Effect of solvent hydrotreatment on product yield in the coal liquefactionprocess

Effects of solvent hydrotreatment on product yields in the NEDOL coal lique faction process were examined based on the data obtained by a 150 t/d pilot plant operation. When the hydrogen gas consumption in the liquefaction sta ge was kept constant at 4.7 wt.%-daf(wt.% on the basis of dry and ash-free coal), the yield of the oil fraction increased from 51.0 to 54.9 wt.%-daf w ith an increase in the hydrogen gas consumption from 0.7 to 1.3 wt.%-daf in the hydrotreatment stage. In the hydrotreatment stage, about 30% of the hydrogen consumed was utilize d for enrichment of naphthenic hydrogen content in the solvent, and the res t was used for both the removal of nitrogen from the solvent and the produc tion of the light oil fraction. In the liquefaction stage, the hydrogen don ated from the solvent was more efficiently utilized than the gaseous hydrog en for the production of the oil fraction. Under the conditions that the to tal hydrogen consumption in the hydrotreatment and liquefaction stages was kept constant, the yield of oil fraction and the nitrogen content in oil fr action were higher when the hydrogen consumption in the liquefaction stage increased with concomitant decrease in the hydrotreatment stage. (C) 2000 E lsevier Science B.V. All rights reserved.