Investigating Jet Mixing Using Electrical Resistance Tomography

Abstract

Coaxial jet and side entry mixers are used in a wide range of industries for a variety of processes including precipitation, polymerization and neutralization duties. Jet mixers are characterized by short contact times between the fluids and can be operated continuously or semi‐batch. Coaxial and side entry jets can be designed in order to deliver rapid turbulent mixing using short sections of pipeline. As the energy required for mixing is provided by the addition stream, the process‐side pressure drop required for homogeneity is very low. A key design parameter for jet mixers is the mixing length, the length of pipe downstream of the injection point required to achieve a given degree of homogeneity. The mixing length can be affected by the addition geometry (for example coaxial or side entry), orifice size and shape, operating conditions and material properties. This paper presents the use of Electrical Resistance Tomography (ERT) to monitor jet mixing via the addition of a conductivity tracer through coaxial and side entry jets. Multiple ERT sensors are fitted along the pipe downstream of the jet addition point. The ERT sensors enable real time, non‐invasive measurement of conductivity within the pipe, furnishing approximately 2500 conductivity measurements per ERT sensor when modeled independently in 3D. The effect of secondary (main pipe) flow rate and jet configuration on the nature of the tracer plume evolution and axial mixing is determined using this technique.