Single-photon emission radioactive particle tracking method for hydrodynamic evaluation of multi-phase flows

P. Christian van der Sande*, Jack de Mooij, Evert C. Wagner, Gabrie M.H. Meesters, J. Ruud van Ommen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Evaluation of the hydrodynamics of opaque multi-phase flows remains a challenging task, with implications for various industrial processes such as chemical processing, pharmaceutical, and mineral processing. Understanding how design and operational variables affect the complex behavior of multi-phase flow systems is essential for optimizing processing conditions and improving efficiency. Radioactive particle tracking (RPT) has been a proven measurement technique to evaluate hydrodynamics in multi-phase flow systems. However, a limitation of the classical RPT technique exists in the assumptions made in the simulation of the count rate received by the detectors in correcting for varying flow-induced fluctuations in the volume fraction of the dispersed phase, often encountered in industrial multi-phase flow systems. In this paper, we introduce a fundamentally novel experimental RPT method that directly uses detected incident photon hit locations for the reconstruction of the three-dimensional radioactive tracer particle position. We argue that this approach is inherently more robust as varying attenuation does not affect the reconstruction. The RPT setup consists of three identical γ-radiation slit collimator detectors that are placed equidistantly at 120° intervals. A subsequent calibration-experimentation procedure is established that allows reconstruction of the tracer particle position with spatial accuracy and precision in the order of 1 mm. We demonstrate the applications of this technique in evaluating hydrodynamics in multi-phase systems by characterizing the flow field of industrial-grade polypropylene reactor powder in a laboratory-scale horizontal stirred bed reactor.

Original languageEnglish
Publication statusAccepted/In press - 2024


  • Granular flows
  • Horizontal stirred bed reactors
  • Hydrodynamics
  • Non-invasive monitoring
  • Radioactive particle tracking


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