Abstract: A fluid distributing-collecting process using a device for bringing fluids and solids into contact comprises several distributor plates and several panels for mixing, distributing or extracting fluids. The system for practicing the method includes at least one level one chamber in connection with the outside of said device with at least one hose and, at least one level two chamber that is linked with the level one chamber and that comprises one or more connecting hoses of a selected length that are arranged in at least one zone. The zone is identified relative to an angle &agr; relative to a radius of a plate and corresponds to a given angle sector, whereby hose lengths, angle &agr; and the angle sector are selected in accordance with the process so that injected fluid arrives approximately at the same time on all of the panels of the same plate. This process is used for separation of paraxylene in a simulated moving bed.

Abstract: A fluid distributing-collecting system for a device for bringing fluids and solids into contact comprising several distributor plates and several panels for mixing, distributing or extracting fluids. The system comprises at least one level 1 chamber in connection with the outside of said device with at least one hose and, at least one level 2 chamber that is linked with the level 1 chamber and that comprises one or more connecting hoses of a selected length that are arranged in at least one zone. The zone is identified relative to an angle .alpha. relative to a radius of a plate and corresponds to a given angle sector, whereby said hose lengths, angle .alpha. and the angle sector are selected so that the injected fluid arrives approximately at the same time on all of the panels of the same plate. This system is used for separation of paraxylene in a simulated moving bed.

Abstract: 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.).