US2396976A - Blast furnace - Google Patents

Description

BLAST FU'RNACE Filed Jan. 18, 1944 Z'Sheets-Sheet l 9&5 MW,

Mach 19, 1.946. G. A. WHITEHURST Shee'S-Sheet 2 BLAST FURNACE Filed Jan. 18, 1944 Patented Mar. 19, 1946 UNITED STAT ES;- PATEN'E VFFICE BLAS'l"FURNGEl l GcorgefAl; Whtehurstt; Mount Lebanon, Pa., as.-`

signor tofCarnegieelllinoisi-Steel' Corporation, 'a

corporation of Ne'vv' Jersey Applicationzlannaryl, 1944;;fScraliNm518,765:

7 Clan'sil. (Cl. 26S-32).

A`s presently constructedgblast furnacesA usueally-A are lined?" throughout*l with'. fire-clay:v brick.

The-quality of this brickl is-adjustedtofmeet the particular requirements of-v different zones of?V the furnaceJ which are` dividedl intofour secti'onsY or parts; namely; the-hearth,V hash, lowen-inwall and upper inwalli The brick of the hearth 'is subjectedltothe=- actionr oihighlternperature: and

slag without-being required to stand? any loads or abrasion; Y On this account; its properties-are selected; to showf a1 maximum resistance-'to temperature andi. chemicalaction. Ifn'A Vthe boshi.

section;- the bricl:- isr subjected to-` avery high-1- temperatur-e; attack by the' slag, and -someabrasive action of eolie-passingrL over it, but again it isnot required. to; stand'- any load; Its char-- acterist-ics are adjustedl for high chemical' inertness andi` temperature# stability without l any particular attention to'- thev mechanical' properties. the requirements almostequal 'toi those` of the bosli'A section# from -sl'aggingfand `ternperatm'eA stan'dpoints; and at the s'arne` time must support theweight of# the entireliningon the inside off' the shaft and stand severe abrasion'oausedf-by descending charge: YIts properties must; therefore; combine good: resistancei tochemical act-ion and temperature as well vas a'- highmecl'ianical'V strength and' abrasion resistanceV at the-tem peratures involved. Properties of brick used for lining the upperinwall are directed-principally towards exceptionally high-abrasion resistance with but little attentionbothto'V thechemicalf stability and capability off standing-high teme peratures.

Advances made inthe manufacture of refrac tories permit to a great extent the meeting-*of the requirements of three of tl'ieabove mentioned-zones namely,v the hearth, bosh and upper inwalllsectiona The fire brick as now1 producedisi capableof= withstanding both\ tempera-l ture and the`d chemical actioninvolved aslv well.

as abrasion in the upper-inwalL- .Thet'emperae ture: in. the lower partof thefinwalloi a'. con-` temporaryv blast` furnace variesrusually between 2450 and 2300 F. andavery pronounced soften-4` ing of fire-clay brick occurs ata around 220091?. Consequently; `it will? be seen: that. in order' to support the heavy weight'. of the-superimposed lining; the lower portion. offthe linwafllrrnustbe madee excessivelyfthick. Onlyl few." years ago.

InV thev llower inwall", the brickv must'- meet'.

40,- inches..

IInposs-ibility of obtaining the desired prop. erties; by` use .or brick' itself; led blast furnace.v technicians vto provide the additional` required.`

characteristics-.to.thevital parts oi. the furnace by. meanszofzarticially.cooling the lining. Thisx practicebecaniezstandardl as far as the boshand hearthsectionwas concerned andspread: very. widely it'owardslthe lower .portion Vof the inwall.. In designing ablastfurnace, the liningY of boshl sectionsis relieved from any, superimposed..loads,.

solthatithastostand only.` the temperature .and chemicallactioni-off operating: conditions.. Onthis account',. weakeningfinwall Alining ,by placing, in. it.v voluniinoi'is cooling devicesas: usedY in the bosh section cannotlbe tolerated; thougfhcooling` prac-- i-,i'ceused` in the construction ot the latterade-` quately. meets'` the requirements. Present design` oi'the lower'inwa-ll prevents; however., the applicationiotwater cooling. or anyother type off coolingltoithe-lower por-tionL of the'i'nwall to theextent; oi" assuring the desiredf effect.

'IThef-'inwalll lining; whichrbegins.- at the mantle; plate,A is' at; alli times subjected to` com-pression` exberlt'eol7A by many tons: offrbrick superimposed on it." .This pressure must be absorbed by the re sistance of the brickV at` this.level, greatly-sof1 A- substantia-l reductiontened by temperature. of temperature within theY corresponding. areas can-be effected by placinginthe lining. .a suflicient'. number of cooling boxes ot the type used:` in the=boshlsection, but this practice -l'eadstota pronouncedl weakening ofi the lining. v Coolingboxes,- y.vvlflicli are hollow castings4 .with compara-- tively thinfwalls', have a far lower compression.

streirgtlfiA than brick, and' even at a comparatively low-:temperature of their operation are not.

in at position to support` the load normally irn-u posedlion brickwork. Limitations placedl there-- byA on the number of'boXeswhichcan be effec-r tively used per unit of brickwork inthis areaoff the furnace: are too severeto permit a uniform and VreallyD Veicient reduction of the avere-- age-temperature of thelining.

Furthermore, the necessityf'or scattering coo1- i ing boxes throughout the mass o'fbrickworkv in; order to balance the weakening produced by their use,A eapresseseitselfy in localized cooling, simullocalzation. From. observations: of' blast fui-L naces, the wear on the lining is not uniform but is greatly reduced in the areas where heat absorption bythe cooling boxes is rapid enough to keep the temperature below a predetermined level and deeply penetrates the brickwork in the areas between the cooling members, at which point the heat removal is greatly reduced by the insulating effect of the surrounding masonry. Projections and indentations in the lining so formed pronouncedly interfere with a uniform descentl of the charge, and reduce the lining life to that of its weakest part. This effect appears to be the most pronounced around the mantle plate, and the lower portion of the inwall, where the effect of high temperature, high heat, and

abrasion is the greatest and presents the least4 dependable part of blast furnaces, which is, furthermore, the most diicult to repair under operating conditions.

Heavy lining required at the mantle plate by contemporary furnace designs leads also to undesirable conditions in respect to carbon disintegration. Unless refractories used are entirely free from iron inclusions or these inclusions are present in a chemical form preventing their easy reduction, there is always a possibility of carbon disintegration of the brick involved. This phenomenon has received much study in the hands of both practical men and scientists and lwas iinally reduced to a mechanism associated with the reduction of iron oxide to metallic iron oy carbon monoxide. Metallic iron, resulting from decomposition, in its turn acts as a catalyst leading to the decomposition of carbon monoxide to free carbon which precipitates between the individual grains of the brick creating a suicient pressure to completely overcome, or at least greatly decrease, the cohesion among them. As these reactions take place at a temperature much lower than observed at the inside surface of the lining, a critical zone is created within the body of it where the radiation to the outside balances the heat input from the inside, creating a temperature range leading to this decomposition. This zone is usually established at a certain distance below the inside surface of the lining and gradually advances towards the shell with the wear of the inside layers of the brick. On this account, the wear of the lining up to the point of reaching the original decomposition zone is comparatively slow, but, as soon as this brick is consumed, lining falls very rapidly and out of all proportions to its normal Wear.

Necessity of operating the lower inwall under conditions approaching marginal safety requirements expressed itself in the impossibility of using blast furnaces of common design for production of iron alloys requiring `for their manufacture a somewhat higher temperature range, such as spiegel or ferrosilicon with higher contents of the latter element. The effect of practice associated with their melting on the refractory lining of the furnace is quite pronounced. While properly water cooled boshes and hearth are able to withstand it for a considerable length of time, the lower inwall lining is so rapidly and severely affected that switching the burden to the making of these alloys is permissible only in the latest stages of a furnace campaign when the lining is gone far enough to disregard it as an operating factor.

These aspects of furnace design are well known to blast furnace technicians, and many attempts have been made already to remedy the situation in some appropriate manner, among whicha particularly important place is occupied by the socalled thin lining. This lining consisted of only a few layers of bricks applied to a shell, and protected by an artificial cooling of the shell to produce a temperature gradient adequate to cause heat elimination at a rate suifcient for preventing an excessive attack on refractories. Furnaces incorporating the above idea have been builtl and run for a considerable time but with rather indefinite success. vThe chiefdiiiculties associated with this type of lining were principally connected with inadequacy of shell cooling. ,As a general rule, either sprinkling or allowing water to run over the surface of the shell were the vonly means available for heat removal. Thin-lined furnaces'and other installations incorporating the principle of shell cooling from the outside failed; however, in achieving the desired results and led to the return of the presently accepted thick lining.

Furthermore,v any radical changes in thev design of this portion of the furnace cannot be introduced without pronounced objection, because the lines of the furnaces, after the evolution covering centuries, are standardized to the extent that'any modification in them beyond changing an angle of inclination by a very few degrees, cannot be tolerated from the standpoint of eiciency and the large investment involved. On this account, any modifications which might be introduced have to be adopted in connection with existing lines of the,v lining, leaving the design oi the shell alone open to further adjustments.

According to the present invention, theV diiiiculties and inconveniences associated with the present construction of the lower portion of the inwall are eliminated ina simple and effective manner by raising the mantle plate and replacing a portion of the shell lined with the refractories, i. e., the portion extending from the mantle to the jacket of the boshes, with a cooling and reinforcing jacket of a special construction.

Accordingly, it is the general object of the present invention to provide an improved blast furnace constructed in such a manner that the aforementioned difficulties are eliminated, and at the same time, a construction which is strong and rugged and possesses the required characteristics of a good furnace.v

It is another object of the invention to provide an improved blast furnace which is simple and inexpensive in its construction, and, at the same time, efficient and effective in its use.

Y It is a further object of this invention to provide an improved lower inwall for blast furnaces and the like which may be easily and conveniently incorporated with existing blast furnaces at a minimum amount of expense.

It is still another object of this invention to provide an improved cooling and reinforcing jacket for the lining of the lower inwall of blast furnaces and the like. Y

Various other objects and advantages of this invention will be more apparentin the course of the following specification and will be particularly pointed out in the appended claims.`

In the accompanying drawings there is shown, for the purpose of illustration, an embodiment and several modifications thereof which my invention may assume in practice.

, In thesedrawings:

Figure 1 is a vertical sectional view through the side of a blast furnace of the conventional type;

Figure 2 is a similar view ,through the side of a blast furnace constructed in 'accordance with the assassine-rf present invention showing my improved cooling and` reinforcing 1j acket incorporatedl therewith;

Figure13 is a front elevational view of .ai section:` of the improved cooling and reinforcingfj'acket off:- my invention showing the preferred formtofconf" structiom:

Figure 4 is asectionallview taken onlineIV--IV of Figuref.;

Figure 5 is a sectional;view'taken on line,V-V ofFigureB.;

tionaltype blast furnace as presently used. In

sucha construction, there is provided a hearth sectionL 2. having a boshV section` 3 arranged di'- rectly thereabove withbosh plates l arranged in the wallof the furnace'for cooling the same. Di-

rectlyrabove the bosh section 3, there is arranged a. mantle-plate 5 which encircles thev furnace and which is supported by columns E positioned onl the outer side of the furnace in a well known manner. the mantle plate 5, there is positioned a relativelyl thickV lower inwall section 'I having a` series of cooling boxes -arranged in the refractoryv brickwork thereof for cooling the same. 'I-'here is provided a cooling plate 9 which encirclesn the hearth section for cooling the same. In such a conventional construction, the mantle plate islusually located at a point of'about 25 to 30 feet above thebottomof the hearth. This cor'- respon'dsfto a temperature range within the lower inwall sectionfrom about 2250 to 2450`F. which results' in an'excessive softening of the'bricksupporting thev superimposed lining.

According to the' present invention, asshown in Figure`2 of the drawings, which is a vertical sec tion through the wall of my improvedblast fur'- nace; a section similar tothat shown in Figure 1, the hearth section 2EL and the bosh section 3a' are substantially the same as in the conventional type. However, in my construction, the mantle plate-5a is positioned at a point above the lower inwall section 'lEL and is supported as before, by columns 6a. The refractory lining of the lower inwallA section 'la is relatively thin and there is arranged there'around and directly next thereto and extending substantially between the mantle plate-5a and the bosh section 3a, an annular cooling and reinforcing jacket l0. This jacket is preferably supported by suitable means (not shown) carried bythe mantle plate 5a or in any other' suitable manner. There is arranged aroundi the hearth section 3a, a cooling and re'- inforcing jacket I2 similar 'to the jacket Il) which will be described hereafter in detail. In the proposed construction the mantle plate is raised and positionedv at a point of about to 40 feet' above5 the bottom of the hearth,A or, in other words; to the level at which the-refractory lining is lsubjected to 'a' temperature varying from` about Directly above the bosh section' 3 and l() FigureL Gis a cross-sectional view'of. a modified-v formiofconstructionof the jacket as: shown. in.

D; to: 2100? F.. and consequently: disposed intthe:

rangezresulting.l in strength andlre'sistancee ampiy.-

capableltovwithstanditheiattack ofoperating. conl-A diti'onsi for.' a'. considerable.- lengthroff time.: By providingisuch:av construction', itZWilLbeLSeeIn that',

the necessity of providing-1a relatively thiclc walls atl the mantle'. plateasA normally" and: aboveV asla. means fori obtaining the. necessary safety'factorf from? the abrasion resistance standpoint;` is; elimiinated, Vand makeszthe use of cooling.boxesasuperer uous; which', in its turn, .permits .ia i further` thine ning' of; the lining;

It will be seen; that the position of theA mantle'-v f plate in the; proposed. construction: does. notinvolve'. anyIV changes whatsoever ini the inside .lin-. ing. ofthe furnace, for thereason that-the'. con-y touricfthelining isnotzaffectedj by' the.changeszirrfv outside dimensions of Athe 'shell oriinf reducing the@` thickness of the' lining' itself.

Asf hereinb'efore' stated, the cooling. and; rein- -1 forcing: jacket Ii extends substantially from' the mantle'plate ila to the bosh'section- 3&2, andfis-'in-l tendedl to replace the corresponding portion of the shell 'fwithi its thick' lining of.` refractories; afs:

- shown in r the' conventional' furnace. design; This" jacket isf constructed inV such a manner as to have sufcient'strength and to provide a refrac'e' torylining surrounded by it witli suitabl'ere'efsistan'ce to temperature and chemical. action to which this portion ofthe furnace is subjected. The jacket ispreferably constructed froml steel or other metals selected to have suicient strength and formedto coincide with the external' outlines' of this-portionl ofthe furnace shell;

In order to increase the protecting power ofthe relatively thin refractorylining off the lower in wall section la, the jacket Illshould-beconstructedr in such a` manner so asr to assure a uniform abstraction ofheat over the entire areaoff`the2exf--- posed surface so' as to completely eliminate theV deleterious effect of localized cooling as experi'- encedA by theuse of cooling boxes; Accordingly, it is desirable that the jacket lo b constructed so as-to provide therewithin a labyrinthic or`sinuous passageway for conveynig the cooling water or fluid over the entirearea of thejacket.l Such a construction may be provided in a multitude ofl ways; for example, by sealing, at a certain dis-'f tance from the inner jacket plate;` a sheet of steel? or anyother suitablematerial having a thickness suiiicient only' to withstand the pressure of water appliedfor cooling purposesand providing, in the space between the jacket plate and this sheet, a series ofv` baffles to control thecirculationof the water or iiuid'in any desired: manner.

By adjusting the rate 0fl water flow through the jacket, it will baseer; that the coolingeffect exerted on the refractories can beregulated to meet the requirements of melting practice. It will be understood that when" common grades of castiron are made in a blast furnace; acomparativelylow rate of: heat removalY is sufficient to compensate for the heat produced by the charge: By increasing properly theA heat elimination to take care of hotter charges associated with ferroalloys melting, itV will be seen that the lower inwall lining of the furnace is protected from` pre-- mature failure. Accordingly, it will be seen thata furnace constructedin accordance withthe present invention extends the use of a blast fur-f ing of certain ferro-alloys occasionally require'aaf cooling rate to be applied to `furnace refractories which isdiflicult to achieve by means of equipment made of steel. While steel is amply satisfactory from the standpoint of strength, it is well known that this metal has a. somewhat low coefficientV of heat conductivity. When a desired rate of heat abstraction from the exposed surface of the refractory lining exceeds the heat absorbing capacity of a cooling jacket, when made of steel, as proposed, the rate of heat abstraction may be increased by substituting for the steel a metal having a greater coefficient of heat conductivity, such as copper and some of its alloys. f

YIt will' be understood that by providing a thin lining in'tne lower inwall section of the blast furnace, in accordance with the teachings of the present invention, there results a further advantage of preventing to a great extent carbon disintegration of the brick. It is well known that a very considerable dierence between heat conductivities of metal and refractories contracts the zone of temperature at which this phenomenon takes place to a fraction of that observed in the body of a heavy liningand concentrates it at the outer faces of the brick, i. e., the face coming in contact withy the cooling plates. Furthermore, the disintegration zone, once established by the thermal balance, is maintained in the same position instead of being allowed to travel outwardly,

as in the case of the conventional thick linings.

Although many types of cooling and reinforcing jackets are suitable for achieving the objects of my invention, I prefer to use a jacket constructed in a manner as shown in the several embodiments of Figures 3 through 1l of the drawings.V The jacket in each of these embodiments includes a relatively thick arcuated inner plate I3 which is adapted to be disposed directly next to the outer side of the refractory lining of the inner wall section 72t of the furnace, as shown in Figure- 2. It will be understood that the plate I3 reinforces the thin lining of the lower inwall section 1a. The jacket is preferably made in sections with the abutting edges of the plates I3 welded together as at I3a so as to provide an annular arrangement which completely encircles the lower inwall section of the furnace. In the preferred construction, as shown in Figures 3 through of the drawings, there is arranged on the outer side of the arcuated plate I3, a plurality of vertically extending spaced apart rectangular-shaped members Ill having one of their longitudinal edges welded to the plate I3 soV as to provide channels therebetween. The successive members I4 terminate a short distance from the top and bottom of plate I3 so as to provide a continuous sinuous passageway around and between the members I4. There is securely welded to the outer longitudinal edges of the members I4 a relatively thin arcuated plate I5 which corresponds in size to the plate I 3 and is spaced therefrom ,by the members I4. There are welded to the ends of members I4 and the plates I3 and I5, top and bottom plates It and Il, respectively, so as to provide an enclosed structure. It will be understood, as hereinbefore stated, that the jacket is preferably made in sections primarily for the purpose of handling and ease in assembling, and when assembled in place around the outer shell of the inner wall, the edges are secured together preferably by means cf welding or in any other suitable manner. There is provided means, such as cooling'pipes I9 and 20, for conveying the cooling fluid into and out of passageways in each sgction, ,.7 i Y i The construction, as shown in Figure 6 of the drawings, is similar to the preferred construction but diiers therefrom in that the plate I5 is not one continuous plate. In this construction, the passageway formed between each of the vertically extending members I4 is enclosed by a' rectangular-shaped plate 2i, and the edges of each of the plates are successively welded to each and to alternating members I4 as at 22.

In Figure 'i' of the drawings, there is shown another modiiication of the cooling and reinforcing jacket I0 of my invention. In this construction, there is provided the relatively thick heavy plate I3, as before, and on the outer surface thereof there is disposed a plurality of vertically extending'structu'ral members 23 having substantially a U-shaped cross section. The ends of the leg portions of each of the U-shaped members are welded as at 23St to the outer surface of the plate I3 and to the leg of the next succeeding and abutting U-shaped member so asV to provide a series of U-shaped parallel channels 24 between the U-shaped members 23 and the plate I3. A portionof the material of the leg portions 'of each ofthe members 23, at the top and bottom of alternate plates, are cut away as at 25, as shown in Figure 8, and there is arranged between the leg portions and disposed around the cut away portions formed therein, preferably, a channel-like member 26 for interconnecting the channels 24 between successive U-shaped members so as to provide a continuous sinuous passageway on the outer surface of the plate for conveying the cooling fluid therearound. Between the sections of the jacket there is provided, preferably, a plate member Illv which is Welded to the outer surfaces of U-shaped members 23 positioned at adjacent ends of the sections so as to provide a channel 28 between each of the sections.

In Figure 9 of the drawings, .there is shown a slight modification of the construction as shown in Figure 7. In this construction, there is provided a plurality of vertically extending members 29 which are arcuated or substantially open U- shaped'in cross section. They are disposed on the outer side of the plate I3 in side-by-side relationshipwith one of the longitudinal edges thereof welded to the outer surface of the plate with the opposed longitudinal edge welded to the outer side of the next succeeding member 29 so as to provide an irregular-shaped passageway or channel between each of the members 29 and the outer side of the plate I3. A portion of the edge of each of the plate members 29 welded to the plate I3 at the `top and bottom of alternate plates, is cut away as at 30 so as to interconnect the channels whereby a continuous sinuous passageway is formed along the outer side of the plate I3 for conveying the cooling fluid therealong. As before, there is provided preferably a rectangular plate 3| which is welded to the outer sides of the adjacent members 29 on the ends of each of the sections for providingan'enclosed channel at this point.

In the embodiment of my invention, as shown in Figure 1I) of the drawings, there is provided a plurality of vertically extending angle members 32 which are disposed in side-by-side relationship on the outer side of the plate I3. In this modification, the end of one of the legs of each of the members 32 is securely welded to the outer surface of the plate I3 and the edge of the other leg of each of the members is welded to the outer surface of the next succeeding member 32 so as to provide an enclosed channel between two adjacent membersrand the outer side of the plate.`

Assiri therconstructionshown in `Figure 9, faipor- :ition rofithe gleg; .which pis-welded fto fthe plate I 3 vis removed, :from :theitop .and .bottom .of :alternate plates, sons atozinterconnect the channels formed bvthe members 32 whereby 1a continuous lsinuous passageway-pis fprovided along .the outer vside of 'tliezplate J3. f

i'nliigure lll of the rdrawings, there is shown stillanother modified Aferm o f J construction :of fthe :jacket Irl-this constinction, there is provided a .plurality ofvertically extending T-gshapedstruc- :turalzmembers :33 .whichare disposed in .side-by- :side-relationship i. on thev outerside of the plate ,13. .Thezbottom .edge of the upright or verticalportion offeach Aof v'the T-,shaped members :is :welded to the outer surface of the plate i3, andithe r.ad-

1 jacentedgesiof Y,the cross portions;of3the"l'fshaped members tare welded V,to vvthe 'abutting fedgesfof the :cross-*portions'oftad-jacent T-shapedimemhersfpo- `sitioned tto .either .side thereof iso `:as to tprovide :an enclosed :channel vbetween ltwo :succeeding T- .shapedmemberszand the outerside nf the-plate d3. Likewise, Ain this construction, ,'a'iportion of the :upright .portion of the Tlf-shaped :members 333,. at the itop and bottom .of 'alternatefmem'bera js cut away;orzremoved, so :as ito interconnect the channels, thus again yproviding a continuous 'pas- :sagewaypn the `outer-side of the plate. .'Itwill be zunderstood that in all thesemodied construcvtions,.there is provided top v'and bottom fplates, ,lsirnilar to `.plates It and llin thepreferred vconstruction for enclosing the :respectivezzstructures.

the vertical arrangement is the most satisfactory, and practical, because of the ease in fabrication and assembling thereof While the cooling and reinforcing jacket heretofore described is particularly adapted for creating conditions of an adequate heat absorption in the lower inwall portion of the furnace, it will be understood that such a jacket can be used to advantage in any part of the furnace where an eicient and uniform cooling is required, as for example, around the hearth. In fact it is desirable that the cooling and reinforcing jacket of the construction above described be used as the cooling jacket l2 for the hearth, as shown in Figure 2 of the drawings.

While I have shown and described several specic embodiments of my invention, it will be understood that these embodiments are merely for the purpose of illustration and description and that various other forms may be devised within the scope of my invention, as dened in the appended claims.

I claim:

1. A jacket for cooling and reinforcing the lower inwall section of blast furnaces and the like comprising a plurality of arcuate-shaped sections continuously arranged around the furnace wall having their edges welded to each other so as to provide an annular arrangement, each of said sections consisting of an arcuate-shaped relatively thick metallic inner plate which is -adapted to'rbe vdisposed ldirectly next to the-furnace wall, a plurality -of members arranged on the outer surface of said plate sonas ltoprovide `anon-tinuous sinuousfpassageway-along the outer .surface rof :said plate, and means for introducing `Aa .cooling fluid into said passageway for cooling saidplate.

:A 'jacket for cooling and reinforcing vthe l ;.lower.inwall section of blast furnaces and the like .comprisingapluralityfof sections continuously arranged ;,around vthe furnace wall having their edgeswelded vto each `other so as to provide an annulargarrangementeach of said sections consistinglof an arcuatefshaped relatively thick inner `plate whichxis adapted =to be disposed directly next to the ffurnace wall, a plurality of substan- `tially parallel members disposed vertically on the ".outergsurface,ofsaid Jplate fand securely welded xrectly -neXt uto `the .furnace wall, a lplurality of spaced apart parallel,rectangulareshaped r`metal- `licmembers,disposed vertically on the outer surface of said plate having their edges welded to the outer surface thereof so as to provide a channel successively between each of them with successive members terminating short of the extreme bottom and top of said plate so as to provide a continuous sinuous passageway along the outer surface of said plate, an arcuate-shaped outer plate substantially conforming in size to said first mentioned plate welded to the outer edges of said rectangular members so as to be spaced from said first mentioned plate and to enclose the channels between said parallel members, top and bottom plates welded to both of said innerand outer plates so as to provide an enclosed structure, and

means for introducing a cooling fluid into said continuous passageway for cooling said first mentioned plate.

4.'A jacket for cooling and reinforcing the lower inwall section of blast furnaces and the like comprising a plurality of arcuate-shaped sections continuously arranged around the furnace wall having their edges welded to each other so as to provide an annular arrangement, each of said sections consisting of an arcuate-shaped relatively thick metallic inner plate which is adapted to be disposed directly next to the furnace wall, a plurality of parallel U-shaped channel-like members disposed vertically on the outer surface of said plate with the ends of the leg portions of each of said U-shaped members abutting each other and securely welded to said plate and to each other successively therearound so as to provide `an enclosed channel between each of said U-shaped members and said plate, and means structure, and meansrforintroducing a cooling fluid into said passageway for cooling said first mentioned plate.

5. A jacket for cooling and reinforcing the lower inwall section of blast furnaces and the like comprising a plurality of arcuate-shaped sections continuously arranged around the furnace wall having their edges `welded to each other so as to provide an annular arrangement, each of said sections consisting of an arcuate-shaped relatively thick metallic inner plate which is adapted to'be disposed directly next to the furnace wall, a plurality of parallel channel-like members having an arcuate-shaped cross section disposed vertically on the outer surface of said plate, one of. the longitudinal edges of each of said members securely Welded to the outer surface of said plate with the opposed longitudinal edgefof each of them securely welded to the outer side of the next successive member around the plate so asl to provide an enclosed channel between each of said members and said plate, each of said channel-like members having a portion removed therefrom alternately at the top and bottom of successive members at a point adjacent the edge Welded to the plate so as to interconnect the channels formed thereby whereby a continuous sinuous passageway is provided along the outer surface of said plate, top and bottom plates welded to` the ends of said channel-like members and said plate so as to provide an enclosed structure, and means for introducing a cooling uid into said passageway for cooling said plate.

6. A furnace of the class described including a hearth having a bosh section arranged thereabove, a relatively thin lower inwall section made of a refractory material arranged above said bosh section, a mantle arranged around said furnace at a point immediately above said lower inwall section, and a cooling and reinforcing jacket consisting of a relatively thick metallic plate arranged peripherally around and directly next to the thin refractory lower inwall section of said furnace so as to comptely encircle the same and extending substantially between said mantle and said bosh section, and means arranged on the outer side of said plate forming sinuous passageways for continuously conveying a cooling fluid around the outer surface thereof for cooling the same.

7. A furnace of the class described including a hearth having a bosh section arranged thereabove, a relatively thin lower inwall section made of a refractory material arranged above said bosh section, a mantle arranged around said furnace at a point immediately above said lowel inwall section, and a cooling and reinforcing jacket consisting of relatively thick metallic plates integrally joined together arranged peripherally around and directly next to the thin refractory lower inwall section of said furnace so as to completely encircle the same and extending substantially between said mantle and said bosh section, and means arranged on the outer side of said plates forming sinuous passageways for continuously conveying a cooling duid around the outer surface Ythereof for cooling the same.

GEORGE A. WHI'IEHURST.

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