US2534448A

US2534448A - Fluid-cooled tube for sighting a furnace pyrometer

Info

Publication number: US2534448A
Application number: US604409A
Authority: US
Inventors: Jantsch Emil
Original assignee: Carnegie Illinois Steel Corp
Current assignee: Carnegie Illinois Steel Corp
Priority date: 1945-07-11
Filing date: 1945-07-11
Publication date: 1950-12-19
Anticipated expiration: 1967-12-19

Description

Dec. 19,` 1950 E. JANTscH FLUID cooLED TUBE FOR SIGHTING A FURNACE PYROMETER 4 Sheets-Sheet l Filed July ll, 1945 IN'VENTOR E'm/ rig/7K c/l BY f] ATToRN E. JANTSCH Dec. 19, 1950 FLUID COOLED TUBE FOR SIGHTING A FURNACE PYROMETER 4 Sheets-Sheet 2 Filed July 11, 1945 INVENTOR 7m/7 Janis@ ATTOR Y Dec. 19, 1950 E. JANTSCH Y 2,534,448

FLUID COOLED TUBE FOR SIGHTING A FURNACE PYROMETER Filed July 11, 1945 4 Sheets-Sheet 5 Jig. 7. 60,

INVENTOR m/ Jan sc/2 BY ATTORNEY Dec. 19, 1950 E, JANTSCH 2,534,448

FLUID COOLED TUBE FOR SIGHTING A FURNACE PYROMETER Filed July 1l, 1945 4 Sheets-Sheet 4 INVENTOR ATTORN Patented Dec. 19, 1950 UNITED STATS TNT orrici:

FLUID-COOLED TUBE FOR SIGHTING A FURNACE PYROMETER Emil antsch, Youngstown, Ohio, assignor to Carnegre-Illinois Steel Corporation, a corporation of New Jersey 14 Claims.

This invention relates to a cooled tube adapted for mounting in high temperature apparatus, and characterized by a novel, simple, and eiicient cooling means.

The invention has among its objects the provision of an improved water-cooled pyrometer tube for furnaces and the like.

i A further object of the invention resides in the provision of a jacketed heat exchange device, such as a, water-cooled pyrometer tube, so constructed that heat exchange takes place uniformly throughout its extent, that it may be easily dissassembled for cleaning whereby it is simple to maintain, and that it will have a long service life.

These and other objects of the invention will be made more fully apparent in the following description.

The device of my invention because of its simplicity, ease of maintenance, and uniformity of heat transfer is capable of use to advantage in a variety of applications requiring the transfer of heat, and it may be made in a variety of shapes, depending upon the use to which it is put. For the sake of simplicity it will be described, however, in that modification in which it is tubular in shape. Although the tube is herein- `after spoken of as a water-cooled tube, it may in some instances be employed so that the now of heat is reversed and the tube is heated rather i than cooled. Furthermore, uids other than water may be employed as the cooling agent. The tube is illustrated and described herein, however, in connection with its use as a watercooled pyrometer tube on a furnace, in which g use it displays perhaps the maximum advantages.

In high temperature heating furnaces, such as those for heating steel billets, the temperature of the billets is measured by means of a radiation pyrometer trained through a furnace opening upon the billets in the nal heating zone. Ln the interests of accuracy of the measurement of such temperature, itis necessary to choose the line of sight of the pyrometer as short as possible and to maintain such line of sight free from` opaque gases. For this reason, there is customarily employed a pyrometer tube extending into the furnace in close proximity to the articles whose temperature is to be measured. As a consequence, the inner end of the tube is subjected to very high temperatures, which in the case of a reheating furnace may be in the order of 3000 F. In order to give the pyrometer tube as long a life as possible in such extreme conditions of service, it has been customary to cool the tube by means of a water jacket. Such prior water jacketed pyrometer tubes have not been entirely satisfactory however, since they have been prone to local overheating with resultant steam binding and have frequently caused the creation of a fog within the tube in the line of sight by reason of the cooling of the inner suris caused to ow uniformly into contact with every portion of the tube surface. Means are provided whereby the cooling water flows first in one direction and then the other along a tube through metered inlet and outlet ports, the Water being so baffled as to flow mainly in lines parallel to the axis of the tube. There is further provided a novel means for purging the atmosphere in the sight line in the tube and removing the condensate therefrom so that such atmosphere is caused to follow a definite path and is positively removed. As one of the preferred embodiments of the invention, there is further provided means whereby a mixture of air and water may be employed as a cooling medium, and whereby the mixture is agitated in the desired degree to accomplish optimum cooling.

The invention will be more readily understoodby reference to4 the accompanying drawings, in-

which Figure 1 is a view in vertical section longiv tudinally through a billet reheating furnace em ploying the pyrometer tube of the present invention;

Figure 2 is a View in vertical section through a pyrometer tube made in accordance with the present invention;

Figure 3 is a view in horizontal cross section,

said section being taken along the line III--IIIv of Figure 2;

Figure 4 is a view in horizontal cross section through the pyrometer tube taken along' the may, however, be mounted in various positions including that in which it is upside down and substantially vertical. In such case, ring 62 functions to collect condensate which may trickle down the inner surface of wall I8, such condensate flowing from the inner concave surface of the ring out the hole or holes 64, such flow being aided by the pressure of the purging gas.

To insure the travel of the cooling fluid the full length of the pyrometer tube and its return over the same length of travel as well as to govn ern flow of such fluid .circumferentially of the tube, there is provided an intermediate dividing tube or balile between the walls It and I8. In the modification shown in Figure 2, such dividing tube 66 is made in the form of a prolongation of the-cylindrical"wall-portion Sil-f the expansible element 28. Tube 66 may be conveniently made separately and subsequentiy welded to the bottom portion of the wall 34. As shown in Figure 4, dividing tube 66 is provided in the vicinity opposite the inlet manifold 22 with a plurality of equally spaced corrugations $8 parallel to the axis of the tube, such corrugations being suicient in number and so spaced relative to the holes 25 as to divide the cooling space between the outer tube I6 and the dividing tube 65 into a plurality of equal chambers symmetrically located with respect to holes 25. Corrugations ESB are continued to the bottom of tube E6, said tube reaching to a point near, but somewhat spaced from the end I1 of tube i6 as shown in Figure 6. Thus the flow of water in such outer cooling space, the flow in the preferred modification being directed downward, takes place in a plurality of zones of equal extent, the water in each zone being of the same volume and having the same velocity. In order to insure further complete uniformity of cooling in such outer zone, the lower portion of dividing tube 55 extending from the point I4 opposite the point l2, at which the inner wall I8 is oifset to provide a larger diameter in the lower` portion thereof, is provided with a plurality of shorter corrugations It! intermediate each of the long corrugations 58. The structure of the dividing tube 66 at such lower portion is more clearly shown in Figure 5. Corrugations 10, which with corrugations S8 are equally spaced circumferentially of tube 66, are preferably somewhat more shallow than the radial distance between the inner and outer walls of walls I6 and I8, respectively, as are corrugations 68 below the point 14, so that narrow passages exist between such corrugations and the walls, thereby allowing equalization of ilow between such smaller divisions of the cooling space. In the main, however, it will be evident that the flow of cooling water within such smaller divisions will be in a direction axially of the tube.

Water thus fed downwardly in the outer cooling Zone between the outer hotter wall I6 and the dividing tube 66 ows around the lower end of the dividing tube as shown in Figure 6 and progressively upwardly in contact with the inner cooler surface of wall IS until it flows out of hoies 44 into the outlet manifold dd. Flow of the water in such inner cooling space will likewise be mainly in an axial direction due to the restraint imposed upon it by the rear surfaces of the corrugations 'lil and (i8, and for this reason flow and therefore cooling in such inner space will likewise be uniform. It is preferred that the direction of the cooling iiuid be as shown in Figure 2, in which the duid enters manifold 22, flows downwardly in the outer cooling space and upwardly in the inner cooling space. Such direction of flow allows the cooling fluid to be sufficiently heated by its flow in the outer cooling space so that it is at a temperature above the dew point of the gases within the pyrometer tube when it comes into contact with the inner wall I8. Thus there is no danger, as there would be if the cooling water were rst introduced into contact with the inner wall I8, that moisture will condense upon the inner surface of the tube and tend to form steam, thereby obscuring the sight line.

As shown in Figure 3, there are provided a pluralityr of equally spaced radial projections 'I6 on the inner surface of wall I8, such projections being of short axial extent to prevent disturbing the uniformity of iiow of the cooling iiuid into the exhaust manifold. Similar radial projections 'I8V are provided on the dividing tube 66 as shown in Figure 4 so that the dividing tube is maintained in concentric relationship with the inner wall I8 of the pyrometer tube. The lateral projections 'I6 and 'I8 function as baffles so as to cut down the tendency of the fluid to ow circumferentially of the spaces within which they are located, and thus aid in the maintenance of uniform flow at the same velocity of the iiuid through the compartments and sub-compartments of the tube.

In Figures 7 and 8 there is shown a modification of the pyrometer tube previously described, the main differences lying in the type of expansion joint provided between the inner and outer walls of the tube and in the means for supplying the cooling medium to the tube, whereby such medium may be agitated or its character modiied as desired. In Figures 7 and 8, parts of the pyrorneter tube, which are the same as those of the tube shown in Figures l to 6, inclusive, are designated by the same reference characters with an added prime. In the structure shown in Figures 7 and 8, the part interposed between the upper end of the outer wall i6 and the part 52' supporting the optical mounting 54 is not rigidly attached to such outer wall but is made slidable therein. Thus, sleeve 89, which is integral with the outlet manifold .lii', is provided on its lower end which extends within the upper end of wall IB' with a flange 82 carrying a packing 84 which forms a seal between the sleeve and the outer tube wall, said packing being held under oompression by a gland means subsequently to be described. The dividing tube 66 is attached to the lower surface of flange 82 so as to make a fluid tight connection, as by being welded thereto.

The lower end of nipple 52' is provided with a central axially extending integral threaded nipple 86 which is screwed into the threaded upper end of the inner wall I8 of the pyrometer tube to effect a seal between the nipple 52', the upper end of inner wall I8', and the upper end of sleeve 80 which is integral with the outlet manifold. Such manifold is provided with an inwardly directed flange 38 which extends between the upper end of wall I8 and the shoulder portion surrounding nipple 35 on nipple 52. Suitable packing material is provided between such flange and nipples 52', SB, and wall I8', so that upon the screwing down of nipple 52' a pressure tight joint is made between such parts.

Packing 84, previously described, is held under compression by the means shown in the central portion of Figure 7 and in Figure 8. Sleeve 80 is provided at a point beneath outlet manifold dil' with an outer threaded portion S3 on which is positioned the threaded nut S2. Interposed between nut 92 and gland 98, which surrounds the 'abseits vsleevi-Z-'and extends into contact 'with the :packing, isa split clamp Satire parts of which'are held together around the sleeve by means of bolts 9b. Upon the .screwing down 'of nut e2, therefore, gland 83 may be forced tocoinpress the packing Bil vbetween outer wall iii and sleeve t@ to effect apressure tight seal. At the saine time, however, sleeve 8E and conseciuently the upper end of iriner wall I8' are free to move axially relative to the outer wall i6 upon heating Yof the pyroineter tube in service.

lIn Figure '7 there is shown a supply pipe equipped with a shut-off valve '9i' whereby Va further cooling medium 'oi-a type different fron'i'that supplied bythe source to which supply pipe 2li is connected may be delivered to 'thezpyrometer tube. In some instances it is preferred to intro#- duce 'compressed air into the cooling medium through pipe 95, the main cooling medium being water introduced through pipe 2t. Such air, which is introduced at a pressurein excess 'of that at which the water is supplied, mixes with the water flowing into the pyroineter tube cooling jackets -so as to agitato the water stream continuously by the air bubbles passing through it,

thereby keeping impurities in the water mixed therewith and in suspension, and preventing their attachment to the interior surfaces of the water passages. vvSuch arrangement, which has been found particularly valuable where the coo-ling ter supplied is frequently dirty, liminates 'or greatly reduces the need for periodic cleaning the cooling jackets.

Figures 9 and l0 'show two further modifications of the pyrometer tube, the differences between such modications and those previously 'described residing in the means by which the outer inner cooling spaces between the outer and in er walls of the tube are formed. In Figure 9, v uch is a view in cross section through the lower por tion of the modined pyroineter tube, there is proa vided a double walled tube having an outer wall lili] and an inner wall HB2, the space between such walls being divided by a ribbed dividing tube lull, the ribs extending radially `irorn the inner and outer 'surface of the dividing tube as y'shown an-d longitudinally thereof in an axial direction. Outer ribs H35, of which three are shown equally spaced about tube Iti, correspond in function and in 'axial extent to the long `corrugation t3 of the dividing tube @ii oi the first modification above described. Intermediate between adjacent ribs Iil area plurality of equally spaced ribs iet corresponding in function and axial extent to the shorter `corrugations 'ES on the dividing tube oi the iirst modification. Tube it is provided with a plurality of equally spaced radial projections l lil for the division of the inner cooling space into equal axially extending sections to insure uniformity of cooling.

In the still further modification shown in Fig ure 10 division of the inner and outer cooling spaces between the outer wall H2 and. the inner wall lili of the double walled pyrometer tube is accomplished by providing both the outer surface of the inner wall Mil and the outer surface ot dividing tube H6 with a plurality of outwardly radially described axially extending projections. Three of such projections shown as i it are equally Vspaced therea'ibout and correspond in function and in axial extent to the corrugations 68 in the first modification above described. rlhe other outer projections |29 on the dividing tube equally spaced between projections H8, as well as pro- Elections 422 on the inner wall lili, are of shorter 8 l extent axiaiiyysince they correspond vto coi-ruga-A tions i in the rst modication and servetodivide the lower parts of the inner and outercoling spaces equally circumferentially of the tube.

Two still further modifications ci the cooling jacket structure of the pyrometer tube'are shown in Figures ll and l2. In some instances it lhas proved desirable to cause the cooling fluid inthe inner and outer cooling jackets of the tube 'to travel in directions other than purely axially of the tube. In Figure il the cooling fluid, such as water, is caused to iiow through the inner and outer cooling spaces infhelical paths by providing a dividing tube 128 positioned between outer wall |24 and inner wall l2@ with helicalcorrugations or ribs, corrugations being shown inthe drawing. Certain of such corrugations or ribs #'32 equally spaced circumferentially about the dividing tube are provided at their upper ends with axial 'corrugations or ribs dividing the upper `portieri of the outer cooling space into equal Zones. Theremainder of such corrugaticns or ribs itil are made without such upper extensions and serve to d-ivide such large cooling zones into smaller equal zones. y

In Figure l2 the water within the cooling spaces is caused to travel in a sinuous direction by the provision of dividing tube E33 between outer 'wall itil and inner wall itt, said dividing tube being provided with a plurality of equally spaced Vsiriuous corrugations or ribs extending generally axially of the tube, corrugations being shown in the drawing. As in the case of previous modiiica; tions, certain of said corrugations or ribs i512 equally spaced circumferentially of the tube are made longer than the other corrugations or ribs Ult. Such increased length is provided by straight corrugations or ribs joining with the tops of corrugationsior ribs i132 for the purpose of dividing the cooling spaces in the plurality of equal zones, the other corrugations ille serving to equal a plurality of smaller equal zones. v

In some instances, as where the pyrometer tube of the present invention is used under particularly extreme conditions and is subjected to very high temperatures, it has proved desirable to provide it on its outer and lower surface thereof with an insulating layer to retard the ilo'w of heat thereinto. In Figure 13 the lower end of the pyrometer tube so made is shown, the 'tube consisting of an outer wall ide, an inner wall MQ, and a corrugated dividing tube Mit. On the outer surface or" wall it@ and on the lower end of 'the double wall there are provided a plurality ci spaced projections l which may be in the form of studs welded to the outer tube wall. A layer l52 of high temperature insulating material, which is capable or withstanding temperatures to which the exterior of inner end of the pyronieter tube is exposed, is applied to the outer surface of the outer wall a layer H56 of insulating material applied at the bottom of the double walled tube as shown, studs i552, which are embedded therein, serving to hold the insulation firmly on the tube.

It will be apparent from the foregoing description that in the preferred method of cooling the tube of the' present invention, in which the cooling medium flows first into `Contact with the outer hotter wall ci the tube and thence into contact with the inner cocier wall thereof, such medium is introduced, in the modiiication first described, through .pipe 2li to manifold 22, trom which it liows through the spaced holes 25 into the upper portion of the outer cooling space. The water then flows downwardly axially of the tube within the equal zones dened by the long ribs or corrugations from the manifold, the openings therefrom into the outer cooling space and the dividing corrugations or ribs being so constructed and arranged that equal volumes of water flowing at equal velocities are in contact with the outer wall of the tube at all points. The further shorter equaly spaced corrugations or ribs insure that such condition is maintained throughout the en tire length of the outer cooling space and also upon the return flow of the water in contact with the inner cooler wall. The division of the outer and inner cooling spaces in the manner described provides a plurality of passages in which the cool* ing fluid flows in thin sheets at a high velocity, thereby continuously scouring off the thin layer of steam er stagnant heated water which would otherwise tend to form in contact with the heated surface of the tube walls.

The manner in which the iiow of .cooling medium accomplishes this result is illustrated schematically in Figures 14 and 15 in connection with the operation of the first modification of the pyrometer tube. The downwardly flowing cooling stream of water W in the outer cooling space between the outer wall I and the dividing tube 65 is constantly met in its downward travel with the rising currents R of hot water from the inner wall of the outer tube l5. Such stream W, which travels at high speed, tends constantly to shear such rising currents R from the wall Iii, causing them to intimately mix with the incoming water. At the same time steam bubbles S are also removed from the tube wall and are uniformly distributed through the cooling Water so that they are caused to be condensed, thereby preventing any local accumulation of steam in the -cooling jacket with resultant steam binding of the cooling system. When the corrugated dividing tube 66 is employed, the curve of such corrugations causes a further agitation of the cooling medium and a mixing of the incoming cooling water and the layer of hot water and steam coming off the tube wall. As shown in Figure l5, in a horizontal section of a portion of the pyrometer tube, such heated water and steam tend to travel laterally in each division of the outer cooling space in the directions indicated by the arrows R'. When the stream of cooling uid W impinges upon such currents R', a very thorough mixing of the hot and cold water results with a consequent efficient removal of heat from the outer tube wall. The same thorough mixing of relatively cool and heated water and steam takes place in the inner cooling space, the direction of the relatively cool water in its return flow being indicated by the arow W'.

The pyrometer tube made in accordance with the present invention is characterized by the ease with which it may be disassembled for cleaning when necessary, as well as by the advantages as to uniformity of cooling, absence of steam binding, and the maintenance of a clear sight line, above set out. Thus, in the modification shown in Figures 2 to 6, inclusive, the tube may readily be disassembled, after the disconnection of the `inlet and outlet cooling medium tubes and the removal of the pyrometer tubes from the furnace by removing the bolts holding flanges Z, 3b and 38, 48 together. Thereupon plate 48 may be unscrewed from the upper end of inner wall I8 of the double walled tube, and joint 28 and dividing tube B lifted out for inspection and cleaning. The modication shown in Figures l and 8 may likewise y be easily disassembled Iwhen desired.

This is effected by the loosening of nut 92, and of clamp 94, the inlet and outlet cooling tubes having been disconnected and the pyrometer tube removed from the furnace, so that sleeve 80, and consequently dividing tube 66' may be pulled axially out of the pyrometer tube.

Having thus fully described and illustrated preferred embodiments of the heat exchanger and more particularly the water-cooled pyrometer tube disclosed as a specific example of the present invention, I now desire to claim as new the following.

I claim:

1. A tubular heat exchanger comprising a double walled tube having an outer wall and an inner wall spaced radially therefrom to provide a heat exchanging medium receiving space between them, means joining the outer and inner walls of the tube at one end thereof to form a iiuid tight joint, a dividing tube in the space between the tube walls to separate the space into an inner and an outer compartment each extending longitudinally of the tube, said tube extending to a point in the region of but somewhat spaced from the juncture between the inner and outer tube `walls where the compartments join, means substantially to divide the inner and outer compartments into generally axially extending subcompartments, means to direct fluid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide a predetermined quantity of fluid at a predetermined velocity in each sub-compartment thereof, and means to exhaust the fluid from the other compartment in a direction away from the closed end of the double Walled tube in such manner as to provide a predetermined quantity of uid at a predetermined velocity in each subcompartment thereof, said last two named means comprising means at a point remote from the joined ends of the double walled tube to form a, seal between the outer tube wall and the dividing tube, means at a point remote from the joined ends of the double walled tube joined to the dividing tube to form a seal between the inner tube wall and the dividing tube, a manifold about the outer tube wall near the first sealing means, a series of passages through the outer tube wall within the manifold communicating lwith the outer compartment, a second manifold about the means joined to the dividing tube, and a series of passages through the means joined to the dividing tube within the second manifold communicating with the inner compartment.

2. A tubular heat exchanger comprising a double walled tube having an outer wall and an inner wall spaced radially therefrom, means joining the outer and inner walls of the tube at one end thereof to form'a fluid tight joint, an intermediate single-walled dividing tube to divide the space between the tube walls to separate such space into an inner and an outer compartment, each extending longitudinally of the tube to a point in the region of but somewhat spaced from the juncture of the inner and outer tube walls where the compartments join, means substantial- 1y to divide the inner and outer compartments into axially extending sub-compartments, means to direct fluid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide substantially equal quantities of fluid at substantially the same velocity in each sub-compartment thereof, and means to exhaust the fluid from the other compartment in a direction away from the closediendof the double walled tube in such manner 'as to provide substantially equal quantities of iiuid at substantially the same velocity in each sub-compartment thereof, said last named means comprising means joined to the dividing tube at a point remote from the-joined ends of the double walled tube to form a seal between theouter tube wall and the dividing tube and to form a seal betweenthe inner-tube wall and the dividing tube, said`last-mentioned means including spaced exible diaphragmsand a fluid-exhausting manifold located between said diaphragms.

3.4 A tubular heat exchanger comprising a double walled tube having an outer wall and a substantially coaxial inner wall spaced radially therefrom to provide a heat exchanging medium receiving space between them, means joining the 'outer and inner walls of the tube at one end thereof to form a iuid tight joint, a dividing tube inf the? space between the tube walls to separate thev space into an inner and an outer compartment each extending longitudinally of the tube. saiol-` tube extending to a point in the region of but-somewhat spaced from the juncture between th'inne'r and outer tube walls where the compartments join, means substantially7 to divide the inner and outer compartments into generally axially extending sub-compartments, means te direct fluid into one of the compartments in a direction toward the closed end of the double walled tube in'sucli manner as to provide substantially equal quantities of uid at substantially-the samevelocity in each sua-compartment thereof, and'means to exhaust the uid from the other compartment in a direction away from the closed end of the double walled tube in such manner asto provide substantially equal quantities offluidat substantially the same velocity in each sub-'compartment thereof,` said last two named means comprising means at a point remote from the j oined ends ofthe double walled tube to form as'ealbetween theouter tube wall and the dividing tube, means at a point remote from the joined ends-of the double walledrtube joined to the dividingvtube to form a seal betweenl the inner tube wall and the dividing tube, a manifold about the outer tube wall near the iirst sealing means, said manifold being of volute shape and having a conduit connected thereto at the location of maximum cross-section, a series of equally spaced passagesrthrough the outer tube wall within the manifoldcommunicating with the outer compartment, a second manifold aboutl the means joined to the dividing tube, said manifold being of volute shape and having a conduit connected thereto at the location of maximum cross-section, and a series ofequally spaced passages through such means joined to the dividing tube within the secondA4 manifold communicating with the second compartment.

4'. A tubular heat exchanger comprising a double-walled tube having an outer wall and an inner wall coaxial thereof and spaced radially therefrom, means ljoining the outer and inner walls of the tube at one end thereof to form afluid tight joint, an intermediate dividing tube to divide the space between the tube walls to separate such space into an inner and an outer compartment, each extending longitudinally of the tube to a point in the region of but somewhat spaced from thejuncture of the inner andv outer tubeY walls where the compartments join, means substantially t'o divide the inner and outer compartments direction toward the closed: end of the double walledv tube in such manner asto providev substantially equal quantities of uidat substan. tially the same velocity in each sub-compartment thereof, and means to exhaust the fluid from the other compartment in a direction. away fromA the closed end of the double walled tube insuch manner as to provide substantially equal quantities of fluid at substantially thev same velocity in each sub-compartment thereof, said last named means comprising means generally in the form ofa tubularl extension joined to the dividing tube at a point remote from the joined ends of thedouble walled tube to form a seal between the outer tube wall and the dividing` tube and to form a seal between the inner tube wall and the dividing tube, said tubular extension being provided with a iiexiblediaphragrn between the dividing tube and its point ofconnection tothe outer wall of the double walled tube and with a flexible diaphragm between the dividing tube and its point of oonne'ction to theinner wall of the double` walledtube to permit longitudinal expansion or contraction of the outer and inner tube walls relative to each other, said fluid-exhausting means. being disposed between said flexible diaphragms.

5'. A tubular heat exchanger comprising a double walled tube having anY outer wall and an inner wall coaxial thereof andspaced radially therefrom, means joining the outer and inner walls of the tube at one end thereof to form a uid tight joint, an intermediate dividing tube to 'divide theV space between the tube walls toseparate such space into an Ainner and an outer compartment, each extending longitudinally of thevtube to a point in the region of but somewhat spaced from theY yjuncture of the inner and outer tube walls where the'compartments join, means substantially to divide the inner, and outer compartments into ,axially extending sub-compartments, means to direct fluid into one of the compartments in a direction toward the closed end ofthe double walledtube in such manner as to provide substantially equal quantities of'fluid at substantiallythe same` velocity in each sub-cornpartm,entv thereof, and means to Vexhaust the uid from the otherlconfipartment,in,A a di rection away from the closed end off the double walled tube in such manner as toprovide substantially equal quantities of uid at substantially the sameV velocityl in, eall sub-comparte ment thereof, said last twonam'ed'means comprising means generally in the form of` a rigid tubular extension joinedto the dividing tubek a point remote from the joined endsjof the double walled tube to form ajse'al, between. the outer tube wall and the dividing tube and rigidly joined tothe inner tube wallv to formjarseal be` tween the inner tube wall and the dividing tube, the tubularV extension having one,v end in tele scoped relationship with theen-d of therouter wall of the double walledtubaand; a *packing means between the tubular extensiqnra'nd'the,outerwall permitting longitudinal nilovementof` the exten,- sionrelative to the outerwall to.,'permitl'ongiY tudinal expansion or contraction of the outer, and inner tube walls relative',toeachV other.

6, A fluid-cooled tube comprising ay maiubody.

Y made upof a double Walled tube havingan outer.

wall and an f inner wall spaced radially. therefromY to provide'aheat exchangingjmedium receiving spaced between them, there being Van unobstructed bore within the inner wall of the tube to provide a line ofV sight through the'tube means joining the outer andY inner walls ofthe tube'.

at one 'end thereof to form a uid tight joint, a dividing tube in the space between the tube walls to separate the space into an inner and an outer compartment each extending longitudinally of the tube, said tube extending to a point in the region or but somewhat spaced from the juncture between the inner and outer tube walls where the compartments join, means substantially to divide the inner and outer compartments into generally axially extending subcompartments, means to direct cooling fluid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide substantially equal quantities of iiuid at substantially the same velocity in each sub-compartment thereof, means to exhaust the uid from the other compartment in a direction away from the closed end of the double walled tube in such manner as to pro vide substantially equal quantities of fluid at substantially the same velocity in each sub-compartment thereof, means to introduce purging gas into the bore within the inner wall of the double walled tube in a direction toward the joint between the inner and outer walls thereof, an annular projection inwardly of the bore from the point of application of the purging gas and at least one passage immediately inwardly of the annular projection to allow the escape of gas therefrom.

7. A duid-cooled tube comprising a main body made up of a double walled tube having an outer wall and an inner wall spaced radially therefrom to provide a heat exchanging medium receiving space between them, there being an unobstructed bore within the inner wall of the tube to provide a line of sight through the tube means joining the outer and inner walls of the tube at one end thereof to form a iiuid tight joint, a dividing tube in the space between the tube walls to separate the space into an inner and an outer compartment each extending longitudinally of the tube, said tube extending to a point in the region of but somewhat spaced from the juncture .between the inner and outer tube walls where the compartments join, means substantially to divide the inner and outer compartments into generally axially extending sub,- compartments, means to direct cooling uid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide substantially equal quantities of fluid at substantially the same velocity in each sub-compartment thereof, and means to exhaust the uid from the other compartment in a direction away from the closed end of the double walled tube in such manner as to provide substantially equal quantities of duid at substantially the same velocity in each subcompartment thereof, said last named means comprising means at a point remote from the joined ends of the double walled tube to form a seal between the outer tube wall and the di viding tube, means at a point remote from the joined ends of the double walled tube joined to the dividing tube to form a seal between the in ner tube wall and the dividing tube, a manifold about the outer tube wall near the first sealing means, a series of passages through the outer tube Wall within the manifold communicating with the outer compartment, a second manifold about the means joined to the dividing tube, a series of passages through such means joined tc the dividing tube within the second manifold communicating Vwith the inner compartment,

and means to introduce purging gasr into the bore within the inner wall of the double walled tube in a direction toward the joint between the inner and outer walls thereof.

S. A duid-cooled tube comprising a main body made up of a double walled tube adapted to be mounted so that its forward end projects through a wall of a furnace, said tube having an outer wall and an inner wall coaxial thereof and spaced radially therefrom, there being an unobstructed bore within the inner wall of the tube to provide a line of sight through the tube means joining the outer and inner walls of the tube at the forward end thereof to form a uid tight joint, an intermediate dividing tube to divide the space Vbetween the tube walls to VseparateV such space into an inner and an outer compartment, each extending longitudinally of the tube to a point in the region of but somewhat spaced from the juncture of the inner and outer tube walls Where the compartments join, means substantially to divide the inner and outer compartments into axially extending sub-compartments, means to direct cooling uid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide sub stantally equal quantities of uid at substantially the same velocity in each sub-compartment thereof, means to exhaust the fluid from the other compartment in a direction away from the closed end of the double walled tube insuch manner as to provide substantially equal quantities of uid at substantially the same velocity in each sub-compartment thereof, said last named means comprising means joined to the dividing tube at a point remote from the joined ends of the double walled tube to form a seal between the outer tube wall and the dividing tube and to form a seal between the inne;1 tube wall and the dividing tube, said last named means each including a flexible diaphragm, one on each side of the uid-exhaust means to permit expansion or contraction of the outer and inner tube walls relative to each other while maintaining the seals, and means to introduce purging gas into the bore within the inner wall of the double walled tube in a direction toward the forward end of the tube adapted to be positioned inside the furnace.

9. A fluid-cooled tube comprising a main body made up of a double walled tube adapted to be mounted so that its forward end projects through a wall of a furnace, said tube having an outer wall and an inner wall spaced radially therefrom to provide a heat exchanging medium receiving space between them, there being an unobstructed bore within the inner wall of the tube to provide a line of sight through the tube means joining the outer and inner walls of the tube at the forward end thereof to form a iiuid tight joint, a dividing tube in the space between the tube walls to separate the space into an inner and an outer compartment each extending longitudinally of the tube, said tube extending to a point in the region of but somewhat spaced from the juncture between the inner and outer tube walls where the compartments join, means substantially to divide the inner and outer` compartments into generally axially extending subcompartments, means to direct cooling fluid into one of the compartments in a direction toward the closed end of the double walled tube in such manner as to provide substantially equal quantities of fluid at substantially the same velocity in each sub-compartment thereof, and means to azi-34,448

Yexhaust-1 thel uidA fromv the other compartment in; a direction away. from the closed end of;y the double. walled tube in such manner as to pro vide substantially equall quantities of fluid at substantially the same velocity in each subcompartment thereof, said last named means comprising means at a point remote from the joined'l ends of the double walled tube to. form a'. sealt 4between the. outer tube Wall' and the dividing tube, means at a pointv remote from the joined ends. of the double walled tube joined to dividing tube to form a seal between the inner tube wall and the dividing tube, a` manifold` about thev outer tube walll near the. first: sealing means, said manifold being of volute shape and having a, conduit. connected thereto at` the. locationV of maximum cross-section, a: series of equally spaced passages through the outer tube wall Within the manifold communicating with the outer compartment, a, second manifold about the', means joined to the dividingtube, said -manifoldbeing of volute shape and. having a conduitconnected thereto atthe location of maximumcross-sectiom a. series of equally spaced passages through. such meansjoined to. the dividing. tube. within the second manifold com municatingv with the second compartment, and means to introduce. purging gas. into the bore within the innerv wall of the double walledl tube in adirection toward the forward end of the vtube adaptedtobe positioned inside the-furnace.

10. Aiiuid-cooled tube comprising a main body made up.` of* a double Walled; tube. adapted to be mountedso that. its forward. endiprojeotsthrough awall of .a.furnace, said tube having an outer wall and aninner, wall coaxial thereof and spaced radially therefrom', there being anY unobstructed bore.v within. the inner wall-1 off the tube-t0 provide a. line` of sight through the tube means joining the outer andv inner Walls of the tube at. the.; forward. end thereof to. form afluidtight joint an. intermediate dividing tubex to divide the` space between the tubeY walls to separate such space..into..an inner` and:` anoutercompartment,. each extending longitudinally ofthe tube to a point in; the regionof but somewhatspaced from;.the;.juncture of the innervand outer tube wailsiwhere; thecnmpartments join, means sule stantially to divide the innerf andf outer compartments into .axially extending-- sub-compartments... means toedirect cooling fluid into--one-of the, compartments in a direction toward the closed forward end of. the double walledltube-#in such,manner` as: to. providesubstantially equal quantities of duid at substantially thesamelve looity in each subecompartment thereof, means tor exhaust thei fiuid from the other compartment in a direction away from the closed for- Ward. end of the double walled tube insuohinam ner as to providesubstantially equal quantities of fluid at substantially. the: same velocity in each sub-compartment thereof, said last-named meanscomprising. means. generally in. the form off; an tubular extension joinedtoY the dividing tubepattapointremote from the forward end of the; doublexwalled tube-.to form aseal between the.L outer tube wall vand the dividing tube and toiforini a sealbetween the inner tube wall and they dividing tube', said" tubular extension being providedf with. a: flesiblediaphragm= betv een the dividing; tube andiitspoint1of connection to the outer wallof.' the double walled tube andwithra flexible. diaphragm.between the dividing tube and; its pointof: connection tothe inner wall `of theeclouble walled tubeY tor permit. expansion 16 ory contraction of the outer and inner tubewalls relative. to. each other, and. means to introduce purging: gasintothe bore within the inner. wall of the double walled tube ina direction toward the forward end ofl thev tube, said'uid-exhaust means being between. said diaphragms.

ll'. A. fluid-cooledztube comprising a main body made up of a double walled tube adapted tor be mounted, so that its forward end projeotsthrougrh a wall. of a. furnace, said tube having: an outer wall and an` inner wall coaxial thereof and spaced radially therefrom, there being an unobstruotedr bore within. the inner wall of thev tube `to provide a line. of sight through thev tube means joining. the outerv and inner walls of the tube at the forward end thereof to forma fluid tight joint, an intermediate dividing tube to diivide the space between thev tube wallsto sepa',- rate such space into an inner. and an; outer compartment, each extending longitudinally of the tube to a point. inthe region of but somewhat spaced from the juncture of.' the inner and outer tubewalls where the compartments join, means substantially to divide the inner andl outer compartments into axially extending sub-compartments, means to direct cooling fluid into one. of the compartments in a. direction. toward' the closed forwardv end of the double. walled tube in such manner as to provide substantially equal quantities of fluid at substantiallyA the.V same velocit'yy in; eachsub-compartment thereof, means to exhaust the fluid from the. other compartment: in direction away frornther closest for# ward end of the doublewalled tubeiin such man.- ner as to providev substantially equalV quantities of uid atsubstantiall'y the same velocity in each sub-compartment thereof said last namedmeans comprising means generally vin the form of a Arigid tubular extension joined. to the dividing tube at a point remote from the forward end of the double walled tubeY to form a seal between' the outer tube wall and the dividing tube and rig.- idiy joined to the inner tube wall to form a seal between the innerA tube wall and the` dividing tube, the tubular extension having one end in telescopedrelationship.v with the thel rearward endof the outer wall of theidouble Walled tube, a packing means between the tubular extension and the outer wall permitting longitudinal Inovement of.1 theextension relative to the'outer wall to permitexpansion or contraction of theouter and inner-tube walls relative to each other, and meansf to introduce purging gas into theA bore within the,y inner wall of the double walledtube in adireotion toward the v'forward end of the tube.

l2. A fluidecooled tube comprising arl-outer barrel, an inner tubev extending rearwardly through and beyond the'. barrel coaxiallyv thereof from the forward end and` joined therewith continuously around saidv end, a tubular baille extending into the barrel from the rear end thereof between the-barrel and inner tube andY terminating short of the junction thereof,V an inletmanifold surrounding the barrel adjacent the rear end, flanges adjacent the rear ends. of said barrel and tube, flexible diaphragrns exe tending from said. flanges to the end of said 17 entially thereof forming passages therealong of substantially equal sectional area.

14. The tube defined by claim 13 character ized by said ribs being staggered between the manifold ports.

EMIL JANTSCH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Number Name Date Terriault July 8, 1924 Coen Feb. 16, 1926 Tolfree Dec. 19, 1933 Gould Nov. 3, 1936 Bennett Oct. 4, 1938 Dike Feb. 18, 1941 Vollrath Feb. 13, 1945 Gunter Mar. 20, 1945 FOREIGN PATENTS Country Date France Oct. 29, 1930 France May 24, 1939 Sweden Mar. 13, 1937 OTHER REFERENCES L & N Bulletin N33B685 (1939) page 3.