US2706620A

US2706620A - Heat exchanger

Info

Publication number: US2706620A
Application number: US223483A
Authority: US
Inventors: Roy R Graves
Original assignee: Graves-Stambaugh Corp
Current assignee: Graves-Stambaugh Corp
Priority date: 1951-04-28
Filing date: 1951-04-28
Publication date: 1955-04-19
Anticipated expiration: 1972-04-19

Description

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Car '/f' A TTRNE YS United States Patent C) HEAT EXCHANGER Roy R. Graves, Valparaiso, Ind., assignor to The Graves- Stambaugh Corporation, a corporation of Delaware Applicatie April 2s, 1951, serial No. 223,483

2 canins. (ci. 257-246) This invention relates to heat exchangers and this application is a continuation-in-part of my copending application Serial No. 742,673 filed April 19, 1947, now abandoned.

The principal object of this invention is to provide an improved heat exchanger which is extremely rapid and ecient in operation, which is simple and compact in construction, which is relatively inexpensive to manufacture, which may be readily disassembled for cleaning purposes, and which is particularly adaptable for use in the food industry for pasteurizing, sterilizing or cooling milk, fruit or vegetable juices or the like.

In this respect the heat exchanger comprises a substantially cylindrical hollow casing having an enclosed heat exchange chamber therein and having a smooth and slightly and uniformly tapered inner surface extending from end to end, and also a substantially cylindrical core longitudinally removably received in the casing, having an enclosed heat exchange chamber therein and having a slightly and uniformly tapered outer surface extending from end to end conforming to the taper of the inner surface of the casing to provide a tight seal between the casing and the core throughout their lengths when the core is received in the casing. A spiral groove is provided in the outer tapered surface of the core to form in conjunction with the casing a spiral passage through which the product to be heated or cooled is circulated.

A ring is removably and longitudinally adjustably carried by the casing and engages the end of the core for forcing the tapered outer surface of the core into sealing engagement with the tapered inner surface of the casing. When the ring is removed, the core may be longitudinally removed from the casing to expose the grooved external surface of the core and the smooth internal surface of the sleeve so that said surfaces may be readily cleaned.

The casing is preferably formed from two sleeve members or tubes which are secured together in spaced relation to form the enclosed heat exchange chamber therebetween, the inner sleeve member or tube having the smooth and slightly and uniformly tapered inner surface. The core also preferably includes an outer sleeve member or tube which provides the slightly and uniformly tapered outer surface on the core. The enclosed heat exchange chamber in the core may be formed by the outer sleeve member and end plugs cooperating therewith or by the outer sleeve member and an inner sleeve member or tube secured thereto in spaced relation.

Inlet and outlet ports communicate with the enclosed heat exchange chambers for circulating a heat exchange medium, such as steam, water or the like, therethrough. Inlet and outlet ports for the product to be heated or cooled extend through the casing and open into the tapered inner surface of the internal sleeve of the casing near opposite ends of the casing. These inlet and outlet ports register with the ends of the spiral groove in the tapered outer surface of the core to provide a straight through passage for the product to be heated or cooled. This eliminates pockets in which the product might be trapped and this is of great importance in the case of a heater, pasteurizer or sterilizer where the product would become overheated in such pockets.

Further objects of this invention reside in the details of construction of the heat exchanger and in the cooperative relationship between the component parts thereof.

Other objects and advantages of this invention will become apparent to those skilled in the art upon ref- 2,706,620 Patented Apr. 19, 1955 erence to the accompanying specification, claims and drawings, in which:

Fig. 1 is a side elevational view of one form of the heat exchanger;

Fig. 2 is a vertical sectional view of the heat exchanger of Fig. 1;

Fig. 3 is a vertical sectional view taken substantially along the line 3--3 of Fig. 2;

Fig. 4 is a sectional view of a support for the sleeve nerlriber or tubes forming the casing in the heat exchanger o 1g.

Fig. 5 is a sectional view of a secondary head utilized in the core of the heat exchanger of Fig. 1;

Fig. 6 is a sectional view of the outer sleeve member or tube of the core and the inner sleeve member or tube of the casing showing the slight tapered joint between these sleeve members;

Fig. 7 is an enlarged sectional view showing a modified form of the spiral groove in the outer surface of the core;

Fig. 8 is a diagrammatic view of an installation of heat exchangers in a milk storage and bottling system of a new type of dairying equipment;

Fig. 9 is atop plan view of a heater and cooler assembly utilizing two heat exchangers of a construction different from the heat exchangers illustrated in Figs. 1 to 7;

Fig. 10 is a side elevational View of the heater and cooler assembly of Fig. 1 showing the core of the cooler raised above the casing for cleaning purposes;

Fig. 1l is a vertical sectional view of the heater taken substantially along the line 11-11 of Fig. 10;

Fig. 12 is a vertical sectional view of the cooler taken substantially along the line 12-12 of Fig. 9;

Figs. 13 and 14 are diagrammatic top plan views of the heater and cooler of Figs. 11 and 12 illustrating the relative positions of the various inlet and outlet ports;

Fig. 15 is a horizontal sectional view taken substantially along the line 15-15 of Fig. l0; and

Fig. 16 is a side elevational view partly in section of a casing for a heater provided with thermal insulation.

Referring lirst to the forms of the invention illustrated in Figs. l to 8 there is disclosed a heat exchanger having a substantially cylindrical casing and a substantially cylindrical core longitudinally removably received in the casing. The casing includes an outer sleeve member or tube 1 and an inner sleeve member or tube 2. The inner surface 29 of the inner sleeve member or tube 2 is smooth and is slightly and uniformly tapered from end to end, the taper being of approximately 1.25% or less. The sleeve members 1 and 2 are secured together in spaced relation by heads or rings 4 and 5. The heads or rings 4 and 5 are provided with annular shoulders 38 and 39 for receiving the ends of the outer sleeve member 1, the sleeve member being secured to the heads or rings 4 and 5 as by welding, indicated at 22 and 23. The inner sleeve member 2 is secured to the heads or rings 4 and 5 as by welding, indicated at 24 and 26. There is thus provided between the sleeve members 1 and 2 an enclosed heat exchange chamber 12. The heat exchange iiuid in the form of steam, water or the like, enters the heat exchange chamber 12 through an inlet pipe 14, suitably secured in the outer sleeve member 1. The heat exchange iiuid is discharged from the heat exchange chamber 12 through an outlet pipe 15, also carried by the outer sleeve member 1. In this way heat exchange fluid is circulated through the heat exchange chamber 12.

The core includes an outer sleeve member or tube 3 having its outer surface slightly and uniformly tapered from end to end to conform to the taper of the inner surface of the sleeve member 2 of the casing to provide a tight seal between the casing and the core throughout their lengths when the core is received in the casing. One end of the sleeve member 3 is secured to a head or disc 37 as by welding, indicated at 2S. The other end of the sleeve member 3 engages a shoulder 40 of a head 7 and is suitably secured to the head 7, as by means of welding. The

heads

37 and 7, along with the sleeve member 3, form an enclosed heat exchange chamber 13 through which a heat exchange medium, such as steam, water or the like, is circulated. The outer surface of the sleeve member 3 of the core is provided with a spiral or helical groove 21, the convolutions of which are separated or divided by partition walls 36. When the core is received in the casing the spiral groove 21, in conjunction with the sleeve member 2, form a spiral passage through which the product to be heated or cooled flows.

The product to be heated or cooled enters the heat exchanger through an inlet pipe and discharges therefrom through an outlet pipe 11 after coursing the spiral passage 21. The inlet pipe 10 extends through the outer sleeve member 1 and through the inner sleeve member 2 to provide a port which opens into the tapered inner surface of the internal sleeve member 2 in registry with one end of the spiral groove 21. The pipe 10 may be threaded into inner sleeve member 2 and secured to the outer sleeve member 1 as by welding, indicated at 27. The outlet pipe 11 likewise extends through the outer sleeve member 1 and the inner sleeve member 2 and opens into the tapered inner surface of the internal sleeve member 2 in registry with the other end of the spiral groove 21. This outlet pipe 11 may also be screw-threadedly received in the internal sleeve member 2 and welded to the outer sleeve member 1, as indicated at 28.

A head 6 operates to pack or seal the joint between the casing and the core and in this respect, the head 6 is provided with a conical or tapered surface 30 for engaging a conical or tapered surface on the end of the inner sleeve member 2 of the casing. The head 6 has an annular flange lying adjacent the head or ring 4 and a ring or sleeve 8 is screw-threadedly carried at 32 by the head 4. When the ring or sleeve 8 is drawn up tight, the conical surface 30 of the head 6 engages the conical end of the tube 2 to pack or seal the joint between the casing and the core.

The head or ring 5 is provided with an internal flange 43 and an inner surface 44. Gaskets 31 are received by the inner surface 44 and abut the flange 43 of the head 5 and also abut the ange 41 of the head 7. A flanged sleeve 9 is screw-threadedly carried at 33 by the head 5, the ange of the sleeve engaging the head 7. As the anged sleeve 9 is tightened the core is forced into the casing and the gaskets 31 are compressed. In this way a tight seal is established between the two sleeve members 2 and 3 throughout their lengths and the end of the joint between the two sleeve members is packed against any possible leakage.

Heat exchange medium is supplied to the inner enclosed heat exchange chamber 13 by means of an inlet pipe 16 carried by the head or ring 5. This inlet pipe communicates through a port 19 in the heads 5 and 7 with a pipe 17 screw-threadedly carried by the head 7, as indicated at 35, and extending longitudinally into the heat exchange chamber 13. The inner end of the pipe 17 is open, as indicated at 34, so that heat exchange medium is supplied to one end of the heat exchange chamber 13. Heat exchange medium is discharged from the heat exchange chamber 13 by means of an outlet pipe 18, also carried by the head or ring 5. The outlet pipe 18 communicates through a port 20 in the heads 5 and 7 and a port 34 in the head 7 opening into the heat exchange chamber 13.

By removing the anged sleeve or ring 9 the core may be withdrawn from the casing to expose the inner smooth tapered surface of the casing and the outer grooved tapered surface of the core to facilitate cleaning of these surfaces. If desired, the head 6 may also be removed by removing the ring or sleeve 8, further to facilitate cleaning of the casing. To reassemble the heat exchanger the core is inserted into the casing and the anged sleeve or ring 9 is drawn up tight. When this is done a tight seal is established throughout the lengths of the core and sleeve and the ends of the joint between the core and sleeve are sealed. In order to register the ends of the spiral or helical groove 21 with the inlet and

outlet pipes

10 and 11 and to register the

ports

19 and 20 when the core is inserted into the casing, the ends of the casing and core may be provided with suitable spotting points. Should the seal between the core and the casing stick when the core is to be removed from the casing, then they may be quickly separated by circulating steam through the outer heat exchange chamber 12 and cold water through the inner heat exchange chamber 13. This will cause a differential expansion between the core and the casing readily to separate the joint between the casing and the core. In order to provide maximum turbulence in the product flowing through the helical or spiral groove, the center of the groove, as shown in Fig. 7, may be provided with an upstanding projection 32. Screw-threads 58 or the like may be formed on the outer surface of the inner tube 2 of the casing, as illustrated in Figs. 6 and 7, in order to increase the contact area between this tube and the heat exchange medium in the heat exchange chamber 12.

Heretofore in the production of heat exchangers it has been the custom to make the parts of cast metal. In accordance with this invention, however, I prefer to use standard dimension stainless steel tubing for forming the sleeve members 1, 2 and 3. The outer surface of the sleeve member 3 of the core, as shown in Fig. 6, is gradually decreased or tapered from end to end leaving the inside diameter at its standard dimension. Likewise, the inner sleeve member 2 of the casing retains its standard outside diameter but the inside diameter is tapered to correspond to the outside diameter of the core. This slight taper 29, of approximately 1.25% or less, permits the use of the standard dimension tubing and also insures continuous contact between the two engaging surfaces and avoids the possibility of leakage between adjacent convolutions of the helical or spiral groove 21 across the ridge or partition 36. While in Figs. l to 7 the heat exchanger has been shown in horizontal position, it may be positioned vertically with the right-hand end of Fig. 2 at the top.

While the heat exchanger, disclosed above, is of general utility, it has particular utility for pasteurizing, sterilizing or cooling food stuffs, such as milk, fruit or vegetable juices or the like, and may be advantageously utilized in the dairying system, diagrammatically illustrated in Fig. 8. This dairying system includes a vacuum receiving tank 45 in which milk that comes from milking machines is stored. The milk is drawn from the receiving tank 45 into a homogenizer 46 which also functions as a pump. The milk` 1s pumped into a pasteurizing unit 47 and then a holding tube or valve 48 and then passes a diversion valve 49 if the temperature of the milk at the exit of the holding tube 48 is up to 162 degrees F. lf the milk is not up to that temperature, it is diverted back through pipe 51 to the pasteurizing unit 47. However, if it is up to that temperature it passes the diversion valve 49 and enters a second unit 50 for water cooling the milk. It may also pass through a third unit 52 for cooling the milk to a lower temperature. The dairying system may also include a bottle lling machine having a vacuum tank 53 for receiving the milk to be bottled. The milk passes from the vacuum tank 53 under the control of a valve 54 for filling bottles 55 under vacuum. The capper 56 caps thebottles after lling and a revolving feeder may be utilized to maintain the vacuum in the chamber where the bottles are being lled and capped.

When the heat exchanger is utilized as the pasteurizer 47, steam or hot water may be utilized as the heat exchange medium. When the heat exchanger is used as the rst cooler 50, the heat exchange medium may be in the form of tap water and when the heat exchanger is. used as the second cooler 52, the heat exchange medium may be a refrigerating agent, such as sweet water, brine or the like.

In the pasteurization unit 47 the steam or hot water in the

heat exchange chambers

12 and 13 cooperates in producing the necessary heat for raising the temperature of the milk to 162 degrees F. In the installation illustrated in Fig. 8, the milk will not have been cooled after being drawn from the cows until it is pasteurized. Its temperature will be approximately degrees F. as the milk enters the pasteurizer 47. As a result, the milk will need to be raised only from 95 to 162 degrees F. instead of from 40 or 5() degrees F. to 162 degrees F., which would have been required if the milk had previously been cooled. When steam is used as the heating agent its pressure is controlled to the proper pasteurization temperature. In the event that water is used as the heating agent, its temperature is controlled by use of suitable thermostatic control and it may be circulated through the pasteurizer by means of pumps operating at the required pressure. This insures that the milk will be raised to the proper temperature. The rate at which the milk ows through the pasteurizing unit 47 under a pressure of 30 pounds per square inch is approximately 2.3 gallons per minute. With the rate of flow of milk controlled and the entering temperature of the milk substantially established and with the heating medium temperature and pressure under control, the end temperature of the milk may be very closely controlled in this type of enclosed pasteurizer. Since the milk is subjected to applied heat on all sides While it undergoes turbulence in its spiral flow around the core, all particles of the milk are acted upon and the highest efficiency is secured.

The heat exchange unit or cooler 50 is used to reduce the temperature of the pasteurized milk from 162 degrees F. to a point as near as possible to that of tap or well water. This water is circulated through the

heat exchange chambers

12 and 13 in a similar manner as the heating agent during pasteurization. The temperature of the milk at the outlet of this cooler unit 50 will be less than 10 degrees above the water that is being used for cooling purposes for the reason that the milk is acted upon on all sides by the cooling agent and has relatively great turbulence in its flow through the helical groove of small cross section area. The third unit or cooler 52 is used to lower the temperature of the milk to approximately 35 degrees F. before bottling. It may utilize as the cooling medium sweet water or brine which is cooled by any desired method of refrigeration and which is circulated through the

heat exchange chambers

12 and 13. If desired, the cooling may be accomplished by a direct expansion method of refrigeration, the refrigerating gases being circulated through the

heat exchange chambers

12 and 13. In any event, the refrigerating agent is circulated through the heat exchange chambers in substantially the same manner as the steam or hot water is circulated through the pasteurizing unit.

It is common in all high temperature pasteurization practices to hold pasteurization temperatures for short time periods. Health authorities require that in the high temperature short time pasteurization of milk, the temperature of the milk must be held at the 162 degree F. level for l seconds. Such short time periods are under the control of the diversion valve which will return any part of the milk that is not at the required temperature back to the initial pasteurizing unit. A self-recording thermometer may be used to indicate continuously the operating temperatures. These expedients shown diagrammatically in Fig. 8 cooperate with the heat exchangers of this invention to form a complete milk handling system.

Figs. 9 to 16 illustrate further forms of the heat exchanger` of this invention, which likewise are of general utility but which are particularly useful in processing food stuffs. In Figs. 9 and 10 there is disclosed a heater and cooler assembly including a heater generally designated at 110, a cooler generally designated at 111 and a supporting stand for the heater and cooler generally designated at 112. This heater and cooler assembly is particularly useful for pasteurizing or sterilizing milk, fruit or vegetable juices or the like, the heater 110 doing the pasteurizing or sterilizing and the cooler 111 doing the cooling.

The heater 110 is illustrated in more detail in Figs. 11 and 13. The heater includes a substantially cylindrical casing having an outer sleeve member or tube 114 which is secured, as by welding, to flanges 115 on an inner sleeve member or tube 116. The inner surface 117 of the inner sleeve member 116 is smooth and slightly and uniformly tapered from end to end. The wider portion of the tapered inner surface 117 is located uppermost. The flanges 115 space apart the outer and

inner sleeve members

114 and 116 to form therebetween an enclosed heat exchange chamber 118.

A fitting 119, having a hole 121 communicating with the enclosed heat exchange chamber 118, is secured, as by welding, to the outer sleeve member 114 near the top thereof for delivering steam, hot water or the like to the heat exchange chamber 118. Likewise, a fitting 120, having a hole 122 communicating with the heat exchange chamber 118, is secured, as by welding, to the outer sleeve member 114 near the bottom thereof for discharging steam or water from the heat exchange chamber 118. In this way heat exchange uid, such as steam or water, may be circulated through the heat exchange chamber 118 in the casing. A supporting ring 123 is secured to the bottom of the casing, as by welding, and, likewise, another ring 124 is similarly secured to the top of the casing. A fitting 125 is secured to the casing, as by welding, and it extends through the flange portion 115 of the casing and opens into the tapered inner surface 117 of the internal sleeve 116 near the bottom thereof. Another fitting 126, likewise, is secured to the casing and extends through the flange portion 115 and opens into the tapered inner surface 117 of the internal sleeve 116 near the top of the casing. The fittings and 126 form inlet and outlet ports for the product to be heated as, for example, the milk or juices to be pasteurized or sterilized.

The heater also includes a substantially cylindrical core which is longitudinally removably received in the casing. The core may be vertically inserted into the casing and vertically raised therefrom. The core includes an inner sleeve member or tube 128 which is provided at its ends with flanges 129 to which is secured, as by welding, an outer sleeve member or tube 130. The outer surface of the external sleeve member 130 of the core is slightly and uniformly tapered from end to end and conforms to the taper of the internal sleeve member 116 of the casing. When the core is inserted in the casing a tight seal is established between the two

sleeve members

116 and 130 throughout their lengths. The outer tapered surface of the sleeve member 130 is provided with a spiral groove 131, the ends of the spiral groove terminating at, and in registry with, the inlet and

outlet ports

125 and 126, respectively, when the core is received in the casing. This spiral groove 131, cooperating with the inner sleeve member 116 of the casing, forms a spiral passage for the product being heated. Since this spiral passage terminates at the inlet and

outlet ports

125 and 126, a straight through passage is provided which eliminates pockets in which the product might be trapped and over heated.

The fianges 129 space apart the inner and

outer sleeve members

128 and 130 of the core to provide therebetween an enclosed heat exchange chamber 132. A fitting 133 is secured, as by welding, to the inner sleeve 128`and is provided with a hole 134 for introducing a heat exchange medium, such as steam or hot water, into the heat exchange chamber 132, this fitting 133 being located near the top of the core. Another fitting 135 is secured, as by welding, to the inner sleeve 128 near the bottom thereof and it communicates with the heat exchange chamber 132 for discharging the heat exchange medium therefrom. The

fittings

133 and 135, therefore, provide means for circulating a heat exchange medium through the heat exchange chamber 132.

The

sleeve members

116 and 130 are relatively thin so that rapid and efficient heat exchange takes place between the

heat exchange chambers

118 and 132 and the spiral passage 131 located therebetween. The

heat exchange chambers

118 and 132 are completely isolated from each other and from the spiral passage 131 so that there is no danger of the heat exchange medium entering or leaking into the spiral passage containing the product being heated. Because of the tapered surfaces on the casing and the core throughout the length of the casing and the core, a tight seal is at all times maintained therebetween which substantially eliminates leakage of the product from one convolution of the groove 131 to the next convolution and forces the product to flow along the spiral passage. The outer sleeve member 130 of the core is provided with an annular groove 137 near each end thereof and an O-ring 138 of resilient material, such as neoprene or the like, is located in each of these annular grooves. These O-rings 138 cooperate with the tapered inner surface 117 of the casing for positively packing the ends of the two

sleeve members

116 and 139 Without in any way interfering with the tight seal between and throughout the lengths of these two sleeve members. In the unlikely event that leakage of the product should occur, the O-rings prevent the product from leaking from the heat exchanger. The O-rings provide self-adjusting sealing means for effectively preventing any leakage of the product being heated.

The casing of the heater 110 is vertically mounted on the supporting stand 112. In this connection, the ring 123 is secured by means of a spacer ring 140 and screws 142 to an upper platform 141 of the supporting frame. The platform ring 141 is carried by legs 143 to which is also secured a lower platform 144. The legs 143 may be formed of pipes or tubes, or the like, and secured, as by welding, to the upper platform ring 141 and the lower platform 144.

The lower platform 144 carries a motor, such as an hydraulic motor. The base 146 of the motor is secured to the platform 144 by means of screws 147 and it carries an upwardly extending cylinder 148. A piston carried by a piston rod 149 reciprocates in the cylinder 148. The upper end of the cylinder 148 is provided with a head 150 for guiding the piston rod 194. The upper end of the piston rod 149 is provided with a screwthreaded extension 151 on which is clamped a hub 152 of a spider by means of a nut 153. The legs 154 of the spider are secured, as by Welding, to the upper end of the inner sleeve member 128 of the core. When hydraulic pressure is applied to the motor the motor raises the core vertically from the casing, such vertical position being illustrated at the right of Fig. l0. When the hydraulic pressure is released, the core drops vertically into the casing. By reason of this vertical movement of the core, self-alignment between the core and the casing is assured without any tendency to cause the mating tapered surfaces to become out of round. When the core is thus raised out of the easing, the inner smooth tapered surface of the casing and the outer grooved tapered surface of the core are exposed so that they may be readily cleaned.

AThe cylinder head 150 is provided with a pin 156 to be received in a hole 157 in the hub 152 of the spider when the core is received in the casing. The pin and hole form interengaging locating means for fixing the rotative position of the core with respect to the casing for registering the ends of the spiral groove 131 With the inlet and

outlet ports

125 and 126. A ring 158 is removably and longitudinally adjustably carried by the casing by means of studs 159 secured in the ring 124 and cooperating nuts 160. When the core is received in the casing the ring 158 is applied over the studs 159 and the nuts 160 are then applied to the studs and are tightened to force the core into the casing so as to assure a tight seal between the tapered surfaces of the core and the casing. To elevate the core above the casing, the ring 158 is first removed and then hydraulic pressure is applied to the motor. When the core is so elevated, a pair of sector shaped braces 72, having holes 73, is applied to the upper end of the casing, the holes 173 accommodating the studs 159. These braces 172 are held in place on the studs 159 by the nuts 160 and the inner edges of the braces 172 engage the piston rod 149 for readily supporting the elevated core during cleaning operations. When it is desired to lower the core into the casing, of course, these braces are removed. The braces 172 are illustrated in Fig. l5 and are shown applied to the cooler 111 at the right side of Fig. 10.

The cooler 111 is illustrated in more detail in Figs. l2 and 14 and the construction of the cooler is substantially the same as that of the heater 110 and like reference characters have been utilized for like parts. The essential difference between the cooler 111 and the heater 110 is in the construction of the heat exchange charnbers. In this respect, the inner sleeve member 116 of the casing is provided exteriorly with a spiral rib 162 for forming a spiral heat exchange chamber 163. The upper end of this spiral heat exchange chamber 163 terminates at and communicates with a fitting 164 through which a cooling medium, such as water, may be introduced into the spiral heat exchange chamber. The lower end of the spiral heat exchange chamber 163 is provided with a fitting 165 for discharging the cooling medium.

The outer surface of the inner sleeve member 128 of the core is also provided with a spiral rib 171 for providing a spiral heat exchange passage 166. The upper end of the heat exchange passage 166 terminates in a fitting 167 for supplying a cooling medium to the heat exchange passage. Likewise, the lower end of the heat exchange passage 166 is provided with a fitting 168 for discharging the cooling medium from the spiral heat exchange passage 166. The product, such as milk, juices and the like, is fed into the spiral groove 131 by means of an upper fitting 169 and is discharged from the spiral groove 131 by means of a lower fitting 178. The

fittings

169 and 170 extend through the casing and open into the tapered inner surface of the internal sleeve 116 in registry with the ends of the spiral groove 131. The spiral groove 131 and the spiral

heat exchange passages

163 and 166 all run in the same direction and, as illustrated, they are shown to be in effect in the nature of right-hand threads. The

spiral passages

163 and 166 operate to prevent stratification of the cooling medium and thereby provide rapid and efficient heat transfer. The operation of the cooler, with the exception of the direction of heat transfer, is essentially the same as the operation of the heater.

The cooler 111 is vertically mounted on the supporting frame 112 in the same manner as the heater, The

vertical legs 143 of the supporting frame are connected together and braced by transverse braces 175 which also may be made of pipes, tubes and the like, suitably welded to the vertical legs. By mounting the heater and cooler on the common supporting frame they may be cooperatively associated to perform desired processes. For example, the heater may be a pasteurizer or sterilizer for pasteurizing or sterilizing milk and the cooler 111 may be utilized for cooling the pasteurized or sterilized milk. In this connection, the outlet fitting of the heater may be connected by a relatively large diameter pipe 176 to the inlet fitting 169 of the cooler, this connecting pipe 176 acting as a holding valve. The connecting pipe 176 is provided with a T fitting 177 having a thermometer well for receiving a temperature-responsive device connected to a suitable control instrument by a connection 178. The outlet fitting of the cooler may be connected by a pipe 179 to a diversion valve 180 operated by a motor 181. So long as the temperature of the pasteurized or sterilized milk passing the fitting 177 is maintained at the desired pasteurizing or sterilizing temperature, the thermometer controller operates the motor 181 and, hence, valve 180 to pass the cooled milk through pipe 182 to a suitable bottling or canning mechanism. If, on the other hand, the temperature of the milk at the T fitting 177 should decrease below the desired value, the motor 181 and valve 180 are operated to divert the cooled milk through pipe 183.

Fig. 16 illustrates a casing for a heater which is lagged with thermal insulating material. Here the heater casing is substantially the same as the heater casing of Fig. l1 and like reference characters have been utilized for like parts. In Fig. 16 the

rings

123 and 124 are made wider and a thermal insulating material 185 is packed about the outer tubular member 114 between the

rings

123 and 124 and a suitable outer shell 186 may be secured to the

rings

123 and 124 for maintaining the insulating material 185 in place. The use of this insulating material provides for greater efficiency in operation of the heater.

When the heat exchangers of this invention are utilized for heating or cooling food stuff, such as milk, fruit or vegetable juices or the like, the heaters and coolers are preferably made of non-corrosive metals, such as stainless steel or the like. This not only makes it possible adequately to clean and sterilize the heat exchangers, but it also provides a neat appearance. When the heat exchange assembly is utilized for pasteurizing or sterilizing milk, the milk may be forced through the heater and the cooler under pressure by the homogenizer. As a typical example of the use of the assembly for this purpose, the following dimensions have proven to be very satisfactory: The cores of the heater and cooler are substantially 20.250 inches long and have a diameter of substantially 12.250 inches at the large end and 11.898 inches at the small end. This provides a taper of substantially 1/2 degree. In the heater the spiral groove 131 is substantially 3%; inch wide and substantially '0716 inch deep and the spiral groove extends along the core for substantially 16.250 inches. The groove has 321/2 turns, which provides a 100 foot long groove through which milk passes at a velocity yof substantially 24 ft. per second. In the cooler the spiral groove 131 is substantially 3A inch wide and 1A inch deep and it extends along the core for substantially 17.062 inches. The spiral groove has 191/2 turns to provide a passage length of substantially 60 feet through which the milk passes at a velocity of 10 feet per second. Both the heater and the cooler have substantially the same rate of flow of milk therethrough, being about 250 gallons per hour. The milk may be rapidly heated to pasteurizing or sterilizing temperatures by the application of steam to the

heat exchange chambers

118 and 132 at normal pressures. Likewise, the milk may be rapidly cooled to suitable temperatures for bottling and canning by supplying water to the heat exchange chambers or

passages

163 and 166 at usual tap water temperatures.

Reference is made to copending application Serial No. 223,482, filed April 28, 1951, by Roy R. Graves and Edward K. Kuhles, having a disclosure corresponding to the disclosure of Figs. 9 to 16 of this application. The claims of this application are directed generally to the construction of the heat exchanger including the casing, core and clamping ring. The claims of the copending application include limitations to the O-rings, the locating means for angularly positioning the casing and core,

the supporting stand, and the motor means for raising the core vertically from the casing,

While for purposes of illustration several forms of this invention have been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure and, therefore, this invention is to be limited only by the scope of the appended claims.

I claim as my invention:

l. A separable heat exchanger comprising a substantially cylindrical casing including a casing member and a separate internal sleeve member secured adjacent its ends within the casing member and providing an en closed annular heat exchange chamber between the casing member and the internal sleeve member, the inner' surface of the internal sleeve member being smooth and slightly and uniformly tapered throughout from end to end, a substantially cylindrical core including an external sleeve member and means for providing an enclosed heat exchange chamber within the external sleeve member, the outer surface of the external sleeve mem` ber being slightly and uniformly tapered throughout from end to end and conforming to the taper of the internal sleeve member of the casing, said core being longitudinally removably received in the casing and the tapered surfaces of the internal sleeve member of the casing and of the external sleeve member of the core providing the sole means for supporting and seating the core within the casing and providing a tight seal therebetween throughout their entire lengths when the core is received and pressed into the casing, a uniform spiral groove in the outer tapered surface of the external sleeve member of the core having its ends terminating at points spaced inwardly from the ends of the tapered surface within the contines of the tapered surface and forming an enclosed continuous spiral passage between said points which is sealed throughout its length and which is in heat exchange relation with the enclosed heat exchange chambers in the casing and core when the core is received in and pressed into the casing, an enclosed inlet port adjacent one end of the heat exchanger conimunicating directly with one end of the spiral passage and an enclosed outlet port adjacent the other end of the heat exchanger communicating` directly with the other end of the spiral passage to provide pocketless, straight through and uninterrupted flow through the ports and spiral passage, and inlet and outlet ports adjacent the ends of the heat exchanger communicating with the enclosed heat exchange chambers.

2. A separable heat exchanger comprising a substantially cylindrical casing including a casing member and a separate internal sleeve member secured adjacent its ends within the casing member and providing an enclosed annular heat exchange chamber between the casing member and the internal sleeve member, the inner surface of the internal sleeve member being smooth and slightly and uniformly tapered throughout from end to end, a substantially cylindrical core including an external sleeve member and means for providing an enclosed heat exchange chamber within the external sleeve member, the outer surface of the external sleeve member being slightly and uniformly tapered throughout from end to end and conforming to the taper of the internal sleeve member of the casing, said core being longitudinally removably received in the casing and the tapered surfaces of the internal sleeve member of the casing and of the external sleeve member of the core providing the sole means for supporting and seating the core within the casing and providing a tight seal therebetween throughout their entire lengths when the core is received and pressed into the casing, a uniform spiral groove in the outer tapered surface of the external sleeve member of the core having its ends terminating at points spaced inwardly from the ends of the tapered surface within the connes of the tapered surface and forming an enclosed continuous spiral passage between said points which is sealed throughout its length and which is in heat exchange relation with the enclosed heat exchange chambers in the casing and core when the core is received in and pressed into the casing, an enclosed inlet port adjacent one end of the heat exchanger communicating directly with one end of the spiral passage and an 'enclosed outlet port adjacent the other end of the heat exchanger communicating directly with the other end of the spiral passage to provide pocketless, straight through and uninterrupted ow through the ports and spiral passage, and inlet and outlet ports adjacent the ends of the heat exchanger communicating with the enclosed heat exchange chambers, and a ring removably and longitudinally adjustably carried by the casing at the end thereof where the internal sleeve thereof has the largest internal diameter and engaging the corresponding end of the core for forcibly pressing the tapered outer surface of the external sleeve of the core into tight sealing engagement with the tapered inner surface of the internal sleeve of the casing throughout their lengths when the core is received in the casing.

References Cited in the ile of this patent UNITED STATES PATENTS 536,354 Kohl Mar. 26, 1895 1,046,298 Hurley Dec. 3, 1912 1,639,051 Munday Aug. 16, 1927 1,854,619 Mortensen Apr. 19, 1932 2,445,115 Hanrahan July 12, 1948 2,508,212 Ball May 16, 1950