2016 ANSYS Convergence Conference30 June, Electra Palace Hotel, Athens, Greece
ANSYS Hall of Fame 2016 Competition Winner - Academic: Investigation of 2-phase evaporative reacting flows in micro-scale
Dr. Nikolaos Nikolopoulos, PhD cand. Ilias Malgarinos, and Prof.Manolis Gavaises
http://www.ansys.com/Other/Hall-of-Fame/CUL
Presentation Outline
Activities Ideas Possibilities
Current Activities
Droplet Dynamics
Fluidized Beds
Ideas (Prospects)
CFD application prospects in FCC industry
Ideas for collaboration
Ansys Convergence 2016, Slovenia
Droplet Dynamics
Activities Ideas Possibilities
Drop-gas Solid Surface Phase Change Reactions+ + +
Validated 2-phase flow model VOF in wide range of cases
Ansys Convergence 2016, Slovenia
Activities Ideas Possibilities
Model Features
Navier-Stokes Momentum-Continuity
Volume of Fluid Method (VOF) for interphase tracking
Phase change Evaporation Model
Drop motion
Dynamic local refinement
Droplet Dynamics
Surface Reactions
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
FCC (Fluid Catalytic Cracking), from large scale to micro scale
Large Scale(FCC reactor)
Meso Scale(injection zone)
Micro Scale(drop-particle collisions)
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Why study the micro scale?
Investigate the reasons for catalyst pore blocking (due to non-evaporated liquid or coke formed) originating in direct solid-liquid contact
Improve selectivity
Optimize injection strategy
Injection is a micro-scale phenomenon
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Parameters investigatedParticle Droplet Gas
Position static moving
D (μm) 75 75-150
U (m/s) 15-30
T (K) 800-1000 550 800
P (atm) 2
Constant conditionsParameters
Cracking Pathway assumed Cracking rates from
Gianetto et al. (1994)
Gianetto, A., et al., Fluid Catalytic Cracking
Catalyst for Reformulated Gasolines. Kinetic
Modeling. Industrial & Engineering Chemistry
Research, 1994. 33(12): p. 3053-3062.C25H52(l) C25H52(g) C7H16(g)
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Application in FCC industry
Activities Ideas Possibilities
Case 1 (2D), 1 drop – 1 particleDd = Dp 2D
Effect of particle T on collision outcome
thin liquid expanding radially
torus breakup
τ=0.1 τ=0.7 τ=1.1 τ=1.7
Uo = 15m/s
10
00
K8
00
K
Tp
Formation of vapour layer
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
2D
encapsulation
Dd = 2Dp
15
m/s
Tp = 800K Effect of impact velocity on collision outcome
Case 1 (2D), 1 drop – 1 particle
30
m/s
Uo τ=0.1 τ=0.5 τ=1.0 τ=1.4
thick (compared to the previous where we had a “thin”) ejecta sheet - expanding radially
under specific conditions may lead to satellite droplets detachment
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Vapour layer prediction- a decisive parameter (Leidenfrost phenomenon)
Drop is levitated by a vapour layer on hot catalysts2D
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Cracking Predictions
Hotter catalysts promote cracking reactions/gasoline production
Low impact velocity promotes cracking reactions/gasoline production
2D
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Application in FCC industry
Activities Ideas Possibilities
Droplet info
Small over large droplets (compared to catalytic particles) evaporate faster and cool down slightly in the process
2D
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Case 2 (3D), 1 drop – 1 particle 3D
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Vapour layer prediction-Leidenfrost phenomenon
Drop is levitated by a vapour layer on hot catalysts3D
h
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Droplet break-up mechanism in 3D 3DDd = Dp
Uo = 15m/s
Tp = 1000K
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Case 3 (3D), 1 drop – many particles 3DDd = 2Dp
Uo = 30m/s
Tp = 1000K
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Droplet impact onto a cluster
Many different liquid shapes (ligaments, sheet, fingers)/ Gasoline prediction
3DDd = 2Dp
Uo = 30m/s
Tp = 1000K
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Cluster formations promote cracking reactions/gasoline production compared to 1drop-1particle collisions
3DDroplet impact onto a cluster
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Application in FCC industry
Activities Ideas Possibilities
Droplets on clusters evaporate faster and heat up in the process3DDroplet impact onto a cluster
Ansys Convergence 2016, Slovenia
CUL-CERTH-video-Malgarinos.mpg
Application in FCC industry
Activities Ideas Possibilities
3DExhibited Dynamics
Application in FCC industry
Activities Ideas Possibilities
Case 4 (2D), 4 chain drops – 1 particle 2D
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Application in FCC industry
Activities Ideas Possibilities
Case 4 (2D), 4 chain drops – 1 particle 2D Solution of particle cells for prediction of particle cooling from impact
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Particle cooling characterization(4 chain drops on 1 particle)
Similar trend of particle temperature decrease for different chain impact periods and initial particle temperatures
2D
a dimensionless character for time periods up to 12 μs (800 K) a dimensionless character for time periods up to at least 24 μs (1000 K)
Ansys Convergence 2016, Slovenia
Application in FCC industry
Activities Ideas Possibilities
Wall heat flux prediction for different chain impact periods (6, 12, 24 μs between each impact) and initial particle temperatures
Particle cooling characterization(4 chain drops on 1 particle)
2D
a higher WHF for 1000 K (compared to 800 K) – this controls the necessary regeneration rate of catalytic particles
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Fluidized Beds
Activities Ideas Possibilities
Fluidized bed modeling
CERTH/CPERI Expertise
10 Year Experience in Fluidized Bed simulation
Hydrodynamic simulations
Reacting Flows
Full-loop simulations
Custom built model (EMMS) for the formation of clusters
Ansys Convergence 2016, Slovenia
CFD application in FCC industry
Activities Ideas Possibilities
FCC (Fluid Catalytic Cracking), large scale reactors
• Investigate back-mixing effects• Investigate Feed spray arrangement; Optimize catalyst / liquid oil
mixing• Use of micro-scale results to predict accurately droplet / catalytic
particles fluid mechanics
Ansys Convergence 2016, Slovenia
CFD application in FCC industry
Activities Ideas Possibilities
FCC (Fluid Catalytic Cracking), micro scale
• Help in minimization of coke deposits in the feedstock injection zone originating from droplet-particle direct contact
• Investigate cooling rate for particle cluster• Identify configuration which promote light molecule gas yields
and catalytic particle temperature reduction
Ansys Convergence 2016, Slovenia
Experiments? Correlate particle insertion temperature with deactivated catalyst rate in outlet
Collaboration
Activities Ideas Possibilities
Internal Meeting
Experiments? Bring closer the region of injection with the region of particle insertion for increased possibility of drop levitation. Correlate injection/particle insertion regions overlapping with deactivated catalyst rate in outlet
Experiments? Find the optimum temperature of droplet injection for maximization of evaporation rate. Correlate droplet T with deactivated catalyst number in outlet
CERTH CFD competenciesCollaboration with Industrial partners
CERTH CFD competenciesPF and FB combustion
Fluent commercial code (licenses for parallel processing), fully validated UDFs (PF
and FB boilers)
New cluster computing system for parallel processing
House built validated developed models integrated in ANSYS/Fluent:
Char combustion
Devolatilization
Boudouard reaction
Radiation
NOx emissions
Drag Scheme (EMMS)
Full-loop simulation
Reacting flow
Homogeneous and
heterogeneous reactions
NOx emissions
Fluidized Bed TechnologyPulverized alternative fuel Technology
(WRF/SRF, Sludge, Biogenic Fuels)\
Numerical Grid of 2.5 million tetrahedral cells (High computational cost) The true geometry is fully respected. Detailed design of burners
Primary air
Secondary air
Burner wall
OFA
Labels
Recircualation
Ducts
Oil burners
Ag. Dimitrios PP
CERTH CFD competenciesAn example of a Greek PF boiler
CERTH CFD competenciesAn example of a German FB reactor
- The EMMS scheme developed increases the accuracy of the model especially in the dense
bottom region which is hard to model, and in which the majority of CO2 capture takes place.
CFD modeling of plexi-glass cold model (Carbonator) of USTUTT
Real geometry RVE RVE with Backstays
Wall heat flux as a BC
Anisotropic stiffness matrix (xml file)
Far-Field Analysis
CERTH CFD competenciesFEM tubes analysis in a German PP
Far-Field stress/strain fields Near-Field stress field
Near-Field Analysis
CERTH CFD competenciesFEM tubes analysis in a German PP
Thank you for your attention!
Activities Ideas Possibilities
The European Commission for funding this work, by the Marie Curie Fellowship (FP7-PEOPLE-2012-IEF), GA No 329500 entitled as “Non Flat
Impingement” is gratefully acknowledged
Appendix
Adaptive local grid refinement
Saves computational cost Increases accuracy at the interface
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