US1510857A - Recuperator coke-oven structure - Google Patents

Description

J. K, MUNSTER aacursm'roa com: ovan STRUCTURE Original Filed Oc t. 24. 1919 5 Sheets-Sheet 1 Oct. 7, 1924 J. K. MUNSTER mscursamon com) ovsn STRUCTURE Original Filed Oct. 24. 1919' 5 Sheets-Sheet 2 Oct. 7, 1924.. 15101857 J. K. MUNSTER RBCUPERATOR COKE OVEN STRUCTURE Original Filed Oct. 24. 1919 s Sheets-Sheet 3 Oct. 7 v 1924- J. K. MUNSTER RECUPERATOR COKE OVEN STRUCTURE Original Filed Oct. 24. 1919 5 Sheets-Sheet 4 7 7 WWWKV 4 m MW w W Oct. 7 i

J. K. MUNSTER RECUPERATOR COKE OVEN STRUCTURE Original Filed Oct. 24 1919 5 Sheets-Sheet 5 Wfii 3.9

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JULIUS K. MUNSTER, OF CARNEGIE, PENNSYLVANIA, ASSIGNQB TO THE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYL- VANIA,

RECUPERATOR GOKE-OVIElN STRUCTURE.

Application filed October 24, 1919, Serial No. 832,877. Renewed February 11, 1922. Serial No. 535,949.

To all whom it may concern.

Be it known that I, JULIUS K. MUNsTER, a citizen of l-lungary, who has declared his intention of becoming a citizen of the United States, residing in Carnegie, in the county of Allegheny and State of Pennsyl vania, have invented a new and useful Improvement in Recuperator Coke-Oven Structures, of which the following is a specification.

This invention comprehends improvements of especial utility in the coking retort oven art; and also comprehe'nds certain improvements applicable generally to structures, the parts of which are exposed to severe destructive forces of expansion or contraction resulting from temperature conditions or changes radically different from normal or ordinary atmospheric temperature conditions.

The invention has for one of its objectsto incorporate in a coke-oven a highly efficient recuperator system for conserving the heat. of the waste gases from the heating Walls of the oven; the novel recuperator system is of great utility in coke-ovens of well-known type embodying parallel heating walls preferably constituted of a plurality of vertical flame-fines, and coking chambers intermediate the heating walls. And the invention includes among its objects the development of a practicable recuperator system for coke-ovens or gas-ovens of whatever magnitude that both permits 9X" pension from heating and contraction from cooling off of the structure without destruction of the recuperator, with elimination of difiiculties and deficiencies common to recuperator systems and generally limiting their utility, especially in large units, and with increased efficiency of operation and ma intcnance.

A further object of the invention is the provision of a highly efficient heat exchanger which although adapted for utilization in the before-mentioned recuperator system, is also of general utility in the art of transferring heat from one medium to another. Structures of this character are subject to heterogeneous ex pansion or contraction produced by the great extremes of temperature and the fact that temperatureconditions vary considerably in different isothermal planes. In a heat exchanger constructed in accordance especially tory structures, for example coke-oven parts,

that are subject tosuch heterogeneous ex pansion or contraction, said joint being of a composition having an inherent nature for accommodating such expansion or contraction of the parts which will prevent inter change of gases and thus preserve substantial gas-tight conditions under all circumstances, and additionally having an inherent insusceptibility to change in its physical characteristics when exposed to such temperature changes.

In the accompanying drawings, forming a part of this specification, and showing, for purposes of exemplification, a preferred form and manner in which the invention may be embodied and practiced, but without limiting the claimed invention specifically to such illustrative instance or instances Figure 1 is a composite vertical. sectional elevation through a coking retort oven of a type embodying features above specified and equipped with the improvements of the present invention.

Figure 2 is acomposite transverse section and elevational view showing both the coke and pusher sides of the coke oven illustrated in Figure 1.

Figure 3 is an enlarged detailed fragmentary vertical section taken in a plane indicated by'the line of Figure 2. a

Figure 4 is an enlarged detailed fragmentary vertical section taken ina plane indicated by the line 4-4 of Figure 1.

Figure 5 is an enlarged detailed fragmentary horizontal section taken in a plane indicated by the line 5+5 of'Figure 2.

Figure 6 is an enlarged detailed frag; mentary horizontal section taken in a plane indicated by the line 66 of Figure 4. 1

Figure 7 is an enlarged detailed fragmenta y horizontal section'i-aken in a plane Y indicated by the line 77 of Figure 4.

Figure 8 is an enlarged detailed fragrnentary horizontal section taken in a plane indicated by the line 88 of Figure 4.

Figure 9 is an enlarged detailed traginentary horizontal section taken in a plane indicated by the line 9- 9 of Figure 1,

Figure 10 is an enlarged detailed frag ment-ary horizontal section taken in a plane indicated. by the line 10* 10 of Figure 1.

The same characters of reference in the several figures indicate the same parts.

In its present embodiment the invention is incorporated in a coking retort oven or coke-oven battery provided with crosswise extending parallel heating walls constituted of series of vertical flame-Hues and elongated coking chambers intermediate the heating walls and parallel therewith. For convenience, the present description will be confined to this use of the invention; features of construction are, however readily susceptible of other valuable applications and, consequently, it is manifest that the scope of the invention is by no means confined to the specific use and specific embodiment herein described as an illustrative example.

Referring to the drawings there are illustrated sectional views of a coke-oven battery of the by-product type, such as has been hereinbefore mentioned, which embodies in its construction a plurality of crosswise elongated vertical heating walls 1111 and a plurality of intermediate crosswise elongated vertical coking chambers or ovens 1212. The heating walls 11 formthe side walls of the respective coking chambers 12 and are supported by the heavy supporting or pillar walls 13-l3 extending crosswise of the battery, and in the present instance, beneath the respective ovens or coking chambers 12, as particularly illustrated in Figures 1 and 2. These pillar walls collectively form the main support for the entire superstructure of the oven battery, and are themselves firmly-supported upon a flat mat or platform, which constitutes the subtoundation on which the entire battery rests. The opposite sides of the battery are designated the pusher and coke sides respectively and the ends of the coking chambers or ovens 12 at each side of the battery are fitted with removable doors 15 of a construction well known in the art, whereby the charges of finished coke may be discharged from the ovens in the usual way.

The side walls of the battery on both the pusher side A and the coke side B are braced by pairs of vertical buck stays 16. the respective members of each pair of buck stays being located on opposite sides of the coke oven doors. As shown more particularly in Figure 2, the members of each pair of buck stays are formed with converging portions 17 located between the bottom of the several ovens or coking chambers 12 in order that the lower portions 18 of the respective pairs of buck stays may extend directly in front of the pillar wall 13. These lower portions 18 of the buck stays are braced by horizontal ties 19 con necting the members of each pair; the upper portion of the buck stays are also braced by ties 2O connecting adjacent members of adjacent pairs of buck stays. The side walls A B of the battery may be further braced if desired by suitably positioned horizontal beams 21 connecting the several buck stays on each side of the oven battery.

The coal to be coked is charged into the several coking chambers or ovens 12 through charging holes 22 located in the top 23 of the oven battery and positioned. directly above the ovens or chambers 12, shown in Figure 1. These charging holes 22 are equipped with removable covers 24 which are removed when charging any of the sev eral ovens and placed in position during the entire coking operation.

Heat for coking the charges of coal in the several ovens or chambers 12 is derived from the heating walls 11, which as before mentioned extend crosswise of the battery at the sides of the coking chambers and are, in the precent instance, each provided with a set of vertical heating or flame tlues 25 constituting elongated chambers for the combustion of gaseous fuel in an atmosphere of highly preheated air. Gaseous fuel for each set of heating flues 25 is supplied through gas conduits or channels 26. there being a gas channel for each set of heating fines. The several channels 26 extend lengthwise through the pillar walls 13 and communicate with discharging ducts 27 individually extending to individual heating fines as shown. Each of these gas-ducts may be fitted with a suitable nozzle 28 for insuring the admission of regulable quantities of gas into the rcspectivc heating fines. Above each heating line 25 is an access flue or chamber 29 ex tending to the top oi the oven battery and normally closed at its upper end by means of cover 30. By the removal of the cover 30 or any one of the access flu-es 29. and pushing aside the usual slide brick which is located at the bottom of each access fine, the interior of the heating flue below may be conveniently reached, for example it it be desired to change a nozzle 28.

In accordance with the present invention, the air necessary For the combustion of the gaseous tuelin the several sets of heating fines is preheated by effecting a heat exchange between the waste gases From the "flame passages of the heating walls and the fresh air before the latter enters said passages to support combustion of the gas therein; and this preheating ot the air is accomplished by means of a highly efficient, though simply constructed and economical rccuperator system. The chambers located between the several pillar walls13 constitute recuperator chambers or bays, the latter term being employed by reason of the recess nature of said chambers and conveniently utilized in ageneric sense in the ensuing description. These recuperator bays, in the present embodiment, extend respectively crosswise of the oven battery below the heating walls 11, with their sets of flame flues 25, and parallel therewith. Each recuperator bay 31 constitutes a chamber or common passage for the circulation. of one medium while the latter is engaged in the heat exchanging operation, and according to the illustrated embodiment of the invention the waste heat gas from a set of flame flues 25 flows from said set of fines to and through the common passage of the recuperator, below and corresponding to that set of heating flues. For this purpose, each recuperator bay communicates with all of the flame flues of the heating wall corresponding thereto and such communication isconveniently afforded by means of vertical outflow channels 32 located in each heating wall 11 and preferably in alternation with the several flame flues therein. These vertical outflow passages 32 individually communicate with individual flame flues near the upper ends of the latter through ports33,as shown, and said outflow channels extend downwardly to the tops of the recuperator bays, with all of the channels leading from a wall of flame flues discharging into a single recuperator bay,- as will be readily, understood from an inspection of the drawings.

Within each recuperator bay 31, is a series of conduits, in the present instance for the circulation of fresh air that is directed by said conduits into theflame flues 12 of the heating"wall corresponding with the recuperator bay, the fresh air being preheated during its passage through the aforesaid conduits and utilized in the flame flues for supporting combustion of the gaseous fuel supplied thereto by the nozzles 28'. According to the present embodiment of the invention, the individual conduits of each recupera-tor bay respectively communicate with the individual flame flues of the co=r-. responding heating walls; each conduit consists essentially of a columnar recuperator stack 34 structurally independent of the other recuperator stacks within the recuperator bay. Each stack 34 is consequently ex p ansible and contractible, under temperature changes in the recuperator bay, inde-' pendently of the others and independently of the coke-oven structure above the recuperato-rbay. Each stack 34 may be formed of a plurality of short tubular sections 35 having open ends so that a continuous con-. duit or passage is formed when a number of such connections are assembled into a stack. The lowermost member or tubular section 35 of each recuperator stack is firmly supported on the base 14 inany suitable manner,

as shown in Fig. 2, and the remaining members 35 are positioned one above the other upon said lowermost member or section, being supported freely upon each other, preferably by gravity alone. As a result of this construction, the weight of the several members of a recuperator stack upon each other will keep the horizontal joints tight. The several members constituting a recuperator stack may thus expand or contract independently of each other and may also move. sidewisefi Vertical joints, which would of necessity have to be sealed, are entirely eliminated in the recuperator stacks, and the horizontal joints which are closed by the weight of the several tubular sections 35 upon each other.

lie in planes parallel with the isothermal planes in the recuperator bay, sothat heterogeneous expansive or contractive forces,

due to different temperature conditions in the different strata of the recuperators will not causethe joints to open. A recuperator system made up of units constructed in the foregoing way is not only an exceedingly simple and eflicient design, but is also practically insured against short circuiting of the air currents, and is inherently capable of heterogeneous expansion or contraction horizontally, v without the production of stresses acting as opening, slipping or cracking forces.

If desired, each tubular section 35, may be formed at one end with an outwardlyprojecting annular flange 36 and its oppo site end with an inwardly-projecting flange 37. In assembling the tubular sections 35 into stacks the inwardly projecting flanges 37 of adjacent sections are disposed a'dja-' cent to each other and-concurrently the outwardly-projecting flanges 36 of adjacent sectlons are similarly disposed, as shown in F ig, 2. I Y

The topmost section 35 of each recuperatorstack is provided with a seat 36 mounted thereon in a suitable manner and preferably formed with a vertical projecting peripheral flange 37 as shown more par ticularly in Figures 3 and 4. Mounted on the seats of the several recuperator stacks 34, within each recuperator bay, are nozzles 38, the latter beingsupported on their seats by gravity alone, and thus; capable of horizontal shifting motion on their seats, when the structure is subject to widely different temperatures causing expansion or contraction to diverse extent at different levels. These nozzles 38 constitute, essen tially, parts of their corresponding recuperator stacks, and, preferably, theyproject vertically within the communicating flame-fines 25 of the recuperator stacks. In order to prevent leakage from the flamelines 25, past the nozzles 38* there is provided in accordance with the present invention, a novel joint construction, which though substantially tight against the gaseous matter in the flametlues, is nevertheless fluent in its nature to accommodate diverse expansion or contraction of" the recuper-ator hay and heating wall. structure. These joints are formed of material that will flow into and seal any chinks or cracks between the adjacent nozzles and any portions of the heating walls and which is substantially non-agglomeratic when subjected to the exceedingly high temperatures produced at such portions of the wallsv One material e'llicient for the formation of these joints is ordinary silica sand, in that it runs freely to fill up any chinks, cracks or open spaces caused by expansion or contraction of the adjacent parts, is substantially gas-tight under the pressure existing in. the flameflues, and does not agglomerate or form itself into lumps under the temperatures produced. The method of to-ri'ning the joints is exceedingly simple. The closures 30 at the tops of the access-tines or chambers 29 may be opened and a quantity of sand may be introduced through the access-fines and flame-Hues, into the space between each nozzle 38 and the surrounding portions of the heating walls 1].. The sand flows through these spaces and the bottom part-s of the sand rest upon the seats 36", thus forming joints 39 which accom modate themselves to heterogeneous expansion or contraction of the stacks and the'sur-- rounding portions of the heating walls, and reserve substantially gas-tight conditions. in practice it will generally be found better to introduce the sand after the oven battery has been .heated to some extent. The toundation mat and entire series of stacks in each recuperator bay may thus expand or contract heterogeneously with. respect to the structure above them without giving rise to opening or cracking forces, and the joints serve at all times absolutely to prevent interchange between the gases in the flameflues of the heating walls, and the gases in the recuperator bays beneath. Difi'erences of expansion or contraction in the different isothermal planes are thus permitted, throughout, without the formation of cracks and crevices in the recuperator stacks and short circuiting of the various heat currents and interchange of gases is practically eliminated. As the walls of the recuperator stacks are not subjected to cracking forces and stresses, they may be made much thinner than could otherwise be done, thereby reducing the conductive resistance to interchange of heat in the recuperator bays.

The air for supporting combustion in the flame-Hues 25 is derived from the outside atmosphere and enters the coke oven battery through inflow conduits, or sole channels 410 formed in the base 14, as shown in Fig ure 2. These sole channels are respectively located beneath sets or series of recuperaltor stacks 34: in the several recuperator bays and are respectively provided with ports il, individually communicating with individual recuperator stacks. The air flows upwardly through the recuperator stacks 34, and in so flowing is highly pre heated by the outflow discharged into the recuperator bays 31 by the outflow passage 32, and finally the air discharges into the flame-fines 25 greatly preheated and thus capable of greatly augmenting the flame temperatures within the said flues. As stated the waste products from the flame flues discharge into the recuperator bays 31, and these waste gases are subsequently carried oil? through ports 42 formed in the pillar walls 13 and leading to exhaust conduits 43, there being an exhaust conduit tor each recu tierator bay. The several exhaust conduits 43 extend to discharge pipes 44 which carry the waste gases into the stack conduit, indicated diagrammatically at 45. If desired, the outflow may be regulated by a sliding brick 46 adapted to vary the size of the opening between each conduit 43 and its corresponding discharge pipe 44. The sliding bricks 46 may be manipulated through small openings 47 in the coke oven wall.

The gas conduits 26 which extend crosswise through the coke oven and respectively supply the. flame-fines of the respective heating walls 11, may receive their supply of gas from gas mains located on either side of the coke oven battery. This construction permits the use of either producer gas or coke oven gas in the same oven, or any two gases of different character without sub stantial change in the oven construction. For example, a producer-gas main 48 may be located. on the coke side 13 of the oven, and a coke-oven gas main 49 may be located on the pusher side of the oven. The hotproducengas main 48 is connected by means of valve-controlled pipe connections 50 with the several gas conduits 26, and the cokeoven gas main 49 is also connected with the opposite ends of the several gas conduits 26 by means Of valve-controlled pipe connections 51. Vith this construction either producer-gas or coke-oven gas may be used in the flame-fines 25 by manipulation of the pipe connections 50-51. If desired, producer gas may be used in part of the heating walls 11 of the battery and coke-oven gas in the remainder; or all of the heating walls may be heated by the same kind of gas. This choice is made possible by the fact that the pipe connect-ions 50-51 are all entirely independent of each other.

The recuperator stacks within the several recuperator bays are substantially leakproof against the wasteheatgases, in that they accommodate themselves to widely heterogeneous expansion or contraction of the battery without the formationot chinks or cracks; and they are not liable to clogging with dust carried in the air or gas flow, inasmuch asthey are vertically arranged, and any dust precipitated in them will drop into the sole channel conduits beneath them where such dust may readily be removed.

' The invention as, hereinabove set forth is embodied in a particular form of construction, but may be variously embodied within the scope of the claims hereinafter made.

Whatis claimed is:

1. In a coking retort oven, in combination: coking chambers; sets of heatin flues parallel with the coking chambers an contiguous thereto; recuperator bays, each located below a set of heating fiues and parallel therewith; outflow vertical channels individually connecting the heating lines of each set with its corresponding recuperator bay; recuperator stacks located within each recuperator bay, said stacks being structurally independent of and freely movable with respect to each other and communicating with the heating flues above the stack; exhaust conduits communicating with the recuperator bays; and supply conduits communicating with the recuperatorstacks in each recuperator bay; substantially as specified. v I

'2. In a cok ng retort oven, in comblnation: coking chambers; heating lines; and

recuperator bays respectively provided with individual conduit units structurally independent of the bays and a common passage surrounding said conduits, the individual conduits of each recuperator bay communicating with individual heating fines, and the common passage of each recuperator bay communicating with a plurality of heating flues; substantially as specified.

-3. In a coking retort oven, in combination: coking chambers; heating fines; and recuperator bays respectively communicating with a plurality of heating flues and each recuperator bay provided with columnar conduit units supported solely at their bottoms and freely movable at their tops, said conduit units individually communicating with individual heating fiues; substantially as specified.

4. In a coking retort oven, in combination: coking chambers; heating flues; and recuperator bays respectively communicating with a plurality of heating fines and each recuperator bay provided with c0- lumnar conduit units formed of superposed members movable horizontally with respect to each other to permit free expansion and contraction of the individual columnarc10 n duit units in planes respectively of difierent temperatures, said conduit units individually communicating with individual heating fiues; substantially as specified.

5. In a coking retort oven, in combination: coking chambers; heating fiues; and recuperator bays respectively 'communicatt ing with a plurality of heating lines and each recuperator bay provided with columnar conduit unitsformed' of individually movable members supported freely one upon the other, said conduit units individually communicating" with individual heating flues; substantlally as specified.

6. In a coking retort oven, in combination: coking chambers; heating fines; and recuperator bays respectively communicating with a plurality of heating fluesand each recuperator bay provided with columnar conduit units formed of individually movable members supported one upon the other by gravity alone, said conduit-units individually communicating with individual heating fiues; substantially as specified.

7; In a coking retort oven, in combination: coking chambers; heating fiues; 'recuperator bays respectively communicating with a plurality of heating fines and each recuperator bay provided with individually expansible and contractible conduit units, said conduit units individually communicating with individual heating flues; and selfsealing movable joints respectively connectrecuperator bay provided withfindividually" expansible and contractible conduitv units, said conduit units lndlvldually communicating with individual heating flues; and" joints, formed of constantly fluent solid material, respectively connecting said conduit units with the walls of their communip atingheating flues; substantially as speciied. i

9. In a coking retort oven, in combination: coking chambers; heating flues; recuperator bays respectively communicating with a plurality of. heating flues f and each recuperator bay provided with individually eXp-ansible and contractible conduit units, said conduit units individually communicating with individual heating Hues; andjoints, formed of freely-flowing material, respectivelyconnecting said conduit units with the walls of their communicating heating flues; substantially as specified. I

10. In a coking retort'oven, in combination: coking chambers; heating fiues; recuperator bays respectively communicating with a plurality of heating fines and each recuperator bay provided with individually expansible and contractible conduit units, said conduit units individually communicating with individual heating fiues; and joints, formed of fluent solid material nonagglomeratic by coking heat, respectively connecting said conduit units with the walls of their communicatingheating fines; sub stantially as specified.

11. In a coking retort oven, in combination: coking chambers; heating flues; recuperato-r bays respectively communicating with a plurality of heating fines and each recuperator bay provided with columnar conduit units, formed of individually expansible and contractible members, said conduit units individually communicating with individual heating fines; and joints, formed of fiuent solid material non-agglomeratic by coking heat, respectively connecting said conduit units with the walls of their communicating heating fines; substantially as specified.

12. In a coking retort oven, in combina tion: coking chambers; heating fines; recuperator bays respectively communicating with a plurality of heating flues and each recuperator bay provided with individually expansible and contractible conduit units, said conduit units individually communicating with individual heating flues; and joints, formed of fluent silica sand, respectively connecting said conduit units with the walls of their communicating heating flues; substantially as specified.

13. In a coking retort oven, in combination: coking chambers; heating fiues; recuperator bays respectively communicating with a plurality of heating fines and each recuperator bay provided with conduit units, said conduit units individually connnunicating with individual heating flues; and joints, formed of fluent solid material non-agglomeratic by coking heat, respectively connecting said conduit units with the walls of their communicating heating fines; substantially as specified.

14. In a coking retort oven, in combination: coking chambers; heating fines; recuperator bays respectively communicating with a plurality of heating fines and each recuperator bay provided with conduit units, said conduit units individually cOmmunicat ing with individual heating fines; and joints, formed of sand non-agglomeratic by coking heat, respectively connecting said conduit units with the walls of their communicating heating fines; substantially as specified.

15. A. heat exchanger comprising, in combination: a chamber for the circulation of one medium; and a plurality of conduit units within said chamber for the circulation of the other medium, each conduit unit being formed of individually movable memnames? bers directly supported freely one upon the other; substantially as specified.

16. A heat exchanger comprising, in combination: a chamber for the circulation of one medium; and a plurality of conduit units within said chamber for the circulation of the other medium, each conduit unit being formed of individually movable members directly supported one upon the other by gravity alone; substantially as specified.

17. In a coking retort oven, in combina tion: coking chambers; heating walls con tiguons thereto; and recuperator bays communicating with the flame passages of said heating walls, each recuperator bay provided with columnar conduit units laterally expansible and contractible independently of each other, said conduit units also communicating with said heating passages; substantially as specified.

18. In a coking retort oven, in combination: coking chambers; heating walls contiguous thereto; and recuperator bays communicating with the flame passages of said heating Walls, each recuperator bay provided with columnar conduit units laterally expansible and contractible independently of each other; substantially as specified.

19. In a coking retort oven, in combination: coking chambers; parallel heating walls intermediate the coking chambers; gas conduits extending from side to side clear through the oven and respectively communicating with the heating walls; a gas main located on one side of the oven and adapted to supply all of said conduits; a gas main located on the other side of the oven and adapted to furnish an alternative supply of a different gas to all of said conduits; and valve-controlled connections interposed between said gas mains and the gas conduits; substantially as specified.

20. In a coking retort oven, in combination: coking chambers; sets of heating fines contiguous thereto; gas conduits respectively communicating with the individual heating fines of each set; a producer-gas main located on one side of the oven; a

coke-oven gas main located on the other side of the oven; and valve-controlled connec tions interposed between said gas mains and the conduits; substantially as specified.

21. In a coking retort oven, in combination: coking chambers; heating walls contiguous thereto and intermediate said coking chambers; pillar walls located beneath the coking chambers; vertical buck-stays secured to the sides of the oven and formed with their upper portions positioned directly in front of the heating walls and with their lower oilsct portions: positioned directly in front of the pillar walls; and

,crosstie means extending over the faces of the heating walls and the pillar walls and connecting the mutually adjacent upper and lower portions of the buck-stays, and tying such buck-stays together into a unitary frame; substantially as specified.

22. A furnace construction having a set of vertical heating fiues, combined with a set of vertical recuperator tubes respectively leading to said heating flues, the entire set of recuperator tubes having expansible and contractible joint-connections with theheating fiues and each recuperator tube being free to expand or contract independently of the other recuperator tubes, to permit eX- pansion and contraction of the furnace structure Without injury to the recuperator tubes, substantially as specified.

23. In a recuperative coke oven battery the provision of air conduits situated in the path of the gases of combustion, said conduits being formed of horizontally-movable independent sections seated one upon an other.

24. In a coke oven battery, air conduits situated in the path of the gases of combustion, said conduits being formed by independently-movable horizontal hollow sections seated one upon the other.

25. In a coke oven battery, air conduits situated in the path of the gases of combustion, said conduits being formed of associated sections with horizontal joints therebetween.

In testimony whereof I have hereunto set my hand this 21st day of October, 1919.

JULIUS K. MUNSTER.

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