US968238A - Metallurgical heating. - Google Patents

Description

B. E. ELDRED.

METALLUBGIGAL HEATING. APPLIOATION Hman 1120.22, 1908. l 958,238, Patented Aug.23,1910.`

Witwe/.saco W B. E. ELDR'ED.. METALLURGIGAL HEATING.

APPLIGATION HLM) 11110.22, 190s.

Patented Aug. 23, 1910.

3 SHEETS-SHEET 2.

/jranlireg B. E.' ELDRED. METALLURGIGAL HEATING.

APPLIOATION Hum 1120.122, 1908.

Patented Allg. 23, 1910.

3 SHEETS-'snm a.

- ww? Mawzam STATES, I' rl'-.'I'IE1\IT zonuren.

BYRON E. Ernani), or. iaRoNxvILLE, NEWvonK.

MTALLURGIGAL HEA'rING.

To all whom tt may concern:

Be it known that I, BYRON E. ELDRED, a citizen of the United States, residing at Bronxville, in the county of- Westchester and State of New York, have invented certain new and useful Improvements in M etallurgical Heating, of which the following 1s a specification. Y

Thisv invention relates toy metallurgical lo heating; and it comprises a. method of heating and treating materials on the hearth of a'reversing furnace by, means of-a regeneratively supplied flame burningnext the roof of the hearth, said flame .being spaced away and separated -from 'the hearth andthe materials thereupon bya heated body of .unburning frases next such hearth and materials, said bodyof unburning gases being burned beyond the hearth chamber-to vfurnish heat to heat-recovering devices; and it also comprises certain combinations of apparatus elements useful in performing such process, such -cOmbnation comprising a hearth chamber provided with heat-recovering devices at each end together with various conduits, valves and by-pass means whereby air and a combustible gas may be transmitted through a pair of regenerative devices in the heat-deliveringV phase at on.'

rents, one of said. currentsbeing transmitted through the hearthchambertoward the regenerative devices in'heat-absorbing phase at the other end of the furnace while the other current is divided, one portion being sent through the furnace chamber next the roof to forma flaming stratum thereagainst while the other portion is by-passed around the furnace chamber to a chamber connected with the heat-absorbing devices to enter into combustion with the art of the said first *current not entering 111to .combustion with the said'first portion of'the second-current;

all as more fully hereinafter set forth v and as claimed.

furnace of the Siemens type is particularly adapted to the'v production of very high generators in heat-absorbing phase, while end of the furnace to form two heated cur- The ordinary open-hearth or reversing Specicaton of Letters Patent. v Patented Aug, 23, 1910,v `Application filed December 22, 1908.

serial- No. 468,827'.A

Afrom time to 'time the direction of the flow' through the furnace chambers is reversed to bring each pair of regenerators alternately in heat-absorbing and-heat-delivering phase. With this method 0f operation it is 60 obvious that the heat ordinarily carried away by the lproducts of `combustion is in large part restored to .the flame and that after a few alternations or passes, the flame temperature of even sucha poor vgas as proi ducer gas can be steppedAup to almost any point desired shortof `the dissociating temperature of carbon dioxid. For many purposes however, and^particularly for heat- 111g oxidizable metals, such as steel, vtle de- 70 scribed process suffers from many defects'. The flame and flame gases are in Contact Vwith the material to be heated, and whether the flame be run with an excess-of air, as is ordinarily the case, or reducing, the metal 75 1s more orv less oxidized. Both the oxygen of the air and the carbon dioxid of products of combustion will of course oxidize hot steel or other ferrous metals, and vthough this oxid may be again reduced'where the ame 80 1s run reducing, this latter action is apt to be lrregular. In the case of billets and other large steel objects, the oxidation. by oxygen orcarbon dioxid, though asource of loss, may not be of great'importance, but 85 where comparatively thin objects, such as plates or sheets, are heated, or where a true metallic surface is required on the steel, as in certain recent methods of making clad metals, this 'oxidation is a matter of consid- 90 erable disadvantage. And while, 'as stated, the open hearth furnace maybe run reducing, this ris doneat a sacrifice of temperature and in any event does not preclude oxidation by Very hot flame vis maintained. Ordinarily, moreover, the flame is streaked and stratified, so that there is always danger of strata vof intensely hot air coming into contact with the materials being heated. i In the presentv invention, the described process is modified iny such manner as to produce a current or flowing 'stratum of gases between vthe materials being heated or treated and the flaming current of burning'105 gases, the flame being produced next the roof of the hearth chamber'in such manner as to radiate heat downward upon the hearth while spaced'away and separated therefrom by non-Earning gases. The spacing stratum, 110

carbon dioxid as long asany i water gas, blue gas,. natura the spacing stratum, steelbillets an maybe `bathes, covers and andoxidized to produce/)desirable roducts,

ecorated porcelain or glass containing or A with delicate colorsv may bev heated, etc.

Using a reducing gas, such as roducer gas, g etas p .thelike heatedwithout oxidation; iron ore reduced, etc. I shall however here the invention as more particularly may be describe Y ada ted for heating steel objectsr without hearth -chamber to oxi ation.

Whatever the specific modification einployed, the gaseous current coming from one ot regenerator is passed thro h the hearth chamber toa combustion chaiiiicr above,'or in proximity to, the cool regenerators while the gaseous current, whether. air or com- -bustible gas, coming from the other hot-regxenerator is divided into'. two fractions one action being sent alon the roof of the a flame with the aid ofthe first-named current while the current. `In other words,

' is performedV beyond4 the hearth chamber. the regenerativeAr devices tem-1 in the specific in hereinpreferred, steel billets or like steel artithrough a hot regenerator A work is caused checkerwoik is ,divided into two fractions j and one fraction is sent along the roof of the through the; thin other fraction is by-passed around the hearth chamber to said combustion chamber and there completes the combustion of said first instead of all the combustion being performed in the hearth chamber in 'contact with, or in proximity to,

,the materials being treated, only a portion is performed therein, the flame being spaced from such away materials, While the residue vbefore in porarilyfinfheat' #uppphasef For instance,

ication of this invention cles are placed on thehearth of a'furnace chamber and a current of producer eneckerto dow thereover. vA current of lair entering through a similar hot furnace where it burns the underlying current ofproducer gas at its upper ace, producing a llame stratum hugging1 the roof and radiat' .heat down upon t e billets burning next t e hearth. The remaining fraction of the hot air is by-passed around the furnace chamber and completes the combustion of the gas in a combustion chamber above, or connected with, regenera- ,tors in heating-up hase, or in the regenerators themselves. he same procedure iay be employed in makingiron or steel direct from powdered or briqueted ore on the -f..hearth, with or without. admixed carbon,

L6&5-` though here thereducing gas stratum instratum of hot but u n-v current isv sent through the furnace next the hearth while the current of hot gas is subdivided, o'nefraction being sent along the 'roof toproduce flame while the remaining fraction is' bypassed around the hearth chamber to produce combustion .with the hot air .and heat regenerators.

In the accompanying illustration I have shown, more or less diagrammatically, certain novel organizations'of apparatus elements useful in performing .the described process.

In this showing :-Figure 1 is a transverse vertical section on line'C-(l, Fig. 2, showing hearth, hearth chamber and twin regen.- erators at either side;A Fig. -2 is a view, partly in horizontal section andA partly .in plan on line BB, F' 1 and, F'1g. 3 is a detail view in .vertica section,l along .line A--A, Fig. 2.

Referring first .to Fig. 1, 1 is a hearth between side-walls 2 and 3, shown. as ,perforated at 4 and 5, and covered by reverberatory roof 6 of the usual refractory materials. Doors 7 allow access to the hearth. On each side of the hearth is a pair generative devices, those at the left marked 8 and 9 and those at the right marked 10 and`11, each being filled with the usual refractory the diagrammaticall shown checkerwork. Space isleft above e refractory materials in each regenerator to form a roomy combus'tion chamber. vBetween 8 and 9, is a hollow wall, 12 through which a suitable damper 13, can be elevated by any suitable mechanism (not shown). h Depending through the roof of the regenerator chambers 'isf'another damper 14, which can be raised ,and lowered by hoist' means 15. The re enerator chambers at t similar y provided with separatin elevating damper 17 ,.'depen and hoisting means 19. Over t eregenera# tor nearest the hearth on "the left isa false' roof or horizontal artition 20, affording a 'flue or passage 21 tween it and the roof proper. Over the regenerator nearest the Piercing the roof (6) materials or bricks in e right arewall 16,. amper 18.

hearth on the right is a similar partition 22' l 24 and communicating'with fuel supply pipe 26.

merely a shielding and heaty iop bersabove the severa-l checkerworks and.A

communicate .with by-pass vflue 31 (see Fig.

vice 32 at each end, shownin4 more detail seat at 34 and the port adapted upon lowering to shut off, more or less llow through 2). f This flue is provided with a valve des' in Fig.f:3. 'Damper 33, shown as lifted, is

opening to the chamber next the hearth. Beyond it is a simple damper 35 adaptedto control flow through the port opening to the chamber farther away from the hearth. The damprs and other elements requiring-A` 4cooling may be Water cooledin theusual manner but for simplicity, of illustration, the details of such cooling are omitted from the showing. Stack 36, air -valve 37, gas conduit 38, gas valve 39, and flap valves 407 A and 41 are of the construction usual with reversing furnaces. Flues 42, 43, 44 and 45 are also as usual. Considering regenerators 8 and 9 as in heat-delivering phase and 9 as heating gas, gas from 38, valves 39 and 41 being suitably set, hows through 43 to checker 9, while air passes valve 37, 40 being suitably set, and enters 8 through 42.

Y Products of combustion from 10 and 11 pass out through 44 and 45, and,- valves 40 and 41 being suitably set, are discharged through stack 36. When 8 and 9 are in heat-absorbing phase, the'circulatioii is reversed.

Returning to the furnace proper and considering the'flow to be from left to right, that is, with 8 and 9' in heat-delivering phase, gas passes up through 9 and is intensely heated. Valve 13 being elevated and port 28 closed, the gas flows to the right through 4 and port 46 between partition 20 and' wall 2 and through the hearth chamber, forming through' -4 a quiet 'stream slowly crossing the hearth, gaining access to the combustion chambers at the right through 5 and port 47, formed between partition 22 and wall 3. Air ows up 4through 48 in, an intensely heated state. Part is bypassed through port 27, iue 31and ports 29 and 30 to burn gas in the combustion chambers above 10 and 11, while another portion -is sent along roof 6 through passage V `21 to form asheet of flame in contact with protective layer. .ducer-gas, water gas-or blue gas, it is Vfree fromany oxidizing tendencies while, on the other hand, it will reduce any oxid which l. may be already present on such objects as Y combustionby the hot air from 21,- producsteel billets, molten copper or other'metallic bodies. IPortsg4`ins1e that the current of gas next the hearth shall be slow and com.v

'.paratively quiet. The upper layers ofgas iowing' through 46 are brought intoiintense ing an intensely hot lamen'ext the reverberf atory roof whence heat radiates downward l through the underlying layers of unburning 24 delivering a fuel high in carbon may be used to add to the radiating effect The reverberatory roof may be of" any refractory, vheat-radiating 'material' such as lirecl ay, magnesia,'chromit'e, etc., capable of withstanding high temperatures and of radi- A of air going through 21 may becontrolled. The flame and unburned gas leaving the fhearth'chamber-23, 47 and 5 meet a further supply of by-passed air entering the combustion chambers through 29 and 30 and combustion is completed in these chambers and in the connecting checkers, heating the checkers.. The products of combustion from the checkers pass ofi' to stack 36 as already described. I

It -willbe observed't-hat in the described method .of operation, regenerativelyheated gas and air are burned together, part ofthe combustion being effected within the furhace chamber to forma. discrete layer of flame spacedaway .fromthefmaterial tobe heatedby a' layer ofunburning gas and radiating heat to such material therethrough while the residue ofthe combustion is effected beyod the furnace chambers to heat the regenerators for.4 the next'pass or phase. The relative thickness of the flame layer and the layer of unburning gas may be as desired, but enough gas should be'next the material to be 'heated to shield it from direct l contact lwith the .flame the amount of combustion in the furnace chamber and in the combustion chambers -gas upon the objects upon' the hearth. Pipe I The ratio between willsvarycorrespondingly. VV'hen checkers 8 and 9 become cooled and 10' and 11 heated, the direction'of flowmay propriate manipulation of the valves.

When it is desired to heat reducible materials such as oxids usedin decorating china,

be reversed byl ap# porcelain, etc., or to oxidize such materials as sulfid ores,- gas is sent .through 8 and air through 9 instead of the reverse. This directs'a current of hotair through 4, next' the v materials on the hearth, and through 46. A portion of the gas isby-passed through27, 31, 29 andv30' to burn with'the air beyond Athe hearth chamber while another portion is sent through 21 to form a sheet of flame-next Y the reverberatory roof as before.' Oil, etc.,

izo

from v24'm'ay. also be used.A In this method of operating, thel materials on the hearth are shielded from the direct action of the flame or flame gases by a-layer of air.

Using a gas layer next the hearth, iron ores may be readil -reduced to form' iron and steel direct, being briqueted if desired. In forming steel, the necessary amount of carbon may be admixed with the ore.v Orcs of other reducible,'alloying metals mayalso be admixed with the iron ore to form alloy steels. Ores of iron' are not reduced when the ratio of carbon dioxid to carbon monoxid in the bathing gas mass increases above a certain amount while at the same time a high temperature is required, particularly plete combustion in the l devices.

the stated method however, the iron ore isl in contact only with a gas having a minimum percentage of carbon dloxld, the amount incident to the formation of pro- 'ducer gas and the like, While the furnace temperature may be stepped up as high as desired, even to the melting point of Wrought iron, by the use of the`regenerative And there is no flame in contact with the ore to burn out admixed carbon as in prior steel making methods dealing with 4 fine ores. In the present embodiment of this invention, however, the method and f apparatus described arev regarded as more t ing particularly adapted to heating metal Lobv jects, such as steel billets'and plates,- under preclusion of oxidation. In many arts it is desirable to raise steel to high-temperatures, or even to meltit, Without oxidation; both to avoid Waste of metal and t-o avoid changes in composition. In heating alloy steels, for instance, for rolling, casting and other oper.- ations,it is highly desirable to avoid burnout such oxidizable constituents Y' as nickel, cobalt, chromium, vanadium, vtitanium, manganese,.carbon, -etc., and for .such purposes this invention .ishighly usefulas offering any degree of. temperature desired Withoutf actual contact of Vthe Hams, or of oxidizing gases, wlith the material to be heated.

. What -I claim isz- 1. The process of heating passing a current of air and a current of combusti-ble gas through heated regenerative devices to heat the same, passing one such current through a reverberatory roofed hearth chamber in contact with materials on the hearth, producing combustion in an overlying layer of such current next the reverber-Y atory-roof,by a portionof theother current,

'supplying the residue of said other current to the gas mass leavingthe furnace chamber yto complete the combustion and passing the products of such complete combustion through suitable regeneratlve devices to heat the same. A Y

which comprises' 2. The process of. heating which comprises heating air and combustible gas in re enerative devices, passing a current of t e hot gas over and past anl article to be heated .maintained on the hearth of a suitable reverberatory-roofed chamber, producing combustion of an overlying layer of said gas next said roof by a portion of the hot-air, supplying the residue of the hot air to the gas mass leaving the chamberv to complete the combustion and'passing the products of such complete combustion through suitable' regenerative devices to heat the same.

` The process of heating iron or steel articles which comprises maintaining such articles on` the hearth of a reverberatoryv 'laA 'roofed furnace chamber, passing a current of regeneratively heated vcombustible gas` in an unburning condition over and incontact with said articles, producing combustion of an overlying layer of said currentnext the furnace roof by' a portionl of regenera-A tively heated air, completing the Acombustion of the gas beyond the furnace chamber by another portion of redeneratively heated air;

combustion through suitable regenerative devices Vto heat the same.

4. The process of heating and treating I. i

materials whichfcomprises maintaining suc materials on the' hearth of a regenerative furnace, producing a flowing heated unburning gaseous la er next to and-bathing such materials, pro ucing a layer of flame above such gaseous layer and radiating heat therethrough to such materials, uniting the layers beyond the furnace :chamber and pro-J ducing complete combustion, and passing the 'products of such complete combustion throughregenerators to the furnace.

5. The process of heating andl treatin materials which comprises maintaining suc materials on the hearth of a regenerative -l furnace, producing a flowing layerof unburning hot combustible gas next to and bathing such materials, producing a layer' of Hameabove such first la er radiating heat therethrough,uniting the ayers beyond the furnace chamber and producing complete combustion, and passing the products of suchV ,complete combustion through regenerators of the furnace. l

6. The process of heating and treating materials which comprises passing a current of fair and acurrent of .combustible gas through heatedv regenerative devices to heat 'the same, passing one suchcurrent through a'reverberatory-roofed furnace chamber in' contact with materials on the hearth,=pro ducinfg combustion -in an overlying layer of such current spaced-awayfroms'uch ma terials and nextthe roof by -a of the. i, l

other current,1supplying a luminescent comi bustible' to the burninge layer .to increase'u ,f I. t i nf radiation, supplying -gresidue of Asuch z ist and passing the products of such complete other current to the gas mass leaving the furnace chamber to complete combustion,

and passing the`products of such complete combustion through suitable regenerative devices to heat the same.

7. The process of heating and treating l materials which comprises heating air and combustible gas in regenerative devices, passing a current of the hot. gas through a reverberatory-roofed hearth chamber in vcontact with materials on the hearth, producing combustion in an overlying layer of such, current spaced away from such materials and next the `roofbyma portion of thehot air, supplying a luminescent combustible to the burning layer to increase radiation, supplying the residue of the hot air to the gas 'mass leaving the hearth chambery to coinplete combustion, and passing the products of such complete combustion through suitable regenerative devices to heat the same.

l 8,. The process of heating iron and steel under preclusion and removal of oxidation which comprises maintaining the `metal on the hearth of a reverberatory-roofed regenerative furnace, transmitting a current of regeneratively heated Y, combustible gas through the. hearth chamber, combustion f the underlying layer of such currentvbeing avoided, producir-1' combustion in an overlying layer space away from such metal and next the roof by a portion lof theregeneratively heated air, supplyi -a luminesc ent combustible to the burning layer to increase radiation, supplying the residue of the regenerativel-y' heated air to the gas mass leaving the hearth chamber to complete kcombustion and passing the products of such complete combustion through suitable' regenerative devices to heat the same.V

9. lThe. process of heating iron or-` steel `articles .which comprises maintaining such articles onv the. heart-h of a reverberatoryroofed furnace chamber, maintaining anatmosphere of unburning combustible gas in contact Withgthe articles on the hearth, producing an intensely-hot flame from heated A gas and heated air'next the roof of such `materials in regenerative chamber and spaced away from .such artiducing a burning layer of ame aboye such v"current and nextthe roof of such hearth chamber,- heat being supplied to the' inflowing combustible gases and to' the air feeding vices to heat the same.

chamber. y

and treating such flame from the regenerative devices of,l

Vsuch furnace and the outtlowing combustible gases being burned beyond the -furnace' chamber by regeneratively heated air to supi.

ply heat to regenerative devices.

11. The process of heating and treating materials in a regenerative furnace .which hearthof such a furnace, heating a current of air and a current of gas inthe regenerative devices of such furnace, transmitting a portion of .one such heated current'across the hearth and in contact with the materials as a slowly flowing quiet stream, transmitting the residue -of such' currentl above such stream as an overlylng flowing stratum, producing combustion of the upper layer of such stratum next the roof of the hearth Jchamber bya portion of the other heated current, by-passing the residue of such other current around the hearth chamber and unitingit with the gas mass leaving such chamber to produce complete combustion, and transmitting the products of such com-v plete combustion through regenerative der" 12. The vprocess of heating and treating materials .which comprisesV maintaining such materials on the hearth of a regeneratively supplied furnace having a "rever' anunburning gaseous stratum covering and vcomprises maintaining such materials on the protecting suchfmaterials and producing a-i regeneratively supplied flame of intense temperature next the reverberatory roof above such unburning stratum and inv radiant re-v lation to such materials.

13. A metallurgical Afurnace comprising a i -reverberatory roofed hearth chamber provided with regenerative 'devices,`mean sfor ,transmitting a current o'f hot gas from a regenerator in heat-delivering phase through such chamber. and next the hearth, means' for delivering aportion of hot'air from a regenerator in heat-delivering phase next the roof of such chamber to produce an'overlyingl llame and means for delivering the residue of such hot air beyond the furnace chamberv to the gas mass flowing from such 14. A metallurgicalfurnace comprising a .-reverberatory roofed hearth g chamber provided wlth regenerative devices, means for transmitting a current of hot gas from a regenerator in heat-delivering phase through such chamber and next the hearth, means for delivering a portion'of hot air from a regenerator in heat-delivering phase next the roof of such chamber to. produce an. overlyingflame, .means for dellvering a portion of luminescent-=fuel to such flame, and means.

for delivering the residue of such hotairv beyond the furnace chamber to the flowin from such chamber. 4

15. Anfietallurgical furnace comprising a4 gas mass iso i 95 beratory-roofed 'hearthchamben producing i generators reverberapry roofed hearth chamber, a pair ofl re enerators at each side of said hearth cham r, valved'by-pass means connecting `the two vsets of regenerators around the hearthV chamber and valve means opening and closing communication between the reand the other in controllable communication therewith near the roof of such chamber, and v alved bypass means controllably connecting -said ot of each pair to any desired de- -gree at points near the roof of such chamber.

er regenerators around the `furnace chamber. e

' 17. metallurgical furnace comprising a reverberatory roofed hearth chamber, a pair of re enerators atl each side of said hearth cham r and "under the sameroof, a horizontal partition over the regenerator next the hearth chamber on each side and below the main roofwith a conduit therebetween, a Valve adapted to controlcommunication between the further regenerator on each side and the corresponding conduit, and yalved by a pass means between such further regenerators and around the hearth chamber. In testimony whereof, I aliix my signature in the presence'of witnesses.

BYRON E. ELDRED.

Witnesses:

K. P. MGELROY, LEWIS T.,KNox.

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