Axial mixing in a large-scale packed extractor

Axial mixing in a large-scale packed extractor of 42.7 cm ID and 6-7.5 m packing heights was studied with n-hexane as the dispersed organic component and city water as the continuous phase. Three types of packing were used: Koch SMV32 structured, 108 sq m/cu m specific surface area, and 0.98 void fraction; Koch SMVP32 structured with intermediate plates (50% open area), 108 sq m/cu m specific surface area, and 0.98 void fraction; and Koch SMVP16 structured with intermediate plates (50% open area), 220 sq m/cu m specific surface area, and 0.98 void fraction. To generate a sharp input signal, the continuous water phase in the column was spiked with a short impulse of 3 M NaCl solution. Probes were constructed to detect the salt concentration over the entire column cross section. The ″time domain fit″ was used to evaluate the data. Its basic function was to calculate the eddy diffusion coefficient and a phase velocity based on the measured input and output signals. Preliminary models were developed to predict the internal continuous phase velocity and the eddy diffusion coefficient.