Patent ID: 9731220
Date: 2017-08-15
CPC Classifications: B01D,C07C

Claim:
1. A process for simulated counter-current separation of xylenes comprising a first adsorption step using two adsorbers each containing twelve beds, each of the adsorbers having a line for introducing feed (F), a line for introducing eluent (D), a line for withdrawing extract (E) and a line for withdrawing raffinate (R) and being divided into 4 chromatographic zones defined as follows: zone 1: para-xylene desorption zone, included between the injection of desorbant D and the removal of extract E; zone 2: isomers of para-xylene desorption zone, included between the removal of the extract E and the injection of the feed to be fractionated F; zone 3: para-xylene adsorption zone, included between the injection of the feed and the withdrawal of the raffinate R; zone 4: zone located between the withdrawal of the raffinate R and the injection of the desorbant; and the two adsorbers functioning in parallel, i.e. the twelfth bed of the first adsorber (a) is connected to the first bed of said adsorber via a line containing a recirculation pump, and the twelfth bed of the second adsorber is connected to the first bed of said second adsorber via a line containing a recirculation pump which is distinct from the preceding pump; the process further comprising: a step for distilling a mixture of the two raffinates in a single distillation column from which a mixture of xylenes depleted in para-xylene is withdrawn overhead and the desorbant, which is recycled, is withdrawn from the bottom; a step for distilling the two extracts in one or two distillation column(s) from which substantially pure para-xylene with a purity of more than 99.7% by weight is withdrawn overhead and the desorbant is withdrawn from the bottom and recycled.