Influence of temperature on fast-mode cyclic operation hydrodynamics in trickle-bed reactors

Abstract

Despite the merits of periodic operation praised in the academic literature as one of the process intensification strategies advocated for trickle-bed reactors (TBRs), there is still reluctance to implement it in industrial practice. This can partly be ascribed to the lack of engineering data relevant to the elevated temperature and pressure characterizing industrial processes. Currently, the hydrodynamics of trickle beds under cyclic operation, especially in fast mode at elevated temperature and pressure, remains by and large terra incognita. This study proposes exploration of the hydrodynamic behavior of TBRs experiencing fast liquid flow modulation at elevated temperature and moderate pressure. The effect of temperature and pressure on the liquid holdup and pressure drop time series in terms of pulse breakthrough and decay times, pulse intensity and pulse velocity was examined for a wide range of superficial gas and liquid (base and pulse) velocities for the air–water system. The pulse breakthrough and decay times decreased, whereas the pulse velocity increased with temperature and/or pressure. The pressure drop was attenuated with increasing temperature for a given superficial gas, and base and pulse superficial liquid velocities. Experimental pulse velocity values were compared to the Giakoumakis et al. [2005. Induced pulsing in trickle beds—characteristics and attenuation of pulses. Chemical Engineering Science 60, 5183–5197] correlation which revealed that it could be relied upon at elevated temperature and close to atmospheric pressure.