Abstract:
A method for freezing a food product in a cryogenic freezer includes sensing at least one physical characteristic of the food product in real time, providing a cryogenic substance to the food product for heat transfer at said food product, automatically self-adjusting the heat transfer at the food product responsive to the sensing the at least one physical characteristic, and continuously self-adjusting the heat transfer for bringing the food product to a select temperature. A related freezer apparatus is also provided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present embodiments relate to cryogenic food freezing systems such as for example tunnel freezers, and those systems that automatically adjust an atmosphere, conveyor belt speed, blower speed, exhaust speed (extraction rates) and freezer temperatures of the freezer. 
         [0002]    All known cryogenic food freezing systems require trained personnel to operate the systems to accordingly adjust the freezing conditions of same. Production rates within a food freezing system processing line are continually changing, i.e., inlet temperatures and hence heat load of products to be chilled/frozen by the system change, as do conditions in the processing facility which may impact the chilling/freezing of the food products. If the food freezing system is not controlled and adjusted to properly compensate for changing inlet and external conditions of the freezing system, the overall operating efficiency of the system will be impacted such that the system is used inefficiently, product such as food product is chilled or frozen inefficiently and ineffectively, and the cryogenic substance for chilling and/or freezing is unnecessarily wasted. In order to control and adjust such a system, it is typical for operators not to make immediate adjustments to compensate for food production line variability, because of the labor intensity to do so and the fact that very often such operators are not aware of the variable changes that occur along the processing line of the food freezer. 
       SUMMARY OF THE INVENTION 
       [0003]    There is therefore provided a method for freezing a food product in a cryogenic freezer which includes sensing at least one physical characteristic of the food product in real time; providing a cryogenic substance to the food product for heat transfer at said food product; automatically self-adjusting the heat transfer at the food product responsive to the sensing the at least one physical characteristic; and continuously self-adjusting the heat transfer for bringing the food product to a select temperature. 
         [0004]    There is also provided a related cryogenic freezer for a food product which includes a housing having an internal chamber and a cryogen delivery member disposed therein; a conveyor for conveying the food product through the internal chamber; a laser scanner disposed at an inlet of the housing for scanning a cross-sectional area of the food product entering the cryogenic freezer; a pair of infrared (IR) temperature sensors, wherein a first IR sensor is disposed downstream of the laser scanner and upstream of an inlet to said internal chamber, and a second IR sensor is disposed downstream of an outlet of said internal chamber; and a controller interconnecting the conveyor, the laser scanner, and the pair of IR temperature sensors for automatically self-adjusting heat transfer of the food product in the internal chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0005]    For a more complete understanding of the present invention, reference may be had to the following description of exemplary embodiments considered in connection with the accompanying drawing Figure, of which: 
           [0006]    The Figure shows a side plan view in cross-section of a self-adjusting cryogenic food freezer embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0007]    Before explaining the inventive embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. 
         [0008]    In the following description, terms such a horizontal, upright, vertical, above, below, beneath and the like, are to used solely for the purpose of clarity illustrating the invention and should not be taken as words of limitation. The drawing is for the purpose of illustrating the invention and is not intended to be to scale. 
         [0009]    Basically, the system embodiment of the Figure and described herein will actively monitor in real time both incoming and outgoing food product conditions and production rates. Conditions within the cryogenic food freezer are also monitored in real time. Use of an intelligent control philosophy for the present cryogenic food freezing system can automatically be adjusted and adapted to optimum efficiencies with a variety of process inputs to the system. The end result is a more efficient freezing solution along with additional data which can be fed to both upstream and downstream processes for a more effective control and uniformity of a food chilling or freezing process for the food product, and efficient use of the cryogenic substance for chilling and/or freezing of same. 
         [0010]    A cryogenic food freezing system is one of many components arranged along a food processing line. The customers of such food freezing systems are concerned with the commercial value drivers, such as maximum product yield, improving process efficiency (such as reduced downtime of the system), and a reduction in the overall processing costs to use the system. 
         [0011]    In view of the foregoing, there is provided a self-adjusting cryogenic food freezing apparatus  10  or apparatus for use in a food processing line in which products, such as any type of food product, are chilled or frozen for continuous or batch freezing applications. The apparatus  10  includes a housing  12  consisting of a plurality of sidewalls  14  for defining an internal space  16  or chamber therein. One of the sidewalls  14  is provided with an inlet  18 , while another one of the sidewalls, usually positioned at an opposite end of the housing  12 , includes an outlet  20 . The inlet  18  and the outlet  20  provide for communication with respect to the chamber  16  and through which moves a transport assembly  22  or conveyor belt for conveying food product  24  from the inlet through the chamber to the outlet. The conveyor belt  22  can be of any know type of construction, such as for example a stainless steel mesh belt. 
         [0012]    Cryogen is introduced through a pipe  26 , the cryogen pipe, into the chamber  16 . The pipe  26  includes a valve  28  such as a modulating control valve, to control or restrict the amount of cryogen being introduced into the chamber  16  of the apparatus  10 . The cryogen pipe  26  is in fluid communication with a remote source (not shown) of cryogen which can be for example nitrogen, liquid nitrogen (LIN) or carbon dioxide snow. An end  30  of the pipe  26  in the chamber  16  is branched or split into a plurality of sections  32  or portions to provide a spray bar which operates as a distribution arm or manifold for the cryogen being provided from the pipe. The sections  32  may also be provided with at least one and for most applications a plurality of nozzles  34  which distribute or jet a spray  36  of the cryogen onto the food product  24  passing proximate thereto on the conveyor belt  22 . The cryogen spray  36  is usually in the form of LIN or solid carbon dioxide (CO 2 ) snow for providing a thorough heat transfer effect of the underlying food product  24  passing beneath the nozzles  34 , 
         [0013]    The housing  12  is also provided with at least one and for most applications a plurality of motors  38 , each one of which is connected to and drives a corresponding fan  40  for circulating the disbursed cryogenic spray and cold cryogenic gas  36  within the chamber  16 , and to maintain atmosphere in the chamber to a substantially uniform temperature, although depending upon the cryogen process being used the atmosphere could be isothermal, co-current (temperature profiles in the same direction within the freezer atmosphere) or counter-current (temperature profiles in opposite or dissimilar directions within the freezer atmosphere). Movement of the fans  40  provides for distributing the cryogenic spray  36  across the chamber  16  so that food product  24  entering at the inlet  18  begins to be subjected to heat transfer and therefore chilling and/or freezing before reaching the portions  32  of the spray bar. The motor ( 38 ) is mounted external to the housing  12  so that heat from the motor(s) has minimal effect on the atmosphere in the chamber  16 . 
         [0014]    An array of sensors can be placed at the inlet  18 , the outlet  20 , and the chamber  16  to collect information about the chamber atmosphere and the status of the food products  24  as same are introduced into, subjected to, and depart from the chilling and/or freezing process of the apparatus  10 . In particular, an infrared (IR) temperature sensor  42  can be mounted for actuation at the inlet  18 , while another IR temperature sensor  44  is mounted at the outlet  20 . At least one other temperature sensor  46  can be mounted for sensing a temperature of the chamber  16 . The sensor  46  may be for example a resistance temperature detector (RTD), which is more accurate at lower temperatures than a thermocouple. An oxygen (O 2 ) sensor  48  is also provided to sense the oxygen content of the chamber  16 . The O 2  sensor  48  is used to determine if air is being drawn into the freezing process from external to the housing  12 . 
         [0015]    A laser scanner  50  is mounted proximate the inlet  18  upstream of the IR temperature sensor  42 , and which precisely records the continuous cross-section area of the food product entering the freezer at the inlet. 
         [0016]    A controller  52  processes real time data from the sensors  42 ,  44 ,  46 ,  48  (collectively  42 - 48 ); the controller  52  interconnecting the sensors  42 - 48 , the operation of the conveyor belt  22 , the laser scanner  50 , and the valve  28  in such a way so as to allow the freezer apparatus  10 , without the necessity of an operator, to automatically control and optimize food freezing with the apparatus, Data collected from the sensors  42 - 48 , including the laser scanner  50 , can also provide feedback to the plant operator to permit more precise oversight and control of other processes positioned upstream and downstream of the present apparatus  10 , 
         [0017]    Still referring to the Figure, the laser scanner  50  provides data which can be used to calculate mass flow rates and loading of the food product  24  on the conveyor belt  22 . The IR temperature sensor  42  at the inlet  18  will sense and monitor the food product temperature at the inlet with known thermal properties of the food product, ie the two data points described above: the cross-sectional area of the product  24  entering the freezer and the mass flow rates and loading of the product on the conveyor belt  22 , such can be used to calculate real time production rate and therefore heat load of the food product entering the process provided by the apparatus  10 . Accordingly, a speed of the conveyor belt  22  and the injection rates of the cryogen introduced by the pipe  26  into the chamber  16  can be adjusted in real time or “on the fly” to match food product heat load and maximum belt loading of the food product to provide a higher operating efficiency of heat transfer at the food product in the apparatus  10 . The IR temperature sensor  44  located at the outlet  20  of the apparatus  10  is used to check heat removal from the product which has occurred from the process of the present embodiment. Accordingly, depending upon the heat removal that has occurred, delivery of the cryogen spray  36 , speed of the fans  40 , and speed of the conveyor belt  22  can be adjusted automatically to compensate for any inefficiencies or discrepancies in chilling and/or freezing the food product  24 . 
         [0018]    The freezer apparatus  10  and related process of the embodiments provide for an increase in processing efficiencies for the food product through the freezer apparatus and accordingly, a substantial reduction in manual labor necessary to “tune” the apparatus for the food product  24  being processed (chilled or frozen) in the apparatus. 
         [0019]    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 can be combined.