1. David Follansbee, John Paccione, Lealon Martin
Environmental Division
Fundamentals of Environmental
Systems Engineering
Optimal design and operation of a Draft Tube Spouted Bed Reactor for a photocatalytic process
David Follansbee, John Paccione, Lealon Martin
Tuesday, November 6, 2007

2. Outline Motivation for process Process Model
Parameters and Problem statement
Results
Conclusion and Future Work

3. Traditional photocatalytic Reactors
Photocatalytic slurry reactors
Batch configuration
Photocatalyst particle separation
Photocatalyst loading limitations
Photocatalytic fixed bed reactors
Cross sectional area limitations
Longer reactor length for increase throughput
High pressure drops
Mass transfer and kinetics are coupled
Photocatalyst coating of reactor walls
Cross sectional and mass transfer limitations

4. Motivation for DTSMB Decoupling of mass transfer from kineticsUV
Jet flow
Decoupling of mass transfer from kinetics
Continual degradation of contaminant and regeneration of photocatalyst
Counter-current design
Photocatalyst immobilized on large, dense particles
Draft tube
Clean water outlet
Dirty Water inlets

5. Process block diagram Design Parameters Photo Reactor WUV TargetDA εA Dt
Design
Parameters Gp
Gfd HA
Key design
variables M εD
WUV
WPump .
Performance
variables xo xi
Photo Reactor
Gfa yi yo
Target
Parameters
Draft tube
Packed bed
reactor

6. Annular bed Model Gp xi GA Gp yo xi xo yo M HA H HA Gp GA yi GA xo yi
Assumptions:
Counter current contact
Constant fluid properties
Costant particle size and density DA M HA
Mass load :
Mass balance:
Log mean concentration difference:
Height:
Langmuir adsorption: Gp GA xi yi GA yo Gp xo xi HA yo H Gp
Annular bed model
Langmuir
Variables consistant
Left-right GA xo yi
A. Y. Khan. Titanium dioxide coated activated carbon: Masters thesis, University of Florida, 2003.
V. Manousiouthakis and L. L. Martin. Computers & Chemical Engineering, 28(8):1237–1247, July 2004.

7. Draft tube model Assumptions Only non-accelerating portion of bed Gp
Slip velocity:
Mass flowrate of fluid:
Mass flow rate of particles:
Fluid-particle interphase drag coefficient:
Pressure Drop
GfD Dt Ht εD
Line up text and equations Gp
GfD
Z. B. Grbavcic, R. V. Garic, D. V. Vukovic, D. E. Hadzismajlovic, H. Littman, M. H. Morgan, and S. D. Jovanovic. Powder Technology, 72(2):183–191, Oct

8. UV model (Intensity, Power, and Kinetics)
Modeled as a PFR
Pseudo first order reaction
No mass transfer limitations Gp xo I
Intensity (Lambert-Beer Law):
Adsorption coefficient:
Power required:
DUV
Mass flow rate:
Rate equation:
HUV Io
WUV . Gp xi

9. Operation limitations and specifications
Mass flowrate can not exceed an upper limit where particles will not settle in annular bed
Gp<(1-mf)Aapva(max)
Voidage in the draft tube has to be above a critical collapsing voidage and below 1
vc< D<1
The fluid velocity has to be great enough to ensure transport of particles
u1.5vt
Operating specs
New slide
{Problem statement}
Objective function
Make clear
Utlity, captial, annual

10. Test System Reactive Red degradation 2 mm catalyst particles
TiO2/AC photocatalyst composites
SiO2 substrate

11. Design Parameters  p 2507 kg/m3 f 1000 f 1.119*10-3 Ns/m2 Dt 1 inDA 6
DUV 2 Dp mm At AA
AUV Ht
2.5 m
HUV
1.22
vterminal
0.257
m/s g
9.81
m/s2

12. Model Constants Umf 0.0205 m/s mf 1.74*106 kg/m-4 mf 0.447 vc 0.87 c1
0.9984 c2
Z. B. Grbavcic, R. V. Garic, D. V. Vukovic, D. E. Hadzismajlovic, H. Littman, M. H. Morgan, and S. D. Jovanovic. Hydrodynamic modeling of vertical liquid solids flow. Powder Technology, 72(2):183–191, Oct

13. System Parameters k 0.00833 s-1 I 180 W/m2  300 m-1 KA 602430 ppm-1
C.ﾊM. So, M.ﾊY. Cheng, J.ﾊC. Yu, and P.ﾊK. Wong I
180
W/m2 
300
m-1
M.ﾊNazir, J.ﾊTakasaki, and H.ﾊKumazawa KA
602430
ppm-1
A.ﾊY. Khan. Titanium dioxide coated activated carbon xt
0.272
kgcon/kgpar
Kla 
9.24
$/kWh

14. Problem Statement Given: Adsorptive mass transfer rates
Contaminant degradation rates
The annular flowrate and inlet concentration
Target concentration
Minimize yi 10
ppm yo 1
GfA
0.5
GPM
Needs to be formal problem statement

15. Schematic of Algorithm
Physical Properties
Design Parameters
Sensitivity
Analysis
Operation specs
Sensitivity
Analysis
Interval analysis
Optimal design
and
operating conditions
Minimizing
objective function
Math Model

16. Results

17. Results cont.
Reverse

18. Results cont.

19. Optimal Design and OperationUV HA
52.65 in Gp
0.06 kg/s Gf
5-25 GPM D 
$/hr

20. Conclusion
Height of annular bed is insensitive to change in mass flowrate.
Operating at a low mass flowrate (<0.1 kg/s) allows for the most robust performance.
For the test system of TiO2/AC UV cost is high
Motivates for optimization of catalyst properties
i.e. density, UV adsorption, and kinetics
Model must be experimentally validated
Specifically the kinetics and mass transfer models

21. Acknowledgements Dr. Howard Littman Dr. Joel Plawsky
Dr. David Dziewulski (DOH and SUNY school of Public health)
Martin Research Group
RPI funding
Department of Defense
Department of defense
Do not acknowlae lealon or jphn
Add tom