Flow Simulation and Identification of Important Model Parameters in Industrial Packed Beds for High-Performance Random Packings

The goals of this work were: first, to simulate the liquid flow distribution in a large diameter (1.2 m) packed column with an RMSR 70-5 high performance random packing (layer height up to 3 m), by a dispersion model. Second, to find and estimate the important model parameters and flow maldistribution factor, using experimental data and two different optimization approaches. A three-parameter dispersion model for prediction of radial liquid distribution and two different approaches to determine some of the model parameters from experimental data were used. In parallel, a two-parameter optimization procedure for model parameters identification was performed based on the minimum of residual variance between model and experimental liquid velocities over a column crosssection. The simulated and experimental flow maldistribution, were estimated by means of an integral estimation – a maldistribution factor. The comparison between the model and experimental liquid distribution and respective maldistribution factors at packing heights H = 1 m and H = 2.5 m for liquid load 16.6∙10-3 m3/m2∙s showed very good agreement, even for a high packing layer. In conclusion, the presented model predictions and estimations about RSRM 70-packing 5 characteristics and behaviour will complement the information about its efficiency and operation in industrial processes

LOCAL VELOCITY AND SHEAR DEFORMATION RATE AT MODEL MEMBRANES IMMERSED IN A BIOREACTOR AGITATED BY CURVED-BLADE IMPELLER: THE EFFECT OF MEMBRANE POSITION

A stirred bioreactor equipped with two submerged tubular membrane modules and curved-blade, backswept (BS) impellers is studied. The membranes are positioned in different parts of the vessel, a subsurface and a bottom one. The flow conditions at the membranes for effective fouling control are targeted. Contemporary CFD methodology is applied. The zones of major importance for effective operation of the membranes are examined and the values of hydrodynamic parameters are revealed. In these zones, the local velocity and shear parameters’ distributions are determined. The flow parameters are correlated with impeller rotational speed and fluid viscous properties. Angular velocity is varied between 600 and 1100 rpm and bulk viscosity is varied between 1 and 60 mPa s. The role of aeration is specified. The maximum shear rates at the membrane interface are registered. The corresponding stress force imposed by the BS impellers is compared with the one generated by conventional flat- blade Rushton turbine (RT). The hydrodynamic data are compared with reference data from the literature and the possibility for effective operation non-damaging for living micro-organisms is discussed

Studying the process of freons mixture separation on a structured packing Sultzer 500X

Structured packings are widely used in distillation columns to separate various types of mixtures. These packings have an ordered structure, which ensures more uniform conditions for interaction of counter-current flows of liquid and vapor than in the random packings and have a small hydraulic resistance. Nevertheless, in columns with a diameter of more than 0.5 m, formation of large-scale non-uniformity in distribution of liquid and vapor flow parameters over the packing cross-section is observed. In this work, experimental data on formation of large-scale non-uniformity in the temperature field over the cross-section of the Sulzer 500X packing, as well as on the efficiency of mixture separation and the pressure drop across the packing were obtained. The experiments were carried out with separation of R114/R21 freon mixture on a 10-layer structured packing Sulzer 500X with a diameter of 0.6 m and a height of 2.2 m. Experimental data were compared with the results obtained earlier for a structured packing Mellapack 350.Y with a diameter of 0.9 m and a height of 2.1 m. The presented experimental data will be used to construct and verify a new model of mass transfer and efficiency of mixture separation in the large-scale distillation packed columns