Internal-loop airlift reactor

Spatial Profiles of Gas Holdup in a Novel Internal-loop Airlift Reactor... 

Internal-loop airlift reactors (ALRs) are widely used for their self-induced circulation, improved mixing, and excellent heat transfer [1], This work reports on the design of an ALR with a novel gas-liquid separator and novel gas distributor. In this ALR, the gas was sparged into the annulus. The special designed gas-liquid separator, at the head of the reactor, can almost completely separate the gas and liquid even at high gas velocities. 

In this model, energy balances are set up for the reactor and the separator tube separately, and two equations are obtained. The gas holdup can then be obtained from combining these two equations. Details can be found in Zhang et al. [7]. The comparison between the measured and calculated cross-sectional mean gas holdups is shown in Fig. 5. It can be seen that there is a satisfactory agreement between the experimental and calculated gas holdup in the different operating conditions. Therefore, it is reasonable to conclude that the energy balance model used in this work can describe the circulation flow behavior in the novle internal-loop airlift reactor proposed in this work. 

A specially built conductivity probe was used to investigate the gas holdup in a novel internal-loop airlift reactor. The gas holdup generally increases with increasing solid holdup due to increased flow resistance. A model based on energy balance was developed that can be used to predict the average gas holdup in this novel interal-loop airlift reactor. 

Abstract This chapter embodies two sections. In the first section a survey of the state of the art of azo-dye conversion by means of bacteria is presented, with a focus on reactor design and operational issues. The relevance of thorough characterization of reaction kinetics and yields is discussed. The second section is focused on recent results regarding the conversion of an azo-dye by means of bacterial biofilm in an internal loop airlift reactor. Experimental results are analyzed in the light of a comprehensive reactor model. Key issues, research needs and priorities regarding bioprocess development for azo-dye conversion are discussed. 

Fig. 6 Acid orange 7 and phenol concentration in the internal loop airlift reactor operated with Pseudomonas sp. 0X1 biofilm on natural pumice. (A) Aerobic phase. Gas air. Liquid continuous feeding of phenol supplemented synthetic medium. (AN) Anaerobic phase. Gas nitrogen. Liquid batch conditions, dye supplemented medium...

Internal loop airlift reactor (ILALR) ILALR has an Internal flow separator creating channels for up- and downflow. + + ++ +++ ++ ++ Limited flow control... 

Blazej, M., Kisa, M., and Markos, J. (2004c), Scale influence on the hydrodynamics of an internal loop airlift reactor, Chemical Engineering and Processing, 43(12) 1519-1527. 

Freitas, C., and Teixeira, J.A. (2001), Oxygen mass transfer in a high solids loading three-phase internal-loop airlift reactor, Chemical Engineering Journal, 84(1) 57-61. 

Lo, C.-S., and Hwang, S.-J. (2003), Local hydrodynamic properties of gas phase in an internal-loop airlift reactor, Chemical Engineering Journal, 91(1) 3-22. 

Muthukumar, K., and Velan, M. (2006), Volumetric mass transfer coefficients in an internal loop airlift reactor with low-density particles, Journal of Chemical Technology Biotechnology, 81(4) 661-613. 

Wei, C., Xie, B., and Xiao, H. (2000), Hydrodynamics in an internal loop airlift reactor with a convergence-divergence draft tube, Chemical Engineering Technology, 23(1) 38-45. 

Wei, Y, Tiefeng, W, Malin, L., and Zhanwen, W. (2008), Bubble circulation regimes in a multi-stage internal-loop airlift reactor, Chemical Engineering Journal, 142(3) 301-308. 

Chao, Y., Ishida, T., Sugano, Y., Shoda, M., 2000. Bacterial cellulose production by Acetobacter xylinum in a 50-1 internal-loop airlift reactor. Biotechnology and Bioengineering 68, 345-352. 

Fig. 11. Airlift reactors, (a) internal loop airlift reactor, (b) external loop airlift reactor.

Fu CC, Fan LS, Wu WT Flow regime transitions in an internal-loop airlift reactor, Chem Eng Technol 30 1077—1082, 2007. 

Simcik M, Mota A, Ruzicka MC, et al CFD simulation and experimental measurement of gas holdup and liquid interstitial velocity in internal loop airlift reactor, Chem Eng Sci 66 3268-3279, 2011. 

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