US1911495A - Open hearth furnace - Google Patents

Description

May 30, 1933. w. c. FRNK Er AL OPEN HEARTH FURNACE Y Filed April 8. 1931 5 Sheets-Sheet 1 May 30, 1933. w. c. FRANK Er Al.

OPEN HEARTH FURNACE Filed April 8, 1931 5 Sheets-Sheet 2 May 30, 1933. w. c. FRANK ET AL 1,911,495

OPEN HEARTH FURNACE .Filed April 8. 1931 5 Sheets-Sheet 3 Jwuenlow IVe/Z252 Z. Howell.

Patented May 3Q, 1933 UNITED STATES PATENT oFI-lca WILLIAM C. FRANK AND FRANK E. HOWELLS, F JHNSTOWN, PENNSYLVANIA, ASSIGNOBS T0 BETHLEHEM STEEL COMPANY, A CORPORATION 0F PENNSYLVANIA OPEN HEABTH FURNACE Application. mea Aprile, 1981. serial No. 528,584.

Our invention relates to improvements in open hearth furnaces of the regenerative type having regenerators which are adapted to conserve the heat and add to the temperature .'-3 of the furnaces for the treatment of iron and steel or the like', wherein air and gasv or other gaseous or 'vaporizable combustibles are received at one end and directed over the hearth or bath and then the oil' gases disl) charged from the other end of the furnace.

Regenerators at the opposite ends of the furnace are adapted to heat the incoming air and gases before they enter the furnace, While the off gases from the furnace heat the regenerators at the opposite end of the furnace, the flow being reversed as the incoming air cools the regenerators to a certain temperature at that end of thel furnace.

In the usual open hearth furnace practice in which producer gas or the like is used it has been the usual custom to have a pair of regenerators at each end of the furnace, one for heating theI gas, and the other for heating the air.

With our invention however the air alone is heated.

One of the objects of our invention relates to forming the 4regenerators of checker brick Work with a plurality of passes and sections, in such a way as to greatly increase the length of the heating ducts whereby a better and more economical manner of heating the air is obtained and a higher temperature for the air passing therethrough secured.

Another object of your invention relates to forming 'the first pass of the regenerator which is first subjected to the ott gases of larger sized brick -and Hue ducts or passages and .of irebrick capableof a higher resist- 40 ance as to the melting point than those of which the remainingpasses of the regenerator are'formed, such bricks may be composed of chromite, magnesia, alumina, bauxite or silica or the like, although the first 5 three kinds of brick are the most desirable to the manner. of inclosing and insulating on account of their higher temperature resistance as to the melting point.

Another object of our invention relates to the construction of the nozzles and caps for the cleanout holes in the front and back end walls4 of the regenerators.

Another object of our invention relates to forming a cooling passage or channel through the middle buttress between the uptake which provides a means Vfor Ventilating the space between the furnace bottom and the slag pocket roof, and also to act as a chill for the middle buttress which supports or stifens the furnace end wall.

Another object of our inventionrelates to formin the slag pockets of ample capacity and so esigned that the ofi:` ases have a c'inparatively lon passage be ore entering the ducts of the rst pass of the regenerator. This 'long passage Ain conjunction with the s'low velocity, because of the large volume slag pocket, helps to separate much of the suspended slag particles before entrance to the checkers.

Another object of our invention relates to the manner of forming an air-cooled bridge Wall beneath one end of the slag-pocket and under one end of the first pass of the regenerator whichis open at each end to allow a cooling medium to circulate therein and the heated air to easily escape from each end of the bridge Wall.

Another object of our invention relates the walls of the regenerators. A

Other. objects will appear hereinafter. Having thus given ageneral description of our invention we will now, in order to make the matter more clear, refer to the anneXed live sheets of drawings in which like characters of reference indicate like parts.

Figure 1 is a sectional plan taken substantially on the line 1-1 of Fig. 3;

Fig. 2 is a transverse section taken on the line 2 2 of Fig. 1;

Fi 3 is a longitudinal section through the mace taken on the line 3-3 of Fig. 1; Fig. 4 is/a vertical `section drawn on a larger scale ,taken at the front end of one ing the back'wall and adjacentportions of one of the regenerators and a portion of the slag pocket taken on the same l1ne as Fi 2' Fig.7 .is a detail section drawn on an enlarged scale of one of the nozzle closures for one of the cleanout. holes in the walls of the regenerator in alignment with the flue passages; and,

Fig. 8 is a detail section of one of the manhole constructions taken on the line 8-8 of Fig. 1. v

It will be understood that .the construction of both ends of the furnace and the re generators therefor are similar and a description of one end will apply to both.

Referring now to the characters 'of ref-v erence on the drawings the furnace generally is indicated as 1, the hearth as 2, the roof as 3 and the end walls as 4. Beneath each end of the furnace proper is aslag-pocket, communicating with the ends of the furnace by means of a pair of uptakes 6 and ort openings 7 The uptakes 4are separate by means of a buttress 8 having a cooling passageway or tunnel formed therein at an '1ntermediate point as at 9, between the end of the furnace and the furnace bottom adapted to provide means for ventilating the space between the furnace bottom and the slagpocket roof and also to act as a chill for the middle buttress.

Mounted u onor formed as a part thereof and exten ing above the buttress into the air port openings'7 is an arched portion 10 formed w1th a burner .opening 11 for receiv ing a burner 12 by means of which the furnace is fired, which is supplied with suitable fuelsuch as gas, oil, tar or the like.

-The slag-pockets 5 at each end of the furnace are of ample capacit and are so designed that the off gases om the furnace have a' comparatively long passage before entering the first checker brick pass of the regenerators. This long passage in conjunction with the slow velocity, because of the large volume or area of thel slag-pockets, helps to separate much of the suspended slag particles before entrance to the first pass of the regenerators.

The arrangement and construction of each of our regenerators is what is known as a single surface type, in which the heat of the outgoing or off gases is applied to and` -absorbed by the-Iche'ckers, walls, etc. and

given back to the incoming cold air'from the same surfaces of the checkers, walls, etc. which received the heat.

These regenerators as above'described dif# fer from heat recuperators, which are of the double surface type, said recuperatorsdepending upon the 'heatutransferred or conducted throu h the materials of which they are compose the heat being applied'to'one P side of the materials and transmitted through them to .the other side thereby the gases or air is heated.

The regenerators in our construction are each formed with three passes 13, 14 and 15 in such a manner as to greatly increase the length of the ducts over the single surface one pass regenerators now in use and thereby increasing the temperature of the air be ing heated. The upper pass-indicated as 13 has its back end extending beyond the lower two passes 14 and 15. yIt will also be noted that the frontend of the lower pass 15 extends beyond the passes 13 and 14 and in staggered relation with the top pass 13,

thereby formingl a chamber` at each end of the regenerator above the front portion of the pass 15 and below the rear portion of` the upper pass 13, as clearly indicated in Fig. 2 of the drawings.

Built directly under the back end of the first pass 13 and extending upwardly from thel front end of the bottom of the slag-pocket is a bridge wall 16 having an inclined surface 17 which .is adapted to deflect the flow of oif gases and further assist in separating the suspended slag particles and to prevent a ledge being formed and accumulations to build up and choke the entrance of the gases to the checkers 'of the first pass 13. The l bridge wall 16 is provided with a tubular air cooled passageway 19 which is open at each end to allow for the free circulation of cold air therein to protect the bridge wall and cool any slagdeposited thereon.4

As the upper pass 13 of the regenerator is subjected to intense heat by the off gases the bricks of which it is formed and the flue ducts therein are made of larger size than vthose of which the 'other two passes 14 and 15 are constructed, the fire brick being formed of material capable of a higher resistance as to the melting point than those of which the other two passes of the y regenerator are formed. y

The three passes of the regenerators are divided horizontally by means of bale ' walls 20 and 21. The upper pass 13 extends entirely across the top of the regenerator and is of larger capacity than the lower two which are both divided Vcentrally by means of walls 22 and 23.

Apertures 24 and 25 are formed in the front and rear walls 26 and 27 respectively in alignment with the ducts of the regenerators, to

allow for inspection and for the insertion of a. tool for cleaning out theducts from time to time as it becomes necessary. These apertures are closed by means of nozzles 28 welded, to the wall casing as at 29 and having caps 30 screwed on the outer ends for closing the same. This manner of formin individual cleanout holesfer the ducts of t e regenerators has the advantage over large doors heretofore used, as the doors allow too much heat and air leakage when open, as the working conditions of the men engaged in cleaning the regenerators when doors are used is very ser vere.

When it is desired to clean the ducts of the regenerators, a cap 30 is removed and that particular duct is cleaned by means of a steam or air lance or the like, the cap is then replaced. This continues until all of the ducts have been cleaned, the dirt accumulating in the chambers 31 and 32 can easily be removed through doorways 33 and 34 provided in the walls of the regenerator chamber.

To prevent air infiltration and cut down the heat radiation, we have encased each of the regenerator chambers and slag-pockets with a steel casing 35 and an insulation 36. This steel casing is welded together at the joints to be waterproof below the ground level. In this manner the sides of the steel casing are exposed to the air for cooling and are accessible for repairs, etc., and any warping of the steelwork due to high temperature is eliminated.

The front end of the lower pass 15 of each of the regenerators are each connected by means of a divided conduit 37 having cleanout man-holes formed therein as at 38. This divided conduit 37 extends to an Isley stack control 39 which controls the admission and ilow of cold air and the exhaust of the olf gases to and from the furnace. This Isley stack control which is of standard construction forms no part of the present invention will be readily understood by referring to Patent No. 1,762,299, issued to` G. H. Isley, J une 10, 1930.

- Having thus given a description ofpour invention we willnow describe the operation:

Referring to Figs. 1, 2 and 3 of the drawings; assuming that the incoming air and off gases are flowing through the furnace from left to right as indicated by the arrows, the burner at the left hand side of the furnace being turned on and that at ri ht hand side of the furnace cut off, cold air om the Isley control is forced through the divided conduit 37 at the left hand side of the furnace and enters the regenerator and flows in a zig-zag or sinuous manner from the lower pass15 of the regenerator, which has been previously heated by the off gases of combustion, into the intermediate pass 14 and then into the upper pass 13, during which period the air r becomes highly heated as it passes through the ductsl of the regenerator. The highly heated air then flows through the slag-pocket 5 and then to the uptakes 6 and port o ening 7 where it en ages the ame of the urner 12 at the left and end of the furnace and is deflected by the Venturi throat of the furnace work of the regenerator, from which point the olf gases are conveyed through conduit 37 to the Isley stack control 39 and exhausted.

After the furnace has been operated in the manner described for the proper or desired length of time to cool the regenerator at the left hand end of the furnace to a certain ternperature, the burner at the right hand end of the furnace will be opened and the burner at the opposite end of the furnace closed. The flow of air and ofi' gases will then be reversed by means of the Isley stack control whereupon a reversal of currents takes place and the air and gases will iow through the fur'- nace from right to left and ,in the direction opposite to the arrows on the drawings.

Although we have shown and described our invention in considerable detail, we do not wish to be limited to the exact and specific details shown and described, but may use such substitutions, modifications or equivalents thereof as are embraced within the scope of our invention, or as pointed out in the claims. Y

Having thus described our invention what we claim and desire to secure by Letters Patent 1s: a

1. In a regenerative furnace, a three pass regenerator of the single surface type connected t0 each end of the furnace arranged with their passes superimposed in vertical allgnment, one of the passes of the regenerator being of greater capacity and formed of a different kind of refractory material extending the full length of the pass and having a greater heat resistance than the other two passes, baille walls extending longitudinally between each of the passes of the regenerators,

.a connection between the upper and central pass at one end of the regenerators, a connection between the lower and central pass at the opposite end of the regenerators and ducts extending longitudinally through each pass adapted to receive and provide a sinuous path for Vthe iow of air to the furnace and to receive the flow of oil gases of combustion when the flow of air to the furnace is reversed.

2. In a regenerative furnace, a three pass lregenerator of the single surface type conpasses of the regenerators, ducts extending longitudinally through each of the passes of the regenerators adapted to receive and provide a sinuous path for the flow of air to the furnace and to receive the liow of olf gases of combustion when the flow of air to the furnace is reversed, the upper pass of the regenerators being of greater capacity and formed of a different kind of refractory material throughout the length of the pass and having a greater heat resistance than the lower two passes, said ducts in the upper pass lbeing of larger size than the ducts in the lower two passes. j

3. In a regenerative furnace, a three-pass regenerator of the single surface type connected to each end of the furnace arranged with their asses superimposed in vertical alignment, aie walls extending longitudinally between adjacent passes, a connection between the ends of two of the passes at one end of each of the regenerators, a connection between one of the said two passes and an adjacent pass at the opposite end of each of the regenerators, the upper pass of the regenerator having ducts extending longitudi,

nally across the entire width of regenerator, a central wall dividing each of the lower passes and ducts of smaller size than those through the upper pass extending longitu. dinally through the. lower passes.

` 4. In a regenerative furnace, a reversing regenerator connected to each end of the furnace, a plurality of passes arranged in vertical alignment for each regenerator, a plurality of ducts in each of the passes of the regenerator, a wall surrounding the regenerators, a metal casing surrounding the regenerator walls an aperture in the wall and metal casling of the regenerators in alignment with each of the ducts, a nozzle for each aperture having -its inner end welded to the casing, and a cap secured to the outer end of each nozzle for closing the apertures.

5. In a regenerative furnace, a reversing regenerator of `the single surface type connected to each end of the furnace, a plurality of passes arranged with their passes superimposed in vertical alignment for each regenerator, ducts extending longitudinally in each of the passes of the regenerators, a connection between a pair of adjacent passes at each end of the regenerators, a wall surrounding the regenerators, insulation surrounding the walls of the regenerators, a metal casing surrounding the insulation, an aperture in the walls of .the'regenerators extending through ent nace, a chamber-connecting th upper and central pass at one end of the regenerators, a chamber connecting the lower and central -pass atythe other end of the regenerators, a

slag-pocket between each regenerator and the furnace, a bridge wall in each slag-pocket beneath the up er pass of the regenerator, and a tubular coo ing passageway formed in the bridge wall.

7 In a regenerative furnace, a single surface three-pass regenerator connected to each end of the furnace, a plurality of longitudinal superimposed passes formed in the regenerator, the upper pass of each of the regenerators being of greater length and capacity than the other passes of the regenerator, a slag-pocket between each regenerator and the furnace, a bridgefwall in each slagpocket having an inclined face extending upwardly to the lower edges of the upper pass of the regenerator, and a tubular cooling passageway formed in the bridge wall.

8. In a regenerative furnace, a single surface three-pass reversing regenerator at each end of the furnace, sald regenerators each formed with the plurality of passes superimposed in vertical alignment, the upper pass of each regenerator bein longer and lof ater capacity than the ot er passes of t e re' generator, a connection between a pair of the passes at each end of the regenerators, a slagpocket between each regenerator and the furnace, a bridge wall in each slag-pocket having an inclined side face extending upwardly to the upper pass of eachregenerator, and a tubular cooling passageway formed in each bridge wall.

9. In a regenerative furnace provided with a hearth, a reversing regenerator connected to each end of the furnace, a slag-pocket between each `regenerator and the furnace hearth, a pair of uptakes between each slagpocket and the ends of the furnace hearth, a buttress between each pair of uptakes, and a tunnel formed in each buttress above the slag pocket betweenthe end of the furnace and the bot-tom of the furnace hearth.

10. In a regenerator furnace provided with" a hearth, `a reversing single surface regenerator, connected to each end of the furnace, a

'slag-pocket between each regenerator and the -ends of the furnace hearth, a bridge wall formed in each slag-pocket, a tubular cooling passageway formed in each bridge wall, a pair of uptakes between each slag-pocket and the ends of the furnace hearth, a buttress between each pair of uptakes, and an air cooling` longitudinal -ducts formed in each of the i tunnel formed in each buttress between the ends of the furnace and bottom of the furnace hearth.

11. In aA regenerative furnace provlded with a hearth, an air reversing regenerator connected to each end of the furnace, a plurality of passes superimposed in vertlcal alignment for eachfregenerator, baile walls between adjacent passes of the regenerators, a chamber connecting an upper and an intermediate pass at one end of each of the regenerators, a chamber for connecting a lower and said intermediate pass at the opposite end of each of the regenerators, longitudinal ducts formed in the passes of the regenerators, a wall surrounding each regenerator, apertures in the front and rear walls of the regenerators in alignment with the ducts of the regenerators, a nozzle having a cap screwed thereon for closing each aperture, a slag pocket between each regenerator and the furnace, a pair of uptakes between each of the slag-pockets and the end of the furnace, a buttress between each pair vof uptakes, and an air cooling tunnel formed in each buttress between the ends of the fur.-`

nace and the bottom of the furnace hearth. 12. In a regenerative furnace provided with a hearth, an air reversing regenerator connected to each end of the furnace, said regenerators each formed with three passes superimposed in vertical alignment, longitudinal baie walls between adjacent passes of the regenerators, a chamber at one end of each of the regenerators for connectin the upper and central passes together, a c amber at the opposite end of each of the regenerators for connecting the central and lower passes together, longitudinal ducts formed in each of the passes of the regenerators, an insulated wall with a casing surrounding each of the regenerators, apertures in the front and rear walls of the regenerators in alignment with the ducts of the regenerators, a nozzle welded to the casing having a cap screwed thereon for closing each aperture, a slagpocket between each regenerato'r and the furnace, a pair of uptakes between each of the slag-pockets and the end of the furnace, a buttress between each pair of uptakes, and an air cooling tunnel formed in each buttress between the ends of the furnace and the bottom of the furnace hearth.

13. In a regenerative furnace provided with a hearth, an air reversing regenerator connected to each end of the furnace, said regenerators each formed with three passes superimposed in vertical alignment, longitudinal baille walls between adjacent passes of the regenerators, a chamber for connecting two of the passes at one end of each of the regenerators, a chamber for connecting one of the said two passes with another pass at the opposite end of each of the regenerators,

bridge wall in each s1 passes of the regenerators, an insulated wall with a casing surroundin each of the regenerators, apertures in t e front and rear walls of the regenerators in alignment with the ducts of the regenerators, a nozzle welded to the casing having a cap screwed thereon for closing each aperture, a slagocket between eacl -pocketl having an inclined side face extendin upwardly to the base of the first pass of t e regenerator, a tubular cooling passageway formed in `each bridge wall, a pair of uptakes between each of the slag-pockets and the end of the furnace, a buttress between each pair of uptakes, and an air cooling tunnel formed in each `buttress between the ends of the furxiace and the bottom of the furnace hearth.

14. In a regenerative furnace, a reversing regenerator connected to each end of the furnace, three passes superimposed in vertical alignment formed in eachre enerator, a chamber at one end of each of 5i tors for connecting the upper and central passes together, a chamber at the opposite end of each of the regenerators for connecting the central and lower passes together, a bale wall between the top and adjacent passes extendin over and formin the top of one of the c ambers at one en of each of the regenerators, a baille wall between the lower and adjacent passes extending under and forming the bottom of the other chamber at the opposite end of each of the regenerators, and ducts extending lon 'tudinally throu h each pass adapted to orm a sinuous pat to receive the flow of air to the furnace and the off gases of combustion from the furnace.

15. In a regenerative furnace, a single surface reversing regenerator connected to each end of the furnace, three passes superimposed in vertical alignment formed in each re enerator, a chamber for connecting two ofg the passes at one end of each of the regenerators, a chamber for connecting one of the said two passes with an additional pass at the opposite end of each of the regenerators, ducts extend'- ing longitudinally through each pass adapted to form a sinuous path to receive the flow of air to the furnace and the oil' gases of combustion from the furnace, a slag-pocket of large area between each of the regenerators and the. furnace, a pair of uptakes between e regenera-` regenerator and the urnace, a

each of the slag-pockets and the end of the furnace, and an air cooled buttress between the uptakes and a burner mounted at the top of each buttress for heating the furnace.

. 16. A regenerative furnace provided with a hearth, a three pass single surface reversing regenerator connected to each end of the furnace having horizontal passes of substantially the same cross-sectional area superimposed in vertical alignment, the upper pass of each of the re enerators extending beyond pass of each regenerator, a direct connectlon etween the slag-pocket and the extending back end of theupper pass of each of said regenerators, a chamber at the front end. of each of the said regenerators for connecting the upper and intermediate passes together, and a chamber below each of the extending ends of the upper pass of the regenerators for connecting the ends of the lower and the said intermediate passes together.

17. In a regenerative furnace provided with a hearth, a three pass single surface reversing regenerator connected to each end of the furnace having horizontal 1passes superimposed in vertical alignment, t e upper pass of each of the regenerators extending be ond the back end of the other two passes an the lower pass of each regenerator extending beyond the forward end of the upper two passes of each of the regenerators, a slag-pocket between each regenerator and the end of the furnace hearth, a bridge wall in each slagpocket having an inclined face extending upwardly to the lower edge of the upper pass of each regenerator, a connection between the slag-pocket and the back endv of the u per pass of each regenerator, a chamber a ove the forward extending end of the lower pass for connecting the upper and said intermediate passes of each ofthe regenerators tov gether, and a chamber below the extending back end of the upper pass for connecting the lower and said intermediate passes of each of the regenerators to ether.

18. In a regenerative urnace provided with a hearth, a three-pass reversing regenerator connected to each end of the furnace having horizontal passes superimposed in vertical alignment, the upper pass of each of the regenerators extending beyond the back end of the other two passes and the lowe pass of each regenerator extending beyond the forward end of each of the upper two passes of the regenerators, a baille wall extending longitudinally between the upper and intermediate passes extending substantially the full length of the upper ass, a baille wall between the lower and sai intermediate passes extending longitudinally the full length of the lower pass in each regen erator, a bridgewall in each slag-pocket having an inclined face extending upwardly to 4the lower edge of the upper pass of each regenerator, a connection between the. slagpocket and the back end of the upper pass of each of the regenerators, a chamber above the forward extending end of the lower pass for connecting the upper and said intermediate passes of each of the regenerators tother, and -a chamber below the extending ack end of the u per pass for connecting the lower and sais intermediate passes of each of the regenerators together.

19. In a regenerative furnace, a three pass reversing regenerator connected to each end of the furnace having horizontal passes superimposed in vertical alignment, the upper Esse' of each of the regenerators extending yond the back end of the other two passes and the lower pass extending beyond the forward end of each of the upper and said intermediate passes of the regenerators, a wall surrounding each regenerator, a metal casing surrounding each of the regenerator walls, a chamber above the forward extending end of the lower pass between the ends of the upper and intermediate passes and the front end wall for connecting the ends of the passes together, a chamber below the extending back end of the upper passes between the ends of the lower and said intermediate passes and the back wall of the regenerators for connecting the lower and said intermediate passes together, an aperture in the front end wall of each of the regenerators in alignment with each of the ducts of the upper and intermediate passes of the regenerators, an aperture in the back wall in alignment with each of the ducts in the lower ass, a nozzle for each aperture having its inner end welded to the casing, and a cap secured to the outer end of each nozzle for closing the apertures. l

20. In a regenerative furnace provided with a hearth, a three pass reversing regenerator connected to each end of the furnace provided with ducts forming horizontal passes superimposed in vertical alignment,

the upper pass of each of the regenerators- .per and said intermediate passes of the regenerators, a slag-pocket between each regenerator and the end of the furnace hearth, a bridge wall in each slag-pocket having an inclined face extending upwardly to the lower edge of the upper pass of each re enerator, a connection between the slag-poc et and the back end of the upper pass of each of the regenerators, a wall surrounding each regenerator, a metal casing surrounding the regenerator walls, a chamber above the forward extending endA of the lower' pass between the ends of the upper and intermediate passes and the front end wall for connecting the ends of the passes together, a chamber below the extending back end of the upper passes between the ends of the lower and said intermediate passes and the back wall of the regenerators for connecting the lower and said intermediate passes together, an aperture in the front end wall of each of the regenerators in alignment with each of the ducts of the regenerators of the up r and intermediate passes, an aperture in t e back wall in alignmentilwith each of the ducts in the lower pass, a nozzle for each aperture having its inner end welded to the casin and a cap secured to the outer end of eac nozzle for closing the apertures.

In testimony whereof we hereunto ax our signatures.

WILLIAM C. FRANK. FRANK E. HOWELLS.

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