inclined rotating fixed bed reactors as a new reactor
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Inclined rotating fixed bed reactors as a new
reactor concept for process intensification
Hans-Ulrich Härting & Markus Schubert
Member of the Helmholtz Association Page 2
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Outline
Process Intensification: Periodic operation of trickle bed reactors
The inclined rotating fixed bed reactor
Alternative reactor concept
Experimental setup
Experimental studies
Tomographic imaging and flow regime maps
Gas-liquid mass transfer experiments for reactor evaluation
Conclusions & Outlook
Member of the Helmholtz Association Page 5
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Process Intensification: Trickle bed reactors
V. V. Ranade, R. V. Vhaudhari, P. R. Gunjal: Trickle Bed Reactors; Elsevier, Amsterdam, The Netherlands, 2011
Process Pressure
in Mpa
Temperature
in K
Ethanol oxidation on Pd/Al 2 343 – 373
Hydrodesulfurization on Mo-Ni 2 – 8 593 – 653
Fischer-Tropsch reaction on Co/TiO2 1 – 5 450 – 650
Gas-liquid-solid reactor for heterogeneous catalysis
Commonly gas and liquid (“trickling”) cocurrent downflow over
a fixed-bed of randomly packed catalyst particles
Disadvantages: liquid maldistribution, formation of hot spots,
poor radial heat transfer, low gas mass transfer rate
Initial liquid distribution crucial for reactor performance
Member of the Helmholtz Association Page 6
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Process Intensification: Periodic operation of TBR
Time
Liq
uid
flo
w r
ate
P. M. Haure et al.; AIChE Journal 35, 1989, pp. 1437
J. G. Boelhouwer et al.; Chem. Eng. Sci., 57, 2002, pp. 4876
Enhanced liquid distribution
Dampening of hot spots
Additional degrees of
freedom for reactor control
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Process Intensification: Explanation of periodic operation
M. Schubert et al.; Chem. Ing. Tech. 78, 2006, pp. 1023
G
G
G
G
Stationary operation:
„Steady“ liquid film and wetting
efficiency at catalyst surface
Periodic operation:
Forced perturbation of liquid film and
wetting efficiency at catalyst surface
M. E. Trivizadakis et al.; Chem. Eng. Sci. 61, 2006, pp. 7684
G
G
Time
Liq
uid
flo
w r
ate
Member of the Helmholtz Association Page 8
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Process Intensification: Deficiencies of peridodic operation
Dampening of pulse intensity with
reactor length
Interference with upstream and
downstream facilities in plant
increase in capex
Higher demands on process
measurement and control
increase in capex and opex
Higher demands on models for
design and simulation
J. G. Boelhouwer et al.; Chem. Eng. Sci., 57, 2002, pp. 3387
Member of the Helmholtz Association Page 9
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Outline
Process Intensification: Periodic operation of trickle bed reactors
The inclined rotating fixed bed reactor
Alternative reactor concept
Experimental setup
Experimental studies
Tomographic imaging and flow regime maps
Gas-liquid mass transfer experiments for reactor evaluation
Conclusions & Outlook
Member of the Helmholtz Association Page 10
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
The inclined rotating fixed bed reactor
α
Liquid
Gas
Idea:
Periodic operation with constant feed rates
Reactor inclination forces gas-liquid seggregation
Superimposed rotation induces periodic wetting of fixed bed
Fixed bed tightened inside of reactor by screens
Transformation of temporal-periodic operation into spatial-
periodic operation
Benefits:
Initial uniform liquid distribution irrelevant
Introduction of periodicity over whole length of reactor
Enhanced mass transfer for gas phase
Two further degrees of freedom for flow control
Quasi-stationary flow regimes more simple to describe
H.-U. Härting, M. Schubert; Chem. Ing Tech. 84, 2012, p. 1250
Saturation
1.0
0.0 Time
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
The inclined rotating fixed bed reactor: Design features
Inclinable inner
frame with rollers
and hollow shaft
actuator
γ-ray CT-system
(“CompaCT“) on
rotary stage
Tubular reactor
(DI = 102 mm
L = 1210 mm)
with rotary unions
and intermediate
flanges
L x H x D ≈ 2.5 m x 3 m x 1 m
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental setup: Tomographic imaging - CompaCT
A. Bieberle, H. Nehring, R. Berger, M. Arlit, H.-U. Härting, M. Schubert, U. Hampel; Rev. Sci. Instrum. 84, 2013, 033106
modular signal processing boards
base plate with integrated
cooling circuit centrifugal pump
Detector
collimator
isotopic source
collimator
hollow shaft
rotary actuator
gamma-ray detector arc
112 detectors, LYSO, A = 4x2 mm2
Isotopic source: 137Cs with A = 1.1 GBq, E = 662 keV
Integrated convective cooling circuit
Aperture ≈ Object-Ø : max. 150 mm
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
The inclined rotating fixed-bed reactor: In real life
Experimental setup CompaCT at work
Member of the Helmholtz Association Page 14
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Outline
Process Intensification: Periodic operation of trickle bed reactors
The inclined rotating fixed bed reactor
Alternative reactor concept
Experimental setup
Experimental studies
Tomographic imaging and flow regime maps
Gas-liquid mass transfer experiments for reactor evaluation
Conclusions & Outlook
Member of the Helmholtz Association Page 15
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: A short reminder on tomographic imaging
Acquisition of count rates for each detector d at
different angular position p
Two reference scans and scan of actual flow
experiment
Reconstruction of cross-sectional attenuation
coefficients by algebraic reconstruction technique
Calculation of βL,dyn = effective volume of flow
void volume
Projections
De
tecto
rs
βL,dyn
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Validation of CompaCT
A. Bieberle, H.-U. Härting, M. Schubert, U. Hampel; Proc. Eng., 2013, accepted
Mean systematic underestimation
of liquid saturation of about 2 %
No significant influence of rotational
speed on measured saturation
Aptitude of CompaCT for rotating reactor
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Identified flow regimes
Stratified flow
Stratified-sickle flow
Annular flow
Disperse flow
Comparison: Trickle flow Dynamic
liquid
saturation
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Flow regime map I
Deionate - air - 4 mm glass beads: ρ = 998 kg/m3 / η = 1 mPa*s / σ = 72.5 mN/m
H.-U. Härting, A. Bieberle, M. Schubert, U. Hampel; Proc. Eng., 2013, accepted
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Flow regime map II
Cumene - air - 4 mm glass beads: ρ = 862 kg/m3 / η = 0.8 mPa*s / σ = 28.2 mN/m
Rotational speed in rpm
Inclin
ation
an
gle
in
°
uL = 0.01 m/s & uG = 0.05 m/s
Stratified flow
Stratif ied-
sickle
flow
Annular flow
20 60 40 0 10 50 30
30
90
60
45
75
15
Dynamic
liquid
saturation
Member of the Helmholtz Association Page 22
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Flow regime maps – comparison
Cumene - air - 4 mm glass beads lowered density and surface tension
No disperse flow for cumene
Stratified-sickle flow less pronounced
Density in kg/m3 Viscosity in mPa*s Surface tension in mN/m
Deionized (DI) water 998 1 72.5
DI-water with
surfactant
996 1 55.5
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Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Gas-liquid mass transfer – method
M. Wiezorek; diploma thesis, TU Dresden, 2012
L G
Vin
Vout
z2
V2-(
Vin+
Vout)
L+G
Vin
Vout
z1
V1-(
Vin+
Vout)
L G
L+G
“Developed flow“:
Goto & Smith 1975, Luo & Ghiaasiaan 1997
(𝑘𝐿𝑎)𝑧1𝐴𝑧1 = 𝑘𝐿𝑎𝑑𝑉𝑉𝑖𝑛
+ 𝑘𝐿𝑎𝑑𝑉𝑉𝑜𝑢𝑡
+ 𝑘𝐿𝑎𝑑𝑉𝑉1−(𝑉𝑖𝑛+𝑉𝑜𝑢𝑡)
(𝑘𝐿𝑎)𝑧2𝐴𝑧2 = 𝑘𝐿𝑎𝑑𝑉𝑉𝑖𝑛
+ 𝑘𝐿𝑎𝑑𝑉𝑉𝑜𝑢𝑡
+ 𝑘𝐿𝑎𝑑𝑉𝑉2−(𝑉𝑖𝑛+𝑉𝑜𝑢𝑡)
Desorption of oxygen from deionate with pure nitrogen
Measurement with amperometric oxygen probes
Inlet and outlet effects considered, no dispersion
0 = −𝑣𝜕𝑐
𝜕𝑧− 𝑘𝐿𝑎 𝑐 𝑘𝐿𝑎 =
𝑉 𝐿𝐴𝐿
𝑙𝑛𝑐𝑖𝑛𝑐𝑜𝑢𝑡
O2 balance:
Member of the Helmholtz Association Page 24
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Gas-liquid mass transfer – results (I)
vG = 0.01 m/s and n = 10 rpm vG = 0.01 m/s and n = 60 rpm
TBR outperforms rotating reactor for lower rotational speed and vice versa
Mass transfer in rotating reactor decreases with increasing inclination for 10 rpm
Mass transfer in rotating reactor reaches maximum between 30° and 60° for 60 rpm
Member of the Helmholtz Association Page 25
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Gas-liquid mass transfer – results (II)
vG = 0.01 m/s and α = 15°
Better liquid distribution rather through higher liquid velocity than through rotation
Pronounced influence of liquid velocity
Negligible influence of rotational speed
vL = 0.01 m/s and n = 10 rpm
vL = 0.01 m/s and n = 40 rpm
vL = 0.03 m/s and n = 10 rpm
vL = 0.03 m/s and n = 40 rpm
Member of the Helmholtz Association Page 26
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Gas-liquid mass transfer – results (III)
vG = 0.01 m/s and α = 60°
Better liquid distribution through higher rotational velocity for lower liquid flow rate
Pronounced influence of liquid velocity as well as of rotational speed
vL = 0.01 m/s and n = 10 rpm
vL = 0.01 m/s and n = 40 rpm vL = 0.03 m/s and n = 40 rpm
vL = 0.03 m/s and n = 10 rpm
Member of the Helmholtz Association Page 27
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Experimental studies: Gas-liquid mass transfer – comparison
vG = 0.01 m/s and α = 60°
Gas-liquid mass transfer in new reactor concept depends strongly on liquid flow rate
Influence of rotational velocity increases with increasing inclination
vG = 0.01 m/s and α = 15°
Member of the Helmholtz Association Page 28
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Summary and outlook
Conclusions:
Proof of concept for controlling flow regimes by additional degrees of freedom
Successful application of a new, highly integrated gammy-ray tomograph
Identification of flow regimes for various systems and generation of flow regime maps
Future work:
Investigation of reactive behaviour about to start
Hydrogenation of AMS to cumene
Investigation of residence time distribution, radial and
axial dispersion via WLAN wire-mesh sensors
Implementation of 1-D reactor model with formulation
of adapted closure formulations for drag forces
Member of the Helmholtz Association Page 29
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
Acknowledgements
Funding by German Research Foundation (DFG), grant no. SCHU 2412/2-1
Department FWDF: gamma-ray CT, construction, installation
Student research assistants
Questions?
h.haerting@hzdr.de
Member of the Helmholtz Association Page 30
Hans-Ulrich Härting | Institute of Fluid Dynamics | www.hzdr.de
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