| 摘要 |
<p>The detrimental effects of polynuclear aromatic (PNA) by-products are controlled in a catalytic hydrocracking process by (a) introducing a reduced crude into a vacuum fractionation zone to produce a vacuum gas oil stream having a tendency to form detrimental PNA compounds in a hydrocracking zone, a slop wax side stream, and a vacuum bottoms; (b) contacting the vacuum gas oil stream in a hydrocracking zone with added hydrogen and a metal-promoted hydrocracking catalyst at elevated temperature and pressure sufficient to gain a substantial conversion to lower boiling products and to form trace quantities of PNA; (c) partially condensing the hydrocarbon effluent from the hydrocracking zone and separating the same into a low boiling hydrocarbon product stream and a stream containing unconverted hydrocarbons boiling above 650 DEG F (343 DEG C) and trace quantities of PNA compounds; and (d) introducing at least a portion of the stream containing the unconverted hydrocarbons and PNA compounds into the vacuum fractionation zone, thereby recovering a substantial portion of the polynuclear aromatic compounds in the slop wax side stream which significantly minimizes the introduction of the detrimental PNA compounds into the hydrocracking zone.</p> |
