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 effluent stream and a para-xylene-depleted effluent stream; (c) separating said para-xylene-rich effluent stream to produce a para-xylene-rich product stream having a higher para-xylene concentration than said para-xylene-rich effluent stream and a para-xylene-depleted raffinate stream; (d) isomerizing at least a portion of said para-xylene-depleted effluent stream and 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 effluent and said para-xylene-depleted raffinate streams; (e) 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 streams; (f) 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; (g) recycling at least a portion of at least one of said first isomerate stream and said C7− hydrocarbons-depleted isomerate stream to said separating step (a); and (h) recovering at least a portion of said para-xylene-rich product stream as said para-xylene-rich product.