CONTINUOUS FREEZE DRYER

• US 3,731,392 A
• Filed: 02/25/1971
• Issued: 05/08/1973
• Est. Priority Date: 02/25/1971
• Status: Expired due to Term

• Current Assignee: Herbert Gottfried
• Original Assignee: Herbert Gottfried
• Inventors: Gottfried, Herbert
• Primary Examiner(s): O'Dea, William F.
• Assistant Examiner(s): Anderson, William C.
• Application Number:
  US05/118,934
• Time in Patent Office: 803 Days
• Field of Search: 34/5,192
• US Class Current: 34/291
• CPC Class Codes: A23L 2/14 and sublimation
• CPC Class Codes: A23L 3/44 Freeze-drying
• CPC Class Codes: F26B 5/06 the process involving freezing

Abstract

Arrangement for continuously and automatically lyophilizing material comprising freezing the material, pulverizing the frozen material, circulating the material along a screw conveyor while exhausting the ambient gas to heat the material and expose particles of material to heat, regulating the heat supplied by reversible refrigeration, alternately exhausting said ambient gas in first and second cold traps, sequentially finishing partially treated material in at least first and second finishing zones and discharging the material into containers without breaking the vacuum.

Claims

1. The method of continuously and automatically lyophilizing material comprising the steps of:

a. freezing the material;

b. pulverizing the frozen material;

c. circulating the material from an inlet zone along a screw conveyor while exhausting the ambient gas to heat the material and exposing particles of material to heat and recycling the material back to the inlet zone;

d. regulating the heat supplied by the rate of rotation of the circulating screw and by reversible refrigeration;

e. alternately exhausting said ambient gas in first and second cold traps;

f. sequentially finishing partially treated material in at least first and second finishing zones; and

, g. discharging the material into containers without breaking the vacuum.

2. In an automatic and continuous freeze drying instrument, in combination, a. input means to introduce under vacuum a material to be processed in the instrument;

b. an elongated lyophilization chamber, connected to said input means, said chamber having screw conveyor means therein for conveying and agitating said material longitudinally in said chamber to one end thereof, including means for adjustably rotating said screw conveyor means at predetermined speeds, said rotation also supplying heat to the chamber and means for controlling said adjustable rotating means for controlling the temperature in the chamber;

c. a return path coupled to said chamber for guiding material from said one end to the other end of said chamber;

d. reversible refrigeration means to cool or heat said chamber and thus maintain the wall temperature within a predetermined range;

e. a vacuum pump and cold trap arrangement to constantly evacuate gas formed by moisture in said chamber; and

, f. vacuum discharge means to discharge treated material from the chamber while maintaining the vacuum in the chamber.

3. A device for the continuous dehydration of materials which are sensitive to heat which comprises, a. a conveyor to continuously feed said material to be dehydrated to a first freezing and crushing compartment;

b. a reversible first refrigeration unit attached to said freezing and crushing compartment;

said freezing and crushing compartment having means for pulverizing the frozen material, said first refrigeration unit supplying a constant reduced temperature to said freezing compartment so as to freeze and maintain the material in a frozen statE;

c. a lyophilizing and constant movement zone connected to said freezing and crushing compartment;

said lyophilizing zone being attached to a condensing zone;

said condensing zone being maintained at a low temperature by a second reversible refrigeration unit so as to condense the moisture removed from the material being dehydrated;

d. a vacuum pump attached to said condensing zone so as to maintain a reduced pressure causing the material in the lyophilizing zone to give up its water and cool itself, thus remaining in a frozen state;

e. a third reversible refrigeration unit attached to said lyophilizing and constant movement zone so as to maintain a flow of heat to the material being dehydrated so as to supply energy required for lyophilization;

f. means for continuously agitating progressively advancing and recycling the material in the lyophilizing and constant movement zone; and

, g. a receiving and packaging zone attached to said lyophilizing and constant movement zone so that the material can be removed from the lyophilizing and constant movement zone without breaking the vacuum in the major portion of said zone in order for the material to be removed and packaged in a continuous mode;

h. and means for adjusting said continuously agitating means at predetermined speeds, said continuously agitating means also supplying heat to the lyophilizing and constant movement zone; and

means for controlling said adjusting means for controlling the temperature in the lyophilizing and constant movement zone for controlling the temperature in the zone.

4. In a freeze drying instrument, in combination, a. input means to introduce under vacuum a material to be processed in the instrument;

b. an elongated lyophilization chamber, connected to said input means, said chamber having agitation conveyor means therein for conveying said material longitudinally in said chamber to one end thereof at predetermined speeds, means for adjusting said agitation conveyor means at predetermined speeds, said agitation exposing all parts of said material to treatment and heating said material, and means for controlling said adjusting means for controlling the temperature in the chamber, c. a return path coupled to said chamber for guiding material from said one end to the other end of said chamber;

d. refrigeration means to cool or heat said chamber and thus maintain the wall temperature within a predetermined range;

e. a vacuum pump and cold trap arrangement to constantly evacuate gas formed by moisture in said chamber; and

, f. vacuum discharge means to discharge treated material from the chamber while maintaining a vacuum in said chamber.

5. An instrument as claimed in claim 4, wherein said refrigeration means are reversible.

6. An instrument as claimed in claim 4, including a. in said input means, constant leveling means and a cooled pipe (14) connected to a freezing zone (16);

and, b. said freezing zone comprising an elongated chamber having a screw conveyor therein and refrigeration means to heat and cool said freezing zone.

7. An instrument as claimed in claim 4, wherein said lyophilization chamber is generally vertically inclined, said agitation means is a central screw conveyor and said return path is a chute from the top of said chamber to the bottom thereof on the outer side of said chamber, said material being carried upward by the screw conveyor and carried downwards by said chute.

8. An instrument as claimed in claim 4, wherein said lyophilization chamber is substantially horizontal including first and second screw conveyors for conveying material in opposite directions, with a partition wall therebetween.

9. An instrument as claimed in claim 4, wherein said lyophilization chamber is generally vertically inclined, said agitation means is a central screw conveyor in said lyophilization chamber and said return path includes a cylindrical partition in said chamber.

10. An instrument as claimed in claim 9, includiNg an outer screw conveyor with a few convolutions around said partition.

11. An instrument as claimed in claim 4, including at least first and second finishing chambers connected to said lyophilization chamber, said finishing chambers being constructed similar to said lyophilization chambers and being coupled to said vacuum discharge means, the material being first partially lyophilized in said lyophilization chamber until ambient pressure in said lyophilization chamber reaches a predetermined level and then transferred to said finishing chamber when all remaining moisture is removed.

12. An instrument as claimed in claim 10, including means for automatically transferring material between chambers under vacuum.