Residence time distributions in a modular micro reaction system

Residence time distributions (RTDs) were investigated in a retention reactor (RR) and a coaxial heat exchanger (CHE) of a commercial modular micro reaction system, to improve processing time control and implement this system as a lab scale tool for thermal process development.RTD were investigated by step experiments (30 g/L NaCl solution against distilled water at 20 °C). Given a measured in- and outlet conductivity distribution where the outlet was produced by a convolution with a transfer function E(t), E(t) parameters (mean residence time θ and variance α2) were recovered using a computational routine.The flow in the RR remained close to a plug flow despite laminar conditions. Molecular diffusion was not sufficient to explain this improvement and further modeling would be required to clarify this behavior. The CHE showed a significant dispersion and θ two to five times longer than estimated, possibly due to flow defects associated to its complex geometry.

► Residence time distributions were studied in a reactor and a heat exchanger. ► The study was done with conductivity steps, NaCl solution against deionized water. ► A computational routine was used to find the mean residence time and the dispersion. ► Profiles were close to plug flow in the reactor but not in the heat exchanger. ► Hydraulic and mean residence times differed strongly in the heat exchanger.