PROCESS FOR MAKING XYLENE ISOMER USING A DEHEPTANIZER WITH A SIDE DRAW RECYCLE

摘要

In processes for recovering one or more xylene isomers and isomerizing the remaining isomers for recycle, the isomerate (118) is distilled to provide a toluene-containing overhead (122), a mid-boiling fraction containing C8 aromatics (124) and a bottoms fraction containing C8 aromatics and C9+ aromatics (126). The mid-boiling fraction (124) is recycled to the unit (110) for recovering the sought xylene isomers and has sufficiently low content of C9+ aromatics that the separation feed (108) to the unit for recovering the sought xylene isomers (110) contains up to 500 ppm-mass C9+ aromatics. The processes provide a high quality xylene isomer product while achieving at least one of debottlenecking, energy savings and capital savings.