Improving Eductor Placement in a Tank Mixing Application

Customer Case Study

We were tasked with designing and positioning tank mixing eductors in such a way that stagnant areas would not occur.

About this Project: Purpose and Methodology

To ensure full blending of the liquid in a mixing tank, it's important to have constant movement throughout the tank domain. Moreover, minimizing mixing time saves overall production time and resources. Properly placing eductors involves careful consideration of the liquid's characteristics and the eductor's flow rate.

Our customer solicited our help in determining the proper eductor and placement in the tank to minimize mixing time and ensure adequate liquid blending.
First, we conducted a preliminary simulation to find the proper flow rate for the eductors. Thanks to the precision data we collect on each nozzle, this simulation was relatively straightforward. After setting these parameters, we generated and refined the mesh near the eductors and throughout the tank.

Finally, we set up the parameters of the simulation such as the turbulence model, physical properties of the liquids, eductor flow rates, process time steps, etc. This helped determine our final conclusion.

More about this Project: Solution and Insights

By capturing the velocity contours throughout the domain, we see movement and adequate mixing throughout the tank. Moreover, we observed this particular solution in vertical velocity contours, as opposed to the usual horizontal layout. This provides a better indication of the flow perturbation strength and the overall liquid blending. 
Finally, the path lines in this view gives an excellent perception of the overall mixing time throughout the domain. This provided our customer with a high-confidence estimate for how long it would take this eductor set-up to fully mix the liquid. In this case, a full and complete mixing would require about 4 hours. Our customer was very pleased with this result and the added insights.

Tank Mixing

CFD is a common optimization tool for tank mixing applications. The changing chemistry of certain liquids and the unique geometry of specific tanks makes CFD in ideal, time-saving solution for such applications.