US1987182A - Heat exchanger - Google Patents

Description

Jan. 8, 1935. G. DLEN E1' AL 1,987,182

' HEAT E'XGHANGER med Mayu. 1932 ..g'swnms-sheet 1 mvEN'roRs wfg@ BY #eff-A oRNEY I JUL 3, 1935 G, DALEN ET Ax. 1,987,182

HEAT EXCHANGE'R Filed May 24, 1952 3 Sheets-Shea?I 2 INVENTQRS l Jan. 8, 1935. G, DALN Er Al.

HEAT EXCHANGER Filed May 24, 1932 3 Sheets-Sheet 5 INVENToRs BY de #e/rATToRNEY Patented Jan. 8, 1935 l UNITED STATESg PATENT ori-ics HEAT EXCHANGEB Gusta! Daln and Gustaf Erik Bjrklund, Lidingo, weden, assigner-s `to Svenska bolaget asaccumulator, Stockholm, Sweden, a corporation of Sweden Application May zi', 19:2, serial No. 613,230 In Sweden September 25, 1931 18 Claims. (CL 122-43) The present invention relates to heat exchange of circulation and of heat transmission in a c osed and has particular reference to heat exchange circuit for heat transferring fluid; to provide, in lsystems wherein heat is transferred indirectly a domestic hot water supply system, indirect heatfrom a source of heat to the body to be heated ing means in which the flow of heatytransmitting through the medium of heat transmitting fluid fluid is automatically governed within the path 5 circulating in a closed path in which it is vaof flow of the fluid in accordance with the rate porized at the source of heat and condensed by of condensationdue to the momentary requiredelivering 'heat to the body to be heated. y ments of the domestic supply to be heated; to

More particularly, the invention relates to improvide an indirect heating system in which va- 1o proved method and means for governing the rate por is generated in a relatively even manner and 1o at which heat is transferred by the circulating at a rate not exceeding the requirements of the fluid in accordance with the momentary heat resystem; and to provide an indirect heating sysquirements of the body to be heated. y tem of the character described in which auto- The invention is particularly useful for the matic regulation of the rate of vapor generation :5 purpose of heating a, supply .of hot water for doand of heat transfer through the system is ef- 15 mestic purposes with heat derived from a confected by a restriction in the path of circulation tinuously fired domestic cooking stove of the heat of the heat transferring medium. Other objects accumulating type, such as is disclosed in U. S. of the invention will appear in thedesoription to Patent No. 1,559,162 granted October 27, 1925 on "follow,

the application of Gustaf Dalen, but it is to be For purposes of illustrating the invention, we 20 understood that the invention is applicable in have shown in the accompanying drawings a other elds in which the body to be heated may number of forms of apparatus of the type designed be fluids other than water, or solids, and the to provide a supply of hot water for domestic source of heat may be of anyfsuitable character. uses, such supply being heated from 'a domestic In domestic water `heating installations of the stove of the accumulating type disclosed in the y2,15 above mentioned character, water is advantapatent above referred to.k Itis to be understood, geously used as the circulating heat transmitting however, that the apparatus shown in the drawfiuid but other uids may be employed, particuings is illustrative only and that the invention is larly in cases where the temperature level of the not to be limited to the general type of apparatus body to be heated is such that a fluid having a disclosed but may equally well be utilized in other` 30 vaporizing temperature above or below the vaporforms of apparatus employed for other purposes. L izing temperature of water is suitable. In the drawings:

Among the several objects of the invention are: Fig. l is a more or less diagrammatic vertical to provide indirect heating apparatus in which a section of va .domestic water heating apparatusr ,f heat transferring .fluid isfcirculated and alterembodying theV invention;v

l 35 nately vaporized and condensed in a closed path Fig. 1a is aview on an enlarged scale of part of of circulation and is permitted to have substanthe apparatus shown in Fis. l; tially unrestricted opportunity to expand upon Fig. 2 is a view similar to Fig. 1 showing anvaporization of a portionl of the fluid; to provide other type of the apparatus:

40 indirect heating apparatus of the characterre- Fig. 3 is a view showing schematically another 40 ferred to in which a closed circuit for circulation form of apparatus of the illustrated in Fig. 1; of heat transferring fluid is connected at a point Fig. 4 is a view, on a larger scale, showing part in the circuit where the uid is in liquid form to of stili another type of apparatus. an expansion line adapted toy contain a variable Referring now to Fig. 1 of thedrawings, referquantity 0f fluid, dependinsgupon the k8.11101111' 0f ence numeral 10 indicates a `hot water storage 45 fluid forced from the circuit of circulation due to supply tank for a domestic or like supply, from` vaporization of uid therein, and to maintain a which hot water is withdrawn through pipe 11 static pressure of liquid head on said circuit; to and to which water is. supplied by pipe 12. Tank provide indirect heating apparatus for automatif' 10 is preferably covered by a layer of insulating cally raising the temperature of a body.. t'o:.`be material 13 to prevent undue loss of heat by radi- 50 heated to a desired temperature level andthereation.

after automatically maintaining such" body at a Situated within tank 10, preferably in the lower temperature level no't exceeding thedesired tem- 4portion thereof, is the pipe coil 14, from the upper perature; to provide, in anin'direct heating sysend of which the pipe 15 passes through a suittem, means .for .automatically governing the rate able closure 16 in the bottom of the tank and from 55 the lower end of which the pipe 17 passes through closure 16 to the exterior of the tank. From the highest point of pipe 15 the pipe V18 leads to the exterior of the tank, this pipe being provided with a shut-off valve 19 outside of the tank.

Pipes v15"and 17 are connected at their lower ends to the upper and lower ends, respectively, 'of a coil 20 surrounding the combustion chamber casing 21 of a cook stove of the accumulator type indicatedgenerally at 22. 'Ihis stove comprises an annular heat accumulating member 23,

the lower skirt portion 24 of which extends into an annular refractory ilre box 25 within vthe casing 21. Removable covers 26 and 27 permit'the introduction of solid fuel into the magazinespace 28 within the skirt 24 and the fuel is burned on a grate 29. Air is admitted through any suitable opening below grat`e\29,.and the combustion gases pass through the annular ilue space 30 to the stack or chimney indicated at 31.

As will be evident fromA the drawings, coils 14 and 20 andfpipes 15 and-17 constitute a-closed circuit designated generally by reference numeral 32. Coil 2 0 may be said to constitute a vapor generator andA coil 14to constitute a condenser for condensing vapor generated in coil 20. In this level indicated at,40.

circuit a trap adapted to be fllled with liquidy at all times is provided by the elbow 33 at the 'lower end of pipe 17, this elbow extending below the lowest partot the coil 20. Connected to the lowest point in the circuit 32 is the pipe 34 which at its lower end advantageously terminata in a depending loop or elbow 35 and at its upper end is connected to the lower portion of the receptacle 36. Receptacle 36 is advantageously above the highest level of the circuit 32 and may be in open communication with the atmosphere through a suitable vent 37. The receptacle 36 may con veniently be mounted on top of the tank 10 as illustrated. A restriction providing an oriilce 38 vof small diameter is preferably provided in the pipe 34.y f

Turning again to the circuit 32, a restriction 39 providing an nriiice of small diameter is provided in the circuit, this orifice lbeing advantageously located in the elbow 33 between coil20 and pipe 34.

The operation of the apparatus isas follows, it being assumed vthat the tank 10 is illled with water to be heated. v

'I'he circuit 3 2 is lled with water through the receptacle 36 and the pipe 34, the flow of water into the closed circuit from the lowest point thereof being permitted by opening valve 19 to vent the trapped air from the' highest point in the circuit through pipe 18. Preferably the system is illled until the water reaches a height such that the receptacle 36 is partially filled. as to the vIf, now, fuel is burned in the stove 22, heat is ansmitted to coil 20 by conduction and Vradiation from the adjacent parts providing the ilre space in the stove and steam is generated in this coil. 'I'he steam generated passes upwardly through pipe l5 from pipe 15 and coil 14. The water displaced by the generation of steam ows into pipe 34 and thus to the receptacle 36 which acts as an expansion tank. Due to the tal cross-sectional area of the receptacle 36, the water forced into this receptacle by expansion in the closed circuit does not materially alter the height of the water level 40 so that the variation in static pressure due to head of liquid on the system is substantially negligible and the system into` coil 14, displacing water.`

relatively large horizon-r.

can be considered for all practical purposes as operating under constant pressure.

The steam which passes to the coil 14 is condensed by delivering its heat'to the 'water in tank 10 and the condensate from coil 14 returns to the 5 lower end oi'- coil 20 through the return or drain pipe 17. Circulation of steam through the system is eilected due to the difference inthe weight of the column of water in pipe 17 and the weight of the column roi' steam in pipe ,15.

'I'he heat absorbing'area of the coil 20, which governs the rate of vaporization of water in the circuit and the area provided by coil 14 for the condensation of steam, may be calculated in accordanceI withv well known principles of heat l5 transmission so that the rate at which heat is supplied to the water in tank 10 and consequently the rate at which'a tank o! cold water can be brought to desired temperature, meets the re quirements of the` individual installation. 20

During periods when cold water is being heated in the tank 10, all of the steam generated in coil 20 should be condensed in the coil 14 so that there is a liquid column in pipe 17 for-the full height thereof. thereby providing the maximum 25 speed of heat transfer.

i As the temperature of the water in tank 10 rises, the rate of heat transfer through the walls of the pipe coil 14. decreases and the rate of steam condensation accordingly decreases. is higher than the rate of condensation in coil 14,

a certain amount of steam will pass through coil 14 without being condensed and as a result. the height of the liquid column in thevreturnI pipe'17 will be decreased. This will operate toreduce 35 the hydrostatic head eilecting circulation and will accordingly slowdown the rate oi' circulation. Thus the rate ofvaporization also will bevv decreased. It will be evident that variations in i the quantity of water in the closed circuit 32 will 40, produce variations in the amount of -water in receptacle 36 and will also produce reversals of'ilow in pipe 34.

Assuming that the condenser and generator are both steam illled, it is important to prevent un- 45 restricted ilow of a solid column or iet oi' water into the generator coils since if this were permitted, a considerable amount of water might flow into the generator in such a manner as to be ilashed into steam, thereby producing explosive 50 action ofv a nature causing violent surges and water hammer in the system. In order to minimize such surges, the small oriilce 38 is pro-- vided in pipe 3,4, this orifice acting as acheck and another small orifice 39 is provided for the 55 same eilect in pipe 17. g I "1 By connecting the expansion line into the elbow` n 33 at the lowest part of the closed circuit 32, it will be evident lthat expansion ofthe fluid in the closed circuit will operate to force water and not 00 steam from this circuit into the expansion line. It is one of the objects of the present invention to provide apparatus which will automatically raise the temperature of the water in tank 10 to a predetermined desired level-and thereafter maing5 tain the temperature of the water at a substant tially constant level. In a' domestic hot/water system this temperaturelevel is below the temperature of the stesmb'eing. condensed and in, theevent that water is not withdrawn from tank 70 10 for an extended period the amount of heat supplied to the water in this tank should just -coxnpensate for the radiation losses if the temperature of the water is to be kept from exceeding the predetermined deslred leve If the rate of vaporization in coil 20 am.

. I the pipe 15' and with a small orifice 44 aifording This control of temperature in the tank as above mentioned is effected according to the present invention by automatically 'altering the rate of circulation in the closed system 32 in accordance with the rate at which steam is condensed in the coil 14.

. Turning Vnow to Fig. 2, there is illustrated another form of apparatus, according to the invention. It has proved convenient toconnect the expansion pipe 34'pto pipe 1'1 at a point close to the tank 10. This arrangement, vamong other things, facilitates the removal of air from the circulating system. To eliminate the fear of getting vapor into the'expansion pipe the leon--V denser is formed in a special manner.' The steam generated in coil 20 is carried upwardly through a pipe 15' which terminates at its upper end in the upper portion of a condenser comprising a closed cylinder 40a. Cylinder 40a is divided by a diaphragm 41 into an upper chamber 42 and a lower chamber 43. Diaphragm 41 is provided restricted communication between the two chambers. To enable the circulating system 32 to be filled, pipe 18' is provided, this p ipe being in communication with the upper portion of chamber 42. Flow through this pipe is controlled by means of the valve 19 located outside of tank 10.

Cold water is admitted to tank through the inlet pipe 12' and hot water is withdrawn through the pipe 11. 1

The expansion receptacle 36' is connected to the return pipe 17' by the vpipe 34', but as will' be observed from the il'gure, pipe 34 is connected into the closed circuit 32 at a higher level than in the arrangement shown in Fig. 1 andthe restriction 39 is placed in the pipe l'I' below the point where pipes 17' and 34 join. The restriction 39' prevents too rapid flow of water to the generator from either the supply in the expansion line or the supply in the lower portion of the condenser.

The function of the diaphragm 41 and the orifice 44 is to prevent vapor from entering the expansion pipe 34'. This is accomplished by the throttling effect of orifice 44. It is a known fact that an oriilce transmits a weight of vapor, which isapproximately only .03 o f the weight of water, transmitted by the same orifice andat the same difference of pressure, assuming that the vapor has a temperature of 100 C. and substantially atmospheric pressure.

The vapor generated in generator 20 rises in displaces a certain amount of water in the chamber 42 of condenser 40.I If the water in tank 10 is relatively cold, rapid condensation takes place. The water level in chamber 42 is determined by the temperature of the water in tank 10 in such manner, that the rate of condensation of the upper part of chamber 42, above the water level, is enough tocondense the vapor from the generator 20. When the temperature of water in tank 10 increases, the rate of condensation decreases. The balance between generating and condensing is maintained by the water level in chamber 42 sinking. At a predetermined temperature of water in tank 10, the water level in chamber 42 reaches the diaphragm 4l, and if now the temperature of ywater in tank 10 furthermore increases, the water level tends to sink below the diaphragm 41. In this case the upper part of chamber 43 also will contain vapor, which has to pass through orifice 44. The throttling' effect of theoriflce 44 now takes place of circulation in the circuit 32 decreases thereby causing less vapor to pass from the generator to the condenser. In this way the heat transmission automatically slows down.

.The condensing eillciency of the lower chamber 43 of condenser 40a should be great enough to condense all vapor, passing through the orice 44, thereby preventing vapor from entering the pipe 34. l

Turning now to Fig. 3, there v`is illustrated schematically another arrangement, in which the expansion pipe 34 is connected to the return pipe 17 close to the condenser 14. To prevent the vapor from f entering the receptacle 36 another condenser 14a is arranged in the lower part of the expansion pipe 34. If any vapor should enter the pipe 34, it will be condensed in condenser 14a, giving up its heat to the'water in the tank 10.

Another feature of this arrangement is, that if air should have entered the system, for example by entrainment or absorption in the water inthe system, this air will collect incondenser 14, there mixing with vapor, and slowing down the rate of condensation. When tank 10 isv at high temcondenser 14 and so causes vapor mixed with air to enter the pipes 1'7 and 34. The vapor and the air` rise to condenser 14a, where the vapor condenses. The air continues `to rise through pipe 34 and leaves the system by way of receptacle 36.v Inthis way from time to time the air will automatically be expelled from the system, thus ensuring continuous heat transmission.

In the figure, 20 indicates the generator, connected to the vreturn pipe 17 and toA the steam pipe 15.

One orifice 38 is arranged in the expansion pipe 34 and another orifice '39 in the lowest part of return pipe 17. The function of these orifices is. the same as before mentioned in connection with Figs. 1 and 2.

Turning now to Fig. 4 there is illustrated on an enlarged scale a portion of an apparatus of preferred commercial form. In the arrangement shown in this figure, the condenser 14 is of the coil type illustrated in Fig. 1 and is located at the bottom of a tank 10a having an outlet pipe 11a and inlet pipe 12a. .f

Coil 14' is divided into upper. and lower portions 14b and 14c, respectively, and the portion of the steam supply pipe 15a. inside ofthe tank is preferably insulated spaced from this portion of pipe 15a to provide an insulating chamber 46 between the two pipes. This arrangement minimizes condensation of steam at a pointin the system such that the condensate will have to return through the upflow pipe 15a.

'Ihe two portions o the condenser 14h and 14c are joined through a restriction which' instead of being provided by one small orifice is provided by a plurality of orifices in series which, in the present form of the apparatus are held in position in the closure member 16a by means of the cap 48 and spring 49.

'The mpmeet pox-uen e: the condenser n ventedwhich flow may be be controlled by an external cock or a removable plug 51.

Betweenl the discharge end of the-coil forming by means ofa sleeve 45 the portion 14o of the condenser and the return line' 17a there is placed a second restriction 52 1 scribed. The restriction provided at 47 provides vwhen the rate of condensation is low, thesteam Y the desiredresistance to flow oi' steam at a point intermediate the ends oi' the condenser so that which does pass through the restriction 'is condensed in the lower portion I4c oi' 4the condenser. The restriction 52 provides" the necessary resistance to prevent unduly rapid dow of water to the generator so that hammering in the system due to rapid local generation ot steam in the generator .is avoided.

It has been found in practice that a satisfactory form of apparatusis one in which the difierential pressure or liquid head tending to maintain circulation in the syste'm is provided by a column (assuming water to be the liquid circulated) having a height of approximately .08 of a meter, and in which the restriction to iiow provided in the closed circuit is such that the restriction is capable oi' passing, under the existing pressure conditions, only a small fraction of the weight oi' steam as compared with the weight oi' water which it will pass. When the restriction takes the form of an orifice, an orifice of 0.6 of a millimeter has been found satisfactory in operation, an oriiice of this size being capable of passing, in the form of steam, only about 3% of the weightof fluid which it will pass in the form of water. Instead of one orifice with a very small opening, in Fig. 4 there is shownva series oi' 6 orifices with a diameter of 1.2 m/m. this series of orifices tendling to provide the same throttling effect as that provided by a single orifice of very much smaller diameter.

The expansion line may be open to atmosphere or not as desired and, obviously, this yexpansion line need not comprise a separate pipe and tank but may be formed by a pipe alone. provided the pipe has sufficient capacity to take care oi' the desired expansion.

If water is used as the heat transmitting medium, the liquid in the expansion line may advantageously be covered by a layer of some lighter liquid such as oil which will act to prevent evaporation of the water and will also act to prevent the absorption of air by the water. k

If the temperature to which it is desired to heat the body to be heated is greater than the Vaporizing temperature of the heat transferring fluid at about atmospheric pressure, the latter iiuid may be maintained under any desired pressure in order to raise itsr vaporizing temperature by connecting the. expansion line, which in this instance would be closed to the atmosphere, to any suitable source of fluid pressure. Variations in the pressure to which the heat transferring fluid is subjected may also be effected by varying the heightof the liquid column in the expansion line.

From the foregoing description, it will be evident that in accordance with the present invention automatic control of the rate of heat transi'er to the body to be heated is effected in response to variations in the temperature of the bodyto be heated by the direct influence of the heat ,ab..

sorbing capacity of the body to Ibe heated and .without the intermediary of auxiliary regulating mechanism, so that the apparatus provides the im-j prising a source of heat., a tank adapted to con-- tain a body to be heated, means providing a closed circuit for circulating a heat transferring fluid between said source and said tank, said means comprising'a vapor generator adjacent to said source, a condenser-in said tank, a conduit for conducting vapor from the generator tothe condenser and a return line for conducting condensed vapor from the condenser to the generator said `returnlixie having a restriction therein of less cross-sectional area than the minimum cross-sectional area of said vapor conducting conduit, and expansion means associated with said return line between said condenser and said restriction.

2. Apparatus oi' the character described `comprising a source of heat, a tank adapted to contain a body to be heated. means providing a closed circuit tor circulating a heat transferring fluid between said source and said tank, said means comprising a vapor generator adjacent to said source, a condenser in said tank, fa conduitior conducting vapor from the generator to the condenser and a return line `for conducting condensed -vapor from the condenser to the generator, and

an expansion line connected to said return line, said return line having a restriction therein between the generator and the connection Sto the expansion line providing a smaller cross-sectional area in said returnvline than anywhere in the vapor conducting conduit, and said expansion line having a restriction therein.

3. Apparatus of the character described comprising a source oi' heat, a tank adapted to contain a body to be heated,` means providing a closed circuit for circulating a heat transferring fluid between said source and said tank, said means comprising a vapor generator adjacent to said source, a condenser insaid tank, an upfiow.

anywhere in said upfiow conduit. and an expansion line'connected to they retiu'n line between the restriction and the condenser.

4. Apparatus of the character described comprising a stove of the type intended for continuous operation, a tank for heating water, means providing a closed'circuit for circulation oi' a heat transferring fluid, said means comprising a vapor generator arranged to be heated by said stove, a condenser located in said tank, an upflow conduit for conducting vapor from the generator tothe condenser, a return line for conducting condensed vapor from the condenser to the generator and an expansion line connected lto the return 1in'e,.|sai\d return line having a reduced crosssection of less area than the smallest cross-sectional area in said upiiow conduit and said expanf sion line being connected to the return line between the condenser and the place oi' reduced cross-sectional area. Y l

5. Apparatus of the character described comline providing` a smaller area of now in said return line than 25 means for maintaining a 55 parts, and an expansion line connected to prising means providing a closed circuit for circulation of a heat transferring fluid, said means comprising a vapor generator, a condenser, an upflow conduit for conducting vapor from the 5 generator to the condenser and a return line for conducting'condensate from the condenser to the generator, an expansion line connected to said return line, means for applying heat to said generator, means for maintaining a body to be heatl ed in heat transfer relation with said condenser, and a restriction in said return line between the generatorand the connection to the expansion line providing a smaller cross-section for iiow in said return line than anywhere in said upfiow 15 conduit for governing the rate ofV admission 0f liquid to said generator.

6. Apparatus of the character described comprising means providing a closed circuit for circulation of a heat transferring fluid, said means 20 comprising a vapor generator, a condenser, a conto the condenser and a return line for conductling condensate from the condenser tothe generator, means for applying heat to said generator,

body to be heated in heat transfer relation with said condenser, means in said circuit for automatically governing the rate of circulation of the heat transferring iiuid therethrough in response to variation in the rate 30 'of condensation of vapor in' said condenser, said last named means comprising arestriction located within the condenser so that only condensate passes therethrough when the rate of condensation in the condenser is relatively high and vapor 35 `and condensatepass therethrough when the rate of condensation in the condenser is relatively low and an expansion line connected to the returnline.

7. Apparatus of the character described com- 40 prising means providing a closed circuit for circulation of a heat transferring fluid, said means comprising a vapor generator, a condenser, -a

conduit for conductingvapor from the generator to the condenser and a return line for conducting 45 condensate from the condenser to the generator,

/ means for applying heat to said generator, means for maintaining a body to be heated in heat transfer relation with said condenser, means in said circuit for automatically governing the rate of 50 circulation of the heat transfer fluid therethrough in response to variation in the rate of condensation of vapor in said condenser, said means comprising 'a restriction in said circuit located so as to divide the space within the condenser into two the return line. 1

8. Apparatus of the character described ccmprising means providing a closed circuit for circulation of a heat transferring fluid, said means 60 comprising a vapor generator, a condenser, a conduit for conducting vapor from theA generator to the condenser and areturn line for conducting condensate from the condenser to the generator, means for applying heat to said, generator, means 65 for maintaining a body to be, heated in heat trans .-A .l in said" fer relation with said condenser, means circuit for automatically governing the rat of circulationA pf 'the Yheat transfer fluid there,

through in response to 70 condensationlof vapor in said condenser, said meanscomprising a restriction in said circuit lo`- cated so as to divide the space within the condenser into two parts, an expansion line connected to said return line, and a restriction in the return 75 line between .the expansion line and the generator.

vto the condenser and Vgenerator with the upper end variation in" vthe -viate of 9. Apparatus of the character described comprising means providing a closed circuit for circulation of a heat transferring fluid, said means comprising a vapor generator, a condenser, a conduit for conducting vapor from the generator a return line for conducting condensate from erator, means for applyingheatto said generator, means for maintaining a body to be heated in heat transfer relation with said condenser, means in said circuit for automatically governing the rate of circulation of heat-:transfer fluid therethrough in response .to variation in the rate of condensation of vapor in said condenser, said means comprising an oricel insaid return line adjacent to the outlet of said condenser, and an expansion line connected to the return line at a point between the condenser and the orifice.

10. Apparatus of thelcharacter described'comprising a source of heat, a tank adapted to conduit for conducting vapor from the generator 4 ti' bOdYf fluid t0 be hefted. means Providing a 'closedcircuit for a heat transferring fluid, said means comprising a vapor generator arranged to be heated by said source ofheat, a condenser comprisingv a pipe coil located in said tank, a conduit forv vapory connecting the upper portion of said return line connecting the lower end of said pipe coil to the lower portion of 'said generator and a restriction in said pipe coil intermediate its ends, and an expansion line connected to said return lin'e. Y y

- 1. Apparatus of the lcharacter described comprising a source of heat,-a tank adapted to contain a body of fluid to be heated, means providing a closed circuit for circulation of a heat transferring fluid, said means comprising a vapor generator arrangedA to receive heat from said source, a closed vessel in said tank, means having an orifice therein for dividing the interior of said vessel into an upper and a lower chamber, a conduit for conducting vapor from said generator to said upper chamber and a return line for conducting condensate from the lower chamber to the generator, and an expansion y connected to said return line. l

12. Apparatus of the character described comprising a source of heat, a tank adapted to contain a body of fluid to be heated, means providing a closegcircuit for circulation of a heat transferring fl d, said means comprising a vapor generator arranged to receive heat from said source, a closed vessel in said tank, ilow restricting means in said vessel, a conduit for conducting vapor from said generator to said vessel, a return line for conducting condensate from the lower portion of said vessel to said generator anda restriction in said return line of smaller cross,- sectional area than the minimum cross-sectional area of said vapor conducting conduit, and an expansion line connected to the return line between4 said last-mentioned restriction and said vessel.

\ 13. n'apparatus of thewhrractelr'dllcibled. 'a

closed circuit for circulation of-mreheat transferring iiuid comprising a condenser having a second portion from which condensate is withdrawn, and a connection between said portions comprising a number of holes in series for restricting ilow of vapor from said ilrst to said second portion.

14. In apparatus of the characterdescribed, a tank adapted to contain fluid to be heated, a condenser for heating iluid located in the lower of said pipe coil,a

the condenser to the gen- ,.rst portion to which vapor is admitted and a l I portion to the upper part `contain num to be heated'.

- cross-sectional area o! now `portion ot ksaid tank, said condenser comprisingv a pipe coil'dlvidcd'into an upper portion and a lower'portion, a conduit for conducting vapor of said upper portion. a conduit for conducting condensate from the lower oi' said lower portion and-aconneetion between said portions,'said connection being accessible from the vexterior a removable body forming a series o! intrictipns between said two' portions.

15. In apparatus-oi' thek described atanxadaptedtoeontamanumtobe heated: a removable closure in the lower portion ci tank, acondenser for iiuid lcli a pipe coil having its'endsconnected to'oneninga in'saidclosure, a vapor supply conduit connected to the openinz in the closure in communication withtheinlet endotsaidunperportionacondensate return line opening in said closure in communication with. the discharge end of said lower portion, a passage in saidclosure connecting the discharge end of the upper portionand the inlet end roi' the lower ,a plurality o! densers tor heatina .fluid located in said means to conduct vapor from said aenerator one of said condensers, a return line for conducting liquid from mother o! said con to the vapor aenerator.

means accessible from outside said tank. a re.- strietion in said return line providing a smaller in saidY return line than in said vapor conducting means, and exoi sindV tank and 'comprising` laid.

'said relation with a conduit4 pansion means to said betherein and said tank. 1 17'. Apparatusotthe character describedcomprising a sour-ceo! heat. a tank adapted'to cony.

tain a body to, be heated, a closed circuit for circulating a fluid between said source and tankpfsaid and means to relieve condenser. Y

18. Apparatus ofthe coin prising a source of heat, means adapwdtocontainaboiiytobeheatedxneana` cloaedcircuit iorcirculatingaheat y nuid and transferring heat between said and said first named meam, namedtuto means comprising a vaporlenera acen source. a condenser in heat transmitting conducting vaportromthelenerator-tothe condenserand densedvaporfromthecondemer tor, expansion means', an line connect-) areturnline'iorconductina conf area otsaidsvapor restriction being locat`v between means and the generator.

Gus'rsr' DALEN. ausrumm; 8.19m

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