Skip to main content
SpringerLink
Log in

Residence time distribution of liquid phase in an external-loop airlift bioreactor

  • Originals
  • Published:
Bioprocess Engineering Aims and scope Submit manuscript

Abstract

The residence time distribution analysis was used to investigated the flow behaviour in an external-loop airlift bioreactor regarded as a single unit and discriminating its different sections. The experimental results were fitted according to plug flow with superimposed axial dispersion and tank-in-series models, which have proved that it is reasonable to assume plug flow with axial dispersion in the overall reactor, in riser and downcomer sections, as well, while the gas separator should be considered as a perfectly mixed zone. Also, the whole reactor could be replaced with 105-30 zones with perfect mixing in series, while its separate zones, that is the riser with 104-27, the downcomer with 115-35 and the gas separator with 25-5 perfectly mixed zones in series, respectively, depending on gas superficial velocity, AD/AR ratio and the liquid feed rate.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Abbreviations

A D :

cross sectional area of downcomer (m2)

A R :

cross sectional area of riser (m2)

A 1 A 2 :

length of connecting pipes (m)

Bo :

Bodenstein number (Bo=vL·L/D ax (-)

C :

concentration (kg m–3)

C :

residence time distribution function

C 0 :

coefficientEquation (12)

C r :

dimensionless concentration

D D :

diameter of downcomer (m)

D R :

diameter of riser column (m)

D ax :

axial dispersion coefficient (m2s–1)

H d :

height of gas-liquid dispersion (m)

H L :

height of clear liquid (m)

i :

number of complete circulations

L :

length of path (m)

m :

order of moments

N eq :

number of perfectly mixed zones in series

n c :

circulating number

Q c :

recirculating liquid flow rate (m3 s–1)

q F :

liquid feed flow rate (m3s–1)

Q G :

gas flow rate (m3s–1)

Q T :

total liquid flow rate (m3s–1)

r :

recycle factor

s :

exponent inEquation (12) regarded as logarithmic decrement of the oscillating part of RTD curve

t :

time (s)

t C :

circulation time (s)

t s :

mean residence time (s)

t 99 :

time necessary to remove 99% of the tracer concentration (s)

V A :

volume of connecting pipes (m3)

V D :

volume of downcomer (m3)

V L :

liquid volume in reactor (m3)

V R :

volume of riser (m3)

V LD :

linear liquid velocity in downcomer (m s–1)

V LR :

linear liquid velocity in riser (m s–1)

V SLD :

superficial liquid velocity in downcomer (m s–1)

V SLR :

superficial liquid velocity in riser (m s–1)

x :

independent variable inEquation (1)

¯x :

mean value of x

z :

axial coordinate

ɛ GR :

gas holdup in riser

μ m(x) :

central moment of m order

σ 2 :

variance

τ :

dimensionless time

References

  1. Blenke, H.: Loop Reactors. In Advances in Biochemical Engineering, Vol. 13, eds. T.K. Ghose, A. Fiechter and N. Blackebrough. Springer, Berlin-Heidelberg-New York, 1979, pp. 120–214

    Google Scholar 

  2. Chisti, M.Y.: Airlift Bioreactors, Elsevier Applied Science, London-New York, 1989

    Google Scholar 

  3. Merchuk, J.C.: Tower Reactor Models. In Biotechnology, eds. H-J. Rehn and G. Reed, Vol. 4, ed. K. Schügerl, VCH, Weinheim, 1991 pp. 349–382

    Google Scholar 

  4. Moser, A.: Continuous Cultivation. In Biotechnology, eds. H-J. Rehm and G. Reed, Vol. 2, ed. H. Brauer, VCH, Weinheim, 1985, pp. 285–309

    Google Scholar 

  5. Blenke, H.: Biochemical Loop Reactors. In Biotechnology, eds. H-J. Rehm and G. Reed, Vol. 2, Ed. H. Brauer, VCH, Weinheim, 1985, pp. 465–517

    Google Scholar 

  6. Lavric, V.: Biological Reactors with Bubble Bed. Ph.D. Thesis, University Politechnica Bucharest, Bucharest, 1994

    Google Scholar 

  7. Fields, P.R.;Slater, N.K.H.: Tracer Dispersion in a Laboratory Airlift Reactor. Chem. Eng.Sci. 38 (1983) 647–653

    Google Scholar 

  8. Levenspiel, O.: Chemical Reaction Engineering, John Wiley and Sons, New York, 1972

    Google Scholar 

  9. Swaine, D.E.;Daugulis, A.J.: Review of Liquid Mixing in Packed Bed Biological Reactors. Biotechnology Progress 4 (1988) 134–148

    Google Scholar 

  10. Warnecke, H.J.;Prüss, J.;Langemann, H.: On a Mathematical Model for Loop Reactors-I. Residence Time Distribution Moments and Eigenvalues. Chem. Eng. Sci. 40 (1985) 2321–2326

    Google Scholar 

  11. Warnecke, H.J.;Prüss, J.;Leber, L;Langemann, H.: On a Mathematical Model for Loop Reactors-II. Estimation of Parameters. Chem. Eng. Sci. 450 (1985) 2327–2331

    Google Scholar 

  12. Warnecke, H.J.: Macromixing Characteristics of Gas-Liquid Jet Loop Reactors. Acta Biotechnol 9 (1989) 111–121

    Google Scholar 

  13. Popovic, M.;Robinson, C.W.: External-Circulation-Loop Airlift Bioreactors: Study of the Liquid Circulating Velocity in Highly Viscous Non-Newtonian Liquids. Biotechnol. Bioeng. 32 (1988) 301–312

    Google Scholar 

  14. Chakravarty, M.;Begum, S.;Singh, H.H.;Baruah, J.N.;Yengar, M.: Gas Hold-Up Distribution in a Gas-Lift Column. Biotechnol. Bioeng. Symp. 4 (1973) 363–378

    Google Scholar 

  15. Lans, van der, R.G.J.M.: Hydrodynamics of a Bubble Column Loop Reactor, Ph.D. thesis, Delft University of Technology, Delft, 1985

    Google Scholar 

  16. Verlaan, P.: Modelling and Characterization of an Airlift-Loop Bioreactor. Ph.D. Thesis, University of Wageningen, Wageningen, 1987

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Chemical Pharmaceutical Research Institute, Research Center for Antibiotics, 6647 Valea Lupului no. 1, IASI, Romania

    M. Gavrilescu

  2. Faculty of Industrial Chemistry, Department of Transfer Phenomena and Chemical Engineering, Technical University of IASI, 6600 IASI, Romania

    R. Z. Tudose

Authors
  1. M. Gavrilescu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. R. Z. Tudose
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Gavrilescu, M., Tudose, R.Z. Residence time distribution of liquid phase in an external-loop airlift bioreactor. Bioprocess Engineering 14, 183–193 (1996). https://doi.org/10.1007/BF01464733

Download citation

  • Received:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF01464733

Keywords

Search

Navigation