Abstract
The liquid phase maldistribution factor has been investigated in trickle bed reactor, and the results are compared with the previous measurement data from literature by using the Electrical Resistance Tomography. The simulation results are in agreement with the experimental results to some degree. The flow rates and particle sizes have been simulated with the method of multiphase flow. There are two different particles with average diameters of 3.4 mm and 5.3 mm. The flow rate has been studied ranging from 100 ml/min to 1100 ml/min. It has been found that the changes of the particles and liquid flow rates have a significant impact on the distribution of the liquid volume fraction. The internal liquid holdup is more serious, and the wall-flow phenomenon is more obvious in a bigger flow rate. The prediction of the liquid volume fraction distribution is a key research technique. Regression predictions have also been researched on the section near outlet, which can predict the internal flow state of the trickle bed under the condition of high temperature and high pressure. The average liquid volume fraction is linear with flow rates. The maldistribution factor is the index correlation with the flow rates. The results and main conclusions can be used to predict the distributions and get the properties in a trickle bed reactor.
Highlights
En, Beni and Khosravi [5] made a research on the pressure drop and liquid holdup in high- and low-pressure tricklebed reactors based on CFD
Mcmanus et al [14] have investigated the distribution of only a single liquid phase under different flow rates in TBR by ERT. en, Eda et al [15] have investigated the gas-liquid flow distribution of spherical particles in the packed bed by ERT and found that the liquid flow rate has an influence on the radial diffusion of liquid phase
In order to find the distribution and property of liquid phase in TBR, a series of researches are taken based on both CFD and ERT. e distribution of liquid phase was studied with particles of different average diameters and a series of flow rates. e maldistribution factor is used to evaluate the impact factor in trickle bed reactor. en, the volume fractions of liquid phase have been predicted with CFD. e main conclusions are as follows: (1) e distribution of multiple phases was simulated for a TBR with a mixed model based on CFD
Summary
2.1. e eory of the Numerical Simulation. e simulation method in TBR mainly consists of two steps. En, a mixture model of multiphase flow is built to simulate the gas-liquid two-phase flow. En, the gas and liquid are set as continuous phases. E mass and momentum volume mean conservation equations for gasliquid phases are solved. E application of conservation equations for the mass and momentum is done by averaging the summing of the local instantaneous equilibriums in each phase [18]. K 1 e momentum conservation equation can be derived by summing the momentum equations of all phases It can be expressed as equation (6). E relationship between the drag force and mass transfer can be treated as closed terms to calculate the flow state of each phase in the multiphase flow and written as follows [19]: Fgl. where E1 and E2 are Ergun constants [19]. E1 is set to 1.5 and E2 is 1.75 in a normal simulation by experience. ρl and ρg are the liquid density and the gas density, respectively. ul and ug are the velocity of liquid and gas, respectively. dp is the diameter of the porous medium region. εl and εg are the liquid phase holdup and gas phase holdup, respectively. εs means the volume fraction of solid
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