US2552832A - Cold treating method and machine - Google Patents

Description

May 15, 1951 P. M. AHLSTRAND ET AL 2,552,832

cow TREATING METHOD AND MACHINE Filed April 17, 1946 2 Sheets-Sheet 1 INVENTORS PH/LL/P M. AHLSTRAND 4/5 ge-0905 w. PA TCH, JR.

ATTORNEY M y 1951 P. M. AHLSTRAND ETAL 2,552,832

cow TREATING METHOD AND momma Filed April 17, 1946 2 Sheets-Sheet 2 I INVENTQRS PH/LL/P M. AHLSTRAND ea-090E w. PA TCH, JR.

ATTORNEY and compact refrigerator.

Patented May 15, 1951 COLD TREATING METHOD AND MACHINE Phillip M. Ahlstrand, Kenmore, and George W. Patch, Jr., White Plains, N. Y., assignors, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Application April 17, 1946, Serial No. 662,700

15 Claims.

This invention relates to a method of and apparatus for chilling objects to a low temperature and has for an object to provide a method and device of this sort which is simple and easy to operate. A further object is to provide a portable Another object is to provide such a device adapted for cooling objects of different sizes.

Previous suggestions for chilling objects have been described in the patent of McCandless et a1., 2,487,821, dated November 15, 1949, for Method of and Apparatus for Cooling and Dispensing Objects and the patent of Ahlstrand 2,534,334, dated December 19, 195 0, for Cold Treating Method and Apparatus. These previous suggestions are not as well adapted for cooling objects of different sizes as is the present invention. Such earlier suggestions also depend somewhat on thermal conductivity between the object and the walls of a tube. In the present application heat transfor between the tube Walls and the objects is largely by convection currents of gas. The machine or apparatus of the present invention is more compact therefore it is better suited to be portable about a manufacturing plant. Where the prior suggestions mentioned contemplated objects moving intermittently through the cooling tube the present improvement contemplates the objects being held substantially stationary in the cooling tube until time for their removal. Another difference is the practical elimination of the pro-cooling method and apparatus before the objects are received Within the cold tube surrounded by liquid refrigerant.

Referring to the drawings:

Fig. 1 is a diagrammatic representation of a machine embodying the present invention;

Fig. 2 is a perspective of the top portion of the refrigerator with one of the object holding cartridges partially elevated;

Fig. 3 is a vertical section through a portion of the refrigerator; 1

Fig. 4 is a section through one of the object holding cartridges;

Fig. 5 is a section on the line '5--5 of Fig. 4.

A liquid refrigerant tank [0 is provided with a plurality of wells, guides,jcompartments, or tubes H and [2 extending into the liquid adjacent the bottom of the tank Hl for the purpose of receiving objects to be cooled. The portion of these tubes within the liquid refrigerant tank is preferably formed of a material such as copper having a high thermal conductivity while the portion of these tubes between the upper Wall of the casing and the copper portion is of a metal such as stainless steel or silicon bronze having much poorer thermal conductivity than the copper so that less heat will be conducted through the outer casing to the liquid refrigerant. A

cover I3 is provided for each such well or tube,

the cover being attached to and removable with an object receiving cartridge 14, each such cartridge having a plurality of object supporting levels or shelves l 5 for the work to be cooled. As shown in Figs. 4 and 5 the shelves i5 are connected to and supported by arcuate strips IE formed preferably of stainless steel to which the shelves are soldered, Welded or otherwise secured. Above the strips l6 and shelves i5 is a top part it of each cartridge also constructed of stainless steel or of appropriate thermal insulating material to which the cover I3 is aiiixed. The copper portion of the guide tubes is indicated by the numeral IS in Fig. 3 while the metallic stainless steel bellows 19 between the top of the casing and such copper tubes serve to reduce heat conduction from the outer casing to the copper and also functions as an appropriate expansion joint due to the wide temperature variations through which the liquid refrigerant tank and copper tubes pass when in normal operation and when being defrosted and not used. A screw threaded projection 2% extends above each cover 13 for the purpose of having a thumb nut 2i fit over such projection for threaded cooperation therewith and raising any one of the covers and its cartridges as the elevating boom 22 is raised. The mechanism for actuating the boom 22 may be fluid pressure, ei ctromagnetic, counterweight or manually operated. To avoid holding more of the chilled objects than needed out of the refrigerator each cartridge is preferably given a step by step movement in unloading, the unloading taking place from the top in sequence toward the bottom. To reduce the loss of vaporized refrigerant while loading a withdrawn cartridge or loading a cartridge in a step by step movement, the preferred practice is to keep a loaded spare cartridge available for replacement and direct insertion without a step by step movement as soon as a cooled cartridge has been unloaded as described. As shown in the drawing the end of the boom extending over the covers is provided with 4 sockets so that any one or more of the 4 cartridges may be elevated though ordinarily only one cartridge at a time is raised.

An outer casing 23 surrounds the liquid refrigerant tank It] and is spaced therefrom the intervening space being filled preferably with a thermal insulating material 24. A filling pipe 25 and appropriate cover therefor provides for the easy filling of the tank with liquid refrigerant, the upper end portion of the filling opening is covered over by the raised casing portion shown on the left side of Fig. 2 between the boom support and the covers it. Within the liquid tank IE3 is provided a float mechanism, not shown in the drawing for clarity and because any conventional type of float mechanism adapted for the low temperatures encountered is believed appropriate, such mechanism being connected to a liquid level indicator located within the housing 26. Three signal lights 2? are shown on the top of the machine casing in Fig. 2, a green light indicating normal refrigerating operation,

an amber light indicating defrosting, and a red I light indicating the liquid level 28 in the tank it to be above a predetermined amount.

Due to the substantial temperature changes which the guide tubes l I and I2 undergo between normal operation and defrosting the cartridge strips it preferably do not have a tight or heat conductive fit or engagement with the walls of the guide tube but instead heat is transferred 2.

from the objects to the tubes H and [2 by convection currents of cold gas. As shown in Fig. 5 each shelf !5 is provided with a number of perforations. As the objects lose their heat when placed within the refrigerator such heat becomes transferred to the copper tubes l8 and the liquid refrigerant causing the refrigerant to be vaporized by the heat absorbed. The vaporized refrigerant rises and under the influence of either or both a slight pressure in the refrigerant tank and suction in the drawing off pipe, such vaporized portions of cold gas pass into the space shown most clearly in Fig. 3, thence into the chamber 38 through the perforation 3| in the wall 32 where their direction is changed in passing down around the lower end portion of the baflle 33 and thence up over the top of the pipe as leading the cold gas through from the liquid into a space 35 in the low header 36. The cold gas then rises through each of the guide tubes H and i2, entering the same through perforations shown in Figs. 1 and 3 as being at the base of each such guide tube. The cold gases rise through each such guide tube and pass out through perforations 3! into the upper header 38 from which such gases are passed through the outlet duct 39 and a suction pump 46. An eX- pansion joint of stainless steel bellows M is provided near the bottom of the casing or housing from which the passage 4! leads the cold gas along heaters and 63 inside walls of the gas passage. From the heaters the cold gas passes as illustrated by the arrows to the right for mixture with a large amount of air coming through the intake 43 and passing through the suction fan 44 for its discharge into the atmosphere at the outlet 35. The addition of a large volume of air to the refrigerant vapor being discharged to the atmosphere prevents undesirably high concentrations of the refrigerant vapor in the atmosphere adjacent the discharge opening 45.

To safeguard the liquid refrigerant tank It and casing 23 against generation of dangerous pressures therein, a pipe 35 leads from the pipe 34 to a frangible disc 41 adapted to break when pressure within the tank exceeds a predeterminedlow value such as 3 or 4 lbs. per sq. inch. A similar disc @8 is adapted to rupture in event of any substantial pressure being generated within the casing 23. For drawing off any condensed refrigerant or other liquid from the bottom of the lower header 35, a drain pipe 49 is provided having therein a valve indicated, held normally closed. A similar pipe '50 with valve leads from the bottom of the liquid refrigerant tank H]. Due to the suction created by the fan 44, when one of the covers I3 and cartridges [4 are raised air may be drawn into the upper portion of the guide tubes II and i2 and out through the perforations 3? although such warm air drawn in will be in comparatively small amount.

Due to the formation of frost in the upper portions of the guide tubes El and i2 and elsewhere it may from time to time be desirable to defrost the machine after the liquid refrigerant has been used up or drawn off. To accomplish this a handle 5% is rotated to close the butterfly valves 52 and 53 and open the valve 54 which causes air to be drawn in through the intake 43, blower M, thence through the passage containing valve 54 to the plate heater 42. During the defrosting operation other heaters 55 and 63 surrounding the pipe through which the defrosting medium is passed, are in operation so that the incoming air is heated by both internal and external heaters before it passes up the passage 4i through the duct 39 into the upper header. 38, guide tubes 5 l and I2 and into the lower header 36. During such defrosting the covers it should be opened or raised at least long enough to defrost the portion of the guide tubes II and i2 above the perforations 31. When the covers III are closed the warm air passes down the guide tubes into the header 36 and out its drain pipe as when the valve in drain pipe 49 is open.

When the liquid level approaches a predetermined high amount of overflow of the liquid refrigerant occurs through the pipe 55 into an au'xiliary reservoir 51 causing a thermostat within the casing 58 to'be actuated in response to the cold liquid, thereby closing the circuit through the red lamp. Preferably, the reservoir 57 should be placed near the outer wall of the casing so that liquid in the reservoir 5! will slowly evaporate and pass back into the space above the liquid level in the tank IE This thermostatic responsive indicator or red light operates only when the liquid level exceeds a desired amount. If the auxiliary reservoir 51 were located close to the refrigerator tank id too long a time might be consumed before the small amount of refrigerant had vaporized which would mean the red lamp would be indicating an excessive liquid level for too long a time.

A thermostat in the thermal well 59 controls the circuits 62 and 62a. to the heaters 55 and 63 and prevents their getting too hot. Another thermostat in the thermal well 6! controls the circuit 60 to the heater 152 during defrosting. As the butterfly valves are operated by the handle 55 a switch 6d operates to close circuits through three heaters and the amber or defrost light when such butterfly valves are in the defrost position described above. When they are in normal operating position illustrated then a switch E35 closes the circuits through heaters 55 and 63 and the green light indicating the machine to be in condition for normal operation.

Since the cartridge is normally out of contact with the side walls of the guide tub-es or wells a centering guide post 66 is provided, the upper end portion of the post being received within the socket G? of the cartridge as shown in Figs. 1 and 4.

. Post 66 may be eliminated when objects having solid centers are to be cooled.

A Packing 68 is secured to the covers'to prevent loss of cold-gas when the covers are closed. A control lever 69 operates a fluid pressure piston and cylinder Ill actuating the boom 22. The fluid pressure cylinder and specific mechanism for actuating the same is no part of the present invention but is described and claimed in the copending application of R. F. Hinschlager, Serial No. 662,889, filed April 17, 1946, for Increment Mechanism.

When using nitrogen there is not the same objection to the cold gas escaping to the atmosphere without being heated so that the heaters 55 and 63 no longer become as necessary in normal'oper'ation but their use for normal operation and also with heater 42 in defrosting is preferable.

As shown in Fig. 5 the individual shelf parts [5 of the cartridge are each provided with a plurality of perforations l2. Bent-up retaining lip portions 13 assist in holding an object in position on the shelf to prevent it coming out of the shelf by the way it was inserted. The objects or work to be chilled in Fig. 1 as shown are a plurality of discs or rings M although other types of work may be chilled and. the spacing of the shelves made to conform to the particular type of work used. The outside heaters 63 and 55 are normally used with oxygen whereas heater 42 comes into operation only in defrosting. Duringthe defrosting operation the air coming into the wells and liquid tank is heated preferably well above the atmosphere, such as from 100 F. to 125 F.

Among the advantages of this invention may be mentioned the adaptability of the refrigerator for different shapes and sizes of objects to be chilled. Anothernoteworthy feature is its adaptability for smaller plants where a portable machine is useful. The heat is transferred from the objects to the conductive walls of the wells or guide tubes by a cold gas. Another advantage is the possibility of using adapter tubes within the tubes H and I2 when the work pieces to be chilled are of much smaller diameter thanv the inside of tubes II and I 2, to provide guides for holding the work yet permitting the passage of cold gas through the adapter tubes for the same intimate contact with the work.

' We claim:

1. A machine for cooling a number of objects comprising a liquid refrigerant tank, a thermally conductive tube extending from an upper portion of said tank to below a liquid level in the tank and adjacent the bottom thereof, means for passing cold gas through said tube, and a removable object holder in said tube comprising a plurality of spaced shelves for said objects.

2. A refrigerator comprising a housing, a tank for liquid refrigerant therein, insulating material between the housing and tank, an object receiving tube extending from the housing through the insulating material into the tank from above a liquid level therein and to the opposite side of said tank, a second tube leading from the upper portion of said tank through any liquid therein to said opposite side of the tank for passing vaporized liquid refrigerant through any liquid in said tank, and a passage connecting the ends of the first and second mentioned tubes adjacent said opposite side of the tank for passing said vaporized refrigerant into the first tube.

3. A refrigerator comprising a housing, a liquid refrigerant tank in the housing, a plurality of tubes extending from the top of the housing downward into said tank to below a liquid level in the tank and adjacent the bottom thereof, a

header connecting the lower end portions of said tubes, a cold gas conduit leading from the upper portion of said tank to said header, a second header adjacent the upper portion of said tank surrounding said tubes, a pump for drawin off cold gas from the second mentioned header, said tubes each being provided with a perforation in their upper portions into said header, covers for the top ends of said tubes, and multi-platformed object carriers for said tubes.

5. A frigerator comprising a liquid refrigerant tank, a plurality of object cooling tubes extending into said tank, a cold gas header connecting the ends of said tubes remote from the object input end thereof, a second cold gas header surrounding the tubes adjacent the object input end of the tubes, the tube walls within the second header being perforate, a cold gas conduit leading into a space surrounded by but sealed from the second header while in contact with the upper portion of the tank and connected with the first header whereby vaporized liquid refrigerant may flow through said conduit, first header, tubes and second header in the order mentioned.

5. A refrigerant comprisin a liquid refrigerant tank, an object guide tube extending from an upper portion of said tank downwardly in a substantially straight line into said tank to below a liquid level in said tank and adjacent the bottom thereof, an object holder movable into and out of said tube at its upper end portion, and connections for passing vaporized liquid refrigerant through the portion of said tube immersed in any liquid refrigerant.

6. The method of operating apparatus for chilling an object with a liquid refrigerant vaporizable far below atmospheric temperature which comprises vaporizing such refrigerant passing the vaporized refrigerant in contact with said object to be cooled, drawing off the vaporized refrigerant from around said object to a distance from the location of the object being cooled, and heating the vaporized refrigerant thermally remote from said object and before diluting the same with air.

7. A refrigerator having a tank for liquid refrigerant vaporizable far below atmospheric temperature, means for passing vaporized refrigerant in contact with the object to be cooled, means for. heating the vaporized refrigerant after it has passed contiguous the object to be cooled and before it is discharged to the atmosphere, and additional means for heating gas blown into the refrigerator for defrosting the same.

8. Apparatus for cooling an object comprising a liquid refrigerant tank, a casing outside the tank, thermal insulating material between the casing and tank on at least some sides, a well in which an object may be cooled by vaporized refrigerant from said tank, a cover for said well. the axis of said well being displaced laterally from the axis of said tank, a passage for directing vaporized refrigerant from the tank above the liquid level into the lower portion of said well, and a discharge passage for vaporized refrigerant from an upper portion of said well leading the vaporized refrigerant laterally away from the well below said cover.

9. A method of operating a cooling apparatus comprising inserting an object into a guide tube, passin a body of cold gas through said tube, removing said object from said tube by moving said body in an opposite direction to the movement of the object into said tube, defrostgreases lng the inside of said guide tube by heating ea.

gas and moving it th'roug'h said tube in'an'opposite direction to 'the passage of cold gas through said tube after stopping thesupply "of coldgas to said tube.

10.;A liquid level indicator for a refrigerator comprising a tank for a liquid refrigerant, an overflow pipe from said tank, an auxiliary reservoir connected to said overflow pipe and located away from said tank to receive heat independently of said tank, a return pipe for vaporized refrigerant from said reservoir to an upper portion of said tank, said return pipe being in addition to the overflow connecticmand a signal for indicating the presence of liquid refrigerant in said reservoir. 11. Apparatus for cooling an "object com ris ing a tube in which said object is placed, a tank for liquid refrigerant surrounding said tube throughout a large portion of its length,asecond tube leading froman upper portion of said tank to the lower portion of said first mentioned tube for conveying vaporized refrigerant into said first tube, saidfirst tube being of heat conductive material whereby heat absorbed by it might be extracted "from it by convection currents of liquid refrigerant in said tank, an outlet passage for vaporized refrigerant'from an upper portion of said first tube, a cover for said first tube, and means by which said object may be removed through the upper portionof said first tube when thecover is removed.

12. Apparatus for cooling an object comprising' a liquid refrigerant tank, a casing outside said tank, thermal insulating material between the casing and tank on at least some sides thereof, a well within said casing in which an object may be cooled by vaporized refrigerant from said tank, a cover for said well, the vertical axis of said well being laterally displaced from the vertical axis of said tank, a passage for-directing vaporized refrigerant from an upper portion of 'said tank above a liquid level therein to an end portion of said well, and a discharge passage for vaporized refrigerant leading from an opposite end portion of the well to that into which said vaporized refrigerant enters the well.

13. A refrigerator comprising a li uid reirigerant tank, a casing outside or and ther mally insulated from said tank, an auxiliary overflow reservoir for liquid refrigerant from the tank when the liquid level reaches a predetermined height, anoverfiow pipe between said tank and reservoir, a signal visible from -outside' s'aid easing for indicating the presenceof liquid'in said reservoir, said reservoir being located to receive heat from said casing for'vaporizing liquid refrigerant therein, and a vapor line connecting an upper portion of the reservoir with an'upper portion of said tank for the return of vaporized refrigerant to the tank.

-14. A refrigerator having a compartment for an object to be cooled, means for passing cold gas around said object, a dischar e conduit for leading cold gas from said compartmentout of the refrigerator during the passing of cold .gas around said object, and means for defrosting said refrigerator by moving warm air through said discharge conduit into said compartment, said defrosting means including a heater in said discharge conduit.

15. A refrigerator including a compartment for an object to be cooled, a tank adapted to hold liquid refrigerant, a thermally insulated casing around said tank and compartment, a conduit for conveying vaporized refrigerant from an upper portion of said tank into said compartment, a conduit for conveying vaporized refrigera'nt from said compartment to the outside of said casing, a blower 'for'dir'ecting warm gas into said compartment for defrosting the same, an outlet passage for warm air from said compartment, and means for closing said outlet passage during cooling operation of the refrigerator,

PHILLIP M. AHLSTRAND. GEORGE W. PATCH, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 227,477 Booraem 1-11-- May 11, 1880 1,199,819 Phillips Oct. 3, 1916 1,592,946 Knight 1 July 20, 1926 1,681,399 'Copeman Aug. 21, 1928 1,685,047 Fuller Sept. 18-, 1928 1,708,235 Nug'ent Apr. 9, 1929 2,169,284 Ploeger Aug. 15, 1939 2,254,420 Cleveland Sept. 2, 1941 2,304,211 sparrow Dec. 8, 1942 2,382,084 Mathews Aug. 14, 1945 2,384,210 Sunday Sept. 4, 1945 2,447,249 Hill Aug. 17, 1948 2,447,606 Wine 1 Aug. 24, 1948 McCandless e't-al. Nov. 15, 1949

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