摘要:
A monochromatic light signal of a wavelength of between 400 and 1300 nanometers is simultaneously passed by a source 1, a beam splitter 2 and optical fibers 3, 3a to at least two points of a zone 9 for the separation of a mixture of isomers and aromatic hydrocarbons having from 8 to 10 carbons atoms. A polychromatic signal is recovered corresponding to the Raman effect between 400 and 3500 cm.sup.-1 by optical receiving fibers 5, 5a connected to sensors 4 at the locations of said points. The chemical composition of the mixture is determined from the Raman spectra obtained by a spectrometer 6. The analysis sequence is repeated, the profiles with respect to the concentration of the isomers in the mixture are reconstituted and by comparison with reference concentration profiles, action is taken on at least on operational variable 11, 12 of the separation process. Application of this process to the regulation of simulated mobile beds, a distillation operation or a crystallization process for obtaining paraxylene or orthoxylene are also provided.
摘要:
The present invention describes a method for measuring the concentrations of species present at one point of a separation unit functioning in simulated moving bed mode (SMB), using an immersing probe located at one point in the unit or on one of the streams entering or leaving said unit, and a thermocouple located in the vicinity of the immersing probe, in which a Raman spectrum obtained using a laser source functioning at a wavelength of 785 nm is utilized.
摘要:
A process for the combined production of para-xylene and benzene comprises: separating a first feed, by adsorption in a simulated moving bed SMB, to produce an extract E rich in para-xylene and at least one raffinate R which is depleted in para-xylene; converting a secondary feed of toluene by selective disproportionation to produce benzene and xylenes; a) at the start of the cycle, producing a supplemental quantity of para-xylene in a crystallization unit supplied with the xylenes from the disproportionation; b) at the end of the cycle, when the adsorbant has aged: dividing the distilled extract E into a first fraction Ea and a complementary second fraction Eb; replacing the feed to the initial crystallization by the stream Ea; and recycling the xylenes from the disproportionation to the SMB. The invention enables para-xylene and benzene production to be maintained despite ageing of the SMB absorbent.
摘要:
A simulated moving bed (SMB) separation device comprising a column, beds Ai of adsorbent separated by plates Pi with a single distribution and extraction network for fluids, in particular feed F, desorbant D, raffinate R and extract B, and a plurality of two-way valves for distribution of said fluids, said valves being limited in number compared with the prior art. The column is divided into a plurality of sectors Sk with 2 or 3 superimposed plates, each sector Sk comprising an external bypass line Lk connected to each plate Pi of Sk via a connector comprising a plate valve Vi. Each line Lk comprises a controlled means for limiting its internal flow, and is connected to each of the fluid networks F, D, R, E via a single line comprising a single controlled two-way isolation valve to supply for sequential supply or withdrawal of the corresponding fluid F, D, R or E towards or from the sector Sk under consideration. The SMB device may be used for the separation of para-xylene or meta-xylene from an aromatic C8 cut.
摘要:
A simulated moving bed flushing apparatus and its use are described. The adsorber comprises a plurality of beds (10, 11) of adsorbent, each bed being connected to a distribution means (5) comprising two fluid distribution lines (2,1,) the first distribution line (2) of each distribution means being connected to at least one inlet (7) for feed and to at least one raffmate outlet (8), the other line 1 being connected to at least one solvent inlet (3) and to at least one extract outlet (4), each inlet and outlet comprising an on-off valve (7a, 8a, 3a, 4a), the first distribution line (2) comprising a flushing valve (9), and all of the flushing valves (9) relating to all of the distribution lines (2) are connected to means (100, 102) for circulating a fluid to be displaced. FIG. 1 to be published.
摘要:
A process for separating paraxylene at very high purity from a charge of xylene isomers, comprising a selective adsorption of a fraction that is rich in paraxylene, at least one high-temperature crystallization of this fraction, and an isomerization of the fraction depleted of paraxylene, recycling the mother liquor to the selective adsorption optionally via a clay treatment followed optionally by a distillation of the treatment effluent, and optionally introducing the mother liquor into a distillation unit, wherein the crystallization can comprise several high-temperature stages.
摘要:
An apparatus and process for regulating the flow rate of at least one fluid or effluent circulating in a simulated moving bed comprises a plurality of beds disposed in a closed loop in at least one chromatographic column (1) and comprising at least one means for recirculating fluid and comprising at least two lines for injecting fluid at a controlled flow rate and at least two lines for withdrawing fluid, one of said withdrawal (extract or raffinate) lines being under flow rate control, the other (60) being under pressure control via at least one control valve (6), and is characterized in that said pressure controlled withdrawal line (60) comprises, in addition to the control valve, comprises at least one restriction means (201) enabling the pressure downstream of at least one of the beds to be reduced. One embodiment of the use of the invention is for separating a xylene isomer.
摘要:
The device comprises at least one column 1 that is filled with a number of beds A.sub.n having an adsorbent that are separated by a fluid distributor plate P.sub.i. Each plate is divided into a number of sectors P.sub.10 and P.sub.11, and each sector comprises at least one fluid distribution chamber 13 that is pierced with openings and a circulation space 8 in the vicinity of the openings. The chambers of the plate are connected to a line 10 for transfer to the outside. With respect to the chambers on a plate, transfer line 10 P.sub.i is connected to another transfer line 20 relative to chambers 23 on another plate (P.sub.i+1 or P.sub.i+2) that is arranged downstream by a bypass line L.sub.1,2. The latter comprises means 14, 15, 16 for monitoring and adjustment of the flow of fluid that circulates there, such that the distribution chambers are flushed by a fluid which has approximately the same composition as that of the fluid that circulates through circulation space 8 at each of the chambers.
摘要:
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.
摘要:
For the at least partial separation of aliphatic paraffins into at least one effluent comprising the least branched paraffins and at least one effluent comprising the most branched paraffins, use is made of at least one adsorbent bed comprising at least one grafted microporous solid. A preferred use of the invention relates to the treatment of a charge obtained from an isomerization zone, whereby at least one adsorbent bed makes it possible to separate the charge into a first effluent comprising the normal paraffins and a second effluent, and at least one adsorbent bed on which passes the second effluent, comprising at least one grafted microporous solid, making it possible to obtain a third effluent comprising the monomethyl branched paraffins and a fourth effluent comprising the polymethyl branched paraffins.