Microreactors slug flow

Figure 4.35 Flow pattern map for the nitrogen/ acetonitrile flow in the dual-channel microreactor. Annular flow wavy annular flow (WA) wavy annular-dry flow, (WAD) slug flow bubbly flow annular-dry flow (AD). Transition lines for nitrogen-acetonitrile flows in a triangular channel (224 pm) (solid line). Transition lines for air-water flows in triangular...

Microreactors can be used for either gas-phase or liquid-phase reactions, whether catalyzed or uncatalyzed. Heterogeneous catalysts (or immobilized enzymes) can be coated onto the channel wall, although on occasion the metal wall itself can act as the catalyst. Gas-liquid contacting can be effected in the microchannels by either bubbly or slug flow of gas, an annular flow of liquid, or falling liquid films along the vertical channel walls. Contact between two immiscible liquids is also possible. The use of microreactor systems in the area of biotechnology shows much promise, not only for analytical purposes but also for small-scale production systems. 

Kashid, M. N., Gerlach, 1., Goetz, S., Franzke, J., Acker, J., Platte, F., et al. (2005). Internal circulation within the liquid slugs of a liquid-liquid slug-flow capillary microreactor. Industrial... 

Ghaini, A., Kashid, M., Agar, D. (2010). Effective interfacial area for mass transfer in the liquid-liquid slug flow capillary microreactors. Chemical Engineering and Processing Process Intensification, 49, 358—366. 

Kashid, M. N., Agar, D. W. (2007). Hydrodynamics of liquid-liquid slug flow capillary microreactor flow regimes, slug size and pressure drop. Chemical Engineering Journal, 131, 1-13. 

Kashid, M.N. (2007) Experimental and Modelling Studies on Liquid-Liquid Slug Flow Capillary Microreactors, University of Dortmund, Dortmund. 

Power input, a decisive parameter for benchmarking technical reactors, has been investigated using the experimental pressure drop and compared with conventional contactor as shown in Table 15.5. The comparison reveals that the liquid-liquid slug flow microreactor requires much less power than the alternatives to provide large interfacial area - as high as a = 5000 m m in a 0.5 mm capillary microreactor, which is way above the values in a mechanically agitated reactor (a 500 m m ). 

Liquid-liquid system in microreactors Burns and Ramshaw (2001) Slug flow Reacting system Kerosene-acetic acid-water + NaOH dn — 380 pm acetic acid, org — 0.65 M CNaOH,aq 0.1-0.4 M u = 0-35mms Order of magnitude of 0.5 s ... 

M. N. Kashid, Experimental and modelling studies on liquid-liquid slug flow capillary microreactors, PhD Thesis, Technical University of Dortmimd, 2007. 

Sulfonations are a further important type of electrophilic substitution reaction. However, only very few examples can be found in the literature describing the use of microstructured reactors for the strongly exothermic liquid-phase sulfonation of aromatics (sulfonation of toluene wdth gaseous SO3 was described by Jaehnisch et al. [34]). Burns and Ramshaw [25, 35] claimed that their concept of performing liquid/liquid nitration reactions in a slug-flow capillary-microreactor can be also... 

Figure 0.4 Observed flow regimes in the capillary microreactor (Y-junction ID = 1 mm, capillary ID = 1 mm), (a) Slug flow, (b) drop flow, and (c) deformed interface flow. (Adapted from Kashid, M.N. and Agar, D.W., Chem. Eng. J. 131, 1, 2007.)...

Kashid et al. [46] investigated mass transfer with and without chemical reaction in a liquid-liquid microreactor with slug flow (Figure 12.6). The authors modified Equations 12.21 and considered the computational domain to be two dimensional ... 

Kashid, M.N., Agara, D.W., and Turek, S. (2007) CFD modelling of mass transfer with and without chemical reaction in the liquid-liquid slug flow microreactor. Chem. Eng. Sci., 62, 5102-5109. 

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