Measurement of hydrodynamic data of gas-phase polymerization reactors using non-intrusive methods

The hydrodynamic characteristics of polyethylene resins are studied in deta il through a combination of different techniques in our laboratory. Compute r Assisted Tomography is used to determine voidage distribution under diffe rent operating conditions. Radioactive particle tracking is used to determi ne the solid particle trajectories, the horizontal and vertical velocities of the solids and the residence time distribution of the solids. X-ray fluo roscopy is used to determine bubble frequency and velocity. All these techn iques are then combined with the information obtained through monitoring pr essure fluctuations in the fluidized bed columns. All experiments are perfo rmed in Plexiglas columns of diameters that vary between 10 and 30 cm in di ameter. The materials used are polyethylene and air, respectively. The comb ination of these techniques provides the unique opportunity to study the fl uidized bed systems in great detail. Unfortunately, all techniques cannot b e implemented in a single experiment. As a result, the same experiment is r epeated as many times as necessary to collect the required data. The column is moved from one imaging system to the next and the experiment is repeate d under the same operating conditions. It is believed that the data collect ed can be used as if all the data were collected during the same test. This paper presents preliminary experimental results for each set of experiment s along with the nature and limitations of each set of experimental data. T he results from each different system are combined in an effort to describe the complex hydrodynamics of the bed. The incremental information obtained in each set of experiments compared to the macroscopic measurements (flow rate and pressure drop) is demonstrated. Crown Copyright (C) 2001 Published by Elsevier Science B.V. All rights reserved.