ESTIMATION OF TIME TO MAXIMUM RATE UNDER ADIABATIC CONDITIONS (TMRad) USING KINETIC PARAMETERS DERIVED FROM DSC - INVESTIGATION OF THERMAL BEHAVIOR OF 3-METHYL-4-NITROPHENOL
1AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland, http://www.akts.com
2armasuisse, Science and Technology Centre, 3602 Thun, Switzerland
3Ciba Schweizerhalle AG, P.O. Box, 4002 Basel, Switzerland
4DSM Nutritional Products Ltd., Safety laboratory, 4334 Sisseln, Switzerland
5F. Hoffmann-La Roche Ltd, Safety laboratories, 4070 Basel, Switzerland
6Lonza AG, Safety Laboratory Visp, Rottenstr. 6, 3930 Visp, Switzerland
7Novartis Pharma AG, Novartis Campus, WSJ-145.8.54, 4002 Basel, Switzerland
8Syngenta Crop Protection Münchwilen AG, WMU 3120.1.54, 4333 Münchwilen, Switzerland
9Swiss Safety Institute, Schwarzwaldallee 215, WRO-1055.5.02, 4002 Basel, Switzerland
Abstract
Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal
behavior under any temperature profile. Presented paper describes the application of the advanced kinetic approach for the
determination of the thermal behavior also under adiabatic conditions occurring e.g. in batch reactors in case of cooling failure. The kinetics of the decomposition of different samples (different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal (few heating rates varying from 0.25 to 8.0 K/min) and isothermal (range of 200-260°C) modes. The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals. After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system, the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.
Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search (HWS) mode of operation of adiabatic calorimeters. The thermal safety diagram depicting dependence of Time to Maximum Rate (TMR) on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with F-factor amounting to 3.2. The influence of the F-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed. Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24 hrs characteristic for a sample with initial reaction progress amounting to zero.
Described estimation method can be verified by just one HWS-ARC, or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any F-factor. Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.
DETERMINATION OF SADT AND COOK-OFF IGNITION TEMPERATURE BY ADVANCED KINETIC ELABORATION OF DSC DATA
1AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 3,
3960 Siders, Switzerland
2armasuisse, Science and Technology, http://www.armasuisse.ch, 3602 Thun, Switzerland
3Nitrochemie Wimmis AG, http://www.nitrochemie.com, 3752 Wimmis, Switzerland
4Chilworth Technology, Inc., http://www.chilworth.com, 08532 New Jersey, USA
Abstract
The exothermic decomposition parameters of a single-base propellant were obtained using differential scanning calorimeter (DSC) tests conducted at various heating rates. The DSC signals were processed using the Friedman isoconversional method to compute activation energy as a function of conversion. There was excellent agreement between the experimental and the simulation plots, which confirms the validity of the kinetic model used to describe the propellant’s exothermic decomposition. The kinetic parameters and heat balance were subsequently analyzed and used for a simulation of cookoff experiments conducted at different experimental rates (heating rates 3.3 - 1.0 K/h and a heat-wait-search mode). This study presents a simulation of the propellant’s adiabatic behaviour Time to Maximum Rate (TMR) under adiabatic conditions (TMRad) and self-accelerating decomposition temperature (SADT). This study also illustrates and discusses the effect of a material’s thermal conductivity on the time to ignition at various heating modes.
View publication: DETERMINATION OF SADT AND COOK-OFF IGNITION TEMPERATURE BY ADVANCED KINETIC ELABORATION OF DSC DATA (pdf, 638 KB)
ADVANCED KINETICS-BASED SIMULATION OF TIME TO MAXIMUM RATE UNDER ADIABATIC CONDITIONS
1 AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 3, 3960 Siders, Switzerland
2 Janssen Pharmaceutica NV, http://www.jnj.com, 2340 Beerse, Belgium
3 Stazione Sperimentale per i Combustibili, http://www.ssc.it/, 20097 San Donato Milanese, Italy
4 armasuisse, Science and Technology, http://www.armasuisse.ch, 3602 Thun, Switzerland
Abstract
Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal
behavior under any temperature profile. Presented paper describes the application of the advanced kinetic approach for the
determination of the thermal behavior also under adiabatic conditions occurring e.g. in batch reactors in case of cooling failure.
The kinetics of the decomposition of different samples (different manufacturers and batches) of 3-methyl-4-nitrophenol were
investigated by conventional DSC in non-isothermal (few heating rates varying from 0.25 to 8.0 K/min) and isothermal (range of
200-260°C) modes. The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate
and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals. After
application of the heat balance to compare the amount of heat generated during reaction and its removal from the system, the
knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating
in adiabatic and pseudo-adiabatic conditions.
Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search (HWS) mode of operation of adiabatic
calorimeters. The thermal safety diagram depicting dependence of Time to Maximum Rate (TMR) on the initial temperature was
calculated and compared with the results of HWS experiments carried out in the system with Φ-factor amounting to 3.2. The
influence of the Φ-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed. Presented
calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24 hrs characteristic for a sample with
initial reaction progress amounting to zero.
Described estimation method can be verified by just one HWS-ARC, or by one correctly chosen ISO-ARC run of reasonable duration
by knowing in advance the dependence of the TMR on the initial temperature for any Φ-factor. Proposed procedure results in
significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at
the beginning of a process safety evaluation..
Keywords: Adiabatic Conditions, Methyl, Nitrophenol, DSC, Φ-Factor, Kinetics, Thermal Runaway, Time to Maximum Rate (TMR)
Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 163–173. If your institution has access, you may view this paper at:
http://dx.doi.org/10.1007/s10973-007-8866-1
EVALUATING SADT BY ADVANCED KINETICS-BASED SIMULATION APPROACH
1 AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 3, 3960 Siders, Switzerland
2 armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3 Nitrochemie Wimmis AG, http://www.nitrochemie.com, 3752 Wimmis, Switzerland
Abstract
Present study depicts the extension of the method of the application of the advanced kinetic description of the energetic materials decomposition by its combination with the exact heat balance carried out by numerical analysis and the determination of the Self-Accelerating Decomposition Temperature (SADT). Moreover, the additional parameters such as thermal conductivity of the self-reactive substances, the type of containers and insulation layers, and different temperature profiles of the surrounding environment were taken into consideration. The results of DSC experiments carried out with different heating rates in the range of 0.25-4°C/min were elaborated by the Thermokinetics software. The application the Thermal Safety software and the kinetics-based approach led to proper selection of experimental conditions for SADT testing. The applied approach enabled the simulation of such scenario as the thermal ignition of self-reactive chemicals conditioned previously for 12h at 80°C and exposed later isothermally for 8h to temperatures between 120-180°C. Described method can be used for analysis of possible development of runaway during storage or transport of dangerous goods (TDG) and containers, and subsequent choice of the conditions that can prevent an accident.
Keywords: Thermal decomposition kinetics, Isoconversional method, Upscaling of DSC data, Heat balance, SADT, Cook-off, Time to ignition, Transport of dangerous goods.
Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 153–161. If your institution has access, you may view this paper at:
http://dx.doi.org/10.1007/s10973-007-8865-2
THE SIMULATION OF THE THERMAL BEHAVIOR OF ENERGETIC MATERIALS BASED ON DSC AND HFC SIGNALS
1 AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 3, 3960 Siders, Switzerland
2 armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3 Nitrochemie Wimmis AG, http://www.nitrochemie.com, 3752 Wimmis, Switzerland
4 ISL, Institut franco-allemand de recherches de Saint-Louis, http://www.isl.eu, 68301 Saint Louis, France
5 CNES Centre National d’Etudes Spatiales, http://www.cnes.fr, 31401 Toulouse, France
Abstract
Two small calibre- and four medium calibre types of propellants were investigated non-isothermally (0.25-4 K/min) by Differential Scanning Calorimetry (DSC) in the range of RT-260°C and isothermally (60-100°C) by Heat Flow Calorimetry (HFC). The data obtained from both techniques were used for the calculation and comparison of the kinetic parameters of the decomposition process. The application of HFC allowed to determine the kinetic parameters of the very early stage of the reaction (reaction progress a below 0.02) what, in turn, made possible the precise prediction of the reaction progress under temperature mode corresponding to real atmospheric changes according to STANAG 2895. In addition, the kinetic parameters obtained from DSC data enabled determination of Self Accelerating Decomposition Temperature (SADT) and comparison of the predicted ignition temperature during slow cook-off with the experimental results. The study contains also the results of the calculation of the Time to Maximum Rate (TMRad) of the propellants under adiabatic conditions.
Keywords: energetic materials, thermal decomposition kinetics, SADT, cook-off, DSC, HFC, TMRad, time to maximum rate, adiabatic conditions.
Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 143–152. If your institution has access, you may view this paper at:
http://dx.doi.org/10.1007/s10973-007-8864-3
UP-SCALING OF DSC DATA OF HIGH ENERGETIC MATERIALS
1 Advanced Kinetics and Technology Solutions AKTS AG http://www.akts.com, TECHNO-Pôle, 3960 Siders, Switzerland
2 armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3 Nitrochemie Wimmis AG, http://www.nitrochemie.com, 3752 Wimmis, Switzerland
Abstract
Differential scanning calorimetry (DSC) carried out with few heating rates was applied in the studies of the thermal properties of four energetic materials: EI® propellant, high explosive PBXW-17, pyrotechnic mixtures with composition B/KNO3 (50:50) and B/KNO3 (30:70). DSC signals, after optimization of the baseline, were used for the calculation of the kinetic parameters (KP) of the decomposition process applying advanced kinetic software designed by AKTS. The determination of the kinetic parameters was based on the differential iso-conversional method of Friedman. The correctness of the estimation of KP was checked by the comparison of the experimental and predicted courses of the decomposition. The slow cook-off experiments of above mentioned energetic materials were carried out with a heating rate of 3.3°C h–1. For the simulation of the experimental results, the heat balance based on the finite element analysis (FEA) was applied together with the advanced kinetic description of the reaction. The comparison of the experimental and simulated data indicates that applied procedure resulted in a very good prediction of the temperature of the ignition. Application of commonly used, simplified assumptions concerning the mechanism of the decomposition (such as 1 st or n th order mechanisms) led to significantly worse prediction of the cook-off temperatures.
Keywords: adiabatic runaway, cook-off, ignition, kinetics, safety, thermal ageing, thermal hazards, TMRad
Journal of Thermal Analysis and Calorimetry, Vol. 85 (2006) 1, 195–202. If your institution has access, you may view this paper at:
http://dx.doi.org/10.1007/s10973-005-7388-y
THE PREDICTION OF THERMAL STABILITY OF SELF-REACTIVE CHEMICALS
1Advanced Kinetics and Technology Solutions AKTS AG http://www.akts.com, TECHNO-Pôle, 3960 Siders, Switzerland
2armasuisse, Science and Technology Centre, http://www.armasuisse.ch, 3602 Thun, Switzerland
3University of Applied Sciences of Western Switzerland, http://www.eif.ch, 1705 Fribourg, Switzerland
Abstract
An advanced study on the thermal behaviour of double base (boost and sustain propellant) rocket motor used in a ground to air missile has been carried out by differential scanning calorimetry (DSC). The presence of two propellants as well as the different experimental conditions (open vs. closed crucibles) influence the relative thermal stability of the energetic materials. Several methods have been presented for predictions of the reaction progress of exothermic reactions under adiabatic conditions. However, because decomposition reactions usually have a multi-step nature, the accurate determination of the kinetic characteristics strongly influences the ability to correctly describe the progress of the reaction. For self-heating reactions, incorrect kinetic description of the process is usually the main source of serious errors for the determination of the time to maximum rate under adiabatic conditions (TMRad). It is hazardous to develop safety predictive models that are based on simplified kinetics determined by thermoanalytical methods. Applications of finite element analysis (FEA) and accurate kinetic description allow determination of the effect of scale, geometry, heat transfer, thermal conductivity and ambient temperature on the heat accumulation conditions. Due to limited thermal conductivity, a progressive temperature increase in the sample can easily take place resulting in a thermal explosion. Use of both, kinetics and FEA [1], enables the determination of the reaction progress and temperature profiles in storage containers. The reaction progress and temperature can be determined quantitatively at every point in time and in space. This information is essential for the design of containers of self-reactive chemicals, cooling systems and the measures to be taken in the event of a cooling failure.
Journal of Thermal Analysis and Calorimetry, Vol. 80 (2005) 91–102. If your institution has access, you may view this paper at:
http://dx.doi.org/10.1007/s10973-005-0619-4
