US3590496A - Insert for freeze-drying apparatus - Google Patents

Abstract

An insertable container for freeze-drying apparatus having a water-vapor-permeable channel member which forms a venting channel with respect to the surface of the material being dried. The channel member is in the form of a partition which extends along a horizontal dimension of the container within the fill area thereof. By this arrangement, water vapor can be drawn off from the material being dried by way of the partition. Numerous specific forms of the partition are described as well as several arrangements of the partition with respect to the container itself.

Description

United States Patent [72] Inventor Hanns Ellenberg Rosrath. Germany [2!] Appl. No 750,872

[22] Filed Aug. 7, 1968 July 6, 1971 Leybold-Heraeus-Verwaltung G.m.b.ll. Cologne-Bayental, Germany [45] Patented [73] Assignee [32] Priority Aug. 23,1967 [33] Germany [31] L 57276 [54] INSERT FOR FREEZE-DRYING APPARATUS 6 Claims, 10 Drawing Figs. [52] U.S. Cl 34/238 [51] lnt.Cl F26b 25/10 [50] Field of Search 34/9, 92,

[56] References Cited UNITED STATES PATENTS 1,149,948 8/1915 Rand 34/78 1.349.458 8/1920 Johnson 34/238 3.258.854 1966 Ascoll et al 34/237 3.401.468 9/l968 Eilenberg et al 34/237 FOREIGN PATENTS l.l35,83l 8/1962 Germany 237/239 922.493 Great Britain 34/5 Primary Examiner Frederick L Matteson Assistant Examiner-Harry B. Ramey Attorney-Spencer and Kaye ABSTRACT: An insertable container for freeze-drying apparatus having a water-vapor-permeable channel member which forms a venting channel with respect to the surface of the material being dried. The channel. member is in the form of a partition which extends along a horizontal dimension of the container within the fill area thereof. By this arrangement, water vapor can be drawn off from the material being dried by way of the partition. Numerous specific forms of the partition are described as well as several arrangements of the partition with respect to the container itself.

PATENTEU JUL 6 IQTI SHEET 1 OF 4 INVENTOR Honns Eilenberg ATTORNEYS PATENTEDJUL 6l97| 3,590,496

SHEET 2 BF 4 Fig. 4

INVENTOR Honnls Eilen berg ATTORNEYS PATENTED JUL 6 :91:

SHEET 3 OF 4 Fig. 7

INVENTOR Hunns Eilenberg BY W ATTORNEYS PATENTEBJUL Bran 3.590.498

SHEET 4 UF 4 F l'g. l0

INVENTOR Hcmns Eilen berg BY WZAM ATTORNEYS llhlfiElilT I 'OII I IItIEIEZE-IDIRYING APPARATUS CROSS-REFERENCE TO RELATED APPLICATIONS The present invention is an improvement of the inventions described in application Ser. No. 619,689, filed Mar. lst, 1967, and application Ser. No. 715,035, filed Mar. 21st, 1968.

BACKGROUND Oi THE INVENTION The present invention relates to an insertable container for use in freeze-drying apparatus and, more particularly, to such a container having at least one water-vaporpermeable chan' nel member which forms at least one venting channel with respect to the surface of the material, contained by such container, to be dried.

The present invention is concerned with the freeze-drying of granulated or particulate materials. Very generally, freezedrying such materials involves converting all of the moisture contained in the material to ice, then applying heat to the product in an atmosphere of reduced pressure to vaporize or sublime the ice and thereby remove it from the material. From the standpoint of the efficiency of the freeze-drying process, it is desirable to effect the removal of the moisture from the product in the shortest possible time.

One disadvantage in removing moisture from the material being freeze-dried by vaporization is that the material in the tray forms a bed which obstructs the flow of vapor therefrom. The degree to which the material serves as an obstacle to the flow of vapor is, of course, dependent on the form and size of the granules of the material and the distance through which the vapor must flow through the material. Therefore, containers which hold such materials must be provided with means for assisting the drawing off of water vapor to thereby facilitate the drying process. Two such means are disclosed in the two US. applications referred to above. The basic concept of each of these previous inventions is to provide exposure to as much of the surface material being dried as possible. The present invention also relies on this concept and improves upon the prior inventions by defining better means for accomplishing this result.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an improved, relatively simple and yet more effective means for facilitating the drying of bulk materials in a freeze-drying container than, heretofore, available in the art.

It is also an object of this invention to provide an even better means for drawing water vapor off from granulated bulk materials being freeze-dried.

In brief, the present invention contemplates the use of a water-vapor-permeable channel member provided in an insertable container for freeze-drying apparatus. Such channel member is designed to provide a venting channel with respect to the surface of the material being dried in such container. The channel member is in the form of a partition disposed in the fill area of the container and extends along the entire length ofa given horizontal inner surface of the container.

The invention contemplates various forms of such a partition including one having a wedge-shaped cross section at least in its portion near the bottom surface of the container with the narrower end of the wedge-shaped cross section directed toward such bottom.

In another form, the partition is arranged with respect to intermediate wall members provided in the fill area of the container to form venting channels therewith.

In another form of the invention, the partition includes a corrugated external surface.

In still another form, the invention contemplates the use of a partition formed by two walls wherein slit-type openings are provided and the partition, moreover, is permanently connected to the inner surface of the container.

In yet another form of the present invention, the partition is formed from a good heat-conducting material and is in good heat conductive contact with the inner wall surfaces of the container. Thus, in addition to drawing vapor from the material being dried, heat is transferred to the material thereby facilitating the drying process.

Moreover, the present invention proposes to provide a support means including an element which extends along the inner surface length of the container. Such element is watervapor-permeable and serves as a venting channel for water vapor drawn from the drying material. More particularly, the venting channel has a wedge-shaped cross section with the narrower end portion of the wedge-shaped cross section resting on the bottom of the container and the wider portion of the wedge-shaped cross section extending vertically at least to the level of the upper surface of the material being dried. By this arrangement, the venting element is positioned within the material being dried in such a manner that openings in the venting channel can, advantageously, be placed at that level where the ice-containing core of the material being dried is disposed. Moreover, the wedge-shaped configuration of the venting channel, advantageously, provides a means for reaching water vapors trapped in the reaches of the material being dried above the container bottom. The sloping sides of the venting channel facilitate the collecting of vapor from the relatively thick bulk material at the bottom of the container and provide an effective means or channel whereby water vapor is drawn from the material being dried. The angle between the sides of the wedge-shaped venting channel can be relatively narrow so as not to occupy too much of the volume of the container.

The venting channel, or partition, of the present invention is formed of a perforated or sievelilce material with good heatconducting properties. The use of suitable sintered, screened or spongelike materials is also possible. The particular material which forms the partition or venting channel depends on the relative capacity of such material to draw offwater vapor from the bulk material when compared with sievelike materials.

In yet another form, the present invention provides that the venting channel is constructed as a separable element so that it may be removed as a unit from the container, as desired. It has been found advantageous to provide intermediate wall members within a container to form separated portions or subdivisions within the fill area of the container and a venting channel within each such portion; venting channels in adjacent portions being separably connected to one another.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a longitudinal, sectional view taken generally along line 1-1 of FIG. 3, showing an insertable container having a venting channel according to the present invention.

FIG. 2 is a schematic and perspective view of the container, as shown in FIG. I, wherein a plurality of venting channels according to the present invention are illustrated.

FIG. 3 is a cross-sectional view taken generally along the line defined by reference line 3-3 of FIG. ll.

FIG. 4i is a crosssectional view corresponding to the view of FIG. 3 and showing a plurality of insertable venting channels.

FIG. 5 is a cross-sectional view corresponding to FIG. 3 in which the venting channels extend longitudinally and have a cross section with a wedge-shaped portion.

FIG. 6 is a cross-sectional view corresponding to that of FIG. 3 in which the venting channels are longitudinally extending partitions permanently connected to the container.

FIG. '7 is a cross-sectional view corresponding to that of FIG. 3 in which the venting channels extend over intermediate wall members of the container to define vapor escape channels therewith.

FIG. I} is a schematic perspective view of an insertable container wherein the venting channel is formed by a partition having a corrugated exterior wall surface.

FIG. 9 is a cross-sectional view corresponding to that of FIG. 3 in which the venting channels are provided with slittype openings and are permanently connected to the contamer.

FIG. is a partial schematic perspective view of the insertable container according to the form of the invention shown in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, a longitudinal section of a generally rectangularly shaped insertable container 1 is shown therein. The container 1 includes intermediate wall members 2, 3 and 4 (FIGS. 2 and 3) which are parallel with respect to each other and form a plurality of parallel fill areas 5, 6, 7 and 8 (FIG. 3). Each fill area contains a venting channel in the form of partitions 9, 10, 11 and 12. Both the wall members and the venting channels serve as supporting means for the granulated bulk materials introduced into the container 1 for freeze-drying. The partitions 9, 10, 11 and 12 are preferably formed of sheet metal and include perforations 31 for venting vapor therethrough. The venting partitions 9, 10, 11 and 12 thus'serve to draw off water vapor from the material being dried. The partition venting channels can be supported in the fill areas by different means provided therefor in conjunction with the inner surfaces of container 1.

Referring to FIG. 3, as shown therein, the venting channels, partitions 9, I0, 11 and 12, are centrally and symmetrically disposed in the spaces defined between intermediate wall members 2, 3 and 4. The partitions 9, l0, l1 and 12 are wedge-shaped in cross section and include a narrow end 32 which extends along the bottom of the container and a wider end 33 which extends above the material filled in the container 1.

Referring to FIG. 2, the partitions 9, 10, 1 1 and 12 are connected to each other by spacers 34, provided therefor. While spacers 34 are shown, the partition venting channels can be be supported in the fill areas by other means provided therefor, in conjunction with the inner surfaces of container 1. The partitions 9, 10, 11 and 12 are removably assembled in the container 1. The spacers 34 serve to hold or support the partitions 9, 10, 11 and 12 in position particularly when the material being dried is poured into container 1. The spacers 34, moreover, are inserted into indentations (see FIG. 3) which are cut out of the elements 9, 10, 11 and 12 in such a manner that the venting assembly, thus formed, is under spring load.

Referring to FIG. 4, venting channels, for example, partitions 13 and 14, are provided with clamping means in the form of outwardly bent end portions 35. The partitions 13 and 14 are supported by the bent end portions 35 in the area of each subdivision of the fill area. The bent end portions are formed of a material which is heat conductive and the outwardly bent end portions 35 of each partition are in good heat conductive contact with the base of the container 1. Thus, additional heating of the materials introduced into the container 1 is achieved by way of the venting channels themselves and heat lost during the sublimation of the ice formed in the bulk material is compensated for. The clamping means are releasable, thus allowing the partitions 13 and 14 to be removed from the container 1 as desired. By providing a heat conductive surface portion of a partition along at least one interior surface of the insertable container 1, the freeze-drying process, as a whole, is made more economical.

Referring to FIG. 5, the partitions I5 and 16, there shown, are provided wedge-shaped cross sections only in the lower portion or that portion near the bottom of the container. By this arrangement, less space is occupied by the partitions in the fill area and, therefore, additional materials can be introduced into the container 1 under the same water vapor conditions. The narrower end of the wedge-shaped cross section of the partitions in this form of the invention is directed toward the bottom of the container 1.

Referring next to FIG. 6, partitions 17, 18 and 19 which form intermediate walls are shown in the insertable container 1, subdividing the same into fill areas. Each of the partitions shown in FIG. 6 are permanently connected to the bottom of the container 1, for example, by soldering. Thus, a good heat conductive contact with the bottom of the container 1 is assured.

Referring to FIG. 7, the partitions 20, 21 and 22 are illustrated therein. These partitions are provided on an insert 36 which is provided with perforations and which is inserted into the container 1 and pressed to the bottom surface of container 1. The partitions 20, 21 and 22 are spaced from the intermediate wall members and container sidewalls, thus forming a space between such walls and the partitions. Moreover, the partitions are connected to extend over the intermediate sidewalls. The space thus defined provides a venting space in which vapors from the materials being freeze-dried are collected.

Referring to FIG. 8, in this form of the invention partitions, for example, 23 and 24 having corrugated exterior surfaces are provided. In the FIG. 8 embodiment of the invention, two corrugated surfaces or walls are provided and a plurality of pocket-type venting spaces or channels 37 which extend perpendicularly with respect to the bottom of container 1 are provided between these walls. The venting channels thus formed provide a considerable improvement in the gas and water vapor exchange within the container, during the freeze-drying process. The corrugated surface can be zigzag-shaped or in another form the corrugated surface of the partition can be sinusoidal-shaped.

Referring to FIG. 9, partitions 25, 26 and 27 are shown. These partitions are similar to those shown in FIG. 6 in that they are permanently connected to the bottom of container 1 by a metallic bond. However, the partitions 25, 26 and 27 unlike the FIG. 6 embodiment are double-walled and are provided with slit-type openings 28 positioned opposite louvered covers 29, which serve to direct gas or water vapor into the interior of channel members 25, 26 and 27 while they reduce the chances of the undesirable entry of the material being freeze-dried into the space defined between the double-walls of the partition. As previously mentioned, the permanently connected partitions 25, 26 and 27 provide excellent heat conduction and the advantages flowing therefrom are realized by the drying process.

Referring to FIG. 10, recesses 30 are provided in the end wall members of insertable container 1. The recesses 30 form a connection between the ambient atmosphere in the vacuum chamber of the freeze-drying apparatus and the space defined within the partitions 25, 26 and 27. Thus, the recesses 30 provide a means for venting or carrying away the gases collected in the interior space of partitions 25, 26 and 27, respectively.

As discussed above, it is preferred that the water-vaporpermeable partition or venting channel be made of perforated metallic material or, in lieu thereof, of synthetics. Forming the partition of a good heat-conducting material and arranging the partition in good heat-conductive relationship with at least one interior surface of the insertable container provides a distinct advantage in this type of equipment. Regarding the particular measurements of the partition, this, of course, is a consideration related to the conditions and particular freezedrying process to be performed.

The water-vapor-permeable partition should be formed of a sievelike perforated material. The partition can also be formed from sintered, screened or spongelike materials provided the particular materials used are as effective as the preferred sievelike or perforated materials.

The partitions according to the present invention provide a good gas exchange relationship between portions of the material being freeze-dried. This is especially true where the partition is in the form of a double-walled member. Such a partition can advantageously extend over the entire free longitudinal or lateral dimensions of the insertable container. Further, it is possible to dispose individual partition sections for each bed of material being dried. Such sections create channels through which gases and vapors can be extracted after the material is poured or filled into the container. The

partition can be arranged either parallel or nonparallel to walls of the container. It is, however, preferred to distribute the partitions or venting channels as uniformly and symmetrically as possible, while at the same time avoiding the unnecessary occupying of space which could otherwise be filled with materials being freeze-dried. 7

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations.

I claim:

1. In an insertable container defined by a plurality of imperforate wall members for freeze-drying apparatus at least one water-vapor-permeable channel member. which forms at least one venting channel with respect to the surface of the material to be dried, such channel member being in the form of a partition disposed in a respective one of a plurality of fill areas of the container defined by at least a part of said plurality of wall members and extending along the entire length of a given horizontal dimension thereof, the improvement wherein said container is rectangularly shaped and said imperforate wall members are long sidewalls, at least one intermediate long wall, end walls and a bottom wall, and said partition is oriented perpendicular to and the legs of the channel are arranged on said imperforate bottom wall of said container within its fill area parallel and in spaced apart relationship with respect to the respective long wall members which at least partially define the fill area to form a venting channel therewith.

2. An insertable container as defined in claim 1 wherein said partition has two parallel drying surfaces.

3. An insertable container as defined in claim 2 further including releasable clamping means for removably mounting said partition within said container, said clamping means being in heat conductive contact with the bottom surface of said container.

4. In an insertable container for freeze-drying apparatus having a bottom and side surfaces and a water-vapor-permeable channel member which forms at least one venting channel with respect to the surface of the material to be dried, such channel member being in the form of a partition having a wedge-shaped cross section at least in its portion nearest the bottom of said container and disposed in the fill area of the container and extending along the entire length of a given horizontal dimension thereof with the narrower end of said wedge-shaped cross section directed toward the bottom of said container, the improvement comprising releasable clamping means for removably mounting said partition within said container, said clamping means being in heat conductive contact with the bottom surface of said container.

5. An insertable container as defined in claim 4 wherein said partition is formed from a material having good heat conductive properties and is in heat conductive contact with an inner surface of the container.

6. An insertable container as defined in claim 5 wherein said container is rectangularly shaped and is provided with at least one intermediate wall member thereby to form a plurality of parallel fill areas and at least one partition is disposed within each of said fill areas, symmetrically with respect to said wall member.

Claims (6)

1. In an insertable container defined by a plurality of imperforate wall members for freeze-drying apparatus at least one water-vapor-permeable channel member which forms at least one venting channel with respect to the surface of the material to be dried, such channel member being in the form of a partition disposed in a respective one of a plurality of fill areas of the container defined by at least a part of said plurality of wall members and extending along the entire length of a given horizontal dimension thereof, the improvement wherein said container is rectangularly shaped and said imperforate wall members are long sidewalls, at least one intermediate long wall, end walls and a bottom wall, and said partition is oriented perpendicular to and the legs of the channel are arranged on said imperforate bottom wall of said container within its fill area parallel and in spaced apart relationship with respect to the respective long wall members which at least partially define the fill area to form a venting channel therewith.

2. An insertable container as defined in claim 1 wherein said partition has two parallel drying surfaces.

3. An insertable container as defined in claim 2 further including releasable clamping means for removably mounting said partition within said container, said clamping means being in heat conductive contact with the bottom surface of said container.

4. In an insertable container for freeze-drying apparatus having a bottom and side surfaces and a water-vapor-permeable channel member which forms at least one venting channel with respect to the surface of the material to be dried, such channel member being in the form of a partition having a wedge-shaped cross section at least in its portion nearest the bottom of said container and disposed in the fill area of the container and extending along the entire length of a given horizontal dimension thereof with the narrower end of said wedge-shaped cross section directed toward the bottom of said container, the improvement comprising releasablE clamping means for removably mounting said partition within said container, said clamping means being in heat conductive contact with the bottom surface of said container.

5. An insertable container as defined in claim 4 wherein said partition is formed from a material having good heat conductive properties and is in heat conductive contact with an inner surface of the container.

6. An insertable container as defined in claim 5 wherein said container is rectangularly shaped and is provided with at least one intermediate wall member thereby to form a plurality of parallel fill areas and at least one partition is disposed within each of said fill areas, symmetrically with respect to said wall member.

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