the statistical ability to determine the individual effects of these parameters on the physical properties of simulant particle size, rheology, and foaming. For a more accurate correlation of the influence of these parameters, an additional 10 batches would need to be prepared and tested. SRNL is currently partnering with foam experts at the Illinois Institute of Technology (IIT). IIT will perform a study on simulants provided to them by SRNL. Their recommendations will be incorporated into a future test program.
doi:10.2172/983396
fatcat:cidabhzl4rcslbybf23r2tunfy