US2770111A - Vacuum produce cooler - Google Patents

Description

Nov. 13, 1956 J. c. REAR VACUUM PRODUCE COOLER 4 Sheets-Sheet 1 Filed Oct. 10 1955 mm Fm wmw mm mm I N V EN TOR. JAMES c. REAR BY 2* MM A T TORNEYS Nov. 13, 1956 J. c. REAR VACUUM PRODUCE COOLER 4 Sheets-Sheet 2 Filed Oct. 10 1955 Q m HI HW W INVEN TOR. JAMES C. REA/P KM/[Mex A T TORNEYS NOV. 13, 1956 Q REAR VACUUM PRODUCE COOLER 4 Sheets-Sheet 3 INVENTOR. JAMES C. REAR Filed Oct. 10, 1955 A TTO/PNEYS NOV. 13, c REAR VACUUM PRODUCE COOLER Filed Oct. 10-, 1955 4 Sheets-Sheet 4 VVV HVVV

A TTURNEVS VACUUM PRODUCE COOLER James C. Rear, Berkeley, Calif., assignor to The Union Ice Company, a corporation Application October 10, 1955, Serial No. 539,309

3 Claims. (Cl. 62-169) My invention relates particularly to devices for cooling produce such as lettuce, corn, cauliflower and the like by a reduction in the ambient pressure so that moisture near, on or in the produce in evaporating extracts heat from the produce. While various different means for effectuating this operation have appeared in the patent literature and in practice, the present development is especially concerned with the utilization of water ice as a part of the pressure reduction mechanism. When moisture is removed in the form of steam from articles being refrigerated, it is economically necessary to condense the steam into liquid form and withhold it from the vacuum pumps in order not to overload the vacuum pumps. Otherwise, if the pumps must handle the condensible as well as the non-condensible fluids they must be so large that the process is not commercially feasible. Brine coils or refrigerator coils of some sort are utilized as condensers I for such purposes and water ice has been proposed. Difficulties have arisen in practical application, however, since it is difficult to utilize the ice properly.

It is therefore an object of my invention to provide a vacuum produce cooler operating with an ice condenser and which is satisfactory commercially.

Another object of my invention is to provide a vacuum produce cooler that can be utilized with the usual produce handling mechanism.

Another object of my invention is to provide a vacuum produce cooler which can readily be serviced with an appropriate supply of ice.

Another object of my invention is to provide a vacuum cooler in which the ice is utilized so that the resulting operation of the structure is uniform and is satisfactory.

Another object of my invention is, in general, to provide an improved, practical vacuum produce cooler.

Other objects, together with the foregoing, are attained in the embodiments of the invention described in the accompanying description and illustrated in the accompanying drawings, in which Figure 1 is a plan of a vacuum produce cooler constructed in accordance with my invention.

Figure 2 is a cross section, the plane of which is indicated by the line 22 of Figure 1 but drawn to an enlarged scale and with parts of the structure broken away to reduce the size of the figure.

Figure 3 is a cross section, the plane of which is indicated by the line 33 of Figure 1.

Figure 4 is a cross section, the plane of which is indicated by the line 44 of Figure 1.

Fi ure 5 is a cross section, the plane of which is indicated by the line 5-5 of Figure 3.

Figure 6 is an isometric view of a fragment of the ice grid and adjacent structure.

Figure 7 is a diagrammatic cross section of a modified form of vacuum produce cooler.

The vacuum produce cooler of the invention can be incorporated in a number of different forms and, for one variation, reference is made to the co-pending related application of Frank J. Hibbs, In, filed October 10, 1955, with Serial Number 539,334, Some of the subject matter Patented Nov. 13, 1956 disclosed in this application and not claimed herein is claimed in the mentioned Hibbs application.

In the customary installation, there is provided on a suitable ground area or platform a produce tube 6 which preferably is made of a circular cylindrical, metallic member closed at one end 7 and having a door 8 at the other end. The produce tube 6 is conveniently mounted on structural members 9 so that it is substantially hori zontal and so that a pair of tracks 11 and 12 disposed within the tube along the bottom thereof are approximately level with the surrounding ground area. This is for the purpose of receiving a dolly 13 including a frame 14 about as long as the tube 6 and on which support Wheels 16 are mounted. Additionally, the dolly 13 carries side wheels 17 adapted to run lightly on angle guides 19 fixed within the produce tube 6 near the bottom thereof.

With this arrangement, the dolly 13 having thereon appropriate lading 21, such as lettuce packages, can be wheeled into the produce tube 6 when the door 8 is open, the weight of the loaded dolly being supported on the tracks 11 and 12 while the assembly is guided by the side wheels 17. Additionally, side plates 22 and 23 extend throughout most of the length of the produce tube, being supported on uprights 24, so that in the event the lading 21 is incxactly piled or is not arranged as evenly as illustrated, the packages cannot fall from the dolly. The plates 22 and 23 are so located that there is a substantially even or uniform space surrounding most of the lading. The lading either contains suificient natural moisture or has been sufiiciently moistened so that when some or all of such moisture evaporates at a sub-atmospheric pres sure, the evaporating moisture will withdraw sufficient heat from the produce to reduce its temperature from the undesired high value when the produce is entered into the tube to the desired low value when the produce is withdrawn therefrom. Cooling time, in practice, is about twenty minutes.

Since it is desired to remove substantially all of the atmosphere from the produce tube 6; that is, to establish a satisfactory vacuum therein, the tube adjacent its upper portion has a connection 26 to a valve housing 27 into which an outlet duct 28 extends. There is a suitable seat 29 on the end of the duct 28 and opposite the seat within the casing 27 there is provided a valve 3'1. This is conveniently operated by servo-mechanism 32 from an open position, as shown in Figure 2, into a closed position with the valve 31 abutting the seat 2 9. Also joined to the valve body 27 between the seat 29 and the connector 26 is a vacuum line 33. This extends through a control valve 34 into a pipe 36 leading to a vacuum pump 37. Various different sort-s of vacuum pumps can be utilized but preferably the vacuum pump "37 is a mechanical, positive displacement pump appropriately driven by an electric motor 38. When the valve 31 is closed and the motor 38 is energized, the pump '37 is effective to withdraw fluid from within the produce tube 6 and to discharge the withdrawn material through an outlet 39 to the atmosphere. The rate at which the pump 36 can reduce the pressure within the produce tube 6 with the mechanism so far described is relatively slow, too slow for practicality. For that reason, there is provided additional mechanism to speed up the operation. The conduit 28 extends to a refrigeration tube 41. This tube is likewise a circular cylindrical, metal vessel suitably supported on feet 42 and closed at its opposite ends by pressure resisting heads 43 and 4 4. The conduit 28 is connected into the refrigerator tube 41 "by a pair of d ucts 46 and 47 symmetrically arranged on opposite sides of the vertical center line of thetube and opening into the'upper part of the refrigerator tu-b'e lDisposed within the refrigerator tube 41 adjacent the bottom portion thereof is an 'ice grid 51. This is preferably a somewhat open supporting platform conveniently fabricated of a number of structural shapes, such as angle irons, disposed with their V portions uppermost and extending lengthwise of the tube 41 substantially from one end thereof to the other. At appropriate intervals, the grid angles 51 are supported on cross beams 52 so that a sturdy, foramin'ous grid is provided.

Since it is desired to utilize water ice as a refrigerating medium, the refrigerator tube 41 along its uppermost portion and at appropriate intervals is provided with a number of icing hatches 3. Each of these is a relatively large opening into the interior of the tube 41 and is normally closed by a pressure cap 54. The cap or cover is disposed on hinges or is otherwise mounted so that the cap can readily be swung completely out of the way when access is to be had to the interior of the tube 41 through the hatch opening '53. A fastening '56 is provided to hold the cap in pisition when it is closed.

Conveniently supported on the tube 41 by suitable brackets 58 is an icing platform 59 substantially co-planar with the open hatches 53 and disposed at a proper height for icing by truck or conveyor. When the hatch covers or caps 54 are open, broken ice on the platform 55? in suitably sized pieces is dumped through the hatch openings onto the ice grid 51 so that it fills substantially the entire length of the refrigerating tube 41 from the grid to a relatively high point therein. The covers 54 are closed when sufficient ice has been loaded into the tube 41. On the interior of the tube 41 there is provided an inserted corrugated Wall section 6 1 on each side so that the tube 41 is protected from the falling ice and so that some additional strength is imparted to the tube.

As a result of the filling operation, ice in irregular shaped sizes and chunks is deposited on the grid. I therefore aiford means for utilizing substantially all of the exposed ice surface available as heat transfer surface and for doing so in a uniform fashion despite the heterogeneous character of the ice lumps. It is especially desirable to avoid any short circuiting or any large free path through the ice of such a nature that the remainder of the more firmly packed ice is not utilized. For that reason, I provide on the interior of the tube 41 over the intersection of the connections 46 and 47 with the tube a pair of manifold plates 62 and 62 extending for nearly the full length of the refrigerator tube 41 and fastened tightly to the walls of the tube to provide ducts. At appropriate intervals, the manifold plates 62 and 62 are pierced by openings 63. Thus, fluid flowing into the tube 41 through the "connections 46 and 47 is necessarily distributed quite evenly along the length of the tube.

Additionally, I provide means for withdrawing gases from the tube 41 in a uniform fashiom For that reason, there is preferably disposed beneath each of the angles '51 of the ice grid a tube 63 having a number of perforations 64 in its length and constituting one of a number of similar tubes together making up a suction manifold generally designated 66. The tubes 63" are connected in pairs to collector pipes 67 and 67 in turn joined together outside of the tube 41 in a conduit 68. This leads through a control valve 69 to a junction with the vacuum pipe 36. With this manifold arrangement underneath the ice grid, gases within the tube 41 are uniformly and evenly withdrawn from all portions of the tube and are eventually delivered to the vacuum pump 37 for discharge to the atmosphere.

The operation of the structure melts some of the ice on the grid and the resulting water flows through a pipe 71 in the very bottom of the tube 41 into a tank 72 disposed in a location for the most part below the pipe 7 1. The tank 72 at its upper portion is connected by a pipe 73 having a valve-74 therein to the 'upper portion of the tank 41 within the manifold 62. Additionally,

the tank 72 is provided with a drain pipe 76 having a 4 valve 77 therein and leading to the atmosphere or any equivalent drain.

In the use of this structure, the valve 31 is closed, the produce tube 6 is connected to the atmosphere and the door 8 is opened. La-ding to be cooled is wheeled in on the dolly 13 and the door 8 is hermetically closed. The valve 34 is opened and the vacuum pump 37 reduces the pressure within the produce tube 6 to a reasonable value whereupon the valve 31 is opened. Simultaneously the-valve 34 is closed and the valve 69 is opened. The vacuum pump 37 then draws-the atmosphere; that is air, steam or water vapor, and condensible and non-condensible gases from the produce tube 6 through the conduit 28 and through the'distriouting manifolds 62 and 62 into the refrigerator tube 41. The evenly distributed flow continues down over the ice on the grid 51 and much of vapor within the pumped atmosphere is condensed onto the ice, thereby reducing the volume of the gases substantially. Condensation of the vapors results in the melting of some of the ice and the resulting water flows through the pipe 71 into the sump tank 72 which at that time is connected to the interior of the tube 41 not only through the pipe 71 but also through the pipe 73 since the valve 74- is open. The valve 77 at this time is closed.

The remaining non-condensiblc gas, after having travelled over the ice and through the grid 51, enters the perforations 64 in the tubes 63' and flows through the pipes 67 and 68, through the valve 69 and the pipe 36 into the vacuum pump 37 and from thence into the atmosphere through the discharge pipe 39. The pumping continues until such time as the evaporating moisture or steam from the packages of produce on the dolly 13 has withdrawn sufficient heat from the produce to reduce its temperature to the selected value. At that time, the valve 31 is closed and the interior of the tube 6 is subjected to atmospheric pressure by an appropriate valving mechanism. The door 8 is opened and the dolly 13 and its contained produce are withdrawn in cool condition. Another produce 'dolly is introduced and the cycle is repeated.

Periodically, the ice supply on the grid 51 is sufficiently depleted so that the refrigerator tube 41 is brought up to atmospheric pressure for servicing. Preferably, the tube 41 is brought up to normal air pressure at the same time the tube 6 is at atmospheric air pressure. When the pressure is atmospheric inside the tube 41, the catches 56 are released and the ice hatches 54 are readily opened. Ice on the platform 59 is already in or is broken up into suitable size chunks and is introduced as previously described. The hatches 54 are then closed and vacuum operation is resumed. During the ice loading time, the valve 77 is preferably open so that the accumulated water in the sump tank 72 is permitted to discharge to waste. Following this, the valve 77 is closed so that the vacuum cycle can be repeated.

It has been observed in practice with this structure that the produce is cooled with unusual effectiveness. Apparently the large condensing surface of the ice chunks in the refrigerator tube 41 is effective to assist the vacuum pump very quickly to lower the pressure on the produce. If the produce is like lettuce or cauliflower some physical expansion of such produce takes place. This gives a freer path to release the interior moisture and permits free breathing of gases from the inside of the produce. There is a much more marked effect with the large ice surface than is obtained by any normal or practical installation of refrigerating coils utilizing brine or ammonia or the like. The resulting, cooled produce is, therefore, somewhat superior in appearance and since it is initially somewhat expanded, it cools to the desired temperature in a somewhat shorter cycle.-

If desired, the valve 31 and its appurtenances can be omitted but then each time the tube 6 is brought from a vacuum condition'up to atmospheric pressure the tube 41 is likewise brought up to atmospheric pressure. It is then necessary for the vacuum pump subsequently to reduce both tubes to a low pressure. When the valve 31 is utilized, the vacuum can be held in the tube 41 even though the tube 6 is brought up to air.

Under some circumstances, it is desirable to supply a refrigerating medium to the refrigerating tube 41 without interrupting the vacuum cycle thereof. Then the structure is augmented as shown in Figure 7. There is provided an ice supply conveyor 81 discharging ice chunks 82 through a valve opening 83 into a container 84 disposed above the refrigerator tube 41. The container 84 is intermittently closed by a valve 86 appropriately controlled by an operating device 87. The chamber 84 at its lower end has a discharge opening 88 controlled by a valve 89 connected by mechanism 91 to a suitable operating device (not shown). Leading from the opening 88 is a conduit 92 forming part of a conveyor housing 93 which extends along the top of the tube 41. A series of openings 94 establish communication between the housing 93 and the interior of the tube 41. A screw conveyor 96 is disposed within the housing 93. The shaft 97 of the conveyor extends through appropriate packing 98 to a connection with an electric drive motor 99.

In the operation of this structure, ice chunks 82 are discharged into the hopper 84 when the valve 86 is open and the valve 89 is closed. At an appropriate time, the conveyor 81 is stopped, the valve 86 is closed and the valve 89 is opened. By this means the chamber 84 forms a sort of air lock so that when the valve 89 is opened, the interior of the chamber 84 assumes a sub-atmospheric pressure substantially the same as that in the tube 41. Then when the valve 89 is opened, the ice feeds by gravity from the chamber 84 into the hopper 92. After a suitable charge has been received in the hopper, the valve 89 is closed, the valve 86 is opened to the atmosphere and the chamber 84 can again be charged. The ice at sub-atmospheric pressure within the hopper 92 falls by gravity into the conveyor chamber 93 and is distributed evenly along the length of the tube 41 by the screw 96, appropriate portions of the ice charge falling through the openings 94 at spaced intervals throughout the length of the tube 41. By this means, the refrigerating tube is supplied intermittently with additional refrigerant, such as water ice, but it is not necessary to bring the entire tube 41 up to atmosphere in order to renew the ice supply.

What is claimed is:

l. A vacuum produce cooler for use with a produce tube comprising a refrigerator tube, an ice supporting grid in said refrigerator tube, hatches in said refrigerator tube for ingress of ice to said grid, a drain tank, means for connecting said drain tank to said refrigerating tube beneath said grid and to the atmosphere, valves in said connecting means, a vacuum pump, a perforated suction manifold in said refrigerating tube beneath said grid, means for joining said suction manifold to said pump, inlet manifolds in said refrigerating tube above said grid, and means for connecting said inlet manifolds to said produce tube.

2. A vacuum produce cooler for use with a produce tube comprising a refrigerator tube, an ice-supporting grid in the lower portion of and spaced from the bottom of said tube, said grid having members extending lengthwise of said tube, hatches in said refrigerator tube for ingress of ice of said grid, a drain connected to said refrigerator tube below said grid, a valve in said drain, a vacuum pump, a perforated suction manifold in said refrigerator tube below said grid, said suction manifold having pipes extending lengthwise of said tube below said grid members, means for joining said suction manifold to said pump, inlet manifolds in the upper portion of said tube above said grid and extending lengthwise of said tube, said inlet manifolds having openings at intervals therein, and means for connecting said inlet manifolds to said produce tube.

3. A vacuum produce cooler for use with a produce tube comprising a refrigerator tube, an ice-supporting grid in the lower portion of said refrigerator tube, hatches in the top of said refrigerator tube over said grid, an ice platform mounted on said refrigerator tube substantially flush with said hatches, a vacuum pump, a suction manifold in said refrigerator tube beneath said grid, means for joining said suction manifold to said pump, inlet manifolds in the upper portion of said refrigerator tube including plates joined to the wall of said tube and having openings therein at intervals, and means for connecting said inlet manifolds to said produce tube.

References Cited in the file of this patent UNITED STATES PATENTS

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