Advanced direct coal liquefaction. Quarterly technical progress report No. 2, December 1983-February 1984

Abstract

Five Bench-Scale coal liquefaction runs were completed with Wyoming subbituminous coal in a two-stage process scheme. In this process scheme, LDAR, the lighter fraction of ash-free resid, was fed to the catalytic stage prior to its recycle to the thermal stage, whereas DAR, the heavy fraction of the deashed resid, was directly recycled to the thermal stage without any intermediate processing step. The results indicate that increasing coal space rate in the dissolver resulted in lower coal conversion and reduced distillate yield in this process configuration. The coal conversions decreased from 92 wt% to 89 wt% (MAF coal) and the distillate yield was reduced from 50 wt% to less than 40 wt% (MAF coal), as the coal space velocity increased. Attempts to duplicate the yields of Run 32, at comparable process conditions in Runs 37 and 38, were unsuccessful. Several process parameters were investigated but failed to show why the yields of Run 32 could not be duplicated. Valuable process related information was gained as a result of process parameter studies completed during these runs. At comparable process conditions, coal conversions were lower by about 3 to 4 relative percent and were only in the 87 wt% (MAF coal) range.more » Similarly, the distillate yield was about 40 wt% (MAF coal) which is about 10 wt% lower than observed in Run 32. Although no exact cause for these results could be determined, it appeared that the H/C atomic ratio of the solvent and possibly the flow pattern (plug-flow versus back-mixed) could have affected the coal conversion and quantity of distillate product produced. A significant decrease in coal conversion of 4 to 5 wt% was observed when the disposable catalyst (iron oxide) was removed from the reaction mixture and therefore substantiates the need for a disposable catalyst in the liquefaction of Wyoming subbituminous coal.« less