Chemical Engineering Science 62 (2007) 4304 – 4315 www.elsevier.com/locate/ces Integration of ECT measurements with hydrodynamic modelling of conventional gas–solid bubbling bed Yassir Makkawi , 1 , Raffaella Ocone ∗ Chemical Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK Received 13 July 2006; accepted 24 November 2006 Available online 8 December 2006 Abstract The electrical capacitance tomography (ECT) provides fast images of the cross-sectional concentration distribution of solid–gas flow in a confined volume. This information can be integrated with numerical simulation to estimate some of the most important hydrodynamic quantities in solid–gas flow, such as the particles velocity, interstitial gas velocity and particle–particle contact forces. In this study, using the two-fluid approach, momentum and energy balance equations, along with the appropriate boundary conditions, have been solved by integrating the numerical procedure with the experimental data of the fluidised bed pressure drop and pixel distribution of particle concentration available from the ECT measurements. Preliminary results of time-dependent hydrodynamic features of the bed are presented. These results were analysed and assessed using the available experimental literature data on conventional bubbling fluidised bed. In general, it is demonstrated that the integration of ECT measurements with numerical modelling offers a unique and promising technique for comprehensive non-intrusive information on gas–solid flow systems.  2006 Published by Elsevier Ltd. Keywords: Gas–solid flow; Bubbling bed; Electrical capacitance tomography; Hydrodynamic modelling 1. Introduction Despite the great advances achieved in measuring tech- niques for multiphase flows, a comprehensive reliable means for measuring the various hydrodynamic features in a gas–solid bubbling fluidised bed has been hampered by the lack of non-intrusive techniques. The main parameters required to quantify the fluidisation hydrodynamics are the particle con- centration, the particle velocity, the interstitial gas velocity, the granular temperature and particle–particle contact forces. Electrical capacitance tomography (ECT) represents a rela- tively new emerging and promising technique to measure the particle concentration, and its successful application in such measurements is well documented in the literature (Makkawi and Wright 2002, 2003, 2004; Pugsley et al., 2003; Jaworski and Dyakowski, 2001; Dyakowski et al., 1997). ∗ Corresponding author. Tel.: +44 131 451 3777; fax: +44 131 451 3129. E-mail address: r.ocone@hw.ac.uk (R. Ocone). 1 Current address: School of Engineering and Electronics, University of Edinburgh, Mayfield Road, Edinburgh, UK. 0009-2509/$ - see front matter  2006 Published by Elsevier Ltd. doi:10.1016/j.ces.2006.11.048 The objective of this study is to demonstrate the validity and potentials of integrating the ECT measurement with modelling to develop a tool to predict the hydrodynamics of a fluidised bed. Apart from particle image velocimetry (PIV), positron emission tomography (PET) and laser-Doppler anemometry (LDA), we are not aware of any other non-intrusive measur- ing technique, which can provide information on the particle velocity in a fluidised bed. Most recently, Process Tomog- raphy Ltd. (PTL) exploited the possibility of further devel- opment of the ECT system for advanced measurement in gas–solid flows. They developed new software (Tomoflow Flowan), which allows for particle velocity estimation by cross-correlating the signals produced by twin-plane ECT sen- sors. Since the early generations of commercial ECT systems, we also started to consider the possibility of improving the ECT system information by integration the ECT data with hydrodynamic modelling. This has the advantage over the PTL approach of providing reliable estimation of the particle velocity and comprehensive estimation of all the other hydro- dynamic variables discussed above. However, this approach is still in its early developmental stage and requires independent