Parimi, Sreekar (2010-12). Study of Methane Reforming in Warm Non-Equilibrium Plasma Discharges. Master's Thesis. Thesis uri icon

abstract

  • Utilization of natural gas in remote locations necessitates on-site conversion of methane into liquid fuels or high value products. The first step in forming high value products is the production of ethylene and acetylene. Non-thermal plasmas, due to their unique nonequilibrium characteristics, offer advantages over traditional methods of methane reforming. Different kinds of non-thermal plasmas are being investigated for methane reforming. Parameters of these processes like flow rate, discharge size, temperature and other variables determine efficiency of conversion. An efficient process is identified by a high yield and low specific energy of production for the desired product. A study of previous work reveals that higher energy density systems are more efficient for methane conversion to higher hydrocarbons as compared to low energy density systems. Some of the best results were found to be in the regime of warm discharges. Thermal equilibrium studies indicate that higher yields of ethylene are possible with an optimal control of reaction kinetics and fast quenching. With this idea, two different glow discharge reactor systems are designed and constructed for investigation of methane reforming. A counter flow micro plasma discharge system was used to investigate the trends of methane reforming products and the control parameters were optimized to get best possible ethylene yields while minimizing its specific energy. Later a magnetic glow discharge system is used and better results are obtained. Energy costs lower than thermal equilibrium calculations were achieved with magnetic glow discharge systems for both ethylene and acetylene. Yields are obtained from measurements of product concentrations using gas chromatography and power measurements are done using oscilloscope. Energy balance and mass balances are performed for product measurement accuracy and carbon deposition calculations. Carbon deposition is minimized through control of the temperature and residence time conditions in magnetic glow discharges. Ethylene production is observed to have lower specific energies at higher powers and lower flow rates in both reactors. An ethylene selectivity of 40 percent is achieved at an energy cost of 458MJ/Kg and an input energy cost of 5 MJ/Kg of methane.
  • Utilization of natural gas in remote locations necessitates on-site conversion of methane
    into liquid fuels or high value products. The first step in forming high value products is
    the production of ethylene and acetylene. Non-thermal plasmas, due to their unique nonequilibrium
    characteristics, offer advantages over traditional methods of methane
    reforming.
    Different kinds of non-thermal plasmas are being investigated for methane reforming.
    Parameters of these processes like flow rate, discharge size, temperature and other
    variables determine efficiency of conversion. An efficient process is identified by a high
    yield and low specific energy of production for the desired product. A study of previous
    work reveals that higher energy density systems are more efficient for methane
    conversion to higher hydrocarbons as compared to low energy density systems. Some of
    the best results were found to be in the regime of warm discharges. Thermal equilibrium
    studies indicate that higher yields of ethylene are possible with an optimal control of
    reaction kinetics and fast quenching. With this idea, two different glow discharge reactor
    systems are designed and constructed for investigation of methane reforming. A counter flow micro plasma discharge system was used to investigate the trends of methane
    reforming products and the control parameters were optimized to get best possible
    ethylene yields while minimizing its specific energy. Later a magnetic glow discharge
    system is used and better results are obtained. Energy costs lower than thermal
    equilibrium calculations were achieved with magnetic glow discharge systems for both
    ethylene and acetylene. Yields are obtained from measurements of product
    concentrations using gas chromatography and power measurements are done using
    oscilloscope. Energy balance and mass balances are performed for product measurement
    accuracy and carbon deposition calculations. Carbon deposition is minimized through
    control of the temperature and residence time conditions in magnetic glow discharges.
    Ethylene production is observed to have lower specific energies at higher powers and
    lower flow rates in both reactors. An ethylene selectivity of 40 percent is achieved at an
    energy cost of 458MJ/Kg and an input energy cost of 5 MJ/Kg of methane.

publication date

  • December 2010