The Study Of Liquid Distribution Morphology And Hysteresis Characteristics In A Trickle-bed Reactor

Trickle-bed reactor, which is a fixed bed of catalysts with cocurrent downflow of gas and liquid, is used extensively in the process of hydrofining and hydrocracking. The experimental work was conducted in a plexiglass column of 140 mm ID packed with glass beads of different diameters (1.9,3.6,5.2 and 9.3 mm) by applying air and water as the working system after the column was pre-flooded with high gas and high liquid flow rates to ensure complete wetting of the bed. The data acquisition of liquid holdup and pressure drop hysteresis loops was made possible by installation of pressure transducers and electrical capacity tomography (ECT).(1)From comparison of pressure drops between experiment and prediction, it showed that the Ergun's equation failed prior to the inception of pulsing flow, which means the gas-liquid interaction was already significant.(2)The experimental two-phase pressure drop was used for the calculation of gas relative permeability. It was found that the permeability of gas under various gas and liquid flow rates as well as different particle diameters was lower than 0.08 if pulsing flow was reached.(3) The proportion of film flow, cluster zone and gas zone was obtained by analyzing the experiment data in different operation condition using the parallel zone model. It is found that the proportion of single gas or cluster zone is much smaller than that of the gas-liquid zone when the gas and liquid flow rates are high. The proportion of gas zone decreases instead of increasing when the gas flow rate increases. But the proportion of gas-liquid area increases. It indicates there is a strong interaction between the liquid and gas. In the gas-liquid zone, the gas flow rate is bigger than the liquid flow rate. Meanwhile, the gas flow rate is always close to the superficial gas velocity.