US3656240A - Freeze-dryer - Google Patents

Freeze-dryer Download PDF

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Publication number
US3656240A
US3656240A US37975A US3656240DA US3656240A US 3656240 A US3656240 A US 3656240A US 37975 A US37975 A US 37975A US 3656240D A US3656240D A US 3656240DA US 3656240 A US3656240 A US 3656240A
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United States
Prior art keywords
liquid
chamber
freeze
duct
ducts
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Expired - Lifetime
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US37975A
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English (en)
Inventor
Nicolaas Antonie Van Dijk
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US Philips Corp
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US Philips Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/06—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum the process involving freezing

Definitions

  • Trifari ABSTRACT The invention provides a freeze-dryer of a simple construction in which the freeze-drying temperature of the vacuum chamber and the temperature of the condenser chamber which is at a lower level are adjusted by means of a liquid conducted along the cold head of a cold-gas refrigerator. This liquid is also advantageously used for defrosting the ice mass formed in the condenser chamber in a very short period of time, after the freeze-drying process.
  • the invention relates to a freeze-dryer comprising at least one vacuum freeze-drying chamber communicating with a condenser chamber in which a lower temperature prevails during operation than in the vacuum chamber; a cold-producing device for supplying cold to the chambers, including a heating device is present for controlling the operating temperature of the vacuum chamber.
  • the cold producing device is formed by an evaporation-condensation refrigerator in which a gas is compressed to a high pressure by one or more compressors, is then condensed in a condenser and expanded in one or more throttle devices.
  • liquid medium is supplied to a vaporizer arranged in the condenser chamber where it evaporates by the withdrawal of heat from the condense chamber and flows back to the compressor.
  • liquid medium is conducted to a second vaporizer which is in a heat exchanging contact with a liquid present in a closed system of ducts, supplies its cold to said liquid and flows back to the compressor again in the gaseous phase.
  • the liquid can circulate and again supply cold taken up from the second vaporizer in one part of the system of ducts, to the vacuum chamber which is in heat exchanging contact with another part of the system of ducts.
  • a heating device is present in the closed system of ducts by means of which the temperature of the cooled liquid and hence the temperature of the vacuum chamber can be controlled.
  • the vacuum chamber is evacuated by means of a vacuum pumping device communicating with the condenser chamber.
  • aqueous preparations which have been frozen at -50 C., for example outside the freeze-dryer, are placed in the vacuum chamber which has previously been cooled, to 30 C., for example.
  • the vacuum chamber is then evacuated and it is ensured, by supplying thermal energy to the vacuum chamber via the liquid in the closed system of ducts, that the ice present in the preparations sublimes to water vapor.
  • This water vapor is drawn off to the condenser chamber cooled at a lower temperature, condenses therein and freezes to the cold surface of the condenser chamber.
  • the cooling of the condenser chamber generally occurs to temperatures of approximately 80 while the temperature of the vacuum chamber is controlled from +3 C. to -30 to 40 C.
  • This known freeze dryer has a few drawbacks.
  • the dryer is comparatively complicated, which is due to the fact, that in order to be able to reach cooling temperatures to 80 C., at least one low-pressure compressor and one high pressure compressor are required to obtain a high compression/expansion pressure ratio of the gas.
  • An additional difficulty is that special precautions are necessary to return lubricating oil originating from the compressors and taken along by the compressed gas to said compressors.
  • the time necessary to defrost the ice formed in the condenser chamber is very long. This is caused by the fact that the defrosting should be carried out at comparatively low temperatures since otherwise the gas pressure in the system of ducts would become inadmissibly high.
  • the defrosting is carried out by means of water of, for example, 40 C. The condition, whereby the water can transfer its heat only to the outside of the ice mass (the ice surrounds the vaporizer arranged in the condenser chamber for The greater part) results in a further unfavorable influencing of the defrosting time.
  • the freeze-dryer according to the invention is characterized in that the cold-producing device is formed by a cold gas refrigerator, a first closed system of ducts being present which comprises a first heat exchanger for exchanging heat with the cold-gas refrigerator, and also comprises a second heat exchanger arranged in the condenser chamber, a liquid and a first pumping device being present in said system, a system of ducts being furthermore present which communicates on either side of the first heat exchanger with the first system of ducts and in which a third heat exchanger is present arranged in the vacuum chamber,
  • the liquid present in the freeze-dryer according to the invention can also be used for defrosting the condenser chamber.
  • the temperature of the liquid suitably chosen for that purpose, is the systems of ducts may now be sure which is lower than 1 atm. at comparatively low temperahigh without the danger of too high a pressure in the ducts.
  • At least one of the systems of ducts communicates with a liquid expansion container in which a gaseous medium is present above the liquid under such a pressure that, at any operating temperature of the liquid, boiling of said liquid is prevented.
  • a gaseous medium is present above the liquid under such a pressure that, at any operating temperature of the liquid, boiling of said liquid is prevented.
  • a further favorable embodiment of the freeze-dryer according to the invention in which the operating temperature of the vacuum chamber is controlled within the range of from approximately 30 to -H- C. and the operating temperature of the condenser chamber is approximately 80 C. is characterized in that the liquid is R11 (trichlormonofiuoromethane- CC1 F.).
  • R11 trifluorofluoride- CC1 F.
  • the use of this known liquid presents various advantages. First of all the viscosity of said liquid (boiling point 23.8 C.) in the operative temperature range is rather constant. This means that in the temperature range considered a good heat transfer is maintained between the liquid and the heat exchangers. Actually, the danger that the normally turbulant flow of liquid in the systems of ducts decreases at comparatively low temperatures of the liquid owing to the increased viscosity and changes into a laminar flow is absent here.
  • FIG. 1a shows not to scale an embodiment of the freeze dryer.
  • FIGS lb and 1c shows a slightly different embodiment of the part of the freeze-dryer shown in FIG. la on the right hand side of the lines I-I.
  • FIG. 1a denotes a first closed system of ducts in which a heat-exchanger 2 is incorporated which is in a heat exchanging contact with the cold head 3 of a cold-gas refrigerator 4, and in which a heat exchanger 5 is arranged in a condense chamber 6.
  • the condenser chamber communicates via a duct 7 with a vacuum freeze-drying chamber 8, and communicates via a duct 9 with a vacuum pumping device 10. It furthermore comprises a water inlet 6' and a water outlet 6".
  • a second system of ducts 11 communicates with the first system of ducts l; the second system of ducts a heat exchanger 12 is incorporated which is arranged in the vacuum freeze-drying chamber 8.
  • a bypass duct 13 with controllable cock 14 communicates with the second system of ducts 11.
  • a pumping device 15 is present in the first system of ducts 1, while in the second system of ducts a controllable cock 16, a heating device 17 and a pumping device 18 are incorporated.
  • an expansion container 19 comprising a valve 20 communicates with the first system of ducts 1.
  • the systems of ducts are filled with a liquid which may be, for example, R11.
  • a liquid which may be, for example, R11.
  • a gas under pressure for example, nitrogen, is present.
  • the heat exchanger 2 has a resistance to flow which is considerably larger than that of the heat exchanger 5.
  • Cooling of the condenser chamber 6 takes place by circulating liquid in the system of ducts 1 by means of the pumping device 15 in the direction denoted by the solid-line arrows.
  • Cold absorbed by the liquid at the cold head 3 of the refrigerator 4 in the heat exchanger 2 is delivered again to the condenser chamber in the heat exchanger 5.
  • R11 also makes it possible to heat the liquid to comparatively high temperatures upon defrosting the moisture receiving chamber while at the same time the pressure in the expansion container and the systems of ducts can be comparatively low so that thin-walled and low-weight ducts can be used. It is possible, for example, to heat R11, at a pressure of 2.5 atmospheres in the systems of ducts, to C. without the danger of boiling occuring.
  • the vacuum freeze-drying chamber can be brought to the desirable temperature, a temperature which is higher than that so which the condenser chamber is adjusted. If it is desired that much cold be supplied to the heat exchanger 12, the cock 14 can be closed so that the overall quantity of liquid displaced by the pumping device 18 flows to point B and then to the heat exchanger 2.
  • the vacuum freeze-drying chamber 8 and the con-- water vapor condenses and freezes in the condenser chamber 6 kept at a lower temperature. After a few batches of preparations have thus been freeze-dried, a large quantity of ice has deposited in the condenser chamber, mainly on the outside of the heat exchanger 5.
  • the defrosting of the condenser chamber can now be effected in a simple and rapid manner a follows: the pumping device is switched off. The cock 14 is closed and the cock 16 is fully opened. The liquid which is heated to a comparatively high temperature by the heating device 17 is now circulated by the pumping device 18, along the path denoted by the broken-line arrows.
  • the warm liquid supplies its thermal energy in the heat exchanger 5 to the ice in the condenser chamber.
  • the flow of liquid during the heating process flows through the pumping device 15 and the heat exchanger 5 in a direction which is opposite to that during the cooling process. By the use of circulation pumps this is no problem.
  • the flow of liquid substantially does not flow through or does not flow at all through the heat exchanger 2. This is caused by the fact already mentioned above that the resistance to flow of the heat exchanger 2 is considerably larger than that of the heat exchanger 5 so that the flow of liquid chooses the easiest way through the last-mentioned heat exchanger. of course it is also possible to prevent the flow of liquid through the heat exchanger 2 by means of cocks incorporated in the sections of the ducts situated between the heat exchanger 2 and the points A and E.
  • the whole flow of liquid is available for the heat transport from the heating device 17 to the condenser chamber 6 which is in favor of a rapid defrosting.
  • the liquid is heated to a comparatively high temperature, as gas under pressure for example, nitrogen, present in the expansion container 19 above the liquid ensuring that the liquid does not start boiling.
  • the operating temperature of the vacuum chamber is approximately in the temperature range of from 30 to +30 C.
  • the operating temperating temperature of the condenser chamber is from 70 to -80 C.
  • the liquid when R11 is used, can be heated without boiling to 60 C. at a pressure of 2.5 atmospheres in the expansion container and the systems of ducts.
  • the pressure may vary between 1 and 1.5 atmospheres. Should, during operation, the pressure in the system of ducts increase too strongly by some cause, the valve 20 opens. Since a large flow of liquid of high temperature is conducted through the heat exchanger 5, the ice mass deposited on it is rapidly defrosted from within. In addition, said mass can be defrosted from without by conducting water of a high temperature in the condenser chamber via the inlet 6 Melting water can flow away out of the condenser chamber via the outlet 6". During the defrosting process the warm liquid does not pass the cold place of the cold-gas refrigerator, so the cold supplied by said machine is not lost. Whereas in FIG.
  • FIGS. lb and 10 show that it is also possible to use a mixing valve 21 and a distributing valve 22, respectively. For the rest the operation remains equal to that of the freeze-dryer shown in FIG. la. It will be obvious from the above that the invention provides a simple and readily operating freeze-dryer.
  • a freeze-dryer apparatus including a vacuum freezedrying chamber and a condensor chamber and vacuum pump means in communication with both chambers, and a cold-gas refrigerator for producing cold
  • the apparatus further comprising first second, and third heat-exchanger means for heat exchange respectively with said refrigerator, the condensor chamber, and the freeze-drying chamber
  • first closed duct system which includes said first and second heat exchangers and first pump means
  • second closed duct system which includes said third heat exchanger and a portion of the first duct system, second pump means, and heating means
  • li uid circulated in both of sald duct systems by sai correspon ing pump means a by-pass duct in said second duct system for bypassing said portion of the first duct system within said second duct system
  • control means for controlling liquid flow in said first and second duct systems and in said by-pass duct, whereby said circulated liquid cools said chambers and said liquid when heated in the second duct system also defrosts ice
  • a freeze-dryer according to claim 1, further comprising a liquid expansion container, in which a gaseous medium is present above the liquid under such a pressure that, at any operating temperature of the liquid, boiling of said liquid is prevented, and at least one of said duct systems communicates with said container.
  • a freeze-dryer as claimed in claim 2 in which the operating temperature of the vacuum chamber is controlled within the range of from approximately -30 C. to approximately +30 C. and the operating temperature of the condenser chamber is approximately C., characterized in that the liquid is R11 (trichlore monofluoro-metane -CCl F).

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Molecular Biology (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
US37975A 1969-05-30 1970-05-18 Freeze-dryer Expired - Lifetime US3656240A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6908334A NL6908334A (fr) 1969-05-30 1969-05-30

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US3656240A true US3656240A (en) 1972-04-18

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US37975A Expired - Lifetime US3656240A (en) 1969-05-30 1970-05-18 Freeze-dryer

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US (1) US3656240A (fr)
AT (1) AT299816B (fr)
BE (1) BE751114A (fr)
CH (1) CH507491A (fr)
DK (1) DK125214B (fr)
FR (1) FR2056214A5 (fr)
GB (1) GB1315147A (fr)
NL (1) NL6908334A (fr)
SE (1) SE351918B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909957A (en) * 1971-07-14 1975-10-07 Arjun Dev Passey Apparatus for freeze-drying
US6610250B1 (en) 1999-08-23 2003-08-26 3M Innovative Properties Company Apparatus using halogenated organic fluids for heat transfer in low temperature processes requiring sterilization and methods therefor
US20080060379A1 (en) * 2006-09-08 2008-03-13 Alan Cheng Cryogenic refrigeration system for lyophilization
WO2016150995A1 (fr) * 2015-03-26 2016-09-29 Gea Lyophil Gmbh Condenseur pourvu d'un évaporateur chauffé
CN117178156A (zh) * 2021-03-05 2023-12-05 Gea冻干制药有限责任公司 冻干机和用于操作冻干机的方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116242103A (zh) * 2022-12-23 2023-06-09 东富龙科技集团股份有限公司 一种冻干机的节能系统

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3146077A (en) * 1961-07-20 1964-08-25 Pennsalt Chemicals Corp Freeze drying apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3146077A (en) * 1961-07-20 1964-08-25 Pennsalt Chemicals Corp Freeze drying apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909957A (en) * 1971-07-14 1975-10-07 Arjun Dev Passey Apparatus for freeze-drying
US6610250B1 (en) 1999-08-23 2003-08-26 3M Innovative Properties Company Apparatus using halogenated organic fluids for heat transfer in low temperature processes requiring sterilization and methods therefor
US20080060379A1 (en) * 2006-09-08 2008-03-13 Alan Cheng Cryogenic refrigeration system for lyophilization
WO2008085208A3 (fr) * 2006-09-08 2009-02-12 Praxair Technology Inc Système de réfrigération cryogénique pour la lyophilisation
CN101140126B (zh) * 2006-09-08 2011-04-06 普莱克斯技术有限公司 用于冻干的低温制冷系统
US8015841B2 (en) 2006-09-08 2011-09-13 Praxair Technology, Inc. Cryogenic refrigeration system for lyophilization
US20110283717A1 (en) * 2006-09-08 2011-11-24 Alan Cheng Method for lyophilization using cryogenic refrigeration system
US8938979B2 (en) * 2006-09-08 2015-01-27 Praxair Technology, Inc. Method for lyophilization using cryogenic refrigeration system
WO2016150995A1 (fr) * 2015-03-26 2016-09-29 Gea Lyophil Gmbh Condenseur pourvu d'un évaporateur chauffé
CN117178156A (zh) * 2021-03-05 2023-12-05 Gea冻干制药有限责任公司 冻干机和用于操作冻干机的方法

Also Published As

Publication number Publication date
BE751114A (fr) 1970-11-30
SE351918B (fr) 1972-12-11
NL6908334A (fr) 1970-12-02
AT299816B (de) 1972-07-10
FR2056214A5 (fr) 1971-05-14
CH507491A (de) 1971-05-15
DE2025999A1 (de) 1970-12-03
GB1315147A (en) 1973-04-26
DE2025999B2 (de) 1977-04-07
DK125214B (da) 1973-01-15

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