The mixing in two-phase gas-liquid and three-phase gas-liquid-solid system (turbulent bed contactor) is evaluated through residence time distribution (RTD) studies in terms of Peclet number. RTD experiments are conducted for various gas and liquid velocities, and number of stages for two- and three-phase systems. Since the mean residence time is very short in both the systems, a mixed flow tank with exponential decay RTD is used in series. After deconvolution, the RTD of the system is obtained. The experimental RTD curves are satisfactorily compared with the axial dispersion model and Peclet numbers are evaluated for all the experiments. The axial dispersion coefficients are calculated from Peclet numbers. With this study, it is thought that liquid phase mixing may be controlled by changing the quantity of solid particles in the bed. © 2005 Elsevier Ltd. All rights reserved.

P Sesha Talpa Sai

Department Of Chemical Engineering

A. E.R. Bruce

K. Krishnaiah

Axial flow

Fluidization

Multiphase flow

Tanks (containers)

Two phase flow

Axial Mixing

MULTIPHASE REACTORS

Residence time distribution

TURBULENT BED CONTACTOR

Mixing

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Chemical Engineering Science

Experimental data on liquid holdup are collected over a wide range of variables in a turbulent bed contactor (TBC) with a 3 mm projection of the gasket to block the free area of the distributor plate near the wall so that the channeling of liquid along the wall is avoided. The variation in dynamic liquid holdup based on static bed height ε ld,st with gas velocity, liquid velocity, particle diameter and density, static bed height, free-open area of the distributor plate and dimensions of downcomer are discussed for Type I and Type II turbulent bed contactor. Correlations are developed to predict the dynamic liquid holdup. The liquid holdup obtained through quick closing valve technique is compared with the liquid holdup obtained through residence time distribution (RTD) method. © 2003 Elsevier B.V. All rights reserved.

Chemical Engineering Journal

Liquid holdup in turbulent bed contactor

Liquid phase mixing in a turbulent bed contactor (TBC) is experimentally characterized through residence time distribution (RID) studies. A novel technique is employed to obtain the true exit tracer concentration and to increase the average residence time of the liquid. In this technique, an ideal mixed flow tank (MFT) is included in series with TBC. The RTD of the ideal MFT is deconvoluted from the RTD of the entire system to obtain the RTD of TBC alone. Using this method, the effect of gas and liquid velocities, static bed height, particle size and density, and number of stages on mixing of the liquid phase is studied. The experimental RTD curves are satisfactorily compared with axial dispersion model. Correlations are developed for predicting the Peclet number and the axial dispersion coefficient. It is observed in the present study that conditions close to plug flow of liquid phase can be achieved in multistage TBC. © 2004 Elsevier B.V. All rights reserved.

Characterization of liquid phase mixing in turbulent bed contactor through RTD studies

Axial mixing of the liquid phase in turbulent bed contactor (TBC) is studied through residence time distribution (RTD) experiments over a large range of variables such as flow rate of gas and liquid phases, static bed heights, diameter and density of particles and number of stages in presence of downcomer using air water system. Since all the liquid exits only through the downcomer, it enables the correct estimation of exit concentration of the tracer. The experimental RTD curves are satisfactorily compared with the axial dispersion model. The Peclet numbers evaluated by axial dispersion model and the Peclet numbers reported in the literature are used to propose a unified correlation in terms of operating and geometric parameters. Correlation is also developed for predicting the axial dispersion coefficient. It was observed in the present study that almost plug flow conditions can be achieved in multistage TBC. © 2003 Elsevier Ltd. All rights reserved.

Liquid phase mixing in turbulent bed contactor

The Canadian Journal of Chemical Engineering

Liquid-phase axial mixing study in a mobile bed contactor with low density particles

Chemical and Petroleum Engineering

Investigation of carryover in a column with trays of the downcomer type, having a large free cross section

Estimation of liquid phase mixing due to solids in a turbulent bed contactor

Journal	Chemical Engineering Science
ISSN	00092509
Open Access	No