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TRANSCRIPT
Numerical Study of the Self-ignition of
Tetrafluoroethylene in a 100-dm3-reactor
Fabio Ferrero , Robert Zeps, Martin Kluge
BAM Federal Institute for Materials Research and Testing
What is tetrafluoroethylene (TFE)?
• Tetrafluoroethylene (C2F4) is a colorless gas
INTRODUCTION
• TFE has a wide commercial relevance
• PTFE (Teflon®)
• PTFE Co-polymers
• TFE is a chemically unstable gas explosive decomposition
without oxidant (accidents in chemical plants*)
* Reza, A., Christiansen, E., A Case Study of a TFE Explosion in a PTFE Manufacturing Facility, Process Safety Progress, 26(1), 77-82 (2007)
• Focus: ignition of TFE caused by contact on hot surfaces
(self-ignition)
8442 FCc0.5FC
TFER molkJH 103
DIMERIZATION
REACTIONS
Main reactions
TFE at high pressure comes in contact with hot surfaces
TFE at high pressure comes in contact with hot surfaces
TFER molkJH 257
C(s)CFFC 442
8442 FCc0.5FC
TFER molkJH 103
DIMERIZATION
DECOMPOSITION
Main reactions
REACTIONS
2242 CFCFFC
26384 )()( CFeFCcFC
24263 )( CFFCcFC
)()( 6363 cFCeFC
4263284 )()( FCeFCCFcFC )(844242 cFCFCFC
42FC
2242 CFCFFC
26384 )()( CFeFCcFC
24263 )( CFFCcFC
)()( 6363 cFCeFC
4263284 )()( FCeFCCFcFC )(844242 cFCFCFC
42FC
*Bauer, S.H., Javanovic, S., The Pyrolysis of Octafluorocyclobutane - Revisited, International Journal of Chemical Kinetics, 30, 171-177 (1998)
Extended reaction net*
REACTIONS
100-dm³-autoclave
Properties: stainless steel 1200 kg 360° rotation 345 bar(a) at 20 °C
Measurements: temperature (up to 3 TC) pressure
EXPERIMENTS
100-dm³-autoclave
Properties: stainless steel 1200 kg 360° rotation 345 bar(a) at 20 °C
Measurements: temperature (up to 3 TC) pressure
EXPERIMENTS
Tests:
• p0 = 5, 10 and 20 bar(a)
• Twall,0 is varied
=> lowest Twall,0 with an ignition
100-dm³-autoclave
Properties: stainless steel 1200 kg 360° rotation 345 bar(a) at 20 °C
Measurements: temperature (up to 3 TC) pressure
EXPERIMENTS
Tests:
• p0 = 5, 10 and 20 bar(a)
• Twall,0 is varied
=> lowest Twall,0 with an ignition
Meshes (2D): only the TFE domain is computed
SIMULATIONS
Quality > 0.85
Fup=uut
u
2
Equations
0=ut
TPP STuρcTλ=t
Tρc
kCkkk
k SCuC=t
C
D
Tp sR/
SIMULATIONS
Chemical Engineering Module: - non-isothermal flow mode (chns)
- convection and conduction mode (chcc)
- convection and diffusion mode (chcd)
Momentum
Continuity
Mass transfer
Heat transfer
Ideal gas law
Horizontal Reactor
p0 = 11 bar(a)
T0 = 240 °C
Vertical Reactor
SIMULATIONS
p0 = 11 bar(a)
T0 = 240 °C
SIMULATIONS
T [°C] T [°C]
Horizontal Reactor
p0 = 11 bar(a)
T0 = 240 °C
t = 54 s
Vertical Reactor
p0 = 11 bar(a)
T0 = 240 °C
t = 54 s
MORE CRITICAL
Prediction accuracy of TFE ignition temperatures (MITD)
150 175 200 225 250 275 300
150
175
200
225
250
275
300
Vertical orientation
Horizontal orientation
+20%
MIT
D (
Ca
lcu
late
d)
[°C
]
MITD (Experimental) [°C]
-20%
Pressure range: 5-20 bar(a)
SIMULATIONS
• simulations of the self-ignition of TFE in a large scale vessel (100 dm³) were performed
• a good agreement with experimental data was observed
• in particular ignition temperatures of TFE were well predicted
• the model is considered validated for large geometries
CONCLUSIONS
QUESTIONS
Numerical Study of the Self-ignition of
Tetrafluoroethylene in a 100-dm3-reactor
Fabio Ferrero , Robert Zeps, Martin Kluge
BAM Federal Institute for Materials Research and Testing