Journal of Advanced Chemical Engineering

Mass transfer efficiency comparison of air-lift reactor, stirred tank and stirred air-lift reactor

2^nd International Conference on Advances in Chemical Engineering and Technology

November 16-17, 2017 | Paris, France

Tuomas Koiranen

Lappeenranta University of Technology, Finland

Posters & Accepted Abstracts: J Adv Chem Eng

Abstract:

Statement of the Problem: Gas-liquid contacting reactors are employed in various biological and chemical applications because of their specific characteristics. Applications are for example biological wastewater treatment (denitrifying, phenolic treatment and waste gas treatment), oxidation and chlorination processes, microbial fermentations and production of biomass and metabolites. In many biological and chemical reactions gas-liquid mass transfer for gas dissolution is the bottle-neck of progress because of fast reaction kinetics. Mass transfer depends on physicochemical properties of chemical components and flow characteristics in the reactor. Gas hold-up, gas-liquid specific area, liquid and gas flow velocities are typically specified by the reactor geometry. Methodology & Theoretical Orientation: Overall gas-liquid mass transfer is measured using dissolved gas concentration in liquid phase, and local gas holdups are measured using tomographic measurements, such as electric resistance (ERT) or impedance (EIT) tomography. Particle image velocimetry (PIV) is used for the determination of flow velocities in the reactors. These measurements are used for verification of multi-phase flow model in reactors using Computational fluid dynamics (CFD). Findings: CFD is used for the determination of local mass transfer conditions. It serves for the evaluation of maximum and minimum mass transfer in air-lift, stirred tank and stirred air-lift reactors. The research has been done in FERMATRA (�??Tackling mass transfer challenges in fermentations�?�) project funded by Finnish Funding Agency for Innovation, TEKES. Conclusion & Significance: The mass transfer efficiency depends on mixing energy. Air-lift reactor, stirred tank reactor and stirred air-lift reactors have specific mass transfer (kLa) ranges due to the operational conditions. The comparison is made according to characteristic bubble size, gas superficial velocity and according to specific mixing power introduced by impellers.