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CFD Lagrangian Multiphase Simulation Applied to Dust Explosion
Characterization
Authors: Daniel Vizcaya, Carlos Murillo, Nathalie Bardin-Monnier,
Olivier Dufaud, Laurent Perrin, Nicolás Ratkovich & Felipe Muñoz
Contact: Daniel Vizcaya ([email protected])
1
Speaker: Hugo Pineda
Content
1. Introduction to dust explosions
2. Explosivity Parameters and Equipment
3. Simulation
4. Results
5. Conclusiones and Future Work
2
1. Introduction to dust explosions: Imperial Sugar Case
Place: Port Wentworth, Georgia, USA
Date: February 7, 2008.
Process: Sugar refinery.
Combustible: Sugar.
Mean Particle size (m): 23
Pmax (bar): 7.5
MEC (g/m3): 95
Kst (bar m/s): 139
Impact:
• 14 fatalities.
• 36 injured.
• Process plant total destruction.3
Vorderbrueggen (2011)
1. Introduction to dust explosions
4
Eckhoff (2009)
1. Introduction to dust explosions
5
2. Explosivity parameters: Maximumpressure and maximum rate of pressure rise
6
Typical pressure profile of an explosion on the 20 L Sphere
Dahoe et al. (2001)
2. Explosivity parameters: MinimumExplosivity Concentration (MEC)
7
Eckhoff (2009)
Maize Starch Characterization
2. Explosivity parameters: Particle Size
8
Eckhoff (2009)
Aluminium Dust in Air
2. Explosivity parameters: Turbulence level
9Eckhoff (2009)
Lycopodium in Air
10
𝐾𝑠𝑡 =𝑑𝑃
𝑑𝑡𝑉1/3
Is a severity index developed from the maximum rate of
pressure rise and volume-invariant.
Risk Level Kst (bar m/s) Explosion Description
ST 1 1-200 Weak
ST 2 201-300 Strong
ST 3 > 300 Very Strong
2. Explosivity parameters: Deflagration Index
Table 1. Risk level associated to Deflagration Index
11
𝐾𝑠𝑡 =𝑑𝑃
𝑑𝑡𝑉1/3
Is a severity index developed from the maximum rate of
pressure rise and volume-invariant.
Material Mean ParticleSize
Concentration Kst (bar m/s)
Starch 10 105 189
Polyethylene 63 25 267
Phenolic Resin 40 50 165
2. Explosivity parameters: Deflagration Index
2. Dust explosion characterization equipment
12
• MEC from nominal concentration.
• Maximum pressure (Pmax).
• Maximum rate of pressure rise (dP/dtmax).
20 L Sphere 1 m3 Vessel
𝐾𝑠𝑡 =𝑑𝑃
𝑑𝑡𝑉1/3
13
2. Deflagration Index
Dahoe et al. (2001)
[13] 14
20 L Sphere 1 m3 Vessel
Dust containerpressure (barg)
20 20
Ignition Time (ms) 60 200
Ignition Energy (kJ) 10 10
Type of nozzle Rebound Annular
Type of flammabledust
High densities All densities
Table 2. Comparison between dust explosion characterization equipments
2. Dust explosion characterization equipment: Comparative Table
15
2. Experimental Studies
Dahoe et al. (2001)
• To develop a CFD multiphase flow to evaluate the dispersionphenomena of flammable dust within the 20 L Sphere understandard test conditions.
• To evaluate the dust concentration at ignition point on themoments previous to the explosion.
• To evaluate the turbulence level during the dispersion of thedust.
• To evaluate the particle distribution within the domain takinginto account the particle size.
16
3. Objectives
17
3. Simulation: General Geometry
Canister
Sphere
Igniters
Nozzle
Nozzle Vertical Cut
18
3. Simulation: Mesh
Models:
• Polyhedral mesher
• Advancing Layer Mesher
• Surface Remesher
Principal Reference Values:
• Number prism layers: 2
• Prism Layer Thickness: 0.036 mm
• Minimum Surface Size: 0.2 mm
Mesh Results:
• Cells: 7,316,852
• Faces: 51,224,435
• Verts: 43,619,275
19
3. Simulation: Mesh
Velref > 400 m/s
• Implicit Unsteady.– Time Step: 1 ms
– Temporal Discretization: 2nd Order
• Compressible Gas: Peng-Robinson
• Lagrangian Multiphase
• Detached Eddy Simulation
20
3. Simulation: Principal Models
• Lagrangian Multiphase:– Material: Starch– Models:
• Constant density: = 610 kg/m3
• Drag Force• Material Particles• Pressure Gradient Force• Spherical Particles
• Injector:– Mass Flow Rate: 6 kg/s for t <
0.2 ms– Number of Parcels: 2.2e+06– Particle Size Distribution from
laser diffraction (Table 3)
21
3. Simulation: Principal Models
Table 3. Particle Size Distribution from laser
diffraction
0
0.1
0.2
0.3
0.4
Mas
s Fr
acti
on
Particle Size (μm)
Particle Size Distribution
22
3. Simulation: Initial Conditions
23
4. Results: Influence of iterations
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 5 10 15 20
Pre
ssu
re (
bar
)
Time Step
Pressure profile
250 Iter
1000 Iter
Experimental results
24
4. Results: Computational cost
0
50
100
150
200
0 5 10 15
Sim
ula
tio
n t
ime
(h
)
Time Step
Computational Cost
250 iter
1000 iter
• Windows Server 2008 – 64-bit
• Processor: Intel ® Xeon ® X5060 @ 2.67GHz
• RAM; 40 Gb
25
4. Results: Particle flow
26
4. Results: Particle flow
27
4. Results: Particle diameter for 1000 iter
• STAR-CCM+® was used to developed a multiphase lagrangianflow in order to simulate the flammable dust dispersionwithin the 20 L sphere.
• The number of Maximum Inner Iterations has a significantimpact on the results as well as on the computational cost.
• The nozzle disperses correctly the dust within the domain.However, the smaller particles tends to the walls and thebigger ones to the center of the sphere.
• In order to model correctly the behavior of the flow, and dueto the geometry high complexity, it was necessary toimplement the DES turbulence model.
28
5. Conclusions
• The Maximum Inner Iterations will be increased to 1500.
• The simulation time will be 120 ms in order to evaluate abetter ignition time for the standard test.
• The use of cohesion models to represent particlefragmentation and agglomeration will be added.
• Another types of nozzle will be simulated in order to evaluatethe dust homogeneity within the sphere.
29
5. Future Work
CFD Lagrangian Multiphase Simulation Applied to Dust Explosion
Characterization
Authors: Daniel Vizcaya, Carlos Murillo, Nathalie Bardin-Monnier,
Olivier Dufaud, Laurent Perrin, Nicolás Ratkovich & Felipe Muñoz
Contact: Daniel Vizcaya ([email protected])
30
Speaker: Hugo Pineda
7. BIBLIOGRAFHY
"ISO 6184/1," Explosion Protection Systems - Part 1: Determination of Explosion
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W. Bartknecht, "Explosions: Course, Prevention, Protection," 1981.
W. Bartknecht, "Ignition capabilities of hot surfaces and mechanically generated
sparks in flammable gas and dust/air mixtures," 1987.
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V. Di Sarli, P. Russo, R. Sanchirico, and A. Di Benedetto, "CFD simulations of dust
dispersion in the 20 L vessel: Effect of nominal dust concentration," Journal of
Loss Prevention in the Process Industries, vol. 27, pp. 8-12, 2014.
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technology," Journal of Loss Prevention in the Process Industries, vol. 22, pp. 105-
116, 2009.
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31
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C. Murillo, O. Dufaud, N. Bardin-Monnier, O. López, F. Munoz, and L. Perrin, "Dust
explosions: CFD modeling as a tool to characterize the relevant parameters of the
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comparison and analysis of the discrepancies," Journal of Loss Prevention in the
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R. Siwek, "20-L Laborapparatur für die Bestimmung der Explosionskenngrößen
brennbarer Stäube," Thesis, 1977.
J. B. Vorderbrueggen, "Imperial sugar refinery combustible dust explosion
investigation," Process Safety Progress, vol. 30, pp. 66-81, 2011.
32
7. BIBLIOGRAPHY