US2165094A - Heat exchange device - Google Patents

Description

July 4, 1939. F. J. FETTE 2,165,094

HEAT EXCHANGE DEVICE fljmk .Felde July 4, 1939. F. .3, FETTE l 2,165,094

HEAT EXCHANGE DEVICE Filed Aug. 2.6, `1936 4-SheetsSheet 2 July 4, 1939. y F, J, FET-rE 2,165,094

HEAT EXCHANGE DEVICE Filed Aug. 26, 1936 4 Sheets-Sheet 3 y f 5mm Ema www F. J. FETTE HEAT EXCHANGE DEVICE lJul), 4, 1939.

Filed Aug. 426, 1936 4 Sheets-Sheet 4 gmc/mw,

' rank Bite l Patented July 4, 1939 UNITED STATES HEAT EXCHANGE DEVICE y Frank J. Fette, Tampa, Fla.

Application August 26, 1936, Serial No. 97,922

7 Claims.

heat-transfer units in which the surface to bev exposed to the liquid to'be treated may be formed from smooth, thin plates of stainless steelor other vnon-corrodible materials.

Other objects of the invention will appear in the description of the preferred embodiments of the invention illustrated in the drawings forming a part of this specification, in which Figure 1 is an elevation, with parts in section and-parts broken away, of an assembly for Ipasteurizing,

cooling, and chilling milk; Fig. 2 isa plan View of the deviceof Fig. 1; Fig. Sis a plan view of a" plate forming one surface of a unit; Fig. 4 is an elevation with parts in section of a device for carbonating beverages; Fig. 5 is a transverse section on an enlarged scale of the elements in a single tank of the structure of Fig. 1; Fig. 6 is a similar transverse section of a modification of the sameelements; Fig. 7 is a longitudinal view with portions in elevation and portions in section of a modification in which the assembly of units is completely enclosed; and Fig. 8 is a transverse section in two different planes, on an enlarged scale, of the device of Fig. 7.

Itfis'to be understood that the details of conform a continuous channel for a liquid to be' treated,'which flows in a thin layer through a at broad passage between the confronting flat surfacesof thin sheet metal plates, the outer surfaces of the platescforming the wall of a. pas-` sage on each side of eachchannel, for a liquidwhich is maintained at a temperature higher or lower than that of thel'liquid to be treated.

Each unit consists of two plates I', each plate having a continuous' recess 2 pressed therein substantially parallel with its edges to receive a gasket 3 which maybe made of rubber or other suitable material. Near each end.. each plate is provided with one or more perforations or passages 4. In Fig. 3, two circular perforations are shown asspaced apart symmetrically, the metal surrounding each vof the perforations being l5 struck up as a frusto-conical projection 5. These projections being equally spaced from the central line of the plates and equally spaced from the end willregister with each other when the plates are placed back to back and will serve to l0 fix the distance between the plates. Transversely corrugated or wavy strips of metal 6 are arranged longitudinally and transversely of the plates I between the ribs Iformed by pressing the recess 2 into the metal and-these strips` 6 may be welded or soldered to the plates I. 'I'he meeting rims of the projections 5 will also be welded or solderedtogether to form a liquid-tight joint around the passages l. In apparatus in which 'the liquid is to be under considerable 20 pressure, an additional brace for the central portion of the plates may be provided by securing a wavy strip 8 longitudinally between the two plates of each unit, as indicated in Fig. 5, this strip being omitted in Figs. 1 and 4. 25

The end pieces 9 are preferably of cast metal such as aluminum, or ofone of the light alloys, each member having one surface iiat and formed with a recess I0 corresponding in size and position with that of the recess 2 in the plate which 30 will confront it when the units are assembled. Near-one end, each end piece has a recess I.I of considerable transverse extent. The opposite surface of each member 9 is formed with strengthening ribs 'I2 and with a hollow boss I3 35 to receive an inlet tube I4 or an outlet tube Il', as the member 9 maybe used at one end or the other of the series of plate units. In Fig. 5, the 4boss I3 for the inlet tube Il is at the top, and

it has secured therein a stuiling box fitting I5 4o externally threaded at I6 to receive a gland I1 having a central cylindrical portion I8 adapted lto bear `upon packing I9 within a. recess in the fitting I5 surrounding the tube Il.y The bottom 'end piece has a short length tube Il' secured v45 within the boss I3 to project an .inch or sov out of the boss, the amountof projection being suficient to bring the outer end of the tube Il' about midway of the length of arubber tube 2l held within a recess in a anged tting 2l se- 50 cured upon the-bottom of a tank 22. The ex' terior of the fitting 2I is threaded tor'eceive a hollow nut 23 which bears upon a gland 24 tocompress the tube 20 upon the ends ofthe metal- 'tubes Il and I4',

as will be' explained herein- 55 the gasket 3 with the passage or passages 4 at the end of the member 9 remote from the recess The upper surface of this unit will have a recess 2 in 'which another gasket 3 will be placed,

to receive a second unit of two plates which will be set with its passage or passages 4 at the'same end as the recess and remote from the passage or passages 4 of the first unit. This'procedure will vbe'continued with thev passages alternating between the two ends until a suiicient number .of units have been' used to provide the desired length of channel, whereupon the top end piece 9 will be set upon the gasket of the top unitwith its recess remote from the passage 4 of the uppermost unit. When an odd number of units is used, as for example,` the three units used in the assembly illustrated in Fig. 5the inlet and outlet tubes will be at the same endl of the assembly as clearly shown in Fig. 1, but when the units are even in number, as shown in Figs. 4 and 7, the inlet tube will be atone end and the outlet tube at the other end.

Liquid entering through the tube I4 'atthe top in Fig. 5 and'passing through the bore 25 will encounter a solid plate I opposite the recess and will flow in a thin sheet through the narrow space between the end piece and the top plate until it reaches the passage 4 at the other end.

'Opposite the passage 4, the solid plate I of the next lower unit-will cause the liquid to, flow through the space between the units ,until 'it reachesthe next passage 4 at the remote end, and so on to the lowermost unit, where the lower end piece 9 directs the flow to the recess |I and through the bore to the outlet tube I4'. The space between the confronting surfaces of the plates of two adjacent units is determined by the thickness of the gaskets 3 and such, gaskets may of course be made of different thicknesses to prol receive sections 21 of larger pipes, which may be secured to the pipes 26 by setscrews 28. The

. sections 21 are connected in pairs by transversely arranged angle iron brackets 29 which may be welded'to the sections 21 onl opposite sides there- -of to form ilat supporting surfaces for the tanks 22, 36, 'and 3|.

- In each tank, an assembly of plate units and end plecesis set with the outlet tube I4 in the fitting 2| and with the central portion of the lower end piece directly above the brackets 29. A clam screw `32 operating in a nut 33 held centrally Within oppositely extending arms 34 bears vwithin a recess 35 in the upper surface of the.

rib I2.' The outer ends ofthe arms 34 are formed as hooks to engage-the pipes-26 beneath the sec-` tions 21, so that when the screw is turned by the handle 36, the sections 21 will resist upward movement of the arms andV thescrew will act to force the top end piece 9 down upon the units underneath, compressing all of the gaskets 3 and holding the assembly securely in place in the tank. A rubber gasket 31 surrounding the tube I4 beneath the boss I3 serves as aY water seal as well as assisting in supporting the boss upon the floor of the tank. Legs 38 at the corners of the low'er end member .may be used to prevent tilting of the assembly.

While the assemblies are being placed within thetanks, they may be held together by any temporary clamping means and the tubes I4 and I4 will be free to be slid within the stufling boxes before the glands and nuts are tightened to clamp the packing on the tubes. the tanks will be suiiicient -to permitthe removal -and replacement of the plate assemblies without disturbing the position oi the tanks or of their supporting brackets.

Each tank is arranged for the circulation of a liquid therethrough entering through the inlet pipes 39, passingthrough the plate units between the plates I through the spaces provided bythe corrugated strips 6 and-out at the other side of the tank through outlet pipes .40 preferably of` The space between I Since the arrangement shown in Fig. 1 is primarily meant for use in pasteurization of milk, the tank 22 is supplied with water'heated 'to a temperature slightly above 142 by an electric heater .unit 43 mounted within a small tank 44 and controlled by a thermostat 45 `having its plug securedwlthin the T 46 in the outflow side' of the.' circuit, and a'pump 41 acting to force the heated water through the pipe 48 to the inlet pipes 39 of the tank.

The lowermost tank, 3|, is arranged to be supplied with a brine maintained at a temperature just above freezing in avrefrigerator (not shown) from which the pipe 49 leads to the pump 50 which forces the brine through pipe 5| to the inlet pipes 39' of the tank 3|, the overflow pipe 52 returning the brine tothe refrigeratlng means for further cooling. Both circulating pumpsmay be driven' by a common motor 53.

Milk entering the tube I4, preferably from a suitable strainer, (not shownin Fig. 1 but ,findicated at 9| in Fig. 7), will flow by the pressure of gravity back and forth through the thin spaces between the exterior surfaces of the units, receiving heat, from the heated water flowing through the units, and since this heat is always kept below the boilingpoint, there is no possibility of the milk being cooked at any point during its ow through the pasteurizing assembly. The rate of ow will be regulated to make the time of treatment as long as may be necessary. The-number of units may be increased at will for greater capacity of the assembly without other changes in the system. A H

From the pasteurizingv tank, the milk will flow down into the assemblyin the cooling tank 30 to be reduced in temperature from |42 to that of the water system, andfrom the tank.3||. the

cooled will flow into the assembly the bottom tank 3l, where the'brine may bemade to chill it to as low a temperature as is desirable.

While the valve l which regulates the flow of the milk is shown las discharging into the open -top'of a milk can 5 5, it will be evident that it may lead to a bottling device of any suitable kind, so that the milklwill not be exposed to the air from the time it is strained until it enters the bottles or the storage can or tank.

y It may here be 'remarked that the ordinary cooler formilk at present incommon use, in which milk ows'from a strainer over a series of cooling pipes exposed to the air of a dairy, serves to add to the vstrained milk during the cooling process all of the moisture condensed from the surrounding air, together with bacteria, fungi, and perhaps also insects that may be in the air, whereas the present device serves to exclude all air and protects the milk during the whole process of heating and cooling and chilling.

I'he modification shown in Fig. 4 is intendedfor use in carbonating beverages, the apparatus being arranged to introduce the gas into cold liquid under pressure while maintaining a temperature as low as is permitted short of freezing. The assembly illustrated has six plate units,'which may be exactly the same in construction as those shown on a large scale in Fig. 5. In view of the fact that the liquids used for carbonating are not subject to rapid deterioration and that daily cleaning of the plates is not necessary, the connections may be made less readily removable than in the apparatus just described for use with milk. The end pieces 9 are shown as clamped upon the intermediate units by two clamp hoops 56, one

near each end, andeach having a clamp screw 32 with a handle 36. The clamps will be put in place on the assembly before it is inserted into the tank and no further clamping means will be required to hold it inthe tank.

A tube 51 screws into theboss I3 and is centrallythreaded to receive a lock nut 58 inside 7 the tank 59 and a lock-nut 60 outside of the tank,

with a rubber gasket or 'washer forming a water seal between the tube and the tank. Upon the lower end of the tube 51 is screwed a valve fitting 6I having a nozzle 62 regulated by a needle 63.

4Below thenozzle is an inlet to receive a tube 34 connected with any suitable source of carbon dioxide under pressure, and above the nozzle 62 is an inlet for a cold liquid to be carbonated, supplied by a pipe 65 leading from a suitable container. Neither the containerfor-'the liquid nor the carbon dioxide gas tank is illustrated since perature as low as necessary to obtain the desired degree of carbonation. By arranging the gas to enter the previously cooled andpartially carbonated liquid at the point-of entry into the apparatus wherein the gas and liquid are forced to flow a considerable distance while constantly being cooled close 'to the freezing point, the maximum degree of carbonation will be reached for the pressures employed.

In the devices Ashown in Figs. 1, 4, and 5, the end pieces 9 form one wall of the channel forV the liquid both at the intake and at the outlet end. When the end pieces'are of cast aluminum 3 or of certain light metal alloysg'the liquid treated or theliquid forced through for cleansing the system may adversely affect the exposed metallic surface, and even wheny there is noA such trouble because of the liquid, the rough exterior left by the. casting process will usually require machining to provide a smooth surface suitable for cleaning. The modification shown in Fig. 6 provides a separate -sheet metal end plate 61 having a funnel-shaped inlet or outlet portion 68 which extends through the cast end member 69 intoa rubber tube 29 held-within the boss I3 having a fitting I5, a gland 24, and a hollow nut 23, all of which may be. identical in construction and function with the parts similarly numbered in Fig. 5.

vIn this modmcationfftne1iquid \does not come into contact with the cast metal of the end piece 69 which serves merely as a backing for the sheet metal plate 61 and as a clamping member for the assembly -of pairs of plates I connected by passages 4 .and wavy strips 6 as in the original form. The gaskets 10 in this modification are shown as moulded i'n a diamond shaped cross section and as having thin lateral flanges or fins extending between the plates and acting as a means for determining the space by which the plate surfaces. shall be separated when assembled, and thus regulating the thickness of the flowing film or sheet ofliquid.

Instead of providing a separatesheet metal tank to receive the heat-transfer assembly, the end members may be modified to form a closed -chamber through which c ooling or heating liquid may be forced more rapidly under greater pressure. .Such a modification is illustrated in Figs. '7 and 8 in a'form intended for pasteurizing milk.

The lower end member may consist of a rell atively fiat cast plate 12 provided with a plurality of locking bolts 13 pivoted on lugs 14 and having -wing nuts 15 for engagement with the tops of spaced lugs 16 formed upon the outer surface of the top end member 11 which is made in the :form of a chamber of sumcient size to hold a plurality of sheet metal plate units 18 which may be identical with those'previously shown and described in the other embodiments of the invention, but are illustrated in a slightly different form. As in the modification shownin Fig. 6, separate sheet metal plates 19 are used at both the top and bottom to prevent the liquid from .coming into contact with the end members 12 or 11, these plates 19 having funnel-shaped inlet or outlet passages 80, 80' extending intov rubber f tubes .29 held in bosses I3 which have the same fittings and nuts asin the other types.

Ribs 8| extend longitudinally .of the end members in the direction of ow to support the end plates 19 and to provide channels 82 between the ribs for the heating or cooling uid. vThe gasvkets 33 between the plate units are shown as having iiat sides with rounded ends provided with .ns 84 similar tofthe fins 1I of the gaskets 10 of Fig. 6. Instead of corrugated strips as in the other forms, the longitudinal members between the plate ribs at the sides wherel a flow of liquid is not desired may be ,of an oblong tubular form as shown at 85. while the transverse strips '86 kwhich separate the ends of the plates of each unit may be of zigzag or chevroned form tofpernit passage of liquid.-

The heating or cooling liquid enters" the base through a pipe 81v and leavesgat the'other end yat the top of a tube 33 which leads to theV dis- 'harge pipe 39 secured in the base at the end u remote from the pipe 81, neither pipe interfering in any way with the, removal or replacement of the top member 11.

The vertical plane of section for the portion to the left of thev broken line in Fig. 8 passes through the inlet tube 80, and the plane .of section forftheportion at" the right of the broken` line is to the right of the outlet 4 tube in Fig. 7, with the ribs 91,/ the ends of the units, and the tube 88 all seen in elevation, with the top of the member TI partly broken laway. -The scale of Fig. 8 is one and a half times that of Fig. 7.

A gasket 90 in a channel around the periphery of the end member 12 receives the edge of the side walls of the member Tl and the locking bolts 13 draw the member 'l1 toward the member 12 to cause compression of all the gaskets to hold the entire assembly liquid-tight.

When this formof device is used for p asteurizingvmilk, a strainer 9| supported above the upper assembly is connected by a tube 92 with the inlet passage 80 at the top of member-11 so that milk may ow back and forth through this pasteurizing assembly and out at the bottom passagell' in member 12, whence a tube 93 leads it into the top-of the cooling assembly beneath. This cooling assembly 94 maybe a duplicateof the pasteurizing assembly and may be followed by a still lower chilling assembly as shown in Fig. 1. There will, of course, be automatic devices for heating the water in the pasteurizing assembly and for circulating the chilling brine, .but since these are fullysuggested in Fig. 1, they have lbeen left the recess by a passage for liquid.

2. A h e'at exchange-apparatusin which a plurality of unitsconstructed as in claim 1 are assembledfin a series with gaskets within the recesses separating the units to provide a continuous 'channel through the assembly, and end membersclamped upon the assembly of units to hold them in assembled relation, one of said end members being formed to surround the end and sides of the assembly and cooperating with l'the other 'end member to form a closed chamber fo the passageof a heat exchange liquid.

3. A heat'exchange unit comprising a pair of sheet metal plates each having a peripheral rib embossed on one surface and forming a corresponding recess on the other surface and each having at one end inward from the rib a portion struck upward toward the side with the rib and connected with the corresponding struck up por-A tion of the other Aplate of the pair to form a passage' for a liquid, and-meansv interposed be' l' tween the lribs and connected therewith to hold the plates together.

4. A heat exchange unitl comprising a pair of sheet metalplates each having a rib embossed on one surface near the periphery and forming a recess to receive a gasket on the other surface, wavy metal strips between the ribs and secured thereto at theircontact points to hold them together and to lprovide spaces for liquid, and a liquid-tightconnection between the plates forming a passage for a liquid.

5. A device in which a plurality of units constructed -as in claim 4 are assembled in a series with gaskets tted within the recesses to form a continuous liquid passage through the series.`

and end members clamped upon the ends of the series to hold the units in assembled relation, said end members being provided with inlet and outlet ports for liquid communicating with the liquid passage through the series.

6. A heat exchange apparatus comprising a plurality of sheet metal plates each having a shallow depression adjacent to the periphery'of the plate to receive a gasket, gasketsy mounted within the depressions and having a thickness greater than twice the depth of the depression whereby to separate the plates to form a thin passage between confronting surfaces of two plates when assembled opposite each other with the gasket in the depressions, and means connecting the two vplates between gaskets in pairs, back to back, one of the connecting means for each pair of plates providing a passage for a liquid, and end members clamped upon the units to hold them in assembled relation, said end members being provided with inlet and outlet ports for liqquidcommunicating with the liquid. passage Y formed by theplatesl and gaskets.

7. In a pasteurizena plurality of similar superposed `assemblies each comprising a plurality of heat transfer'units connected to form a conpasteurized, the uppermost assembly being provided withl means for constant supply of heated liquid and with meansfor automatically maintaining the temperature of the heated liquid within a limited range above the point of pasteurization. and below the boiling point, a lower assembly provided with means for a constant supply of a coolir'igliquid, and a still lower assembly provided with means for a constant supply of a refrigerant liquid, whereby a liquid to be pasteurized may descend by gravity through a heat transfer means adapted to raise its temperature to the pasteurizing pointbut below an injurious temperature, thence through a. heat transfer `means adapted to remove a great part of thev heat, and thence through a final assembly adapted to chill the pasteurized liquid to a desired low temperature.

FRANK J. FE'I'I'E.

' tinuous channel for the ilow of a liquid to bev

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