Abstract:
A spiral freezer for continuous duty in continuous food process lines has a freezer compartment enclosing a double-helix arrangement, of which there is a helical run of a food-carrying conveyor in combination with a helical ramp or slideway for the food-carrying conveyor&#39;s helical run to ascend or descend on. The helical ramp is an assembly of numerous heat exchanger tubes, each wound helically and positioned in set lanes in the overall assembly of the ramp. An external refrigerant-circulating system is connected to circulate refrigerant through the heat exchanger tubes in order that hot components like compressors and condensers be kept outside of the freezer compartment for better energy efficiency. The foregoing conveyor and heat exchanger arrangement provides close proximity between the source(s) of heat in the food product on the conveyor and the sink of that heat to the refrigerant flowing inside the heat exchanger tubes.

Description:
CROSS-REFERENCE TO PROVISIONAL APPLICATION(S)  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/348,007, filed Jan. 10, 2002, and U.S. Provisional Application No. 60/348,059, filed Jan. 11, 2002.  
         [0002]     This application is co-pending with commonly-owned, commonly-invented U.S. patent application Ser. No. ______ *[not yet known, to be inserted by applicant&#39;s attorney], filed on even date herewith and entitled “SPIRAL OVEN, HEAT DELIVERY, ENCLOSURE AND DRIVE.” All three of the foregoing patent disclosures are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     The invention generally relates to large scale food process lines of the type having a series of machines or stations arranged together and performing distinct processes on articles of food product for ultimately producing packaged and frozen food product. The frozen and packaged food product affords distribution to restaurant and/or consumer grocery stores and the like. For example and without limitation, in the case of frozen chicken strips for the fast food or consumer grocery stores, such a food process line might comprise the following stations in series:—1) pre-dust, 2) batter, 3) bread, 4) batter (again), 5) fry and freeze and package and so on.  
         [0004]     Given the foregoing, the invention more particularly relates to a spiral freezer and refrigeration and enclosure therefor which accomplish much of the same work as by the known spiral freezers of large scale food process lines except scalable in a range between large scale and compact extremes.  
         [0005]     A number of additional features and objects will be apparent in connection with the following discussion of preferred embodiments and examples.  
       SUMMARY OF THE INVENTION  
       [0006]     It is an object of the invention to improve energy efficiency with the energy consumption needs of a continuous duty freezer as utilized in continuous food process lines.  
         [0007]     It is another object of the invention to move as many heat-issuing components as possible—including compressors, pumps, motors, condensers, engines or turbines and the like—outside of the freezer compartment so that the cooling duty of the freezer is spared for food product only, and not waste on waste-heat sources.  
         [0008]     It is an additional object of the invention to position refrigerant-carrying heat exchanger tubes close by the main food-carrying run of the freezer&#39;s conveyor in order to achieve close proximity between the source(s) of heat in the food product on the conveyor and the sink of that heat to the refrigerant flowing inside the heat exchanger tubes.  
         [0009]     These and other objects and aspects of the invention are achieved in one version that has a freezer compartment enclosing a double-helix arrangement comprising one of a helical run of a food-carrying conveyor and another of helical heat exchanger tubes. The heat exchanger tubes include refrigerant input points and refrigerant discharge or output points adapted for service connections to a refrigerant circulating system. That way, the refrigerant circulating system can be located outside of the freezer compartment. Heat-issuing components of the refrigerant circulating system—such as and without limitation compressors, pumps, motors, or condensers—are therefore collectively disposed outside of the freezer compartment for improvement in energy efficiency. The double-helix arrangement of conveyor and heat exchanger tubes provides close proximity between the sources of heat in the food product on the conveyor and the sink of that heat to the refrigerant flowing inside the heat exchanger tubes. Preferably the heat exchanger tubes form a helical slideway for the helical run of the conveyor to slide thereon. Optionally the freezer compartment comprises a cylindrical tower sized for closely surrounding the double-helix arrangement.  
         [0010]     The helical run of the conveyor is one aspect of an endless conveyor system of the freezer, and is flanked between an inflow section and an outflow section. The freezer compartment includes an inflow port and outflow port that are sized and arranged for through passage of the conveyor&#39;s inflow and outflow sections respectively. The conveyor further comprises a return run that links the outflow section with the inflow section and extends along a course disposed preferably totally, but at least predominantly outside the freezer compartment.  
         [0011]     Another version of the inventive freezer for continuous duty in continuous food process lines optionally can be reckoned as follows. That is, this one has a conveyor comprising in sequence a food-carrying inflow section and main run and outflow section as well as an empty return run. The main run either ascends or descends in coils from the inflow section to the outflow section for economy of floor space. There is also an inventive arrangement of heat exchanger tubes entwined with the main run. The freezer includes a freezer compartment for enclosing the coiled main run of the food-carrying conveyor and entwined heat exchanger tubes. Such an entwined arrangement of conveyor and heat exchanger tubes provides close proximity between the source(s) of heat in the food product on the conveyor and the sink of that heat to the refrigerant flowing inside the heat exchanger tubes.  
         [0012]     Generally speaking the heat exchanger tubes are entwined by virtue of being interlaced between the coils of the conveyor&#39;s main run. However, preferably the coils wrap a cylindrical surface and the character of the ascension or descension thereof is constant over the extent of the main run such that the main run defines a helical ribbon. That way, the heat exchanger tubes more particularly are arranged in a corresponding helical ribbon arrangement intertwined with the main run&#39;s helical ribbon arrangement. Individual ones of the heat exchanger tubes occupy set lanes in the overall helical ribbon arrangement thereof.  
         [0013]     Aspects of the invention further pertain to a conveyor drive system. It is adapted for thermally isolating its heat-issuing components—such as and without limitation its motors, engines or turbines—from dumping heat into the freezer compartment. This is achieved by placement of such hot components outside of the freezer compartment, and again as is the case with the hot components of the refrigerant circulating system, energy efficiency is promoted.  
         [0014]     An additional way of looking at the invention has it being described as comprising a conveyor which in sequence includes a food-carrying inflow section and coiled run and outflow section linked back up to the food-carrying inflow section by an empty return run. The coiled section either ascends or descends between the inflow and outflow sections. The heat exchanger tubes are arranged for close-proximity extraction of heat from food product carried on coiled run of the conveyor, and the freezer compartment is sized for closely enclosing at least the coiled run of the conveyor. The heat exchanger tubes are arranged in close-proximity in part with the coiled run of the conveyor by virtue of being arranged to undergird the coiled run.  
         [0015]     The freezer further comprises a conveyor drive system. To understand aspects thereof, it may help to consider that the coiled run is arranged as wrapped around the surface of an imaginary cylinder. Accordingly the coiled run defines a hollow cylindrical core in its middle. That way, the conveyor drive system comprises a driven barrel disposed inside the hollow cylindrical core of the coiled run. The barrel impermanently interfaces the coiled run at least along spaced intervals to motivate the conveyor in a direction of advance through the coiled run. The driven barrel is supplied a drive input from outside the freezer compartment by a drive shaft that is passed into the freezer compartment. That way, hot components can be isolated outside the freezer compartment for energy efficiency purposes. The freezer compartment generally forms a tower that closely surrounds the coiled run, and has a floor and ceiling. The barrel is propped or suspended off the floor of the freezer and gapped from the ceiling in order that there is clearance both above and below the barrel for circulation of air currents inside the freezer compartment. For this purpose, freezer preferably further includes a circulating fan for setting up air circulation inside the freezer compartment, blowing or suctioning an air current through the core of the barrel in one direction and inducing a return current in the opposite direction on the outside of the barrel, like a donut skin turning inside out.  
         [0016]     And briefly, among many other desirable aspects of the invention not mentioned above, there is this significant other one. That is, the freezer compartment can be “zoned.” More particularly, the heat exchanger tubes can be differentiated into zones according to elevation. One way to do this has the refrigerant circulating system differentially servicing the differentiated zones of heat exchanger tubes in order to establish elevational zones within the freezer compartment. Preferably the different zones are different not only by elevation but also by performance characteristics such as differentiated according what heat load can be pulled. More simply, an introductory section of the food-carrying main run can be maintained at a given cold temperature while a successive section might be zoned for maintenance at a colder temperature still.  
         [0017]     A number of additional features and objects will be apparent in connection with the following discussion of preferred embodiments and examples.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     There are shown in the drawings certain exemplary embodiments of the invention as presently preferred. It should be understood that the invention is not limited to the embodiments disclosed as examples, and is capable of variation within the scope of the appended claims. In the drawings,  
         [0019]      FIG. 1  is a perspective view of a spiral freezer housed inside an enclosure therefor and in accordance with the invention, wherein the view shows a ¼-tier style of infeed/discharge configuration as an example only for convenience of illustrative purposes;  
         [0020]      FIG. 2  is an enlarged, partial section view of the spiral freezer and enclosure of  FIG. 1 , as taken through a vertical plane containing the central axis;  
         [0021]      FIG. 3  is a section view taken in the direction of arrows III-III in  FIG. 2 ;  
         [0022]      FIG. 4  is a section view taken along line IV-IV in  FIG. 3 ;  
         [0023]      FIG. 5  is a section view taken in the direction of arrows V-V in  FIG. 2 , the cutting plane therefor being in common with that for  FIG. 3  except the vantage point being from above rather than from below; and,  
         [0024]      FIG. 6  is a section view taken in the direction of arrows VI-VI in  FIG. 2 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]      FIG. 1  is a perspective view of a spiral freezer  20  in accordance with the invention, the freezer compartment thereof being enclosed within a cylindrical-tower enclosure  22  therefor. Food product is conveyed through the freezer  20  by means of an endless conveyor belt  24  for which  FIG. 1  shows a ¼-tier style of conveyor infeed  26  to discharge  28  configuration as an example only for convenience of illustrative purposes. That is, the conveyor  24 &#39;s discharge  28  shoots out on a tangent that projects about 90° counter-clockwise (ie., relative the vertical axis of the spiral&#39;s center) from the tangent of the infeed  26 . In the industry, other configurations are known including without limitation {fraction ( 1 / 2 )}-tier (180°), ¾-tier (270°) and full tier (360°) and so on. The invention is not limited to any particular infeed  26  to discharge  28  configuration.  
         [0026]     The spiral freezer  20  comprises a continuous conveyor  24 , spaced portions of which are shown by  FIG. 1 . That is, a small section of conveyor  24  is in view at an infeed station  26 , another like small section of conveyor  24  is in view at the discharge station  28 . As better shown by  FIG. 2 , the conveyor  24  provides a continuous food-carrying run  30  between the infeed and discharge stations  26  and  28 . The continuous run  30  of the conveyor  24  spirals up from the low infeed station  26  to the high discharge station  28 . Although this is not shown by the drawings, food product can be originally introduced onto the infeed section  26  by a conventional transfer arrangement from an upline conveyor or the like, as is known in the art. Similarly, food product can be discharged onto downline conveyors by conventional transfer arrangements or the like as is also known in the art.  
         [0027]     While this too is not shown by the drawings, the discharge and infeed sections  28  and  26  of the continuous conveyor are linked together by a return run of the conveyor. Persons having ordinary skill in the art can readily construct such an arrangement of a return run, which return run is preferably situated entirely or predominantly outside of the cylindrical enclosure  22 , an example of a suitable arrangement of a return run being shown by the above-referenced companion U.S. patent application Ser. No. ______ *[not yet known, to be inserted by applicant&#39;s attorney], filed on even date herewith.  
         [0028]     The food-carrying conveyor  24  preferably takes the form of, for example and without limitation, a woven wire mesh belt as shown by U.S. Pat. No. 6,305,274—Nothum (or as more particularly shown by  FIG. 6  thereof). Woven wire mesh belts such as that are advantageously formed into endless conveyors such as here. These woven wire belts are desirable for many reasons. Among them, these belts provide greater than 85% open area. This allows fairly unrestricted frigid air circulation to get at the food product. This also facilitates wash down and inspection. They are lightweight and don&#39;t demand much drive power. Also, they turn tight circumferences around small transfer rollers to ensure gentle handling and smooth transfer of various products. These belts can be produced in about any width, with commercially available sources providing standardized widths available off-the-shelf as anywhere between about four inches (0.1 m) and twelve feet (3.7 m). Needless to say, these belts can be produced in indefinitely long lengths.  
         [0029]      FIG. 2  of the drawings shows that the conveyor  24  in accordance with the invention further comprises a series of longitudinally spaced flights  40  fixed to the conveyor  24 , preferably with a uniform spacing therebetween.  FIG. 4  shows one such flight  40  in better detail. To turn to  FIG. 4 , it shows a transverse-section cut of the conveyor  24  as provided with a transverse flight  40  sitting on the conveyor  24 &#39;s main food-carrying run  30 . The flight  40  has mounted to it four rollers  42 / 44 . Two such rollers  42  are mounted for riding along the top of the conveyor-carrying surface  50 , which will be more particularly described below. Two other rollers  44  are mounted for tracking against the opposite lateral sides of the conveyor-carrying assembly  50  as shown. The rollers  42 / 44  cooperate to reduce the sliding resistance to the conveyor  24  that for the most part scrapes along the given conveyor-carrying surface  50  as well as maintain tracking therefor. The flight  40  extends between relatively inboard and outboard ends  46  and  48 . The outboard end  48  terminates with the mounting of the outboard tracking-roller  44 . The inboard end  46  is constructed as an overhang section that overhangs the inboard tracking-roller  44 . The operative advantages of the inboard overhang  46  are more particularly described below in connection with driving the conveyor  24  up its spiral ramp  50 .  
         [0030]     Returning to  FIG. 2 , the conveyor  24 &#39;s main food-carrying run  30  scrapes on top of a spiral ramp  50 . The spiral ramp  50  is continuous between the infeed station  26  through to the discharge station  28 .  FIGS. 2 and 4  taken together show that this spiral ramp  50  is produced from a series of tube coils  52  helically wound as shown. The ramp  50  can be reckoned as a helical ribbon. The individual tubes  52  occupy set lanes within the helical ribbon defined by the tube assembly  50  as a whole. Preferably the tubes  52  are rectangular tubes as shown in  FIG. 4  in transverse section. Preferably, the rectangular tubes  52  are arranged side by side such that the broad side of one is spaced by a gap from the broad side of another. The tubes  52  are hence stood on their narrow sides. The gaps increase the heat sink surface area and thereby enhance the efficiency of refrigerating the air, and ultimately pulling warmth out of the warm or room-temperature food product. The top narrow sides are arranged on a uniform level to present a smooth spiral ramp (eg.,  50 ) or scrape surface for the main spiraling food-carrying run  30  of the conveyor  24 .  
         [0031]      FIGS. 1 and 2  show that the enclosure  22  comprises a closed cylinder having insulated walls. The enclosure  22  is provided with infeed and discharge openings  60  and  62  for the introduction and discharge of the conveyor  24  respectively. The enclosure  22  has a floor  64  on which stands a squat stand  66 . The squat stand  66  has a set of short legs arranged in a circle to prop up a circular track  68 .  FIG. 2  (among others) shows that the hollow interior of the spiral ramp  50  is occupied by a large turning barrel  70  stood on an end. The barrel  70  has a bottom end carrying a series of rollers  72  to ride in the circular track  68  of the squat stand  66 .  FIG. 5  shows that the barrel  70  has a top end carrying a like series of rollers  72  to ride in a hoop track  68  that is suspended from the enclosure  22 &#39;s ceiling. Returning to  FIG. 2 , the squat stand  66  props up the barrel  70  some spacing off the floor  64  of the enclosure. The rollers  72  riding in the circular track  68  allow the barrel  70  to revolve about the vertical central axis. The bottom rim of the barrel  70  is formed with gear teeth such that the barrel  70 &#39;s bottom rim takes the form of a ring gear  74 , which can be alternatively described as a face gear  74 .  FIG. 3  shows that at least one or more electric motors  80  are mounted outside the enclosure for supplying drive power to the barrel  70 . The electric motor  80  turns a drive shaft  82  which extends in through a journal or bearing in the enclosure  22 &#39;s sidewall and which is supported or braced from or to the squat stand  66  by a gudgeon or the like, to terminate in a pinion  84  aligned to mesh with the barrel  70 &#39;s face gear  74 . Hence turning the drive shaft  82  turns the pinion  84  which in turn causes the barrel  70  to revolve on top of the squat stand  66 &#39;s ring track  68 .  
         [0032]     Any of  FIGS. 2, 3  or  6  among others, show that the barrel  70  has an outer wall or skin  76  that is striped with a series of paddles  78 . The exterior paddles  78  project out sufficiently to catch and drive against the inboard overhangs  46  of the conveyor  24 &#39;s flights  40 . Hence the conveyor  24  is motivated up the spiral ramp  50  in this fashion. The turning barrel  70  has the paddles  78  revolving in unison with the barrel  70 &#39;s skin  76 . The infeed section  26  of the conveyor  24  is fed to the barrel  70  along a tangent of the barrel&#39;s skin  76 . The tangential course of the infeed section  26  is aligned such that the inboard overhang  46  approaches so as to just nearly touch the barrel  70 &#39;s skin  76 . While this is happening, then along comes one of the vertical paddles  78  on the barrel  70 &#39;s skin  76  and smacks up against the inboard end  46  of the conveyor  24 &#39;s flight  40 . The vertical paddle  78  drives the flight  40  such that the entire conveyor  24  is motivated to advance or traverse forwardly on the spiral ramp  50  in consequence. Indeed, this action between barrel paddles  78  and conveyor flights  40  occurs in endless succession so that at any one instance, there are numerous flights  40  being driven by the several paddles  78 . For example,  FIG. 3  shows that the barrel  70  has about eight (8) paddles  78  angularly spaced evenly from each other. The conveyor  24 &#39;s flights  40  are spaced correspondingly such that for each 360° around one helical coil there are eight (8) flights  40  in driven contact with the eight (8) paddles  78 . If it is reckoned in  FIG. 2  that there are about 4¼ helical coils, then there are about thirty-four (34) concurrent instances of paddle-to-flight contact (ie.,  78 -to- 40  contact). In this way the turning barrel  70  supplies drive power to the conveyor  24 .  
         [0033]      FIG. 4  shows one example instance of paddle-to-flight contact (ie.,  78 -to- 40  contact). The revolving paddle  78 —revolving because the barrel skin  76  to which it is attached is revolving—pushes against the flight  40  to motivate the flight  40  and the woven wire mesh belt sections between spaced flights  40  to move in the direction of advance up the helical ramp  50 . As this flight  40  winds its way around the helical coils of the ramp  50 , it slides vertically up the paddle  78  at the same time. When this given flight  40  first contacts the paddle  78  at the infeed station  26 , it hits the paddle  78  near the lower end thereof. In contrast, when this given flight  40  separates from the paddle  78  on a tangential exit line at the discharge station  28 , the flight  40  does so from the upper end of that paddle  78 . Hence all the time the flight  40  is pushed by the paddle  78  it is slowly sliding upwardly too.  FIG. 4  also shows the cooperation of the inboard and outboard tracking-rollers  44  in preventing the flight  40  from deflecting off the paddle  78 .  
         [0034]     To return to the matter of the series of tubes  52  that comprise the ramp  50 , the tubes  52  are hollow and inside thereof flows the refrigerant.  FIGS. 1 and 2  show a supply header  54  at the infeed station  26  providing a pumped input of refrigerant from the refrigerant source  90 , as well as showing an exhaust header  56  at the discharge station  28  for returning the refrigerant to the refrigerant source  90  for re-processing and recycling through the coils of tubes  52 . Thermal-fluid or -medium supply and exhaust headers  54  and  56  are more particularly shown and described in the above-referenced U.S. Pat. No. 6,305,274—Nothum, which is incorporated herein by this reference to it. The conveyor  24 &#39;s woven wire mesh preferably scrapes immediately on top of the tubes  52  to close up the spacing between the food product and the heat sink capacitance of tubes  52  as much as shown in  FIG. 4  for example.  FIG. 3  shows a fan  94  disposed in the top end of the barrel  70  for circulating the interior air within the enclosure  22 .  FIG. 4  shows that the air is circulated such that it blows up through the gaps between the individual tubes  52  (and indicated by air circulation reference arrows  96 ).  FIG. 2  shows that the overall air circulation pattern is like a donut skin rotating inside and out as shown without actually orbiting the vertical central axis. It is an advantage to prop up the barrel  70  by the squat stand  66  to allow an underflow of circulating air.  FIG. 2  also shows that the barrel  70 &#39;s upper edge is gapped way from the enclosure  22 &#39;s ceiling to likewise allow an overflow as desired.  
         [0035]     Given the foregoing, the advantages of the invention include the following. The enclosure  22  that houses the spiral freezer  20 &#39;s spiral ramp  50  is shrunk down to the size of approximately the same as the outside of the spiral freezer ramp  50 . The barrel  70  provides an advantageous way of driving the conveyor  24 , as from impermanent interfacing with the conveyor  24  from spaced inboard projections  46 . The barrel  70 &#39;s skin  76  also blocks the inboard side of the freezer ramp  50  so that air circulation can be forced in the donut skin shape shown by  FIG. 2 . Along with this, the barrel  70  is propped up off the enclosure  22 &#39;s floor to allow an underflow as well as gapped from the enclosure  22 &#39;s ceiling to allow an overflow. The ramp surface  50  is produced as a series of coiled tubes  52  in which flow the refrigerant. That way the transfer of heat from the food product into the refrigerant occurs in as close as proximity as shown by the drawings. Also, the electric drive motor  80  for the barrel  70  is positioned outside the enclosure  22 &#39;s confines. Likewise the electric motor drive for the air circulation fan  94  is thermally isolated from the freezer compartment defined by the enclosure. Placing the electric drive motors  80  and the like outside of the freezer compartment (eg.,  22 ) avoids waste heat being dumped inside the freeze compartment (eg.  22 ), which is more energy efficient and therefore saves energy costs.  
         [0036]     Optionally the refrigerant source  90  comprises a conventional refrigerant circulating system comprising either a convention vapor compression-cycle machine having a closed loop refrigerant cycled through a compressor, a condenser, an expansion process, and then an evaporator before returning to the compressor (not shown). The refrigerant source  90  might be configured in other forms including absorption-cycle machines or heat pipes and the like. Regardless, the inventive aspect of the heat exchanger ramp  50  and freezer compartment (eg.,  22 ) in connection with the present invention include that the heat-producing components of the refrigerant source  90  can be located outside the freezer compartment (eg.,  22 ). That way, any of the refrigerant source  90 &#39;s heat issuing components such as compressors, pumps, motors, or condensers and the like are collectively disposed outside of the freezer compartment (eg.,  22 ) in order to maximize energy efficiency. At least that is, by avoiding waste by locating hot components inside the freezer compartment (eg.,  22 ).  
         [0037]     Further advantages of the invention include that this configuration is amenable to zoning. That is, intermediate exhaust and supply headers (eg., like  56  and  54 ) can be connected at an intermediate elevation with the helical assembly  50  of tubes  52  (this is not shown). Hence the set of tubes  52  in the zone defined below the intermediate elevation might be supplied refrigerant at one given temperature while the set of tubes  52  in the zone defined above the intermediate elevation might be supplied colder refrigerant or vice versa. That way, a user can establish not only a cold lower zone but then also an even colder upper zone. The barrel  70  might be comparably altered for zoning as by providing it with a gap in its waist. A horizontal circular plate at the waist as well as incorporation of an additional air fan (eg., like  94 ) in the lower zone can set up separate upper and lower donut patterns of air circulation. Preferably the barrel paddles  78  would reach across the barrel skin  76 &#39;s waist gap and tie together the upper and lower bands or hoops thereof (again, not illustrated).  
         [0038]     In the description, the term “spiral” and “helical” have been used generally interchangeably unless context dictates otherwise.  
         [0039]     The invention having been disclosed in connection with the foregoing variations and examples, additional variations will now be apparent to persons skilled in the art. The invention is not intended to be limited to the variations specifically mentioned, and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples, to assess the scope of the invention in which exclusive rights are claimed.