(53c) Theoretical Evaluation of the Reactivity for Hydroxylamine System using a Kinetic Model Approach

Abstract: From 1980 to 2001 the U.S Chemical Safety and Hazard Investigation Board (CSB) reported 167 incidents involving reactive chemicals occurred in the U.S. According to the report 35% of these incidents where caused by thermal runaway reactions. The Hydroxylamine (HA) compound has been involved in two of these tragic accidents. Identification and understanding runaway reactions hazards help in preventing the recurrence of similar events. It is also essential to acquire knowledge of detailed chemical kinetics of energetic materials in order to optimize current processes.

Understanding the mechanisms of how a runaway reaction propagates help to identify conditions needed to control or mitigate these reactions. The aim of this research is to develop a robust computational methodology using the reactivity of the hydroxylamine as example to prevent the incident recurrence related to runaway reactions. Detailed kinetic model, i.e.,a series of elementary reactions for HA decomposition were developed. This model can be applied to ensure reliable scale-up of theoretical data to industrial simulations.

This study proposes a methodology consisting of three steps; first, computational predictions of the reaction mechanisms and calculation of thermodynamic properties of the reactions involved in the HA decomposition using GAUSSIAN. Second, the estimation of individual reaction rate constants. Variational Transition State Theory (VTST) using software as POLYRATE and GAUSSIAN is obtained from the literature where the application in this step consist in calculate the transition state and the activation energy where the reactions have occurred. Finally to study industrial scale operations, CFD simulations using ANSYS-FLUENT is performed in order to evaluate the behavior of the HA for an industrial process. From the obtained results, it is possible to estimate the accuracy of the proposed methodology to identify and quantify runaway reaction hazards.

Keywords: Runaway reactions, hydroxylamine, activation energy and industrial simulations.