Plasma-assisted in-situ reforming of flare gases to achieve near-zero methane emissions

Project summary:

The objective of this project is to develop a non-thermal, low-temperature plasma-assisted system for in-situ flare gas reforming, ignition, and flame stabilization for small-size (tip diameter 3-8 inches, flow rate ~100,000 SCF/day) unmanned pipe flares. This technology will improve flare destruction and removal efficiency to 99.5 percent. Non-thermal, nanosecond (~10 nanosecond duration) plasma discharges at high-repetition rates (10-100 kHz) substantially enhance fuel reactivity by producing highly energized electrons, active metastable species, and intermediate hydrocarbon species with higher chemical reactivity, enabling improved burn speed and reduced ignition delay. Plasma discharges in desiccated air produce highly reactive radicals (e.g., O, OH, etc.) and reactive species (e.g., ozone), while in gaseous fuel (e.g., methane) produces a variety of hydrocarbons like ethane, ethylene, acetylene, cyclopropane, propylene, hydrogen, etc. Hydrocarbons like ethylene, acetylene, and hydrogen are highly reactive compared to methane and natural gas, which enhance the overall mixture reactivity and dramatically increase flare efficiency. The same plasma system can also be utilized as a source of on-demand ignition in flares, eliminating the need for a continuously burning pilot that creates additional emissions. Low operating energy (plasma running on solar-powered battery) and cost, easy implementation, and minimal maintenance make the plasma system an ideal candidate for infrequently maintained pipe flares operating in remote sites. The proposed technology is estimated to eliminate 3.8-15.1 million metric tons of CO2 equivalent methane emissions (28-72 percent reduction of the existing emissions) per year from flare operation.