A Distillation-type Process for Thermal Decomposition of Complex Hydrocarbons by Film Boiling

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CBET-1336657PI-AvedisianThe conversion of condensed phase (liquid) organic chemicals to lighter fractions forms the basis of some chemical process industries. The current practice is to vaporize the reactant liquid separately and then transport the gases to the high temperature reaction environment. The overarching objective of this research is to develop the understanding of the thermo/chemical processes that governs operation of a unique chemical reactor concept which closely couples vaporization with decomposition in a reaction space that essentially builds itself. The concept involves establishing film boiling on a heated surface submerged in a pool of the reactant liquid. This heat transfer mode is developed when bubbles cannot transport energy away from a surface at a fast enough rate to avoid coalescence. A vapor film then forms on the surface which insulates it from the surrounding liquid. The resulting temperature drop across the vapor film can be more than a thousand degrees even though the liquid is comparatively cold. Such temperatures are more than sufficient for organic gases to decompose. The reaction occurs in the physical space of the vapor film that is controlled almost entirely by operational variables, most directly temperature of the surface on which film boiling is established. If surface temperature is lowered below the minimum film boiling temperature the reactor literally disappears. This aspect of self-assembly is unique among chemical reactor technologies. This research will investigate the versatility of film boiling to convert organic reactants that form condensable species which are soluble in the reactant liquid, and high boiling point liquids that can stress containment seals for the liquid pool. An all-glass distillation-type design for a reactor will be fabricated and applied to a range of chemicals with a progression of decomposition complexities, including a reactant liquid that will decompose only to noncondensable gases with a known reaction rate constant, a chemical that forms both noncondensable and condensable gases, a liquid hydrocarbon with many conversion steps, and a chemical that is prominent as a waste product in the biodiesel production process. The major outcome of the project will be a greater understanding of how film boiling promotes chemical reaction of organic gases with an experimental design that is applicable to a wide range of organic liquids. Success in this investigation will result in a fundamental understanding of the vaporization and heat transfer processes that govern a new chemical reactor technology based on film boiling for decomposing organic chemicals into more high-valued products. For example, there is currently a world-wide glut of glycerine due to its formation in the biodiesel production process that threatens the viability of the industry. The inherent portability and high gas temperatures of film boiling suggests its feasibility to convert pure glycerine to synthesis gas with potential to create a useful energy source from what is currently a waste product by a simple process that could make more efficient the production of biofuel from bio-based seed oil feedstocks.