Freeze-drying system and method therefor

Abstract

The invention relates to a freeze-drying system for drying products containing liquid and to a method for operating a freeze-drying system, said freeze-drying system having a vacuum chamber, in which at least one holding device for holding the products containing liquid is inserted, a coolable condenser being provided, on which liquid drawn from the product in a drying phase can be condensed from a vapor phase. According to the invention, at least one sound generator is arranged on the holding device, by means of which sound generator sound can be applied to the product during the drying phase.

Claims

1. A freeze-drying system for freeze-drying products containing liquid, wherein in a drying phase the products are kept at a temperature below or close to the freezing point of the liquid and exposed to a low-pressure atmosphere, so that drying by sublimation of the frozen liquid takes place, the freeze-drying system comprising: a vacuum chamber in which at least one reception device for receiving the products containing liquid is introduced; and at least one sound generator by which the products can be treated with sound during the drying phase is arranged at the reception device; wherein a coolable condenser is present at which liquid withdrawn from the products in the drying phase can be precipitated from a vapor phase; and the reception device comprises a conducting device for conducting a fluid to cool or to heat the products at the reception device, with the sound generator being arranged at the conducting device and designed to send a sound into the fluid.

2. The freeze-drying system in accordance with claim 1, wherein the reception device comprises one or more reception plates, with the products being able to be placed on an upper side of the reception plate, and with the at least one sound generator being arranged at a lower side of the reception plate disposed opposite the upper side.

3. The freeze-drying system in accordance with claim 1, wherein a reception space is formed in the vacuum chamber, with the condenser being introduced in the reception space together with the reception device and the products.

4. The freeze-drying system in accordance with claim 1, wherein the condenser is spatially formed such that is surrounds the reception device at an outer side.

5. The freeze-drying system in accordance with claim 1, wherein the reception device comprises a reception plate that is formed by a base plate of the vacuum chamber.

6. The freeze-drying system in accordance with claim 1, wherein the sound generator forms an ultrasound generator and sends a sound into the products at a sound frequency of at least 16 kHz by a solid-borne sound transfer in a reception plate of the reception device and/or via a fluid column of the fluid in a fluid line.

7. A method of freeze-drying products containing liquid using a freeze-drying system, wherein in a drying phase the products are kept at a temperature below or close to the freezing point of the liquid and exposed to a low-pressure atmosphere, so that drying by sublimation of the frozen liquid takes place, the freeze-drying system comprising: at least one sound generator arranged at a reception device for receiving the products containing liquid in a vacuum chamber and with the products being treated with sound during the drying phase by a sound wave conducting through at least a part of the reception device by the sound generator; and wherein the reception device comprises a conducting device for conducting a fluid to cool or to heat the products at the reception device, with the sound generator being arranged at the conducting device and sending a sound into the fluid so that the sound is conducted through the fluid to a reception plate of the reception device and thus to the products.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further measures improving the invention will be shown in more detail below together with the description of preferred embodiments of the invention with reference to the Figures. There are shown:

(2) FIG. 1 is a schematic view of an embodiment of a freeze-drying system in accordance with the prior art;

(3) FIG. 2 is a freeze-drying system in a schematic view having the features of the invention;

(4) FIG. 3 is a detailed view of a part of a reception apparatus with a product standing on a reception plate;

(5) FIG. 4 is a further embodiment of a freeze-drying system with an alternative embodiment of the reception apparatus;

(6) FIG. 5 is a freeze-drying system with an alternative arrangement of a sound generator; and

(7) FIG. 6 is a detailed view of a fluid line at which a sound generator is arranged.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) FIG. 1 shows a freeze-drying system 1 in accordance with the prior art and the freeze-drying system 1 has already been looked at in detail in connection with the introductory part of the present description.

(9) FIG. 2 shows a freeze-drying system 1 in accordance with a first variant of the invention and the freeze-drying system 1 has a vacuum chamber 11 and the vacuum chamber 11 forms a reception space 15 that can be evacuated. A reception apparatus 12 for receiving products 10 to be dried is received in the reception space 15. A condenser 13, that is shown schematically and that by way of example surrounds the reception apparatus 12 at the outer side, is furthermore located in the same reception space 15.

(10) The reception apparatus 12 has a plurality of reception plates 16 on which the products 10 to be dried are placed. A conducting device 19 having fluid lines 24 is connected to the reception plates 15 and a fluid 20, for example a silicone oil, can be conducted through the fluid lines 24. The fluid 20 can be cooled or heated by peripheral devices so that the products 10 can also be cooled, and in particular heated, by the heat exchange with the reception plates 16.

(11) A plurality of sound generators 14 for transmitting a sound, in particular an ultrasound, are arranged below the reception plates 16 so that the products 10 placed on the reception plates 16 can be directly treated with sound by the direct arrangement of the sound generators 14 on the reception plates 16.

(12) The vacuum chamber 11 has a vacuum connection 26 via which the vacuum chamber 11 can be evacuated or can also be vented again with the aid of further peripheral devices, not shown.

(13) If the freeze-drying system 1 is put into operation, the products 10 can first be inserted or set into the reception apparatus 12 in the frozen state or can be introduced into the vacuum chamber 11 together with the reception apparatus 12. The vacuum chamber 11 is subsequently closed and is evacuated via the vacuum connection 26. Due to the falling phase transition point of the solid phase of the liquid in the frozen product, this can change directly into the vapor state without forming a liquid phase, whereby the product dries. If the condenser 13 is flowed through by a refrigerant, for example, it can be brought to a very low freezing temperature and the liquid vapor from the sublimation process of the product 10 can precipitate directly at the surface of the condenser 13.

(14) If the sound generators 14 are operated during the drying phase of the products 10 and if the sound generators, for example, transmit ultrasound directly into the products 10, the sublimation of the liquid in the products 10 is considerably accelerated. The temperature can simultaneously be uniformly heated due to the ultrasound influence so that a heating accompanying this can take place additionally or alternatively to heating of the products 10 via a heated fluid 20.

(15) In a manner not shown, the condensers can additionally be equipped with and treated by sound generators to achieve, by the effect of the sound excitement, a higher packing density of the precipitating ice from the gas phase of the liquid since smaller ice crystals are formed.

(16) FIG. 3 shows by way of example an enlarged view of the product 10 that is placed on an upper side 17 of the reception plate 16. A sound generator 14 is arranged on the lower side 18 of the reception plate 16 and can send sound, in particular ultrasound, directly into the product 10 through the reception plate 16. The product 10 can, for example, be stored in a container and can stand on the upper side 17 of the reception plate 16. If a plurality of products 10 are placed on the reception plate 16, a plurality of sound generators 14 associated with the respective products 10 can also be arranged on the lower side 18 of the reception plate 16.

(17) FIG. 4 shows an alternative embodiment of the reception apparatus 12 and a reception plate 16 attached to a rack 29 is shown and a plurality of products 12 stand on the upper side 17 of the reception plate 16. A sound generator 14 is arranged on the lower side 18 of the reception plate 16.

(18) The example in accordance with FIG. 4 simultaneously also shows the possibility that a base plate 16′ of the vacuum chamber 11 forms the reception apparatus 12 for receiving the products 10 and the sound generator 14 is arranged at the outer side below the base plate 16′. The base plate 16′ thus forms an alternative form of the reception plate 16 and in the sense of the invention thus also a part of the reception apparatus 12.

(19) FIG. 5 represents a further embodiment of a freeze-drying system 1 with a vacuum chamber 11 in which the reception apparatus 15 is formed and the reception apparatus 12 is introduced in the reception space 15. The reception apparatus 12 in turn has a plurality of reception plates 16 and each of the reception plates 16 is connected by single lines to the conducting device 19 that comprises a plurality of fluid lines 24 through conducting the fluid 20. The condenser 13 is furthermore arranged in the vacuum chamber 11 and the vacuum chamber 11 has a vacuum connector 26 for evacuating and for venting thereof.

(20) The products 10 are disposed on the upper side of the reception plates 16, with six products being shown by way of example.

(21) In accordance with the embodiment, a sound generator 14 is arranged at a fluid line 24 and can introduce sound, in particular ultrasound, in the conducting device 19. In this respect, a conducting of the sound takes place via the fluid line itself, but in particular also via the fluid column that is conducted into the reception plates 16, see by way of example a fluid flow arrow before the second reception plate 16 on which the products 10 are placed. The possibility is thus used of introducing an ultrasound into all the reception plates 16 by a centrally arranged sound generator and the line branching of the conducting device 19, said ultrasound being able to be conducted via the line, and in particular via the liquid column, directly to the products 10 that are placed on the upper side of the reception plates 16.

(22) An alternative sound treatment point 28 can be formed, for example, in or at each of the fluid lines 24 at which one sound generator is arranged per reception plate 16.

(23) FIG. 6 shows for this purpose a detailed view of a reception plate 16 and a fluid passage 27 through which the fluid 20 is conducted and that is connected to the fluid line 24 is located in the reception plate 16. A product 10 stands on the upper side 17 of the reception plate 16 by way of example.

(24) A sound generator 14 that can send a sound, in particular an ultrasound, into the region of the fluid 20 that flows through the fluid passage 27 within the reception plate 16 is arranged by way of example at an end side of a section of the fluid line 24 extending in a straight line. The schematic view illustrates the possibility of using the fluid column of the fluid to conduct the sound to the product 10 and the fluid can simultaneously be used as a heating and cooling fluid to heat and cool the product 10.

(25) The invention is not restricted in its design to the preferred embodiment specified above. A number of variants is rather conceivable that also makes use of the solution shown with a generally differently designed embodiment. All the features and/or advantages, including any construction details or spatial arrangements, originating from the claims, the description or the drawings can be essential to the invention both per se and in the most varied combinations.

REFERENCE NUMERAL LIST

(26) 1 freeze-drying system 10 product 11 vacuum chamber 12 reception device 13 condenser 14 sound generator 15 reception space 16 reception plate 16′ base plate 17 upper side 18 lower side 19 conducting device 20 fluid 21 intermediate wall 22 valve 23 refrigerant 24 fluid line 25 condenser chamber 26 vacuum connection 27 fluid passage 28 sound treatment point 29 rack