US1803007A - Process for heating billets or the like - Google Patents

Description

2 Sheets-Sheet 1 0 was; ....n, un... w\ RN April 28, 1931. H. A. DREFFEIN PROCESS FOR HEATING BILLETS OR THE LIKE Original Filed Dec.

19, 1927 2 Sheets-Sheet 2 mm sN/N N N H. A. DREFFEIN PROCESS FOR HEATING BILLETS lOR THE LIKE Original Filed Dec.

pril 28, 1931.

Patented Apr. 28, 1931 UNITED STATES -HENRY A. DREFFEIN, F CHIC Aero, ILLINOIS P-RQOESS Fett mme BILLETS 0.a Tita L11@ 'original applicata fue@ recenter 1.9., 1w. strat-Noatote, Dtttdtd am this tpplttattttt neemt/fatta a, 192s. seria; in). 316,695,

This invention relates to processes for heating billets or the like, and has among its objectsfto provide a process for eiiicient and satisfactory heating of metal masses such as billets, for example, an eiiicient combustion of the heating gases, and an elicient application of the heat to such metal masses.l

This application is a division of my former application Serial No. 240,990, filed December 19, 1927.

These andother objects will be more fully set out and made apparent in the following specification and shown in the accompanymg drawings in which- Fig. 1 is a vertical section through a furnace designed to permit the practice of my process; g

Fig. 2 is a horizontal section along the line 2 2 of Fig. 1.

In the drawings indicates the bottom or floor of a furnace having the frontv wall l1, side walls 12 and 1 3,`and a root' or top wall composed of the portion 14, portion 15 and the connecting vertical wall 16, as shown in Fig. 1. A rear end wall 1'( is also provided having a charging opening 17u therein.

of the same 'Leading from the rear end wall 17- toward the front wall 11 is a pluralityof spaced supporting walls 20, gradually increasing in height from the rear to the front ends thereof, as shownA in Fig. 1, VBetween the front ends of the supporting walls 20 and the front or discharge end 11 of the furnacel is a raised base portion 21. The raised base portion 21 in the embodiment shown is spaced Jfrom the adjacent ends of the wall members ,2 0 to pro'- vide al transversepassage 22 across the furnace, certain of the walls 2O being extended closer to the base portion 21 than the others, as indicated by numeral 20a. of

Located in the front of the base portion 21 preferably in alignment with the 'passages between the walls .20,is aplurality of'air nozzles 24 communicating through'suitable pipes 24"i with an air line 24-, control valves 24c being provided -for each'o-f the supply pipes 24a. Y

At the juncture ofthe front wall of the base portion 21 with the side walls of the furnace are provided vertical passages or recesses 2.1@ for a purpose hereinafter described.

Trackways comprising water cooled tubular members 23 or the like are mounted on tliesupporting walls 20 and base portion 2K1. The base portion 21 is downwardly inclined at 21alat its front portion, and the tubular members 23'are similarly inclined at 23?, thus providing a downwardly inclined trackway 'at the discharging endI ofthe furnace,

theV same leading to a discharge opening 1 1a normally closed by the pivoted gate or door 26,` At the front of the furnace adjacent the discharge opening 1-1a is a series ofrollers 28 orother conveying means upon which billets A may be discharged from the :furnace under force of gravity.

The roof portion 14 is raised and oiset Withrespectto the lowerrear end portion 15 as viewed in Fig. l of the drawings, and` with the 'vertical connecting wall 15, the front wall 11, the floor 10 and supporting base portion 21 is formedwhat is termed a laboratory or combustion and heating chamber into which the billets A are charged andfroin which they are discharged after heating.

' In the front wall 11, opposed to the vertical wall 16, lis a plurality of burner openings in which are mounted nozzles 31 of'refractory material or the like, the burner openings and nozzles leading from a gas chamber 38 into which gas is fed from a supply duct 35, the vsupply of gas being controllediby an adjustable valve 86 (seeFig. 1).. Projecting into the gas chamber 33, in alignment with the nozzles 31, is a plurality of air supply pipes 37', preferably of heat resistant steel or the like, the same attheir dischargeends terminatingshort of the nozzlesl. These pipes 37 are in connection withfan air supply duct 39, through pipe elbows 37g. A' slide valve generally'indicated by numeral 4Q-`is provided for each of the pipes 37 to control the air supply thereto and through'.V Itwill be apparent that theair being delivered under-pressure through pipes ',31vvill mix with the gas for combustion `and discharge the mixture through the nozzles 81 into the llaboratory, which I have designated bynumeral 45. Control of combustion and heating across the laboratory may be effected byregulation of the valves 40, as will be apparent. The air duct 39 in the embodiment shown, leads from a species of preheater or recuperator indicated in dotted lines by numeral 47 in the stack 48, a fan or blower 50 being utilized to force air through the recuperator 47, thereby utilizing the waste gases to effect a preheating of the air before it is delivered to the pipes 37. rlhe pipes being constructed of heat resistant material will permit the use of preheated air in the manner described.

The lower roof section 15 is spacedA closer to. the track members 9.3, and constitutes in 'effect "a low ceiling extension 53 of the furnace in which initial or preheating 'of the billets is effected by the outwardly flowing gases. Adjacent the uncture of the labf oratory and the reduced furnace portion 53 is provideda plurality of air supplynozzles vor pipes 55 connected with a supply line 56, and directed toward the laboratory.v

`At the charging or rear end of the furnace is alsoprovided a plurality of air nozzles or pipes ,58 connected with a supply line 59, andV also preferably directed toward the interior .of the oven. Y

Leading downwardly from the bottom of the `furnace adjacent the charging opening '17al is an exhaust duct 60 which leads to the angular-ly disposed duct portion 61 in turn leading to a stack connection 48"-. Y

lA transverse opening 65 is provided beneath the track members 23 in the laboratory to permit cleaning and circulation of the heating gases. Similarly transverse open- -ings 67 are provided in the supporting Vwalls 2O to provide a transverse circulating and clean-out passage rearwardly of the passage i v65. vNea-r the charging or vrear end of the furnace small baffles or abutments 68 project upwardly between the outermost supporting walls 20 and the furnace side walls and'a similar abutment 68 is located between the ,central supporting walls, these serving to favor the flowV of gases through the tunnels beneath the billets A.

YVIn the practice of my process of the apparatus described`above,the gas for combustion is supplied through ducts 35 into the `chamber 33, and the valves L4Ofare adjusted Vtoainsure proper deliveryr of air through pipes 37.'.This air commingles with and Vcarries the gasfor combustion through nozzles 31 and themixt-ureisrburned in the lab'- oratory or chamber 45. It is desirable to Vgases with the billets A. The air is pree heated to a desired degree in its passage through the pieheater or Vrecuperator 47 under propulsion of the fan 50.

The moving gases, including the burning gases and gases of combustion, impinge against the wall 16, which first translates their velocityinto pressure and thereafter from pressure into velocity ina direction substantially at right angles to the original direction of iiow, and such gases are directed downwardly upon the billets or other articles as they are entering the laboratory, at which point they are relatively cool as contrasted with the final temperature at the time of the discharge from the furnace. While I find it desirable to use a substantially vertical wall 16, its inclination may be varied from the vertical, and the check or retarda n tion of the velocity and the ensuing Vcirculation or recirculation of the gasesy over and .around the billets may be assisted by air Vthe end wall 11` of thefurnace over and around the billets in the laboratory. The alcoves or side passages 66 permit downward flow of some of the gases tothe passageway/s beneath the billets and the transverse passage 67 permits transverse distribution of such gases. `Similarly the recesses' 21a in the raised base portion also permit fiow of some of the heating gases to the passages beneath the walls 20'beneath the billets. The recirculated gases otherwise flow over and around the billets, as stated, toward the furnace wall 11 and are picked up and commingle with the incoming fuel mixture and are again directed toward the wall 16.

The flame of combustion, occurring, in the main, somedistance above and substantially parallel to the billets, also radiates heat which impinges upon the billets so that the A heating effect in the laboratory results from the direct contact of the gases and the radiant heat, anda constant recirculation of the gases is maintained, during which continuous mixture of such gases with the incoming fuel mixture occurs. Also thev velocity of the incoming fuel mixture and gases is greatly reduced, permitting retention of such gases for a longer period of time inthe laboratory. if.

The recirculated gases which have passed over the relatively cool billets contribute to the reduction in temperature of the incoming fuel mixture to lower its temperature, the temperaturek of such recirculated gases being at the same time properlymaintained.

As a consequence offall ofthesefactors I lasciano? of suoli billets at a temperature closely ap-v proaehing that of Vthe temperature of the gases in the laboratory. This is the ideal condition Sought in this art, and not obtained by present day apparatus or processes. l rllfs enables me to usefthe radial heat of the burning gases during their flow at the' upper portion of the laboratory as Well as the heat of the reciroulating gases by direct contact with the billets during the'reyerse lioW-v The ability to maintain a Substantially uniform temperature throughout the laboratory enables Ine to readily design my apparatus for the capacity desired', and furtherenables me to obtain the very ldesirable soa-king actiOn Which results in substantially unifollllly heated billets or metal masses.

Also, I. am enabled by regulating or properly determining the fuel and air supplied tov the laboratory, to maintain a pressure therein at leaste'qua'l to o r in excess of atmospheric pressure which prevents inltiation or leakage of air into the laboratory through, the discharge` of. ll.a or elsewhere, a highly desirable result When air ie Supplied through nozzles 55 it also is preferably directed substantially parallel tothe nntlernaaeing billete, and einee I iind it desirable to'supply fuel `in considerable egrcess of that which will bur-n` with the air initially Supplied in order toy maintain a strong reducing' atmosphere in the labora-- tory, this ,eeeondary air throng-h, nozzles 5,5

will eenlniinsle With the unbnrned fuel 'and contribute to the heat in the laboratory and Salvage. the heat content of fue-l which would otherwise be wasted. Since the secondary air through. nozzles 5.5 iS introduced Substantialn ly parallel. te the billetes again there ie ne direction. of the burning gasesoruneoinbned air Clireetly upon, thebillets and danger of oxitliaaton ielasain ebyiated.

The laboratory, beingof relatively great Size and length, permite substantial expansion of the saseaftlne also. contributing to the cheek of the velocity thereof, and as stated, l alla enabled and find it Clelabltt@ maintain a pressure in, the laboratory equal to that of the surrounding atmosphere or 'slightly in excess thereof.

The enlarged laboratory and the retention of the gases for a period of time therein permit the eifectuation ot substantially complete combustion for those gases for which there is sufficient air to, support such combustion', nlnet. I. tad desirable in praetiee,

As stated, l find it desirable at least in some instances to introduce a preponderant excess oi gas for combustion, for example, as high as of excess gas, and thereby maintain a strongly reducing atmosphere in the laboratory Where the billets are subjected tothe greatest heat, thereby substantially preventing oxidization ot' such billets.v Coinpletion of combustion before contact of the gases With the billets inthe chamber l5 is also desirable, as it is Well known that com bustion taking yplace closely adjacent the billets resultsin thek formation of scale and other detrimental substances upon such billets.

rllhe billets are advanced fromthe charging opening 17 up and along the track members by any desired means, the movement imparted being that desired to permit' proper heating and penetration of the heat into and l supply ofrthe billets tor subsequent operations. Y

`The travel of the billets through the laboratory 4,5, is at a suiiciently slou7 rate to permit complete .penetration of the greater heat n which obtains there. As the billets reach the inclined portions 23,a of the track they slide by gravity downwardpast the swinging gate 2G and are deposited upon the transversely arranged conveyor rolls-28 for passage to l.

subsequent treatingstatio-ns. i e

'.lheprorision of a plurality of transyersely arranged air inlet pipes 37 eachV with valve control permits regulation .or control of the heat across the laboratory and affordsV the operator an opportunity to control the lrlteral distribution of the beat therein.`

' he introduction of an excess of, combustible gas into the laboratory l5 over that oapable of combustion with the air Vsupplied also lowers the average flame temperature as Well as maintains a reducing`I atmosphere From the laboratory chamber l5 the gases Hou? through the reduced furnaeeportion 53, both below and above the billets. The restricted chamber compacts the outwardlyiiowing gases and brings them. closer tothe billets,1 whereby the heat in suehgases is more etlioiently applied for the preheat-ing of such billets.

Air may be supplied through nozzles24 i.

ieu

,les

Yso

through the passages between the Walls 20, as will be obvious. V V

Air may also be supplied through nozzles 'at the charging opening 17a, Which Will effect combustion of any. unburned gases prior to their discharge in the stack, and the jets of fair through the nozzles 58' will assist in preventing leakage of the gases out through the charging opening 17a. Any supplemental combustion resulting from the introduction of air through nozzles 58 boosts the heat of the burned gases before they are delivered to the recuperator 47 so that the heating effect of such gases is salvaged and assists materially in the preheating of the air for combustion.

IY believe it desirable to operate the nozzles 55 when a richer mixture is delivered into the laboratory, so that the heating eect of the greater amount of unburned gas is availed of before the passage of theV gases through the reduced furnaceV portion 53, It is probable that my process may be carried out as toits essential and novel steps in apparatus differing from that illustrated in the drawings and described in the specilication,and` I do not Wish to be restricted to such apparatus'nor tothe process as described except as the appended claims define the saine under fair interpretation.

What I claim is: n i

1. A process of the class described consisting in continuouslyV passing billets through a preheating chamber, thereafter into and V through an' enlarged main heating chamber andoutof a discharge opening from said main chamber, supplying fuel and air ,at substantial velocity Ato said main chamber above said billetsadjacent the point of discharge thereof and in spaced relation thereto, thecombustion of said fuelbeing substantially effected out of Contact With said billets but in such `wise as to subject the latter to direct unobstructed radiant heat, at least a portion of the gases of combustion beingv thereafter reversely circulated in contact With said billetsand into admixture with the incoming fuel and air. v n v 1 2. A process of the class described consisting in continuously passing billets through a preheating chamber, thereafter into and through anenlarged main heating chamber and out ofa discharge openingV from said main chamber, supplying fuel andair at substantial velocity to said mainfchamber above said billets adjacent the point of discharge thereof and yin spaced relationV thereto, the combustion of saidfuel being substantially effected out of contact With -said billets but in such Wise as to subject the latter to direct unobstructed radiant heat, at least a portion of the'gases of combustion being' thereafter reversely circulated in contact With said billets and into admiXture With the incoming fuel and air, a portion of the gases from said laboratory being conducted through said Ypreheating chamber.`

3. A process of the class :described consisting in continuously passing billets through a preheating chamber, thereafter into-andi :through an enlarged main heating chamber and out of a discharge opening from said main chamber, supplying fuel and air at substantial velocity to said mainchamber above said billets ladjacent the point of discharge thereof and in spaced relation thereto, the combustion of said fuel being substantially effectedout of Contact With said ,billets but in such Wise as to subject the latter to directv unobstructed radiant heat, at least a portion of the gases of cominto and through an enlarged main heating iso chamber and out of a discharge opening from Y Y said main chamber, supplyingl fuel and air at substantial velocity to said main chamber above said billets adjacent the point of discharge thereofand in spaced relation thereto, thev combustion of said fuel being substantial'lyv effected out of contact With said b-illetsbut in such Wise as to subject the latter to Adirect unobstructed radiant heat, at least a portion ofthe gases of combustion being thereafter reversely circulated in contact v With said billets'and into admixture with the incoming fuel and air, a portion of the gases from said laboratory being conducted through said preheating chamber, the supply and combustion of saidfuel and air being iom controlled to maintain atleast atmosphericv i pressure in said laboratory. j

5. A process of the class described 'consisting in continuously passing billets throughy a preheating chamber, thereafter into'and through an enlarged main heating chamber' and out of adischarge opening from said main chamber, supplying fuel and lair at substantial velocity to said main chamber above said billets adjacent the point of discharge thereof andin spaced relation thereto, the combustion of said,` fuel being substantially effected out of contact -With said billets but in such Wise as to subject the lat ter to direct unobstructedradiant heat, at least a portion of the gases of combustion being thereafter reversely circulated in contact With said billets and into admiXture With the incoming fuel and air, a portion of the gases from said laboratory being conducted through said preheating chamber, and supplying additional air to admix With and oppose the flow of gases through said preheating chamber whereby combustion of unburned fuel will be eected.

6. A process of the class described consisting in continuously passing billets through a preheating chamber and therefroin into and through an enlarged main heating chamber and from said main chamber out of a discharge opening adjacent the end of said chamber opposite t0 the entrance point, supplying and burning fuel and air in said laboratory above said billets, said fuel and air being supplied thereto in spaced relation to said billets adjacent the discharge end of said main chamber, the combustion of said fuel and air being substantially effected out of contact With said billets but in such Wise as to subject the saine to direct unobstructed radiant hea-t of said combustion, passing a portion of the gases of combustion through said preheating chamber and re- Versely recirculating the remainder of said gases in said laboratory in contact With said billets and into adinixture with the incoming fuel and air.

In Witness whereof, I hereunto subscribe my name this 31st day of October, 1928.

HENRY A. DREFFEIN.

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