Microwave heating system with enhanced temperature control

• US 9,357,590 B2
• Filed: 03/13/2013
• Issued: 05/31/2016
• Est. Priority Date: 03/14/2012
• Status: Active Grant

• Current Assignee: Microwave Materials Technologies, Inc.
• Original Assignee: Microwave Materials Technologies, Inc.
• Inventors: Kimrey, Harold Dail Jr.
• Primary Examiner(s): ATKISSON, JIANYING CUI
• Application Number:
  US13/799,835
• Publication Number:
  US 20130240516A1
• Time in Patent Office: 1,175 Days
• US Class Current: 1/1
• CPC Class Codes: A23L 3/01 using microwaves or dielectric heating
• CPC Class Codes: A23L 3/02 by heating materials in packages which are progressively transported, continuously or stepwise, through the apparatus
• CPC Class Codes: A23V 2002/00 Food compositions, function of food ingredients or processes for food or foodstuffs
• CPC Class Codes: A61B 90/70 Cleaning devices specially adapted for surgical instruments
• CPC Class Codes: A61L 2/04 Heat A61L2/08 takes precedence
• CPC Class Codes: A61L 2/12 Microwaves
• CPC Class Codes: A61L 2202/21 Pharmaceuticals, e.g. medicaments, artificial body parts
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps
• CPC Class Codes: A61L 2202/26 Textiles, e.g. towels, beds, cloths
• CPC Class Codes: B65B 55/06 by heat
• CPC Class Codes: H01L 21/67201 characterized by the construction of the load-lock chamber
• CPC Class Codes: H05B 6/68 for monitoring or control
• CPC Class Codes: H05B 6/70 Feed lines
• CPC Class Codes: H05B 6/78 Arrangements for continuous movement of material
• CPC Class Codes: H05B 6/782 wherein the material moved is food
• CPC Class Codes: H05B 6/80 Apparatus for specific applications stoves or ranges F24C7/02

Abstract

A microwave heating system configured to heat a plurality of articles is provided. The microwave heating system includes a thermalization zone for adjusting the temperature of the articles disposed therein to be substantially uniform and a microwave heating zone for heating the thermalized articles. At least one of the thermalization zone and microwave heating zone are liquid-filled and may include a plurality of fluid agitators for discharging jets of liquid medium toward the articles at multiple locations within the chamber.

Claims

1. A process for heating a plurality of articles in a microwave heating system, said process comprising:

(a) passing said articles through a pressurized microwave chamber via a conveyance system, wherein said microwave chamber is at least partly filled with a liquid medium and said articles are submerged in said liquid medium;

(b) generating microwave energy via one or more microwave generators;

(c) introducing at least a portion of said microwave energy into said microwave chamber via one or more microwave launchers;

(d) heating said articles in said microwave chamber using at least a portion of said microwave energy introduced therein; and

(e) during at least a portion of said heating of step (d), agitating at least a portion of said liquid medium within said microwave chamber, wherein said agitating includes discharging a plurality of jets of said liquid medium toward said articles at multiple locations within said microwave chamber, wherein each of said lets of said liquid medium has a Reynolds number of at least 4,500.

2. The process of claim 1, wherein said multiple locations are axially spaced along the central axis of elongation of said microwave chamber, wherein at least a portion of said jets are directed in a direction generally perpendicular to said central axis of elongation of said microwave chamber.

3. The process of claim 1, wherein said multiple locations are circumferentially spaced along the interior cross-section of said microwave chamber, wherein at least a portion of said jets are directed radially inwardly toward the central axis of elongation of said microwave chamber.

4. The process of claim 1, wherein said heating of step (d) is capable of increasing the temperature of said articles by at least 50°

C.

5. The process of claim 1, wherein said heating of step (d) is carried out at a heating rate of least 25°

C. per minute.

6. The process of claim 1, wherein said introducing of step (c) includes discharging microwave energy into said microwave chamber via at least one pair of axially spaced microwave launchers disposed on the same side of said microwave chamber, wherein said agitating includes discharging said jets from one or more jet manifolds disposed between axially adjacent microwave launchers.

7. The process of claim 1, further comprising subsequent to said heating of step (d), passing the heated articles through a holding zone, wherein the temperature of said articles in said holding zone is maintained at or above a specified minimum temperature for a time period of at least 2 minutes and not more than 15 minutes.

8. The process of claim 7, wherein said specified minimum temperature is at least 120°

C. and wherein said holding zone has a pressure of at least 10 psig.

9. The process of claim 1, further comprising, prior to said passing of step (a), thermalizing said articles in a thermalization zone to thereby adjust the temperature of said articles to a substantially uniform temperature, wherein said thermalized articles are passed through said microwave chamber in step (a).

10. The process of claim 1, wherein said microwave chamber is at least partially filled with a liquid medium comprising water and is pressurized to at least 10 psig, wherein said microwave system sterilizes said articles at a rate of at least 20 packages per minute per convey line.

11. The process of claim 10, wherein said articles comprise packaged foodstuffs, medical instruments, or medical fluids.

12. A process for heating a plurality of articles in a microwave heating system, said process comprising:

(a) thermalizing said articles in a thermalization chamber at least partially filled with a liquid medium to thereby produced thermalized articles having a substantially uniform temperature and said articles are submerged in said liquid medium; and

(b) heating said thermalized articles in a microwave chamber, wherein said thermalizing of step (a) includes discharging a plurality of jets of said liquid medium toward said articles at multiple locations within said thermalization chamber, wherein each of said lets of said liquid medium has a Reynolds number of at least 4,500.

13. The process of claim 12, wherein said multiple locations are axially spaced along the central axis of elongation of said thermalization chamber, wherein at least a portion of said jets are directed in a direction generally perpendicular to said central axis of elongation of said thermalization chamber.

14. The process of claim 12, wherein said multiple locations are circumferentially spaced along the interior cross-section of said thermalization chamber, wherein at least a portion of said jets are directed radially inwardly toward the central axis of elongation of said thermalization chamber.

15. The process of claim 12, wherein said substantially uniform temperature of said articles exiting said thermalization zone is at least 20°

C. and not more than 70°

C.

16. The process of claim 12, wherein said articles have an average residence time of at least 2 minutes and not more than 20 minutes in said thermalization zone.

17. The process of claim 12, further comprising subsequent to said heating of step (b), passing the heated articles through a holding zone, wherein the temperature of said articles is maintained at or above a specified minimum temperature for a time period of at least 2 minutes and not more than 15 minutes within said holding zone.

18. The process of claim 12, wherein said liquid medium in said thermalization chamber comprises water.

19. The process of claim 12, wherein said microwave chamber is at least partially filled with said liquid medium.

20. The process of claim 19, wherein said heating of step (b) includes agitating at least a portion of said liquid medium within said microwave chamber, wherein said agitating includes discharging a plurality of fluid jets toward said articles at multiple locations within said microwave chamber.

21. The process of claim 12, wherein said heating of step (b) is carried out to increase the average temperature of each article by at least 50°

C., wherein at least a portion of said heating is carried out at a heating rate of at least 25°

C. per minute.

22. The process of claim 12, wherein said articles comprise foodstuffs, medical fluids, and/or medical instruments.

23. The process of claim 12, wherein said microwave chamber is a liquid-filled chamber pressurized to at least 10 psig during at least a portion of said heating of step (b), wherein said microwave system pasteurizes or sterilizes said articles at a rate of at least 20 packages per minute per convey line.