An impedance probe for the measurements of liquid hold-up and mixing time in two/three-phase stirred tank reactors

A new probe based on the measurement of the electrical impedance has been d eveloped to measure liquid hold-up in gas/liquid, solid/liquid and gas/soli d/liquid stirred tank reactors. It allows measurements of liquid hold-up an d mixing time to be made in stirred tanks. The main advantage of the new pr obe is that it is absolutely non-intrusive, because it uses the shaft and t he baffles' support as electrodes, and that it can be used both for laborat ory scale reactors as well as for industrial stirred tank reactors. The rel ation between impedance and liquid hold-up under loading conditions closely follows the predictions made by means of the Bruggeman model. Therefore, t he new probe does not need any calibration, in that the liquid hold-up can be theoretically computed by the measurement of impedance.