Investigation of Thermal Hazards in Reaction Systems

Effective process safety programs provide for the prevention and control of hazards, which result in risk reduction and thus sustained value. A major source of hazards within the chemical process industries involves process scale up, as risks of thermal runaway and explosions are introduced. Thermal runaway occurs when the heat produced in a chemical reaction exceeds the heat removed, which results in an uncontrolled accelerating rate of reaction. An example of a process scale-up incident is the MFG Chemicals facility in Dalton, GA. For this incident, a reactor containing 4000 gallons of triallyl cyanurate overheated, resulting in an explosion that caused 154 injuries. Scale-up incidents such as these often result from a lack of understanding of the reactive chemistry hazards associated with the reaction being carried out as well as an ineffective process design and hazard review, which can result in insufficient heat removal capabilities.

In this research, the Mettler Toledo RC1 Calorimeter, an isothermal calorimeter, is used to investigate thermal hazards associated with reaction systems found within the process industries, particularly oxidation reactions. This provides useful data at the lab scale that can be used for safe process scale up as well as analysis of hazards to identify necessary layers of protection to be implemented. As oxidation reactions tend to be highly exothermic, thorough understanding of the reactive chemistry mechanisms is critical for scaling up the reactions for use in industrial settings.

For this work, the oxidation reactions of 2-butanol to 2-butanone and 2-pentanol to 2-pentanone, which are catalyzed by titanium silicalite-1, are investigated. For these, the reaction temperature, reactant quantity, and catalyst quantity are varied. The effects of these changes on the temperature profiles, heat release rates, and maximum adiabatic temperature increases are investigated. Based on these results, potential hazards are identified and methods for safely scaling up these reactions are proposed.