A capacitance probe and a new model to identify and predict the capacity of columns equipped with structured packings

A new probe based on the measurement of the electrical capacitance has been developed to measure liquid holdup in columns equipped with structured pac kings. The main advantages of this new probe are that it is nonintrusive, i t allows fast and online measurements, and it can be used for laboratory-sc ale columns as well as for industrial applications. The probe is designed t o measure local liquid holdup and it can therefore be used to evaluate the presence of the liquid hold-up gradient inside each packing element in the column. Evaluation of the liquid hold-up gradient is helpful to identify lo cations inside the packing element where flooding begins and to suggest pac king design modifications. The relation between electrical capacitance and liquid holdup closely follows the predictions obtained using simple electri cal models. The experimental results obtained with the probe have enabled a simplified model to be tuned to predict capacity limits of columns equippe d with structured packings.