Ignition, self-heating, and the effects of added gases during the thermal decomposition of di-t-butyl peroxide

✍ Scribed by John F. Griffiths; Jeremy R. Mullins

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 922 KB
• Volume: 56
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(84)90033-6

✦ Synopsis

The thermal decomposition of di-tertiary-butyl peroxide vapor is exothermic, and, in a closed vessel, the resultant self-heating may lead to ignition. The parameters that determine the criteria for ignition are encapsulated in Frank-Kamenetskii's 6, and they include exothetrnicity and Arrhenius constants, reactant pressure and its thermal conductivity, and vessel temperature and its size and shape. By varying the composition and proportions of diluting gases we focus attention here on the effect on criticality of changes in exothermicity and thermal conductivity.

Di-tertiary-butyl peroxide diluted with a range of diatomic gases (H2, N2, 0.99N 2 + 0.0102, 02) was decomposed in a spherical vessel ( ~ 1 dm 3 ) at total pressures less than I 0 Tort and vessel temperatures in the range 450-500K. Pressure changes and central temperature excesses were measured in different diluting gases under subcritical conditions, and the p--T a ignition boundaries were located. Overall stoichiometries, rate constants, activation energies, and concentration dependences have also been assessed. The thermal conductivities of some binary gas mixtures have been determined.

Ignition is brought about most easily in the presence of oxygen, and its effect is consistent with an augmentation of the exothermicity of reaction due to a change in stoichiometry. There is no degenerate chain branching. Nitrogen and hydrogen each enhance the thermal conductivity and make explosion more difficult to achieve. Quantitative comparisons are made here between/t cr (experimental) and predicted values for 6cr corrected for the effect of fuel consumption and the effect of variable thermal conductivity. Exothermicity and its role in determining conditions for ignition is then discussed. Finally, we show that modifications of the (p--T a) ignition limit due to increases in thermal conductivity can he predicted, thought present theories are inclined to give an underestimate of the change.