Coal gasification in steam and air medium under plasma conditions: a preliminary study

The gasification of coal under steam and air plasma conditions at atmospheric pressure was investigated in a tube-type setup with an aim of producing synthesis gas. The plasma was diagnosed by optical emission spectroscopy (OES) and the synthesis gas was analyzed by gas chromatography (GC). It has been found that the content of H2 and CO in gas increases with increasing the arc input power, and passes through a maximum with the increase of current in electromagnetic coil. This is also the case for the variation trend of CO content in gas with the increase of the feeding rate of coal, but the H2 content in gas decreases as the feeding rate of coal increases. Under the experimental conditions tested, the content of H2+CO in the gas could reach 75% in volume with CO2 being less than 3.0 vol.%. The OES diagnosis reveals that CO+ ion and CH radical are present in the plasma and the variation trend of their intensities is, to some degree, in accordance with the variation trend of CO content in the gas, indicating that the CO+ ion and CH radical are the precursors or origins of CO species in the gas. The preliminary results presented here demonstrate that the gasification of coal under steam and air plasma conditions might become a new approach for production of synthesis gas.