Abstract:
A system processes a food product with a cooling gas and includes a housing with a chamber; a blower in communication with the chamber for circulating the cooling gas; a baffle disposed in the chamber for dividing the chamber into a first region for exposing the food product to the cooling gas and a second region in which the cooling gas is moved by the blower for recirculation to the first region of the chamber; an arcuate member disposed in the chamber in spaced relationship with the baffle for providing a flow path between the first and second regions, the arcuate member coacting with the baffle to guide the cooling gas into the flow path; and conveyor means disposed for movement through at least one of the first and second regions for supporting and delivering the food product through the cooling gas.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Conventional tunnel freezers utilize axial flow fans mounted above the product to generate gas flow which impinges the surface of the product and promotes heat transfer. Local velocities from these fans are high, in the range of 2000 feet per minute (fpm). However, there are significant gaps between fans and therefore, large areas are not covered with a uniform high velocity flow. As a result, the total heat transfer coefficient for these processes is low. In addition, these freezers require sufficient height to allow gas to enter from above the axial fan, then be pressurized and distributed onto the product perpendicular to the surface of the product. 
         [0002]    Impingement heat transfer is a means of applying airflow for freezing which is very effective at achieving high heat transfer coefficients. With impingement freezing, nearly 85% of the total freezer area can achieve high velocity airflow. However, the gas flow distribution system for impingement freezing is very complicated, as gas must be pressurized, forced through an impingement plate (having 5% open area), fed into specially designed return channels and then brought back into the fans to be recirculated. These systems are costly to build, complex, difficult to clean and to maintain the proper openings of the impingement plates during operation as they tend to clog with cryogenic freezing snow and ice. To unclog and remove the snow and ice, a plate vibration assembly must be installed, which adds cost and complexity to the system. 
       SUMMARY OF THE INVENTION 
       [0003]    One embodiment of the invention provides an apparatus for processing a food product with a cooling gas, comprising a housing; a chamber disposed in the housing; a blower in communication with the chamber for circulating the cooling gas in the chamber; a baffle disposed in the chamber for dividing the chamber into a first region of the chamber for exposing the food product to the cooling gas and a second region of the chamber in which the cooling gas is moved by the blower for recirculation to the first region of the chamber; an arcuate member disposed in the chamber in spaced relationship with the baffle for providing a flow path between the first and second regions, the arcuate member coacting with the baffle to guide the cooling gas into the flow path; and conveyor means disposed for movement through at least one of the first and second regions for supporting and delivering the food product through the cooling gas. 
         [0004]    Another embodiment of the invention provides a method of applying a cooling gas to a food product, comprising conveying a food product along a first path to be cooled in a chamber for cooling; circulating a cooling gas in the cooling chamber along a second path perpendicular to an entire length of the first path; and exposing the food product to the cooling gas moving along the second path for an entire length of the first path in the cooling chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    For a more complete understanding of the embodiments of the invention, reference may be had to the following drawings taking in conjunction with the description of the invention, of which: 
           [0006]      FIG. 1  shows a schematic cross-section view of a single belt freezer embodiment of the invention. 
           [0007]      FIG. 2  shows the embodiment of  FIG. 1 . 
           [0008]      FIG. 3  shows a schematic cross-section view of a dual belt freezer embodiment of the invention. 
           [0009]      FIG. 4  shows a schematic cross-section view of another single belt freezer embodiment of the invention. 
           [0010]      FIG. 5  shows a schematic cross-section view of still another single belt freezer embodiment of the invention. 
           [0011]      FIG. 6  shows a schematic cross-section view of another dual belt freezer embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0012]    The embodiments of  FIGS. 1-6  distribute airflow across a width of the freezer tunnel so that food product therein is exposed to a high velocity, for example of 2000 feet per minute (fpm), gas flow throughout the freezing process. By applying the gas as a ‘cross flow’ across a width of the belt, i.e. transverse to the direction of the belt&#39;s movement as shown in  FIGS. 1-6 , all of the freezer achieves the high velocity gas flow and the overall heat transfer coefficient is significantly higher than known systems. The gas flow may be applied to cover the entire or 100% of the surface area of the belt upon which the food product is transported. Testing has shown heat transfer coefficients to be as much as 300% higher using the freezer apparatus with the airflow configuration of the present embodiments. 
         [0013]    The gas flow assembly in the embodiments provides a significant amount of space savings above the product. 
         [0014]    As a result, the embodiments of  FIGS. 1-6  can be as much as 300% shorter in length and 300% lower in height, and still achieve comparable production rates and greater efficiencies. 
         [0015]    The embodiments have a much smaller footprint, are compact and extremely easy to clean. It is estimated that the cross flow tunnel freezer embodiments will realize at least a 50% cost savings over a comparable production rate impingement freezing system. 
         [0016]    Benefits of the embodiments herein of  FIGS. 1-6  include: 
         [0017]    a) Heat transfer coefficients achieved in the cross flow airflow configuration at velocities in the range of 2000 ft/min (610 m/min) are comparable to those achieved in a full scale impingement freezer. These higher heat transfer coefficients are achieved with reduced power consumption over current technologies. 
         [0018]    b) The cross flow tunnel freezer embodiments have simplicity in construction and reduced capital equipment costs. Overall height will be minimal, compared to conventional tunnel and impingement freezers. The embodiments also provide sanitation benefits, i.e. easier to clean and to maintain the cleanliness. 
         [0019]    c) The airflow lends itself to crust freezing applications, such as for example crusting of meat logs (see  FIG. 2 ). One will be able to achieve an even crust over the product surface with much greater efficiency and uniformity than that of a standard tunnel freezer. The embodiments herein may be suited for front end of line (“FEOL”) use in that they crust freeze products to trap moisture in the product so that a mechanical freezer can thereafter freeze the remaining portion of the product. The present embodiments may be used with flat food products, i.e. those products with low cross-sectional profile or high surface area to weight ratios. 
         [0020]    Referring to the FIGS.,  FIG. 1  shows a single belt cross flow tunnel freezer configuration. Referring also to  FIGS. 2-3 , a freezer apparatus embodiment of the invention is shown generally at  10  and consists of a housing  12  having a chamber  14  therein in which is disposed one or a plurality of open mesh conveyor belts  16  for transporting food products  18  to be frozen, chilled or crusted within the freezer. 
         [0021]    An airflow baffle  20  is disposed in the chamber  14  to extend over in spaced relationship from and be in registration with an entire length of each one of the conveyor belts in the chamber  14  to provide a first region “X” for chilling the air, and a second region “Y” wherein the chilled air freezes food products as shown in the  FIGS. 1-3 . The baffle  20  is solid or of nonporous construction, and segregates or divides the chamber  14  into the first and second regions, X and Y. In effect, airflow or cooling gas  23  provided to the first region X has a cooling fluid such as a cryogen gas injected by spigots or nozzles  22  into the airflow  23 . The nozzles  22  are disposed in the chamber  14  for charging the gas flow with cryogen. The cryogen may be supplied as a cooling or cold gas such as for example gas selected from carbon dioxide, nitrogen and combinations thereof. The airflow  23  is prevented by the solid baffle  20  from contacting the food products while the air is receiving the cryogen gas in the region X. The airflow baffle  20  serves to establish a circulation path in the chamber  14 . 
         [0022]    Thereafter, the cryogen gas airflow  23  is directed along an interior arcuate sidewall surface  24  to the second region Y for providing the cryogen airflow  23  to the food products  18 . The airflow  23  contacts all surfaces of the food product  18  due to the open mesh conveyor belt  16 . The cryogen airflow is exposed to an entire length of the conveyor belt(s) which extends along the chamber  14  of the housing  12 . Thereafter, the cryogen airflow  23  is returned to an inlet  26  of a blower  28  and recycled for subsequent chilling by the cryogen nozzles  22  in the region X. The airflow baffle  20  may be constructed and arranged in the chamber  14  such that a proximal end of the baffle  20  is positioned at the blower  28 , while a distal end of the baffle extends in the chamber  14  toward the sidewall or arcuate member  24 . The airflow  23  is provided along a direction transverse or perpendicular to the direction of movement of the food product  18  on the conveyor belt  16 . 
         [0023]    The freezer apparatus  10  includes the novel arrangement of the airflow baffle  20  to segregate the freezer chamber  14  into a “cryogen charging” region X for the airflow  23 , and a chilling region Y for freezing food product with the airflow  23 , such that the cryogen airflow sweeps across an entire length of the belt  16  in the chamber  14  and the product  18  transverse to movement of the product disposed on the belt  16 . 
         [0024]    The airflow baffle  20  is adjustable with respect to its position in the chamber  14  to accommodate a height of the food product  18  on the conveyor belt  16 , and so airflow  23  efficiency can be maximized for each of the product  18 . The overall height of the housing  12  may be no greater than 508 mm (or approximately 17-20 inches), excluding a height of any exhaust stacks (not shown). Parasitic heat loads will be minimized and overall system pressure drop will be less than that of a conventional impingement freezer. 
         [0025]      FIG. 2  shows the single belt freezer apparatus  10  for crust freezing of the food product  18  such as a meat or deli log. This apparatus provides a high velocity cross flow on a meat log for even and rapid freezing around the circumference of the log. Dwell times in the range of one (1) minute are achieved. Product logs loaded across the width of the belt result in an extremely high capacity log crusting system. Overall cryogen efficiency is much greater than a conventional tunnel as a result of the cross flow circulation. 
         [0026]    The housing  12  may be used as a “module”, whereby a plurality of the modules may be removably attached to each other to provide a crust freezing line. 
         [0027]    Other exemplary embodiments of a freezer constructed in accordance with the invention are illustrated in  FIGS. 3 ,  4 ,  5  and  6 , respectively. Elements illustrated in  FIGS. 3-6  which correspond to the elements described above with respect to the  FIGS. 1-2  have been designated by corresponding reference numerals increased by one hundred, two hundred, three hundred and four hundred, respectively. The embodiments and elements thereof for  FIGS. 3-6  are designed for use in the same manner as the embodiment of  FIGS. 1-2 , unless otherwise indicated. 
         [0028]      FIG. 3  shows the belt freezer apparatus of  FIG. 1  in a dual chamber arrangement shown generally at  110 . This apparatus  110  may be used as a cryogenic production rate booster for conventional dual belt flat product freezers. As production demands of hamburger patty manufacturers increase (there are requirements that now need to produce 8000 lbs/hr), known mechanical freezing systems cannot meet the new requirements. This freezer embodiment, as with the other embodiments of the invention, provides a small footprint, low cost, add-on solution. 
         [0029]    The housing  12 , 112  of the freezer apparatus  10 , 110  may be provided with one or a plurality of doors  30 , 130  as shown in  FIGS. 1-3 . The doors  30 , 130  may be mechanically fitted to the housing  12 , 112  to provide access to the chamber  14 , 114  and conveyor belt(s)  16 , 116  therein. At least one of the doors  30 , 130  and the housing  12 , 112  would have a gasket or seal where the door removably contacts the housing. A floor  19 , 119  of the housing  12 , 112  may be pitched at an angle downward toward the doors  30 , 130  for accumulated debris and liquid to flow toward the doors for removal, instead of accumulating or pooling in the chamber  14 , 114 . The pitch or grade may be for example 3° off the horizontal of the floor of the chamber  14 , 114 . 
         [0030]    Owing to the perspective of  FIGS. 1-6 , only one of the blowers  28  is viewable in the FIGS. However, a plurality of the blowers  28  may be arranged along the housing  12  for communication with the chamber  14 , 114 , etc. 
         [0031]    Embodiments in  FIGS. 4-6  may differ from the embodiments shown in  FIGS. 1-3  in that the embodiments of  FIGS. 4-6  include airflow baffles and conveyor belts constructed and arranged to be exposed to the airflow in a somewhat different manner than the embodiments shown in  FIGS. 1-3 . In addition, and referring to the embodiment of  FIG. 4 , there is a secondary airflow baffle or arcuate member  21  which obviates the need for a side wall of the freezer enclosure to be provided with an arcuate inner surface (such as shown at  24  in  FIG. 1  for example). 
         [0032]    Referring to  FIG. 4 , a freezer apparatus shown generally at  210  includes an interior chamber  214  in which an airflow baffle  220  is disposed for coaction with an arcuate air guide baffle  21 . The baffle  21  may be constructed of solid or nonporous material and formed as an arcuate member as shown in  FIG. 4 . The baffle  21  extends along an entire length of the chamber  214 . The airflow baffle  220  is solid in construction and includes a proximal end which extends from the blower  228  to a position in the chamber  214  away from the blower toward an opposing side wall  230  which can function as a door to the chamber  214 , or to arcuate member  21  discussed below. Disposed below baffle  220  is the secondary air guide baffle  21  which extends from an interior wall  29  near the blower  228  in the housing  212  to an opposed side of the housing proximate the door  230 . The secondary baffle  21  is solid in construction, and is bent or curved as the baffle  21  approaches the door  230 , but does not touch the door. An end of the secondary air guide baffle  21  arches or is turned upward in spaced relation from the door  230  to contact a ceiling  27  or upper interior side wall of the housing  212 . As shown in  FIG. 4 , the secondary baffle  21  is spaced from a bottom  25  of the enclosure  212 . 
         [0033]    Disposed between the airflow baffle  220  and the secondary air guide baffle  21  is a conveyor belt  216  for transporting product  218  in the apparatus  210 . Another conveyor belt  15  is disposed closer to the bottom  25  of the chamber  214 , the belt  15  being disposed beneath the secondary air guide baffle  21 . Alternatively, the belts  15  and  216  are the same, as  FIG. 4  shows a cross-section of a single belt, wherein an upper portion  216  of such belt is disposed between the airflow baffle  220  and the airguide baffle  21 ; while a lower portion of such belt  15  is disposed beneath the air-guide baffle  21 . 
         [0034]    Airflow  223  of the embodiment of  FIG. 4  is moved from the blower  228  through a first region “X”, which is the region also above the secondary air guide baffle  21 . The airflow  223  moves across the region X where it is charged with a cryogen above the airflow baffle  220  and as it approaches the distal end of the airflow baffle  220  it encounters the secondary air guide baffle  21  and is turned or deflected downward to a lower area of the region X for being moved in a transverse direction across the food product  218  being transported on the conveyor belt  216 . The airflow  223  is turned by the arcuate structure of the air guide baffle  21  to be directed between the airflow baffle  220  and the airguide baffle  21  to contact the product  218  on the conveyor belt  216 . Thereafter the airflow is drawn back up into an inlet  226  of the blower  228  for subsequent processing and cooling. Cryogen nozzles  222  replenish the cryogen supply for the airflow  223 . The number of the cryogen nozzles  222  is by way of example only and depending upon the application and the product to be frozen, such will dictate the number of nozzles  222  needed for the embodiment The nozzles  222  are connected to a remote source of cryogen fluid (not shown). 
         [0035]    The lower conveyor belt  15  is actually a return portion of the conveyor belt  216 , i.e. owing to the perspective of the drawing figure, the conveyor belt  216  is transporting the product  218  into or out of the Figure and so what we are viewing is the product  218  being conveyed by the conveyor  216  through the region X after which the product  218  is removed from the freezer apparatus  210  and the conveyor belt is functioning as a continuous loop so that we see the bottom portion  15  of the conveyor belt  216  returning to accept another load of the product  218 . 
         [0036]    In the embodiment of  FIG. 4 , as with the embodiments shown in  FIGS. 1-3 ,  5  and  6 , the airflow  223  is transverse to the direction of movement of the conveyor belt  218  so that the food product  218  is exposed for its entire period of time in the chamber  214  to the chilling airflow  223  as the food product  218  is transported through the freezer apparatus  210 . The solid construction of both the airflow baffle  220  and the secondary airguide baffle  21  segregates the airflow so that same is subjected to the food product  218  only in the region “Y”, not wastefully in the space beneath the secondary airguide baffle  21  at the portion  15  of the conveyor. 
         [0037]    Referring to  FIG. 5 , another embodiment of a freezer apparatus is shown generally at  320 . In this freezer embodiment  310 , the airflow baffle  320  extends from the blower  328  toward but spaced apart from a door  330  of the apparatus  310 . A conveyor  316  for transporting the product  318  to be frozen is disposed in a chamber  314  of the housing  312  such that a lower portion  15  of the conveyor belt  316  is spaced apart from a bottom of the housing  312 . The airflow  323  emitted from the blower  328  proceeds along the space “X” between the conveyor belt  316  and its bottom portion  15 , the airflow  323  prevented from contacting the conveyor belt  316  due to the solid construction of the airflow baffle  320 . As the airflow  323  reaches a distal end of the chamber  314  proximate the door  330 , it is turned or guided in a rearward and an opposite direction by the interior arcuate wall of the door  330  to enter the region “Y” where the airflow  323  is subjected to jet sprays from cryogen nozzles  322  disposed in a roof of the housing  312 . The airflow  323  is in effect “charged” with the freezing cryogen for contacting the food product  318  on the conveyor belt  316  in region Y. Due to the solid construction of the airflow baffle  320 , the airflow  323  charged with the cryogen is prevented from drifting downward into the region “X”, but is instead further guided back to the blower inlet  326  where it is drawn in and recirculated again to the region “X” between the conveyor belt portions  316 , 15 . 
         [0038]      FIG. 6  is another embodiment of the freezer apparatus shown generally at  410 . A housing  412  of the apparatus  410  is constructed with at least one and preferably a plurality of the blowers  428  (only one of which is shown due to the perspective of the drawing figure). The housing  412  is constructed at opposed sides of the blower(s)  428  with elements similar to that shown in the embodiment of  FIG. 5 . That is, the apparatus  410  of  FIG. 6  includes construction of the embodiment of  FIG. 5  replicated at an opposed side of the blower  428 . It can be seen from  FIG. 6  that the airflow  423  and coaction of elements of  FIG. 6  operate similar to that which is disclosed and described with respect to the embodiment of  FIG. 5 .  FIG. 6  therefore provides for a larger volume of the food product  418  to be frozen and/or to be frozen in a lesser amount of time. The embodiment shown in  FIG. 6  serves a purpose similar to the embodiment shown in  FIG. 3 . That is, the embodiment of  FIG. 6  provides a cryogenic production rate booster for conventional dual belt flat product freezers that require larger production demands. 
         [0039]    It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. It should be understood that the embodiments described above are not only in the alternative, but may be combined.