Evaluating Pulse Jet Mixing With Non-Newtonian Slurries

Abstract

Pulse jet mixer technology has been selected for implementation in the Hanford Waste Treatment Plant. However, processing non-Newtonian fluids using this technology is not mature. Experiments were conducted at several scales to develop an understanding of the scaling mechanisms that govern this type of mixer performance.

An Approach to Understanding Cohesive Slurry Settling, Mobilization, and Hydrogen Gas Retention in Pulsed Jet Mixed Vessels

“…Many of the studies focused on quantifying mixing behavior and performance (Bontha et al 2000(Bontha et al , 2003a(Bontha et al , 2003bEnderlin et al 2003;Johnson et al 2003;Bates et al 2003;Bamberger et al 2005;Meyer et al 2005;Johnson et al 2005;Poloski et al 2005;Bontha et al 2007;, and other studies focused on gas retention and release, but also provided improved understanding of PJM mixing performance (Stewart et al , 2006a(Stewart et al , 2006band Russell et al 2005). These previous PJM studies were conducted with non-Newtonian simulants that did not settle, but they still provided a significant basis for understanding and estimating the performance of PJMs for mobilizing settling layers of cohesive materials.…”

“…In the study by Bamberger et al (2005), the mechanism of cavern breakthrough due to upwelling in the center of a ring of PJMs was described, and testing results at multiple velocity scales with a range of simulants were reported. The general configuration of cavern breakthrough is depicted in Figure 4.2.…”

“…Bamberger et al (2005) reported results for cavern breakthrough for PJM tests with a range of clay mixtures and vessels. For determining an estimate for C, the test results for a mixture of kaolin and bentonite clays conducted in the 336 Large-Scale 4PJM Test Stand are used because this clay mixture was the most realistic simulant, and the test stand was the largest used.…”

“…For determining an estimate for C, the test results for a mixture of kaolin and bentonite clays conducted in the 336 Large-Scale 4PJM Test Stand are used because this clay mixture was the most realistic simulant, and the test stand was the largest used. Table 4.1 shows the parameters and specific test data from various sources in Bamberger et al (2005). The test data reported Re τ when breakthrough just occurred from central upwelling, which is Mode 2 mixing as shown in Figure 5.1 of Bamberger et al (2005).…”

“…These studies did not consider waste materials where the materials in the tank could segregate into a settled layer with non-Newtonian properties below a liquid layer with Newtonian properties. Numerous other studies have investigated PJM mixing performance, but with the exception of the earliest study by Bontha et al (2000), these studies also focused on vessels filled with non-Newtonian slurries that did not settle (Bontha et al 2000(Bontha et al , 2003a(Bontha et al , 2003bEnderlin et al 2003;Johnson et al 2003;Bates et al 2003;Bamberger et al 2005;Meyer et al 2005;Johnson et al 2005;Poloski et al 2005;Bontha et al 2007;). Accordingly, additional understanding is needed for PJM mobilization of settled cohesive layers, including the role of important parameters, such as the shear strength and height of the settled layers, to allow the quantitative prediction of the gas retention and release from these layers.…”