Investigation of mixing in a rotor shape modified Taylor-vortex reactor by the means of a chemical test reaction

• Published in: Chemical engineering science Vol. 64; no. 10; pp. 2384 - 2391
• Main Authors: Richter, Oliver, Menges, Markus, Kraushaar-Czarnetzki, Bettina
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2009; Elsevier
• Subjects: Alkaline saponification; Applied sciences; Chemical engineering; Ethylacetate; Exact sciences and technology; Hydrodynamics of contact apparatus; Macromixing; Micromixing; Reactors; Taylor–Couette reactor; Micromixing; Ethylacetate; Macromixing; Alkaline saponification; Taylor–Couette reactor; Mixing; Taylor vortex; Taylor-Couette reactor; Segregation; Hydrodynamics; Continuous stirred tank reactor; Reaction rate; Rotor; Saponification; Relaxation time; Plug flow; Continuous process; Surveillance; Morphology; Kinetics
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2009.02.015

The macro- and micromixing properties of a continuous flow Taylor-vortex reactor can be optimised by changing the conventional cylindrical rotor geometry into a novel ribbed one. A chemical test reaction, the micromixing-sensitive alkaline saponification of ethylacetate with separately fed reactants, was used to probe the mixing performance down to the molecular level. Experiments were performed in a continuous flow Taylor-vortex reactor equipped either with a conventional cylindrical rotor or with a novel ribbed rotor in a wide hydrodynamic range of 150 < Ta < 8000 and 0.8 < Re < 2.0 . Through increase in the reaction temperature and the feed concentrations, the relaxation times of this reaction were reduced from 680 to 19 s and compared to micromixing times by monitoring the reactor conversion. The results show that a TVR with conventional rotor achieves intense micromixing at high rotor speed, but behaves like a CSTR. In contrast, a device with ribbed rotor shows macromixing features close to those of a plug flow reactor (PFR) in a wide range of rotor speeds; however, segregation of the two feeds could only be dissipated at slow reaction rates, i.e. relaxation times larger than 64 s.