A Nonpremixed Annular Jet Vortex Chamber Reactor for Methane Pyrolysis under Oxygen-Enriched Conditions

Abstract

A novel high-swirl reactor ANJEVOC-CP (annular jet vortex chamber for combustion pyrolysis) was designed for producing high-value chemicals such as alkynes and olefins from natural gas. In such a single-stage nonpremixed combustion pyrolysis process, methane and oxygen streams are spirally conveyed into the ANJEVOC-CP burner creating high-swirl annular jets around an internal recirculation zone, leading to a compact nonpremixed fuel-rich flame for methane pyrolysis. Computational fluid dynamics (CFD) simulations of this reactor concept indicate the potential for high alkyne yield due to the rapid mixing of combustion products with CH4 under a broad range of operating conditions; and this was experimentally verified in a lab-scale reactor under a subset of conditions (enriched oxygen concentration from 21% to 60% by volume and equivalence ratio from 1.28 to 2.4). The experimental studies showed 10.4 mol % carbon-based overall acetylene yield with up to 60% enriched oxygen molar concentration in the oxidizer stream in the lab-scale experiment. The CFD simulation predictions of the fluid flow and reactor performance are in reasonable agreement with the experimental observations and provided complementary insights into the respective roles of high swirl, species and thermal transport, and reaction kinetics that contribute to the high performance. Using a reduced GRI-Mech 3.0 and a modified GRI mechanism, the model predicted 20–25% overall acetylene yield at the same scale with higher enriched oxygen concentration. Considering the fact that excessive heat loss due to the high surface-area-to-volume ratio in the small lab-scale prototype with inert gas dilution could degrade performance, ANJEVOC-CP is a promising methane conversion technology for acetylene production and deserves further investigation at larger scales.

Chemisorption of CO2 in a gas–liquid vortex reactor: An interphase mass transfer efficiency assessment

“…The balance between the radially inward gas drag force and radially outward centrifugal force holds a certain amount of liquid near the outer edge of the vortex chamber, constantly refreshing the liquid into a dynamic equilibrium state and generating a large gas–liquid interfacial area 21 . It is worth mentioning that previous studies mainly focused on the vortex reactor used in gas–solid systems 23–34 . Successful experience has led to the exploration of gas–liquid systems in the reactor, and more specifically of CO 2 capture in this study.…”

“…21 It is worth mentioning that previous studies mainly focused on the vortex reactor used in gas-solid systems. [23][24][25][26][27][28][29][30][31][32][33][34] Successful experience has led to the exploration of gas-liquid systems in the reactor, and more specifically of CO 2 capture in this study.…”

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

“…To verify the theoretical derivation above, CFD simulations were conducted with the ANJEVOC-CP reactor geometry at a small scale. The CFD model has been developed for methane combustion pyrolysis applications and validated against the experimental data with the ANJEVOC reactor and another reactor discussed in our previous work. , ANSYS FLUENT 19.3 was used as the computing platform for the CFD modeling, with the Reynolds stress model for turbulent flow, the Eddy dissipation concept (EDC) model for turbulence–chemistry interaction, and a modified GRI-Mech 3.0 reaction mechanism for the detailed methane combustion and pyrolysis reactions. To reduce the computational cost of chemical kinetics calculation, all nitrogen species and related reactions were removed from the original GRI-Mech 3.0, leading to a total of 35 species and 217 reaction steps in the CFD simulations.…”

“…During the last decade, significant advances in the development of efficient vortex contactor units have been achieved by a group of researchers from Laboratory for Chemical Technology, Gent University. − Lab-to-pilot scale advanced reactors have been developed in the areas of single and multiphase flows. Complimentary to this research, our current study addresses gas–gas high-temperature flows where pure or enriched oxygen combustion and other chemical reactions occur.…”

“…The reactor design (Figure ) and the numerical results predicting the ANJEVOC flow pattern and distribution of temperature, pressure, and species concentration are the main new results of this paper. The experimental results, obtained in collaboration with Santosh Shanbhogue and Ahmed Ghoniem at Massachusetts Institute of Technology (MIT), validate our analytical and numerical predictions . In the rest of the paper, we explain theory behind swirling conical similar jets and our analytical solution explaining the temperature field in a vortex burner in Section , discuss combustion experiments demonstrating a thin annular blue flame in Section , report results of our numerical simulations in Section , and summarize the findings in Section .…”