US2587485A

US2587485A - Process and apparatus for treating hides

Info

Publication number: US2587485A
Application number: US595611A
Authority: US
Inventors: William O Kline
Original assignee: Frick Co Inc
Current assignee: Frick Co Inc
Priority date: 1945-05-24
Filing date: 1945-05-24
Publication date: 1952-02-26
Anticipated expiration: 1969-02-26

Description

w. o. KLINE 2,587,485

2 SHEETS-SI-1EET 1 mmvttw 1 W UMVIPW m- 3 5 8 3 WI mm 3.. mm w l lJ M508 52. mm 3 m h m 1.1.; F m m 9 mm a 2! m 2 \w u L 3 2 Feb. 26, 1952 PROCESS AND APPARATUS FOR TREATING HIDES Filed May 24, 1945 m S #K D D D om: A H C C Q K 1 .5 I. 5 a I N k a g T uumzuozou 55 v L mm 0? ow,

W. O. KLINE PROCESS AND APPARATUS FOR TREATING HIDES 2 SHEETS-SHEET 2 Feb.'26, 1952 Filed May 24, 1945 atented F 26 195 TATES William 0. Kline, Waynesboro, Pa assignor to Frlck Company, Franklin County, Pa.

Application May 24, 1945, Serial No. 595,611

16 Claims.

1 This invention relates to material treatment and more particularly to a method of and apparatus for drying, and the maintenance of the proper conditions of temperature and humidity during the drying process. The invention contemplates among other things the treatment or curing of hides or pelts in the manufacturing of leather.

This application is a continuation-in-part of my copending application Serial No. 437,261, now abandoned.

Various types of apparatus and various processes have been used in drying various and sundry materials, including hides, but improvement or advance in the art 'of drying has not been as rapid or pronounced as desired. Eiforts have been made to improve process, apparatus, and to obtain an improved product, as well as to reduce the amount of time required in the drying process.

The most commonly accepted present day practice of treating hides to dry them includes mechanical treatment where in the hides are subjected to softening and stretching mechanism which frequently produces serious strains on the fibers of the hides, particularly in the regions of scars. expensive, costly to maintain and requires skilled labor and involves considerable time in its use.

It is an object of the invention to provide an improved apparatus for drying which can be used not only for drying hides but in the treatment of other materials.

Another object of the invention is to provide an improved method by means of which drying may be simply and more rapidly accomplished and an end product of improved quality obtained.

A further object of the invention is to provideapparatus and process for an improved method of drying and capable of operation at improved efliciency.

When the apparatus and improved process are employed for treating animal skins or hides, the hides may be tanned, dyed, greased and placed on forms or frames for holding them extended. Thereupon they are subjected to a temperature sufficiently low to effect freezing of the contained water or moisture which forms ice crystals. These ice crystals break down the cellular structure and stretch and tear the individual fibers. The hides while thus frozen are subjected to drying air having a dewpoint lower than their temperature circulated and controlled as to temperature, humidity and velocity to effect drying by sublimation of the ice rather than evaporation of water or moisture. The resultant product is a This mechanical equipment is likewise 2 soft, pliable leather skin or fur of superior quality produced by a relatively low cost processing operation.

In practicing the invention an apparatus is provided which includes primarily a drying chamher and apparatus for maintaining the air in the drying chamber at the proper temperature and at the proper humidity, means being provided in the path of air travel for heating the air to increase its moisture absorptive capacity. As an adjunct to the drying chamber or place where drying is accomplished, auxiliary chambers for the supply and discharge of the material treated may be provided, and the proper refrigeration equipment to accomplish the desired result.

The material to be treated may be prepared for the drying room by freezing in any desired manner, as for example in a refrigerated supply chamber forming in effect a freezing chamber wherein the material is subjected to a cold dry stream ofair which freezes the water or moisture in the material before it is carried by a conveyor through the drying chamber. As shown in Fig. 1 the conveyor employed is an endless conveyor having portions in the drying chamber and the entrance and discharge chambers.

Means is provided for subjecting the material while in a frozen state to a controlled circulation of refrigerated air of the proper temperature and relative humidity and moving in a direction counter to the movement of the conveyor. Thus as the dry air contacts the moist material treated, moisture is picked up and the air is lowered in temperature with an increase in relative humidity. In order to maintain the air in a condition best suited for sublimation, the air is subjected to one or more reheating units or stages which increase or restore the temperature of the air and correspondingly decrease its relative humidity.

In order to operate with minimum energy and with maximum efficiency, the heating of the air that all the moisture and heat that can be absorbed in the drying chamber must come from the material treated.

The several parts of the apparatus are so related that the simplest and least amount of mechanism. is employed, thus, the cost is small as compared with other systems.

The various objects and advantages of the improved process and apparatus together with the preferred means for attaining such objects will become apparent in view of the following description taken in conjunction with the drawings, wherein:

Figure l is a diagrammatic representation of apparatus for carrying out the improved process, the'freezing and drying chambersbeing shown in sectional plan;

Fig. 2 is a view in elevation, partly broken away, of a preferred type of air cooler unit;

Fig. 3 is an end view of said unit; and

Fig. 4 is a vertical section through an alternative or modified form of freezing and drying tower.

Referring to the drawings in detail and particularly to Fig. l, a'freezing chamber is generally indicated at 10, a drying chamber at H and an unloading and reloading chamber or room at l2. A conveyor I3 is provided and has the starting run I3 thereof located in the freezing chamber III, the intermediate run (designated at l3) in the drying chamber II and the terminal run 13" in the unloading chamber 12. A baflle wall i4 separates the drying chamber from the terminal run of the conveyor and unloading chamber l2, to reduce air losses and restrict 'flow of air to the main run of said conveyor. The walls which form the chambers [0, H and 12 are heat insulated and substantially air and vapor tight.

In the preferred arrangement of the respective freezing and drying chambers, they are in conveyor-communication, and this also holds true with respect to the unloading and reloading chamber. A cold stream of air is continuously directed onto the hides in the chamber l0, after which the air is taken from said chamber and has its temperature raised to a predetermined degree and is then passed into the drying chamber and caused to move through the latter in a direction counter to the movement of the hides.

There are in effect three circuits or correlated systems to be considered, namely the air circulating system; the refrigerating or air-cooling system, and the heating system for maintaining the desired temperature and relative humidity of the air in the dryer. To more readily distinguish the respective systems or circuits, the air conduits are given the largest diameter, the heating system conduits next in diameter, and the piping for the refrigerating system smallest in diameter.

Referring first to the air circulating system,

this comprises an air cooler I! in which are mounted a plurality of evaporating finned cooling coil units l5a, l5b, lic and lid (see Fig. 2) placed in parallel in the air stream and constructed and arranged in a manner such as to permit any selected one of the units to be rendered inactive for defrosting purposes, as will be hereinafter more fully explained in connection with Figs. 2 and 3. Air from the cooler 15. is taken through conduit l6 having control damper or valve l6 therein and directed into the freezing chamber ill, from which it is taken through conduits l1, l1 having a blower or booster l8 therein to heat exchanger or reheater l9; and from the latter the air passes into conduit 20 and is directed into the drying chamber II at the point 2|. I

The air is taken from the chamber H at the point 22 and conducted by conduits 23, 23' having blower 24 therein back to the air cooler l5.

To assist in maintaining a substantially balanced pressure or a pressure slightly above normal atmospheric in the system and particularly in the freezing chamber l0 and drying chamber II, and to also control the pressure of the air passing to the reheater l9 and thence to the drying chamber, a bypass conduit 25 is provided between the conduits l6 and H and has adjusting valve 25' installed therein. Flow of air is from conduit l6 through damper 25' to conduit l1 and from conduit l6 through damper l6, freezing chamber I0, conduit l1, and fan I8 to conduit II. The full amount of air, of, for example, 23,000 C. F. M., constantly circulates through

conduits

22 and 23, fan 24, conduit 23, air cooler l5, conduit l5 up to connection made to 25, conduit ll' following connection made from 25, reheater l9, conduits 20 and 2|, and drying chamber II. If desired for freezing purposes, part of full amount of air, of, for example, 10,500 C. F. M., would circulate through conduit l6 following connection of 25, damper l6, freezing chamber l0, conduit ll, fan l8, and conduit l1 up to connection of 25. The air pressures in inches of water during operation in different parts of system would, for illustration, be as follows: drying chamber II is 0", conduit 23 is 0", conduit 23 is 3", conduit I6 is 2" due to 1 friction loss in air cooler l5, damper it reduces 2" pressure in conduit 16 to 0" pressure for freezing chamber l0, conduit I1 is 0", fan l8 boosts 0 in I! to 2" in H, conduit 25 (on both sides of damper 25) is 2", damper 25' acts as pressure relief from IE to ll; .since full amount of air is not used in freezing chamber, conduit I1 is 2", and conduit 20 is 1 due to friction loss in air reheater. In this all spaces mentioned at 0" would be at atmospheric pressure or slightly above.

Any desired type of refrigerating system for refrigerating the air may be utilized. It is pre ferred, however, to utilize a multi-stage system such as that disclosed in the copending application of Frank R. Zumbro, Serial Number 423,683,

cooler coil 35 to expansion valve 36, whlch supplies refrigerant to the evaporator or cooling coils l5.

As heretofore noted, means are provided for controlling the temperature and relative humidity with conditions encountered, the following being v of the air circulating through the drying chamber II and ,thus maintain the air in the most efficient condition to effect drying of the frozen hides by ice sublimation, or by a change from the solid directly to the gaseous state, and also reduce the quantity of air required. Such means as here shown comprises a plurality of heaters 31, 31' through which is circulated 'a' suitable non-freezing fluid or solution such as brine. The brine-circulating system includes a brine tank on heater or heat-exchanger unit 38 to which is connected an outlet conduit 39 which communicates with

conduits

40 and 4|, the former serving to conduct the heated brine to the heaters 31 and the latter leading to reheater l9, which as heretofore'noted is in heat-exchange relation with the air taken from the freezing chamber and/or air cooler [5 by conduits ll, I1 and The brine from the heaters 31, 31' returns through conduits 42 and 43 to the brine heater 38, a circulating pump 44 being installed in the conduit 43. The brine flowing through the conduit 4| and heat-exchanger I9 is returned to the heater 38 by means of conduits 45 and 43.

The cooling medium for the condenser 33, which may be water, is brought in through conduit 46 and flows through coil 4'! located within the brine tank or heater 38 and thence through conduit 48 to the condenser 33, from which it is discharged to the main or other suitable takeoff through conduit 49.

It will be seen that brine from the heater 38 is caused to circulate by pump 44 through pipe or conduit 40 to the air heaters 31, 31', etc., from which it returns to the said heater through pipe or conduits 42 and 43. Brine also circulates from the tank or heater 38 through

conduits

39 and 4| to the heat exchanger l9'and thence back to the tank or heater 38 to conduits 45 and 43. The brine in the tank or heater 38 will naturally be relatively cool due to the fact that heat has been extracted from the brine in the units 31 and the incoming condenser water will normally be of a higher temperature than the brine temperature, so that there is an exchange of heat from the water to the brine. Thus the air is indirectly heated by the incoming condenser water, and this results in an extraction of, heat from the water and a consequent lowering of its temperature so that it is in a better condition to effect its refrigerant-condensing function. This in turn results in lower condensing pressure requirements in the refrigerating system and a consequent reduction in power requirements for the refrigerating plant as well as a reduction in the size of the required compressor units. Another advantage in utilizing a non-freezing fluid such as brine for transferring the heat of the incoming condenser water to the air is that there is no danger of freezing the fluid in the coils of the heaters 31 which are subjected to air well below freezing temperatures. While relatively warm water might be circulated directly in the units 31 without freezing if kept in constant motion, yet'should circulation be halted for a relatively short period of time, the water would freeze with resultant damage to the coils.

The operation of the herein disclosed process and apparatus may be varied in accordance given by way of example: I V l The hides or leather to be processed are usu-' ally first tanned, dyed and greased and stretched on a frame or othersuitable support. The hides the hides will be frozen by the time they'pass into the drying chamber H. (As an alternative, the hides may be frozen in a separatefreezing chamber and then loaded onto the; conveyor in the chamber In in which event the laltter would be considered a loading chamber.)'"" Freezing expands and distorts the cellular structure of the hides, or may be said to stretch and tear the interlocked and interconnected fibres of the hides, contributing to the subsequent softness and pliability thereof. The water content of the hides prior to freezing as well as the degree and/or rapidity of freezing has an important bearing on the resultant softness and pliability of the leather. Thus, for example, slow freezing produces relatively large ice crystals and thereby increases the stretching action on the fibres. It is important therefore that the freezing temperatures be properly controlled, and the present apparatus well adapts itself to such control.

When the hides move through the drying chamber ll, they remain in a frozen condition, the temperature and relative humidity of the air being controlled or adjusted to effect drying by ice sublimation rather than by melting of the ice and evaporation of the resultant moisture. Thus the air moving in at point 2| should be properly conditioned so that it is of low relative humidity and at a temperature below the freezing point of water to carry out this function. The temperature of the brine circulating through the heaters 31, 31' should be such as to maintain the air in the desired condition by raising the temperature of the air and, therefore, its moisture absorbing capacity, but not raising its temperature above the freezing point of water. This combination of freezing and drying by ice sublimation has an important bearing on the resultant quality of the hides. Controlling the air in this manner also results in a marked reduction of the quantity of air required for circulation through the drier.

The air circulating system, the air heating system and the refrigeration or air-cooling system are all in heat-exchange relation. Thus the air flowing through the freezing chamber ID from the cooling coils of evaporator I5 is well below freezing temperature, but when it leaves the freezing chamber it may be raised a very few degrees and when it passes through the heat-exchanger I9 on its way to the drying chamber H, it has a certain amount of heat added thereto from the brine circulating in the brine heating system; and likewise the brine as it flows to the

heating units

31, 31 supplies heat so that there is an exchange of heat from this brine to the air.

By providing a controlled by-pass between the conduits l6 and I1 and separate fans or pumps for withdrawing air from the freezing chamber and from the drier, the pressure in the various parts of the system may be selectively controlled. Thus the blower 18 in conjunction with the damper I6 may be adjusted to maintain the tions may be maintained active.

air pressure in the freezing room as close atmospheric as possible, while the blower 24 may be ad usted to maintain the desired velocity of the air circulating through the drying chamber. It is important that the velocity of the air circulating through the drying chamber be under ready control in 'order to obtain the proper degree of drying and to bring the proper quantity of dried air in contact with the hides. The bypass 25 permits a more nearly balanced pressure in the circulating system between the freezing and drying chambers.

In this respect, attention is directed to the fact that it is of advantage to maintain the pressure within the freezing and drying chambers at approximately atmospheric since vapor will readily migrate. Infiltration of moisture is further counteracted by lining the drying chamber as well as the freezing and unloading chambers with vapor proof material, and also by providing the doors for said chambers with a non-freeze and non-evaporating liquid seal.

Figs. 2 and 3 illustrate a preferred type of air cooler l5. The air comes in through header 50 and divides and passes into chamber 5| in which are mounted the respective coil units I511, 151), I50 and id. These coils are preferably of the fin type operated by flooded ammonia direct expansion with the respective sections in parallel in the air stream. The sections are each mounted in an open-ended casing which at its upper end is provided with a trough 52 in which is a non-freezing liquid of any suitable type. Each casing is provided with a hinged door 53 which constitutes an air valve at the entrance end of the casing and is formed with flanges 53 which project into said trough to eifect a liquid seal. The door valve 53 is mounted on a hinge member 54, note Fig. 3, whereby the door may be swung clear of the coil casing. In this manner, any number of sec- Also the remaining section or sections are being defrosted and which defrosting action may be controlled automatically. As the sections [5a, l5b, I50 and l5d of the cooling element l5 are maintained active or rendered inactive, the cooling effect on the air passing through the cooling element I5 is modified to maintain a substantially constant outlet temperature and the desired humidity. Fig. 2 shows the first unit on the left being defrosted with the valve cover 53 down to prevent air from passing over the coils, thecovers of the remaining coils being up so that the latter are.

exposed to the air stream. This arrangement is of particular advantage in asystem of this kind, since there may be considerable moisture condensed and frozen on the respective cooling coils.

Air may be taken from the main cooling unit by means of exhaust manifold 55.

Fig. 4 illustrates a modified form of freezing and drying chamber or tower. In this instance, the freezing chamber is indicated at 56, the drying chamber at 51 and the unloading chamber at 58. A conveyor 58 is provided and makes a continuous circuit through the respective chambers. The drying chamber is preferably divided into a series of zones by vertically extending baflie walls 60, BI and 62. This permits a more compact arrangement which may be desirable for certain plants.

It will be understood that no attempt has been made herein to bring out all of the features of advantages of the improved system and apparatus, and further, that certain changes in procedure as well as in construction and design of the apparatus may be adopted without departing from the spirit or scope of the invention as dehned by the appended claims.

What is claimed is:

1. apparatus 101' drying material at sub-freezing temperatures comprising an air cooler for lowering the dry bulb temperature or the air below freezing and the dewpomt below the temperature of the material to be dried, refrigerating means for chilling said cooler incluomg a condenser and means to supply said condenser with a cooling medium, an air heating unit for raising the temperature of the air to a point below freezing, means to convey air from said air cooler to said air heating unit, a drying chamber, a duct connecting said heating unit with said drying chamber, an air outlet duct from the drying chamber leading to the air cooler, a fan in said latter duct, a heat exchanger for cooling said condenser cooling medium prior to its use in the condenser, means to circulate brine in a closed circuit through said air heating unit and said heat exchanger, and means 101' conveying said material through said drying chamber.

2. Dryingby sublimation comprising subjecting material to be dried to how 01' air having a dewpoint lower than the temperature of the material and a dry bulb temperature below freezing to cause absorption of moisture from the material by the an, heating the air as it approaches saturation to increase its sensible heat and hence its ability to further absorb moisture without heating the air enough to increase its temperature above the freezing point.

3. Drying by sublimation comprising subjecting material to be dried to a flow of air having a dewpoint lower than the temperature of the material and a dry bulb temperature below freezing to cause absorption of moisture from the material by the air, heating the air as it approaches saturation to increase its sensible heat and hence its ability to further absorb moisture without heating the air enough to increase its temperature above the freezing point, and limiting the amount of heat absorbed so that the sensible heat of the air will be maintainedsubstantially constant.

4. Drying by sublimation comprising compressing refrigerant and condensing the same with the aid of a cooling medium, utilizing the condensed refrigerant to cool air to a temperature below freezing, subjecting material to be frozen to said air, utilizing heat from the cooling medium before it is employed to effect condensation of the refrigerant to increase thesensible heat of the air and its ability to absorb moisture without heating the air enough to increase its temperature above the freezing point, passing the air over said material to effect drying; and restricting the heat absorbed so that the sensible heat of the air will be maintained constant.

5. Drying by sublimation comprising compressing refrigerant and condensing the same with the aid of a cooling medium, utilizing the condensed refrigerant to cool air to a temperature below freezing, passing the air over material for A 9 of below freezingair by heat derived from the cooling medium is accomplished with the aid of a closed fluid circuit containing a circulating medium which will not freeze in the drying chamber, said circuit having one portion in heat transfer relation with the cooling medium and another portion in heat exchange relation with the drying chamber.

7. In the art of drying, the improvement which comprises abstracting heat from material in a freezing-zone to bring it to a temperature below freezing, passing the frozen material through a drying chamber, refrigerating air to a temperature below freezing with the aid of a refrigeration system having heat absorbingrmeans, util zing a cooling medium for condensing the refrigerant, circu ating the air in a substantially closed cycle for successive flow from the heat absorbing means to the freezing zone, and thence through the drying chamber back to the heat absorbing means, and effecting the heating of the below freezing air in the drying chamber by heat derived from the above cooling medium prior to its use by the refrigeration system, the heating of the below freezing air being insuflicien to bring its temperature above freezing.

8. In apparatus for drying by sublimation walls of low thermal conductivity defining a drying chamber, an unloading and reloading chamber and a freezing chamber, means for supplving air at a temperature below freezing into said freezing chamber so that material to betreated will be frozen therein, an endless conveyor located in said chambers, means for withdrawing air at a temperature below freezing from said freezing chamber, means forming communication between said supplying and withdrawing means, means for heating the air drawn from the freezing chamber at a temperature below freezing to a slightly higher temperature below freezing and introducing such air into the drying chamber and means for withdrawing air approaching freezing temperature from the drying chamber from a position remote to the place where air is admitted to the drying chamber and passing said air through an air cooler and into the air supply line to the freezing chamber.

9. In the art of treating hides to render the same soft and pliabe, the process which consists in subjecting a batch of stretched hides to below-freezing temperatures in a freezing chamber. conveying the hides while in a frozen condition through a drying chamber, circulating air in a substantially closed cycle through the freezing chamber and thence through the drying chamber, refrigerating the air by a refrigeration system having heat absorbing and heat rejecting means prior to its passage into the freezing chamber, and utilizing heat from means used to cool the heat rejecting means to heat the air in the drying chamber.

10. In the art of treating and drying frozen materials, the process which consists in freezing the material in a freezing chamber and thereafter conveying the material through a drying chamber, refrigerating the air prior to its passage into the freezing chamber by means of a refrigeration system having a water cooled condenser, circulating the air in a substantially closed cycle from the freezing to the drying chamber, and utilizing the heat extracted from said condenser water for heating the air in the drying chamber.

11. An apparatus for processing hides comprising a freezing chamber and a drying cham- 10 her, means for conveying hides through said chambers, means for circulating air in a substantially closed cycle through said freezing chamber and thence through said drying chamber, means for refrigerating air including a condenser prior to its entrance into the freezing chamber, means for heating the air circulating through the drying chamber including one or more heaters and a substantially closed circulating system for circulating "a liquid'having a lower freezing point than waterthrough said heaters, said liquid having a' temperature higher than that of the air entering the drying chamber, and means for circulating a condensing-fluid in-heat exchange relation with said liquid to thereby in-- directly heat the air of the dryer by heat in connection with the refrigeration system.

12. Apparatus for processing hides comprising a freezing chamber and a drying chambeiymeans for conveying hides through said drying chamber, a substantially closed air circulating system including a series of interconnected ducts for circulating air first through the freezing chamber and thence'through the drying chamber in a direction counter to movement of the hides through the latter chamber, a refrigeration system ineluding an air cooler for refrigerating the air prior to its passage into the freezing chamber, means for maintaining the air in the freezing and drying chambers at slightly above atmospheric pressures, and means for controlling the velocity of air circulating through the drying chamber.

13. An apparatus for processing hides comprising a freezing chamber and a drying. chamber, a conveyor for conveying hides from the freezing chamber to and through the drying chamber, an air circulating system comprising a series of interconnected ducts arranged to circulate air first through the freezing chamber and thence throu h the drying chamber, means for re rigerating the air prior to its passage into the freezing chamber, the air being circulated through the drying chamber in a direction counter to the movement of the hides through the latter chamber, a heating system including a plurality of heaters disposed in the drying chamber in longitudinally spaced relation to control the tem erature and relative humidity of the air circulating throu h the drying chamber, said heat ng system including a heater and a closed vessel and interconnected conduits for circulating a liquid having a freezing point below that of water and a tempe ature hi her than that of the air enterin the drvin chamber from said vessel to said heaters. said refri eration s stem including a condenser and a heat exchan er having a coi therein for conducting condensing fluid to the condenser, said coil being disposed in said vessel to therebv extract heat from the condenser fluid and utilize such heat for heating the non-freezing heating fluid.

14. Hide drying apparatus comprising a drying chamber throu h which hides are adapted to be passed for drying same, a freezing chamber at the entrance end of the drying chamber, means for supplying the freezing chamber with refrigerated air, means for withdrawing the air from the freezing chamber and introducing it into the drying chamber said air then having a dewpoint lower than the temperature of the hides, means for producing circulation of refrigerated air through said chambers, and means for maintaining a pressure differential between said chambers.

ing chamber through which hides are adapted I to be passed for drying same, a freezing chamber at the entrance end of the drying chamber, means for supplying the freezing chamber with refrigerated air, means for withdrawing the air from the freezing chamber and introducing it into the drying chamber at a point remote from the freezing chamber said air then having a dewpoint lower than the temperature of the hides, means for producing circulation of refrigerated air through said chambers, means for maintaining a; pressure differential between said chambers, and means for maintaining the freezing chamber at substantially atmospheric pressure to minimize infiltration of outside air or exfiltration of refrigerated air.

16. Apparatus for drying hides and like products at sub-freezing temperatures comprising an air cooler, a refrigeration system for chilling said cooler including a condenser and a supply of condenser cooling medium, a freezing chamher, an air conduit communicating the air cooler with the freezing chamber, a damper in said conduit for controlling air flow and pressure to the freezing chamber, an air reheating unit, an air duct having a blower therein for withdraw- .ing air from the freezing chamber, an air duct leading from said blower to said unit, a bypass duct between said air conduit and the air duct leading from the blower" to the reheater, a hide drying chamber, a duct connecting the v 12 drying chamber, a brine circulating system including a heat exchanger for cooling the condenser cooling medium, by means of said brine and said heaters, a. circulating means for the brine system, and means whereby hides may be conveyed from the freezing to the drying chamber and in a circuitous path through said latter chamber.

WILLIAM O. KLINE.

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

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