Positron emission particle tracking (PEPT): A novel approach to flow visualisation in lab-scale anaerobic digesters

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

Abstract

Positron emission particle tracking (PEPT) was used to visualise the flow patterns established by mixing in two laboratory-scale anaerobic digesters fitted with mechanical mixing or gas mixing apparatus. PEPT allows the visualisation of flow patterns within a digester without necessitating the use of a transparent synthetic sludge. In the case of the mechanically-mixed digester, the mixing characteristics of opaque sewage sludge was compared to a transparent synthetic sludge at different mixing speeds. In the gas-mixed apparatus, two synthetic sludges were compared. In all scenarios, quasi-toroidal flow paths were established. However, mixing was less successful in more viscous liquids unless mixing power was increased to compensate for the increase in viscosity. The robustness of the PEPT derived velocities was found to be significantly affected by the frequency with which the particle enters a given volume of the vessel, with the accuracy of the calculated velocity decreasing in regions with low data capture. Nevertheless, PEPT was found to offer a means of accurate validation of computational fluid dynamics models which in turn can help to optimise flow patterns for biogas production.

Details

Original languageEnglish
Pages (from-to)250-264
JournalFlow Measurement and Instrumentation
Volume54
Early online date24 Feb 2017
Publication statusPublished - 1 Apr 2017

Keywords

  • Anaerobic digestion , Mechanical mixing , Gas mixing , Flow patterns , Particle tracking