US2351661A - Regenerative soaking pit furnace - Google Patents

Description

June 20, 1944. J, w, CARTER ETAL 2,351,661

REGENERATIVE soAKING PIT FURNAGE Fild Aug. 27, 1941, 3 Sheets-Sheet l June 20, 1944. J. w. CARTER ET AL REGENERATIVE SOAKING` PIT FURNCE v Filed Aug. 27, 1941 s sheets-sheet 2 lilll! [mations:

June 20, 1944. J, W- CARTER ET AL `2,351,661

I QEGENERATIVE SYOAKING PIT FURNACE Filed Aug. 27, 1941 l 3 sheets-sheet 3 Patented June 20, 1944 AUNITED STATE-S PATENT OFFICE REGENERATIVE SOAKING PIT FURNACE J ohn W. Carter and Andrew Reed Rowe, McKeesport, Pa., assignors to National Tube Company, a corporation of New -Jersey ApplicationAugust 27, 1941, Serial No. 408,524

4 lcl. 263-15) 4Claims.

This invention relates to regenerative soaking pit furnaces employed for heating steel ingots and the like.

In present furnaces of the character stated, considerable difficulty is encountered due to the escape of molten slag from the pit. 'I'his fugitive slag or liquor is formed upon the surface of the ingots and drips into the bottom" of thepit. Although suitable drains are provided to remove this slag at certain intervals, the slag accumulates in the pit.

Such a condition is a continual hazard to the furnace structure, due to the aillnity of the slag and the brick or refractory of the furnace which causes pitting of the latter, and upon repeatedl heating and cooling of the furnace structure in its regenerative operation, cracks are formed in the refractory through which the slag escapes in a downward and outward direction. Since the usual design of such furnaces locates the checker work entirely orat least partly below the level of the hearth and bottom` of the pit, the fugitive slag eventually enters and clogs the checkers'.

In such a case, the furnace must be shut down and the checkers and refractory rebuilt, causing prolonged delays and considerable expense.V

Such furnaces are a potential source of trouble and expense at all times because the time of failure is unpredictable, it being impossible to predetermine the life of the furnace brickwork even by change of refractory material, thickness, etc.

It is a prime object of this invention to so construct and arrange the furnace parts as to insure against the hazard of fugitive slag and to prevent the same from entering and clogging the regenerator chambers.

Our invention contemplates the construction and disposition of the regenerator chambers and checkerbrick at 'a sufficient level above that of the bottom of the soaking pit so that escaping slag cannot flow into said chambers but will escape therebeneath to regions where it will not injure the furnace.

Figs. 6 and 7 are cross sectional views taken on the lines VI--VI and VII-VII, respectively, of

includes side walls 2, end walls 3, a base 4 and a top 5 composed of suitable refractory material. At one end of the furnace is provided one or more soaking pits or chambers, generally designated 8, including a hearth 1 beneath the pit between said hearth and the top 5 of the furnace structure.

Immediately above the hearth 1, the top 5 is provided with oneor more openings 9 through which ingots may be lowered to rest upon the hearth in upright position, as indicated at a. Covers or tops I0 are slidably mounted for covering said openings during heating. Air-cooled metal chill boxes Il may be provided about the hearth I for cooling rthe latter, as is common practice.

In the opposite end of the furnace is provided a chamber or manifold I2 centrally connected with the stack I3 by a transverse passage I4 and with the atmosphere by a separate passage I5. A pair of reversing valves I6 are mounted for selectively connecting passages Hand I5 with flue banks on opposite sides of the furnace, each flue bank consisting of a plurality of flues, three such flues 'being employed and designated I1, I8 and I9. Regulating valves 20 are provided in chamber l2 for each of said flues for balancing the ow of gases flowing through the flues.

' Flues I1, I8 and I9 extend longitudinally along opposite sides of the furnace structure, being integrally formed therein of suitable refractory,

land terminate in spaced combustion chambers 2l opening into the Vsides of the pit or chamber 5. Said chambers 2l extend vertically between arches 22 in the roof or top 5 of the furnace and bridge walls 22 extending along the sides of the pit at an elevation above the hearth l thereof.

Intermediate the run or longitudinal. extent of each of the ilues I1, I8 and I9, we provide checker chambers 2l, each of said chambers being filled with checker brick as indicated in Figs. 2 and 4. 'I'he furnace may be red in the conventional manner, as by means of burners 25 inserted in the arches 22 of the furnace combustion chambers 2| of flues I1, I8 and I9 into the pit 6, said burners being supplied with gaseous fuel from any suitable source. The operation of the furnace upon the regenerative principle is controlled by the reversing valves I6 to supply `air to one set of ilues Il, Il and I9 through the preheated checkers in chambers 2 4 thereof into the pit 6 while drawing the products of combustion from the pit through the checker chambers 26 of lthe other bank of ues and out of the stack, and then reversing the ow. One such heating cycle is shown by the arrows on the drawings, the other cycle being an exact reversal of that so indicated, and being readily understood by those skilled in the art without further amplification.

Referring particularly to Fig. 2, it will be noted that we have disposed the iiues il, i8 and i9 and their checker chambers 2t completely and entirely above the level of the hearth l of the soaking pit e, and above the level of the layer or bottom 26 of coke breeze or the like upon which the ingots a are placed. Said fiues and checker chambers are also preferably above the tops of the bridge walls 23, so as to prevent overowing molten slag from reaching the checker chambers.

By so elevating the flues and checker chambers,

I we provides. furnace construction which insures against damaged checkers and ues from fugitive or escaping molten slag, which may break through the hearth 7, as by failure of the refractory thereof by heat and by cracking of the chill boxes Il while the furnace is in operation.

Attention is further directed to the disposition of the several checker chambers 26 in the same horizontal plane, thereby enabling a more uniform distribution of checkers and effecting considerable saving in the construction of the furnace over the more complicated structures previously employed. Further, the disposition of the flues Il, I8 and I9 and the checker chambers 24 in substantially the same horizontal plane, provides for a uniform flow of gases therethrough, permitting uniform distribution of the flow of the products of combustion and air through thev series of flues and to and from the soaking pit 6 throughout the longitudinal length thereof.

Figs. to 7 illustrate amodifled form of furnace embodying our invention, wherein the plurality of flues on each side of the furnace is disposed in vertical alignment in the region of and alongside of the soaking pit, said flues having the portions thereof adjacent the stack end-'of the furnace disposed in horizontal alignment for communication with said manifold through the usual regulating valves. Since the parts of the modified furnace are similar to those previously described, except for the arrangement and location thereof, the same have been given like reference characters with' the additionl of the ex-v ponent a thereto.

Ma is disposed in' and along the respective ues il, I8a and I9, and the said checker work and flues are arranged in superimposed relation on each side of the furnace at a suilcient elevation so that the lowermost ues l'la and their checker work are disposed above thehearth and bottom of the pit 6 and above the bridge walls 23B thereof. Hence, fugitive slag escaping through the refractory or brickwork of the "bottom 26a of the furnace or through the hearth "la will flow downwardly away from all of the of fugitive slag from the hearth into said fiues u,

the construction of a furnace of minimum overall width.

Thus, it will be seen that we have provided a regenerative soaking pit furnace embodying fiues and checker work protected against attack and deterioration by slag escaping from the soaking pit, thereby eliminating one of the most destructive actions in furnaces of the character stated. A furnace constructed in accordance with our invention will have a greatly increased life, thereby enabling the continuous use thereof over longer periods of time, without shut-downs and repairs due to the ravages of molten slag.

It is to be further noted that the elevation of the flues and checker work above the level of the hearth and bottom together with the horizontal or vertical alignment of the ues and checker work of the banks thereof on opposite sides of the furnace, provides for a compact and economical furnace construction, with the improved efficiency and operation hereinbefore discussed.

Various changes and modifications are contemplated within the scope of the following claims.

l. A regenerative furnace of the character described including a soaking pit,.a hearth therein for receiving ingots thereon, combustion chambers on opposite sides of and communicating with said pit, means for ring the furnace located adjacent said chambers, means for reversing the ow of gases through the pit and combustion chambers, flues connecting said means and the combustion chambers and having checker chambers intermediate the extent of said ues, the ues and checker chambers being disposed ata sufficient elevation above the hearth to prevent a flow of fugitive slag from the latter into said fiues and checker chambers.

2. A regenerative furnace of the character described including a soaking pit, a hearth therein for receiving ingots thereon, bridge walls on opposite sides of and elevated above the hearth, combustion chambers laterally beyond and above the bridge walls communicating with the pit, means for ring the furnace located adjacent said chambers, means-for reversing the flow of gases through the pit and combustion chambers, flues connecting said means and the combustion chambers and having checker chambers intermediate the extent of said flues, the ues and checker chambers being disposed at\-a sumcient elevation above the bridge walls to prevent a flow yand checker chambers.

As clearly shown in Fig..f6, Athe checker -work t the pit, means for firing the furnace located ad-'" 3. A regenerative furnacegof the character de scribed including a soaking pit, a hearth'therein for receiving ingots thereon, combustion chambers on opposite sides of and communicating with termediate their lengths, said combustion chambers, flues and checker chambers being disposed in substantially the same horizontal plane entirely abovel the hearth level to prevent fugitive slag escaping from the latter from entering the said ues and chambers.

` 4. A regenerative furnace of the character described including a soaking pit, a hearth therein for receiving ingots thereon, combustion cham--v bers on opposite sides ofand communicating with the pit, means for ming the furnace located adjacent the chambers, means for revers-v ing the ow of gases through the pit and combustion chambers, plural series ofl ilues disposed laterally on opposite sides of the furnace connecting the combustion chambers and said reversing means. said fues having checker chambers therein intermediate their lengths, the portions of 4 flues and chambers.

said flues and checker chambers adjacent the pit being superimposed in vertical planes on opposite sides of the furnace and disposed entirely above the hearth level to prevent fugitive slag escaping from the latter from enteringthe said 'JOHN wl CARTER.

ANDREW REED ROWE.

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