US1920122A - Heat interchanging apparatus and process - Google Patents

Description

`Iuly 25, 1933. J. L. CHAVANNE HEAT INTERCHANGING APPARATUS AND PROCESS Filed Oct. 16. 1924 4 Sheets-Sheet l INVENTOR July 25, 1933. J, L CHA-VANNE 1,920,122

HEAT INTERCHANGING APPARATUS AND PROCESS Filed Oct. 16 1924 4 Sheets-Sheet lf2 l f Uff/fun f/ f, LV)

INVENTOR f @i July 25, 1933. J. L CHAVANNE y1,920,122

u HEAT INTERCHANGING AP-PARATUS AND PROCESS Filed'Oct. 16, 1924 4 Sheets-Sheet 3 IJuly 25, 1933. J. CHAVANNE HEAT INTERCHANGING APPARATUS AND PROCESS 4 Sheets-Sheet 4 Filed Oct. 16, 1924 latented July 25, 1933 PATENT OFFICE JEAN LOUIS CHAVANNE, F PARIS, FRANCE HEAT INTERCHANGIN G APPARATUS AND PROCESS Applcation led October 16, 1924, Serial No. 744,076, and in France March 19, 1924.

My invention has for its object a process for the exchange of heat between two flulds which are circulated continuously.

The process especially relates to the utili zation of the calories carried by the products of combustion, but it is undestood that the invention may also be applied to any process in which the calories are utilizable in the described manner.

It is known that the calorifical exchanges take place under three forms: by conduction, by convection and by radiation and that in a temperature exchanger the calories carried by the heating fluid are divided lnto: calories retained by the cooled fluid, calories transferred to the heated fluid and calories dispersed by the external radiation of the apparatus. The first and third groups constitute the losses of the apparatus.

My process permits the reduction of these losses, thanks to my heat exchange device which utilizes simultaneously the three methods of heat transmission. The process consists in having the heating fluid circulated between a refractory body and a facing wall (or partition) which is refractory, conductive and of high radiative power, and the cold fluid circulated between said wall and a second refractory body which is not only refractory but of high radiative power. f he heat of the heating fluid will be transmitted by convection to the refractory body and to the wall, and the heat of the refractory body will be transmitted by radiation u to the wall, while the heat received by the heated face Will be transmitted by conduction-through the wall-to the heating face thereof. Furthermore, the heat of the wall will be transmitted by convection to the cold fiuid by the said heating face and by radiation to the second refractory body, and the heat received by the second refractory body will be transmitted to the cold fluid by convection.

ln order to obtain the optimal value of rapidity of exchanges it is necessary that all of the bodies mentioned have a high power of emission; it is also necessary that the wall be highly conductive, very thin and tight. lt is then necessary that the distance between the two refractory bodies and the wall be small, and that the gases circulate at high speed, the exchange by convection be as effective as possible takin account of course of the loss of load w ich results therefrom.

In order to obtain a good exchange by convection it is necessary that the iiuid vein participate in this exchange throughout its whole thickness, since the gases have a slow conductive power. For that reason I circulate the gases in very thin layers (a few millimeters) and it is of interest for renewing the molecules in contact with the wall to create eddy effects by any suitable means.

The same modes of heat transmission occur in the simplified devices made according to the present process. Moreover, in a large apparatus embodying a casing having a plurality of pipes therein, the internal lining of the casing provided with outer insulating material will act as a heat radiating body or bodies towards the external row of the group of pipes.

The pipe surfaces are such that the heat 7 transmission resulting from convection is ncreased by eddying of the circulating fluids, whilst the heat absorbing power and heat radiating power are as high as possible. This fact is not negligible for the heating fluid owing to the amount of steam (or vapors) and carbon dioxide which .it carries with it.

To those skilled in the art it will be apparent that the inventive idea may be embodied in various forms of apparatus.

One form of such theoretical arrangement will be secured, for instance, by circulating the fluid to be heated in a pipe p rovided with an inner radiating core having a diameter slightly smaller than that of the pipe and providing around the pipe radiating, bodies leaving around said pipe only a narrow space in which the hot fluid is made to circulate. As a variation of the same scheme the hot Huid may be circulated inside the pipe and around its inner core, while the fluid to be heated is circulated between the pipe and the surroundin body. In certain cases the same heating e ect can 'feo secured by re lacing the pipe and its, e'of `small diameter or of. `a very flattened section.

inner'core by a tu l lThe .means of the invention, generally stated,th'erefore involve: i v v v1.---Separatin`g th fiuids from .each otheil by a thin'. partition wall and limiting onv each side, or to one vside'only, the spaces provided l for the passa e of one-or the two fluids by .preferably re ractory and highly radiating odies, for the purpose, of: g i,

(a) Increasing vthe surfaces enhancing heat transfer; 4

(b) Increasingthe total useful perimeter surface of heat exchange to as .great an ex- Y tent as possible compared with its sectional area; that` is to say securing narrow pas# sages for the fluids (c) Kee mg easil high the speed of circulation o each fluid.

2.-,Selecting said partition wall very thin and of material as heat conductive as possible under operative conditions.

3.-'C'rculating -one or zboth` lfluids at a speed Vabove its critical speed thus allowing the effect of convection in the thin fluid layer fluid.

' To 'those skilledin thefart it will .be aparent that the inventive idea involved may embodied in a variety of structures, some ofthem being shown .in the accompanying drawings and that various changes may be -reference being had to the appended claims `for that purpose. c

made in the `application of the same; but -it is to `be expressly understood that certain features ma be used without other features thereo and the drawings are for the purpose of illustration only and are not de Signed to define the limits of the invention,

Insaid'drawlngsz" n E p ,Figs.' 1 and2A are typical arrangementsfof flues for conducting y.both fluids;

. Figs. 3, v4 and 5- show ldifferent forms Which the fines 'for conducting the Huid tov4 sections taken on fthelines 3'-3` and 4-4 vof Figs.; 4 and 3,:respectively;

a Fig. ,6- is af centrallongitudinal section. of a `composite flue 'pipe designed accordingv to the l'nventionjand provided with 'an interior 5v5; refractory member; -4

Figs'. v7 and8 are'central longitudinal seclustrating ali-arrangement of theinterior of a. heating apparatus according'to therinven'- tion; y V Figs. 10 and 11 show respectively Vin'ver` .et tical and in horizontal section, a complete .up tothe fluid to be' heated.v

apparatus designed according to the'finvention;

. Figs. 12 Aan'dl are, respectively, vertical andliorizontal sections of a rotary heatex- -ticularly to Fig. 1, 4 and 5 are the refractory and radiating bodies limiting outwardly the lpassages provided for the two fluids, while 2 is'the thin platewall separating the said fluids. 1 is thepassage provided for the hot fluid and 3 the passage provided for the fluid tobe heated. These passages are made narrow; in-other words, the distances T1 and T3 are keptsmall in comparison with e the section areas measured b WT.1 and WTa.

Such a system insures an e cient transfer of heat. Sincev the artition wall 2 is thin and of material hlghlyheat conductive, the temperatureon its face v which is in contact with the fluid to .be heated is very near the ncreasing the length of-travel o feach temperature-onthe other face which is in contact with the hot or heating fluid, thereby' insuring excellent conditions for `heat`trans.

fer. Furthermore, the limiting radiating ` bodies 4 and 5 lhave an action particularly. .beneficial and increasing considerably the efii- -ciency ofthe system. In the first place, the

face of the refractory body 4, looking to ward the partition plate 2, offers to. the contact of the hot fluid a surface about equal to that of the plate 2; this means that the refractory body 4 has the effect of approximatell doublingthe surface of heat absorp- 1 tion rom'thehot fluid. The heat'absorbed y by saidrefractory body .4 will afterwards be given up by radiation to the dividing plate 2 and then ltransmitted to the fluid to be heated or, to the other refractory body-5 which will in 'its turn radiate said'heat and give it The refractory body 5 is therefore heated byradiation from lthe dividing plate v2 and afterwards transmits its stored heat to the heated is then heated b and the .refractory body 5. It is therefore 'apparent that the-refractory body 5, simi- -larlytofthe action of body4,'has the effect v`of approximately/doubling the surface ofl Y heattransmission to'the fiuid to. be heated. It is thus obvious that the scheme involves a very'high .'eiiiciencyof the system, .as comvpared'withY 1 that of an Yordinary'. recuperator 4 and 5 are actingmostlygby radiation; they .without-therefractory radiating b0dies f Y It maybe noted that `the refractory blocks shall therefore be made of material having as much as possible a high heat radiating power under operative conditions. They may, however, be made of material more or less heat conductive, in which case they will store a certain amount of heat with more or less rapidity. For example, blocks of material having low heat conductive properties will permit, all other'things being the same, yof the reduction of the length of time during which an apparatus must be subjected to a preliminary heating up before a continuous run is initiated.

Fig. 2 represents another typical form of the invention, in which the Huid to be heated is circulated c'inside a pipe 2 of small diameter or a pipe 2" of Hattened section, having preferably at the same time very thin and heat conductive walls, while the hot Huid is conducted between the aforesaid pipes and refractory bodies 4, 4b, in spaces 1a, 1b which are kept narrow.

The radiating bodies 4, 4b have obviously the same beneficial effect as that shown previously for block 4 of Fig. 1.

It may be observed at the same time that the Hue for the Huid to be heated, here provided under the form of a pipe, could as well be constituted of two Hat thin plates, as plate 2 of Fig. 1, limiting the space therefor from the passage or passages for the hot Huid.

lt is also obvious that the two Huids instead of being circulated in opposite directions could be conducted along the same direction, and that they could also be interchanged in their respective flues, without interfering with the beneficial effect of the refractory bodies as described.

The two preceding examples are typical illustrations of one of the basic features of the invention, that is, the use of two radiating bodies for limiting to a narrow space on each side of a dividing wall each one of the flues provided for the two fluids; or the use of two or more radiating bodies for limiting outwardly to narrow spaces the Hue provided for one of the fluids, while a dividing wall eneloses the other Huid in another narrow space.

All Hues or passages being of narrow cross section, the speed of circulation of each fluid can easily be maintained above its critical velocity, for the purpose already described. The critical speed of a Huid in a conduit or passage as herein used refers to that speed or velocity which is necessary to create eddying of the fluid during its travel within said conduit or passage whereby the film phenomenon, so deficient in heat transmission, is avoided.

ln many cases it has been found practical to conduct the Huid to be heated inside of Hues having the character of` pipes, such as illustrated in Figs. 3 to 8, while these Hues are surrounded by radiating bodies such as blocks 4 of Fig. 9 for example. I will dcscribe hereafter the character of said flucpipes; but as already pointed out, it is to he understood that they may as well serve to conduct the heating fluid, this being replaced around the 'Hue-pipes by the fluid to be heated.

Figs. 3 and 4 show flue-pipes with outside walls and inner bodies corrugated, transversely for the purpose of increasing the surfaces of heat exchange and also for the purpose of promoting eddies in one or both circulating Huids.

Fig. 5 shows a cross section of pipe-fines where the passages, also kept narrow, are

corrugated in the cross-section for the pur- I pose of increasing the surfaces of heat transmission.

Fig. 6 shows a composite Huc-pipe dcsigned according to the invention and having an interior refractory member 5a of such diameter as to leave an annular passage 3" of narrow cross-section between the tubular member 18 and the radiating body 5a, which annular passage is open at its upper end and also at its lower end.- Suspended in the lower wall of the collecting conduit 19 and surrounding the tubular member 18 is another tubular member 2 of which the inside diameter is such as to leave an annular passage 3a of narrow cross-section between said tubular members 2 and 18. These tubular members 2 and 18 are preferably very thin and highly heat conductive. The tubular member 2 is closed at its lower end as shown and the annular space 3a opens at its upper end into the conduit 19, so that the Huid to be heated is conducted as per the arrows 13 and finally collected in the conduit 19. This arrangement supposes a plurality of such heating elements all attached to a common collecting conduit 19.

Referring now to Figs. 7 and 8, the Huepipes are shown as shaped in coils preferably with thin and highly heat conductive walls, the Hue 2 of Fig. 7 being simply a round pipe of small diameter. The refractory and radiating bodies 4a and 4b to be used in connection with this flue-pipe are so spaced with relation thereto as to leave narrow passages 1 for the hot Huid, this arrangement being inspired by that of Fig. 2. lThe upper end of this coil is connected by any suitable or desirable joint 2l to the holding member 25.

Fig. 8 is in every way similar to the construction shown in Fig. 7, except that the Hue 2 has its opposite side walls very close to each other, so as to leave a narrow or restricted passage 3 for the Huid to be heated, thereby serving to bring more effectively all of the Huid layers passing therethrough into contact with the walls of the Hue. The arrangements of the spiral coils `for the fines have the particular ad! fvantage that they lend themselves to the .y contraction and expansionv resultln when the ot 1er end' from the application of'heat of the fines mustl be fastened to a second yholding member similar to 25.

Fig. 9, which is a vfragmentary crosssection constituting an enlargement 0f ythe arrangement employed in Fig. 11, illustrates a typical arrangement of the interior of a heating *apparatus` constructed with vpipelues 2 with inner refractory bodies 5` as already described. Intermediate blocks or masses of refractory and radiatingmaterial 4 are interposed between the Iiues '2 and are so shaped and arranged as to leave narrow annular spaces 1 and other spaces 73 for the circulation of the hot fluid. As will be seen in Figs. l10 and 11, the passages 73 are intended for 'the cross-circulation of the hot fluid. Should this hot, fluid be circulated parallel to the ues 2 only, said passages 73 could be eliminated.

Figs. 10 and 11 represent a complete apparatus designed according to the.. invention, for instance for the urpose of heating air. 26 is a chamber having walls composed of any suitable insulatin material, the nature of which may depen upon the tempera` ture to 'be obtained for the air, or that of the heating fluid. Said chamber is provided with two horizontal partitions 28 and 29, dividing the i, chamber 26 into y an u per chamber 30, a lower chambers 311'an an intermediate chamber '32.. ,The cold air to be heated is admittedf'to the lower chamber.

stance.

31 through' a conduit 33, while` theintermediate chamberis provided with a port 92' for theadmission of hot gases and an exit for said gases in .the form of conduit 49. The heating gases may be derived from any suitable source and may be 4furnished by- Within the intermediate chamber 432 andl surrounding the.V pipes 2 are vstaggered baffles 375,37", .37 andl"v so arranged as -to leave a circuitous path ,forthe1 hoty gases passing over the top of, the baffle plate 36 around the lpipes '.21to; the exit 49 y for .the waste gases, `all asf will be clearly apparent fromk the k; arrows 11.1* As",l already .-explained, 4 areintermediateblockso radiating material,.so arrangediasfto leave to the hotgases I restricted passagesl around the flue-pipes 2,

and crosswisepassages 73. `Thesefblocks '4 are arranged in all of that portion of the intermediate chamber between the partitions 28 and 29, the bathe plate 36 and the side walls of the chamber 26 that isnot occupied b the tubes 2, except that on the left-hand si e or inlet side, as shown in Fig. 11, someunoccupied spaces 38 are left to facilitate the entrance of the hot gases, and on the `righthand side of Fig. 11 similar spaces 39 are or may be provided to facilitate the passage of the hot gases from balile 37 to baiile 37? and so on. v

In the operation of the .apparatus the hot gas supply is obtained from the burner 34 and from there the hot gases ass upward over thebale 36, then follow t e circuitous route around the bale plates 37, 37b 37 and 37d, passing through the restricted passages 1 vand the other passagesv 73. By reason of the restricted form of passages 1, the hot` ases' may be passed therethrough at a hig their critical speed vandall of the gases will thus be enabled to come intimately in contact with the outer walls of the pipes 2 and the opposite surfaces ofthe radiating blocks 4,- whereby a large-amount; of heat is transferred to the blocks and the pipes;

also 'the heat radiated from the blocks 4 and romthe interior surface of the pipes 2 is transferred to the inner refractorybodies `5.' At the same time, the air to be heated is admitted through the conduit A33- to the lowel` chamber 31 and passes upwardly as shown by the arrows 13 through the annular fiues 3 between the interior of the pipes 2 and the radiating bodies 5, escaping into Athe upper chamber 30 and out through the exitport 48 :provided for that purpose.

Here, as inthe case vof the hot gases, it will be observed that the air is passed through annular fines of narrow crosssectionV and hence can be readily moved at-a velocity equal or exceeding Tits* critical speed, whereby all the.pa rts of .theair are brought into intimate relation with the. interior of theV heating" pipes 2 andv the :exterior of the refractory bodies 5." 'As already explained, .thereis thus 'secured-.the very best, possi.- ble condition forthe 'transfer of heat at a high. rate from' the hot ,gasesV to the air.

vWith this apparatus,` it is clear that 'the l.air

is getting lwarmer and warmer as ityr'eaches a Ahigherlevel in. the pipes 2, while thehot l gases ,are cooleddown more and more as they reach`a lower level around the saine pipes 2.' The tubes and accessories of the upper section are consequently hotter than the same.

elements of the` intermediate section, these ments of the lower section. The advantage of this arrangement lis,'there for`e, that it Kis 'being themselves hotter than 4the same vele- 125 convection I may create eddies in the heating fluid for instance by stirring the latter by rotation of the group ofpipes. F1gs..12, 13, 14 and 15 show rotary .heat exchanging apparatus whereby this 1s accomphshed. Referring to Figs. 12 and (13, there is shown a rotary apparatus consisting of a stationary chamber 40 suitably supported on brackets 41. Under the chamber 40 is a rotatable chamber 42 and above the chamber 40 is another rotatable chamber 43, said chamber 42 having a partition 44 secured to and rotating therewith and said chamber 43 having a partition 45 secured thereto and likewise rotating therewith. Extending between the partitions 44 and 45 are pipes 2 affording open communication between the chambers 42 and 43. In the axis of the lower portion of the chamberI 42 is a cold air inlet 46 and in the axis of the chamber 43 is a hot air outlet 47. Hot gases are admitted to the chamber 40 through the con duit 92a, pass around the pipes 2 and take their exit through the waste gas outlet 49. The pipes 2 are provided with the interior refractory bodies and the spaces between the tubes are provided with refractor blocks as shown in Figs. 9, 10 and 11, all of those being omitted in Figs. 12 and 13 for the purpose of clearness ,of illustration. The chamber 42 rests upon the rollers 50, Fig. 12, and on its under side the chamber is provided with an annular rack 51 engaged by a pinion 52 driven by shaft 53 actuated by any suitable motor, not shown. When the parts are set in motion the lower chamber 42 and the upper chamber 43 together with the partitions 44 and 45 and the pipes extending therebetween are all rotated around a common axis. This prevents the high peaks of heat which would be produced in the nest of pipes and intermediate blocks around the inlet of the hot gases, it this part were stationary, with possible resultant damage to the various elements of the construction. This results from the fact that the zone of the a paratus which is subjected to the direct actlon of the incoming hot fluid is continuously or intermittently renewed, since it is apparent that the apparatus may be continuously or intermittently revolved, as desired. Moreover, by shifting the parts of the apparatus which receive the incoming hot fluid, the heat in that zone is greatly reduced, so that the transmission of the heat from the hot Huid in that part of the apparatus which depends upon the difference 1n temperature between the two is kept higher. While, as here shown,

the apparatus is operated with hot gases such as waste gases for example, the same may be just as readily supplied by the combustion of fuel gas, oil or other combustible burnt in a suitable manner and introduced through the conduit 92a. It will of course be understood that suitable joints 54, 54, are provided between the rotating and non-rotating parts to prevent any leakage between the stationary and the revolving 'parts thereof. These joints may be filled or instance with water, sand, tar, molten salts, molten lead, etc., depending upon the temperature and the inside pressure involved.

j Figs. 14 and 15 illustrate another form of rotary apparatus, especially adapted for the heating of air for instance, to high temperature. In this form the walls of the stationary chamber 40 are supported in any suitable manner, while the parts 44, 45 and the pipes 2 extending between them revolve with the parts 42 and 43 in a manner similar to that shown in Fig. 12. In the present instance, however, the pipes 2 are arranged in a plurality of groups and are connected to plates 44 and 45; if preferred, the pipes may be welded to the plates. The joints between the adjacent plates 44 and 45 are rendered tight in any suitable manner, as by use of asbestos impregnated with graphite, for example. The entire apparatus rests and revolves on rollers 50 and is driven by any suitable motor through pinion 52 and shaft 53. Within the pipes 2 are laced rods of radiating material 5 (Fig. 14 and the spaces between the pipes are filled with blocks of radiating material, not shown, constructed and arranged as previously explained in connection with Fig. 9. The cold air enters axially at the bottom through the inlet 46 and circulates upward through the annular spaces 3 between the rods 5 and pipes 2, as indicated by the arrows 13, and passes outwardly at the top as willbe clearly understeod by inspection of Fig. 14. The hot gases supplled by burner 55 or from any other desirable source, enter at the top of chamber 40, circulate around the several nests of tubes and the waste gases pass out through the waste pipe 49 in a manner similar to that shown in Fig. 12. Suitable joints 54, such as in Fig. 12, are also provided between the stationary and revolving parts. With this apparatus, it is clear that the air is getting warmer and warmer as it reaches a higher level in the pipes 2, while the hot gases are cooled down more and more as they reach a lower level around the same pipes 2. The tubes and accessories of the upper nest are consequently hotter than the same elements of the intermediate nest, these being themselves hotter than the same elements of the lower nest. The advantage of this arrangement is, therefore, that it is possible to make use for these several nests of pipes and their accessory equipment of materials progressively less refractory. The advantages of the rotation of the nests of pipes as already pointed out are lower peaks of heat with consequent safer operation, and greater eiiiciency in heat transmission.

' culated around the same.

It will be noted that a great many of the above apparatus or others which may be derived from the same invention, permit the replacement of the hot fluid by tie fluid to be heated and, vice versa, the replacement of the fluid to be heated by the hot fluid, that is to say, the hot fluid may be passed through the pipe-flues as above described, while`the Huid to be heated would be cir- This is but an obvious modification of the use of the apparatus, although, in principle, the efficiency `is generally lower than by the application of the process as heretofore described.

In brief, the flue-pipes as hereinbefore described may be made in one or several pieces, as desirable; they may have the most various cross-sections, more or less different from a circle, especially polygonal, oval,

` flat sections, etc. They may also be arranged in a devious or indirect course. But in every case, the total surface or perimeter governing the heat transfer shall be as hlgh as possible compared with the cross area of the passage left for the fluid; the thickness of their walls shall preferably be kept very small; these walls shall preferably be made of material as heat conductive as possible; the inner radiating bodies, when present, shall be constituted as explained hereafter; the fluid carried preferably circulated at a speed exceeding its critical velocity, and the length of travel of said fluid extended as much as possible. Practically, it is obvious that the above leading princ1ples shall be combined in various degrees according to local conditions.

It is also obvious that several apparatus of the above character can be connected in 46 series or in parallel, either to reach a given that the thin walls of the flues carrying 'the fluid to be heated, as heretofore dey scribed, may have to be built of various materials depending upon the temperature to which they are subjected and also the nature of the fluids coming in contact with them.

It is suflicient to say that generally speaking and for temperatures comparatively low, various metals such as copper, brass, iron, steel and the like may answer the purpose, while for higher tem eratures heat resisting alloys or compoun s, even special refractory potteries and fused silica may be necessary. In some of the drawings, the thin walls` are hatched differently from the rei fractory radiating bodies for purposes of illustration, but as explained above, said thin walls need not necessarily be of non-refrac tory material.

Since the intermediate radiating blocks and inner radiating bodies act mostly by their radiating power, it is suilicient that ally quite satisfactory for the purpose. Said intermediate blocks and inner bodies, however, may advantageously be constituted of porous materials with the result that the radiating power is then rather higher and the heat greatly diffused. This latter fact reduces the risk of hotspots which could be detrimental to the organs. Said blocks and inner bodies may also be constituted of refractory material molded to suitable shapes, porous or not, rings, pieces of pipes of the same substances, small castings perforated or not, piled up regularly or in bulk, with or Without interstices, into the spaces to be filled in or between the pipe-fines. The interstices eventually left by these assemblages, and eventually the pores of the materials, serve as passages to the fluids. This arrangement is generally favorable to obtainmg a high ra iating power; it is especially efficient 1n diffusing the heat and preventing high peaks of heat in certain zones of the apparatus.

It is indeed well known that three or four hot blast stoves are at present required per blast furnace and that the efliciency of such stoves attains only 50% to 65% notwithstanding the considerable height which is given to the apparatus, that is, the considerable length of travel which is provided for the circulation of the fluids.- On the contrary, the application of the present invention permits of attaining an eflciency easily exceeding 85% and even 90%, with only one blast heating apparatus per blast furnace (or two for reason of safety), each such apparatus being much smaller than one of the present time hot blast stoves of same capacity. The smaller volume of installation of course entails smaller radiation losses which enter into account in the high eiliciency observed.

While the invention has been described `with considerable particularity, it is to be understood that various changes may be made in the detail of application of the same, as will be readily understood by those skilled in the art, while certain features may be used without other features thereof. Reference is therefore to be had to the appended claims for a definition of the limits of the invention.

1. In heat exchanging apparatus of the the heat radiated y the same type operating with continuous passage of two Huids between which the heat exchange occurs, the combination of a mass of refractory bodies having multiple fluid passages, a thin flue wall of high conductive material located in said mass but with a narrow fluid passage between said Hue wall and the bodies composin said mass, and a mass of refractory material within said Hue but with a narrow Huid passage between said inner mass and the interior wall of said Hue.

2. In heat exchanging apparatus of the type operating with continuous passage of two Huids between which the heat exchange occurs, the combination of a thin walled spiral Hue with refractory material within and surrounding the spiral and so spaced therefrom as to leave a passage ofnarrow cross-section between said refractory material and the wall of said Hue.

3. In heat exchanging apparatus of the type operating with continuous passage of two Huidsbetween which the heat exchange occurs, the combination of a plurality of thin walled Hues with masses of refractory material so arranged between the Hues as to leave a passage of narrow cross-section between the refractory material and the flues, said masses of refractory material being provided with a multiplicity of restricted passages through ,or within the same for the Huid.

4. In heat exchanging apparatus of the type operating with continuous passage of two Huids between which the heat exchange occurs, the combination of a plurality of Hues for conducting one of the Huids with masses of refractory porous material in the spaces intermediate said Hues and surrounding the latter butspaced slightly therefrom to provide narrow passages for the other Huid.

5. In heat exchanging apparatus of the type operating with continuous passage of two Huids between which the heat exchange occurs, two adjacent Hnes each having a wall of heat-radiating refractory material, and a partition of thin, heat-conducting material forming one of the walls of each Hue.

6. In heat exchanging apparatus of the type operating with continuous and sim u1- taneous passage of two Huids between which the heat exchange occurs, the combination of a wall, preferably very thin and highly heat conductive under operative conditions, for separating the two Huids, and of adjacent radiating bodies otherwise limiting on each side of said wall the Hues provided for the two Huids, whereby the heat imparted to the fluid to be heated comes artly from a direct exchange of heat througlh the separat ing wall, partly from the heat radiated by one of the radiatin bodies, and artly from body which is then absorbed and afterwards radiated or given up by the second radiating body.

7. In heat exchanging apparatus of the type operating with. continuous and simultaneous passage of two fluids between which the heat exchange occurs, the combination of a Hue with walls preferably very thin and highly heat conductive under operative conditions, of an inner body, preferably made of material highly heat radiating under operative conditions, whereby there is obtained between said Hue and inner body a narrow passage for one of the Huids, and of another body, preferably made of material highly heat radiating under operative conditions, surrounding said Hue and' so spaced therefrom as to leave therebetween a narrow passage for the second Huid.

8. In heat exchanging apparatus of the type operating with continuous and simultaneous passage of two Huids between which the heat exchange occurs, the combination of a spiral Hue having a wall preferably very thin and highly heat conductive under operative conditions, with a refractory material, preferably highly heat radiating under operative conditions, within said Hue and surrounding the spiral and so spaced therefrom as to leave a passage of narrow cross-section for one of the Huids, between aid refractory material and the wall of said 9. In heat exchanging apparatus of the type operating with continuous and simultaneous passage of two Huids between which the heat exchange occurs, the combination of a spiral Hue, having preferably a small crosssection, and walls very thin and highly heat conductive under operative conditions, with a refractory material, preferably highly heatradiating under operative conditions, surrounding said Hue and so spaced therefrom as to leave a passage of narrow crosssection for one of the Huids betweensaid 1refractory material and the walls of said 10. In heat exchanging apparatus of the type operating with continuous and simultaneous passage of two Huids between which the heat exchange occurs, the combination of a plurality of concentric tubular members, having preferably walls very thin and highly heat conductive, with an inner refractory body inserted in the smallest tubular member, whereby there is obtained therebetween a plurality of passages, preferably very narrow, through which one of the Huids is conducted successively and along directions successively reversed, the largest of the said tubular -members being sur#` rounded with a radiating body coming in close proximity therewith, so as to leave a narrow passage or narrow passages for the second Huid between said largest tubular member and surrounding body.

11. The method of securing exchange of heat between two fluids, which consists in moving said fluids separately, on opposite sides of a thin highly refractory conductive and radiating partition, one of said fluids being moved at high speed and in a thin layer between said partition and a closely arranged facing body of highly refractive and radiating material, and simultaneously developing turbulence in said fluids, whereby heat exchange is secured between the two bodies by the simultaneous action of conduction, radiation and convection.

12. In an apparatus for securing exchange of heat between two fluids, the combination of two conduits for the two fluids having a common wall of thin highly conductive and radiating material and outer walls of refractory radiating material, whereby simultaneous intensified heat exchange by conduction, radiation and convection is secured between the two fluids,`said conduits being formed to create eddies in the fluids passing therethrough.

13. The method for effecting transfer of heat from a heating gas to a gas to be heated through the medium of a diaphragm which comprises transferring heat by convection from the heating gas to the diaphragm, thence by conduction through the diaphragm, thence directly by convection to the gas to be heated and indirectly by radiation to a heat absorbing body positioned in the path of the gas to be heated and by convection from the surface of said body to said gas. D 14. The method for effecting transfer of heat between a heating gas and a gas to be heated through the medium of a diaphragm which comprises transferring heat from the heating gas directly by convection to the diaphragm and indirectly, by convection to a heat absorbing and heat radiating body positioned in the path of the gas and thence by radiation to the diaphragm, passing heat thus transferred, by conduction through the diaphragm, and transferring such heat from the surface of the diaphragm directly by convection to the gas to be heated and indirectly by radiation to a heat absorbing body positioned in the path of the gas to be heated and thence by convection from the surface of such body to said gas.

15. The method of effecting heat transfer between a moving body of hot gas and a moving body of cold gas through the medium of a diaphragm which comprises transferring heat by convection from the lhot as to the diaphragm thence by conduction through the diaphragm, and thence by radiation to a heat absorbing body and by convection from said body to the cold gas.

16. The method for effecting transfer of heat from a moving body of hot gas to a moving body of cold gas through the medium of a diaphragm which comprises transferring heat carried by the hot gas by convection to a heat-absorbing body and thence by radiation to the diaphragm, thence by conduction through the diaphragm, and thence by radiation to a heat absorbing body and by convection from said last named body to the cold gas.

17. The method for effecting heat transfer between a heating gas and a gas to be heated which comprises absorbing heat froln said heating gas transmitting heat thus absorbed to one side of a heat conductant diaphragm by radiation, thence by` conduction through the diaphragm, thence directly by convection to the gas to be heated and indirectly by radiation to a heat absorbing body positioned in the path of the gas to be heated and by convection from the surface of said body to said gas.

18. The method of effecting efficient transfer of heat from a gaseous heating body to a gaseous body taking up heat through the medium of a metal diaphragm which comprises transferring heat from the heating gas to the metal, placing a refractory body having relatively. large bulk and surface area in the path of the gas taking up heat to absorb heat radiated from the metal and to transmit it by convection to the gas, and utilizing the heat storage capacity of the refractory to continuously furnish heat to the gas during intervals in which the volume of heat radiated from the metal is reduced.

19. Apparatus for .effecting transfer of heat from a heating gas to a gas to be heated through the medium of heat conducting walls which comprises a housing, partition walls of heat conducting material extending therethrough, means for passing gas to be heated along one surface of said Walls and out of contact with heating gas passing along-the opposite side of said walls, bodies of refractory material positioned in the path of the heating gases facing and spaced from the surface of the heat conducting walls, and other bodies of refractory material in the path of the gas to be heated and facing and spaced from the opposite surface of the Walls.

20. Apparatus ;for effecting transfer of heat from a heating gas to a gas to be heated through the medium of metal walls which comprises a housing, metal conduits extending therethrough and arranged to keep gas to be heated out of contact with heating gas, means for passing gas to be heated through the conduits, means for passing heating gas through the housing in contact with the outer surface of the conduits, and cores of refractory inside the conduits having relatively large heat absorbing and heating surfaces facing and spaced from the inner surface of the conduit.

21. Apparatus for eiecting transfer of heat from a heating gasto a gas to be heated through a medium of metal walls which comprises a housing, a plurality of metal conduits extending longitudinally therethrough, means for passing a heating gas incontact with the outer surface of said conduits and means for passing a gas to be heated through said conduits, and cores of relatively bulky refractory having a substantial heat storage capacity in said conduits with a relatively large heat absorbing surface facing and spaced from the inner wall of the conduit to absorb heat radiated from the metal wall and to supply heat continuously to gas owing between the outer surface of the core and the inner surface of the metal.

22. Apparatus for exchange of heat between two iuids moving separately on each side of a thin partition, one fluid at least being circulated at high speed and in a thin l around which are arranged the refractory bodies. i

23. In a method for the exchange of heat between two fluids according to claim 12, the step of imparting additional turbulence to one Huid to increase heat transfer resulting from convection by moving the ues in which the other iuid circulates.

24. In an apparatus according to claim` 13, means for moving one of said conduits whereby: turbulence is imparted to one of the fluids and the heat exchange resulting from convection is increased.

J. Louis CHAVANNE.

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