Effects of slurry heating rate on conversion during short-contact-time coal liquefaction

The primary purpose of this project was to study short-contact-time coal liquefaction In tubing-bomb microreactors using a recycle solvent from the Lummus Integrated Two-Stage Liquefaction Process and a Kentucky No. 9 coal (without the addition of gaseous hydrogen). Experiments were conducted to relate product stability to process para meters, Including the time-temperature history of the slurry during heatup to reaction temperature and the time which the slurry remained at temperature in the reactor.

The most Important result of this study was the significant Increases In conversion to pyridine-soluble material obtained by modifying the portion of the slurry heating curve corresponding to the preheater portion of the process. As measured by pyridine-soluble com ponents, the yields from reactions at 700 K (800°F) at 5-mln residence time at reaction temperature Increased from 71 wt % (dry mineral matter-free coal) to 89 wt % by Introducing a 2.5-mln delay at 589 K (600°F) during heatup.

Other results Indicated that conversion Is significantly affected by the degree of mixing; an increase in pyridine insolubles was observed for reaction times greater than 10 min at a temperature of 733 K (860°F). The Lummus solvent used in the study appears to contain a significant fraction of polycyclic aromatics containing two to five aromatic rings.