Bulk freeze drying using spray freezing and stirred drying

• US 9,052,138 B2
• Filed: 08/04/2010
• Issued: 06/09/2015
• Est. Priority Date: 08/04/2010
• Status: Active Grant

• Current Assignee: IMA LIFE North America Inc.
• Original Assignee: IMA LIFE North America Inc.
• Inventors: DeMarco, Francis W., Renzi, Ernesto
• Primary Examiner(s): GRAVINI, STEPHEN MICHAEL
• Application Number:
  US13/811,937
• Publication Number:
  US 20130118026A1
• Time in Patent Office: 1,770 Days
• Field of Search: 342/84, 342/87, 342/89, 343/80, 343/81, 34/92, 62/64, 625/34, 625/40, 424/464, 424/468, 424/488
• US Class Current: 1/1
• CPC Class Codes: F26B 5/065 the product to be freeze-dried being sprayed, dispersed or pulverised

Abstract

A freeze dryer processes bulk powder products. The freeze dryer freezes the product by mixing an atomized spray of product with sterile liquid nitrogen. The resultant powder is freeze dried in a vessel, and the vessel contents is agitated to maintain product contact with heated vessel wall and to prevent agglomeration.

Claims

1. A freeze drying system for freeze drying bulk product by removing a liquid, comprising:

a freeze drying chamber for containing product during the freeze drying process;

at least one bulk product spray nozzle connected to a source of the bulk product, the at least one bulk product spray nozzle being directed to an interior of the freeze drying chamber for spraying the bulk product into the freeze drying chamber;

at least one freezing agent spray nozzle connected to a source of a freezing agent, the at least one freezing agent spray nozzle being directed to the interior of the freeze drying chamber for spraying the freezing agent into the freeze drying chamber, the at least one bulk product spray nozzle and the at least one freezing agent spray nozzle being further directed to comingle respective sprays in the interior of the freeze drying chamber to create a spray-frozen product;

a mechanical agitating mechanism in a lower portion of the freeze drying chamber for agitating spray-frozen product accumulated in the lower portion of the chamber to move particles of the product into contact with walls of the freeze drying chamber;

a heater for heating at least lower walls of the freeze drying chamber;

a condensing chamber in communication with the freeze drying chamber and comprising surfaces for condensing a vapor from exhaust gas received from the freezer drying chamber;

a vacuum pump in communication with the condensing chamber; and

a controller comprising memory storing a program that, when executed by the controller, causes the freeze drying system to perform;

an aseptic spray freezing cycle wherein bulk product is sprayed from the at least one bulk product nozzle in the freeze drying chamber and a freezing agent is sprayed from the at least one freezing agent spray nozzle in the freeze drying chamber, to produce a spray frozen powder in the freeze drying chamber; and

an aseptic vacuum freeze drying cycle wherein the vacuum pump evacuates the condensing chamber and the freeze drying chamber, the heater heats the lower walls of the freeze drying chamber and the rotary mechanical agitating mechanism is rotated to dry the spray frozen powder.

2. The system of claim 1, further comprising:

a sterilant introducing means for introducing a sterilant into the freeze drying chamber.

3. The system of claim 2, wherein the sterilant is selected from the group consisting of steam and vaporized hydrogen peroxide.

4. The system of claim 1, wherein the agitating mechanism comprises a rotationally driven agitator.

5. The system of claim 1, wherein the rotationally driven agitator is driven by a drive shaft passing through the chamber wall.

6. The system of claim 1, wherein the rotationally driven agitator is driven magnetically from outside the chamber wall.

7. The system of claim 1, wherein the agitating mechanism is a vibrating mechanism externally mounted to the chamber wall.

8. The system of claim 1, wherein the agitating mechanism is a vibrating mechanism mounted to a supporting leg of the freeze drying chamber.

9. The system of claim 1, wherein the freezing agent is sterile liquid nitrogen.

10. The system of claim 1, wherein a lower portion of the freeze drying chamber is conical in shape.

11. The system of claim 1, wherein the heater is an electrical heater.

12. The system of claim 1, wherein the heater is a jacket for circulating a heated fluid.

13. The system of claim 1, further comprising

a jacket attached to the freezer drying chamber for circulating a cooled fluid for cooling the chamber during spraying;

and

a heat exchanger for cooling the cooled fluid using gas vented from the source of the freezing agent.

29. The system of claim 1, wherein the at least one bulk product spray nozzle and the at least one freezing agent spray nozzle are recessed in a wall of the freeze drying chamber to clear the mechanical agitating mechanism.

30. The system of claim 1, wherein the mechanical agitating mechanism is configured to provide a clearance for the at least one bulk product spray nozzle and the at least one freezing agent spray nozzle.

14. A freeze drying system for freeze drying bulk product by removing a liquid, comprising:

a freezing chamber for containing product during the freezing process;

a plurality of spray nozzles configured for comingling sprays of the bulk product and a freezing agent inside the freezing chamber to produce a bulk spray-frozen product powder;

a plurality of drying chambers;

a plurality of selectively closeable conduits connecting the freezing chamber with the drying chambers, the conduits being configured to transfer the bulk spray-frozen product powder without using trays and shelves;

each drying chamber comprising;

an agitating mechanism in a lower portion of the drying chamber for agitating spray frozen product powder in the lower portion of the chamber; and

a heater for heating at least lower walls of the drying chamber;

at least one condensing chamber, each one of the plurality of drying chambers being in communication with at least one of the condensing chambers, the condensing chambers comprising surfaces for condensing a vapor from exhaust gas received from the drying chambers; and

a vacuum pump in selective communication with the drying chambers and the condensing chamber.

15. The system of claim 14, further comprising:

control means for operating the selectively closeable conduits to direct the spray-frozen product powder into a first chamber of the plurality of drying chambers while simultaneously operating a second chamber of the drying chambers by evacuating the second chamber with the vacuum pump and heating the lower walls of the second chamber with the heater.

16. The system of claim 14, wherein a first drying chamber is in selective communication with first and second condensing chambers, whereby one of the first and second condensing chambers is operated to condense the solvent vapor while condensed solvent is removed from another of the chambers.

17. The system of claim 14, further comprising:

a sterilant introducing means for introducing a sterilant into at least the freezing chamber and the drying chambers.

18. The system of claim 17, wherein the sterilant is selected from the group consisting of steam and vaporized hydrogen peroxide.

19. The system of claim 14, wherein the freezing agent is sterile liquid nitrogen.

20. The system of claim 14, wherein lower portions of the drying chambers are conical.

21. A method for freeze drying a bulk product containing a liquid, comprising:

spraying the bulk product into a freezing vessel;

spraying a freezing agent into the freezing vessel, the freezing vessel being at a first pressure;

the freezing agent intermingling with the sprayed bulk product to freeze the liquid contained in the bulk product to form a frozen powder before the product drops to a lower portion of the freezing vessel;

without transferring the frozen powder, subjecting the freezing vessel to a vacuum pressure lower than the first pressure;

agitating the frozen powder under vacuum using the mechanical agitating mechanism;

after subjecting the freezing vessel to the vacuum pressure, heating the frozen powder to cause sublimation of frozen liquid in the bulk product to form a freeze dried product; and

returning the freeze dried product to atmospheric pressure.

22. The method of claim 21, wherein agitating the frozen powder under vacuum and heating the frozen powder are performed in the freezing vessel.

23. The method of claim 21, wherein the freezing agent is sterile liquid nitrogen.

24. The method of claim 21, wherein the bulk product and the freezing agent are sprayed from separate nozzles into the freezing vessel.

25. The method of claim 21, wherein spraying the bulk product and spraying the freezing agent are performed concurrently.

26. The method of claim 21, wherein heating the frozen powder comprises transferring heat to the walls of a vessel using a heat transfer fluid.

27. The method of claim 26, further comprising:

removing heat from the walls of the freeze drying vessel during the spraying using a heat transfer fluid cooled using vented gas from production of the freezing agent.

28. The method of claim 21, further comprising:

condensing vapor from the sublimation of the frozen liquid in a condensing vessel.