METHOD AND INSTALLATION FOR REGULATING THE MODIFIER LEVEL IN CHROMATOGRAPHY OR SUPERCRITICAL EXTRACTION WITH RECYCLING

• US 20090206037A1
• Filed: 08/11/2006
• Published: 08/20/2009
• Est. Priority Date: 08/12/2005
• Status: Active Grant

• Current Assignee: PIC Solution
• Original Assignee: PIC Solution
• Inventors: Shaimi, Mohamed
• Granted Patent: US 8,114,282 B2
• Time in Patent Office: Days
• US Class Current: 210/639
• CPC Class Codes: B01D 15/166 Fluid composition conditioning, e.g. gradient
• CPC Class Codes: B01D 15/1814 recycling of the fraction to be distributed
• CPC Class Codes: B01D 15/40 using supercritical fluid as mobile phase or eluent

Abstract

A chromatography or supercritical extraction method is disclosed, in which the eluent comprises a mixture of a fluid and a modifier and in which the fluid is recycled. One exemplary method comprises an operation consisting in determining at least one quantity linked to the level of modifier that is mixed with the recycled fluid and, if necessary, a correction operation in order to limit variations in the level of modifier in the eluent at the inlet of the column or the extractor. The disclosure also relates to a chromatography or extraction installation.

Claims

1. A chromatography or extraction method, including:

a separating operation (1) in a column or an extractor, with the said column or the said extractor receiving a product (P) and feeding into an eluent that includes a supercritical fluid, routed via a first pumping operation (2), and a modifier, routed via at least one second pumping operation (3),

an operation (4) for collecting at least one fraction of the product (P) downstream of the column or extractor,

an operation (5) for recycling the supercritical fluid mixed with a residual quantity of modifier, following after the collecting operation (4) and preceding the first pumping operation (2), with the said first pumping operation being used to pump at least the said supercritical fluid mixed with a residual quantity of modifier, and

a condensing operation (6) following after the collecting operation (4) and preceding the first pumping operation (2),

the said method being characterised in that it further includes;

downstream of the collecting operation (4) and upstream of the separating operation (1), an operation for determining at least one magnitude associated with the level of modifier mixed with the recycled supercritical fluid, and if necessary

an operation (8) for correcting the flow in the first pumping operation (2) and the flow in the second pumping operation (3), in order to limit the variations, during execution of the method, of the modifier level in the eluent at the input to the column or of the extractor, in a direction that is suitable for meeting a first setpoint, determined beforehand, for the total flow corresponding to the sum of the flows in the first-pumping operation (2) and in the second pumping operation (3).

2. The method according to claim 1, wherein the operation (7) for determining at least one magnitude associated with the level of modifier mixed with the recycled supercritical fluid takes place upstream of the first and second pumping operations (2, 3) and includes:

an operation to measure, at one measuring point at least, the density of the recycled supercritical fluid mixed with a residual quantity of modifier, and

an operation for evaluating the level of modifier mixed with the recycled supercritical fluid, with the modifier level being evaluated, from the measured density, by means of a density=f (modifier level) calibration curve, established beforehand at the pressure and the temperature existing at the measuring point and around the latter; and

wherein the correction operation (8) consists of modifying the flow in the first pumping operation (2) and the flow in the second pumping operation (3) in order to meet the first setpoint and a second setpoint, set beforehand, of levels of modifier in the eluent.

3. The method according to claim 2, wherein the first pumping operation (2) and the second pumping operation (3) take place in parallel with each other.

4. The method according to claim 2, wherein the second pumping operation (3) takes place upstream of the first pumping operation (2).

5. The method according to claim 1, wherein the operation (7) for determining a magnitude associated with the modifier level in the eluent consists of measuring the density of the eluent upstream of the first pumping operation (2) and downstream of the second pumping operation (3), and

wherein the correction operation (8) consists of modifying the flow in the first pumping operation (2) and the flow in the second pumping operation (3) in a direction that is suitable to attain the first setpoint and a third setpoint, set beforehand, for the density of the eluent.

6. The method according to claim 1, wherein the operation (7) for determining at least one magnitude associated with the level of modifier mixed with the recycled supercritical fluid is effected downstream of the condensing operation (6).

7. The method according to claim 1, wherein the operation (7) for determining at least one magnitude associated with the level of modifier mixed with the recycled supercritical fluid is effected upstream of the condensing operation (6).

8. The method according to claim 1, wherein the supercritical fluid is carbon dioxide.

9. The method according to claim 1, wherein the modifier is an organic liquid solvent, like an alcohol for example.

10. The method according to claim 1, further including at least one operation (9) for regulating the pressure followed by at least one operation (10) for regulating the temperature, downstream of the separating operation (1) and upstream of the collecting operation (4).

11. A chromatography or extraction installation including:

a separating device such as one or more chromatography columns (12) or an extractor, which receives a product (P) and feeds into an eluent that includes a supercritical fluid, routed via a first pump (13), and a modifier, routed via at least one second pump (14),

a device (15) for collecting at least one fraction of the product (P) separated in the separating device,

a path (16) for recycling the supercritical fluid mixed with a residual quantity of modifier, downstream of the collecting device (15) and upstream of the first pump (13), with the said first pump pumping at least the said supercritical fluid mixed with a residual quantity of modifier, and

a condenser (17) placed downstream of the collecting device (15) and upstream of the first pump (13),

the said installation being characterised in that it further includes a measuring and correcting device (18), placed in the recycling path (16) or in, downstream of the first pump (13) and upstream of the separating device, which measures at least one magnitude associated with the level of modifier mixed with the recycled supercritical fluid and that, if necessary, performs correction of the flow in the first pump (13) and of the flow in the second pump (14), in order to limit the variations, while running the installation, of the said levels at the input to the separating device, in a direction that is suitable for meeting a first setpoint, determined beforehand, for the total flow corresponding to the sum of the flows in the first pump (13) and in the second pump (14).

12. The installation according to claim 11, wherein the measuring and correcting device (18) is positioned at a measuring point located upstream of the first and second pumps (13, 14) and measures the density of the recycled supercritical fluid, mixed with a residual quantity of modifier, from which it evaluates the level of modifier mixed with the recycled supercritical fluid by means of a pre-established density=f (modifier level) calibration curve at the pressure and the temperature existing at the measuring point and around the latter;

and

wherein the said of measuring and correcting device (18) modifies the flow in the first pump (13) and the flow in the second pump (14) in order to attain the first setpoint and a second setpoint, set beforehand, of modifier level in the eluent.

13. The installation according to claim 12, wherein the first pump (13) and the second pump (14) are mounted in parallel with each other.

14. The installation according to claim 12 wherein the second pump (14) is positioned upstream of the first pump (13).

15. The installation according to claim 11, wherein the measuring and correcting device (18) measures the density of the eluent upstream of the first pump (13) and downstream of the second pump (14), and modifies the flow in the first pump (13) and the flow in the second pump (14) in a direction that is suitable for meeting the first setpoint and a third setpoint, fixed beforehand, for the density of the eluent.

16. The installation according to claim 11, wherein the measuring and correcting device (18) is placed downstream of the condenser (17).

17. The installation according to claim 11, wherein the measuring and correcting device (18) is placed upstream of the condenser (17).

18. The installation according to claim 11, further including a device to regulate the pressure, such as a pressure-reducer for example (19), followed by a device to regulate the temperature of the eluent, by heating it for example, downstream of the separating device and upstream of the collecting device (15).