Comparison of Experimental Results to CFD Models for Blending in a Tank Using Dual Opposing Jets

Abstract

Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear,), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.

Comparison of Experiments to Computational Fluid Dynamics Models for Mixing Using Dual Opposing Jets in Tanks With and Without Internal Obstructions

“…The pH was monitored throughout these processes to understand the effects of bulk addition on blending. Various models were investigated to determine their effect on blending performance, and assist the parallel design of a centrifugal pump required for blending by SRS [1]. The four initial pilot scale pump models consisted of horizontal nozzles (Figs.…”

“…To do so, statistical analyses and engineering evaluations were performed to evaluate the variability of blending times, which were then used to establish a correction factor to be used with CFD models (Leishear, et al [1,6].…”

“…In short, this paper compares blending times calculated from Computational Fluid Dynamics (CFD) models to experimental results for pilot scale testing in a geometrically scaled, 2.44 meter (8 foot) diameter tank with sub-surface obstructions representing cooling coils, which were both installed and removed from the pilot scale tank during testing. The reader is referred to [1][2][3][4][5][6] for scale-up methods for blending times and other aspects of this blending research, which are specifically related to radioactive liquid waste processing. Developed from [1][2][3][4][5][6], this paper focuses on the blending of two fluids, which is applicable to the more general field of industrial mixing theory.…”

“…The reader is referred to [1][2][3][4][5][6] for scale-up methods for blending times and other aspects of this blending research, which are specifically related to radioactive liquid waste processing. Developed from [1][2][3][4][5][6], this paper focuses on the blending of two fluids, which is applicable to the more general field of industrial mixing theory.…”

“…A series of Conference papers summarize the full extent of this research (Leishear, et al. [1][2][3][4]), and Savannah River National Laboratory (SRNL) reports provide comprehensive experimental data and analysis from the research (Leishear, Lee, et al [5][6][7][8]). In short, this paper compares blending times calculated from Computational Fluid Dynamics (CFD) models to experimental results for pilot scale testing in a geometrically scaled, 2.44 meter (8 foot) diameter tank with sub-surface obstructions representing cooling coils, which were both installed and removed from the pilot scale tank during testing.…”