ARTICLE IN PRESS JID: PROCI [m;June 28, 2018;9:14] Available online at www.sciencedirect.com Proceedings of the Combustion Institute 000 (2018) 1–8 www.elsevier.com/locate/proci Experimental and numerical study of a two-stage natural gas combustion pyrolysis reactor for acetylene production: The role of delayed mixing Lei Chen ∗ , Sreekanth Pannala , Balamurali Nair , Istvan Lengyel , Byeongjin Baek, Chunliang Wu, Retheesh VM, David West SABIC Global Corporate Research, 14100 Southwest Freeway Suite 600, Sugar Land, TX 77479, USA Received 30 November 2017; accepted 28 May 2018 Available online xxx Abstract Combustion pyrolysis of natural gas is a promising process for high value-added chemicals such as alkynes and olefns. This work introduces recent experimental and computational studies of a 2.5 kTA (thousand metric ton per year) two-stage combustion pyrolysis unit, and focuses on the role of mixing on pyrolysis. Temperature, pressure, and gas composition measurements were experimentally obtained at different mixer and pyrolysis reactor lengths. Kinetic studies indicate that fast mixing of the hot combustion gas and crack- ing natural gas streams to the optimum temperature window of about 2000 K promotes C 2+ formation and minimizes partial oxidation. Computational Fluid Dynamics (CFD) reacting turbulent fow simulations us- ing Reynolds Average Navier–Stokes (RANS) and Large Eddy Simulation (LES) approaches with a detailed reaction mechanism were conducted on the integrated reactor system including combustor, mixer, and py- rolysis reactor. Results show good agreement between the CFD simulation results and experimental data, and reveal that the overall C 2+ yield decreases to ∼21% due to the delayed mixing, compared to ∼36% in the perfect mixing scenario. Detailed comparison between experimental and simulation results are discussed, and potential strategies for reactor design and performance improvements are suggested. © 2018 Published by Elsevier Inc. on behalf of The Combustion Institute. Keywords: Combustion pyrolysis; Methane; Acetylene; Kinetics; CFD 1. Introduction The growing abundance of natural gas resources from the shale gas revolution and their poten- tial competitive cost advantage with respect to ∗ Corresponding author. E-mail address: lei.chen@sabic.com (L. Chen). other light paraffnic hydrocarbons make the pro- duction of chemical intermediates and other high value chemicals from natural gas an attractive op- tion. There are numerous methods of converting methane to higher molecular weight olefns and alkynes, and the most prevalent methods involve oxidative coupling, partial oxidation, or pyrolysis. Of all these approaches, high temperature pyrolysis of methane for production of acetylene is promis- https://doi.org/10.1016/j.proci.2018.05.170 1540-7489 © 2018 Published by Elsevier Inc. on behalf of The Combustion Institute. Please cite this article as: L. Chen et al., Experimental and numerical study of a two-stage natural gas combustion pyrolysis reactor for acetylene production: The role of delayed mixing, Proceedings of the Combustion Institute (2018), https://doi.org/10.1016/j.proci.2018.05.170