US3740860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Freeze drying method and apparatus
Assignee: SMITHERM IND INC US
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Filing: 1972-07-31
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Granted: 1973-06-26
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Expires: 1992-07-31
Abstract
Abstract Freeze drying methods and apparatus in which a product is frozen onto a conveyor in a vacuum vessel compartment in which the pressure is high enough to keep volatiles from evolving from the product. The product is then conveyed through a drying compartment maintained at a lower pressure where heat is applied to the product to evolve moisture from it. Thereafter, the dried product is removed from the conveyor and the vacuum vessel.
Inventors
- 👤 H Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:16
CPC Classifications
F; F26; F26B; F26B5/00; F26B5/04; F26B5/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
151 words
Freeze drying apparatus comprising: a vacuum vessel; means dividing said vacuum vessel into a freezing compartment and a drying compartment; means for evacuating said vessel; means for conveying a product to be dried from said freezing compartment into and through said drying compartment; means for introducing a liquid or semiliquid product to be dried into the freezing compartment and onto the conveying means in a layer, means for cooling said conveying means to freeze the product thereto; means for keeping the pressure in the freezing compartment at a selected level which is sufficiently high to prevent volatiles from evolving from the product until it is frozen to the conveying means and to prevent the product from freezing until it is on the conveying means; means for heating the product as it is conveyed through the drying compartment to evolve water therefrom; and means for removing the dried product from the vessel.
Claim 2
Dependent Claim
151 words
Freeze drying apparatus comprising: a vacuum vessel; means dividing said vacuum vessel into a freezing compartment and a drying compartment; means for evacuating said vessel; means for conveying a product to be dried from said freezing compartment into and through said drying compartment; means for introducing a liquid or semiliquid product to be dried into the freezing compartment and onto the conveying means in a layer, means for cooling said conveying means to freeze the product thereto; means for keeping the pressure in the freezing compartment at a selected level which is sufficiently high to prevent volatiles from evolving from the product until it is frozen to the conveying means and to prevent the product from freezing until it is on the conveying means; means for heating the product as it is conveyed through the drying compartment to evolve water therefrom; and means for removing the dried product from the vessel.
Claim 3
Dependent Claim
58 words
The freeze drying apparatus of claim 1, wherein the means for providing water vapor in said freezing compartment comprises a receptacle in said freezing compartment, means for supplying water to said receptacle, and means for maintaining the water in said receptacle at a temperature sufficiently high that said water will volatilize at the pressure in the freezing compartment.
Claim 4
Dependent Claim
33 words
The freeze drying appartus of claim 1, wherein the means for cooling the product conveying means comprises means for effecting the flow of a refrigerant into heat exchange relationship with said conveyor means.
Claim 5
Dependent Claim
62 words
Freeze drying apparatus according to claim 1, wherein the product conveying means has a material bearing leg and wherein the means for cooling said conveying means comprises a reservoir beneath said material bearing leg and means for effecting a flow of said coolant into said reservoir and out the upper end thereof and into heat transfer relationship with said material bearing leg.
Claim 6
Dependent Claim
35 words
The freeze drying apparatus of claim 1, wherein the means for maintaining the pressure in the freezing compartment at the selected level is means for maintaining an atmosphere of water vapor in said freezing compartment.
Claim 7
Dependent Claim
75 words
The freeze drying apparatus of claim 5, wherein there is a partition in said vacuum vessel dividing it into said freezing and drying compartments, there being apertures in said partition through which said conveyor can pass and said apparatus further including means for removing from said vacuum vessel moisture evolved from the product in the drying compartment and water vapor flowing from the freezing compartment into the drying compartment through the apertures in the partition.
Claim 8
Independent Claim
87 words
The method of freeze drying a product, comprising the steps of: introducing the product to be dried into a zone maintained at a pressure which is below atmospheric but is sufficiently high to keep volatile constituents of said product from vaporizing; spreading the product into a layer; freezing the product in said layer; reducing the pressure on the frozen product to a pressure below 4.6 mm of mercury; and heating the product to effect the sublimation of water from the product and thereby reduce its moisture content.
Claim 9
Independent Claim
87 words
The method of freeze drying a product, comprising the steps of: introducing the product to be dried into a zone maintained at a pressure which is below atmospheric but is sufficiently high to keep volatile constituents of said product from vaporizing; spreading the product into a layer; freezing the product in said layer; reducing the pressure on the frozen product to a pressure below 4.6 mm of mercury; and heating the product to effect the sublimation of water from the product and thereby reduce its moisture content.
Claim 10
Dependent Claim
21 words
The method of claim 7, wherein said product is spread into a layer which is not more than one-sixteenth inch thick.
Claim 11
Dependent Claim
22 words
The method of claim 7, wherein the selected pressure in said zone is obtained by maintaining therein an atmosphere of evaporated water.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |