US1958890A

US1958890A - Cooling apparatus

Info

Publication number: US1958890A
Application number: US439278A
Authority: US
Inventors: Benjamin S Foss; Samuel M Anderson
Original assignee: BF Sturtevant Co
Current assignee: BF Sturtevant Co
Priority date: 1930-03-27
Filing date: 1930-03-27
Publication date: 1934-05-15
Anticipated expiration: 1951-05-15

Description

May 15, 1934. 955 r AL 1,958,890

COOLI NG APPARATUS Filed March 27, 1930 7 Sheets-Sheet l INVENTOR5 B- 5- Foas and 6.1V Adm 600 BY ATTORNEY y 1934- B. s. Foss El AL 58,%

COOLING APPARATUS Filegi March 27, 1930 7 Sheets-Sheet 2 C ULl/YG ran m B Y OM, OM m ATTO FE N EY May 15 1934.

B. s. FOSS ET AL 1,958,890

COOLING APPARATUS Filed March 27, 1930 7 Sheets-Sheet 3 INVENTORS ""B- S- Foss $.01. Alva-Eas DM DW ATTORNEY,

May 15, 1934. B. s. FOSS ET AL 1,958,890

COOLING APPARATUS Filed March 27, 1930 7 Sheets-Sheet 4 :rum h.

INVENTORS 5. 6- F055 and BY 5 M- ANQEQsOM o m ATTORNEY y 1934. B. s. FOSS El AL 1,958,890

COOLING APPARATUS Filed March '27, 1930 7 Sheets-Sheet 5 INVENTORS B- 6. F05: and BY 5 M. flvaaesou ATTORNEY May 15, 1934.

B. SQFOS'S El AL COOLING APPARATUS Filed March 27, 1930 7 Sheets-sheaf. 6

Ma 15, 1934. B, 5, F055 5M 1,958,890

COOLING APPARATUS Filed March 27, 1950 7 Sheets-Sheet 7' 24 awuentow 8- 3- F055 nd 5- M. fluosesolv $31 M flblio'vnw Dunn Dwvm +amalnm Patented May 15, 1934 UNITED STATES COOLING APPARATUS Benjamin S. Foss, Brookline, and Samuel M. Anderson, Sharon, Mass., assignors to B. F.

Sturtevant Company,

Application March 27,

17 Claims.

This invention relates to apparatus for chilling or freezing foods.

An object of the invention is to chill or freeze foods without drying the foods.

Another object of the invention is to chill or freeze foods by passing a current of cold air at high velocity over the foods.

Another object of the invention is to provide economical and eflicient apparatus for chilling or freezing foods.

Other objects of the invention will be brought out in the following description of the invention. -According to a feature of the invention, the food to be frozen is placed in an air-tight passage and a current of air, cooled to a temperature so low that the vapor pressure of water corresponding thereto is substantially zero, is passed at high velocity over it. At temperatures above -40 Fahrenheit, the vapor pressure of moisture is effective to add an appreciable amount of aqueous vapor to the surrounding space. It is proposed in this invention to freeze foods by passing air thereover at temperatures so low that at all times during the freezing process the vapor pressure is negligible. By using such low temperatures, the food is quickly frozen without any drying action.

This invention comprises apparatus including a plurality of trays for supporting the food to be chilled or frozen, conveyors for feeding the trays into and out of the chilling or freezing chamber, insulated chambers with air-tight doors between the atmosphere and the entrance and exit parts of the freezing chamber, for preventing the heating and escape of the cooling air, a fan unit for producing a high velocity current of air, a spray chamber for cooling the air before it enters the freezing chamber, refrigeration apparatus for supplying the cooling spray to the spray chamber,

a slow-moving. conveyor within the freezing chamber for taking the plurality of the food trays as a unit through the cooling air at a slow rate of speed, and the necessary additional equipment for operating the apparatus. The invention will now be described in mor detail with reference to the drawings, of which:-

Fig. 1 is a chart showing vapor density curves for water vapor; I

Fig. 2 is a side view of a partially assembled freezing unit according to this invention. A portion of the spray chamber is broken away to show the arrangement of the spray nozzles.

Fig. 3-is a. side view of a portion of the apparatus shown by Fig. 2. One of the side walls of the freezing chamber is removed for the purpose Boston,.Mass.

1930,,sbm1 No. 439,278

of showing the arrangement of the conveyor therein.

Fig. 4 is a view looking down upon the apparatus shown by Fig. 2;

Fig. 5 is a schematic view of the refrigeration apparatus which supplies the cooling spray to the spray chamber;

Fig. 6 is an enlargedview of a portion of the conveyor within the freezing chamber and of the insulating chamber at the entrance end of the freezing chamber;

Fig. '7 is a sectional view along the lines 7-? of Fig. 6 and shows a view of the conveyor within the insulating chamber;

Fig. 8 is a sectional view along the lines 8-8 of Fig. 6 and shows the arrangement of the airtight insulating doors;

Fig. .9 is a view of the tray on which the food to be frozen is supported and which is adapted to be carried through the freezing chamber by the conveyor therein;

Fig. 10 is a side view of two of the conveyor arms of the conveyor within the freezing chamber. One of the trays, such as shown by Fig. 9, is mounted on the upper conveyor arm, an end view being shown. 0n the lower arm only the lower portion of a tray is shown.

Fig. 11 shows a portion of a tray and is for the purpose of illustrating how the upper and lower portions of the tray are held together.

Fig. 12 is a side view of the exit insulating chamber and shows the exit conveyor and the mechanism for operating the heat insulating doors;

Fig. 13 is a partial side view of the apparatus shown by Fig. 12;

Fig. 14 is a view of a portion of the freezing chamber showing a portion of the mechanism for driving the conveyor therein and a portion of the discharge apparatus forremoving the tray containing the frozen food from the freezing chamber;

Fig. 15 is a sectional view along the lines15-15 of Fig. 14 showing a portion of the conveyor for conveying the food-containing tray from the freezing chamber;

Fig. 16 is a sectional view along the lines 16+ 16 of Fig. 14 showing the end of a tray resting on a roller of the conveyor for carrying the tray with frozen food from the freezing chamber;

Fig. 1'7 is a partial view in section of a freezing chamber having horizontally arranged intake and exit chambers. 1

Referring now to Fig'. 1, a chart showing a vapor density curve for water vapor is plotted. It

may be seen that the vapor density is substantially zero at temperatures below minus 40 F. It is at temperatures below minus 40 F. that it is preferred to have the current of air which is used to freeze the food according to this invention.

Referring now to Figs. .1 and 2 and 4 of the drawings, the fan unit 20, which is driven by the motor 21, produces a high velocity current of air which travels through the enclosed passageway 22 into the spray chamber 23 and out of the spray chamber into the freezing chamber 24, where it passes thru the conveyor 25 (Fig. 3) and is returned through the passageway 26 to the fan unit 20, where it is circulated again. The spray chamber 23 has contained therein, at the side where the air from the fan unit 20 enters, the fine mesh filter 2'7 which is preferably made up of galvanized steel wool. This filter 27 serves to catch any moisture which may be contained in the air which passes through it. The fine mesh filter 28'closes off the side of the spray chamber 23 through which the air passes on its way to the freezing chamber 24. This filter is made up similar to the filter 27 and serves to catch any entrained particles of water from the current of air passing from the spray chamber 23. The spray chamber 23 contains the spray nozzles 29 which project into the spray chamber, in a direction opposing the air current passing therethrough, a brine solution, such as calcium chloride, having a temperature of approximately minus 70 F. which serves to cool theair passing through the spray chamber to a temperature of approximately minus 65 F. The brine solution issupplied to the spray chamber through the supply pipe 30,-through which the brine is supplied from the cooling tank 31 shown by Fig. 5. The spray, after passing through the spray chamber 23, deposits on the drain pan 32 thereof and is returned to the refrigeration apparatus shown by 5 through the drain pipe 33.

Referring now, to Fig. 5, the operation of the refrigeration apparatus will be explained. The brine solution from the drain pan 32 of the spray chamber shown by Fig. 2 is forced by means of the pump 34 through the cooling tank 31 out to the brine supply pipe 30 to the spray nozzles 29 of the spray chamber 23 shown by Fig. 2. The compressor 35, driven by the motor 36, forces the refrigerant, which may be methyl chloride, or other suitable refrigerant, through the condenser 37, the receiver 38, supply pipe 39, expansion valve 40, into the cooling tank 31, from which it circulates out through the pipe 41 again into the compressor 35. The pump 42 forces cooling water through the condenser 37, this cooling water passing out of the condenser 3'7 through the pipe 43 into the cooling tower 44 and through the pipe 45 into the pump 42 again.

Referring now to Fig. 3, the freezing chamber 24 has contained therein the slow-moving conveyor 25 which is adapted to carry the food to be frozen at a slow rate ofspeed through the freezing chamber, the arrangement being such that the cold current of air passes in contact .for a long period of time with the food to be the conveyor 25. The conveyor 46 serves to carry the food to be frozen into the entrance insulating chamber 47, from which it passes on to the arms 48 of the conveyor 25. The conveyor 49 serves to carry the frozen food from the freezing chamber 24 after it has been carried through the chamber by the conveyor 25. The motor 50 drives the conveyor 25 by a ratchet arrangement shown in more detail by Fig. 14 and drives also theflentrance conveyor 46 and the exit conveyor Referring now to Figs. 9, 10 and 11, the tray on which the food to be frozen is supported in its passage through the freezing chamber and its arrangement on the arms of the slow-moving 9'3 conveyor of the freezingchamber will be explained. The tray 50 has mounted thereon the four squares of food 51, the food to be frozen being grouped in these four separate squares for convenience of handling. The tray 50 has its 5 base portion built up of a plurality of wires 52 which are hooked into the, end portions 53. The food groups are placed on these base portions and the retaining wires 54 are clamped over the food by means of the clamps 55 which are adapted to slip over the end portions 53 of the base and the looped portions 56 of the retaining wires 54. Fig. 10 shows two conveyor arms 48 which make up the conveyor which carries the food through the freezing chamber. The upper arm has mounted thereon an assembled tray; the-lower arm has mounted thereon only the base portion of the tray. Fig. 6 shows the arrangement whereby the food-laden trays are introduced into the freez ing chamber. The conveyor 46, only a portion of which is shown, abuts against the freezing chamber inlet 57 which contains the rollers 58 on which the food tray 50 is adapted to slide or roll. The inlet 57 is separated from the heat insulating chamber 47 by means of the partition 59, the air-tight door 60 serving to close off an opening in the partition 59 through which the food tray is permitted to enter. As the food tray passes through the inlet 57 its front portion strikes and depresses the cam 61 on the .shaft 61. The shaft 61 (Fig. 7) extends through one of the rollers 58 and carries on one end the switch arm 59' of the switch 59. As the cam 61 is depressed by an incoming food tray it moves downward against the pressure of a spring (not shown) and the resultant rotation of the shaft 61' causes the switch arm 59' to engage the contacts of the switch 59. The switch 59 controls. the electrical energizing circuit of the door operating solenoid 64. (Fig. 6.) 0n the closing of the switch 59 the solenoid becomes energized and pulls up its plunger against the influence of a spring (not shown) to which is attached the lever arm 63 of the door60, the movement of the plunger of the solenoid 64 and the lever arm 63 causing the door 60 to open to permit the entry of the food laden tray through the opening 65. The door 60 is connected through the spring member 67 to a similar air tight door 68 in such a manner that when the door 60 is closed, the door 68 is open and vice versa. The door 68 closes off the opening 69 which permits the foodladen tray to pass from the insulating chamber 47 into the freezing chamber 24. The food laden tray, when the door 60 is open, passes through the opening 65 onto the rollers 70 and when the door 68 opens passes over the roller 71 onto one of the arms 48 of the slow-moving conveyor 25 in the freezing chamber 24. After the food laden tray passes over the cam 61, the cam is returned to its normal position in which it projects into the-path of an incoming food tray by the influence of its return spring (not shown). return of the cam 61, of course, opens the switch 59 and the solenoid 64 becomes demagnetized.

'The spring (not shown) associated with the plunger of the solenoid 64 forces, through the return movement of the solenoid plunger and the lever 63, the door 60 to close and through the interconnecting member 67 the door 68 to open so that the food laden tray may pass from the insulating chamber 47 into the freezing chamthe toothed wheel 110 which is driven with the conveyor gear 85, has a tooth for each arm 48 of the conveyor 25 and has engaged therewith the pawl 111 of the rod 112, the action being that the rod 112 is lifted against the pressure of the spring 113 as the pawl 111 rides over a tooth of the wheel 110. The rod 112 and the teeth of the wheel 110 are so arranged with respect to the arm 48 of the conveyor 25 that the pawl 111 of the rod 112 is at rest between the teeth of the wheel 110 at the same instant that a conveyor arm 48 of the conveyor 25 is in position to receive a tray from the insulating chamber 47. The upper end of the rod 112 has attached thereto one end of the lever 114 which is pivoted at 115. The other end of the lever 114 has an angle portion 116 which is adapted to press against the link portion 117 of the door 68 when the pawl 111 of the rod 112 is lifted by the movement of the wheel 110 so as to prevent the opening of the door 68. With the pawl 111 seated between the teeth of the wheel 110 the angle portion 116 is removed from the link portion 117, the door 68 then being permitted to open when the energizing circuit of the solenoid is interrupted.

With the door operating arrangement described above, since both of the

doors

60 and 68 cannot be opened at the same time, the cooling air within the freezing chamber is not permitted to escape at the entrance point of the food laden trays. Also the doors are operated only when there are food laden trays at the entrance point to .the insulating chamber 47 so that the doors only open when it is necessary that they do so to permit the passage of food laden trays.

The rollers 70 may be driven by the pulleys 118, a belt being passed over the pulleys 118, these pulleys being driven from the pulley 118' which in turn may be driven from the same power supply that moves the conveyor 25., The rollers 71 may be rotated by the pulleys 71 which inturn may also be driven from the pulley 118. The rollers 70 and 71- may be rotated in a direction to aid the movement of the food laden trays into the freezing chamber 24 or may be rotated in the oposite direction to check the speed of move- This a Referring now to Figs. 3 and 4, it will be explained how the slow moving conveyor within the freezing chamber is actuated. The motor 50 (Fig. 3) drives the gear 72 by means of aworm gear (not shown), the shaft of the gear 72 driving the worm gear 73 which meshes with the gear 74 (Fig. 2) which is mounted on the same shaft or the cam 81 and the pulleys and 76. Referring now particularly to Fig. 14, the cam 81, as it is rotated, moves the lever arm 82which, in turn, carries the ratchet pawl 83 which, in turn, meshes with the gear 84, which is. attached to the conveyor gear 85. The cam 81, as it is rotated through the agency of the motor 50 by the action of the ratchet'pawl 83 of the toothed gear 84, is seen to advance in a series of jumps the slowmoving conveyor within the freezing chamber. Referring now particularly to Fig. 3, the pulleys 75 (only one of which is seen) are rotated with the cam driving gear 74 and these pulleys serve .to rotate the inlet and outlet conveyors, the pulley '75 serving to rotate through the belt the pulley 78 on the inlet conveyer 46, and the other pulley 75 (not shown) serving to rotate, through the medium of the belt 79, in a reverse direction, the pulley 77 of the exit conveyor 49.

Referring now to Figs. 12, 13, 14, 15 and 16, the operation of the device in discharging the foodladen trays from the freezing chamber will be explained. The heat insulating chamber mounted at the exit point of the freezing chamber 24 has attached thereto the two sets of air-

tight doors

91 and 92, the air-tight doors 91 serving to close the opening between the freezing chamber 24 and the insulating chamber 90, and the airtight doors 92 serving to close off the heat insulating chamber 90 from the atmosphere. The doors 91 are normally open and the doors 92 are normally closed. As an arm 48 of the conveyor within the freezing chamber, with a tray of frozen food thereon, moves inline with the rollers 93, the outer ends of the -tray strike the rollers 93, supporting them so that-the arm 48 of the conveyor may move free from the food-laden tray. Fig. 16 shows how this is done. There, one of the ends 94 of a food-laden tray is shown resting on one of the rollers 93. The food-ladentray, once clear from the conveyor arm 48, passes along the rollers 93 through the opening 95 into the insulating chamber 90. Once in the insulating chamber 90, the tray then travels on the rollers 96 until its front end strikes the cam 97 whichis depressed against the resistanceof a spring (not shown) to close the :electrical circuit of the solenoid 99 by means of an electrical switch (not shown) similar to the switch 59 shown by Fig. 7. The solenoid 99' when energized, by withdrawal of its plunger against the resistance of the spring 92' and the upward movement of the lever arm 99 attached to the plunger of the solenoid 99 at one end and to the door 92 at the other end moves the door 92 upward and away from the opening 100 thus allowing the food laden tray to pass from the insulating chamber onto the rollers 101 and ciated electrical switch solenoid 99', the solenoid 99 then becoming de-energized so that the plunger spring 92' forces the door 92 to return to its normally closed position. The door 91 is openedby the closing of the door 92 so that the next food tray from the freezing chamber can enter the insulating chamber 90.

While for the purpose of illustration we have described the insulating air tight doors in the inlet and exit insulating chambers as controlled through the energization of electrical solenoids by the weight of thefood operating levers in the food path, it should be understood that this is not the only way we contemplate operating the insulating doors. In one embodiment we contemplatehaving the inlet and outlet doors geared directly to the conveyor driving mechanism and operated according to the position of the conveyor arms in the slow moving conveyor.

Also while in the description of the apparatus shown by Fig. 6 for preventing the opening of the air tight door 68 and the entrance of the food laden tray into the freezing chamber until an arm of the slow moving conveyor within the freezing chamber is in the proper position to receive it, a mechanical arrangement comprising the toothed wheel 100, the pawl 111, and the rod 112 fonpreventing the opening of the door 68 has been shown, it is not essential that this exact arrangement be used. Electrical contact mechanism may be operated by the movement of the slow moving conveyor within the freezing chamber to control the energization of the solenoid operating the air tight doors.

Therollers 93 and 96 are driven from the pulley 12' by means of the belts 123 and 125 which pass over the roller pulleys 122. The pulley 121 is driven from the pulley120 which in turn is driven by the motor 50 (Fig. 3) It is believed that under most operating conditions it will be necessary to rotate the conveyor rollers by power to prevent their freezing up.

As shown by Figs. 6 and 14 the conveyor guides A are provided to prevent the links of the slow moving conveyor chain from sagging and to keep the conveyor arms 48 in a horizontal position as they move progressively downward through the freezing chamber.

Fig. 17 shows enough of the entrance insulating chamber 47, the freezing chamber 24, the exit insulating chamber 90 and the equipment used in these chambers to illustrate that the food laden trays can be fed horizontally into the freezing chamber and extracted horizontally from the freezing chamber, it not being at all essential that the food laden trays be fed into and taken out of the freezing chamber along inclined paths as shown in other figures. The reference characters used with Fig. 17 are the same as those employed with the figures 6, 7, 12, 13, 14, 15 and 16 and the functioning of the door operating and conveyor mechanism is the same as that previously described so that the operation of the apparatus shown by Fig. 17 will not be described in detail.

The constants of the apparatus herein described are so chosen that the air through the spray chamber 23 has a velocity of from 300 to 500 feet per minute. On passing through the respective channels of the freezing 'chamber 24, the velocity of this air is increased to from 1500 to 2000 feet per minute. It is preferred that the current of air leaving the spray chamber have a temperature of approximately minus 65 F. After passing around the trays of food on a slow-moving conveyor within the freezing chamber, the air is heated up to approximately minus 60 F. and then, on being circulated again through the spray chamber by means of the fan unit, it is cooled again to approximately minus 65 F. It will be noticed that due to the fact that the food-supporting trays 50 are built up of wires withlarge spaces there between, the high velocity current of cooling air passes above and along the upper surface and below and along the under surface of the food to be frozen. In this way substantially the entire surface of the food is exposedequally With the arrangement herein disclosed, a large quantity of food can be efliciently frozen with a minimum of labor and expense. The action of the apparatus is entirely automatic and is believed to be fool-proof. The trays of food are placed on the inlet conveyor 46 and are, taken off of the exit conveyors 49, no human aid being required'during the freezing process. The walls of the freezing chamber, of the air passages and of the insulating chambers may be insulated, as desired, to prevent the heating of the cooling air employed for freezing the food, and with the provision of the airtight doors for preventing the escape and heating of the cooling air through the entrance and exit portions of the freezing chamber, but a minimum required.

The apparatus herein disclosed utilizes compact and efiicient units which may be combined to provide a system of any desired size. The fan units,

amount of energy for cooling the circulating air is v spray chamber units and freezing chamber units with their associated equipment may be grouped together in batteries of units, the batteries of freezing chamber units being fed through a single duct system by as many spray chamber units and fan units as are necessary.

The freezing chamber is seen to contain avertically arranged conveyor fitted with closely spaced horizontal arms, The food trays in passing through the freezing chamber are thus; placed vertically one above the other with very little space between them so'that the most compact arrangement of the freezing apparatus per pound of food is believed to be obtained. With this ar- 'rangement a number of food trays move slowly through the freezing chamber as a unit, the food in all of the trays offering an extended surface for heat transfer from the food to the air.

An advantage of employing a high velocity ourrent of air cooled to a temperature of below minus Furthermore, the inlet temperature of the air is so low that even a slight increase in temperature,

due to contact with the food, still is not sufficier'it to raise the vapor pressure to a point where moisture' in the form of aqueous vapor will be present.

Obviously, with this process there can be no drying action of the food. The food is thoroughly frozen during its movement through the freezing chamber. On some types of food such as fish, for example, a protective layer on the outside of the food may be frozen, this protective layer tending to maintainwithin the food allits original moisture. With this method the food can be frozen throughout, or an outside layer may be frozen, either method being effective to preserve the juices of the food with their original flavors.

Another advantage of cooling air to a temperature such that the vapor pressure of moisture is negligible is that more economical refrigeration is obtained. In an air washer or brine spray cooler, when the temperature is around the ordinary temperatures of 30 to 40 F. above zero, the air to be cooled comes in contact with the cooling spray and is humidified to 100%. By working at a temperature of at least 40 F. below zero this humidifying action cannot take place and consequently a reduced amount of refrigeration is required to obtain a given drop in air temperature over what would be required were the temperatures at a higher level, say around 30 to 40 above zero F.

While it is preferred that the apparatus herein disclosed be operated at temperatures so low that practically no aqueous vapor is present there may be conditions, due to the character of the material being frozen, or otherwise, where it may be desirable or necessary touse air at a higher temperature, at .which a substantial percentage of aqueous vapor will be present. The invention herein disclosed may be used under these conditions as well as under conditions where it is desired that the air be cooled to temperatures below that at which the vapor pressure is negligible. When it is desired to utilize this invention with air at temperatures sufficiently high that aqueous vapor may be present, due to the fact that the cooling air passes through the spray chamber, the air is saturated with aqueous vapor previous to the application of the air to the material to be frozen, thereby preventing any further saturation at the temperature of application. Inasmuch as the air is supplied in sufficient volume and with sufficient velocity so that only a minimum rise in 1 temperature of the air is permitted, the drying effect will be entirely negligible so far as certain classes of foods and materials are concerned. It is seen, therefore, that this invention can be used with equal facility with air, of such low temperatures that the aqueous vapor present is negligible and with air of high temperatures, when an appreciable amount of aqueous vapor may be present.

While under ordinary conditions air will be used as the cooling medium, it is obvious that other gases and gaseous mixtures may be employed. For example, gases like hydrogen having a high specific heat, may be employed. The capacity of hydrogen for absorbing a large amount of heat per unit of weight employed might, under certain circumstances, prove desirable, or a nonoxidizing gas or a germicidal gas, as conditions may warrant could be used.

While the liquid sprayed through the spray chamber has been described as being a brine solution, it should be understood that any solution having the desired cooling effect may be employed. In fact, it may be desirable to employ a glycerine solution, the advantages of such a solution being that it may be cooled to extremely low temperatures and that-it does not have the tendency to cause the rusting of the metalportions of the apparatus.

Whereas one embodiment has been described for the purpose of illustration, it should be underto be limited to the one embodiment illustrated.

While for the purpose of'brevity the word food has been used in the specification and claims it should be understood that the invention is not limited to the freezing or cooling of foods. The invention herein disclosed does not reside. in the cooling or freezing of a particular substance such as food but resides broadly in the cooling methods and apparatus evolved by us, one embodiment of which has been described. We intend, therefore, that the word food in the claims shall in meaning include all elements, organic and inorganic compounds and combinations of elements.

Having described our invention; what we claim as new and desire to secure by Letters Patent is 1. Food cooling apparatus comprising means for producing a current of gas, means for cooling said gas, a cooling chamber through which said and means for preventing the escape of said gas during introduction and withdrawal of said food.

3. Food cooling apparatus comprising means for producing a current of gas, means for 0001 ing said gas and adding aqueous vapor thereto, a cooling chamber through which said gas and vapor is circulated, means for introducing food into said chamber and a slow moving conveyor in said chamber for carrying said food therethrough said food being mounted on said conveyer so that substantially its entire surface is exposed to said gas.

4. A food cooling apparatus comprising a cooling chamber, means for passing a. current of cooling air through said chamber, a conveyor for conveying food to said chamber, an insulating chamber between said conveyor and sa d cooling chamber, a conveyor for carrying food rom said cooling chamber and an insulating chamber between said second conveyor and said cooling chamber.

5. A food cooling apparatus comprising a cooling chamber, means for passing a current of cooling air through said chamber, an insulating chamber at the entrance to said cooling chamber, and means within said insulating chamber for preventing the escape of said cooling air from said cooling chamber when food is being introduced therein.

6. Food cooling apparatus comprising a cooling chamber, means for passing a current of cooling air through said chamber, an insulating chamber at the entrance to said cooling chamber, an airtight door between said insulating chamber and said cooling chamber for the entrance of food into said cooling chamber, another airtight door between said cooling chamber and the outside air for the entrance of food into said insulating chamber and means whereby one of said doors is closed when the other of said doors is open.

7. Food cooling apparatus comprising ,a cooling chamben'means for passing a current of ing chamber, means for passing a current of cooling air through said chamber, an insulating chamber at the exit point of said cooling chamber, an airtight door between said insulating chamber and said cooling chamber for the withdrawal of food from said cooling chamber into said insulating chamber, another airtight door between said insulating chamber "and the outside air for the withdrawal of food from said insulating chamber and means whereby one of said doors is closed when the other of said doors is open.

9. Food cooling apparatus comprising a cooling chamber, an entrance chamber connecting with said cooling chamber, means for feeding food to said entrance chamber, a door into said entrance chamber, a second door between said ontrance chamber and said cooling chamber, and means controlledby the movement of the food to said entrance chamber for closing the door to said cooling chamber and opening the door to said entrance chamber. Y

10. Food cooling apparatus comprising a cooling chamber, an exit chamber connecting with said cooling chamber, means for feeding food from said cooling chamber into said exit chamber, a door separating said cooling chamber and said exit chamber, a second door between said exit'chamber and the outside, and means controlled by a movement of the food through said exit chamber for closing said first mentioned door and opening said second mentioned door.

11. Food cooling apparatus comprising a cooling chamber, an entrance chamber connecting with said cooling chamber, means for feeding food into said entrance chamber, a door into said entrance chamber, a second door between said entrance chamber and said cooling chamber, means for carrying the food through said entrance chamber, and means controlled by the movement of food to said entrance chamber for closing said second mentioned door and opening said first mentioned door.

12. Food cooling apparatus comprising a cooling chamber, an entrance chamber connecting with said cooling chamber, a door into said entrance chamber, a second door between said entrance chamber and said cooling chamber, means for carrying food to said entrance chamber, means for carrying food through said cooling chamber, and means controlled by the movement of the food to said entrance chamber for closing said second mentioned door and opening said first mentioned door, and means controlled by said means for carrying the food through said cooling chamber for closing said first mentioned door and opening said second mentioned door.

13. Food cooling apparatus comprising a cooling chamber, means for introducing food into said therefrom.

cooling. chamber, vmeans for carrying the food through said chamber, an exit chamber, a door separating said cooling chamber and said exit chamber, a second. door separating said exit chamber from the outside, means controlled by the movement of the food through said cooling chamber for closing -'said second mentioned door and opening said first mentioned door, and means controlled by the movement of said food through said exit chamber for opening said second mentioned-door and closing said first mentioned door.

14. Food cooling apparatus comprising a cooling chamber, an entrance chamber connected with said cooling chamber, a first door through which the food is=fed into said entrance chamber, a second door through which the food passes from said entrance chamber to said cooling chamber, control means for opening and closing said doors, means controlled by the movement of the food to said entrance chamber for actuating said control means to close said second door and open said first door, a conveyer in said cooling chamber having a plurality of food carrying sections passing said second door, and means controlled by the movement of said'conveyer for'actuating said control means to open said second door and to close said first door.

15. Food cooling,,apparatus comprising a cooling chamber, a continuously moving food carrying conveyer within said chamber, means for passing a cooling gas through said chamber, means for feeding food to the conveyer within said chamber, and means controlled by the movement of the food and the conveyer for introducing the food into the chamber while preventing food from the chamber while preventing the escape of cooling gas therefrom.

17. Food cooling apparatus comprising a cooling chamber, a continuously moving food carrying conveyer within said chamber, means for passing a cooling gas through said chamber, means for continuously feeding food through one portion of said chamber onto said conveyer, means controlled by the movement of the food and the conveyer for introducing the food onto the conveyer while preventing the escape of cooling gas from said chamber, means for continuously removing food from said conveyer at another portion of said chamber, and means controlled by the movement of the conveyer and the food for passing the food from the chamber while preventing the escape of cooling gas BENJAMIN S. FOSS.