Method for heating or cooling product containers

Information

  • Patent Grant
  • 6194015
  • Patent Number
    6,194,015
  • Date Filed
    Monday, October 18, 1999
    24 years ago
  • Date Issued
    Tuesday, February 27, 2001
    23 years ago
Abstract
Apparatus and methods for transferring heat between a heat transfer liquid and a plurality of moving containers of food product. The containers are conveyed by a perforated conveyor at least partially submerged in a pool of the heat transfer liquid and are showered at the same time with the heat transfer liquid. The pool of heat transfer liquid continuously drains and recirculates through either a heater or a chiller. A vibrator unit vibrates the pool of heat transfer liquid, the conveyor and the containers during the heat transfer operation.
Description




FIELD OF THE INVENTION




The present invention generally relates to heat exchange systems and, more specifically, to apparatus and methods for heating or cooling product containers, for example, filled with liquid-based food product.




BACKGROUND OF THE INVENTION




In many food processing operations, such as in the processing of fruit and vegetable products, the food product must be heated and maintained at a sterilizing temperature and then cooled sufficiently to allow further packaging and transport. After proper heat sterilization, the product is either cooled and then packaged under aseptic conditions, or the product is immediately packaged in a heated, sterile condition and then cooled to a temperature sufficient for additional packaging and shipping. The product may also be packed cold in a container, and then sealed, sterilized and cooled in the container. Cooling the sterilized food product while the product is sealed within a container, such as a flexible bag, eliminates the need for filling sterile bags with cooled, sterile food product under aseptic conditions. Instead, the bag may be filled with heated, sterilized food product and sealed to ensure that the food product remains sterile. To achieve acceptable cooling times, complex cooling equipment has generally been designed to accommodate specific package types. On the other hand, simpler conveying systems that merely spray the packages with chilled liquid result in longer cooling times and, therefore, higher processing costs.




Many different systems have been proposed and used for continuously heating and/or cooling containers of food product along a moving production line. As mentioned above, some of the more complex systems include mechanisms or structure for agitating the food contents as the containers are heated or cooled by liquid or gas heat transfer media. For example, cans of liquid-based food product have been agitated back and forth or rolled as a conveyor moves the cans past nozzles that spray the cans with a heat transfer liquid. With other equipment, pouches or bags have been manipulated by rollers or rocked back and forth on specialized carriers while the pouches are conveyed through a heat transfer media.




To address various problems of the past, it would be desirable to provide apparatus and methods for heating and/or cooling product quickly and uniformly, whether the product is packaged in a rigid or flexible container.




SUMMARY OF THE INVENTION




The present invention therefore generally provides apparatus for transferring heat between a heat transfer liquid and a plurality of flexible or rigid containers filled at least partially with food product. The apparatus may comprise essentially one module or a series of modules linked to form a longer system. The apparatus generally comprises a perforated conveyor having a conveying surface for supporting the containers and transferring the containers through a housing structure. A conveyor pan receives the perforated conveyor and includes an open top portion and at least one drain. The conveyor pan holds a continuously recirculating pool of heat transfer liquid at a level disposed above the conveying surface of the perforated conveyor. In this manner, heat is transferred between the pool of heat transfer liquid and the contents of the containers. In addition, a heat transfer liquid distributor is spaced above the perforated conveyor and showers the containers with heat transfer liquid directed through the open top portion of the conveyor pan. This effects further heat transfer between the showering liquid and the contents of the containers. Finally, a vibrator unit is operatively connected with the conveyor pan and vibrates the conveyor pan, the perforated conveyor, the pool of heat transfer liquid and the containers of food product as the containers are moved by the conveyor. Uniform, efficient heat transfer therefore occurs between the heat transfer liquid and the food product in the containers. The apparatus accomplishes this result while also being easily incorporated into existing processing operations and being versatile enough to accommodate a wide variety of container sizes and types.




In the preferred embodiment, a conveyor support contacts the perforated conveyor and is mounted along a bottom surface of the perforated conveyor pan to transmit vibrations between the vibrator unit and the perforated conveyor. A liquid return pan is mounted below the conveyor pan for receiving the heat transfer liquid from the drain. The liquid is drained in a continuous manner or, in other words, in a manner which maintains a predetermined liquid pool level that partially submerges the containers moving along the conveyor. The drain of the conveyor pan preferably comprises multiple perforations in a lower surface of the conveyor pan. These perforations generally occupy an area opposed to the conveying surface such that the pool of heat transfer liquid drains across the conveying surface in a generally uniform manner. The perforated conveyor is a continuous conveyor that has a lower portion passing through the liquid return pan. The perforated conveyor additionally includes a plurality of high friction elements on the conveying surface for maintaining the containers in contact with the perforated conveyor and moving through the pool of liquid. Other structure may be provided for this purpose in addition or as an alternative to the high friction elements.




The housing structure includes an inlet end and an outlet end and the perforated conveyor is more specifically a flexible belt having portions disposed generally at the inlet and outlet ends. Guide elements contact these portions of the belt and direct the belt downwardly into the conveyor pan. The liquid distributor is preferably a liquid distributing pan adapted to hold a volume of the heat transfer liquid. The liquid distributor pan includes a lower, perforated surface generally occupying an area opposed to and covering the conveying surface of the perforated conveyor. Therefore, the liquid distribution pan uniformly showers the containers on the conveying surface with chilled or heated liquid. A heat exchanger receives the heat transfer liquid in a recirculation path generally between the conveyor pan and the liquid distributor pan to continuously heat or cool the liquid. Finally, a plurality of pneumatic vibration dampeners are mounted between the housing structure and the conveyor pan and, more preferably, between a conveyor pan support structure and the conveyor pan. These devices isolate vibrations of the conveyor pan from the remaining portions of the housing structure, and provide height adjustment to maintain the conveyor pan at optimum operational height.




The invention is also directed to methods for effecting heat transfer between a plurality of containers filled with food product and a heat transfer liquid. These methods may be performed using apparatus as generally described above, and involve moving the plurality of containers along a perforated conveyor which is positioned to partially submerge the containers within a pool of the heat transfer liquid. Heat transfer liquid showers the containers as they move along the perforated conveyor. The pool of heat transfer liquid is drained to maintain a level that partially submerges the containers. Finally, the perforated conveyor, the pool of heat transfer liquid, and the containers are vibrated during the conveying and showering operation to agitate the product within the container and effect more uniform heat transfer.




Various additional objects, advantages and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of an apparatus constructed in accordance with the preferred embodiment;





FIG. 2

is a cross sectional view taken generally along line


2





2


of

FIG. 1

;





FIG. 3

is a partially fragmented end view of the apparatus shown in

FIG. 1

;





FIG. 4

is a partially fragmented top view of the apparatus shown in

FIG. 1

; and





FIG. 5

is a side elevational view showing a longer heat exchange system linking together several heat transfer modules constructed according to the invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring first to

FIGS. 1-4

, an apparatus


10


constructed in accordance with the preferred embodiment includes a housing structure


12


. It will be appreciated that apparatus


10


may take on many different forms in accordance with this invention, however, one useful form is that of a module which is useful alone or linked with like modules to form a longer heat transfer path, as will be appreciated from the description to follow. Housing structure


12


may include a plurality of access panels


14


and may generally include various types of frame structure


16


for support purposes.




Apparatus


10


more specifically includes a perforated conveyor belt


20


, which may be formed from any suitable perforated material or structure allowing a heat transfer liquid to flow through the conveyor. One suitable conveyor belt is sold under No. IS62051S-HA-HF, obtainable from KVP/Falcon, located in Rancho Cordova, Calif. Perforated conveyor belt


20


is preferably a continuous conveyor belt which moves from left to right, as viewed in

FIG. 2

, over respective wheels


22


,


24


. Wheels


22


,


24


have projections


22




a


,


24




a


that engage the perforations or other spaces within belt


20


. A suitable drive assembly


26


, which may comprise a conventional motor and gear drive, is connected to wheels


22


by a drive shaft


26




a


for driving perforated conveyor belt


20


in a clockwise direction, as viewed in FIG.


2


. Wheels


24


act as idler wheels to guide the opposite end of conveyor


20


. As further shown in

FIG. 2

, perforated conveyor belt


20


includes a conveying surface


28


receiving a plurality of pouches


30


containing food product, such as liquid-based fruit or vegetable product. Pouches


30


ride along conveying surface


28


while being partially submerged within a pool


32


of heat transfer liquid. Liquid pool


32


may comprise either a heated liquid or a chilled liquid depending on whether a heating or a cooling operation is being performed by apparatus


10


. Also, although apparatus


10


is particularly useful for effecting heat transfer to or from pouches


30


, more rigid containers may also be processed with apparatus


10


. Preferably, pouches


30


are only about half submerged in liquid pool


32


, as shown in

FIG. 2

, to prevent pouches


30


from floating or losing substantial contact with conveying surface


28


. To further promote engagement of pouches


30


with conveying surface


28


, conveying surface


28


preferably includes a plurality of high friction elements


34


, as best shown in FIG.


1


. These may be replaced or augmented with additional engagement structure, such as upstanding members, for maintaining the movement of pouches


30


with conveyor belt


20


.




Perforated conveyor belt


20


is contained within and supported by a conveyor pan


40


. In this preferred embodiment, conveyor pan


40


includes three sections, namely, an inlet section


40




a


, an intermediate section


40




b


, and an outlet section


40




c


. Inlet and outlet sections


40




a


,


40




c


are each sloped upwardly to contain the pool of liquid


32


within conveyor pan


40


. Rubber connecting material


42


,


44


may affix inlet and outlet sections


40




a


,


40




c


to respective ends of intermediate section


40




b


in a fluid-tight manner. One suitable rubber connecting material is available from Godiva Rubber Company, located in San Mateo, Calif. A plurality of skid bars


46


, or other types of support members, are affixed to the lower, interior surface of conveyor pan


40


to allow perforated conveyor belt


20


to ride in contact with conveyor pan


40


. Respective shoes


48


,


50


hold conveyor belt


20


down against respective bottom walls


52


,


54


,


56


of conveyor sections


40




a


,


40




b


,


40




c


. More specifically, conveyor belt


20


is held against skid bars


46


. Bottom wall


56


of intermediate conveyor pan section


40




b


includes a plurality of perforations


58


preferably spread across the entire width of conveyor belt


20


and extending along thee length of intermediate conveyor pan section


40




b


for uniformly draining conveyor pan


40


in a continuous manner. A conveyor support


60


, which may be in the form of a frame structure having perpendicularly affixed frame members


60




a


,


60




b


, supports conveyor pan


40


, and the liquid pool


32


and pouches


30


during operation. A plurality of pneumatic vibration dampeners


62


,


64


(

FIG. 2

) are provided between conveyor support


60


and other support members


65


of housing structure


12


. These isolate vibrations of conveyor pan


40


and support


60


from other portions of housing structure


12


and provide height adjustment to maintain conveyor pan


40


and support


60


at optimum operational height. Suitable pneumatic vibration dampeners may be obtained from Firestone, located in Carmel, Ind. Conventional pneumatic controls


66


, which may include an air accumulator


68


, are connected to operate pneumatic vibration dampeners


62


,


64


. At least one vibrator unit


70


is connected to the underside of conveyor support


60


and vibrates conveyor pan


40


, perforated conveyor belt


20


, the pool


32


of heat transfer liquid and pouches


30


during operation. A suitable vibrator unit may be obtained as Model BK 40-35/4 from Invicta, located in Charleston, S.C. As shown in

FIG. 3

, vibrator unit


70


may include eccentric, rotated weights


72


to produce vibrations which are ultimately transmitted to the pool


32


of liquid and to pouches


30


.




A liquid distributor pan


80


is mounted above intermediate conveyor pan section


40




b


and holds a supply


82


of freshly chilled or heated liquid. Liquid distributor pan


80


also includes bottom surface


84


having perforations


86


and extending across substantially the entire length and width of the portion of conveyor belt


20


riding within conveyor pan section


40




b


. Pouches moving in this area therefore receive a shower of freshly chilled or heated liquid


82


. Liquid distributor pan


80


is filled, preferably in a continuous manner, by one or more conduits


88


. Conduits


88


receive liquid


82


from a heat exchanger


90


which may be a heater or a chiller. As shown in

FIG. 2

, heat exchanger


90


receives heat transfer liquid


92


from a lower liquid return pan


94


through a drain


96


. Liquid return pan


94


is mounted to housing structure


12


and disposed directly below conveyor pan


40


to receive the liquid which continuously drains from pool


32


. This liquid drains continuously between the frame members


60




a


,


60




b


of conveyor pan support


60


. As also shown in

FIG. 2

, perforated conveyor belt


20


loops back through liquid return pan


94


and is guided over frame members


98


,


100


, which may have rounded upper surfaces with low friction pads or surfaces


98




a


,


100




a.







FIG. 5

illustrates a longer system


110


for heating or cooling product containers in essentially the same manner as apparatus


10


described with respect to

FIGS. 1-4

. System


110


may include multiple modules


112


,


114


,


116


that operate as described with respect to apparatus


10


above. In system


110


, a single perforated conveyor belt


118


extends through each module


112


,


114


,


116


and is rotated by a single drive


120


connected with conveyor drive wheels


122


. Like apparatus


10


, idler wheels


124


are disposed at the opposite end of system


110


. A conveyor pan


128


having inlet, intermediate, and outlet sections


128




a


,


128




b


,


128




c


extends through modules


112


,


114


,


116


. One or more conduits


130


supply heat transfer liquid to the interior of modules


112


,


114


,


116


in the same manner as discussed above. These may supply the heat transfer liquid to liquid distributor pans (not shown) respectively mounted within modules


112


,


114


,


116


. Each module


112


,


114


,


116


includes a liquid return pan


132


,


134


,


136


, each having a drain


138


,


140


,


142


. Drains


138


,


140


,


142


may be connected with one or more heat exchangers in a recirculation path leading back to supply conduits


130


, as discussed with respect to

FIGS. 1-4

. It will be appreciated that system


110


may include more or less modules than the three shown in FIG.


5


. The specific size of system


110


will depend, for example, on the heat transfer requirements, the quantity of given units over time, and size requirements of the individual product containers processed by system


110


.




As one additional example of heat exchanging apparatus that may be constructed in accordance with the invention, one or more apparatus


10


and/or apparatus


110


may be combined in a heating and cooling operation. For example, one apparatus


10


or


110


may be used initially to heat and sterilize pouches


30


or other containers of product, while another apparatus


10


or


110


may be positioned at the outlet thereof to receive the pouches


30


or other containers for a subsequent cooling operation. In each stage of the process, apparatus


10


and


110


may be utilized in essentially the same manner as described above, with heated liquid being used in the sterilizing section and chilled liquid being used in the cooling section. If desired or necessary for some applications, apparatus constructed according to the invention may include additional heating or cooling elements. Also, apparatus of the invention may be used in conjunction with other heating or cooling apparatus depending on the applications.




The basic operation of apparatus


10


, system


110


, or a combined heating and cooling system, may be understood with reference to

FIGS. 1 and 2

. In this regard, product containers


30


are received on conveyor belt


20


at the left end or inlet end of housing


12


. These product containers, which may be flexible pouches or bags


30


, travel downwardly on conveyor


20


along bottom wall


52


of conveyor pan section


40




a


until they are partially submerged within a pool


32


of heat transfer liquid. Pouches


30


then travel horizontally through liquid pool


32


on conveyor belt


20


as it moves through intermediate section


40




b


of conveyor pan


40


. Pool


32


of heat transfer liquid is supplied continuously by liquid showering into conveyor pan


40


from the supply


82


of liquid contained in liquid distributor pan


80


. More particularly, this liquid continuously drains through perforations


86


contained in the bottom of distributor pan


84


. This liquid supply


82


is continuously replenished from a heat exchanger


90


which may supply freshly chilled or heated liquid through conduits


88


. The pool


32


of liquid contained in conveyor pan


40


is also continuously drained through perforations


58


contained throughout the bottom surface


56


of conveyor pan


40


. This liquid drains into liquid return pan


94


and is eventually recirculated back to heat exchanger


90


. While product containers


30


are conveyed along the bottom surface of conveyor pan


40


, the vibrator unit


70


operates to continuously vibrate conveyor support


60


, conveyor pan


40


, the portion of conveyor


20


within conveyor pan


40


, the pool


32


of heat transfer liquid and, finally, product containers


30


and the product contained therein. Product containers


30


then exit housing structure


12


at the outlet end or right end thereof, as viewed in

FIGS. 1 and 2

. Apparatus


10


thereby provides fast, thorough heat transfer between the heat transfer liquid and the contents of product containers


30


while moving containers on to further packaging operations.




As one example of the potential results of apparatus


10


, prior conveying apparatus which simply included spraying the pouches of product with chilled water required


30


minutes of cooling treatment to reduce a 1½ gallon bag of ketchup from an input temperature of 190° F. to an output temperature of 100° F. using 33° F. water as the cooling liquid. The same apparatus takes 46-48 minutes to reduce the same item from 190° F. to 100° F. using 75° F.-85° F. water as the heat transfer liquid. In contrast, a system constructed in accordance with the invention takes 14 minutes for the same item to be reduced in temperature from 190° F. to 100° F. using 50° F. water as the heat transfer liquid and takes 20 minutes for the same temperature reduction using 77° F. water as the heat transfer liquid.




While the present invention has been illustrated by a description of a preferred embodiment and while this embodiment has been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known.



Claims
  • 1. A method of effecting heat transfer between a heat transfer liquid and a plurality of containers filled with liquid-based food product, the method comprising:moving the plurality of containers along a perforated conveyor which is positioned to partially submerge the containers within a pool of the heat transfer liquid, showering the containers moving along the perforated conveyor with the heat transfer liquid, draining the pool of heat transfer liquid to maintain a level thereof which partially submerges the containers, and vibrating the perforated conveyor, the pool of heat transfer liquid, and the containers on the conveyor to uniformly and efficiently transfer heat between the heat transfer liquid and the product in the containers.
  • 2. The method of claim 1 further comprising:recirculating the heat transfer liquid from the pool to a heat exchanger, and showering the containers with the recirculated heat transfer liquid.
  • 3. The method of claim 1, wherein the step of showering the containers further comprises:continuously showering the containers with liquid contained in a perforated pan disposed above the perforated conveyor.
  • 4. The method of claim 1, wherein the step of moving containers along the perforated conveyor further comprises moving pouches along the perforated conveyor.
  • 5. The method of claim 1, wherein the heat transfer liquid is a chilled liquid.
  • 6. The method of claim 1, wherein the step of draining the pool of heat transfer liquid further comprises:allowing the heat transfer liquid to continuously drain through a perforated bottom wall of a conveyor pan which holds the pool of heat transfer liquid and through which the perforated conveyor passes during the moving step.
Parent Case Info

This application is a Divisional of prior application Ser. No. 09/188,950, filed on Nov. 10, 1998 now U.S. Pat. No. 6,073,540.

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