US1798618A - Open-hearth furnace - Google Patents

Description

mh 9 s. H. M KEE 1,798,618

' OPEN HEARTH FURNACE F'i'led June 24, 1921 2 Sheets-Sheet 1 IN VEN TOR.

A TTORNEYS M rch 31, 1 3 s. H. MCKEE I 1,798,618

OPEN HEARTH FURNACE Filed June 24, 1921 2 Sheets-Sheet 2 I N VEN TOR.

Q k ATTORNEYJ Patented Mar. 31, 1931 UNITED STATES PATENT OFFEQE OPEN-HEARTH FURNACE Application filed June 24,

r The general construction of the'modern open hearth steel furnace is of course well known, such furnace comprising a rectangular box-like structure enclosing a shallow e hearth, upon which the material entering into the manufacture of steel is melted and refined, the heat necessary to the operation being supplied by a flame playing over such hearth. Such flame is usually produced by 16 the combustion of gaseous fuel which, together with the air necessary to support combustion, is supplied through large ducts located at either end of the furnace. WVhere such fuel is producer gas, both air and gas are pre-heated, while if coke-oven gas or natural gas is used the air only is pre-heated. In the typical furnace three vertical ducts are constructed in the brick work at each end, the central duct discharging into a hor- 99 izontal nozzle, known as the gas port, through which the heated gas, where producer gas is employed as the fuel, is forced into the furnace, while the two outer ducts are known as the air uptakes since they discharge 55 pro-heated air into the upper portion of the furnace Such air and the gas meet at the nose of the gas port and produces a flame that passes across the furnace, the products of combustion being drawn out through the openings in the opposite end, which, as indicated, are identical in size, shape and disposition to the openings through which the air and gas are thus supplied. After a suitable period of time the process is reversed, 355 the air and-gas then entering the furnace through the openings by which the products of combustion previously were removed, and such products being carried off through the openings by which the air and gas previous- 49 ly entered.

Considerable difficulty is experienced in such typical furnace in obtaining an intimate mixture of the gas and air so as to insure complete combustion, this difiiculty bei f'? ing largely attributable to the fact that the ducts and passages in question at the respective ends of the furnace have to serve a dual function, as just described. The object of the present invention, accordingly is so to 39 arrange and construct these ducts and pas- 1921. Serial No. 479,995.

sages as to insure the proper mixture of fuel and air, whether such fuel be the relatively dilute producer gas, or the richer coke-oven, or natural gas. At the same time, the ducts and passages are left unobstructed for the discharge of the products of combustion when the operation of the furnace is reversed.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims, the annexed drawings and the following description setting forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but several of the various mechanical forms in which the principle of the invention may be used.

In said annexed drawings Fig. 1 is an approximately horizontal section of one end ofone form of furnace, particularly adapted for use with producer gas, and embodying my present improvements; Fig. 2 is a central vertical section of the same, as indicated by the line 22, Fig. 1; and Fig. 3 is a vertical transverse section thereof taken on the plane indicated by the lines 33, Figs. 1 and 2; while Figs. 4, 5 and 6 are sectional views corresponding with Figs. 1, 2 and 3, respectively, but showing a as modification in construction whereby the furnace is adapted for use with coke-oven gas, natural gas or like richer gas.

The construction of the furnace proper, illustrated in the several figures of the drawings, deviates but little from the typical design previously referred to. Thus, in both constructional forms, that of Figs. 1,2 and 8, as well as that of Figs. 4, 5 and 6, the usual air uptakes 4 are retained, such uptakes dis charging through passages 5 and 6, as shown in Figs. 1, 2 and 3, and through passages 12 and 14, as shown in Figs. 4, 5 and 6, into the adjacent end of furnace chamber 8; while 95 the usual gas uptakes or supply pipes are located between passages. It is principally in the construction of the first-mentioned passages that my present improved, design differs from the typical construction, and that the two modified forms of 'my furnace differ from each other.

Referring first of all to the form designed more particularly for use with producer or like dilute gaseous fuel, shown in Figs. 1, 2 and 3, the port 2, through which fuel is discharged, inclines in .a downwardly direction from the'upper end of gas uptake 1 to the furnace chamber 3. The passages 5 that lead from the air upta-kes 4 to such furnace chamber lie on each side of said port 2, each such passage being divided in its forward portion into two sub-passages or ducts 6, by a short longitudinally extending vertical partition 7. In the portion of passage 5 to the rear of such partition '7 Iprovide. a-deflector 8, preferably pivot'all y attached at its one end to the adjacent sidewall of the furnace, which is cut away to provide a recess 9 into which such deflector may move when desired, and thus entirely clear the passage in question. In this position ofthe deflector, indicated in dotted outline in Fig, 1, the passage is left undisturbed, save by partition 7 for the discharge of'the products of combustion, andthe subpassages 6, it will'b'e understood, are, in their combined cross-section, entirely adequate to care for the proportion of such gases which can escape by the corresponding air uptake 4.

However, in the operation of the furnace end for the supply. of fuel to chamber 8, the deflectors8 are swung out into approximately the positions shown in full line in Fig. 1, with the result that the air supplied through the uptakes 4 is practically all. diverted into the sub-passage 6 lying directly alongside gas port 2, Consequently, the greatest rush of the air, as it is dischargedinto the chamber 3, is immediately surrounding the exit end of the port, and the gas dischargedfrom the latter is very-thoroughly intermixedwith such air-before the mixture has an opportunity to expandand spread out in the furnace chamber. By the means just described, I am accordingly able, to avoidthe fioodingof the furnace with unmixed air, and at the same time the tendency of the air to follow along the side walls or roof of the furnace without mixing with the gas is overcome.

In the formof construction shown inFigs.

4, 5 and 6-, there isshown, first of all, a modification in the gas port, in that the gas is here supplied, not through uptake 1. but. through one or more smaller ducts 10 that enter the furnace through itsadiacentendwall 1I1ClGX tend longitudinally and in a general clownwardly directiontowards furnacechamber 3. Said ducts are preferably embedded in a mass of masonry llto protect :them from ,the high temperatures involved. It will'be understood that in the case in hand additional preheated air will be.suppliedfthrough uptake 1, as well s th oug jl pt kes is nc' h rgas, supplied through said ducts 10'1s soinuch-riclierthan producer gas that a further amount of air is desirable to produce a proper combustible mixture. The arrangement of the horizontal passages 12 is practically the same in this construction as in previously described one, with the exception that uptake 1, as well as uptakes 4, communicate freely therewith. Furthermore, thepartitions .13 that: sub-divide the front portions of such horizontal passages, have their inwardly directed faces inclined so that the corresponding sub-passages 14 are ofsmaller cross-section at their front ends. Accordingly, when deflectors 15, corresponding with deflector 8, are swung into the position shown in full line in Fig. 4 all o-f-the air supplied through the several u takes is diverted or caused to flow into.t1e furnace chambercloscly surrounding thedischarge ends of the fuel supply ducts 10 that here correspond with the'gas port.

The same advantageous resultsfollow from the use of the adjustable deflectorin the air ducts or'passages, in the caseof this last-described construction, as in thefirst.

It will be understood that my improved arrangement'of fuel and air=supply passages and-controlling means therefor maybe employed in any furnace of the general type of anopen hearth-furnace, where the ignited combustible mixture is discharged horizontally into thefurnace chamber over the material to be heated; although certain features: are of particularjutilitywhere the same passages are at one time'e-mployed for the supply of fuel'and atanother time for'the discharge of the. products of combustion.

Itwill be also understood that the fuel, in addition to the particular gases hereinbefore referred to, may be any of theother available fuel gases, or it -may consist ofoil, tar," powdered coal, etc.- The manner in which any such particular fuel willbe supplied'is sufficiently indicated by the two typical constructions already setfforth. It may further be noted in'this connection, that a relatively dilute fuel, such as producer gas, may enter the furnace inone of-the so-called air-ups takes, instead of'the as-uptake proper, and an intimate mixture of such fuel and air still secured by reason of the action ofthe deflectors. The manner in which thefuel and air are supplied to the furnace, whether under natural stackidraft, orunder positive pressure (as forced draft), is of'course a;matter of indifference.

The deflectors may be made of any-suit able heat-resisting material and maybew-ater -cooledif.desired,as need notbe explained in detail. It has alsobeen considered unnecessary for the purpose of this specification to show in detail the operating means for said deflectors, but it will sufliceto. state that they may swingfrom one position to the othereither manuallyor by power, and that such?- operation may be either singly-=or-- in pairs, or tlmse at one end may be connected with those at the other, so that one set will open as the other closes, and vice versa.

In conclusion it may be noted that when the operation of the furnace is reversed, not only are the deflectors swung out of the path of the products of combustion through the passages on each side of the fuel port, but that where the latter is of the form shown in Figs. 1, 2 and 3, it also serves as an exit passage for such products. Moreover, in both forms of construction the space above the discharge end of the fuel port not only affords additional opportunity for the escape of the products of combustion, but during operation as a burner the air supplied through the lateral ducts is caused to flow over, as well as alongside the port by the action of the detier-tors.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means he employed.

I therefore particularly point out and distinctly claim as my invention 1. In a metallurgical furnace, a centrally located gas inlet, and air passages located laterally thereof, in each end of the furnace, said passages each containing a longitudinal partition, and means rearward of such partitions t0 regulably direct the air streams toward the central as stream.

2. In a metallurgical furnace, a centrally located gas inlet and air passages located laterally thereof, in each end of the furnace, said passages each containing a longitudinal partition, and combined damper and regulable deflector means rearward of such partitions to direct the air streams toward the central gas stream.

3. I11 a metallurgical furnace, a centrally located gas inlet, and air )assages located laterally thereof, in each end of the furnace, said passages each containing a longitudinal partition, and combined damper and regulable deflector means rearward of such partitions to direct the air streams toward the central gas stream and being fully withdrawable from the passages.

a. In a furnace of the character described, the combination of a hearth, a gas port at the end thereof, an air duct beside said port discharging into the upper portion of the furnace, a. longitudinally ext-ending vertical partition in the front portion of said duct, and a deflector to the rear of said partition adapted in one position to divert the air through the sub-passage between said partition and said gas port and in another position to leave said duct entirely clear.

5. In a furnace of the character described, he combination of'a hearth, gas inlet means at the end thereof, an air duct beside said gas inlet means discharging into the upper portion of the furnace, a longitudinally extcnding partition in the front portion of said duct, the sub-passage between said partition and said gas inlet means being of smaller cross-section at its front than at its rear end, and a deflector to the rear of said partition adapted in one position to divert the air through the sub-passage between said partition and said gas inlet means and in another position to leave said duct entirely clear.

6. In a furnace of the character described, the combination of a hearth, a gas port at the end thereof, two air ducts, one on each side of said port, discharging into the upper portion of the furnace, a longitudinally extending vertical partition in the front portion of each of said ducts, and a deflector to the rear of each such partition adapted in one position to divert the air through the sub-passage between said partition and said gas port and in another position to leave said duct entirely clear.

7 In a furnace of the character described, the combination of a hearth, gas inlet means at the end thereof, two air ducts, one on each side of said gas inlet means, discharging into the upper portion of the furnace, a longitudinally extending vertical partition in the front portion of each of said ducts, the subpassage between said partition and said gas inlet means being of smaller cross-section at its front than at its rear end, and a deflector to the rear of said partition adapted in one position to divert the air through the sub-passage between said partition and said gas inlet means and in another position to leave said duct entirely clear.

8. In an open hearth furnace, combined port means for incoming air and fuel, an uptake leading to'such combined port means, and additional fuel supply ducts extending from without the furnace to discharge at the port means.

9. In an open hearth furnace, combined port means for incoming air and fuel, an uptake leading to such combined port means, fuel supply ducts leading from the outside to discharge at the port means, and means for regulating the angle of discharge of air at the port means.

10. In a furnace of the character described, the combination of a. heart-h, gas inlet means at the end thereof, an air duct beside said gas inlet means discharging into the upper portion of the furnace, a longitudinally extending vertical partition in the front portion of said duct, said partition having a wall converging inwardly, and a deflector at the rear of said partition.

11. In a furnace of the character described, the combination of a hearth, gas inlet means at the end thereof, an air duct beside said gas inlet means discharging in the upper portion llQ i is

of; the: furnace v a; longitudinally extending vertical partition inthe front portion of saidv duct, said partition having a Wall converging inwa-rdly, at deflector to the rear of said partition, and means for regulating the, angularity of said defleotor.

Signed by 1119,.511152181} day of June, 1921.

STANLEY H. MGKEE.

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