Simulated moving bed separation method and device with bypass fluid flow

Patent metadata

Field	Value
Publication number	US-10675559-B2
Application number	US-201916441547-A
Country	US
Kind code	B2
Filing date	Jun 14, 2019
Priority date	Jun 20, 2018
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

Method for the simulated moving bed separation of a feedstock (F), in which when a fluid/effluent (feedstock F, desorbent D, extract E, raffinate R) is injected/withdrawn into/from a chosen plate (P i ) using an external bypass line (L i−1/i , L i/i+1 ) connected to said chosen plate (P i ), the flow rate within the said external bypass line (L i−1/i , L i/i+1 ) is controlled in such a way that: a major proportion of the fluid/effluent (F, D, E, R) is injected/withdrawn into/from the chosen plate (P i ); and a minor proportion of the fluid/effluent (F, D, E, R) is injected/withdrawn into/from the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i−1/i , L i/i+1 ).

First claim

The invention claimed is:

1. Method for the simulated moving bed separation of a feedstock (F) in a simulated moving bed separation device,
the device comprising:

at least one column comprising a plurality of beds of adsorbent (A i ) which are separated by plates (P i ) each comprising a distribution/extraction system; and
external bypass lines (L i/i+1 ) directly joining two successive plates (P i , P i+1 ), each external bypass line comprising fluid (F, D) feed points and effluent (E, R) withdrawal points,
in which method:
the at least one column is fed with the feedstock (F) and a desorbent (D) and at least one extract (E) and at least one raffinate (R) is withdrawn from the at least one column, the feed and withdrawal points being shifted during the course of time by an amount corresponding to one adsorbent bed with a changeover period (ST) and determining a plurality of operating zones of the device, and notably the following main zones:

a zone 1 for the desorption of the compounds from the extract, this zone being comprised between the feed for the desorbent (D) and the withdrawal of the extract (E),
a zone 2 for the desorption of the compounds from the raffinate, this zone being comprised between the withdrawal of the extract (E) and the feed for the feedstock (F),
a zone 3 for the adsorption of the compounds from the extract, this zone being comprised between the feed for the feedstock (F) and the withdrawal of the raffinate (R), and
a zone 4 situated between the withdrawal of the raffinate (R) and the feed for the desorbent (D);
when a fluid (F, D) is injected towards a chosen plate (P i ) via an external bypass line (L i−1/i , L i/i+1 ) connected to the said chosen plate (P i ), the flow rate within the said external bypass line (L i−1/i , L i/i+1 ) is controlled in such a way that a major proportion of the fluid (F, D) is injected towards the chosen plate (P i ), and that a minor proportion of the fluid (F, D) is injected towards the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i−1/i , L i/i+1 ); and/or
when an effluent (E, R) is withdrawn from a chosen plate (P i ) via an external bypass line (L i−1/i , L i/i+1 ) connected to the said chosen plate (P i ), the flow rate within the said external bypass line (L i−1/i , L i/i+1 ) is controlled in such a way that a major proportion of the effluent (E, R) is withdrawn from the chosen plate (P i ), and that a minor proportion of the effluent (E, R) is withdrawn from the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i−1/i , L i/i+l ).

2. Method according to claim 1 , in which:
the minor proportion of the fluid (F, D) injected towards the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i−1/i , L i/i+1 ) is regulated in such a way that a level of rinsing of the said adjacent plate (P i−1 , P i+1 ) is equal to 100% +/−30%; and/or
the minor proportion of the effluent (E, R) withdrawn from the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i+1/i , L i/i+1 ) is regulated in such a way that a level of rinsing of the said adjacent plate (P i−1 , P i+1 ) is equal to 100% +/−30%,

the adjacent plate (P i−1 , P i+1 ) being the upstream adjacent plate (P i−1 ) positioned upstream of the chosen plate (P i ), or the downstream adjacent plate (P i+1 ) positioned downstream of the chosen plate (P i ),
the level of rinsing of the upstream adjacent plate (P i−1 ) being defined by Q i−1 x ST/(V i−1 +VL i−1/i /2
the level of rinsing of the downstream adjacent plate (P i−1 ) being defined by Q i+1 i x ST/(V i+1 +VL i/i+1 /2),
n being the number of adsorbent beds in the column,
i being a natural whole number comprised between 1 and n,
Q i−1 denoting the volumetric flow rate flowing from the upstream adjacent plate (P i−1 ),
Q i+1 denoting the volumetric flow rate flowing towards the downstream adjacent plate (P i−1 );
V i−1 denoting the volume of the distribution/extraction system of the upstream adjacent plate (P i−1 );
V i+1 denoting the volume of the distribution/extraction system of the downstream adjacent plate (P i+1 );
VL i−1/i denoting the volume of the upstream external bypass line (L i−1/i ) between the upstream adjacent plate (P i−1 ) and the chosen plate (P i ),
VL i/i+1 denoting the volume of the downstream external bypass line (L i/i+1 ) between the chosen plate (P i ) and the downstream adjacent plate (P i+1 ),
ST denoting the changeover period.

3. Method according to claim 2 , in which:
the minor proportion of the fluid (F, D) injected towards the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line (L i−1/i , L i/i+1 ) is regulated in such a way that a level of rinsing of the said adjacent plate (P i−1 , P i+1 ) is equal to 100% +/−20%; and/or
the minor proportion of the effluent (E, R) withdrawn from the adjacent plate (P i−1 , P i+1 ) connected to the said external bypass line L i+1 /i, L i/i+1 ) is regulated in such a way that a level of rinsing of the said adjacent plate (P i−1 , P i+1 ) is equal to 100% +/−20%.

4. Method according to claim 1 , in which:
synchronism to within plus or minus 10% is established in each other external bypass line (L j /L j+1 ),

the synchronism flow rate being defined by (V j +V j+1 +V j/j+1 )/ST,
j being a natural whole number comprised between 1 and n and different from i,
n being the number of adsorbent beds in the column,
i being a natural whole number comprised between 1 and n,
V j and V j+1 denoting the respective volumes of the distribution/extraction systems of the plates (P j and P j+1 ) connected to the said other external bypass line (L j /L j+1 ),
VL j/j+1 denoting the volume of the said other external bypass line (L j /L j+1 ),
ST denoting the changeover period.

5. Method according to claim 4 , in which synchronism to within plus or minus 5% is established in each other external bypass line (L j /L j+1 ).

6. Method according to claim 2 , in which n is a natural whole number comprised between 6 and 24.

7. Method according to claim 1 , in which each plate (P i ) is connected to an upstream external bypass line (L i+1/i ) between the upstream adjacent plate (P i+1 ) and the said plate (P i ), and/or to a downstream external bypass line (L i/i+1 ) between the said plate (P i ) and the downstream adjacent plate (P i+1 ).

8. Method according to claim 1 , in which each plate (P i ) comprises a plurality of distribution—mixing—extraction panels of the parallel sectors type with asymmetric feed.

9. Method according to claim 1 , in which the feedstock (F) contains paraxylene or metaxylene within a mixture of C8 aromatic hydrocarbons.

Assignees

• Ifp Energies Now

Inventors

• Leinekugel Le Cocq Damien
• Hotier Gerard
• Le Goff Pierre-Yves
• Lambert Fabian

Classifications

• B01D15/1835 Primary

  Flushing · CPC title

• B01D15/185

  characterised by the components to be separated · CPC title

• B01D2215/026

  Operations & Transport · mapped topic

• C07C7/13

  by molecular-sieve technique · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title