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Interpretation of gas residence time distributions in large airlift tower loop reactors

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Abstract

Gas-residence time distribution (RTD) response curves measured in a 23 m high pilot plant airlift tower loop reactor, which consisted of a riser, a special downcomer construction and at the top of the riser a large head. The measurements were evaluated by means of a deterministic dispersion model, which yielded the following particular parameters for the riser, downcomer and the head: Gas-Bo numbers, gas-mean residence times, gas holdups, liquid velocities, gas and liquid circulation times as well as a fraction of the large and small bubbles in a model medium (water) and during cultivation of baker's yeast.

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Abbreviations

A :

cross section

Bo :

Bodenstein number

Bo d :

(= l d w G,d /D d )

Bo h :

(= l h w G,h /D h )

Bo r :

(= l r w G,r /D r )

D :

longitudinal dispersion coefficient

E :

gas holdup

E(t) :

RTD-density function

L, l :

length parameter

q :

fraction of the gas throughput which is not recirculated (approximately equal to fraction of the large bubbles)

r :

fraction of the throughput which is recirculated (approximately equal to the fraction of the small bubbles)

t c :

circulation time

t cL :

liquid circulation time

t * c,L :

liquid circulation time calculated from the measured w Ld in the downcomer

V h :

hydrodynamical calculated gas-liquid volume

V h d :

(=V d+0.75/2 V k )

V h k :

=(0.25V k )

V h r :

= (V r+0.75/2 V k )

V L :

liquid volume

V G :

dispersed gas volume

V * G :

gas throughput at the gas distributor (given in m3/h) under standard conditions, 1 bar and 25°C)

V * G,d :

gas throughput in downcomer (=V * G α)

V * G,h :

gas throughput in head (=V * G )

V * G,r :

gas throughput in riser (V * G (1+α)

w g :

gas velocity

w G,rel :

relative gas velocity with respect to the liquid velocity w L

w G,d :

gas velocity in the downcomer (=w G,rel −w Ld )

w G,h :

gas velocity in the head (=w G,rel ) (since wLh = o)

w G,r :

gas velocity in the riser (=w G,rel +w Lr )

w L :

liquid velocity

w L,d :

liquid velocity in the downcomer measured with mass flow meter

w sg ·w SL :

superficial gas and liquid velocities

μ :

first moment of the response curve

τ :

mean residence time

d :

downcomer

G :

gas phase

h :

head

L :

liquid phase

r :

riser

h :

hydrodynamic (upper position)

References

  1. Deckwer, W. D.: Bubble Column Reactors. Chichester: Wiley 1992

    Google Scholar 

  2. Chisti, M. Y.: Airlift bioreactors, London: Elsevier 1989

    Google Scholar 

  3. Fröhlich, S.; Lotz, M.; Korte, T.; Lübbert, A.; Schügerl, K.; Seekamp, M.: Characterisation of a pilot plant airlift tower loop bioreactor. I: Evaluation of the phase properties with model media. Biotechnol. Bioeng. 38 (1991) 43–45

    Google Scholar 

  4. Fröhlich, S.; Lotz, M.; Körte, T.; Lübbert, A.; Schügerl, K.; Seekamp, M.: Characterisation of a pilot plant airlift tower loop bioreactor. II: Evaluation of global mixing properties of the gas phase during yeast cultivation. Biotechnol. Bioeng. 37 (1991) 910–917

    Google Scholar 

  5. Wan, L: Detaillierte Untersuchungen des Mischverhaltens realer Mehrphasenreaktoren. Dissertation, University Hannover, 1990

  6. Lübbert, A.; Larson, B.; Wan, L.; Bröring, S.: Local mixing behaviour of airlift multiphase chemical reactors. I. Chem. E. Symposium Series No. 121, pp. 203–213. Washington, DC: Hemisphere 1990

    Google Scholar 

  7. Rüffer, H. M.: Untersuchugen zur Charakterisierung der Fluidynamik in Bioreaktoren. Dissertation, University Hannover, 1990.

  8. Bevington, P. R.: Data reduction and error analysis for the physicalscience, New York: McGraw-Hill 1969

    Google Scholar 

  9. Abel, C.; Hübner, U.; Schügerl, K.: Transient behaviour of Baker's yeast during enforced periodical variation of dissolved oxygen concentration. J. Biotechnol. 32 (1994) 45–57

    Google Scholar 

  10. Rüffer, H. M.; Pethö, A.; Schügerl, K.; Lübbert, A.; Ross, A.; Decker, W. D.: Interpretation of the gas residence time distributions in large stirred tank reactors Bioprocess Engng. (1994) (in print)

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Author notes

  1. H. M. Rüffer

    Present address: Hoechst Co, Höchst

Authors and Affiliations

  1. Institut für Technische Chemie, Universität Hannover, Callinstr. 3, D-30167, Hannover, Germany

    H. M. Rüffer, Liwei Wan, A. Lübbert & K. Schügerl

Authors
  1. H. M. Rüffer
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  2. Liwei Wan
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  3. A. Lübbert
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  4. K. Schügerl
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Additional information

Dedicated to the 65th birthday of Proffessor Fritz Wagner.

The authors gratefully acknowledge the financial support by the Krupp Industrietechnik, Grevenbroich and the support of Pleser Co, Darmstadt. H. M. Rüffer thanks the Verband der Chemischen Industrie for a Fond der Chemie scholarship, and W. Liwei thanks the government of Lower Saxony for a graduate scholarship.

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Rüffer, H.M., Wan, L., Lübbert, A. et al. Interpretation of gas residence time distributions in large airlift tower loop reactors. Bioprocess Engineering 11, 153–159 (1994). https://doi.org/10.1007/BF00518737

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