Energy Efficient Processes for Xylenes Production

摘要

The invention is directed to a process to produce para-xylene and, optionally, ortho-xylene, including coupling two in-series xylenes separation systems with two parallel isomerization systems for energy savings and/or productivity increases.

主权项

1. A process for producing a para-xylene-rich product, the process comprising:
(a) separating a feedstock comprising C8+ aromatics to produce a C8 aromatics-rich stream and a C9+ aromatics-rich stream; (b) separating at least a portion of said C8 aromatics-rich stream to produce a para-xylene-rich product stream and a para-xylene-depleted raffinate stream; (c) isomerizing at least a portion of said para-xylene-depleted raffinate stream to produce a first isomerate stream having a higher para-xylene concentration than said para-xylene-depleted raffinate stream; (d) isomerizing at least another portion of said para-xylene-depleted raffinate stream to produce a second isomerate stream having a higher para-xylene concentration than said para-xylene-depleted raffinate stream; (e) separating C7-hydrocarbons from at least a portion of said second isomerate stream and optionally at least a portion of said first isomerate stream to produce a C7-hydrocarbons-rich stream and a C7-hydrocarbons-depleted isomerate stream having a lower C7-hydrocarbons concentration than said second and optionally said first isomerate streams; (f) separating at least a portion of said first isomerate stream and optionally at least a portion of said C7-hydrocarbons-depleted isomerate stream to produce a para-xylene-rich effluent stream and a para-xylene-depleted effluent stream; (g) supplying a least a portion of said para-xylene-depleted effluent stream to isomerizing step (c) and/or step (d); (h) recycling at least a portion of said para-xylene-rich effluent stream to separating step (a); and optionally separating step (b); and (i) recovering at least a portion of said para-xylene-rich product stream as said para-xylene-rich product.