US2981241A

US2981241A - Radiant wall construction for vapor generator

Info

Publication number: US2981241A
Application number: US755063A
Authority: US
Inventors: Francis M Barton
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1958-08-14
Filing date: 1958-08-14
Publication date: 1961-04-25
Anticipated expiration: 1978-04-25

Description

April 25, v1961 F. M. -BARToN RADIANT WALL CONSTRUCTION FOR VAPOR GENERATOR Filed Aug. 14, 1958 3 Sheets-Sheet 1 ATI' RNEY INVENTOR M. BARTON ATTORNEY 3 Sheets-Sheet 2 /n//n//N//ff/ l FRANC/5 April 25, 196i F. M. BAR'roN RADIANT WALL CONSTRUCTION FOR VAPOR GENERATOR Filed Aug. 14, 1958 April 25, 1961 F. M. BARTON 2,981,241

RADIANT WALL CONSTRUCTION FOR VAPOR GENERATOR Filed Aug. 14, 1958 3 Sheets-Sheet 3 lng) I L7 O @WwW-:122% 2@ 7 ATTORNEY RAM-ANT WALL CONSTRUCTION FOR VAPOR GENERATOR Francis M. Barton, St. Albans, NX., assignor to Foster Wheeler Corporation, New York, N.Y., a corporation of New York Filed Aug. 14,- 195s, ser. N0. 755,063 12 Claims. (C1. 122-0' This invention relates to vapor generators and more particul-arly to vapor-cooled walls of Vapor generators.

In vapor-generators having a combination of vaporcooled and liquid-cooled furnace walls or vapor. and liquid-cooled sections in the same furnace wall, the problem of differential expansion and contraction between the abutting vapor-cooled and liquid-cooled walls or the vapor and liquid-cooled wall sections is encountered. Heretofore, this diierential linear expansion and contraction problem has been solved by rather elaborate and relatively complex spring and tie-back larrangements forsecuring vthe tubes -to the furnace wall and seal slip joints for connectingkthe abutting liquid and vapor-cooled walls together whereby relative movement between the walls is permitted. In Vapor generatorswhere a wall comprises a combination of liquid and vapor-cooled sections, the wall has been provided with costly fluid seal slip joints between the abutting steam and watercooled wall sections.

for connecting and supporting vapor and liquid-cooled walls or wall sectionsof a vapor generator to allow for differential linear expansion of the abutting walls or wall sections is that skin or skinand iin-tube type casings cannot'be employed. A skin casing as used hereinrelates to acasing wherein the metal sheets or sections ofthe casing are disposed relatively close to theuid conducting tubular members of the vapor generator walls and with little or nol insulating refractory material between the tubular members and thecasing so Athat thecasing sections are at a temperatureclosely approximatingthe temperature of the tubularmembers. A casing of conventional type'is insulated from the tluid conducting memi walls and pressure parts of the vapor generator, v.and where the vapor generator had to be provided with separate buckstay systems 'for the Vapgor-cooledbtubesI and.' liquid-cooled tubes, thus resultingin arelativelyc'omplex and costly vapor generator structure.

Accordingly, .itis an, object of the present invention' to provide in a vapor "generator a novel vapor-cooled furnace wall which obviates the necessity for elaborate.,65

spring and tie-back assemblies orspecial sealing varrangements and/or other specialme'ans for allowing for differcooled walls and liquid-cooled furnace walls'.t r"

. Anotherobject of this invention is to all furnace walls.

One Of the disadvantages of the aforementioned means 35 provide inria vapor" generator a Vapor-cooled furnace Wall wherein a single 1 A further object of the present invention is to provide in a vapor generator a novel vapor-cooled wall in combination with liquid-cooled walls which permits the .use of skin or skin and iin-tube typecasing's.

.The present invention contemplates a vapor-cooled wall, that is, a wall comprising Vapor-cooled tubes or a-combination of vapor-cooled and liquidecooled tube bank sections, in which -thevapor-cooled tubes are' provided with at least one expansionbend or loop portion disposed between means for xedly securing the tubes against movementrelative to liquid-cooled tubes so that of the vapor-cooled tubes.

differential linearexpan'sion or contraction' vaporcooled wall or section andthe abutting liquid-v cooled walls or sections is compensated for pansion bends of the vapor-cooled tubes` In av lirst embodiment of the present inventiona vapor-` cooled furnace wall in combination with abutting liquidcooledwalls is disclosed wherein the vapor-cooled wall comprises a plurality of vapor-cooled tubes disposed in parallel relationship witheach other. The vapor-cooled tubes are arranged-in groups with la plurality of tubes in each group. Each tube of each group of tubes, at a point between .the opposite ends of the tubes, is provided with at least one expansion loop tions Of each tube of a group'of tubes are dimensioned so that a loop portion of one tube lies within the loop portion of anext adjacent tube of the group of tubes. The vapor-cooled tubes adjacent their loop portions are so formed that the loopportions of each group of tubes lies in a plane adjacent the plane of the straight portions The loop portions `of the tubes of a group of tubes is offset from the loop portions of a Anext adjacent group of tubes so that the loop portions of one group of tubes is disposed in a plane adjacent the kplane. of the straight portions of the next adjacent group of tubes. Means are provided for securing each of the vapor-cooled 'tubes at the apex of the loop portion against movement relative to the liquid-cooledf provided for supporting vand I. may also secure and support the liquid-cooled tubes.-

. Ina `second embodiment of this .invention a vaporcooled wall is disclosed 'which consists of at least "one bank, of vapor-cooled,tubes disposed adjacent at nleast one bankof liquid-cooled tubes. The vapor-cooled tubes are arranged in parallel relationship with 'each other and i theliquid-cooled tubes;

ranged .in twofdr'morelgroups with each vtube lof eachf group proyided with: at least one expansion bend or loop `portion `disp sed vbetween the oppositef'ends of the The loop portion-s of the tubes in e'a'cfhgrou'pj` of casingV which had to be supported independently ofnthe` if tubes'.

The vapor-cooled tubes vare lvar tubes' are :dimensioned so that a loopjportion of one portions ofV Agroup lies fthe loop tube in the'group'.) The tubes rof eaeh'group of tubes' are so formed adjacent the Yloop The loop` portions vofo'ne'A group of vapor-cooled tubes soifset from the loopfportions of another group of tubes so that thev loop adjacentgroup of tubes. `Means are provided for securloop portion lagainst movement from opposite'fsidesV offthewloop poltions -against move` Patented Apr. 25, 1961` between ,the

portion. The loop por-` group of tubes oneach side.

portion vof a'next adjacent r Y portionsl that: the loop v A l y of tubes ylies in 'aplane adjacenfto the plane of thestraight portionsy of the vapor-cooled tubes,

A A portipns of the vaporcooled tubes of one group lies underrthe straightportions 'of the` ential linear expansion or contraction betweenvapor` ment relative to the liquid-cooled tubes whereby differential linear expansion or contr-action between the vaporcooled tubes and the lliquid-cooled tubes is compensated for by the loop portions of the vapor-cooled tubes. Said first and second means may be also employed to secure and support the liquid-cooled tubes.

In the aforedescribed embodiments, the vapor-cooled Walls are provided with a layer of heat insulating refractory material disposed adjacent the tubes, with a skin casing portion disposed to cover the outersurface of the layer of heat insulating refractory material. The thickness of the layer of heat insulating refractory material is determined by that amount of insulation which is necessary to maintain the skin casing section adjacent the vapor-cooled tubes at substantially the same temperature as the skin casing section adjacent the liquid-cooled tubes. It is also contemplated that a layer of heat insulating refractory material may be provided between the liquidcooled tubes and the casing section adjacent thereto, in which instance, the layer of refractory material adjacent the vapor-cooled tubes would be thicker than where no heat insulating refractory material is provided adjacent the liquid-cooled tubes. A skin or a skin and iin-tube type casing is feasible since expansion and contraction of the vapor-cooled wall or section is that of the liquidcooled wall or section and the differential linear expansion or contraction between the vapor-cooled tubes and the liquid-cooled tubes is compensated for by the compression or expansion of the ,loop portions of the vapor-cooled tubes. f

The invention will be more fully understood from the following detailed description thereof when considered in connection with the accompanying drawings wherein two embodiments of the invention are illustrated by way of example, and in which:

Fig. l is a fragmentary view in section of a vapor generator having a vapor-cooled wall according to a rst embodiment of this invention;

Fig. 2 is a sectional View taken along line 2-2 of Fig. l;

Fig. 3 is an enlarged fragmentary view in perspective of the vapor-cooled tubes and the means for securing them to a channel buckstay;

Fig. 4 is a fragmentary view of the corner construction between the vapor-cooled wall and an abutting watercooled wall; j

Fig. 5 is a fragmentary view in section of a vapor generator furnace having. a vapor-cooled wall according to. a second embodiment of this invention;

Fig. 6 is a sectional view taken along Fig. 5;

Fig. 7 is a view, in section, taken substantially along line 7-7 of Fig. 5; and

Fig. 8 is a sectional view taken substantially along line 8-8 of Fig. 5.

`Referring now to the drawings nd `more particularly to Figs. l, 2, 3 and 4, the reference numeral 10 designates a kvapor-cooled -wall whichflabutsy lopposiltely disposed liquid-cooled

walls

11 and 12. ,Vapor-cooled wa-ll defines with walls 11 land 12,` and another. liquidcooled wall (not shown) a furnace chamberf`13 of a vapor generator. Vapor-cooled Wall `1 0 .comprises a layer of heat insulating refractory material 14 anda bank of ,verticallyfextendingk tubular members' 15 which are disposed adjacentl to. the innersurfaceof the layer-of heat insulining refractory materialV 14. Tubular members 15 areA arranged vin `parallel v relationship withonefanother land.

are connected at one end to a'sourceof vapor, suchas a header (not shown), to receive vapor, as for example,

such as a header (not shown), to Yreceiveva'p'or,y asmfor/A example, steam orsteam'to be reheated, and passithe'4 vapor in indirect` heat exchange relationship with p rodf ucts of combustion in chamber 13 to heat saidvapOr. Tubular members 15 are connected attheiroppositeadjacent ends' to a vapor receiver (not shown), .such as, an outlet header, to pass heated vaporthereto. Twoverrality of adjacent tubular members.

tween channel buckstays buckstays 17 and '2.5.

.of U-bend portion 21 within recess 20 and in a plane offset Ifrom the plane of lar members 15so that the line '6 6 of which'are connected in a tically spaced horizontally extending channel buckstays 16 and 17 are disposed against the oulter surface of refractory layer 14. Each of the tubular members 15 is secured to channel buckstays 16 and 17 by plate members 18 and 19, respectively, the tubular members 15 being secured, as by welding, to the inner edges of said plate members 1S and 19 while the opposite outer edges of plate members 18 and 19 are secured, as by welding, to the respective channel buckstays 16 and 17. A recess 2t) is provided in the inner surface of heat insulating refractory layer 14 at a point substantially midway between channel buckstays 16 and 17, the purpose of recess 20 will be hereinafter described. The lower edge Z0-A of recess 2t) is downwardly inclined so that slag ily ash and soot will ow from the recess back in furnace chamber 13 and will not be trapped therein.

The banks of tubular members 15 are divided into a plurality of groups with each group comprising a plu- The number of groups of tubular members and the number of tubular members in each group is dependent upon the size of vapor-cooled wall 10, size of the tubular members and other factors relative to a particular vapor generator design. However,` for illustration purposes vapor-cooled wall 10 is divided into eight groups with three tubular members in each group, but only four groups are shown -for reasons of clarity and because the arrangement of the tubular members for one half of wall 10 is identical with the tubular arrangement of the other half. Also for illustration purposes tubular members 15 are shown in close spaced relationship with each other while in actual prac-- tice the tubular members may be arranged intangential abutment with each other.

As best shown in Figs. l, 2 and 3, each tubular member 15 in each group has a horizontally extending expansion loop or U-bend portion 21 and is provided with a pair of compound bends Z2 and 23 at the ends of the legs whereby U-bend portion 21 lies the straight portions of tubular members 15. U-bend portion 21 of each tubular member of a group of tubular members is dimensioned so that a U-bend portion 21 of one tubular member is nested within the U-bend portion 21 of the next adjacent'tubular member 15 of the group. As shown, the nested U-bend portions 21 of one group of tubular members 15 arranged, with respect to Vthe nested U-bend portions nested U-bend portions 21 of onel group lie under or behind the straight'portions of ltubular members 15 of the next adjacent group of tubular members 15. j

' As shown, another

tally extending channel'buckstays

24 and 25 are positioned against the outer surface of refractory layer 14 and adjacent tolthe U-bend portions 21 of tubular members 15. `Tubular members 15 in, each group of tubular members are secured at the apices of their U-bend'- portions 21 to channel buckstays 24 and 25 by plate '

members

26 and 27.

Plate members

26 and 27 are secured along one edge,'fas by Welding, to channel buckstays" 24 and 25, respectively, and are secured, as by welding, to tubular members 15 along their opposite edges (seek Fig.y v 'llubular members. 15'y are slidably supported in a suitable'manner (not shown) Well known by those skilled in the art, as for example,"by movable tie-bars', to one or more horizontal buc stays-(not shown) disposed bev 16` and 24 and between channel Vapor-cooled .wall 1(lV is provided withv a skin-type casing 29 which is"disposed against the outer'surface of heat "insulatingy refractory'layer 14; As best shown'in Fig. 2, casing`29 fluid-tight manner, as'by welding, -to channelbuckstays 21 of an adjacent group of tubu- 'pair of vertically spacedfl'lorizon` mayy comprisefa plurality 'of sections is, 17,24 and 25 and the um: nel buck'stays' (not shown)` disposed between channel 5.

buckstays

16 and 24, -17 and 25. Adjacent the outer surface of casing 29 is disposed a layer of insulating material 30 and an outer sheathing 31 of metal or hard finish cement. Heat insulating refractory layer '14. and heat insulating layer 30 may comprise a plurality of t5V blocks or may be castable insulating material.

Liquid-cooled wall 11 comprises a bank of vertically extending liquid-cooled tubular members 32 which are arranged in parallel relationship with each other and may be disposed in tangential abutment with each other, although, for illustration purposes the tubular members are sho'wn in close-spaced relationship. Each of the tubular members 32 is connected at one end to a source of liquid (not shown), as for example, an inlet header to receive liquid, such as water, from said inlet header and passes 15 the liquid lin indirect heat exchange relationshipwith combustion products in furnace chamber 13 to vaporize at least part of the liquid in said tubular members 32. The opposite end of each of the tubular members 32 is connected to a receiver of vapor and/or vapor-liquid mixture (notshown), as for example, an outlet header, to pass vapor and/or vapor-liquid mixture, such as steam and/ or steam and water into said outlet header` Tubular members 32 are lixedly secured to and supported by horizontally extending

channel buckstays

33, 34, 35 and 36 25 which are disposed to lie in the same horizontal planes as the

respective channel buckstays

16, 24, -,and 17. Each of the tubular members 32 are also iixedly secured as by welding, to one or more horizontal channelbuckstays (not shown) disposed between channel buckstays 33 and 34 and between channel buckstays 35 and 36. Liquid-cooled wall 11 is provided with a skin casing 37 comprising a plurality of sections lwhich are secured in a duid-tight manner, as by welding, to channel

buckstays

33, 34, 35 and 36 and the aforementioned channel buck- 35 stays (not shown) disposed between the latter. A layer of heat insulating material 3S is disposed adjacent the outer 'surface of skin casing 37 as well as an outer sheathing 39 of metal or hard finish cement disposed to cover the surface of heat insulating material 38.

Liquid-cooled wall 11, as well as the liquid-cooled Wall (not shown) disposed opposite vapor-cooled wall 10, are` identical in construction and, therefore, will not be described in detail. Accordingly, parts of wall 12 corresponding to like parts of wall 11 will be designated by 45 the same reference numeral, but with the suffix A added thereto.

Channel buckstays

16, 17, 24 and 25 of vapor-cooled wall 10 are respectively secured at one end to channel

buckstays

33, 34, 35 and 36 of liquid-cooled wall 11 50 (Fig. 4) and at their opposite ends are respectively se-v cured to channel

buckstays

33A, 34A, 35A and 36A of liquid-cooled wall 12. Skin casing 29 of Iwall 10 is connected in a fluid-tight manner, as by welding, to skin v casing 37 of wall 11 and' skin casing 37A of wall 12. y 55 In the same manner aforedescribed, channelI buckstays of 4the liquid-cooled wall (not shown) are secured to the ends of

channel buckstays

33, 34, 35 and 36 ofwall 11 and

channel buckstays

33A, 34A, 35A and 36A of wall 12, thereby providing 'a channel buckstay system 60 which is common to all the Walls of the vapor generator. The casing of the liquid-cooled wall, not shown, is secured in a duid-tight manner to

casings

37 and 37A of

walls

11 and 12, respectively. The heat insulating material 30, 38and 38A of the

respective walls

10, 11 and 65 1 2, including

sheathing

31, 39 and 39A of the walls, as well as the lheat insulating material and sheathing of the` liquid-cooled wall, not shown, a-re integrally joined to gether to form a unitary vwall structure detining charnber 13.

As vcan be seen from the'foregoing description, the longitudinal expansion of tubular membersv 15 of vaporcooled wall 1t) between channel 'buckstays 16 and 17, which llinear expansion'. is greater than the longitudinal or linearexpansion of tubularmembersv 32 and 32A'of el Walls 11 land 12, including the liquid-cooled tubular members ofthe wall, not shown, will cause the legs of U-bend portions 21 of tubular members 15 to be compressed toward each other. Accordingly, the U-bend portions 21 of tubular members 1S are dimensioned so that the distance between the legs of the innermost U-bend portion 21 of each group of` nested U-bend portions is at least equal to the calculated maximum differential expansion between the vapor-cooled wall 10 and the liquid-cooled walls of the vapor generator. If in a particular vapor generator design the calculated m-aximum differential longitudinal expansion between the' Vapor-cooled walls and liquid-cooled walls is greater than the exure stress which may be safely imposed at the U-bend portions A21, it is wi-thin the contemplation of the present invention to provide tubular members' 15 -with one or more additional U-bend portions. For example, tubular member 15 may be lxedly secured to another channel buckstay spaced from channel buckstays A16 or 17 and provided "with nested U-bend portions arranged asheretofore described;

and shown. The U-bend portions are disposed to extend within another recess formed in heat insulating refractory layer 14, which recess is disposed substantially midway between the aforementioned channel buckstay and channel buckstays 16 or 17. 'The kU-bend portions are `se- .cured in the same manner as heretofore described, to two additional channel buckst-ayspsimilar to'channel buckstays 24 and 25. ltln this manner, 'the total calculated i dilferential linear expansion between the vapor-cooled wall and the liquid-cooled walls is divided between theY two U-bend portions in each of 'the vapor-cooled tubular members 15 so that the total ilexure of tubular members 15, at any U-bend is lwithin allowable limits of stress;

The thickness of the layer of heat insulating refractory material 14 is determined by that amount of insulation necess-ary to maintain skin casing 29 'of vapor-cooled wall 1-0 at substantially the same temperature' as

s'kin casing

37 and 37A of liquid-cooled walls 11 and 12 'so that no differential expansion between casing 29 'and the skin 0 casings of the liquid-cooled lwalls exists, which differ.

ential expansion would cause buckling and/or fracture of the skin casings. The present invention also contemplates a construction whereina layer of heat insulating' refractory materialvis disposed between the skin casings of the liquid-cooled walls and the liquid-cooled 'tubular members associated with the walls.

layer 14 of vapor-,cooled wall 10 `would` be greater than illustrated in the drawings/to maintain the skin casing of the vapor-cooled Wall atsubstantial temperature as the casing adjacentV the liquid-cooled tubes.

' In Figures 5, 6,` 7 and 8, a second .embodiment of the? present 'invention isshown (wherein a vapordcooled wall 4 40 of a vapor generatorcomprises one or more banks 'of vapor-cooled tubular members and one ormore banks of liquid-cooledtubular members. As. shown' in Pigs.

5, 6 and 7, vapor-cooled wall 40 comprises a bank of vapor-cooled tubular members 41 disposed betweenf'a bank of liquid-cooled tubular members 42 and abank V horizontally extendingchannel buckstays v44 andl 45,

simil-ar to channel buckstays 16 and 17 by plates,` 46. Plates 46 are welded, or otherwise suitably secured, to

channel buckstays

44 and 45 along one edge'while tubul y lar members 41 are secured, as byfwelding, to the opposite edge of plates 46. The U-bend portions'47. of each group of tubular members 41, similar to: U-bend portions 21 of eachgroupgof tubu-larmembers 15,V are secured at their apices to two spaced;

channel buckstays

48 and ,49,` similar to; buckstays24 and 25 of-vaporcooledfwall r 10, i by means 0f platesfsfsimilar tcfplates 2.1- r. ,Bl-ares ,5.0,

are'secured along one edge, as by welding, to channel r In thisv latterconstruction, the thickness of .the heat insulating-refractory.'

buckstays

48 and 49, while tubular members 41 are secured, as by welding, to the opposite edge of plates 50 (see Fig. 7). `As best shown in Fig. 8, channel buckstays 4S and 49 extend in a plane parallel with the plane of liquid-cooled

tubular member

42 and 43 to a point adjacent the U-berid portions 47 of vapor-cooled tubular members 41',`at which point `channel buckstays 48 and 49 extend away from the plane of liquid-cooled

tubular members

42 and 43 and thence in a plane parallel to the plane of

tubular members

42 and 43 to thereby provide space for a recess 51 lin a heat insulating refractory layer 52 which forms a part of vapor-cooled wall 40. The lower edge of recess 51 is downwardly inclined to permit slag, y ash and soot to flow` from recess 51. U-bend portions 47 of tubular members 41 extend within recess 51, in the same manner as U-bend portions 21 of tubular members 15 extend within recess 20 in heat insulating refractory layerf14 of vapor-cooled wall 10. v

A skin casing 53 is disposed against' the outer surface of heat insulating refractory layer 52, which casing 53 comprises a plurality of sections suitablysecured in a Huid-tight manner, as by welding, to channel buekstays 44, 45, 43 and 49, in the same manner asthe casing sectionsof s'kin casing 29 of wall 1li are secured to channel

buckstays

16, 17, 24 and 25 (see Fig. 6).

Tubular members 41 are slidably secured in a suitable manner (not shown) as by movable tie-bars,'to one or more channel buckstays (not shown) disposed between channel buckstays 44 and 48 and between channel buckstays 45 and 49. Liquid-cooled

tubular members

42 and 43 are ixedly secured,as by welding, to the forementioned one or more channel buckstays (not shown), disposed between

channel buckstays

44,45, 48 and 49.

As shown in Pigs. 6 and 7, heat insulating refractory layer 52 extends between casing S3 and liquid-cooled

tubrular members

42 and 43. The thickness of refractory layer 52, adjacent liquid-cooled

tubular members

42 and 43, is less than its thickness adjacent vapor-cooled vtubular` members 41 so that the necessary amount of heat insula-` tion is provided to maintain the sections of casing 53 adjacent vapor-cooled tubular members 41 at substantially the same temperature as the casing sections adjacent liquidcooled

tubular members

42 and 43. Vapor-cooled wall 4G, adjacent the outer surface of casing 53, is provided witha heat insulating layer 54 which is covered by a sheathing 55 Aof hard finishv cement or metal. vHeat insulating layer 54 adjacent the vapor-cooled and liquid tubular members is substantially uniform inkthickness. n

Liquid-'cooled tubular members 42 and 4? are secured to and supported by

channel buekstays

44, 45, 46 and 47 and one or more additional channel buckstays, not shown, by means of `plates 56. Each of the plates v56 are welded along one edge to the aforementioned channel buckstays` and are welded to tubular members '42 and 43V along the opposite edge., ,'Inlhe second embodiment hereindescribed, theditfererrtial,` linear' expansion between vvapor-cooled tubularA members 41 and liquid-cooled

tubular members

42 and 43 causes the Ilegsof U-bend portions 47 of tubular members 4110 be compressed together so that expansion of vaporcooled section of vapor-cooled wall 40 is that ofthe liquid-cooled

tubular members

42 and 43, thus permitting the use of a skin casing and eliminating lthe need forcomplicatedwand expensive slip jointconnections between the vapor-cooled section; and the liquid-cooled lsections of Wall U i y Y Vapor-cooled wall 40, herein described, is integrally connected, to abutting liquid-cooled walls which, with vapor-cooled wall 40', denes a`v furnaceA chamber of a vapor generator;V V- Y' l 'It isV contemplated in the present-"invention that instead of a skin'zcasing adjacent liquid-cooled tubular members,

the liquidfco'oledl tubularfmemberslr'nay be provided withv longitudinally extending finsV which arefwelded to trrefneixt` adjacent tubular member to thereby form a fin-tube type casing.

The present invention hasy application to a platen in a furnace chamber, which platen comprises vapor-cooled tubular members or a combination of vapor-cooled and liquid-cooled tubular members. In such application, iin or iin-tube type casings and layers of heat insulating refractory material, shown in the drawing are unnecessary. Any suitable means, other than channel buckstays, may be employed to secure the vapor-cooled tubes, at the U-bend portions vand at points spaced on either side of the U- bend portions, against movement relative to the liquidcooled tubes of the vapor geneartor. A platen constructed according to Vthis invention eliminates the requirement for special support members to allow for differential expension as in conventional platen structures.

From the foregoing description, a vapor-cooled wall for avapor generator has been provided wherein differential linear'expansion betweenthe vapor-cooled tubes and the liquid-cooled tubes is effectively absorbed by the novel4 vapor-cooled tube form and arrangement thereby making skin and skin and fin-tube types of casings feasible. The vapor-cooled walls" according to this invention obviates the necessity for complicated slip joints between vapor-cooled and liquid-cooled walls or wall sections. The invention also provides a vapor generator having a vapor-cooled wallwherein the tubular member support system is cornmonto all the walls of the vapor generator.

Although but two embodiments of the invention have been illustrated and described in detail, it is to be eX- pressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art.

What is claimed is:

l. In a vapor generator having at least one vapor-l cooled wall in combination with liquid-cooled walls, the vapor-cooled wall comprising at least one bank of vaporcooled tubular members with the said tubular members thereof being arranged in parallel relationship Ato each other, each of said vapor-cooled tubular members having at least one loop portion disposed betweenthe opposite ends of the tubular members, means for xedly securing each of said tubular members at the loop portion against `movement relative to said liquid-cooled walls, second means for fixedly securing eachof said vapor-cooled tubular mem-bers at each side of the loop portion thereof against movement relative to said liquid-cooled walls whereby diiferential linear expansion between the vaporcooled tubular members and the liquid-cooledvwalls compresses said loop portions of the vapor-cooled tubular members an amount equal Vto said diterential linear expansion.

2. In vthe furnace of a vapor generator having at least one vapor-cooled wall `in combination "with liquid-cooled walls, the`vapor-cooled wall comprising at least one bank of vapor-'cooled ltubes disposed in parallel relationship to each other, each of said vapor-cooled tubes having at least onetintegral UJbend portion disposed between the opposite ends of the tubes, means for xedly securing eachof said 'tubes at said U-bend portion against movement relative to said Vliquid-cooled walls, and second means lfor, Xedly securing eachof' saidtubes at each sidev of said U-bend portion against movement relative tosaid liquid-cooled walls whereby differential linear expension or contraction between the lvapor-cooled tubes is taken up 'by `the U-bend portions, the spacing between the legs of said U-bend portions being of a dimension at least equal to the-predetermined maximum differential expansion `-between the vapor-cooled tubes and liquidcooled walls.

B ln the furnace `ofa vapor generator having at least one Vvapor-cooled wall in combination with liquid-co'oied walls, the vapor-'cooled wall comprising at 'least one bank to each other, each of said liquid-cooled walls whereby differential linear expansion or contraction between the vapor-cooled tubes and the liquid-cooled walls is taken up by the expansion or contraction of the loop portions. Y

4. In the furnace of a vapor generator having liquidcooled and at least one vapor-cooled wall, the vaporcooled wall comprising, a wall layer of heat insulating material, at least one bank of vapor-cooled tubular members disposed to extend parallel to said wall layer, said tubular members being arranged parallel to eachother, each of said vapor-cooled tubular members being provided rwith at least one U-bend portion disposed between the opposite ends of the tubular members and extending normal to the longitudinal axes of the tubular members, means for xedly securing and supporting each of said tubular members against movement at the apex of the U-bend portion of t-he tubular members, second means for iixedly securing and supporting each of said vaporcooled tubular members against movement on each side of the U-bend portions whereby linear expansion of the vapor-cooled tubular members in excess of the linear expansion of the liquid-cooled walls compresses said U-bend portions.

5. The apparatus of claim 4 wherein the U-bend portions of each of the tubular members is dimensioned so that a U-bend portion of one tubular member lies within the U-,bend portion of the adjacent tubular member.

6. In the furnace of a vapor generator having at least one vapor-cooled wall in combination with liquid-cooled walls, the vapor-cooled wall comprising a wall layer of heat insulating refractory material, at least one bank of vapor-cooled tubes disposed to extend vertically and parallel to said wall layer and with said tubes being arranged in parallel relationship to each other, each of said tubes being provided with at least one U-bend portion disposed between the opposite ends of the tubes and extending normal to the longitudinal axes of the tubes, means for xedly securing and supporting each of said tubes at said U-bend portions against movement relative to said liquid-cooled walls, second means for xedly securing each of said tubes at points spaced on either side of said U-bend portion against movement relartive to said liquid-cooled walls, the spacing between the legs of said U-bend portion of each of the vapor-cooled tubes being of a dimension at least equal to the predetermined difrerential expansion between the vapor-cooled tubes and liquid-cooled walls. n

7. In the furnace of a vapor generator having at least one vapor-cooled wall in combination with liquid-cooled walls, the vapor-cooled wall comprising a bank of vaporcooled tubes disposed to extend vertically with the tubes being arranged in parallel relationship to each other, said bank of vapor-cooled tubes being divided into a iirst and second group of steam-cooled tubes, each tube of said first group of tubes being provided with at least one U-bend portion disposed between the opposite ends of the tubes and extending normal to the longitudinal axes of the tubes, said lU-bend portions of each of the tubes of said first group of tubes being dimensioned so that a U- bend portion of one tube lies within the U-bend portion of the adjacent tube, each tube of said second group of tubes being provided withat least one U-bend portion disposed adjacent the U-bend portions of said iii-st group of tubes, said U-bend portions lof each of the tubes of said second group of tubes being dimensioned so that a Y 10 U-bend portion of one tube lies within the U-bend portion of the adjacent tube, said U-bend portions of the tubes of said rst and second group of tubes being offset from each other and disposed to extend in a plane parallel to the. plane of the straight portions of the tubes of the other group of tubes, means for securing and supporting the tubes of said trst and second groups of tubes at their respective U-bend portions against movementV relative to the liquid-cooled walls, second means for securing the tubes of said rst and second group of tubes at spaced points on either side of the U-bend portions against movement relative to the liquid-cooled walls, the space between 'the legs of the innermost U-bend of the tubes in the rst and second group of tubes being of a dimension at least equal to the calculated differential linear expansion between the vapor-cooled tubes and the liquid-cooled walls.

8. In the furnace of a vapor generator having at least one steam-cooled wall in combination with Water-cooled walls, the steam-cooled wall comprising a wall layer of heat insulating refractory material, said wall layer being secured to adjacent `Water-cooled walls, a bank of tubes disposed to extend vertically and parallel to said Wall layer with the tubes arranged in parallel relationship with each other, said bank'of steam-cooled tubes being divided into a plurality of groups of steam-cooled tubes, each tube of each group of tubes at least one U-bend portion disposed between the opposite ends of the tubes and extending normal to the longitudinal axes of the tubes, said U-bend portions of the tubes of each group of tubes being dimensioned so that a U-bend portion of one tube lies within the U-bend portion of the adjacent tube, a recess in the surface of said wall layer to provide a space between the straight portions of the tubes and the wall layer, the steam-cooled tubes being so formed that the U-bend portions thereof in each group of tubes vlie within said recess between the surface of the recess and the straight portions of the next adjacent groups of tubes, means for securing and supporting the tubes of each group of tubes-at the -apex of their respective U-bend portions against movement relative to said water-cooled wall, and second means for securing and supporting the tubes of each group of tubes at points spaced from each side of their respective U-bend portions against movement relative to said water-cooled wall, the space between the legs of the innermost U-bend portion of each group of tubes being of a dimension substantially equal tothe calculated maximum diiferential liner expansion between the steamcooled tubes and the water-cooled Walls.

9. The apparatus of claim 8 wherein a skin type casing is provided on the vapor-cooled and water-cooled walls.

10. Ina furnace of a fluid heater, a vapor-cooled wall comprising atleast one bank of vapor-cooled tubes and at -least one bank of liquid-cooled tubes, said liquidcooled and vapor-cooled tubes being arranged in parallel relationship to each other, said bank of vapor-cooled tubes being divided into at least two groups of vaporcooled tubes, the tubes of each group of tubes being provided with at least one U-bend portion extending normal to the longitudinal axes of the vapor-cooled tubes, said U-bend portion of each tube in a group of tubes being dimensioned'so that a U-bend portion of one tube lies Within the U-bend portion of 'the next vadjacent tubev of the group of tubes, the tubes of each group of tubes being formed so that the U-bend portions of a group of vapor-cooled tubes lie in a plane adjacent to the plane of the straight portions of the vapor-cooled tubes, means for securing and supporting the liquid-cooled tubes, second means for-.securing thevapor-cooled tubes on each side of the U-bendv portions of the vapor-cooled tubes `against movement relative to said liquid-cooled tubes, and third means for securing the vapor cooled tubes at the U-bend portions against movement relative to the liquidcooled tubes whereby differential linearA expansion bebeing provided with tween the vapor-cooled tubes and liquid cooled tubes is taken up by compression of the U-bend portions of the vapor-cooled tubes.

11. In the furnace of a vapor generator having at least one vapor-cooled wall in combination with liquid-cooled walls, the vapor-cooled wall comprising a wall layer of heat insulating refractory material connected to the adjacent liquid-cooled walls, at least one bank of vaporcooled tubes and at least one bank ot liquid-cooled tubes disposed adjacent said wall layer, said liquid-cooled and vapor-cooled tubes being arranged in parallel relationship to each other, said bank of vapor-cooled tubes being divided into at least two groups with a plurality ot tubes in each group, the tubes of each group of tubes being provided with at least one'U-bend portion extending normal to the longitudinal axes of the tubes, said U-bend portion of each vapor-cooled tube in each group being dimensioned so that a U-bend portion of one tube lies within the U- bend portion of the next adjacent tube of the group of tubes, the tubes'of each group of tubes being formed so the U-bend portions of ya group of tubes lie in a plane between the surface of the wall layer and the straight portions of the tubes of the adjacent group of vapor-cooled tubes, means for securing and supporting the liquidcooled tubes, second means for securing and supporting the vapor-cooled tubes of each group on each side of the U-bend portions of the vapor-cooled tubes, and third means for securing and supporting the vapor-cooled tubes at the U-bend portions against movement relative to said liquid-cooled tubesr whereby diierential linear expansion between'the vapor-cooled tubes and liquid-cooled tubes is taken up by the compression of the U-bend portions of the vapor-cooled tubes.

12. The structure of claim 1l wherein said wall layer is provided with a recess in the inner surface thereof disposed adjacent the U-bend portions of said vaporcooled tubes and adapted to receive said U`bend portions therein.

References Cited in the tile of this patent UNITED STATES PATENTS 524,391 Mosher Aug. 14, 1894 2,243,430 Lacke May 27, 1941 2,312,876 Caldwell et al. Mar. 2, 1943 2,477,950 Bailey s Aug. 2, 1949 OTHER REFERENCES Y 625,661 Germany -2 Feb. 13, 1936 UNTED STATES PATENT OFFICE CERTIFICATE OF CRRECTION Patente Ne. 2,981,241 April 25, 1961 A Francis M. Barton I 1b 1e bereby Certified bbeb errer eppeere in Jebe ebeve numbered pebe111'J requiring correction and that the said Letters Patent. should read as `corrected below.

Column 3, lines 69 and 70, strike out "such as a header (not shown) to receive vapor, as for example,"; column 7, line 5, for "member" read members line 33, for "44, 45, 48 and 49" read 44, 48, 45 and 49 column 8, line 13, for "genear or." read generator column lO, line 39, for "groups" read group Signed and sealed this 21st day of November 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC