Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
1999-06-14
2001-06-05
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S175000, C210S511000, C210S774000, C422S063000, C422S070000, C141S329000
Reexamination Certificate
active
06241890
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to supercritical fluid extraction and more particularly relates to a reciprocating pump for pumping liquid near its supercritical temperature in such systems.
In supercritical fluid extraction, an extraction vessel is held at a temperature above the critical point and is supplied with fluid at a pressure above the critical pressure. Under these conditions, the fluid within the extraction vessel is a supercritical fluid. In one type of apparatus for supercritical extraction, there is a specially constructed extraction vessel within a source of heat.
A prior art apparatus for supercritical extraction of this type is described by B. W. Wright, et. al., in
ANAL. CHEM.
59, 38-44 (January 1987) using a glass-lined extraction chamber within a bolted stainless steel extraction vessel heated in an oven. This type of extraction apparatus has the disadvantages of: (1) requiring time consuming steps to open the pressurized extraction vessel before use to insert the sample and again to open it after use to remove the spent sample; and (2) under some circumstances, requiring the handling of a hot extraction vessel.
Prior art apparatuses for automatically changing samples are known. For example, Beckman Instruments, Inc. has produced a radioimmuno and a biogamma analyzer that incorporates a sample changer with an elevator mechanism that raises sample vials from a sample changer to a lead-shielded radiation counting chamber above the sample chamber. Also, a gamma series 300 unit manufactured by Beckman Instruments, Inc., automatically interposes a thick lead shutter that separates the sample vial and the counting chamber from the environment outside the counting chamber. These devices are described in Beckman Bulletin 7250 dated approximately 1972 or 1973. Another apparatus was produced by Micromedic Systems, a division of Rhom and Haas, called the Micromedic Concept 4. It is described in Bulletin M1515 dated 1976.
Two patents describing systems of this type are U.S. Pat. No. 3,257,561 to Packard et al issued Jun. 21, 1966, for RADIOACTIVITY LEVEL DETECTING APPARATUS FOR SAMPLES CARRIED BY PORTABLE TRAYS WITH TRANSFER AND INDEXING MEANS FOR THE TRAYS and U.S. Pat. No. 3,198,948 to Olson issued Aug. 3, 1965, for APPARATUS FOR MEASURING ACTIVITY LEVELS OF RADIOACTIVE SAMPLES.
These devices are not suitable for handling the high temperature, high pressure fluid systems necessary for supercritical extraction.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a novel supercritical extraction technique.
It is a still further object of the invention to provide a novel supercritical extraction apparatus.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that processes a series of samples automatically.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that processes a series of samples automatically but retains the advantages resulting from downward flow of extractant through the pressure vessel and sample.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that self cleans after each extraction.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that can use different sizes of collection vials.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that allows the vials to be interchanged during the extraction process.
It is a still further object of the invention to provide a novel supercritical extraction collection apparatus that improves trapping efficiency by controlling the temperature and pressure of the collection vial and yet is automatically loaded without the need for handling by an operator.
It is a still further object of the invention to provide a novel supercritical extraction collection apparatus that reduces collection solvent loss by controlling the temperature and pressure of the vial and yet is automatically loaded without the need of handling by an operator.
It is a still further object of the invention to provide a novel supercritical extraction collection apparatus that avoids restrictor plugging by controlling the temperature of the collection vial and yet is automatically loaded without the need for handling by an operator.
It is a still further object of the invention to provide a novel supercritical extraction collection apparatus that precools the vial prior to extracting.
It is a still further object of the invention to provide a novel supercritical extraction apparatus that refills the collection vials with solvent during extraction or after the extraction is complete.
In accordance with the above and further objects of the invention, a supercritical fluid extraction system includes a cartridge capable of holding the sample to be extracted, a pressure vessel into which the cartridge fits and a pumping system. The pressure vessel fits into a heater and the cartridge is removably mounted to a breech plug that seals the pressure vessel. There are separate outlets for the cartridge and pressure vessel to permit equalization of pressure on the inside and outside of the cartridge without contamination from impurities outside the cartridge but inside the pressure vessel.
To permit programmable valves to open and close and thus control the flow of high pressure fluids into the pressure chamber of a supercritical fluid extractor, a motor driven valve has a valve seat that receives a spherical or ball-shaped valve element and a valve stem that is moved reciprocally under motor control to force the valve element into the seat or to release it. The ball is free to rotate upon being released and the supercritical fluid flows past the ball through the seat and into the pressure vessel.
To avoid scarring the ball as it rotates, which would reduce its life, the face of the stem is harder than the valve seat but not as hard as the surface of the spherical valve element. The spherical valve element is much harder than the valve seat, and the valve seat has a hardness sufficient to withstand a pressure of 20,000 psi without substantial scarring.
To automate the operation under the control of a microprocessor, a motor operated fraction collector, a motor operated sample source and a motor operated sample injector automatically move samples and collection containers into an extraction station, inject samples into the extraction pressure vessel, perform extraction and collect extractant in different appropriate collection containers in a timed sequence to permit extracting of a series of samples with minimum human handling.
In the preferred embodiment, a movable motor member is aligned: (1) with an opening in a sample cartridge reel that moves sample cartridges carrying samples into the extraction station; and (2) with an opening in the extraction pressure vessel. The movable member is dimensioned to be capable of sealing a correspondingly sized opening in the pressure vessel and adapted to move the sample cartridge into the pressure vessel and seal the pressure vessel. Motors are provided to operate the valves to permit the extraction operation on the cartridge. The movable member is removed from the pressure vessel after extraction and returns the sample cartridge back to the sample reel.
In operation, the sample to be extracted is placed within the cartridge and the cartridge inserted into and sealed within a pressure vessel. Upon insertion, one of two outlet fittings communicates with the interior of the cartridge and the other with the interior of the pressure vessel outside the cartridge. An inlet to the pressure vessel communicates with the outlet of a pump which pumps the supercritical fluid along a path that heats it and through a programmable valve into the interior of the pressure vessel and extraction cartridge. For each extraction, the valve is automatically opened by a computer controlled motor that releases a valve element to permit flow and closes it to
Allington Robert W.
Clay Dale Lee
Jameson Daniel Gene
Liescheski, III Philip Bernard
Winter Robin Randall
Carney Vincent L.
Drodge Joseph W.
Isco, Inc.
LandOfFree
Apparatus and method for supercritical fluid extraction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for supercritical fluid extraction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for supercritical fluid extraction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2529601