Novel Annular Jet Vortex Reactor for High-Temperature Thermochemical Conversion of Hydrocarbons to Acetylene

• Published in: ACS Engineering Au Vol. 2; no. 5; pp. 406 - 420
• Main Authors: Pannala, Sreekanth, Shtern, Vladimir, Chen, Lei, West, David
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.10.2022
• Subjects: streamlined design; annular conical jet; internal recirculation; pyrolysis; thermochemical conversion; combustion; tangential inlets; scalable reactor; wall protection
• ISSN: 2694-2488; 2694-2488
• DOI: 10.1021/acsengineeringau.2c00009

This paper describes a novel reactor for acetylene synthesis by high-temperature thermochemical conversion of paraffin hydrocarbons. The reactor utilizes a conical annular swirling jet, which becomes extremely thin as swirl intensifies. The small thickness provides fast mass, momentum, and heat transfer to facilitate the rapid heating and conversion of the reactants. We employ a unique wall shape for the converging–diverging combustion zone, which maintains relatively low reactor wall temperature and avoids the need for external cooling. The wall shape and angle were derived from an approximate analytical solution of the Navier–Stokes and energy equations, which leads to the maximal jet flow rate and avoids wall separation under extreme high swirling flow conditions. The analytical solution predicts a high-speed swirling flow, which includes a thin annular conical diverging jet where mass, momentum, and heat fluxes concentrate, and chemical reactions can occur rapidly. Across the jet, the temperature sharply drops from its large near-axis value to its small near-wall value. We illustrate and study these features with the help of numerical simulations of the Navier–Stokes, energy, and species equations and proof-of-concept experiments. The experiments confirm the thin annular conical shape of the flame, which is blue, transparent, and well anchored near the throat. The present device produces a flow pattern, which minimizes the reactor wall temperature, while producing light olefins with high selectivity and conversion.