(449a) Reactive Mixing of Hydrocarbons and Water At Near-Critical Or Supercritical Conditions

The 1-D reactive mixing of an n-hexadecane droplet doped with a small fraction of hexyl sulfide in a pool of finite volume of supercritical water (SCW) is modeled. First, low temperature non-reactive cases are considered to study the phase separation behavior between hydrocarbons and water. Next, the temperatures are selected such that no phase separation is expected. Hexadecane and hexyl sulfide cracking, and coking are approximated using overall one-step chemical kinetics. This simplified reaction network provides, at least qualitatively, accurate prediction when compared with experimental results. Thermodynamics and transport sub-models are used to estimate the relevant physical properties. The current study provides microscale information, such as the coupling of mixing and chemical reaction processes, and insight into large scale mixing and reactions, such as how the system can be optimized by adjusting the temperature and water-to-hydrocarbon mass ratio, for various supercritical water applications. By considering reactions of hydrocarbon cracking, desulfurization, and coking, the current model is most relevant to the application of oil upgrading and desulfurization in supercritical water.