Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
  • C11B9/00—Essential oils; Perfumes
  • C11B9/02—Recovery or refining of essential oils from raw materials
  • C11B9/025—Recovery by solvent extraction
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES, NOT OTHERWISE PROVIDED FOR; PREPARATION OR TREATMENT THEREOF
  • A23L27/00—Spices; Flavouring agents or condiments; Artificial sweetening agents; Table salts; Dietetic salt substitutes; Preparation or treatment thereof
  • A23L27/10—Natural spices, flavouring agents or condiments; Extracts thereof
  • A23L27/11—Natural spices, flavouring agents or condiments; Extracts thereof obtained by solvent extraction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D11/00—Solvent extraction
  • B01D11/02—Solvent extraction of solids
  • B01D11/0203—Solvent extraction of solids with a supercritical fluid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D11/00—Solvent extraction
  • B01D11/02—Solvent extraction of solids
  • B01D11/0288—Applications, solvents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D11/00—Solvent extraction
  • B01D11/02—Solvent extraction of solids
  • B01D11/0292—Treatment of the solvent
  • B01D11/0296—Condensation of solvent vapours

Definitions

• This invention concerns apparatuses and a method for "extraction” of biomass, i.e. the extraction of flavours, fragrances or pharmaceutically active ingredients from materials of natural origin (these materials being referred to as “biomass” herein).
• biomass materials include but are not limited to flavoursome or aromatic substances such as coriander, cloves, star anise, coffee, orange juice, fennel seeds, cumin, ginger and other kinds of bark, leaves, flowers, fruit, roots, rhizomes and seeds.
• Biomass may also be extracted in the form of biologically active substances such as pesticides and pharmaceutically active substances or precursors thereto, obtainable e.g. from plant material, a cell culture or a fermentation broth.
• solvents include liquefied carbon dioxide or, of particular interest, a family of chlorine-free solvents based on organic hydrofluorocarbon (HFC) species.
• HFC organic hydrofluorocarbon
• hydrofluorocarbon we are referring to materials which contain carbon, hydrogen and fluorine atoms only and which are thus chlorine-free.
• Preferred hydrofluorocarbons are the hydrofluoroalkanes and particularly the Ci-t hydrofluoroalkanes.
• Suitable examples of C ⁇ -4 hydrofluoroalkanes which may be used as solvents include, inter alia, trifluoromethane (R-23), fluoromethane (R-41), difluoromethane (R-32), pentafluoroethane (R-125), 1,1 ,1-trifluoroethane (R-143a), 1,1,2,2-tetrafluoroethane (R-134), 1,1 ,1,2- tetrafluoroethane (R-134a), 1,1-difluoroethane (R-152a), heptafluoropropanes and particularly 1 ,1,1,2,3,3,3-heptafluoropropane (R-227ae), 1 ,1 ,1,2,3,3- hexafluoropropane (R-236ea), 1 ,
• R-134a, R-227ea, R-32, R-125, R-245ca and R-245fa are preferred.
• An especially preferred hydrofluorocarbon for use in the present invention is 1,1,1,2-tetrafluoroethane (R-134a).
• CFC's chlorofluorocarbons
• HCFC's hydrochlorofluorocarbons
• liquefied solvent is allowed to percolate by gravity in downflow through a bed of biomass held in vessel 11. Thence it flows to evaporator 12 where the volatile solvent vapour is vaporised by heat exchange with a hot fluid.
• the vapour from evaporator 12 is then compressed by compressor 13: the compressed vapour is next fed to a condenser 14 where it is liquefied by heat exchange with a cold fluid.
• the liquefied solvent is then optionally collected in intermediate storage vessel 15 or returned directly to the extraction vessel 1 to complete the circuit.
• a feature of this process is that the principal driving force for circulation of solvent through the biomass and around the system is the difference in pressure between the condenser/storage vessel and the evaporator. This difference in pressure is generated by the compressor. Thus to increase the solvent circulation rate through the biomass it is necessary to increase this pressure difference, requiring a larger and more powerful compressor.
• a potential problem for efficient design of equipment arises because it is known that, for most extractions, the rate at which the majority of the extract material is removed from the biomass is influenced by the rate at which solvent flows through the bed. A faster solvent rate gives better mass transfer from the biomass to the solvent, enabling more material to be removed for a given period of time. Consequently the size of compressor 13 selected for the apparatus 10 ultimately determines the rate at which the material may be extracted and therefore affects the time taken to effect an extraction.
• Equipment designed for this type of extraction process is typically used for multiple extractions of different biomasses, yielding a range of products which may need to be extracted to meet a variety of customers' production schedules.
• the biomasses of interest to industry can range from relatively large, pellet-like seeds or beans, to much finer powdered or shredded vegetation.
• Heat recovery is often employed in such processes to reduce the cost of operating the process. This can be achieved by either of two methods: direct or indirect heat integration.
• the solvent condenser 14 is combined with the solvent evaporator 12.
• the hot, compressed solvent vapour is condensed in this unit and acts as the hot fluid for the vaporisation of solvent in the evaporator.
• a portion of the flow of heated cooling medium (typically water) from the condenser 14 is used to supply heat to the solvent evaporator.
• the solvent circuit acts as a vapour compression heat pump.
• the thermodynamic efficiency of such a device is inversely proportional to the difference between vaporisation and condensation temperature of the working fluid.
• the invention seeks to solve or at least ameliorate one or more of the drawbacks of the prior art. According to a first aspect of the invention there is provided an apparatus according to Claim 1.
• This arrangement advantageously allows variation of the liquid circulation rate through the biomass being extracted in a closed-loop solvent extraction circuit of the general functionality defined above, without need to alter the size or operating conditions of a solvent vapour compressor.
• the extraction vessel contains a packed bed of biomass.
• the designer can therefore select an operating condition for the compressor and associated evaporator and condenser which gives an optimum operating condition by e.g. using a minimal pressure difference between condenser and evaporator.
• the pump eliminates the possibility of a vapour gap in the extractor vessel and provides sufficient pressure to eliminate the potential problems of flash vapour mentioned above.
• Preferred embodiments of a circuit embodying the invention are defined in Claims 3 and 6.
• Preferred kinds of modifiable resistance to flow are defined in Claims 4,5,7 and 8.
• Claim 9 defines preferred control arrangements for the modifiable resistances.
• the apparatos may include a solvent storage vessel having an inlet and an outlet and being connected in parallel with the solvent recirculation loop. More particularly the solvent storage vessel is connected in-line between the condenser and the extraction vessel.
• the recirculation pump pumps recirculated solvent upwards through a bed of biomass in the extraction vessel.
• the recirculation pump pumps recirculated solvent downwards through a bed of biomass in the extraction vessel. It is believed that other directions of solvent flow are possible.
• an apparatus as defined in Claim 14 is particularly suited to form part of the Claim 1 apparatos, which for the first time allows use of a packed biomass bed.
• the density of biomass in the packed bed is in the range of 750kg/m 3 - 1000kg/m 3 .
• This method may advantageously be practised using the apparatus of any of Claims 1 to 15.
• the method sub-step of pumping the quantity of solvent through the packed bed of biomass may involve upward flow of the solvent through the biomass, downward flow, or flow through the biomass in another direction.
• Figure 1 is a schematic representation of a prior art closed loop biomass extraction apparatus
• Figure 2 is a schematic representation of a first embodiment of apparatus according to the invention.
• Figure 3 is a schematic representation of a second embodiment of apparatos according to the invention.
• Figure 4 is a schematic representation of a third embodiment of apparatos according to the invention.
• FIG. 2 there is shown a part of the Figure 1 circuit, modified in accordance with the invention. The remainder of the circuit part- illustrated in Figure 2 is as shown in Figure 1.
• the complete apparatos includes operatively connected in series, an extraction vessel 11, for containing biomass, that permits a solvent or a solvent mixture to contact biomass to effect extraction; an evaporator for separating solvent and biomass extract from one another; (optionally) a compressor for compressing gaseous solvent; and a condenser for condensing pressurised solvent for retorn to the extraction vessel.
• Figure 2 also includes the receiver 15 that is optional in the Figure 1 arrangement.
• Figure 2 shows a pumped recirculation loop 20 for recirculating a portion of the output of the extraction vessel 11 for further contact with the biomass; and modifiable flow resistances, in the form of flow control valve 21 and flow restrictor 23.
• a main branch 22a of the delivery line connects to the evaporator 12 and includes an in line flow restrictor such as a nozzle or, as shown, an orifice plate 23.
• a recirculation branch 22b of the delivery line that conveys solvent that has contacted the biomass and biomass extract entrained therewith, is connected to the inlet side of the extraction vessel 11.
• Recirculation branch 22b includes, operatively connected in series, adjustable flow control valve 21 and pump 26.
• the output of pump 26 connects directly to the inlet side of extraction vessel 11.
• the oudet of receiver 15 is, in parallel to recirculation branch 22b, connected as an additional input to pump 26.
• solvent from the receiver or storage vessel 15 is circulated through the extraction vessel 11 by solvent circulation pump 3.
• Flow control valve 21 in the solvent recirculation line 22b is controlled (e.g. electronically or using a computer) to allow a portion of the solvent liquor to return to the suction side of the pump while the balance of the solvent flow is allowed to feed forward through delivery line 22b to the solvent evaporation stage of the process.
• Orifice plate 23 is optionally incorporated in the delivery line to aid the balancing of flow resistance in the delivery and recirculation lines.
• FIG 3 shows a second embodiment of the invention. This embodiment is the same as the Figure 2 embodiment, except that the adjustable valve 21 and orifice 23 are transposed.
• the adjustable valve 21 acts to control the quantity of solvent liquor that is fed forward to the evaporator 12, rather than controlling the amount of solvent/extract liquor that enters the recirculation branch line 22b. Nonetheless the effect remains that of controlling the flow rate of solvent around the closed loop 20.
• FIG. 4 A third embodiment of the invention is shown in Figure 4.
• adjustable flow control valves 21a, 21b are present in both the recirculation and delivery lines 22b, 22a. In use this allows continuous control of both the solvent rate through the biomass and the liquid level in the receiver 15.
• the recirculation line valve 21b is used to set total flow while the valve 21a on the delivery line 22a is used to control liquid level (and hence system solvent mass balance). This principle can readily be extended to control the level in the solvent condenser rather than in the solvent receiver if so desired.
• the invention reduces the driving force (concentration difference) available for mass transfer and so as the extraction proceeds, depending on process economics for a given biomass, it may be beneficial to continuously alter the recirculation rate so that an optimal overall rate of extraction is attained. Such alteration could be carried out manually or under automatic control.
• the invention relates to biomass extractions performed using a closed loop process of the general type displayed in Figure 1. • It allows independent variation of the rate of circulation of solvent through the biomass without increasing the size of solvent vapour compressor required.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Wood Science & Technology (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Health & Medical Sciences (AREA)
• Nutrition Science (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Extraction Or Liquid Replacement (AREA)
• Compounds Of Unknown Constitution (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Citations (5)

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• 1999
  • 1999-09-06 GB GBGB9920946.2A patent/GB9920946D0/en not_active Ceased
• 2000
  • 2000-08-29 GB GB0020998A patent/GB2353730B/en not_active Expired - Fee Related
  • 2000-09-01 JP JP2001521426A patent/JP2003508206A/ja not_active Withdrawn
  • 2000-09-01 CA CA002383593A patent/CA2383593A1/en not_active Abandoned
  • 2000-09-01 WO PCT/GB2000/003341 patent/WO2001017644A1/en not_active Ceased
  • 2000-09-01 EP EP00956692A patent/EP1210159A1/en not_active Ceased
  • 2000-09-01 AU AU68559/00A patent/AU779527B2/en not_active Ceased
  • 2000-09-01 IL IL14847900A patent/IL148479A0/xx unknown
  • 2000-09-05 US US09/655,631 patent/US6667015B1/en not_active Expired - Fee Related
• 2002
  • 2002-03-01 ZA ZA200201748A patent/ZA200201748B/en unknown

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