US1798871A - Open-hearth furnace - Google Patents

Description

March 31, 1931. N. F. EGLER OPEN HEARTH FURNACE 3 sh'ets-sheet 1 Filed Sept. 5, 1929 INVENTOR amt March 31, 1931. N EGLER OPEN HEARTH FURNACE Filed Sept. 5, 1929 5 Sheets-Sheet 2 INVENTOR N. F. EGLER OPEN HEARTH FURNACE March 31, 1931.

Filed Sept, -5, 1929 5 Sheets-Sheet 3 Patented Mar. 31, 1931 1,798,871

UNITED STATES PATENT OFFICE NIKLAS F. EGLER, F MONESSEN, PENNSYLVANI OPEN-HEA13LTH FURNACE Application filed September 5, 1929. Serial No. 390,471.

My invention relates to open-hearth furtake 4, and thence through port 2 to the furnaces, and consists in structural provisions nace chamber. A second slag pocket 7 is which may be added to a furnace of standard provided, which communicates with the air type with little or no interruption of operregenerator 9, and two vertically arranged 5 ation; and which, being added, increase air uptakes 5 are provided, communicating the serviceability of the furnace, and render with slag pocket 7 below and with the all the furnace adaptable to reconstruction, so port 3 above. In operation atmospheric air, far as concerns its more destructible accesdrawn through regenerator 9, slag pocket 7, sorv parts, and adaptable to reconstruction and uptakes 5, enters the furnace chamber 10 with little or no interruption of operation, through port 3. These are the two lines of so so that the furnace may in the main be conflow of gas and of air at the intake end of tinned indefinitely in substantially uninterthe furnace. At the outgoing end the prodrupted operation. Incidentally, the invennets of combustion stream through both tion involves the adaptation of a furnace inports, down all three uptakes, through both tended for use with gas as fuel to alternative slag pockets, and both regenerators, and as use with a fixed fuel, so called, such as tar thence off to the stack. It is deemed unor oil or natural gas. necessary to show the means by which peri- In the accompanying drawings Fig. I is a odically the furnace is reversed, the end view in vertical and longitudinal section of which had been the outgoing end becomes in an open-hearth steel furnace of standard turn the intake end and the opposite end the 70 type, otherwise of familiar structure, but outgoing end. These reversing means are having added to it those features in which well known. Such, in general terms, is the my invention is found. The plane of secopen-hearth furnace of standard type, to tion is at the left-hand end medial, through which, in the practice of m inv n -i 11.

the gas uptake; at the right-hand end the structural features are added. re plane of section is that indicated in Fig. II These added structural features are, first by the line I-I, through an air uptake. fuel burners, introducedthrough the end Fig. II is a fragmentary view in approXiwalls into the ports 2 at the two ends of mately horizontal section, on the plane indithe furnace. These burners,- conventionally cated by the broken line IIII, Fig. I. shown in Fig. I of the drawings, are arso Figs. III and IV are views in vertical and ranged to deliver jets of fuel-oil, for intransverse section, on the planes severally stance, or tar-longitudinally through the indicated by the lines III-III and IV-IV, fuel port and into the furnace chamber.

Fig. I. They preferably are removable in such place- The open-hearth furnace here illustrated, ment. in that 1t is of standard construction, in- The second added structural feature is a eludes the following parts: A hearth l with closure for each of the two conduits through duplicate ports and accessory parts at the which in the standard operation outlined two ends. The gas port 2 at each end is above gas flows alternatively from one or medially arranged; and the air port 3 overthe other of the slag pockets 6 to the gas arches the gas port. At lower level are port. This closure advantageously takes the bu lt regenerators-a gas regenerator 8 and form of a valve 12 arranged at the upper an air regenerator 9. A slag pocket 6 is end of thegas uptake. This valve may, conprov1ded, which communicates with the gas veniently, be formed of refractory material,

45 regenerator 8, and a vertically arranged gas suitably reinforced and held together by a uptake 4 is provided, communicating with metal frame, and it is preferably adjustable, slag pocket 6 below and with gas port 2 to close the uptake entirely, or to close it above. In operation gas flows fromasuitable to any clesirecl degree, or, alternatively, to source, a gas generator, for instance. leave it entirely open and unobstructed.

59 through regenerator 8, slag pocket 6, Th thi d a d. last feature, added to th lot standard structure in embodiment of my invention, is a conduit through which communication is established at each end of the furnace between the air port and the slag pocket 6. This conduit is advantageously constructed as shown in Figs. I and II. It there is shown to consist in vertically arranged passageways 13, duplicated on the two sides of the furnace, just as the air uptakes 5 are duplicated, built externally upon the standard structure, extending immediately adjacent the two air uptakes 5 and separated, severally, from the air uptakes merely by the furnace wall. Openings are made through the masonry of the standard structure through which at the upper end there is free communication between the air uptake 5 and'the passageway 13, and at the lower end free communication between the slag pocket 6- and the passageway 13. I

By the structural adaptation described a standard furnace built for use of producer gas as fuel and having both gas and air rege'nerators may be transformed at slight expense, and with practically no loss in working'time, to a very excellent working furnace using tar, oil. natural gas, or any similar fixed fuel, whereinit is unnecessary or inadvisable to regenerate the fuel. I have found that a steel furnace so reconstructed consumes a markedly less amount of fuel or B. t. u.s per ton of steel produced than has been ordinarily considered possible heretofore.

In addition, there are in many steel plants times when it becomes necessary, dueto varying economic conditions, to change on short notice from producer gas to tar or oil or other fixed fuel, and vice versa To reconstruct the furnace along lines of the prior art has required not only an expenditure of relatively large sums of money, but additionally the taking of the furnace out of production for several weeks or months. Obviously, when tonnage is demanded, such delay can scarcely be countenanced. -Moreover, with the necessity for such delays, there is danger that the economic conditions may during the time of the reconstructionhave changed to such extent that the purpose in view in making the reconstruction may bedefeated.

In addition, another feature which presents itself to the advantage ofmy furnace results from the fact that all furnaces, after beingrin service for a number of heats, have the checker work in their air regenerators clogged up, thus limiting notonly the draft but also the regenerative capacity of the fur mice. In conseduenca'the time for making thehezit becomes longer and longer, until finally the. furnace becomes so slow thatit must be shut down and rebuilt, even though it would have endured for many more heats, so far. as. concerns the integrity of the masonry andof other parts. WVithmyinvention,

a furnace which has begun to run slow may, at very slight expense and with no appreciable delay, be brought right back to proper speed. The effect is that the furnace may be operated for many more heats continuously.

In the operation of the standard furnace as explained above, and leaving out of consideration the added structural features of my invention, it is obvious, from the relatively small size of the gas port 2, that at the outgoing end of the furnace a relatively small fraction of the gases will pass through the gas port 2, uptake 4, slag pocket 6, and regenerate-r 8; and that in consequence the checkerwork in the gas regenerators will not be heated to nearly as high a temperature as will the air regenerators. Furthermore, for the same reason, the particles of dust, ash, and slag will pass largely into the air regenerators; so that the air regenerato-rs will become clogged up and ineffective for regener ating the incoming air, while the gas regenerators remain still clean and potentially capable of doing a great deal of effective work.

And it is additionally obvious that as the air regenerators become fouled the draft through the gas regenerators will be increased and a larger fraction of the outgoing body of gas will pass through the gas regenerators.

In the operation .of the furnace when modified by the structural additions described above, the valve 12 on the intake end of the furnace may be closed, and fixed fuel may be admittedthrough pipe or burner 1 1 and port 2 to the furnace chamber. No regenerated air is mixed with the fuel because uptake 4 V has been closed off by valve 12. The fuel as it enters the furnace chamber mingles with regenerated air which enters through air port 3. This air has entered the furnace both from the air regenerator 9, slag pocket '7, uptakes 5, and also from the gas regenerator 8 and slag pocket 6, coming from the latter into air uptakes 5 by means of the auxiliary communicating passages 18. After passing over the charge the products of combustion leave the furnace principally through port 3, because the fuel port 2 is relatively small, and, besides, position is partly shut, thus throttling the flow in uptake 4. On this outgoing end the.

products of combustion, leaving port 3 through air uptakes 5, divide; part going directly into slag pocket 7, and through regenerator 9 to the stack, and the remainder going through auxiliary communicating passages .1'3, slag pocket 6, regenerator 8, and thence to the stack. If there is not enough of the products of combustion passing into these auxiliarypassages 13 to heat the checkerwork in regenerator 8 to as high a temperature as in chamber9, the. valve 12 in uptake 4 is opened farther and an additional-quantity of these gases, then passesthrough port the valve 12 in its usual 2 u )take t and slax ocket 6 to re enerator m a a z: 8. lhe valve 12 may thus be used as a regulator, to keep the checkerwerk in the two regenerators at substantially equal temper tained ans, as a direct consequence, fuel consumption i B. t. u.s per ton of steel is lowered. Preferably the passages 13 are made so large that when in the course of operation they first come into play the valve 12 on the outgoing end may be left entirely shut and still allow enough of the products of combustion to piss into slag pocket 6 and regenerator 8. Later on, as the draft becomes lessened, valve 12 may be opened more and more to effect compensation. So long as the valve 12 remains closed, the burner 1a is not QI- posed to outgoing gases and may be left in place; when, however, valve 12 is opened, the burner 14 should be withdrawn.

In the furnace of the prior art, designed for fixed fuel only, a single regenerative chamber at each end of the furnace is used. This is made large, to allow for the fouling of the regenerator as operation continues and still to obtain suliicient draft for the carrying away of the products of combustion. When the furnace is new, therefore, the passageway through the checkerwork in the re generator is too large, the heat-exchanging areas too great, the bricks or tiles in the checkerwork are not brought up to asufiiciently high temperature, and, in consequence, when the furnace is reversed, the air which flows to the furnace is not heated sufficiently, the flame temperature in the furnace is low, and there is Waste of fuel. Moreover, after such a furnace has been in service long enough to clog up the passages somewhat, and to reduce the heat-exchanging area, still there is no gain, because the bricks or tiles which constitute the oheckerwork are then coated with less conducting material, and this prevents the outgoing products of combastion from giving up their heat to the oheckerwork. When the furnace is reversed, the air still is insufficiently heated and the JaStE of fuel continues.

out any such interruption of operation as toinvolve a putting of the furnace out of service. Alternatively, the masonry which on closes the pasageways 13 may have been built before the operation began, and the valves 12 may have been provided in advance, and the burners 14 may have been made ready, and in suchcase all that is needed to change the furnace over touse with fixed fuel, is to knock out masonry and establish communication for E the passageway 13 with the uptake 5 at its upper end and with the slag pocket 6 at its lower end, and to introduce the burner into the port 2, and, with suitable placement of the movableparts, to introduce the new fuelQ i;

Qperation will continue without substantial interruption and the relatively clean regencraters 8 will then serve to heat the entering air. When then, in continued operation, the I furnace begins to runslow, the air regenera tor may by the bricking up or closing off of the uptakes 5 be segregated, and the so segre gated regenerator may be cleaned or replaced,

and this may be done with practically no loss in time, for the furnace will continue in opg5 oration, the air entering through regenerator 8, slag pocket 6 and auxiliary passages 13; If, after still further continuance of operation it be desired, the reg-enerator 8 may bythe removing or the shutting off of the auxiliarybo passages 13 be segregated, the checkerwork in regenerator 8 may then" be cleaned, replaced,

' or repaired; and, meanwhile, the furnace will continue in operation, taking air through retherefore, that by this means the furnace may be continued indefinitely in operation, so far as concerns the slag pockets and regenerators, and at all times the air for combustion as it enters the furnace may be maintained at the generator 9 and slag pocket 7. It is evident, as

like, this may be done with very little eifort fi 5 and delay, by opening or removing valves 12 and closing or removing the auxiliary communicating passages 18.

I claim as my invention:

1. In an open-hearth furnace structure of standard type including a fuel port, an air port, a fuel uptake communicating with the fuel port, an air uptake communicating with the air port, and two regenerator chambers,

with each of which one of said uptakes is in 1 .15

communication, supplementary equipment by which the furnace may be adapted for the use of fixed fuel, suchas tar and oil, such supplementary equipment including a burner in the fuel port, a valve in the fuel uptake, and a 12 by-pass between the regenerator with which as aforesaid the fuel uptake is in communication and the air port.

2. In an open-hearth furnace structure of standard type including a fuel port, an air port, a vertically extending fuel uptake communicating at its upper end with the fuel port, a vertically extending air uptake communicating at its upper end with the air port,

and two regenerator chambers arranged at lower level than the-parts vnamed witheach of whichaoneof said uptakesis-at. its lower end ini-cemlnun-ication, supplementary equipment by which the furnace may be adapted forthe 5 userof'fixed fuel-,such as tar-and oil, such supplementary equipment including a burner in :thefuelport, a valve in the fuel uptake, and :wpassageway extending vertically from the "regenerator with which the fuel uptake is in l commimicati'on and separated from the air nptake by aported wall.

-3. In :an open-hearth furnace structure of standardw'typ-e includinga fuel port, an air p0rt, a f-uel uptake communicating with the fuel-port, an-air uptakecommunicating with uthecairport,'and two regenerator chambers, with each of which oneof-said uptakes is in communication, supplementaryequipment by which the furnace may beadapted for the use .,20 of fixed f-uel,-suchsupplementaryequipment includingaiburner for fixed fuel'a'rranged to project its :fiame through: the fuel port to: the furnace chamber, avalve in' -t-he fuel uptake adapted-when closedto cut off flow through e-zfi-the fuel uptake, and .a bypass through which communication: isestablished between the regeneratorwith whichas aforesaid the fuel uptake-is in communication and the air port.

'30 .In-testim0ny whereof 1 have hereunto set rm-y hand.

NIKLAS EGLER.

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