Abstract submitted to ICOSCAR3 with the topic: Kinetics and transport phenomena in catalysts
PRESSURE DROP AND LIQUID HOLD-UP IN MULTIPHASE
MONOLITHIC REACTOR WITH DIFFERENT DISTRIBUTORS
XU Min, HUANG Hai, ZHAN Xiangpeng, LIU Hui*, JI Shengfu, and LI Chengyue
(State Key Laboratory of Chemical Resource Engineering，
Beijing University of Chemical Technology, Beijing 100029, China)
Objective
In the efforts to extend the application of monoliths to multiphase catalytic reaction systems, it
is stressed by many researchers that an even gas-liquid distribution across the channels of a
monolithic reactor bed is crucial for effective gas-liquid dispersion and contacting, thereby
ensuring a good reactor performance and facilitating reactor scale-up. In the current literature, it is
not quite clear as to the homogeneous flow distributor design of a monolith reactor. To address this
issue, we carried out experimental studies to ascertain the link between the multiphase
hydrodynamics of such bed and the configuration of the distributor.
Experimental
A co-current down-flow monolith reactor (D=10 cm; H=0.6m) was operated in the continuous
mode, using air as the gas phase and water as the liquid phase. Two types of distributors, i.e., a
commercial available spray nozzle and a bed packed with 1mm glass beads of 30cm high, were
adopted for a comparative study of their effect on hydrodynamics of monolith bed. Below the
distributors, four blocks of monolith (=9.5 cm; L=15m; channel diameters =1.1mm and 2.1mm,
respectively) were stacked as the reactor bed. Pressure drop and liquid hold-up measurements
were made with the superficial gas and liquid velocities covering a span of 0.055~0.388m/s and
0.039-0.118 m/s, respectively. In particular, the liquid hold-up was measured by a method of
weighting the liquid collected after simultaneous shutdown of the liquid and gas feed. In the
measurement, blank experiments were carried out in each case to obtain the net weights of liquid
within the monolith bed.
Major results
1) The total pressure drop of bed, consisting of the static and frictional parts, is sensitive to the
distributors and channel diameters of monolith. Both the static pressure drop and frictional
pressure drop are high for the glass beads bed distributor and 1.1mm diameter monolith, compared
with the nozzle distributor and 2.1mm diameter monolith, respectively. Negative pressure drops
were observed at low superficial gas velocities when the spray nozzle and 2.1mm diameter
monolith were installed.
2) Within the gas and liquid velocity range under which experiments were conducted, the
liquid hold up is found to vary from 0.1 to 0.6. The glass beads bed distributor and 1.1mm
diameter monolith have liquid hold up value, compared with the nozzle distributor and 2.1mm
diameter monolith, respectively.
3) A correlation for estimating the friction pressure drop and liquid hold up was developed and
was satisfactorily able to predict the experimental data obtained in this study. Besides, a criterion
for determining the occurrence of the negative pressure drops was proposed.
*
Corresponding author: LIU Hui. E-mail: hliu@mail.buct.edu.cn (H. Liu)