CARPT technique

Fig. 15. Time-averaged streamlines and velocity vectors obtained by Devanathan el al. (1990) using the CARPT technique. (From Chemical Engineering Science, Volume 45, Devanathan, N., Moslemian, D., and Dudukovicz, M.R, Flow mapping in bubble columns using CARPT, pp. 2285-2291, copyright 1990, with permission from Elsevier Science.)...

Detailed reviews of the CARPT technique have been given by Devanathan et al. [51, 52], Moslemian et al. [142] and Sannaes [175] including the principles of operation, calibration and discussions of problems/difficulties related to this technique. A brief description of the set-up can also be found in the thesis by Sannaes [175]. Duducovic [55] presented a survey on the use of nuclear techniques to characterize opaque multiphase reactor flows, and Chaouki et al. [36] reviewed the non-invasive Tomographic and velocimetric techniques for monitoring multiphase flows. 

Larachi et al. (1996) applied their radioactive particle tracking technique to determine the time-averaged solids velocity in a three-phase fluidized bed. Techniques which are similar to CARPT, such as positron emission particle tracking and radioactive particle tracking, have been applied successfully to systems involving particulate solids. 

Recently, a novel hybrid radioactive particle tracking (RPT) facility has been developed where the calibration step for the radioactive particle was eliminated (Khane and Al-Dahhan, 2013). The new technique is claimed to minimize the dynamic bias associated with the original CARPT... 

The CARPT—CT techniques have been introduced at CREL to provide cold flow modeling information on slurry bubble column flows operated in chum turbulent regime needed for gas-to-Hquid conversion processes (Degaleesan, 1997 Degaleesan and Dudukovic, 1998 Degaleesan et al.. 

CARPT—CT techniques provide a unique tool for evaluation of holdup and velocity distribution in multiphase systems and for validation of CFD codes. A shared facility should be established. 

CARPT offers possibilities for mapping velocities and turbulence parameters for liquid and solids in bubble columns, ebulated beds, fluidized beds, slurry mixed systems, etc. It allows detection of stagnancies and assessment of distributor designs and column internals on flow pattern and mixing. The use of the technique in high pressure systems is feasible. 

Our understanding of the hydrodynamics of multiphase flows has progressed substantially in the recent three decades, thanks to the development of advanced experimental techniques, particularly laser Doppler anemometry (LDA), particle image velocimetry (PIV), computer-automated radioactive particle tracking (CARPT), and optical bubble probes. In addition, computational fluid dynamics (CFD) simulations allow for inner views in two-phase process equipment. 

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