Патент USA US2047907код для вставки
July 14, 1936. K. NAPIER ' 2,047,907 FLUID HEAT EXCHANGE APPARATUS Filed May 4, 1953 3 Sheets-Sheet l mm“; I ml )\ Pinning? "m 31mg!!!I Z1 Z2 INVENTOR JQHTIEtiZ Nc-zpz'er ‘ ' ATTORNEY July 14, 1936. K. NAPIER 2,047,907 FLUID HEAT EXCHANGE APPARATUS Filed May 4, 1933 3 Sheets-Sheet 2 INVENTOR ATTORNEY July 14, 1936. K. NAP|ER ' 2,047,907 FLUID HEAT EXCHANGE APPARATUS Filed May 4, 1933 3 Sheets-Sheet 3‘ INVENTOR Kenneth Mpz'er BYEFRR~KM ‘ ATTORNEY 2,047,907 Patented July 14, 1936 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE APPARATUS Kenneth Napier, Barberton, Ohio, assignor to The Babcock & Wilcox Company, Newark, N. J., a corporation of New Jersey ' Application .May 4, 1933, Serial No. 669,285 . 49 Claims. by the addition of packing material inserted be This invention relates to furnace wall con struction used in ?uid heatexchange apparatus. tween. adjacent blocks or between adjacent tubes One object of the invention is'the provision of oraby- plastic insulation applied to the outside of blocks which may be used in a continuous series the structure. In order that the wall blocks may be placed in '5 to close the spaces between ?uid conducting tubes the furnace walls or the rows of tubes as indi Another object is the provision of such blocks in a form which will permit them to be placed in position along a furnace wall by insertion I0‘ between the support members or water tubes from without the furnace. cated in Figs. 8, 9.and 10, they are formed as hereinafter described. The inner‘ end 24- of each block is of such a dimension. that it may be m- 10" sertedbetween two adjacent tubes in when the block. is turned to the position indicated in the left hand part. of Fig. 8' of the drawings. In this ' ' A further object is the provision of means for mounting block units to produce pressure be } tween the parts forming the unit and the tubes 155 in order to hold the block units ?rmly in place, and yet permit the removal of blocks when it is desired to» replace them without requiring dis turbance of the entire wall or even adjacent units. Other object will appear upon considera 20- tion of the present speci?cation. 1 In the accompanying drawings: . > ' Fig. 1 is a side elevation of a portion of a _ l furnace wall embodying the invention, Fig. 2 is a front elevation of the wall illustrated 25 in Fig. 1 viewed from the inside of the furnace. ‘ Fig. 3 is a section on the line III-III of Fig. 2-, Fig. 4 is a. rear view in elevation of a portion. of the wall shown in Fig. 2, Fig. 5 illustrates the invention applied to tubes ' spect to the furnace interior, I Fig. 6 illustrates the invention applied: to» tubes which are curved in a convex sense with respect to the furnace interior, ‘ 35 > Fig. 7" is a perspective view of one of the wall; ' > Fig. 8 is a detail view showing successive steps in the formation of the furnace wall built ac‘ cording to the present invention, " v 45‘ ' Fig. 9 is a detail elevation showing two ‘wall block parts in an intermediate position, and-—' I‘Fi'g'. 10- is a detail front elevation of a wall section. _‘ V ‘ v position the block is substantially 90° removed fromits operative position in which it forms a 15 part of the completed furnace wall. After the inner end of the block is passed beyond the center line of two‘ adjacent tubes as indicated in the intermediate part of Fig. 8, the block is turned tolthe position indicated at the right hand 20‘ partof that ?gure. Further turning of the block brings it to-the position in. which it is indicated in Fig. 9 of the drawings. After two complementary blocks are brought into position as indicated in Fig. 9. of the draw- 25v ings, a tension member I6 is passed through cor responding openings l8< in the heel or outer por tion. 20 of each element, andla resilient member 2i‘. .Thereafter a nut 22 tightened on the ten sion member l6 against the member 2i brings the 30 30' which‘ are curved in a concave sense with re blocks, 5 their operative. positions from points exterior of in- a furnace wall. ' The furnace wall as it is shown in the draw 45" ings consists of a row of fluid conducting tubes HI and interposed wall elements or blocks l2 which are of heat resisting material.‘ In the present case they are of metal. The blocks are preferably carried by, the tubes and’ are arranged 50‘ thereon to form a‘ substantially closed furnace wall’;I When a suitable insulation material or refractory material covers the blocks a complete furnace wall will be formed. The interior or 7 fireside of this wall is illustrated in Fig. 2 of 55:‘ the "drawings; The wall may be made airtight two complementary blocks into wall closing posi tions with the blocks resiliently held against the tubes/so that expansion does not decrease the quality of the heat transfer contact between the tubes and. the blocks. ‘ The illustrated. blocks thus 35 permit the assembly or repair of the furnace wall from points without the furnace. A work man need not go into the furnace to- place the wall blocks in position. This is an important advantage especially in the repair of furnace walls before the furnaces are completely cooled, or when the structure. is. located in a. position as for example adjacent boiler tubes so as to make it inaccessible from the inside of the furnace. 45 As clearly indicated in Figures 3,_ 7, and 8 of the drawings each wall-v block has an. inner por tion or face 24 joined with an outer portion 20 by a narrow intermediate'section' bounded by curved faces 26 ?tting tightly against the tubes 50 in the completed wall? structure. The face 24 rests against the furnace sides of‘ the tubes and is presented toward burning fuel in the furnace. 'I‘hisintermedia-te section may be-termed a bout. It is reinforced by an external ?ange or rib 28 55 2,047,907 extending to a base which forms the stud 30 around the opening l8. When the wall elements are in their operative positions, the outer portions 20 'form strong re inforcing ribs or ?anges as clearly indicated in such ?gures as Fig. 4. These ribs extend trans versely of the tubes as shown and operate to’ ma terially stiffen the entirewall structure and main tain thetubes .“in. their ,c'spaced relationships, The 2. In a furnace wall, spaced wall cooling tubes, wall blocks or closure. members insertible be tween the tubes from the exterior of the furnace and contacting with the tubes along spiral lines when in their operative positions; and tension members exerting their forces in directions par; allel to the longitudinal axes of the tubes to hold the blocks against, the tubes so as to have a heat’ transfer relationtherewith. I, _ . . 10 inner portions'or'faces 2'4 formstren'gthening ribs ‘ 3. In a furnace, a row'of 'spaced'fluid con which extend across the inner sides of the tubes fducting tubes delineating a furnace Wall, coact- V as indicated in Figs. 1 and 2. The faces 2d 'of‘ ‘ing wall blocks of identical construction having some of the adjacent blocks orfwallelements may -. partsextending across the inner and outer sides contact with each other as'lindicated in Fig. 1., 15 of the tubes and forming ‘with the tubes a sub-v When the wall elements are inthe'ir' operative ' ,stantially‘continuous and complete furnace wall, positions as indicated in Figr‘l ‘of 'théjdrawing‘sf and means engaging the parts of the wall blocks adjacent elements extend convergently outwardly ' ‘extending across the sides of the tubes remote ' of the Wall so as to form pocketslinv whiéhTe :from the. interior of the furnace to exert pres fractory material may be held. Such material,‘ whether in the form of slag deposited from'burne ing fuel, or in'the form,‘ of- a refractory layer which; is manually placed .over. the, wall, may cover the. portions lof..itheqtub,es, which are not covered by the wall elements themselves-.1 Pref.-. 25 erably, the‘ blocks or wall, elements‘ are,‘ formed with studs 32 shown as extending iIITdlI‘GCtiOIVIS normal ,to :the outwardlyconverging faces of the 3.0; sure on those parts to bring intermediate por tions' of the blocks into closely ?tting contact 20' ,with the surfaces, of the tubes extending, from their furnace ‘sides to'their remote sides. ‘ , 1 4.1m‘ ?uid heat‘ exchange apparatus, a row'of ?uidconducting tubes delineating a furnace wall, , andywall blocks of identical construction each blocks. These. studs, however; are not employed engaging both the forward and rearward sides of the tubes with their parts engagingwthe rear ward sides'of the tubes constituting also a part When'the blocks‘are not covered. ofthe furnace wall presented toward the interior ; . ' , . As shown the blocksare; formed :on their inner sides with ribs 34 which .preferably contact with eachnotherwhen the blocks. are ‘being brought into their [operative relations, with the tubes.‘ of the furnace. ' .; ' 1, - . ' 5. In a furnace wall, spaced substantially par allel support members, and a bloclcunit for clos ing the space between said support members, said block unit comprising two parts of. identical con 3.5. the two blocks. there shown are'moved _.slight1y , struction each having two substantially _longi_-‘ 35; towards each other, the ribs34 will contact and tudinal concave surfaces for engagin'g‘the two ad~ , Referring again to Fig. 9~ofgthe drawings, after formin effect a fulcrumabout which the, blocks are turned as they are;beingstightened-against the_tubes-by tensionapplied by the members It V 40; and the nuts 22 thereon. , The ribs 34 also operate to, form, with the tubes, and the studs 32 :addi-~ tional pockets in which refractory ,material may be positioned. . ;.1, .7, . ' The illustrative wallblocks are. of such form that- they may readily form jalcomplete. furnace wall, even where the wall is supported byv curved tubes as indicated in Figs. 5and .6.-of the draw ings, , They, are,» as adaptable for forming a part of: thejfurnace wall ,which ‘is. convextowards 50, the interior of, the furnace ,aswell as they are upon the wall which is concave towards the in: teriorof. thefurnace- l2 . ‘ ' ' > ‘ jacent support members forwardly. and -rear'-_ wardly of their center line, and means for mount I ing said unit toproduce pressure ‘between the sur» ‘ faces on the parts and the’ support, membersrv ’ 7 ‘i0. 6. In a furnace wall,v spaced substantially par allel cylindrical support members, and a block > unit for closing the space between'said support. members, said block unit comprising’ two parts of identical construction eachhaving two "sub, stantiallyjongitudinal concave surfaces for en gaging the two adjacent suppOrt members?or wardly and rearwardly ofthe commoncenter line of the; members, and means. for mounting said unit to produce pressure between the sur: faces on the parts and the support, members; ‘ , 17. Ina furnace wall, spaced substantially par Besides presenting the, advantage of permitting V allel water tubes, and'a block unit for closing the the wallblocksto beplaced from positionsexf space between said tubes, said block unit com 55, teriorly of the. .furnace,_ the illustrative rembodiel prising two parts of identical construction each merit, Of the invention presents an additional im ' portant advantage .thatall. Qfihe Wa11..b1_0ck elements may be’ ofthe same formation, This promotes'considerable economies in the-assembly 60. andrepair of furnaces, reducing the varietyof parts which must" be kept on‘ hand 'for'ffurna'ce repair. - While the _, invention , ,has’be'en', .. described , _ . with reference to the particular‘ embodiment shown in 65 the drawings, it is to 'be understood that the in having two. substantially longitudinal concave surfaces, for-engaging the two adjacent tubes forwardly ‘and rearwardly of theircenterjline, and means for mounting?saidgunit totgproduce pressure between the surfaces ‘on theparts and the tube,’v _ a ' > >_ v 1: - . V_ 8.~ A furnace ‘wall comprising spaced vertical water tubes, block units insertable between. said tubes sfromroutside the furnace for. closing'?the spacesbetween the tubes, each block unit :com-v vention is not limited: thereto-but is of ‘a scope commensurate withfthe. scope of the‘ sub-joined prising two identical parts disposed one above the other when in position between said‘tubes, claims. '4 What 1. In aisfurnacewall, _' claimedis: , ' spaced _j, ,. wall'cooling I -' ' 1' ; 1: '- _tubes, = pressure betweenthe parts and the tubes'. .7 j v f > .39. A furnace wall comprising spaced parallel and means lfor mounting said unit to produce '10 closureimembers mounted _ upon theq-tubes for, closing the spaces between-‘the: tubes, and tension members each exerting aforcein a direction para vertical water tubes; and-a seriesvofblock units closing the spaces'betweenfsaid tubes; each block unitvv comprising two-parts each having two longi4 allel-to the ,IOnsitudinaLaXBS. of; the tubes-for. tudinal concave surfaces for contact with the two" 7,5; holding said members in. .ceataet withing tubes-'7 adjacent tubes'forwardly and rearwardly of their 501' 3 animal)? center line; a rearwardly extending: flange, and nut and bolt means coacting with ther?anges on each part comprising. a block unit for mounting saidunit to produce pressure between thesur faceskonthe parts and the tubes, substantially as. described. '1 _ V V I 10. In a furnace construction a rowof spaced ‘ ?uid conducting tubes, furnace wall elements of similanconstruction contactingwith the tubes 10 and forming therewith a substantially complete wall or furnace gas boundary, and tension means positioned on the exterior side of therow and acting against adjacent parts of two of said ele ments to cause them to be clamped against the bars, enacting with thetensionmembers to main tain 1the "closure, members resiliently pressed against the tubes. . ' ' » . .:; 17. In a furnace wall, spaced wall cooling tubes, metallic wall blocks or closuremembers of .iden tical-construction insertible between the tubes from the exterior .of the furnaceand contacting with the tubes along spiral lines when in their operative positions, tension members exerting their forces along the tubes to hold the blocks 10 against the :tubesso. as to. have agood heat transfer relation, therewith, and resilient mem bers "coacting with the tension members and the closure members to maintain the latter resil iently pressed against the tubes under all condi adjacent tubes, each wall, element having a part ' . which closely ?ts the tubes across their furnace tions of expansion and contraction. , sides-and another part which closely ?ts the tubes i‘ 18.. A double concave furnace wall block with across the other sides remote from the interior of ~ itsrconcave sides each bounded by a surface ex tending along‘a' helical curve and adapted to ?t the furnace. , 1 ‘ , 20 _ ,11. In a furnace, a plurality of spaced ?uid tightly against a tube when the block is arranged conducting tubes outliningya wall, wall blocks of obliquely'with reference to the longitudinal axis 15, similar construction insertible between thetubes from the exterior of the furnace and having parts extending along the inner and outer sides of the 25. tubes tocomplete the furnace walls and substan tially, close the spaces between the tubes, and tension means ‘acting upon portions of adjacent wall‘ elements to cause them to tightly grip the tubes so that they are held in position thereby. 30 ', ,v l2.v In a'furnace wall, spaced wall cooling tubes, closure members mounted upon the tubes for closing the spaces between the tubes, tension members each exerting force in a direction paral-. 35 lel to the longitudinal axes of the tubes for hold ing said members in contact with the tubes, and resilient members coacting with the closure mem bers to maintain them resiliently pressed against the tubes. ', 13. In a furnace wall, spaced wall cooling tubes, 40 wall blocks or closure members insertible between the tubes from the exterior of the furnace and contacting with the tubes along spiral lines when in their operative positions, tension, members exerting their forces in a direction parallel to the 45 longitudinal axes of the tubes to hold the blocks against the tubes so as to have a heat transfer relation therewith, and resilient members coact ing with vthe tension members and. the closure members to maintain the latter resiliently pressed 50 against the tubes under all conditions of‘ expan sion and contraction. , ‘ " 14. In a furnace wall, spaced‘wall cooling tubes, ‘closure members mounted upon the tubes for closing the spaces between the tubes, and tension 55 members each exerting force in a direction paral ' lel to the longitudinal axes of the‘ tubes for hold ing said members in contact with the tubes,ja1l of said closure members being of identical con‘ struction and constituting the only wall forming members in contact with the tubes. ' " "15. In a furnace wall, spaced wall cooling tubes, wall blocks or closure members insertible between the tubes from the exterior of the furnace, tension members exerting their forces in a direction parallel to‘the longitudinal ‘axes of the tubes to hold the blocks against the tubesrso as to have a of the, tube. . ., 19. A double concave furnace wall block. with its curved sides constituting parts of tube ?tting helices adapted to fit tightly against cylindrical 25 tubes when the 'block is arranged obliquely thereto. ‘ ' ' > ' 20.*'A. metallic double concave furnace wall block having its opposite sides bounded by tube ?tting surfaces which arepa'rts of helices when the block is arranged obliquely relative to the tube. . ' ' ‘ - 21. In combination with furnace wall tubes, a double concave metallic furnace wall block com prising, a clamping part, an inner tube engaging 35 part adapted to be disposed transversely of fur— nace wall tubes along their furnace sides, and a double concave intermediate part connecting the above indicated parts and bounded on opposite sides by, surfaces which are. adapted to ?t tightly 40 against'adjacent' tubes. and constitute parts of tube enclosing surfacesin the nature of helices. 22. In a furnace wall, wall tubes, pairs of blocks shaped to ‘?t. the tubes when oblique, to the tubes with the blocks of each pair diverging, and means 45 acting on the blocks to ‘change their obliquity and thereby cause the blocks to be clamped against, the tubes. the blocks completing the fur nace wall closure when clamped in position. 23. In a furnace, spaced tubes, metallic wall 50 units having inner and outer sections positioned on opposite sides of the tubes and connected by sections oblique to the tubes, and means acting on the outer sections to cause the units to be bound against the tubes; the units being insert ible between adjacent tubes from a position ex teriorly of the furnace. > I I 24. In the furnace art, the method of building a,‘ furnace wall comprising arranging spaced tubes ‘in wall'delineating relationship, insert ing wall, elements between the tubes from po sitions exteriorly of the-furnace, turning those elements to interlock them with the tubes, and pivoting the blocks on_a transverse axis, then exerting pressure onthe elements to further pivot 65 them, and thereby bind them into good heat ex heat transfer relation therewith,‘ and resilient devicesinterposed relative to the tensionimem change relationship with the tubes. :25. A_furnace wall ‘structure for closing the bers and the‘closure devices.‘ 1 I 70 I » ‘l6.“In? a furnace wall, spaced wall'cooling tubes, spaces between adjacent tubes comprising, an inner portion constructed and arranged to bridge the space between two wall tubes and to have its rearward side ?t against the front parts of those tubes; an outer‘ clamping part constructed and arranged to' receive pressure to cause the. struc doubleiconcave closure members obliquely'mount ed upon and between adjacent tubes for closing the *spaces- between the tubes, tension members each exerting aforce along the wall for clamping 75 .. said 'members‘lonl the tubes, and‘ resilient, mem ture to pivot and to be clamped against the tube, 4 2,047,907 a narrow'intermediat'e double concave part: con necting the’above‘ describedparts and bounded at its opposite sides by surfaces'which closely ?t all parallel. to an ate portion.. axisoblique vto said intermedi »34."In a‘vmetallic'ifurnace wall block,.a rela against the sides of two.iadjoining».tubes'when ‘ tively narrow 3 intermediate portion’ connecting the structure" is obliqueltheretm: and .a fulcrum twotransverse end portions which extend. out portion intermediate ~the ends. .of .the structure wardly beyond both sides of theintermediate constructed andarranged to contact with another similar structure and to'causethe-I?rst structure to'be pivoted and brought into good heat ex 10' changerelationship with the-tubes upon the ap plication of ‘pressure-to said'outer part. ‘ '26..Furnaceiwallielements of identical: con struction constructed’ and arranged'to close the spaces between wall cooling tubes and consisting of end portions connected by .double ‘concave mid-portions having their opposite sides inwardly and helically curved .to' form parts iof cylindrical surfaces having their 'axes- oblique to the mid portions to ?t .tightly'against‘wall tubes when the elements are positioned obliquely'with ref-, erence to the longitudinal axes of the tubes,‘ the mid-portions being narrower than said-end-‘por tions?. 'm ' “ *1 . I > ‘ .i 27. A furnace'wall block having wall forming end portions connected. by a. narrow double con cave mid-portion de?ned at its opposite sides by concave tube ?tting surfaces adapted to closely ?t againsta tube'when .theblock is arranged obliquely. thereto, .one. end portion. of the block' being insertible. within the furnace between .ad portion," and a fulcrum forming projection. . v35. Inf‘a metal furnace wall’bloclg-a relatively narrow intermediate portion, end portions'ex tending in‘the same plane beyond opposite sides of the intermediate-portion, and a fulcrum form ing-portion extending from the intermediate por tion in a direction at an angle to said plane. 36. In a furnace; vspaced vwall'cooling tubes; and metallic structural units comprising, trans verse ‘end portions connected by relatively nar row "intermediate portions which-are obliquely re— lated to one end» portion in each unit, and ful crum forming projections, opposite sides of the intermediate portions shaving surfaces de?ned by elements parallel toqaxes oblique to said'intere 20' mediate portions; the end portions'and' projec-q 1 ' tions» being so- constructed’ and’ arranged that ' whilev said units canbernoved between’the' tubes to their‘ operative positions'from positions ex teriorly‘ofthefurnace the units cannot be'moved ~ between successive tubes entirely topositibn's within the furnace, , ' ~ = ~ 7 . a, 37. 'A' furnace wall comprising spaced tubes,’ jac'ent tubes anditheother end portio?havin'g and blocks arranged between and along succes tube, the ?ange being oblique. to the mid-pore blocks presenting furnace‘faces ,both'rea'rwardly a-?ange against which a clamping force reacts . sive tubes innzigzag formation to close the'spaces to. pivot the block‘ and bind‘. it-tightly against a between the tubes and” complete the wall, the tion. . .. . . 28.'In a ?uid. cooled furnace 'wall, a row of spaced tubes, blocks insertible'between the tubes from positions exteriorly of the furnace, and means extending .and acting longitudinally of the 40 tubes and positioned exteriorly. of the row of tubes and forwardly of the center lines of the tubes. ‘ 738. In ‘a furnace wall, a rowpf spaced tubes,- 9 metallic wall blocks’ of similar construction ar ranged in pairs of oppositely'angled blocks be tween successive tubes, the blocks of a pair hav-' ing extensions converging toward a positiongex ‘for pivoting the blocks toibind them against‘the . teriorlyfof the row of tubes, the blocksalso'hav 40 tubes, the blocks being arranged in pairs with ing'inner. extensions ‘or, portions positioned over the blocks of each pairlfulcruming on each other _ the sides of the tubes toward the interior of the as said means is operated'and each block‘ being furnace, and means reacting: against'the blocks to 45 replaceable without the‘ displacement .of any pivot them‘ and cause bothsets of extensions to 45 block' other than the‘ complementary block of .its pairs - 7' ' - 29. A furnace wall block formed with two separate helical and cylindrical tube engaging 50 surfaces each with an axis‘oblique'to the direc non, in: which the block has its maximumTdimen-i S1011; ' " 7' " 7-’ ~ 30.‘ A metallicifurnace Iw‘all- block having a tube 55 ?tting portion and an ‘inner end part forming furnace faces in: front of "the tube ?tting‘ portion, said portion also forming a-"furnace face facing in the same direction as the other furnace-faces. I 31. A. furnace wall block having tube- ?tting portions on opposite-(sides of a fulcrum portionv 60 about which theblock is. pivotable on an axis transverse to' the axes of adjoining tubes. ‘ ' . - 32.'In a furnace, "spaced tubes, unitary wall 65 blocks individually bridging'the furnace sides of adjacent tubes and being'operatively positionable . be clamped tightly against the tubes.‘ ‘ 39. A furnace wall comprising spaced tubes, and blocks arranged between andalon'gsuccessive tubesinzigzag formation relativetoi'the plane of’the' wall to closethe spaces between the tubes and complete the wall,‘ adjacent blocks having so .i refractory anchoring projections extending into wall pockets formed between the blocks and the tubes. ‘ ' 40. In combination; spaced furnace wall'tubes,' 55 wall elementsarranged in zigzag formation rela- . tiver'to the. plane of the wall to. close the spaces between the tubes, the elements having trans verseLend portions positionedon opposite sides of the tubes, and projections transversely re lated to the end portions and cooperating there-. with for preventing the elements fromrpassing entirely throughv the spaces between the tubes 7 while permitting thoseelementsto be ‘placed in position from points beyond the tubes 65 from positions extejriorlyo'f ‘the'furna'ce, fulq operative c'rum parts on' the blocks; an'dvmeans, acting on exteriorly of the’ furnace. the blocks to‘v pivot themion said’ fulcrum parts V _, 41. In a furnace of the typeincludingspaced wall tubes connected into fluid circulation, blocks '_ and about; axes '_ transverseto thelongitudinal closing the spaces between the tubesand'having axes‘ of the'tube's to cause the blocks to, be tightly - body portions jwithidouble concave tube contact clamped against the :tubes. ] ' l" v V . V . ing. surfacesv each generatedby ,astraight line 33. In a metallic'structuralunit, transverse end, element remaininguconstantly parallel to the‘ portions connected, bya relativelynarrow inte'r—j longitudinalaxis of ‘a rightcylinder while it mediate portion, and‘ a fulcrum forming projecé. ' moves, in a helical pathsI , - j - . ' j r '75. tion,j'opposite_ sides of the; intermediate portion: . ; 42. A blockkforspanninkg the space, between two having ‘surfaces de?ned‘by ‘straight line nememz‘s . parallel tub‘és‘wmen comprises abody portionthe V V 5 2,047,907 sides of which are of substantial width and shaped to lie along the tubes and in contact therewith throughout their width and at an angle between 90° and 180° with respect to the axis of the tubes. 43. Double concave furnace wall blocks having opposite tube ?tting surfaces each generated by a straight line element constantly parallel to the longitudinal axis of a tube and moving in a path in the nature of a helix. 10 44. Furnace wall elements of identical con struction adapted to close the spaces between wall cooling tubes and consisting of end portions con nected by double concave mid-portions having op posite surfaces corresponding to exterior tube 15 surfaces positioned between two substantially parallel planes obliquely cutting two spaced and parallel tubes. 45. In combination with furnace wall tubes, a metallic furnace wall block having a tube ?tting 20 portion presenting furnace faces forwardly and rearwardly of the center lines of vthe tubes. 46. In a metallic structural unit having trans verse end portions connected by a relatively nar row intermediate portion, opposite sides of the 25 intermediate portion having curved surfaces in the nature of parts of helices de?ned by straight line elements .all parallel to an axis oblique to said intermediate portion. 47. In a furnace; spaced wall cooling tubes; and metallic structural units comprising, transverse end portions, and relatively narrow intermedi ate portions connecting the end portions, oppo site sides of the intermediate portions having surfaces de?ned by elements parallel to axes ob CH lique to said intermediate portions; the end por tions and projections being so constructed and arranged that while said units can be moved between the tubes to their operative positions from positions exteriorly of the furnace the units cannot be moved between successive tubes en tirely to positions within the furnace. 48. In a furnace wall, spaced tubes, and wall closure elements secured to the tubes and ex tending from positions on the furnace sides of the tubes to positions on the opposite sides of the tubes, said elements presenting furnace faces forwardly and rearwardly of the center lines of the tubes. 49. A method of building a wall comprising, arranging spaced supports in wall relationship, inserting wall closing elements between adja cent supports from positions exterior of the wall, turning those elements to inter-lock them with the supports, pivoting the elements, and then 2 exerting pressure on the elements to bind them into closely ?tting relationship with the sup~ ports. KENNETH NAPIER.