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Open AccessFeature PaperArticle

Explicit Residence Time Distribution of a Generalised Cascade of Continuous Stirred Tank Reactors for a Description of Short Recirculation Time (Bypassing)

1
Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13, 8010 Graz, Austria
2
Worldwide Research and Development, Pfizer Inc. Groton, CT 06340, USA
*
Author to whom correspondence should be addressed.
Processes 2019, 7(9), 615; https://doi.org/10.3390/pr7090615
Received: 30 July 2019 / Revised: 22 August 2019 / Accepted: 5 September 2019 / Published: 10 September 2019
(This article belongs to the Special Issue Model-Based Tools for Pharmaceutical Manufacturing Processes)
The tanks-in-series model (TIS) is a popular model to describe the residence time distribution (RTD) of non-ideal continuously stirred tank reactors (CSTRs) with limited back-mixing. In this work, the TIS model was generalised to a cascade of n CSTRs with non-integer non-negative n. The resulting model describes non-ideal back-mixing with n > 1. However, the most interesting feature of the n-CSTR model is the ability to describe short recirculation times (bypassing) with n < 1 without the need of complex reactor networks. The n-CSTR model is the only model that connects the three fundamental RTDs occurring in reactor modelling by variation of a single shape parameter n: The unit impulse at n→0, the exponential RTD of an ideal CSTR at n = 1, and the delayed impulse of an ideal plug flow reactor at n→∞. The n-CSTR model can be used as a stand-alone model or as part of a reactor network. The bypassing material fraction for the regime n < 1 was analysed. Finally, a Fourier analysis of the n-CSTR was performed to predict the ability of a unit operation to filter out upstream fluctuations and to model the response to upstream set point changes. View Full-Text
Keywords: residence time distribution; continuous stirred tank reactor; bypassing; Fourier analysis; continuous manufacturing residence time distribution; continuous stirred tank reactor; bypassing; Fourier analysis; continuous manufacturing
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MDPI and ACS Style

Toson, P.; Doshi, P.; Jajcevic, D. Explicit Residence Time Distribution of a Generalised Cascade of Continuous Stirred Tank Reactors for a Description of Short Recirculation Time (Bypassing). Processes 2019, 7, 615.

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