The Safe Storage Study for Autocatalytic Reactive Chemicals

In the U.S. Chemical Safety and Hazard Investigation Board (CSB) report, Improving Reactive Hazard Management, there are 37 out of 167 accidents, which occurred in a storage tank or a storage area. This fact demonstrates that thermal runaway problems in chemical storage processes have not been give enough attention. Hydroxylamine Nitrate (HAN) is an important member of the hydroxylamine compound family and its diluted aqueous solution is widely used in the nuclear industry for equipment decontamination. It is also used as a solid or aqueous propellant. Due to its instability and autocatalytic behavior, it has been involved in several incidents at the Hanford and Savannah River Sites (SRS). Much research has been conducted on HAN in different areas, such as combustion mechanism, decomposition mechanism, and runaway behavior. However, the autocatalytic behavior of HAN at runaway stage has not been fully addressed due to its highly exothermic and rapid decomposition behavior. This work focuses on extracting its autocatalytic kinetics mechanism and studying its critical behavior from adiabatic calorimetry measurements. The lumped autocatalytic kinetics model, the associated model parameters and HAN critical condition are determined for the first time. The contamination effect of iron ions and nitric acid on diluted hydroxylamine nitrate solution is also studied. This work also identified the safe storage conditions for a small quantity HAN diluted solution with thermal explosion theory. Computational Fluid Dynamics (CFD) was used to further study the influence of natural convection and system scale on the critical behavior for a large quantity of chemical and thus proposed the practical storage guidelines for industrial practice.