Mixing in SRS Closure Business Unit Applications

The following equipment is commonly used to mix fluids: mechanical agitators, jets (pumps), shrouded axial impeller mixers (Flygt mixers), spargers, pulsed jet mixers, boiling, static mixers, falling films, liquid sprays, and thermal convection. This discussion will focus on mechanical agitators, jets, shrouded axial impeller mixers, spargers, and pulsed jet mixers, as these devices are most likely to be employed in Savannah River Site (SRS) Closure Business applications. In addressing mixing problems in the SRS Tank Farm, one must distinguish between different mixing objectives. These objectives include sludge mixing (e.g., Extended Sludge Processing), sludge retrieval (e.g., sludge transfers between tanks), heel retrieval (e.g., Tanks 18F and 19F), chemical reactions (e.g., oxalic acid neutralization) and salt dissolution. For example, one should not apply sludge mixing guidelines to heel removal applications. Mixing effectiveness is a function of both the mixing device (e.g., slurry pump, agitator, air sparger) and the properties of the material to be mixed (e.g., yield stress, viscosity, density, and particle size). The objective of this document is to provide background mixing knowledge for the SRS Closure Business Unit personnel and to provide general recommendations for mixing in SRS applications