Experimental Flow Visualisation in a Modified Pulsed Baffled Reactor

Gough, P. E.; Ni, Xiongwei; Symes, K. C.

doi:10.1002/(sici)1097-4660(199707)69:3<321::aid-jctb717>3.0.co;2-q

Cited by 21 publications

(25 citation statements)

References 30 publications

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“…0.3Q R -0.6Q R ). These values of amplitude fall in the optimal operational range of amplitudes described in previous studies (Brunold et al, 1989;Gough et al, 1997;Soufi et al, 2017). The net flow and oscillatory Reynolds numbers corresponding to these conditions were in the ranges 6-27 and 24-96, respectively, ensuring axisymmetrical laminar flow since it is well below the transition to chaotic flow, i.e.…”

Section: Geometry and Operating Conditionssupporting

confidence: 55%

Predicting power consumption in continuous oscillatory baffled reactors

Avila

Fletcher

Poux

et al. 2020

Chemical Engineering Science

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Continuous oscillatory baffled reactors (COBRs) have been proven to intensify processes, use less energy and produce fewer wastes compared with stirred tanks. Prediction of power consumption in these devices has been based on simplistic models developed for pulsed columns with single orifice baffles several decades ago and are limited to certain flow conditions. This work explores the validity of existing models to estimate power consumption in a COBR using CFD simulation to analyse power density as a function of operating conditions (covering a range of net flow and oscillatory Reynolds numbers: !" #$% = 6 − 27 / !"-= 24 − 96) in a COBR with a single orifice baffle geometry. Comparison of computed power dissipation with that predicted by the empirical quasi-steady flow models shows that this model is not able to predict correctly the values when the flow is not fully turbulent, which is common when operating COBRs. It has been demonstrated that dimensionless power density is inversely proportional to the total flow Reynolds number in laminar flow and constant in turbulent flow, as is the case for flow in pipes and stirred tanks. For the geometry studied here (1/2) * = 330 !" 7 ⁄ in laminar flow and (1/2) * = 1.92 in turbulent flow.

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Section: Geometry and Operating Conditionssupporting

confidence: 55%

Predicting power consumption in continuous oscillatory baffled reactors

Avila

Fletcher

Poux

et al. 2020

Chemical Engineering Science

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“…9 As described in Figure 1, S controls the size and shape of eddies formed, while adequate distance between baffles (lb) ensures fully developed vortices and the minimization of mixing dead zones. 10,11 Baffle type also plays a major role and should be chosen appropriately for a given application. For example, a major concern in designing crystallization systems is minimizing shear stress, as it can lead to crystal breakage and broad size distributions.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the effect of scale-up on mixing efficiency in oscillatory flow baffled reactors (OFBR) using principal component based image analysis as a novel noninvasive residence time distribution measurement approach

Oliva

Pal

Barton

et al. 2018

Chemical Engineering Journal

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Oscillatory flow strategies through baffled tubular reactors provide an efficient approach in improving process kinetics through enhanced micromixing and heat transfer. Known to have high surface area to volume ratios, oscillatory flow baffled reactors (OFBR) generate turbulence by superimposing piston driven oscillatory flow onto the net flow generated by a pump. By tuning the oscillating parameters (amplitude and frequency), one can tailor the residence time distribution of the system for a variety of multiphase applications. Using a microscope camera, principal component image analysis, and pulse tracer injections, a novel noncontact approach has been developed to experimentally estimate dispersion coefficients in two geometrically different systems (DN6 and DN15, Alconbury Weston Ltd.). The paper also introduces for the first time a novel scaled-down version of the commercially available DN15 OFBR, the DN6 (about 10 times smaller scale), and provides a comprehensive experimental investigation of the effect of oscillation parameters on the residence time distributions (RTD) in both systems. The oscillation amplitude was found to have a significant positive correlation with the dispersion coefficient with 1 mm providing the least amount of dispersion in either system. Oscillation frequency had a less significant impact on the dispersion coefficient, but optimal operation was found to occur at 1.5 Hz for the DN6 and 1.0Hz for the DN15. Until now, OFBR literature has not distinguished between piston and pump driven flow. Pump driven flow was found to be ideal for both systems as it minimizes the measured dispersion coefficient. However, piston driven turbulence is essential for avoiding particle settling in two phase (solid-liquid) systems and should be considered in applications like crystallization.

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“…69,113,114 For continuous operation, the oscillation can be generated at one or both ends of the column using bellows, pistons or diaphragms. When considering continuous operation, the system should be operated such that the maximum oscillatory velocity is at least double the net velocity of the fluid flowing through the tube.…”

Section: Ofr Operating Principlesmentioning

confidence: 99%

Oscillatory Flow Reactors (OFRs) for Continuous Manufacturing and Crystallization

McGlone

Briggs

Clark³

et al. 2015

Org. Process Res. Dev.

180

198

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Continuous crystallization is an attractive approach for the delivery of consistent particles with specified critical quality attributes (CQAs) attracting increased interest for the manufacture of high value materials including fine chemicals and pharmaceuticals. Oscillatory flow reactors (OFRs) offer a suitable platform to deliver consistent operating conditions under plug-flow operation whilst maintaining a controlled steady state. This review provides a brief overview of OFR technology before outlining the operating principles and summarizing applications, emphasizing the use for controlled continuous crystallization. Whilst significant progress has been made to date, areas for further development are highlighted that will enhance the range of applications and ease of implementation of OFR technology. These depend on specific application but include scale down, materials of construction suitable for chemical compatibility and encrustation mitigation and the enhancement of robust operation via automation, process analytical technology (PAT) and real-time feedback control.

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Experimental Flow Visualisation in a Modified Pulsed Baffled Reactor

Cited by 21 publications

References 30 publications

Predicting power consumption in continuous oscillatory baffled reactors

Predicting power consumption in continuous oscillatory baffled reactors

Experimental investigation of the effect of scale-up on mixing efficiency in oscillatory flow baffled reactors (OFBR) using principal component based image analysis as a novel noninvasive residence time distribution measurement approach

Oscillatory Flow Reactors (OFRs) for Continuous Manufacturing and Crystallization

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