US 3813895 A
Apparatus for continuous cooling of articles comprising an elongated tunnel having an endless conveyor for moving articles therethrough in an atmosphere of a cryogenic fluid. The tunnel is defined by a plurality of sections alternate ones of which have hinged top covers and downardly movable bottoms which may be opened to gain access to the interior of the tunnel to facilitate cleaning thereof. The conveyor and all of the fluid handling apparatus are carried by stationary, non-openable sections of the tunnel which are disposed between the alternate openable sections. Also disclosed is a pivotable arcuate baffle for directing cryogenic fluid toward the article inlet end of the tunnel.
Description (OCR text may contain errors)
O Unite States Ptent 1  3,813,895
Klee et al. 1 June 4, 1974 FOOD FREEZING APPARATUS Primary Examiner-Meyer Perlin Assistant Examiner-Ronald C. Capossela  Inventors gig fl' fiigzf ggi z kg Attorney, Agent, or Firm--Rona1d B. Sherer; Barry Moyerman  Assignee: Air Products and Chemicals, Inc.,
Allentown, Pa. 57 ABSTRACT  Filed: Sept. 28, 1972 Apparatus for continuous cooling of articles comprising an elongated tunnel having an endless conveyor [21 1 Appl' 292869 for moving articles therethrough in an atmosphere of a cryogenic fluid. The tunnel is defined by a plurality of  U.S. Cl 62/266, 62/303, 62/374, Sections lternate ones of which have hinged top cov- 198/229, 134/200 ers and downardly movable bottoms which may be  Int. Cl. F25d 23/02 pene o gain ccess to the interior of the tunnel to  Field of Search 62/303, 302, 63, 3745, facilitate cleaning thereof. The conveyor and all of the  References Cited UNITED STATES PATENTS 3,580,000 5/1971 Wagner 62/77 3,583,171 6/1971 Flynn et a1 62/303 X 19 Claims, 5 Drawing Figures PATENTEDJux 41974 SHEEI 1 ll 3 2% @m SN FOOD FREEZING APPARATUS This invention relates broadly to the refrigeration art, and more particularly to the freezing of articles such as food and the like in a continuous cryogenic system. Still more specifically, this invention relates to an improved freezing apparatus having features which facilitate the cleaning thereof in a manner superior to those taught by the prior art.
Apparatus for continuous cooling and freezing of articles, particularly of food and the like, are well known in the art as exemplified by U.S. Pat. No. 3,403,527, issued Oct. l, 1968, and assigned to the assignee of this invention. Such apparatus usually includes an elongated tunnel defined by insulated walls and an endless conveyor belt extending longitudinally of the tunnel for moving articles therethrough. A cryogenic fluid, such as liquid nitrogen, may be introduced as a spray into the tunnel, usually near the exit end thereof, and induced to move through the tunnel as a vaporized gas in counterflow relation to the movement of articles therethrough and in a plurality of recirculation zones. The gas may then be exhausted from the tunnel near the inlet end thereof.
in the use of such apparatus, crumbs and particles of food are frequently broken off of the food articles being moved through the tunnel and remain in the interstices of the conveyor belt, or fall through the belt onto the bottom of the tunnel. Such particles, of course, if permitted to remain in the apparatus, will become spoiled and may contaminate fresh food passing therethrough. Consequently, it is imperative that means be provided to facilitate cleaning of such apparatus so as to meet U.S.D.A. standards, as well as to facilitate inspection thereof by USDA. officials.
The construction of such prior art apparatus, however, inherently hindered the attainment of these objectives. This was caused primarily by the fact that the tunnels had to be hermetically sealed along their lengths which rendered disassembly thereof for cleaning difficult. Moreover, the length of the tunnels, often over 50 feet long, frustrated effective hosing down from end to end.
Consequently, adequate cleaning ordinarily required substantial dismantling of the apparatus including removal of the conveyor belt and related parts. Obviously, such procedure is time-consuming and requires undue downtime for cleaning.
Several attempts have been made by the prior art to overcome this problem. In US. Pat. No. 3,431,745, issued Mar. 1 l, 1969, to J. D. Harper et al, there is disclosed a cooling apparatus in which the conveyor can be moved out of the tunnel through one end thereof so that both the conveyor and the interior of the tunnel can be hosed down for cleaning. This system is generally satisfactory for tunnels and conveyors up to about 30 feet in length but becomes impractical with longer apparatus because there may be inadequate floor space to accommodate removal of the conveyor. Moreover, hosing down of long tunnels is usually ineffective because the force of the water stream may decrease sufficiently before reaching the end of the tunnel such that the food particles may be redeposited therein before being swept away.
In US. Pat No. 3,583,171, issued June 8, l97l, to C. M. Flynn and D. .l. Klee, there is disclosed a cooling apparatus including a tunnel having hinged covers and bottom sections with removable two-foot plugs for gaining access to the interior of the tunnel. The majority of contamination collected on the interior horizontal surface of the bottom sections and cleaning of this area was difficult because the cleaning water stream had to be forced through two layers of the conveyor belt. Moreover, inspection of this area was even more difficult because the intervening upper and lower reaches of the conveyor belt restricted the view of the tunnel interior.
Another attempt to overcome the problem of cleaning elongated continuous cooling apparatus is described in US. Pat. No. 3,580,000, issued May 25, I971, to R. C. Wagner. This patent discloses a cooling tunnel having a plurality of sections with hinged covers and deep U-shaped bottom sections. During cleaning, the adjacent sections may be moved horizontally apart and the entire conveyor belt and its supporting structure lifted out of the bottom sections by a jack system. Inasmuch as the conveyor belt is lifted only a few inches above the bottom sections, cleaning and inspection of the interior of the tunnel is still difficult. Furthermore, the disassembly procedure is very complex, time consuming, and subject to human error.
It is, therefore, a primary object of this invention to provide a continuous cooling apparatus having novel features of construction which facilitate rapid and effective cleaning thereof. I
Another object of this invention is to provide an apparatus for the continuous cooling of food and the like, which apparatus may be readily cleaned and thoroughly inspected to meet government sanitation standards.
More particularly, it is an object of this invention to provide a continuous cooling apparatus including an elongated tunnel having an endless conveyor belt extending longitudinally thereof for moving articles through the tunnel to be cooled, whereinmeans are provided for rapidly and easily gaining complete access to the interior of the tunnel for cleaning the conveyor belt and all of the interior surfaces of the tunnel.
Another object of this invention is to provide a continuous cooling apparatus as above-described wherein the tunnel is defined by a series of alternate movable and stationary sections, and wherein the conveyor belt and all of the fluid handling apparatus are carried by the stationary, non-openable sections while the movable sections are free to be completely opened to gain access to the entire interior of the tunnel,
A further object of this invention is to provide apparatus as above-described wherein the movable sections include back-to-back hinged top covers that may be pivotably opened and bottom portions underlying the conveyor that may be moved downwardly thereby completely exposing the interior surfaces of all of the sections of the tunnel.
Yet another object of this invention is to provide a continuous cooling apparatus as above-described wherein thecooling fluid is introduced as a spray into the tunnel nearthe article exit end thereof and the va porized gas is induced to move through the tunnel in counterflow relation to the, direction of movement of articles therethrough solely by means of radial fans mounted in the stationary sections of the tunnel, and wherein a pivotable arcuate baffle may be provided in association with at least one of the radial fans for directing gases emitting from the fan in counterflow relation to the direction of movement of articles through the tunnel.
Briefly, these and other objects that may become hereinafter apparent are accomplished by providing a cooling tunnel defined by a plurality of adjacent sections disposed in end-to-end relation along the length thereof. Every other one of the adjacent sections is formed of a pair of back-to-back hinged top covers and a cooperating bottom which underlies the conveyor belt extending through the tunnel. The top covers include depending side walls which sealingly mesh with the bottom in the closed condition of the tunnel. When it is desired to clean or inspect the interior of the tunnel, the hinged top covers are pivotably opened and the bottoms are lowered by means of jacks to completely expose the conveyor belt and the entire-interior of the tunnel; such sections being referred to as movable or openable tunnel sections.
Disposed between each of the above-described openable sections is a relatively shorter stationary or fixed section upon which are solely mounted the supports for the conveyor belt as well as all of the fluid handling apparatus for the system, including the cooling fluid inlet and outlet means, the radial fans for inducing movement of the fluid through the tunnel, flow directing bafflesfand temperature monitoring and control instruments. Consequently, while the stationary sections of the tunnel do not open in the manner that the openable or movable sections open, the fact that they carry or support all of the structural and operational features of the apparatus enables the movable sections to open sufficiently to completely expose not only their own interior surfaces, but the interior surfaces of the adjacent short stationary sections as well, thereby permitting complete access to the conveyor belt and all of the interior surfaces of the tunnel for cleaning and inspection; the stationary or fixed tunnel sections also being referred to as non-openable sections.
With the above and other objects in view that may become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the figures illustrated in the accompanying drawings, the following detailed description thereof, and the appended claimed subject matter.
IN THE DRAWINGS FIG. I is a broken schematic elevation view having parts cut away for clarity of continuous cooling apparatus constructed in accordance with this invention, and illustrates a tunnel defined by a series of alternate movable and stationary sections and having a conveyor belt extending therethrough, the stationary sections shown supporting cooling fluid inlet means, outlet means and flow-inducing radial fans, the movable sections having top covers in the down position and bottom portions in the up position, the bottom portions being supported on jack-actuated frame members;
FIG. 2 is an enlarged vertical sectional view taken along line 2-2 of FIG. 1, and illustrates in phantom a movable section in the open position, the hinged top covers being pivoted upwardly and the bottom portion being lowered substantially beneath the lower reach of the endless conveyor belt;
FIG. 3 is a fragmentary perspective view of the inter ior of a stationary section, and illustrates details of the conveyor belt supports mounted on the stationary sec tion;
FIG. 4 is a fragmentary perspective view of a radial fan mounted in the top of a stationary section as shown in phantom, and illustrates a motor-operated pivotable arcuate baffle disposed adjacent the periphery of the fan for directing the gas toward the inlet of the tunnel; and
FIG. 5 is a fragmentary perspective view of a movable section of the tunnel, and illustrates the hinged top covers pivoted open and the bottom portion lowered to completely expose the conveyor belt and the interior surfaces of the section, as well as the interior surfaces of the adjacent stationary sections.
Referring now to the drawings in detail, there is illustrated in FIG. 1 a continuous cooling apparatus constructed in accordance with this invention and generally designated by the numeral 10. The apparatus includes a frame 12 having legs 13, longitudinally extending box beams l4, 15 (FIGS. 1 and 2), and lateral supports 16 extending between the box beams l4, 15.
The frame 12 supports an elongated tunnel 17 defined by a series of alternate movable or openable sections 18 and short stationary or non-openable sections 19. For reasons which will become apparent, it has been determined that the fixed sections should be as short as possible. For example, the length of the fixed sections should be within the maximum range of 4 to 18 inches, and preferably within the optimum range of 10 to 15 inches, or 10 to 30 percent of the length of the movable sections. Thestationary sections 19 are each supported by a pair of vertical support posts'20, 21 which extend upwardly from the box beams l4, 15, respectively. The movable bottom portions 49 of sections 18 are supported by angle frame assemblies 22 which extend beneath the movable sections 18 and are in turn supported by lifting screws 23 of conventional jacks 24 which are mounted on the lateral supports 16. Each angle frame assembly 22 may extend beneath from two to five movable bottom portion of sections 18 and cooperates with four of the lifting screws 23 and jacks 24 to vertically move the bottom portions of the movable sections 18 as will be hereinafter more fully explained.
The apparatus 10 also includes a mesh conveyor belt 25 which extends through the tunnel l7 and has upper and lower reaches 26, 27, respectively. The belt 25 extends over pulleys 28, 29, at the inlet end of the tunnel 17 (left side as viewed in FIG. 1), and over a pulley 31 at the outlet end of the tunnel 17 (right side as viewed in FIG. 1). The belt 25 is driven by means of a motor 32 through a drive chain and sprocket arrangement (not shown). Food or like articles intended to be conveyed through the tunnel 17 for processing are placed on the conveyor belt 25 at a loading table portion thereof 33 (FIGS. 1 and 5).
A cryogenic fluid such as liquid nitrogen is admitted to the interior of the tunnel 17 through a supply line 34 which communicates with a spray header 35 mounted in a stationary section 19 disposed near the exit end of the tunnel 17. The liquid nitrogen may be emitted through spray nozzles 36 directly on the articles moving through the tunnel l7 whereupon it will vaporize and become a gas. The gas is forced to move in a plurality of recirculating paths by the effect of radial fans 37 which may be mounted in one or more of the stationary sections 19. The structure and operation of the fans 37 are more fully explained in the above-noted US. Pat.
No. 3,403,527. The fans 37 are driven by motors 38 also mounted on the stationary sections 19. Transverse zone baffles 39 depend downwardly from the upper portions of the movable sections 18 on each side of the fans 37 to define cooling zones therebetween while permitting some of the gasto pass underneath into the adjacent upstream zone in cascading fashion. Anti-swirl vanes 40 may be provided for inhibiting swirling action of the gas around the fans 37. Rather than having the gas spill into the room, the gas is preferably removed from the tunnel 17 by means of an exhaust duct 41, mounted in the first stationary section 19, and a remote blower 42 which has little or no effect on the actual movement of the gas through the tunnel I7. Thus, the blower 41 is primarily used for safety reasons, e.g., to preclude the build-up of non-life supporting nitrogen gas in the room in which the freezer and operating personnel are located.
Referring now particularly to FIG. 2, there are illustrated details of a movable or openable section l8. Each movable section 18 includes a pair of hinged top covers 43, 44 having upper portions 45-and depending side portions 46. The side portions 46 terminate in in clined surfaces 47 which sealingly mesh with correspondingly inclined surfaces 48 of a bottom portion 49 in the closed condition of the movable section 18. The bottom portion 49 is supported by and fastened to the angle frame assembly 22 whereby it may be moved downwardly away from the top covers 43, 44 by means of the jacks 24 as seen in phantom in FIG. 2, as well as in perspective in FIG. 5. A vertically disposed slide pin 50 extends downwardly from the angle frame assembly 22 and slidingly cooperates with a slide bushing 51 carried in one of the lateral supports 16 for preventing lateral movement of the bottom portion 49 during vertical movement thereof.
The jacks 24 are of conventional design and may be manually, electrically or pneumatically operated. A typical model jack may be the Duff-Norton Miniature 'Jactuator No. M2555 or M-2625.
The top covers 43, 44 are each carried by sleeves 52 which are keyed to torsion bars 53 which are, in turn, mounted in flanged support blocks 54 mounted on the stationary sections 19. The covers 43, 44 may be swung open approximately 80 degrees and counterbalanced in the open position by the torsion bars 53. The top covers 43, 44 further include handles 55 which facilitate manual opening and closing thereof. Toggle latch means 56 (FIG. 5) may be provided for securing the top covers 43, 44 in the closed position.
As seen most clearly in FIGS. 2 and 3, the upper reach 26 of the conveyor belt 25 is supported on plastic wear strips 57 mounted on lateral support bars 58 which, in turn, are carried by longitudinally extending side rails 59 supported by clips or brackets 60 mounted in the interior side walls of the stationary sections 19. The wear strips 57 can be formed of any suitable high molecular weight material capable of withstanding the low temperatures and providing the necessary antifriction function. For example, polytetrafluoroethylene (e.g., Teflon) can be satisfactorily employed. The lower reach 27 of the conveyor belt 25 is, on the other hand, supported on stainless steel bars 61 mounted on vertical support pins 62 extending upwardly through inclined sloping surfaces 63 of the bottom of the stationary member 19.
Referring now to FIG. 4, there is illustrated a radial fan 37 mounted in a stationary section 19 and having an arcuate baffle 64 disposed adjacent a portion of the periphery thereof. As seen more clearly in FIG. 1, the baffle is disposed on the downstream side of the fan 37 relative to the direction of movement of articles through the tunnel 17. The baffle 64 is mounted for pivotable movement toward and away from the periphery of the fan 37 on a rotatable shaft 65 which depends from the stationary section 19. The shaft 65 may be rotated by means of a motor 66 through a linkage consisting of slotted arms 67, 68 and a connecting link 69.
The arcuate baffle 64 is so positioned on the spray zone side of the fan 37 such that the net flow of the cold gas emitting from the periphery of the fan 37 is directed upstream toward the article inlet end of the tunnel 17 in counterflow relation to the direction of movement of articles therethrough, as indicated by the arrows F in FIG. 4. The motor 66 may be manually or automatically actuated in response to one or more of the operating parameters, such as the liquid nitrogen flow rate, to pivot the baffle 64 toward or away from the fan 37 thereby changing the net flow effect therefrom in accordance with particular temperature requirements.
Although the cooling apparatus 10 is specifically illustrated herein as having only one baffle 64, it is to be understood that additional baffles 64 may be utilized in association with additional fans 37 toward the article inlet end so as to achieve the desired result of inducing a net flow of the cooling fluid from the spray header 35 toward the exhaust duct 41 at the article inlet end of the tunnel 17. It has been found in accordance with this invention that this arrangement of radial fans 37 and arcuate baffles 64 removes the necessity of having a plurality of parallel flow sections with elongated ductwork as disclosed in the aforementioned U.S. Pat. No. 3,403,527.
As mentioned above, during normal operation of the apparatus 10 particles of food will tend to accumulate on the conveyor belt 25 and in the interior of the tunnel 17. It has been found that approximately percent of the contamination will deposit in the regions beneath the-conveyor belt 25. It should be readily apparent, therefore, that periodic inspection and cleaning is necessary to meet sanitation requirements. The inspection and cleaning of the apparatus 10 in accordance with this invention may be accomplished as follows:
After the apparatus 10 is shut down, the latch means 56 are unfastened and the hinged top covers 43, 44 then opened as illustrated in FIG. 5. The jacks 24 are then actuated to lower the bottom portions 49 of the movable sections 18, preferably about nine inches below the conveyor belt 25. The complete tunnel interior is then fully exposed and may be readily cleaned. The sloping inclined surfaces 63 of the bottom of the stationary sections 19 (FIG. 3), as well as the inclined surfaces 48 of the bottom portions 49 (FIG. 2), facilitate flushing of particles from the regions of the tunnel l7 underlying the belt 25. As clearly shown in FIG. 5, the raised covers 43, 44 and the lowered bottom portions 49 permit rapid and complete access to all portions of the interior of the tunnel 17, including the adjacent stationary sections 19.
In view of the foregoing, it should be readily apparent that there is provided in accordance with this invention an apparatus for continuous cooling of articles to low temperatures, particularly articles of food or the like,
wherein the articles are moved through an elongated tunnel by means of an endless conveyor belt for treatment by a cooling fluid, and wherein novel means are provided for rapidly and easily gaining complete access to the interior of the tunnel for inspecting and cleaning the same as well as the belt itself. The novel concept of providing a tunnel defined by a series of short, nonopenable stationary sections separated by movable, openable sections having hinged covers and lowerable bottoms, and wherein the stationary sections are of minimum length sufficient only to mount the conveyor belt frame and the fluid handling apparatus, permits a complete opening of the tunnel for inspection and cleaning.
it should be understood that while this invention has been specifically illustrated and described herein with reference only to a particular embodiment thereof, further minor modifications may be made therein without departing from the spirit of the invention as defined in the appended claimed subject matter. For example, while the specific tunnel 17 described herein is preferably approximately 2 feet in width, a wider 4 foot wide tunnel may be utilized with certain structural modifications. Specifically, the wider tunnel may accommodate two adjacent radial fans 37 in one or more of the stationary sections 19. Also, the angle frame assembly 22 may be eliminated and four jacks 24 utilized to raise and lower each larger bottom portion 49. Further, additional slide pins 50 may be used in association with each bottom portion 49 for greater stability.
1. Apparatus for continuous cooling of articles comprising an elongated tunnel defined by a plurality of alternate openable and stationary sections, conveyor means in said tunnel for moving articles longitudinally therethrough, means for applying cooling fluid to articles moving through said tunnel, means for inducing movement of said cooling fluid through said tunnel in generally counterflow relation to the direction of movement of articles moving through said tunnel, means carried solely by said plurality of stationary sections for supporting said conveyor means within said tunnel, and means for opening said openable sections whereby complete access may be had to all of said sections of said tunnel without moving said conveyor means relative to said stationary sections.
2. Apparatus as defined in claim 1 wherein said means for inducing movement of said cooling fluid are supported by at least one of said stationary sections.
3. Apparatus as defined in claim 1 wherein said means for applying cooling fluid are supported by at least one of said stationary sections.
4. Apparatus as defined in claim 1 wherein said plurality of stationary sections have a length within the range of four to eighteen inches.
5. Apparatus as defined in claim 1 wherein said conveyor means includes an endless belt having upper and lower reaches extending through said tunnel, and wherein said means carried solely by said stationary sections for supporting said conveyor means includes plastic wear strips extending longitudinally of said tunnel and carried by lateral support bars mounted on side rails affixed to brackets mounted in said stationary sections.
6. Apparatus as defined in claim 1 wherein said openable sections include a top, depending side wall portions and a bottom, and wherein said top and depending side wall portions define a pair of hinged covers 7. Apparatus as defined in claim 6 wherein said hinged covers are disposed back-to-back and are pivotably journaled in blocks carried by said stationary sections.
8. Apparatus as defined in claim 6 wherein said bottom includes longitudinally extending inclined surfaces for facilitating removal of particles from the interior of said tunnel, and wherein said inclined surfaces mesh with correspondingly inclined surfaces on said depending side wall portions of said covers for sealing said movable sections in the closed condition thereof.
9. Apparatus as defined in claim 6 wherein said bottom is adapted to open downwardly away from said covers.
10. Apparatus as defined in claim 9 including jack means for moving said bottom vertically towards and away from said covers.
11. Apparatus as defined in claim 10 including a frame structure extending under a plurality of said sections and actuated by said jack means whereby a plurality of said bottoms may be moved in unison by a set of said jack means.
12. Apparatus as defined in claim 1 wherein said means for inducing movement of said cooling fluid is a radial fan mounted in at least one of said stationary sections and disposed in spaced overlying relation to said conveyor means, and including an arcuate baffle disposed adjacent said fan on the downstream side thereof relative to the direction of movement of articles through said tunnel, whereby the net flow of the cooling fluid emitting from said fan is directed upstream in counterflow relation to the direction of movement of articles through said tunnel.
13. Apparatus as defined in claim 12 wherein said arcuate baffle is pivotable toward and away from the periphery of said fan.
14. Apparatus as defined in claim 13 including means for moving said baffle toward and away from the pe-' riphery of said fan in response to variations .in an operating parameter of the tunnel.
15. A food treating apparatus comprising an openended tunnel defined by a plurality of discrete adjacent sections disposed in end-to-end relation along the length thereof, endless conveyor means in said tunnel for moving food articles therethrough, means for applying cooling fluid to the articles on said conveyor, means for inducing movement of said cooling fluid through said tunnel generally counterflow relation to the direction of movement of the articles on said conveyor, alternate ones of said laterally adjacent sections having hinged covers and downwardly movable bottoms adapted to open for completely exposing the interiors of said sections, said alternate ones of said sections being separated by fixed non-openable sections, means carried solely by said fixed non-openable sections for supporting said endless conveyor means within said tunnel, said means for applying cooling fluid being mounted in at least one of said fixed non-openable sections, said means for inducing movement being mounted in at least one of said fixed non-openable sections, and means for opening said alternate ones of said laterally adjacent sections for completely exposing the interiors thereof as well as the interiors of said adjacent fixed non-openable sections so as to facilitate the cleaning of the interior of the entire tunnel.
16. An elongated tunnel for continuous cooling of articles passing therethrough comprising:
a. frame means,
b. a plurality of insulated tunnel sections rigidly fixed to said frame at spaced locations,
c. a plurality of openable insulated tunnel sections disposed between said fixed tunnel sections; said fixed and openable tunnel sections being in fixed endwise engagement with each other to form said elongated tunnel,
d. said openable tunnel sections including movable top and bottom portions,
c. said movable top portions being supported by hinge means having first portions rigidly secured to said movable top portions and second portions rigidly secured to said fixed tunnel sections,
f. adjustable means connected to said frame means and supporting said movable bottom portions for lowering said bottom portions downwardly away from said top portions, and
g. said fixed tunnel sections being sufficiently shorter in length than said openable tunnel sections such that said openable tunnel sections provide complete access to all interior tunnel portions of said entire elongated cooling tunnel in their open positions.
l7. The elongated cooling tunnel as claimed in claim 16 wherein said hinge means comprise torsion bar means assisting in lifting and holding said movable top portions in their open positions.
18. The elongated cooling tunnel as claimed in claim 16 including:
a. conveyor means extending through said elongated tunnel, and
b. conveyor support means connected solely to said fixed tunnel sections.
19. The elongated cooling tunnel as claimed in claim 16 including:
a. cryogenic fluid injection means mounted on at least one fixed section,
b. a plurality of motor and fan means for circulating said cryogenic fluid in contact with articles passing through said elongated tunnel; and
c. means mounting said motor and fan means on a plurality of said fixed tunnel sections.