Closed loop supercritical and subcritical carbon dioxide extraction system for working with multiple compressed gases

Abstract

A carbon dioxide extraction system which recirculates CO.sub.2 and/or other gases in a continuous loop for maximum extraction efficiency and which recovers substantially all gases at the end of the extraction cycle for cost savings and greater workplace safety. The extractor utilizes a dual pumping system which can incorporate high vapor pressure CO.sub.2 and/or lower vapor pressure gases such as propane, butane, chemical refrigerants such as R134a, and other lower vapor pressure gases. The system allows the operators to work with supercritical CO.sub.2 alone with high pressure liquid pump(s), lower vapor pressure gases alone with modified refrigerant recovery pump(s), or a mixture of CO.sub.2 and lower vapor pressure gases using a combination of high pressure liquid pump(s) for extraction and modified refrigerant recovery pump(s) for full recovery of gases at the end of an extraction cycle.

Claims

1. A system for extracting constituents from a natural product comprising: an extraction vessel; a separator vessel in fluid communication with the extraction vessel; an accumulator vessel in fluid communication with the separator vessel; a refrigerant pump capable of pumping vapor, the refrigerant pump in fluid communication with the accumulator vessel and the extraction vessel; a liquid pump capable of pumping liquid in fluid communication with the accumulator vessel and the extraction vessel; a CO.sub.2 storage vessel; and a lower pressure gas storage vessel, wherein the CO.sub.2 storage vessel and lower pressure gas storage vessel are in fluid communication with the refrigerant pump and the liquid pump.

2. The system for extracting constituents from a natural product of claim 1, wherein the separator vessel is in fluid communication with the refrigerant pump and the liquid pump.

3. The system for extracting constituents from a natural product of claim 1 wherein the extraction vessel communicates with a top of the separator vessel.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 illustrates apparatuses, systems and processes in accordance with embodiments described herein.

DETAILED DESCRIPTION

(2) It will be appreciated that, although specific embodiments of the subject matter of this application have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the disclosed subject matter. Accordingly, the subject matter of this application is not limited except as by the appended claims.

(3) In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with extraction of constituents from natural products, such as botanicals, have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

(4) Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”

(5) Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

(6) The use of ordinals such as first, second and third does not necessarily imply a ranked sense of order, but rather may only distinguish between multiple instances of an act or structure.

(7) The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

(8) Generally described, the present disclosure is directed to examples of systems and methods for utilizing liquefied CO.sub.2 and liquefied gases having a vapor pressure less than the vapor pressure of CO.sub.2 to extract constituents from a natural product in a closed system.

(9) Four different options of systems, apparatuses and processes for extracting constituents from natural products, such as botanicals, are described with reference to FIG. 1. The first option involves an extraction utilizing CO.sub.2 only. As an example of this option, a dried, ground plant material would be sealed within an extractor vessel. Liquefied CO.sub.2 would flow from a CO.sub.2 accumulator vessel into a liquid pump 9 whereby the CO2 is pressurized to the desired extraction pressure in the extractor vessel. A heat exchanger between the pump and extractor vessel controls the temperature of the CO.sub.2 entering the extractor vessel and also determines whether the CO.sub.2 is in a subcritical or supercritical state. These extractions take place at between 900 and 5,000 psi. CO.sub.2 flows through the extraction vessel and dissolves the desired constituents into the liquid CO.sub.2 stream. The CO.sub.2 which is saturated with extract flows through a pressure regulating valve and is depressurized into a solvent constituent separator vessel. The separator vessel is also heated. The combination of an elevated temperature and lower pressure within the separator vessel causes the CO.sub.2 to flash to vapor while the less volatile extract falls into the bottom of the separator. The CO.sub.2 vapor exits the top of the separator and into a cooling tower where it condenses and drops into a CO.sub.2 accumulator. From the CO.sub.2 accumulator, the condensed CO.sub.2 flows back to the liquid pump 9. When the extraction is complete, the CO.sub.2 is pumped back into the accumulator or a separate CO.sub.2 storage tank for re-use at a later time.

(10) The second option utilizes a refrigerant pump 8. A lower vapor pressure gas such as refrigerant R134a, butane or propane is pumped through an extraction vessel. These gases extract efficiently at much lower pressures than CO.sub.2, on the order of about 50 to about 350 psi. The refrigerant pump 8 is capable of pumping liquid or vapor and generates moderate pressures up to 700 psi. In addition the refrigerant pump is capable of pulling a vacuum, e.g., a full vacuum of about 30 inches Hg. The extraction cycle is substantially the same as the CO.sub.2 process described in the first option only it is carried out at lower pressures. The vacuum capability of the refrigerant pump 8 is utilized at the end of the cycle and allows for full recovery of the expensive and potentially harmful and dangerous gases. The vacuum capability of the refrigerant pump 8 also allows an operator to remove air from the system prior to extraction which is valuable when using the flammable lower vapor pressure gases.

(11) In the third option, a combination of CO.sub.2 and a lower vapor pressure gas is used. Examples of a lower vapor pressure gas include those described in the preceding paragraphs. The desired mix of CO.sub.2 and lower vapor pressure gas is pumped into the accumulator prior to extraction. All air is evacuated out of the system after dried, ground plant material is sealed into the extraction vessel. The liquid pump 9 is used to pressurize and circulate the mixed gases through the extraction vessel and into the separator. Due to its higher vapor pressure, CO.sub.2 exits the separator(s) faster than the lower vapor pressure gas(es) causing the lower vapor pressure gas to build up in the separator. To overcome this build up, the refrigerant pump 9 can be engaged periodically throughout the procedure to recover the excess gas from the separator(s) and mix it back into the accumulator to keep the gases mixed properly. At the end of the extraction cycle, all gas will be pumped out of the extractor and back to storage tanks leaving extract in the separator(s).

(12) The fourth option in which the systems, apparatuses and processes described herein can be utilized is a very low pressure, cold, subcritical CO.sub.2 extraction. This type of extraction would take place in the range of 800-900 psi. In accordance with this option, the separator(s) would be kept at a lower pressure of about 500 psi. Due to the difficulty in condensing CO.sub.2 at this pressure, the method utilizes the refrigerant pump in the same manner as a conventional gas booster. CO.sub.2 vapor would exit the separator(s) at about 500 psi and enter the refrigerant pump 8 inlet where it would be compressed, cooled and circulated back through the extractor vessel.

(13) The advantage to using refrigerant pump(s) 8 for this option compared to use of a gas booster is that a refrigerant pump 8 can also pump liquid. Accordingly, upon startup, an operator can quickly fill the extractor vessel with liquid CO.sub.2 and then switch to pumping vapor coming out of the separator(s). Periodic flushing of the refrigerant pump 8 with liquid CO.sub.2 will wash out minute particulates of extracted constituents which are entrained in the CO.sub.2 vapor. These minute particulates if not removed from the refrigerant pump could clog and/or damage the refrigerant pump 8.

(14) The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.

(15) These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.