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A Film Boiling Study of Ethanol Pyrolysis

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posted on 04.05.2018, 00:00 authored by C. Thomas Avedisian, Wei-Chih Kuo, Wing Tsang, Adam Lowery
This paper reports a study of ethanol pyrolysis (C2H5OH, EtOH) by film boiling at temperatures ranging from 600 to 1500 K. The reactor space is created in a self-assembled manner by first bringing EtOH to a boil on the surface of a horizontal tube submerged in a pool of EtOH and then increasing the power to the tube in steps to force transitioning the boiling regimes through nucleate boiling, the critical heat flux state, and finally film boiling. EtOH pyrolysis is found to yield hydrogen in the highest concentration followed by ethylene (C2H4), methane (CH4), and carbon monoxide (CO) in approximately equal proportions. Ethane (C2H6) and carbon dioxide (CO) concentrations were several orders of magnitude lower. The abundance of hydrogen was conjectured to be due to the absence of chemical inhibitors in the system. Reactions to explain formation of the product gases are suggested based on the chain nature of EtOH decomposition. Liquid sampling showed the presence of refluxed water along with acetaldehyde (CH3CHO) and trace quantities of formaldehyde (CH2O) and ethyl acetate (CH3COOC2H5). Evidence of heterogeneous surface reactions is postulated for tube temperatures below about 1000 K. The results are consistent with more conventional reactor designs, which establishes the potential for film boiling to serve as a simple and useful chemical processing technology.