0000000000061699
AUTHOR
Andrzej Burghardt
Hydrodynamics of a three-phase fixed-bed reactor operating in the pulsing flow regime at an elevated pressure
Abstract Results are presented for a three-phase reactor operating at an elevated pressure in the pulsing flow regime. For the system air–water and pressures of 0.1– 0.9 MPa lines are determined that define the change of the hydrodynamic model from the gas continuous flow regime (GCF) to the pulsing flow regime (PF). Also, parameters are found that characterize the pulsing flow of fluids, namely the velocity of pulses travelling along the bed, the frequency of pulsations and their structure, i.e., the length of the pulses and that of the liquid-rich zone.
The Application of CFD Methods for Modeling of a Three-Phase Fixed-Bed Reactor
The mathematical model of the three-phase fixed-bed reactor (TBR) consisting of the continuity equation, the momentum balances of each phase and mass balances of reaction mixture components were presented and discussed. These balances are the result of averaging by means of Euler’s procedure and form the basis of the Computational Fluid Dynamics (CFD). Although the CFD model is based on fundamental principles some empirical relations (closure lows) must be implemented into the momentum balance in order to ensure a proper description of the dynamics of very complex three-phase system. Therefore, the sensitivity of a multiphase CFD model with respect to relations defining drag forces between …
Influence of the porosity profile and sets of Ergun constants on the main hydrodynamic parameters in the trickle-bed reactors
Abstract The Eulerian multiphase code has been applied for the comparative simulation of the experimental results obtained for varying flow rates of both fluid phases and for systems of various physicochemical properties used in the laboratory trickle-bed reactor (TBR). Therefore six different radial porosity profiles and three sets of the Ergun constants used in the relations defining the interphase momentum exchange have been implemented into the CFD code. The mean relative error of the pressure drop and of the averaged holdup as well as the standard deviation determined with respect to the experiments have been used as the criterion for the validation of the theoretical model. These valu…
Parametric sensitivity of a CFD model concerning the hydrodynamics of trickle-bed reactor (TBR)
Abstract The aim of the present study was to investigate the sensitivity of a multiphase Eulerian CFD model with respect to relations defining drag forces between phases. The mean relative error as well as standard deviation of experimental and computed values of pressure gradient and average liquid holdup were used as validation criteria of the model. Comparative basis for simulations was our own data-base obtained in experiments carried out in a TBR operating at a co-current downward gas and liquid flow. Estimated errors showed that the classical equations of Attou et al. (1999) defining the friction factors Fjk approximate experimental values of hydrodynamic parameters with the best agre…
Analysis of the hydrodynamics of a periodically operated trickle-bed reactor—A shock wave velocity
Abstract The relationship describing the shock wave velocity was formulated for the trickle-bed reactor operating at periodically changed feeding the bed with liquid phase. The values of shock wave velocity calculated from derived equations were compared with experimental values obtained for both fast and slow mode of base–pulse periodic liquid feeding and using liquids differing in physicochemical properties. A good agreement between these two sets of values of shock wave velocity was obtained. It has to be emphasized that the relationship (Eq. (26) ) derived in this study enables to estimate the values of the shock wave velocity when only mean values of variables of a process are known.
Modelling wet-air oxidation of phenol in a trickle-bed reactor using active carbon as a catalyst
BACKGROUND Catalytic wet air oxidation (CWAO) of phenol in a trickle-bed reactor has been investigated (operating parameters: P=1.85 MPa, T=393, 413, 433 K, L=0.17–1.77 kg m−2 s−1 and G=0.2–0.62 kg m−2 s−1). Activated carbon was used as a catalyst. The experimental results have been simulated by Eulerian multifluid model (CFD) and for comparison by the plug flow model. RESULTS The experiments proved that active carbon can be applied as a catalyst in the phenol oxidation processes revealing a catalytic activity comparable with that of commonly used metal oxides. The highest conversion of phenol obtained in long-lasting experimental runs carried out at stable catalytic activity (PO2 = 0.31 MP…