DESIGN AND CHARACTERIZATION OF A 2-D PLASMA REACTOR FOR METHANE PYROLYSIS

Date

2024-11-29

Author

Öztürk, Hüseyin

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Hydrogen is a crucial reactant in the chemical industry, especially in petrol refining and ammonia production. Due to the significant CO2 emissions of conventional H2 production, new routes of synthesis are being explored with a clear focus on developing processes that are entirely CO2-free. One promising route is methane pyrolysis, which is based on cracking CH4 in an O2-free environment, leading to the synthesis of only hydrogen and carbon black, the latter being an important commodity material. An industrially proven method of conducting methane pyrolysis is through the use of plasmas as the reactive environment. Using plasmas for this reaction is attractive since the process is fully electrified and completely intermittent, with very rapid turn-on/off times. However, the design variations of plasma reactors for methane pyrolysis are very limited, and the application of chemical reaction engineering fundamentals to the design and operation of these reactors is currently absent in the literature. This study focuses on the design and characterization of a unique, 2-dimensional, gliding arc (GA) plasma reactor for conducting methane pyrolysis. The GA is a warm plasma, and it combines high-temperature thermal conversion with non-equilibrium electron-impact chemistry. The reactor geometry was confined in one direction such that nearly all of the gas put in contact with the arc, increasing flow utilization in the reactor. Improvements on the residence time distribution were made through this geometrical modification, and gliding arc formation was visually and electrically analyzed under DC excitation. Thermal characterization indicated that the thermal efficiency of the reactor can be made to be as high as 50%, meaning that half of the electrical energy was converted to heating gas, whereas the rest was dissipated into the ambient through the reactor body. Preliminary experiments with methane indicated that using smooth insulating materials in the reactor significantly decreases carbon deposition, and inherently high flow rates are expected to aid the gliding arc running the methane pyrolysis reaction for prolonged times. When using methane-argon mixtures, conversion was seen to be relatively low, approximately 10%, indicating that the gliding arc should run at very high power densities.

Subject Keywords

Methane pyrolysis, plasma reactor, gliding arc, chemical reaction engineering, heat transfer

URI

https://hdl.handle.net/11511/113013

Collections

Graduate School of Natural and Applied Sciences, Thesis