Coiled flow inverter as a novel alternative for the intensification of a liquid-liquid reaction

• Published in: Chemical engineering science Vol. 169; pp. 179 - 185
• Main Authors: López-Guajardo, Enrique, Ortiz-Nadal, Enrique, Montesinos-Castellanos, Alejandro, Nigam, Krishna D.P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 21.09.2017
• Subjects: Coiled flow inverter; Helical coiled tube; Liquid-liquid reaction; Process intensification; Transesterification; Helical coiled tube; Coiled flow inverter; Process intensification; Transesterification; Liquid-liquid reaction
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2017.01.016

•The intensification of a liquid-liquid reaction is possible in CFIs.•Performances between CFIs, Batch, Helical and Straight Tube reactors are compared.•96% oil conversion is achieved within 4min residence time in the CFIs.•No further improvement in oil conversion is observed after seven 90° bends.•Experiments with a reduction in methanol excess are explored in CFIs. This paper explores a novel alternative to conventional biodiesel production by taking advantage of the mixing, mass and heat transfer enhancement inherent in coiled flow inverters (CFIs) using the transesterification of fatty acids as a model reaction. The results show that the reaction can be carried out twelve times faster in a CFI than in a batch reactor, with a conventional oil to methanol molar ratio of 1:6 (100% excess methanol). The mixing enhancement in CFIs increases the mass transfer between the reacting phases, achieving conversions of up to 93% for 2min residence time at 10ml/min with seven 90° bends. The performance of CFIs was compared to that of simple helical and straight tube reactors under the same operational conditions. The conversion observed in the CFIs was up to 18% higher than the conversion obtained in the helical and straight tube reactors. However, all the reactors achieved similar oil conversions when a longer residence time (4min) was allowed under the same flow rate conditions. Additional experiments with CFIs were carried out in order to explore lower oil:methanol molar ratios. The experimental results suggest that CFIs are capable of achieving conversions of up to 90% at 50% methanol molar excess (1:4.5 oil:methanol ratio) with a 4min residence time, which contrasts with the 60min required in batch reactors to achieve the same conversion. The results confirm that CFIs successfully intensify liquid-liquid reactions such as the transesterification of fatty acids when compared to a batch reactor.