Poster De Conférence Année : 2023

Development of an innovative tool to characterize the fluid maldistribution in structured reactors

Résumé

Intensified structured multiphase reactors offer millimetric channels to the reactive fluids, leading to better performance for heat and/or mass transfer and for reaction yield and selectivity. However, these benefits require an even distribution of fluids and phases among the reactor channels, otherwise artificial dispersion appears for the overall flow in the reactor and hinders its productivity. Thus, fluid maldistribution in these multi-channel reactors is a crucial issue to study and to sort out (Roy et al., 2019). However, efficient experimental methods to investigate maldistribution, as described in literature, are few and complex, as tomography or Magnetic Resonance Imaging techniques (Devatine et al., 2017). In this work, an innovative tool is specifically designed: two perforated plates, holding gold ring electrodes, are connected to the reactor channels. When gas and liquid flow along the channels and through sensor holes, the signals issued from the electrode terminals are simultaneous recorded at high frequency (up to 20 kHz). Each signal is linked to the flow regime and major hydrodynamic characteristics of the corresponding channel. In this study, we focus on the Taylor flow regime, which is well known for its high mass transfer efficiency and moderate pressure drop (Kreutzer et al., 2005). The sensor response is modelled by taking into account the geometrical features of Taylor flow, the average resistance between annular electrodes when lubricated bubbles pass through, and the electronic behaviour of the sensor. Thus, a methodology is developed to determine the flow parameters from signal processing. Experiments are performed with air and water at ambient conditions in a monolith-type device offering twelve transparent parallel channels (inner diameter: 2 mm) made in epoxy resin. Maldistribution can be observed in these channels. Overall gas and liquid flowrates are varied and flows are recorded with a high speed camera: images are processed to assess the values issued from sensor signal processing. Results from both techniques are compared in terms of bubble frequency, bubble velocity, phase retention. Average bubble frequency and bubble velocity in the channels are quite well captured through the sensor signal processing. For gas retention, results are satisfying (Figure 1.b), though their relevance depends on bubble shape and size, and on slug length. Thus, for a given experiments (given overall gas and liquid flow rates), liquid and gas flowrates feeding each of the 12 channels can be calculated, and maldistribution can be qualified. The various performed experiments allow then to investigate the impact of overall gas and liquid flowrates on maldistribution for this particular device.

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Dates et versions

hal-04752639 , version 1 (24-10-2024)

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Identifiants

  • HAL Id : hal-04752639 , version 1

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Murilo Ricardo Do Nascimento Arrais, Hélène Chaumat, Audrey Devatine, Carine Julcour, Anne-Marie Billet. Development of an innovative tool to characterize the fluid maldistribution in structured reactors. 14th European Congress of Chemical Engineering and 7th European Congress of Applied Biotechnology, Sep 2023, Berlin, Germany. 2023. ⟨hal-04752639⟩
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