Plasma reforming of methane

Thermal plasma technology can be used in the production of hydrogen and hydrogen-rich gases from a variety of fuels. This paper describes experiments and calculations of high-temperature conversion of methane using homogeneous and heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely high temperatures (several thousand degrees Celsius) and high degree of ionization. The high temperatures accelerate the reactions involved in the reforming process. Plasma reformers can be operated with a broad range of fuels, are very compact and are very light (because of high power density), have fast response time (fraction of a second), can be manufactured with minimal cost (they use simple metallic or carbon electrodes and simple power supplies), and have high conversion efficiencies. Hydrogen-rich gas (50-75% H-2, with 25-50% CO for steam reforming) can be efficiently made in compact plasma reformers. Experiments have been carried out in a small device (2-3 kW) and without the use of efficient heat regeneration. For partial oxidation it was determined that the specific energy consumption in the plasma reforming processes is 40 MJ/kg H-2 (without the energy consumption reduction that can be obtained from heat regeneration from an efficient heat exchanger). Larger plasmatrons, better reactor thermal insulation, efficient heat regeneration, and improved plasma catalysis could also play a major role in specific energy consumption reduction. With an appropriate heat exchanger to provide a high degree of heat regeneration, the projected specific energy consumption is expected to be similar to 15-20 MJ/kg H-2. In addition, a system has been demonstrated for hydrogen production with low CO content (similar to 2%) with power densities of similar to 10 kW (H-2 HHV)/L of reactor, or similar to 4 m(3)/h H-2 per liter of reactor. Power density should increase further with power and improved design.