Institut Francais Du Pe'trole

Separex

Ifp Energies Nouvelles

Nicolas Couenne

Gerard Paul Hotier

Choua Cohen

Luc Wolff

Dominique Humeau

Yann Creff

Roger-Marc Nicoud

Jean-Marc Bader

Pascal Duchene

Jean-Michel Toussaint

Method of optimizing the operation of a unit intended for separation of the components of a feed (xylenes) by simulated countercurrent in hybrid operating mode. The method allows to minimize the solvent ratio and to maximize the capacity of the separation unit while keeping product specifications such as purity and yield constant. It has been verified that these two objectives cannot be reached simultaneously and it is recommended to operate with a minimum solvent ratio while guaranteeing a high capacity compatible with stable operation of the separation unit. These optimization objectives are reached while keeping good stability around the optimum point thus defined, by using a known operation control process such as the one described in patent EP-875,268 for example.

Method of optimizing the operation of a xylene separation unit using simulated countercurrent

Method for controlling with precision a permanent in-line process for separating constituents of a mixture in a simulated moving bed separation system from concentration and flow rate measurements. The system comprises a set of columns forming a closed loop comprising several zones between fluid injection and draw-off points. Control of the process (linear or nonlinear) is performed from a knowledge model and from a certain number of operating variables at a plurality of measuring points along the loop (concentrations and flow rates for example) and characteristic measurements of the fluids injected and drawn off. Ratios respectively indicative of the ratio, in each of the different zones, between the fluid flow rates and the simulated adsorbent material flow rates, are determined from actual values of controlled variables depending on the measured operating variables (purity of the constituents, system yield, etc.). Values to be given to the operating variables in order to bring or to bring back the controlled variables to predetermined set values are determined from these ratios. The method can be applied for stabilizing separation processes, notably for aromatic hydrocarbons, in the presence of notable feedstock flow rate or quality variations.

Method for controlling with precision a process for separating

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

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 column sections. The volume of the section immediately upstream of the dead volume is reduced by an appropriate value when said dead volume is located downstream of this section and upstream of the extraction streams of said section, or the volume of the section immediately downstream of the dead volume is reduced by an appropriate value when the dead volume is located downstream of the injection streams into said section and upstream of this section. The invention is applicable to the separation of isomers of aromatic hydrocarbons containing 8 carbon atoms.

Growing community of inventors

Lyons, France

Nicolas Couenne