Design and CFD analysis of mass transfer and shear stresses distributions in airlift reactor

Transcription

1 University of Sherbrooke From the SelectedWorks of Rachid BANNARI June 3, 2009 Design and CFD analysis of mass transfer and shear stresses distributions in airlift reactor Rachid Bannari Brahim Selma Abdelfettah bannari Pierre Proulx Available at:

2 Design and CFD analysis of mass transfer and shear stresses distributions in airlift reactor 4 th OpenFOAM workshop Montréal, 1-4 june 2009 R. Bannari, B. Selma, A Bannari and P. Proulx Department of Chemical Engineering & Biotechnology Université de Sherbrooke (QC)

3 Outlines Oppus Group projects. Oppus Group projects. Realization on O.FOAM Objectives Numerical approach Computational and experimental results Conclusion

4 Projects of Oppus group Mathematical modelling of: 1- Multiphase reacting flow 2- Strongly coupled fluid 3- Population balance 4- Production of nanoparticles by plasma reactors.

5 Realization on Open FOAM Multiphase flow: Adaptation of turbulence Model 1 to resolve numerical instability Utilities: MRF on 1.3 version FluentDataToFoam: converter the Fluent Data to Foam (1.4.1version) PBES: Population balance equation: CM: Class Method 1 DQMOM: Method of Moments 2 Kinetic for the growth of filamentous microorganisms (cellulase production ) Solvers: PlasmaFoam: Solver for Argon inductively coupled plasma. [1] Bannari et al., 2008 [2] Selma and Proulx, 2007

6 PlasmaFoam Hypothesis:

7 PlasmaFoam Equations:

8 PlasmaFoam Equations:

9 PlasmaFoam

10 PlasmaFoam

11 PlasmaFoam

12 PlasmaFoam

13 PlasmaFoam

14 PlasmaFoam

15 PlasmaFoam

16 PlasmaFoam

17 Background Developing a model for the growth of filamentous microorganisms, application to aerated bioreactors (airlift, stirred tanks).

18 Background Benefit of Ethanol: environmental (Use of 10% ethanol-blended fuels ): 30% Reduction in Carbon Monoxide (CO) Emissions. 1 0% Reduction in Net Carbon Dioxide (CO2) Emissions. economy Energy Security and independence. Economic development opportunity to the rural areas where the ethanol is made.

19 Background Enzyme production The Production of Ethanol from Cellulosic Biomass

20 Objectives... Optimise the Cellulase production? get more biomass for the same cost!! The good candidate: T.ressei fungus Influencing parameters: growth media cultivation conditions (PH, temperature, DO, Agitation,...).

21 Objectives... Shear stress Mass transfer Mixing Complex interactions between morphology, productivity and process conditions in submerged fermentations of filamentous micro-organisms

22 Objectives... Study of shear stress Study of mass transfer Improve the design

23 Experimental Results... With the first proposed geometry: morphology does not adequate to produce cellulase (Small hyphae length and small number of tips). with a high viscosity the desired behavior of airlift internal loop changed (air disperse not only within the airlift central column but also in the external cylinder).3 height shear stress? 4,5 mass transfer. Design 3- Marten et al.,1996 ; 4- Cui et al., 1997; 5-Berzins et al., 2001

24 Proposed Design... Move-up the inlet. Use of microbubbles to ensure height mass transfer (Fisher brand gas diffusing stones) Stokes equation: Fisher brand gas diffusing stones

25 Proposed inlet...

26 Proposed Design without Agitator...

27 Proposed Design with Agitator... Numerical results view planes

28 Numerical approach... twophaseeulerfoam (modified k-epsilon + PBES ).1 twophaseeulerfoammrf (modified k-epsilon + PBES + MRF ). PBES: bubble size distribution is divided into 11 sections using a geometrical distribution method: mean diameter = 1.5 mm r = 1.51 Volume fraction for bubble size i [1] Bannari et al., 2008

29 Numerical approach Server Name : Mammouth-parallel (MP) Type : Parallel Cluster (MPI) Nodes : 576 (Dell 1425SC) Processors : 1152 Intel Xeon, 3.6 GHz Memory : 4 GB / CPU Interconnect : Infiniband 4X Peak performance (measured) : 6,888 Gflops Mp has been Canada's most powerful super computer from May 2005 to May 2008

30 Numerical and experimental results

31 Numerical results... Sauter mean diameter (d32)

32 Numerical results... Mass transfer (KLa) Shear stress

33 Numerical results... Mass transfer (KLa) Shear stress

34 Numerical results...

35 Numerical results...

36 Experimental results with new geometries Length of the hyphae decrease because of the higher shear Confirmed also by Metz 5:

37 Conclusion Increase of mass transfer (about 30 %). The global and local increase of mass transfer is the same. Decrease of shear stress in different zones. Morphology adequate to produce cellulase.

38 Thanks! The authors would like to thank the people involved in the development of the OpenFOAM package at the London Imperial college (H. Weller and H, Jasak in particular) and in general the OpenFOAM community for their generous contributions to the ideas that lead to the continuous development of this package. Special thanks for my supervisor Pr. Pierre Proulx for his support and for the sophisticated materials invested in our Laboratory.

39 Bibliographie 1- Bannari, R., Kerdouss, F., Selma, B., Bannari, A. and Proulx, P. (2008). Three-Dimensional Mathematical Modeling of Dispersed Two-Phase Flow Using Class Method of Population Balance in Bubble Columns. Computers and Chemical Engineering, 32, B. Selma and P.Proulx (2007). Application of population balance Equation on the molten aluminum purification. 3rd international Conference on Population Balance Modeling, September 2007, Quebec, Canada 3- Marten, M. R., Velkovska, S., KHAN, S. A, OLLIS, D. F., (1996). Rheological, mass transfer, and mixing characterization of cellulase-producing Trichoderma reesei suspensions. Biotechnology progress, 1996, 12, Y. Q. Cui, R. G. J. M. van der Lans and K. Ch.A. M. Luyben Effects of dissolved oxygen tension and mechanical forces on fungal morphology in submerged fermentation. Biotechnol. Bioeng Berzins, A., Toma, M., Rikmanis, M. Viesturs, U Influence of Micromixing on Microorganisms and products. Acta Biotechnol, 21, (2),