Institut Francais Du Pe'trole

Jean-Michel Toussaint

Gerard Paul Hotier

Daniel Lonchamp

Gabriel Terneuil

Choua Cohen

Nicolas Couenne

In a simulated mobile bed separation process, perturbations are corrected in the compositions of an extract (EA) or raffinate (RB) due to the dead volume introduced by at least one recycling pump (P) or compressor for a liquid, supercritical or gaseous mixture in a closed circuit of columns. The process is characterized in that each time an extract extraction stream (EA) or that of the raffinate (RB) passes from a position immediately anterior to a position immediately posterior to each of the dead volumes in the circuit, the flow rate of the flow rate regulated recycling pump or compressor is increased for the time which the extract or raffinate remains in the position immediately posterior to the dead volume When the extract or raffinate extraction stream passes from the immediately posterior position to the dead volume to the following position, the flow rate of the recycling pump or compressor is reduced so that the flow rate regains the value which would have been applied if the dead volume had been ignored. The invention is applicable to the separation of aromatic hydrocarbons containing 8 carbon atoms.

Chromatographic simulated mobile bed separation process with dead volume

A process and a device are described for the continuous separation, in the fluid phase, of a mixture of at least three constituents into three fractions. A so-called simulated countercurrent technique is used in a separation column packed with a sorbent having five zones 6, 5, 4, 3 and 2 with different functions, and the following sequence of steps is performed: so-called strong solvent S.sub.2 is introduced, a strong solvent extract E.sub.2 is removed, the same solvent is introduced but at a lower temperature and/or at a lower pressure (so-called weak solven S.sub.1), weak solvent extract E.sub.1 is drawn off, the mixture to be separated is introduced, weak solvent raffinate R is drawn off and a stream Roy is recycled alternately to the feed for strong solvent S.sub.2 and then to the feed for weak solvent S.sub.1. A stream coming from zone 6 is sent alternately to an outlet for storng solvent extract E.sub.2 and then to the inlet of the fifth zone. The various feeds and draw-offs are periodically caused to advance synchronously through the column. Application especially to the separation of glucose, xylose and arabinose and to the purification of water containing phenol, paracresol and toluene.

Continuous process and device for the chromatographic separation of a

A description is given of a process and an apparatus for continuous separation in fluid phase of a mixture of at least three constituents into three fractions. A technique is used, known as the simulated countercurrent technique, in a separation column which is filled with sorbent and has 6 zones 6, 5, 4, 3, 2 and 1 which have different functions, and the following sequence of steps is carried out: strong solvent S.sub.2 is introduced, an extract E.sub.2 with strong solvent is removed, weak solvent S.sub.1 is introduced. The extract with weak solvent E.sub.1 is drawn off, the separating mixture is introduced, refined substance is drawn off with weak solvent R, rinsing solvent (S.sub.1) is introduced, a current Rcy is recycled alternatingly towards the feed of strong solvent S.sub.2 and then towards the feed of weak solvent S.sub.1. A current coming from zone 6 is sent alternatingly to an outlet for the extract with strong solvent E.sub.2, then towards the intake of the fifth zone. The various feeds and substances removed are periodically advanced synchronously through the column. Application in particular for the separation of glucose, xylose and arabinose and for the separation of paraxylene, orthoxylene and metaxylene and ethyl benzene.

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Asnieres, France

Jean-Michel Toussaint