Low NOx combustion technologies for gas turbines, such as lean premixedflame combustion, have been developed and used for commercial gas turbines to meet stringent NOx regulations. However, lower NOx is required for themore severe regulations in some areas. For developing a practical catalytic combustor, intensive studies have been carried out for the screening of a favourable catalyst, the optimization of monolith sizes, the research of pressureeffects on performances and the confirmation of the effectiveness of a catalytic pilot flame. With these results, an ultra low NOx combustor for a gas turbine, which is based on a catalytic pilot flame and a lean premixed main flame, has been developed and achieved NOx of less than 10 ppm on high pressure combustion tests. High temperature gas, produced by catalytic combustion, is used as a pilot for flame holding of premixed main flames. This manner of combustion has some advantages compared with previous combustion technologies. These advantages are, besides less NOx from catalytic pilot than from diffusion flame pilot, less pressure drop on the setting catalytic pilot in parallel with main flames and high reliability by using smaller catalyst. The catalyst endurance tests are now under being carried out for the practical applications of this ultra low NOx combustor for gas turbines.
In order to specify the effect of the Mo catalyst on the coal liquefaction, we experimented on the coal liquefaction using different types of Mo catalyst: Co-Mo/Al2O3 catalyst in two different shapes of the same composition, i. e., (a) extrusion and (b) powder: oil soluble Mo in two different types, i. e., (c) in the case of dissolving in the solvent and (d) in the case of impregnating in the coal in advance. When we used the hydrogenated anthracene oil (HAO) as a solvent at 673 K and 723 K, we did not find the effect of the shapes of (a) and (b) and type of (c) and (d). In the case of anthracene oil (AO), the conversion is higher in the case of (b) compared with in the case of (a). The differences is effected by limitation of the diffusion of the reactant in the poreof Co-Mo/Al2O3 catalyst. We expected the increase of the conversion in the case of (d) by the direct catalysis of hydrogenation of solid coal. However, therewas a little or negative effect on the reaction because of the dissolving anddispersing process of Mo metal to the solvent. The relationship between H2 consumption and coal conversion to hexane solubles: Xh was clearly divided in groups according to solvent species not concerning with the kinds of the catalyst.We concluded by comparing the results of AO and HAO that hydrogen donor capacity of HAO is 6 mol-H2/kg.