determination of sadt sadt and tmrad by advanced...
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Determination of Determination of SADTSADT and and TMRadTMRadby Advanced Kinetic Elaboration of DSC Databy Advanced Kinetic Elaboration of DSC Data
20082008Mary Kay OMary Kay O’’Connor Connor ProcessProcess SafetySafety CenterCenter
International SymposiumInternational SymposiumBeyondBeyond RegulatoryRegulatory ComplianceCompliance, , MakingMaking SafetySafety Second NatureSecond Nature
OctoberOctober 2828--29, 200829, 2008Hilton Hilton ConferenceConference CenterCenter
CollegeCollege Station, Texas, USAStation, Texas, USA
B. B. RoduitRoduit11, P. , P. FollyFolly22, A. , A. SarbachSarbach22, B. , B. BergerBerger22, J. , J. MathieuMathieu22, M. , M. RaminRamin33, B. , B. VogelsangerVogelsanger33,R. ,R. KwasnyKwasny4411 AKTS AG, AKTS AG, TECHNOArkTECHNOArk 3, 3960 3, 3960 SidersSiders, Switzerland, Switzerland
22 armasuissearmasuisse, Science and Technology, 3602 , Science and Technology, 3602 ThunThun, Switzerland, Switzerland33 NitrochemieNitrochemie WimmisWimmis AG, 3752 AG, 3752 WimmisWimmis, Switzerland, Switzerland4 4 Chilworth Technology, Inc., 08532 New Jersey, USAChilworth Technology, Inc., 08532 New Jersey, USA
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Determination of the kinetic Determination of the kinetic parameters: simplified reaction modelparameters: simplified reaction model
)1(
RTE expA
dtd
E = constantSimplified model f(a) = (1-a)n
Where n-reaction order is assumed to be 0, 1 or 2
n
Still commonly used simplification: ‘ Let‘s assume that the reaction is of n-th order ‘
pre-exponential factoractivation energy
reaction progressreaction rate
reaction order
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Determination of the kinetic Determination of the kinetic characteristicscharacteristics
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Problem of interpretation Problem of interpretation of an observationof an observation
What do you see ?What do you see ?
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Differential Differential isoconversionalisoconversional method of Friedmanmethod of Friedman
)( fRTE expA
dtd
Rate of the reaction is expressed by the Arrhenius equationRate of the reaction is expressed by the Arrhenius equation
TREConst
dtd 1ln
IsoconversionalIsoconversional methodsmethods (model free):(model free):
There are 3 main modifications of There are 3 main modifications of isoconversionalisoconversional method:method:
-- Differential (Friedman)Differential (Friedman)
-- Integral (FlynnIntegral (Flynn--OzawaOzawa--Wall)Wall)
-- Advanced integral based on nonAdvanced integral based on non--linear procedure (linear procedure (VyazovkinVyazovkin))
Differential isoconversional method of FriedmanDifferential isoconversional method of Friedman
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Differential Differential isoconversionalisoconversional method of Friedmanmethod of Friedman
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TREConst
dtd 1ln
11
22
33
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Baseline optimizationBaseline optimization
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STANAG 2895 STANAG 2895 ––climatic categoriesclimatic categories
STANAG 2895STANAG 2895A2 (Hot dry)A2 (Hot dry)
Beijing Beijing
0
10
20
30
40
50
60
0 2 4 6 8 10time /year
tem
pera
ture
/°C
inventedinvented exampleexample
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UpUp--scaling of DSC resultsscaling of DSC results
UpUp--scalingscaling
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UpUp--scaling of DSC resultsscaling of DSC results
Example of adiabatic runaway scenarioExample of adiabatic runaway scenario
Before :Before :
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UpUp--scaling of DSC resultsscaling of DSC results
Example of adiabatic runaway scenarioExample of adiabatic runaway scenario
After :After :
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ARC experiments ARC experiments underunder(pseudo(pseudo--) adiabatic conditions) adiabatic conditions
Temperature and pressure dependence on time recorded during ARC Temperature and pressure dependence on time recorded during ARC HWS HWS experiment at air pressure of 1.8 MPa experiment at air pressure of 1.8 MPa
Detection limit = 0.02 K/minDetection limit = 0.02 K/min
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Link between kinetics Link between kinetics and TMR under adiabatic conditionsand TMR under adiabatic conditions
Determination of time to maximum rateDetermination of time to maximum rateunder adiabatic conditions (TMRad)under adiabatic conditions (TMRad)
=0=0 Or Or ==
=1=1 ==TTadad
From DSCFrom DSC
adiabatic conditionsadiabatic conditions
> 1000 kg> 1000 kg
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adiabaticadiabatic induction time (h)induction time (h)
criti
cal
criti
cal s
tarti
ngst
artin
gte
mpe
ratu
rete
mpe
ratu
re(( °°
C)
C)
Determination of TMRadDetermination of TMRad24h24h
Thermal safety diagram: Thermal safety diagram: Dependence of Dependence of TMRadTMRad on starting temperaturestarting temperature
T = 90T = 90°°CC TMRadTMRad = 24 hours= 24 hours
UNSAFE zoneUNSAFE zone
SAFE zoneSAFE zone
=0=0Or Or ==
UWithWith
14time (h)time (h)
tem
pera
ture
tem
pera
ture
(( °°C
)C
)Determination of TMRadDetermination of TMRad24h24h
Adiabatic runaway scenario: Adiabatic runaway scenario: Time to Maximum Rate under adiabatic conditions Time to Maximum Rate under adiabatic conditions
TT00 = 90= 90°°CC TMRadTMRad = = ~~ 24 hours24 hours
TTadad = 1866= 1866°°CC
UNSAFE zoneUNSAFE zone
SAFE zoneSAFE zone
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CookCook--offoff
Example of cookExample of cook--off experimentoff experiment
Before :Before :
After :After :
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CookCook--offoff and SADTand SADT
??HeatHeat
BalanceBalance
DecompositionDecomposition KineticsKinetics
Thermal Thermal ConductivityConductivity
HeatHeatBalanceBalance
Thermal Thermal ConductivityConductivity
??DecompositionDecomposition
KineticsKinetics
DSCDSC
??HeatHeat productionproduction HeatHeat removalremoval
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Heat Heat balancebalance under nonunder non-- adiabatic conditionsadiabatic conditions
wallwall
centercenter
reactioninput output accumulationheat
conductedin
heatgenerated
within
heatconducted
out
change in energystoredwithin
+ +=
-
Kinetics / DSCKinetics / DSC
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CookCook--off experimentoff experiment
BeforeBefore
AfterAfter
Tsurrounding
(Experimental)
3.3 K/h3.3 K/h
?
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Simulation of time to ignition for 0.1 < Simulation of time to ignition for 0.1 <
< 1 < 1 W(mW(m·· K)K)
CookCook--off experimentoff experiment
BeforeBefore
AfterAfter
Tsurrounding
(Experimental)
3.3 K/h3.3 K/h32.2 h32.2 h 34.3 h34.3 h
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Tsurrounding
(Experimental)
CookCook--off experimentoff experiment
BeforeBeforeAfterAfter
1 K/h1 K/h
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Simulation of time to ignition for 0.1 < Simulation of time to ignition for 0.1 <
< 1 < 1 W(mW(m·· K)K)
Tsurrounding
(Experimental)
CookCook--off experimentoff experiment
BeforeBeforeAfterAfter
1 K/h1 K/h
25.2 h25.2 h 33.4 h33.4 h
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Tsurrounding
(Experimental)
CookCook--off experimentoff experiment
BeforeBefore
AfterAfter
HeatHeat--WaitWait--SearchSearch
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Simulation of time to ignition for 0.1 < Simulation of time to ignition for 0.1 <
< 1 < 1 W(mW(m·· K)K)
Tsurrounding
(Experimental)
CookCook--off experimentoff experiment
BeforeBefore
HeatHeat--WaitWait--SearchSearch49 h49 h 120 h120 h
AfterAfter
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Wall T (calculated)
Center T (Calculated)te
mpe
ratu
re /°
CSimulation of ignition under Simulation of ignition under
HeatHeat--WaitWait--SearchSearch temperature mode applying temperature mode applying = 0.32 W/m/K = 0.32 W/m/K
Temperature mode: H-W-STime to ignition (exp): 110.4 hTime to ignition (exp): 110.4 hIgnition temp. (exp): 116.4Ignition temp. (exp): 116.4°°CCOptimal Optimal : 0.320 W/m/K: 0.320 W/m/K
time /h
Tsurrounding
(Experimental)
Ignition temperatureIgnition temperature
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The concept of SelfThe concept of Self--Accelerating Accelerating Decomposition Temperature (SADT)Decomposition Temperature (SADT)
UN-Regulations…T (°C)
t (h)
SADT SADT is defined asis defined as ““the lowest environment temperature at which overheat the lowest environment temperature at which overheat in the middle of the specific commercial packing in the middle of the specific commercial packing
exceeds 6exceeds 6°°C after a laps of period of seven days (168 hours) or lessC after a laps of period of seven days (168 hours) or less””..This period is measured from the time when the packaging center This period is measured from the time when the packaging center temperature temperature
reaches 2reaches 2°°C below the surrounding temperature.C below the surrounding temperature.
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Determination of SelfDetermination of Self--Accelerating Accelerating Decomposition Temperature (SADT)Decomposition Temperature (SADT)
SADT is 84SADT is 84°°C. C. This temperature is the lowest environment temperature at which This temperature is the lowest environment temperature at which overheat in the middle of the overheat in the middle of the specific packaging exceeds 6 specific packaging exceeds 6 °°C (C (T6) after a lapse of the period of seven days (168 hours) or T6) after a lapse of the period of seven days (168 hours) or less. This period is measured from the time when the packaging cless. This period is measured from the time when the packaging centre temperature reaches entre temperature reaches
2 2 °°C below the surrounding temperature. This overheat of 6C below the surrounding temperature. This overheat of 6°°C occurs after about 5 days.C occurs after about 5 days.
wallwall
centercenter
7 days or less7 days or less
overheat = 6overheat = 6°°CC
T T surroundingsurrounding --22°°CC
surrounding surrounding temperature temperature
SADT = 84SADT = 84°°CC
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0.1 1 10 100
75
80
85
90
95
100
105
110
OOO
OO
O
O
100 L50 L25 L10 L5 L1 L0.35 L
SA
DT
/°C
/W/(m·K)
Determination of SelfDetermination of Self--Accelerating Accelerating Decomposition Temperature (SADT)Decomposition Temperature (SADT)
SADT as a function of the thermal conductivity SADT as a function of the thermal conductivity and sample volume expressed in L. and sample volume expressed in L. The circles represent the simulation of SADT when applying the The circles represent the simulation of SADT when applying the value taken from the value taken from the
HH--WW--SS--mode simulationmode simulation
= 0.32 W/m/K= 0.32 W/m/K
0.35L
25L50L
10L
Sample
volume change
1L
5L
100L
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0.1 1 10 100
75
80
85
90
95
100
105
110
OOO
OO
O
O
100 L50 L25 L10 L5 L1 L0.35 L
SA
DT
/°C
/W/(m·K)
Determination of SelfDetermination of Self--Accelerating Accelerating Decomposition Temperature (SADT)Decomposition Temperature (SADT)
SADT for various the sample volume expressed in L. SADT for various the sample volume expressed in L. The circles represent the simulation of SADT when applying the The circles represent the simulation of SADT when applying the value taken from the value taken from the
HH--WW--SS--mode simulationmode simulation
= 0.32 W/m/K= 0.32 W/m/K
0.35L
25L50L
10L
Sample
volume change
1L
5L
100L
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ConclusionsConclusions
Independent of the mass of the sample investigated in any Independent of the mass of the sample investigated in any thermoanalyticalthermoanalytical experiment, the correct description of the experiment, the correct description of the
time to thermal ignition of a decomposition reaction requires time to thermal ignition of a decomposition reaction requires the knowledge of the knowledge of two important parameters two important parameters
(i) the kinetics of the investigated reaction and (i) the kinetics of the investigated reaction and (ii) the heat balance of the system.(ii) the heat balance of the system.
Depending on the mass of the sample both these Depending on the mass of the sample both these parameters differently contribute to the reaction progress.parameters differently contribute to the reaction progress.
‘‘Safety through calculations not by accidentsSafety through calculations not by accidents’’
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Advanced Kinetics and Technology Solutions
AKTS AG, C. Borgeat, C. Luyet, L.Xia, N. Solioz, JG. Pont AKTS AG, C. Borgeat, C. Luyet, L.Xia, N. Solioz, JG. Pont
armasuisse, Dr. P. Folly, Dr. A.Sarbach and B. Bergerarmasuisse, Dr. P. Folly, Dr. A.Sarbach and B. BergerSwiss Federal office of Public Health, Dr. V. DudlerSwiss Federal office of Public Health, Dr. V. Dudler
Univ. of Western Switzerland, Prof. J.N. Aebischer, Univ. of Western Switzerland, Prof. J.N. Aebischer, S. Gomez, B. AlonsoS. Gomez, B. Alonso
Swiss Institute of Safety and Security,Swiss Institute of Safety and Security,Dr. P. Reuse, Prof. F. Stoessel, Dr. H. Fierz Dr. P. Reuse, Prof. F. Stoessel, Dr. H. Fierz
Nitrochemie Wimmis AG, Dr. M. Ramin, Dr. U. SchNitrochemie Wimmis AG, Dr. M. Ramin, Dr. U. Schäädeli, deli, Dr. B. VogelsangerDr. B. Vogelsanger
Acknowledgements Acknowledgements Our partners and friendsOur partners and friends
ChilworthChilworth Technology, Inc., Technology, Inc., Dr. R. KwasnyDr. R. Kwasny