| 摘要 |
A process for the dual riser contacting of a primary feed and a secondary recycle feed fraction uses independent recovery of the separate streams from the riser cracking zone to improve the product yields and properties. Separate recovery segregates the upgraded recracked components from the rest of the primary cracked products. The benefits of selective of recracking are lost if the upgraded products from the recycle stream become recombined with the primary cracked product. The selectively recovered recycle feed may undergo hydroprocessing to hydrogenate, hydrocrack and/or hydrotreatment before recracking. The process can also make highly efficient use of the high residual activity in the catalyst that has contacted the secondary feed.
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