Liquid holdup by gravimetric recirculation continuous measurement method. Application to trickle bed reactors under pressure at laboratory scale

Liquid holdup is a crucial parameter when operating catalytic trickle bed reactors related to wetting efficiency and residence time. Most of the classical methods are expensive, time-consuming, or not valid for high pressures. Liquid holdup by gravimetric recirculation (LHGR) measurement method determines the average total liquid holdup using a closed loop with total recirculation of liquid. The recirculating liquid is contained in a vessel that is weighed instantaneously with a known amount of liquid. The difference between the initial amount of liquid and the instantaneous weight gives the liquid holdup. Main benefits are the following: first, the measurement takes only the time of stabilization that at laboratory scale is 2–5 min; second, the system is ready for the next measurement without any modification (the bed is not disturbed nor modified); third, it works for high pressures; finally, it gives values comparable to those from classical techniques like RTD or conductivity methods.