(47ch) Sensitivity Analysis of Variables Affecting the Runaway Decomposition of Dicumyl Peroxide

Dycumil Peroxide (DCP) is widely used as an initiator, hardener and as a cross linking agent in the petrochemical industry. The use of this peroxide poses an intrinsic risk due to its reactivity and the possibility of its highly exothermic self-decomposition and subsequent runaway reaction, which is accompanied by a rapid rate of temperature and pressure increase.

 The hazards associated with the process, transport and storage of DCP are clearly reflected by the frequent incidents that have occurred in Asia in the last two decades: Taiwan (2008) ¹, Taiwan (2003) ², Japan (1999) and Taiwan (1988)¹. Though the accidents associated to DCP have not led to any fatality, it is important to be aware of its decomposition properties so as to prevent further incidents and major consequences.

 Emergency relief systems are the most commonly selected measure to protect reactors from thermal explosions (CCPS, 1998³). The main advantages of their use are the independence from the control system and passivity (and therefore reliability and robustness). However, the exiting relief sizing methods are consolidated mainly in the case of vapor systems (in which the relief operation is usually enough to cool down the reacting mixture), leading to oversizing in the case of untempered gassy systems (such as the decomposition reaction of DCP⁴).

 In the present work, the results of adiabatic experiments using two different calorimeters (PHI TEC I and PHI TEC II) are presented. A sensitivity analysis around the equipment configuration (open and close cell), the concentration of the peroxide (diluted in2,2,4-Trimethyl-1,3-pentanediol diisobutyrate), initial fill level, starting pressure and phi factor on the different runaway parameters (maximum pressure, gas generation, maximum rise of temperature and pressure rates, time to maximum rate and onset temperature) is discussed. Finally vent sizing calculations are performed using different methodologies available in the open literature. Based on the calorimetric data and the vent sizing calculations the limitations of these methodologies are discussed and recommendations for the proper vent sizing and safe scale up of the system studied are made.

 References

1. Shen S-J, Wu S-H, Chi J-H, Wang Y-W, Shu C-M. Thermal explosion simulation and incompatible reaction of dicumyl peroxide by calorimetric technique. Journal of Thermal Analysis and Calorimetry. 2010;102(2):569–577. doi:10.1007/s10973-010-0916-4
2. Wu KW, Hou HY, Shu CM. Thermal phenomena studies for dicumyl peroxide at various concentrations by DSC. Journal of Thermal Analysis and Calorimetry. 2006;83(1):41–44. doi:10.1007/s10973-005-6983-2.
3. Center for Chemical Process Safety, 1998, Guidelines for Pressure Relief and Effluent Handling Systems, American Institute of Chemical Engineers
4. Round robin vent sizing exercise on a gassy system: 40% dicumyl peroxide in butyrate solvent. Health and Safety Laboratory ; INERIS Collaboration, 2011. (s)
5. Luc Véchot, Jake Kay, Jill Wilday, Douglas Carson Jean-Pierre Bigot, Runaway reaction of non-tempered chemical systems: Development of a similarity vent-sizing tool at laboratory scale, Journal of Loss Prevention in the Process Industries, Volume 21, Issue 4, July 2008, Pages 359-366, ISSN 0950-4230, http://dx.doi.org/10.1016/j.jlp.2008.01.005