Particle residence time measurements in a flash reactor
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(Published version)
Date
2023
Authors
Bi, X.
Lewis, E.
Nathan, G.
Sun, Z.
Editors
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Journal Title
Journal ISSN
Volume Title
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Conference paper
Citation
Proceedings of the Australian Combustion Symposium : Towards Clean Combustion and Decarbonisation (ACS2023), 2023, pp.126-129
Statement of Responsibility
X. Bi, E. W. Lewis, G. J. Nathan, and Z. Sun
Conference Name
Australian Combustion Symposium (26 Nov 2023 - 29 Nov 2023 : Darwin, Northern Territory, Australia)
Abstract
The particle residence time distribution, E(t), was measured in a lab-scale flash reactor for a pulse of particles added to a continuous jet issuing into a counter flow at room temperature. The measuring range is from the jet exit to two different downstream locations (x/dexit = 62 and 124) for a series of systematically varied initial flow conditions (𝑈j/𝑈c ≈ 31 – 636 for a constant 𝑈c = 0.008 m/s and 𝑈c/𝑈j ≈ 0.016 – 0.517 for a constant 𝑈j = 0.248 m/s, where 𝑈j is the jet flow velocity and 𝑈c is the counter flow velocity). The measurements were performed using light absorption of continuous laser beams positioned at the three aforementioned locations to allow the derivation of E(t) for the two measuring ranges both starting from the exit plane. The E(t) has been evaluated for the 1st and 60th percentiles, 𝜏p1 and 𝜏p,60, respectively, which characterise the leading edge and the bulk flow. It was found that the characterised particle residence time has a non-monotonic relationship with the normalised jet velocity, with the values of 𝑈 j/𝑈c for their (𝜏p,1 or 𝜏p,60) minimum values increasing as the x/dexit decreases. This is deduced to be associated with the effect of particle “group” reducing aerodynamic drag for bulk particles, while this effect can be minimised by sufficiently high jet velocity. Counter flow was found to broadly increase the particle residence time, although its effect is strong for downstream locations, while weak for the upper stream. Industrial-scale particle-based systems need to consider these different flow regimes to optimise design.
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2023
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© The Author(s) 2023. The copyright of the individual contributions contained in this volume is retained and owned by the authors of the papers. Neither Australian and New Zealand Section of the Combustion Institute nor Editors of Proceedings possess the copyright of the individual papers. Reproduction of all or part of this document, including storing in electronic form, is permitted, provided it is fully referenced.