PLASMA REFORMING OF METHANE

Thermal plasma technology can be used in the production of hydrogen an d hydrogen-rich gases from a variety of fuels. This paper describes ex periments and calculations of high-temperature conversion of methane u sing homogeneous and heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely hi gh 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 p ower density), have fast response time (fraction of a second), can be manufactured with minimal cost (they use simple metallic or carbon ele ctrodes and simple power supplies), and have high conversion efficienc ies. Hydrogen-rich gas (50-75% H-2, with 25-50% CO for steam reforming ) can be efficiently made in compact plasma reformers. Experiments hav e been carried out in a small device (2-3 kW) and without the use of e fficient heat regeneration. For partial oxidation it was determined th at the specific energy consumption in the plasma reforming processes i s 40 MJ/kg H-2 (without the energy consumption reduction that can be o btained from heat regeneration from an efficient heat exchanger). Larg er plasmatrons, better reactor thermal insulation, efficient heat rege neration, and improved plasma catalysis could also play a major role i n specific energy consumption reduction. With an appropriate heat exch anger to provide a high degree of heat regeneration, the projected spe cific energy consumption is expected to be similar to 15-20 MJ/kg H-2. In addition, a system has been demonstrated for hydrogen production w ith 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.