Abstract
Residence time distribution (RTD) experiments were carried out using the catalytic packing MULTIPAK® in a 250 mm inner diameter column. The axial dispersion coefficients and dynamic liquid hold-up were derived from the RTD curves. Both hold-up and axial Péclet number were correlated in terms of gas and liquid Reynolds numbers. Free-draining experiments were performed to determine the dynamic and static liquid hold-ups.
The measured axial dispersion coefficients were higher than those presented in other studies. The dynamic hold-up derived from RTD agreed with total hold-up from free-draining experiments. The static hold-up was found very high, even higher than the dynamic one, due to the liquid accumulated inside the catalyst bed. Possibly, the liquid considered “static” from the viewpoint of the free-draining experiments becomes “dynamic” during the normal column operation.
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Abbreviations
- a:
-
specific surface area. m2 m−3
- c:
-
tracer concentration. kg m−3
- D ax :
-
axial dispersion coefficient. m2 s−1
- d c :
-
column diameter. m
- E(t):
-
residence time distribution function, eqn (4)
- h d :
-
liquid dynamic hold-up (RTD experiments). m3 m−3
- h fd :
-
liquid dynamic hold-up (free-draining experiments). m3 m−3
- h st :
-
liquid static hold-up. m3m−3
- h t :
-
liquid total hold-up (free-draining experiments) (= h fd + h st). m3 m−3
- L:
-
length (height) of column. m
- M:
-
mass of tracer injected. kg
- m n :
-
n-th moment of RTD curve, eqn (5). kg sn+1 m−3
- Pe L :
-
axial Péclet number, eqn (3)
- Re L :
-
liquid Reynolds number (based on interstitial velocity)kin (= 4u LρLε /(aη L))
- Re 0L :
-
liquid Reynolds number (based on superficial velocity) (= 4u 0LρLε /(aη L))
- Re G :
-
gas-phase Reynolds number (= 4u 0GρGε /(aη G))
- t, t m :
-
time, mean residence time. s
- u L :
-
liquid interstitial velocity. m s−1
- u 0L, u 0G :
-
liquid, gas superficial velocity. m s−1
- V*:
-
volumetric liquid flow. m3 s−1
- Z:
-
dimensionless longitudinal coordinate, eqn (2b)
- z:
-
longitudinal coordinate. m
- ε:
-
void fraction. m3 m−3
- η L, η G :
-
liquid, gas dynamic viscosity. Pa s
- μ 2 :
-
2nd moment, eqn (8). s2
- ϑ:
-
dimensionless time, eqn (2b)
- ρ L, ρ G :
-
liquid, gas density. kg m−3
- σ:
-
variance, eqn (8). s
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Górak, A., Jaroszyński, M. & Kołodziej, A. Residence time distribution study for the catalytic packing MULTIPAK®. Chem. Pap. 60, 404–409 (2006). https://doi.org/10.2478/s11696-006-0074-0
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DOI: https://doi.org/10.2478/s11696-006-0074-0