100 samples of recycle solvent were obtained by continuous opera-tion (50 days) of 1 ton/day coal liquefaction plant at Kimitu. Acenaphthene and biphenyl derivatives in the recycle solvents were analyzed in detail by the technique of selective ion measurement of GC/MS. Because of the replacement of the initial solvent by coal-derived product during the continuous operation, the amounts of acenaphthenes (including hydrogenated derivatives) and biphenyls (including hydrogenated derivatives) in the recycle solvents decreased remarkably while the amounts of compounds substituted by methyl or ethyl groups increased. The difference of degree of hydrogenation before and after hydrotreating process of solvent was about 40%, 20% and 20% for acenaphthene, methylacenaphthenes and biphenyl, respectively, and any significant difference was not observed for methylbiphenyls. The hydrogenated derivatives of alkyl-substituted acenaphthenes and biphenyls with over two carbon atoms in the alkyl chains were not found in the solvent.
To improve the combustion stability at lower load for a specific low NOx burner, which enabled to reduce both NOx and unburned carbon extremely, an adjustment method to raise local concentration of coal particle was invented. Coal parti-cle was concentrated at outside of primary air nozzle by using centrifugal force and coal concentration was controlled by a ring. At the outlet of nozzle, the swirl of primary air was prevented by straightener, because this swirl disturbed the forming of the reduction flame for NOx decomposition. So, the influence of straightener length and number on re-ducing the swirl was examined by cold flow test with a primary air nozzle model. Secondary, the coal concentrating effects in changing the ring position was investigated with a nozzle of combustion test burner. Finally, the combustion stability at low load was tested with the coal combustion test furnace. The swirl at the outlet decreased with the increase of the coefficient of straightener, which was defined by the ratio of the gross area of straightener to the cross section area of primary air nozzle. The swirl number was decreased to zero when the straightener coefficient is greater than 1.2. The ring placed close to the outlet concentrated coal particle most efficiently and the local pulverized coal concentration rose 1.5 times as high as the mean coal concentration in primary air. With this arrangement, the combus-tion state at lower load became stable and the minimum load was improved to 20% as same as an oil burner. At lower load, the coal concentrating was very effective to re-duce the unburned carbon with little increase of the NOx emission. On the other hand, the coal concentration was excessive when the ring was close to the outlet at higher load. So, the ring was placed far from the outlet and the coal concentrating was modified so that the emission characteristics of NOx and unburned carbon in fly ash of the burner with coal concentration adjustment was the same as the characteristics of the burner without these instruments.
The hexane insoluble-chloroform soluble (HI-CFS) fractions which were obtained by the secondary pyrolysis of coal tar in a flow reactor at 700-900°C for 5-22 s were characterized by estimating the probable structure of the HI-CFS fraction and the concentrations of the functional groups on the basis of 1H-NMR and elemental analysis data using a computer. The structural pat-tern of coal tar was divided into the functional groups, i, e., condensed aromatics with one-ring to eight-ring, alkyl chain, methylene bridge, and hydroxyl and hydroaromatic group.After secon-dary pyrolysis of coal tar, the distribution of condensed aromatics which consisted in molecules in HI-CFS shifted to the big ring number side with an elapse of time and a rise in reaction temperature. However, the distribution of condensed aromatics in HI-CFS fraction of raw coal tar was from two-ring to six-ring, those of pyrolyzed coal tar changed from three-ring to seven-ring at 800 and 900°C. The maximum in the distribution of condensed aromatics changed from four-ring to five-ring at 800 and 900°C. Further, the changes in the concentrations of functional groups such as aliphatic chains, hydroxyl group and methylene bridge showed that these functional groups de-composed at initial stage of secondary pyrolysis.
In order to convert cellulosic biomass to raw materials for alcohol fermentation, cellulose and a chinquapin, a hard wood, were hydrothermolyzed with hot compressed water in a batch reactor at temperatures between 250 and 405°C. Cellulose was quickly solubilized to water, and nearly 40% of cellulose could be sac-charified to hexose by adjusting the heating time in the range of 13-30s at the heating temperature of 305-405°C. As a result of fermentation test of the water soluble frac-tion, the fermentation rate was found to be remarkably improved by removing furfurals in the solution through an active carbon treatment, and further, good mass balance was confirmed between the consumed hexose and formed ethanol. In the case of chinquapin, the hydrothermolysis started at lower temperature than pure cellulse. Active lignin was first decomposed, and then hemicellulose followed by cellulose was hydrolyzed to water solubles (WS), although stable lignin was hard to de-compose and remained as solid residue (methanol insolubles, MI). An increase in the heating temperature caused the decrease in the yield of MI, but did not the increase in the yield of WS because of the second decomposition of WS. However, the WS includ-ing over 20% of hexose was obtained in the yield of near 30% by optimizing the heating time. Since species from lignin were obtained as methanol solubles separately from WS, the WS were suitable for the fermentation and ethanol was successfully produced with saccharomyces.