石炭チャーのガス化反応速度に対する炭種の効果 スチームガス化反応

Abstract

Steam gasification of 13 kinds of coal char was carried out at temperatures of 1073-1273K and under total pressures of 0.4-1.6MPa by a high pressure tubular cell reactor. The surface area and the carbon structure of the reaction residue were determined at various char conversions up to about 0.90.The main component in the product gas was hydrogen, which amounted to about 50-60% of the total product gas for each char employed. The sum of CO and CO2 were nearly 40-50%. The ratio of CO to CO2 varied with the coal rank. The rate of CO2 formation was larger for the lower rank coals, whereas that of CO formation was larger for the higher rank coals. For each char, contribution of CO shift reaction to carbon-steam reaction, evaluated the mole ratio of H2 formation to (CO+CO2) formation, varied with the carbon conversion.The surface area of the reaction residue increased rapidly at the early stage of the reaction and then decreased after showing a maximum. The maximum values depended upon the kind of coal char. The surface area was found to be independent of the total pressure or of the reaction temperature at a certain conversion level.The instantaneous rate based on the unit surface area was very small at the initial and the final stages of the reaction. The (002) peak due to graphite structure, which had been detected for gasification by CO2 and H2, was seen in the X-ray diffraction spectra for reaction residues in the present experiment. The formation of graphite structure corresponded to the decrease of instantaneous rate at the final stage of the reaction.