Apparatus For Refrigerating Articles

Abstract

An apparatus for refrigerating, either freezing or chilling, articles and particularly food items including an insulated chamber having an entrance and an exit through which the articles are passed, apparatus for introducing a fluid cryogen in the form of vaporizable solid particles and gaseous fluid, the cryogen being for example carbon dioxide, and apparatus in the chamber for vaporizing any of the cryogen solid particles that might remain on the articles prior to the articles leaving the chamber. The disclosure also includes gas collecting and gas disposing device for disposing of cryogen gas externally of the apparatus in order to prevent excessive build-up of the gas in the ambient atmosphere surrounding the apparatus, the maximum amount of gas being thereby limited to about 5,000 parts of gas per million parts of ambient atmosphere, by weight.

Description

BACKGROUND OF THE INVENTION

This invention relates to apparatus for the refrigerating of articles or products employing a fluid cryogen which is in the form of flowable vaporizable particles and gaseous fluid in which some of the particles are deposited on the articles during their passage through an insulated chamber.

The most pertinent prior art of which applicant is aware are U.S. Pat. Nos. 3,214,928; 3,254,506; 3,403,527; 3,580,000; and 3,600,901. The present invention has features and advantages that are not disclosed in this or any other prior art of which applicant is aware.

SUMMARY OF THE INVENTION

In general the apparatus of this invention refrigerates articles such as food products by a combination of solid cryogen and gaseous cryogen with a portion of the gas being recirculated in countercurrent flow relationship to the articles conveyed through an insulated chamber and with means being provided for insuring that substantially all of the solid cryogen is vaporized from the articles before the articles pass from the chamber. The invention also includes means for controlling and disposing of the cryogen gas after the freezing of the articles so that the ambient atmosphere surrounding the apparatus has no more than 5,000 parts per million by weight of gas emerging from the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an apparatus embodying the invention.

FIG. 2 is a side elevational view of the apparatus.

FIG. 3 is an end elevational view taken from the right end of FIGS. 1 or 2.

FIG. 4 is a horizontal sectional view taken through the elongated chamber or tunnel of the apparatus.

FIG. 5 is a vertical longitudinal sectional view of the apparatus taken through the length of the apparatus.

FIG. 6 is an enlarged fragmentary sectional view of the portion of the apparatus where the fluid cryogen is introduced into the chamber.

FIG. 7 is a slightly reduced sectional view taken along line 7--7 of FIG. 6.

FIG. 8 is a fragmentary reduced view along line 8--8 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the embodiment of the apparatus 10 disclosed in the accompanying drawings there is provided an elongated thermally isolated chamber or tunnel 11 comprising a series of end-to-end subchambers 12, 13, 14, 15, 16 and 17 each with thermally insulated walls as shown in FIGS. 4 and 5 and insulated hinged lids 18 of generally the same type as disclosed in my prior U.S. Pat. No. 3,580,000.

As shown most clearly in FIG. 3 each of these lids 18 can be raised for servicing and cleaning the interior of the tunnel 11 as by operating the corresponding pressurized hydraulic fluid piston and cylinder structures 18a that are mounted on the side of the tunnel 11.

The insulated tunnel 11 has an entrance end 19 and an exit end 20 for the passage of articles through the chamber or tunnel and during which they are refrigerated by the fluid cryogen. This refrigerating may be either freezing or chilling at an above freezing temperature, as desired. Means are provided in the chamber 11 for passing the articles therethrough and as illustrated this means comprises an endless open metal conveyor 21 of the type disclosed in my above prior U.S. Pat. No. 3,580,000. The entrance end of the conveyor 21 extends beyond the chamber entrance 19 as indicated at 22 for ease in placing the articles 23 on the conveyor for passage through the chamber.

The apparatus of this invention utilizes a cryogen that exists principally in the form of gas and flowable finely divided solid and with the cryogen also capable of existing briefly in the form of a liquid. The term "cryogen" is used herein in the broadest sense as defined in Webster's New International Dictionary.

In the apparatus of this invention the means for introducing the fluid cryogen provides the material in the form of finely divided solid particles or snow and gas. In fact liquid carbon dioxide exists in the apparatus only very briefly if at all and does not come in contact with the articles moving through the apparatus in any material amounts.

The means for introducing the fluid cryogen specifically disclosed comprises a liquid carbon dioxide input line 24 and a carbon dioxide gas recirculation blower 25 operated by an electric motor 26 operating by way of shafts 63 and 64 and an interconnecting drive in housing 65. The liquid carbon dioxide from the input line 24 is supplied as needed through an air operated valve 27 operated by a valve positioner 28. The CO.sub.2 supply to the valve 27 is through an on-off valve 62.

As is illustrated in FIGS. 6 and 7 (and diagrammatically in FIG. 4) the liquid line 24 leads through valves 62 and 27 to a cryogen supply horn 29 that is positioned at the top of the gas recirculation blower housing 30. By the time the fluid cryogen leaves the exit 31 of the horn 29 it is in the form of a mixture of snow and gas so that the interior of the tunnel 11 is filled with the carbon dioxide gas and the traveling articles 23 are contacted by the snow. The snow sublimes to provide gaseous carbon dioxide atmosphere to the tunnel. No material amounts of liquid carbon dioxide leave the exit 31.

As shown most clearly in FIG. 4 the carbon dioxide snow and gas mixture leaves the blower 25 and enters the interior of the chamber 11 transversely to the direction 32 of movement of the conveyor 21 and the articles 23 carried thereby. In order to aid in distributing the fluid cryogen evenly throughout the full transverse area of the chamber 11 there are provided guide means in the form of spaced baffles 33 that extend from the exit 34 from the blower 25 through substantially 90.degree. and direct the fluid cryogen upstream or countercurrently to the movement 32 of the conveyor 21. This countercurrent and evenly distributed flow is indicated by the arrows 35 in FIG. 4. Thus the freshly introduced carbon dioxide is brought into initial contact with the conveyed articles to be refrigerated at an intermediate section 36 of the chamber between the entrance 19 and exit 20 ends thereof.

Upstream of the intermediate section 36 there is provided a cryogen gas recirculation zone 37 whose longitudinal extent is defined generally by a horizontal baffle 38 for the recirculation of the gaseous carbon dioxide. This baffle is below the conveyor 21 (FIG. 5) and has its downstream end 39 a short distance downstream from the fluid distribution baffles 33 and its upstream end 40 spaced from the entrance end 19 of the chamber.

Between the intermediate section 36 of the chamber 11 and the exit end 20 there are provided means for vaporizing any of the solid cryogen particles remaining on the traveling articles 23 before they reach the exit 20 from the freezing chamber. In the illustrated embodiment this vaporizing means includes a plurality of motor 41 operated fans 43 spaced along this section which is identified as a final sublimation zone 42 so that the top mounted fans 43 circulate the internal atmosphere transversely to the line of moving articles 23. The heat transfer from the articles themselves causes sublimation of solid CO.sub.2 on the articles. As a further aid in this subliming the transverse flow of atmosphere from the fans 43 is very effective. As a result, all solid CO.sub.2 particles on the articles are sublimed by the time the articles reach the exit 20.

The space 44 beneath the baffle 38 comprises a suction plenum chamber for the recirculation of the cold gas forwardly, or to the left, beneath the baffle 38, into the gas sump 50, through a transverse conduit 66, and back up into the blower 25 (FIGS. 4 and 5) for recirculation 35. Entrance to the sump is controlled by an adjustable manually controlled damper 68 and thereby controls the volume flow of recirculated gas.

There is provided a movable control damper 46 (FIG. 5) adjacent the top of the tunnel 11 and exits from the flow directing guides 33 with this damper being operated by a control motor 47. The two extreme positions of the damper 46 are shown in FIG. 5 in solid and dotted lines with maximum recirculation flow being achieved when the damper 46 is in its most elevated position while minimum recirculation flow results when it is in its downward position. The selected position of the balance control damper 46 is achieved automatically through the gas balance control 48 which is operated by a temperature sensor 49 at the exit end 20 of the chamber with the result that the control and the motor operated damper 46 limits the amount of carbon dioxide gas that passes out the exit end 20 of the system.

The gas balance control 47-49 functions in the same manner as the control in my prior U.S. Pat. No. 3,600,901, that is, under balanced conditions there is a slight excess of gas at the exit end 20 of the chamber 11 and it is this excess which spills over into the gas collector 53 (FIG. 5) to be pumped to a place of disposal.

The gas collecting sump 50 in the bottom of the chamber 11 contains a gas temperature sensor 51 which may be a thermocouple. This sensor 51 operating through a standard temperature control 52 regulates the amount of carbon dioxide passed into the system through valve 27 whose position is determined by the diaphragm type valve positioner 28.

The exit 20 of the chamber is provided with a gas collecting means in the form of a sump 53 into which the slight purge of heavier than air gaseous carbon dioxide collects and is pumped by means of a pumping means 54 and an outlet line 55 to a place of disposal. The entrance end 19 of the chamber to which most of the fluid gas is directed in countercurrent flow is provided with motor 67 operated exhaust blower 56 which exhausts the gaseous carbon dioxide through a line 57 to a place of disposal.

Because of the gas tight arrangement of the apparatus and the careful collecting and disposing of the cryogenic gas the atmosphere surrounding the apparatus never exceeds 5,000 parts of cryogenic gas per million parts of ambient atmosphere by weight. This is a very important safety feature as excessive carbon dioxide can be dangerous to workmen in reducing their oxygen supply. Carbon dioxide being heavier than air when spilled into a room builds up from the floor and can reach dangerous proportions without the workmen being aware of it in the absence of concentration indicating devices.

In the refrigerating system disclosed herein only a very small proportion of the cryogen fluid reaches the exit 20. In one example this amount is between 1 percent and 5 percent by weight and it is collected in the sump 53 and pumped to a place of disposal in the manner previously described. The remaining 95 percent to 99 percent is exhausted as gas from the system through the pump 56 and line 57. By the time the exhaust reaches the pump 56 the temperature in the case of carbon dioxide is at approximately 0.degree.F. As can be noted from FIGS. 4 and 5 the upstream end 40 of the recirculation baffle 38 is spaced downstream an appreciable distance from the entrance 19. The chamber section 58 between this end 40 and the exhaust pump 56 functions as a precooling zone 69 for incoming articles or product 23. A temperature barrier 70 is provided adjacent the exit 20.

As is apparent from the above the cryogen which is a mixture of snow and gas when introduced into the apparatus refrigerates both by the contact of the solid snow on the product when it rides along with it until sublimation and also by the low temperature of the cryogen gas. In the present invention full advantage is taken of these two actions because any of the snow falling between the articles, and this is particularly true of circular articles such as meat patties, is not wasted as it sublimes to a cold gas which contacts the articles.

This portion of the snow which falls through the conveyor and between the articles such as the meat patties accumulates beneath the conveyor and when the accumulation reaches the height of the conveyor is spread out in a uniform deposit by the moving conveyor which aids in the sublimation of the solid particles.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

Claims

I claim:

1. Apparatus for refrigerating articles, comprising: means defining a thermally isolated elongated chamber having an entrance and an exit for passage of said articles into, through and from said chamber; means for introducing a fluid cryogen including flowable vaporizable solid particles and gaseous fluid into contact with said articles at an intermediate section of said chamber between said entrance and exit during said passage, said means for introducing comprising guide means laterally spaced from each other across said chamber and having laterally adjacent exits spanning substantially the full width of said path of said articles for distributing said fluid substantially uniformly throughout said width; gas recirculation means comprising baffle means extending longitudinally of said chamber adjacent said path of articles, said baffle means extending from adjacent said guide means on the side thereof facing said chamber exit to adjacent but short of said chamber entrance, and blower means for recirculating said gas over said baffle means toward said chamber entrance and then beneath said baffle means back toward said chamber exit, said baffle means being spaced above the bottom of said chamber with the spaces above and beneath said baffle means serving as parts of a gas recirculation loop; and gas balance damper means for controlling the amount of gas in said recirculation loop, said damper means comprising a manual damper and a temperature responsive damper in series with each other and in spaced parts of said recirculation loop.

2. The apparatus of claim 1 wherein there is provided temperature control means in said recirculation loop for controlling the temperature within said chamber including a temperature sensing device in an external portion of said loop located externally of said chamber.

3. Apparatus for refrigerating articles, comprising: means defining a thermally isolated chamber having an entrance and an exit for passage of said articles through said chamber; means for introducing a fluid cryogen that is heavier than air including flowable vaporizable solid particles and gaseous fluid into contact with said articles at an intermediate section of said chamber between said entrance and exit during said passage, said means for introducing said fluid cryogen being variable to provide a variable fluid input rate; control means comprising a temperature sensor at said chamber exit and damper means operated thereby for controlling the amount of fluid cryogen directed toward said exit; a container means at said exit for receiving cryogen gas from said chamber exit; and means for moving said gas to a place of disposal spaced from said chamber, thereby limiting flow of said fluid cryogen to the ambient adjacent to said apparatus to a maximum of about 5,000 parts of cryogen gas per million parts of ambient atmosphere, by weight.

4. Apparatus for refrigerating articles, comprising: means defining a thermally isolated chamber having an entrance and an exit for passage of said articles through said chamber; conveyor means in said chamber for causing said passage of said articles; means for introducing a fluid cryogen including flowable vaporizable solid particles and gaseous fluid into contact with said articles at an intermediate section of said chamber between said entrance and exit during said passage; vaporizing means for aiding in vaporizing any of said solid particles remaining on said articles before said articles reach said exit, thereby aiding the extraction of additional heat from said articles; recirculation means for directing said vapor in a recirculation loop from said intermediate section toward said chamber entrance in refrigerating relationship with said articles and back to said intermediate section for mixing with said fluid cryogen from said means for introducing; and means for withdrawing a selected amount of said gas from said recirculation loop and from said chamber.

5. The apparatus of claim 4 wherein said recirculation means comprises a baffle extending from said intermediate section toward but short of said chamber entrance and said chamber is provided with a return passage adjacent said means for introducing leading from the chamber to the means for introducing for mixing recirculated fluid with freshly introduced fluid.

6. The apparatus of claim 4 wherein said means for vaporizing said solid particles on said articles comprises a sublimation zone of said chamber adjacent said chamber exit through which said articles with the solid particles thereon are directed, and there are provided in said section agitating means for said gas for directing gas transversely to and against said articles.

7. The apparatus of claim 6 wherein said agitating means comprises a plurality of longitudinally spaced blower means for directing successively spaced circulating streams of said gaseous fluid transversely to said passage of articles.

8. The apparatus of claim 4 wherein said recirculation means comprises a baffle extending from said intermediate section toward but short of said entrance.

9. The apparatus of claim 8 wherein said baffle is located beneath said conveyor means but above the bottom of said chamber to provide a return passage of said loop between said bottom and said baffle.

10. The apparatus of claim 8 wherein the opposite end of said baffle is positioned adjacent said means for introducing on the side thereof that is adjacent said chamber exit.