US2443244A - Jet ejector furnace - Google Patents

Description

June 15, 1948. HESS 2,443,244

v JET EJECTOR FURNACE 7 Filed Jan. 2-. 1947 I 3 Shets-Sheet 1 INVENTOR FREDER/C O. Hz'ss June 15, 1948.

F. o HESS" JET EJECTOR FURNACE 3 Sheets-Sheet 2 Filed Jan. 2, 1947 INVENTOR FR- LJER/c O. Hsss n h nv ATTORNEY mmummmnl llllllllllllllll'lillllll.

June 15,1948. F, 0. F555 JET EJECTOR FURNACE,

3 Sheeis-Sheet 3 Filed Jan. 2. 1947 INVENTOR FEEDER/C 0.. Hsss Patented June 15, 1948 2,4433 .m'r mnc'ron FURNACE Frederic 0. Hess, Philadelphia, Pa., assignor to Selas Corporation of ,America, Philadelphia, Pa., a corporation of Pennsylvania Application January 2, 1947, Serial No. 719.682

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The present invention relates. to work heating furnaces and particularly to continuous furnaces of a type adapted for use in heating small metallic articles, or work pieces,-up to a relatively high temperature as the articles are progressively advanced through a furnace heating zone from a charging station or furnace inlet to a discharging station or furnace outlet.

The general object of the invention is to provide improved means for ejecting heated, articles from the furnace in which they are heated. A more specific object of the invention is to provide .a continuous furnace of the abovementioned type with a work ejector in the form of a fluid fuel burner located in the discharge station portion of the furnace, and means for operating said burner to eject each article when moved into a predetermined discharge position by then discharging a high velocity jet of hot gaseous material against the article. Advantageously, the force of the jet impinging against the work ejectingoperations.

each article to be ejected, is great enough to move the article of! the travelling carrier and into a discharge chute or other device through which, the article moves away from the furnace.

In the preferred form of the present invention hereinafter described, the work ejection burner is of the type disclosed and claimed in my prior Patent 2,367,119, granted January 9, 1945, and comprising a combustion chamber and a wall having a restricted outlet formed wholly or largely of refractory material, and into which combustible fluid and air for combustion are supplied to maintain the desired combustion chamber pressure. In said preferred form of my invention, the said ejector burner forms part of the furnace heating system and is advantageously associated with means for quickly varying the pressure maintained in the combustion chamber of the burner, so that the burner may be operated to maintain the relatively high combustion chamber pressure needed for work ejection purposes during the brief recurring periods in which the heated work pieces or articles are ejected from the furnaca-gnd may be operated with a lower combustionchamber pressure during the longer, periods alternating with the work discharging Periods.

During the intervals between successive work ejectingoperations, the fluid passed into the combustion chamber of the ejector burner preferably consists of combustible gas and air premixed in substantially the proportions required for complete combustion. In some cases, the same mix- In other cases, the proportion of air to combustible gas supplied to the ejector burner may be substantially greater than is required for complete combustion at all times, or at least during the work ejecting periods. One effect of thus continuously or intermittently diluting the combustible mixture supplied to the ejector burner, is a reduction in the overall or average heating eflfect of the ejector burner, and the avoidance of overly large local heating effects, which may be injurious to the furnace and the work. Such heating effect reduction maybe especially important where the work pieces are of relatively large size, and the work ejecting force must be correspondingly great.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter-in which I have illw trated and described. preferred embodiments of theinvention.

0f the drawings:

Fig. 1 is an elevation, partly in section, of an automatic furnace embodying the present invention, the section being taken on the broken line i--| of Fi 2;

Fig. 2 is a horizontal broken line 2--2 of Fig. 1;

Fig. 3 is a partial sectional elevation taken on the line 3-3 of Fig. 2;

Fig. 4 is a partial vertical section taken on the line 4-4 of Fig. 2; and

Fig. 5 illustrates a modified form of supply piping for the ejector burner.

The furnace structure shown in the drawings comprises a stationary furnace body A mounted on a stationary base or supporting structure B, and a rotary heart-h C mounted on a rotatin supporting structure D. The hearth C and its supporting structure revolve about a vertical axis section taken on the and the refractory body portion of the hearth structure forms a movable bottom wall of a furnace chamber E formed in the stationary body A of the furnace and extending circularly about said axis. The chamber E is not a complete annulus, but is in the form of an arc of 325 or so, with its ends separated by a charging station F. As shown, the charging station F comprises a notch or space formed in the portion of the genture may be supplied at higher pressure during 86 erally cylindrical stationary furnace body A above or blocks of so-called insulating materials.

the level of the hearth C, and extending from the periphery of the furnace. body inward to the wall 'of a central vertical chamber G, and extendingupward to the top of the furnace body portion A from the level of thetop of the hearth C.. The furnace body A and hearth C may be constructed in accordance-with the usual practices of the furnace art, mainly of masonry, but ordinarily,

. and as shown, with an outer casing of sheet anchored in the formed with spaced radially extending I." at its upper'edga. Iach notch L'. forme.a cradle or seat in which a work piece ll'may be mounted with its, axis extending radially away from the vejf "ic'al axis of the furnace. "The work pieces M mil like various forms and be made of various materials, for example, they may be short steel cylinders which, aiter'v sem heated, are worked into valve parts-by extrusion. While each work seat L' is being advanced by the rotation'of the hearth through the charm station I", a work piece M-mayjbe placed therein manually, or by automaticfeeding mechanism, not shown. Each work piece 14 after being mounted inthe corresponding seat L, is moved by the rotation of the Jiearth C law the furnace chamber E, and

chamber E through; furnace wall burners H'- mounted in burner openings H formed in the roof of the chamber E, and receiving air and combustible gas, preferably premixed in the proportions required for substantially complete combustion, from branches 1' of supply piping at the top of the furnace body A. The burners H may advantageously comprise suitably channelled bodies of refractory material with open combustion spaces at their lower ends, and are preferably of the type disclosed and claimed in-my prior .Patent 2,215,079, or September 17, 1940. With such burners, much of the .heat generated is transmitted from the burners in the form of radiant heat. 1

The products of combustion'of the combustible I mixture supplied to the burners H pass away from the chambers E through vent channels J formed in the furnace body A. As shown in Fig. 4, the channels J have inclined lower end porthrcugh the',; major portion of the length, c

the'latter-andthence into the work election or discharge station or chamber N. The latter comprises an opening or spacein the masonry of the furnace my; A which extends across ,thefurrntc'e chamber from the inner wall of the latter to the peripheral portion of the furnace-body. As

shown, the discharge station N is separated from the adjacent side of'the charging or loading station F by a'relatively small angular distance.

When each work-object passing into the discharging station reaches a predetermined position thereixi, it is subjected to the displacing action ofa. radially directed =jet acting against: the

- innergend o! the work piece M and strong enough tions extending upwardly and outwardly away from the furnace chamber E at points distributed along the length of the latter and intermediate the burners H. ,The. vertical upper portions of the vent channels J extend to the top of the furnace structure.

- The rotary hearth 0 comprises an annular body of refractory material received in a slot formed in the furnace body A and extending circularly about the furnace axis, and extending downward from the bottom of the chamber E to the lower end of the furnace body A. The refrac tory portion of thehearth C is directly supported by a radially enlarged upper portion of a rotatable metallic supporting structure D. The latter comprises a center column B mounted on a stationary base or pedestal DA to turn'abo'ut-the vertical axis'of the furnace. As shown, the supporting structure D is normally-maintained in continuous rotation by motor driven means com- 1 prising a speed reducing gear mechanism K. The

later includes a horizontal input shaft carrying a pulley K driven through a belt K by a driving motor K The speed reducing gear mechanism K includes a vertically disposed output shaft K carrying a spur gear K in mesh with a large diameter gear D coaxial with and forming a part of the rotating hearth supporting structure The rotary hearth C isprovided with an uprising annular work support L suitably shaped to support the articles of work pieces M to be heated.

As shown, the support L comprises vertically-disposed refractory blocks having theirlo'werends to move the work piece out of its supporting seat 'L'. In thejform of construction shown."when each work object is thus displaced from its supporting seat L' it is movedinto the upper inlet end of a downwardly inclined chute'or g'uidevlfay 0 having its lower discharge and at the outer side of the furnace body A. Advantageously, and as shown, theouter side of the ejection station space N is normally closed except for the'passageway through the chute O by a wall portion M which .may=form a separable part of the usual metallic casing surroundingthe masonry of the furnace body A.

In the preferred formof the invention illustrated, the fluid Jet by which each work piec M is moved out of its seat L' and into the upper end of the chute O, is a jet of products of combustion, which maysometimes be mixed with burning gases and which is discharged through the outlet P' from the combustion chamber 1- of aneiector burner P. As shown, th burner? is horizontally disposed between the upper endof the discharge chute O and the central chamber G, and theaxis of the outlet passage P is horizontal and extends radially away from the furnace axis and may well be approximately coincident with the axis or the work plead-M at the instant at which the. pressure in the; bumer' chamber 1 is increased to I move the wogk piece off its support L and into the dlschargefchllte O.

As willlbe' apparent, the means for suppl in air and combustible fluid to the burner chamber P?, and for regulating the pressure in that cha n ber, may take various forms.

ment shown in Fig. 1,a preformed mixture'cf gas and airis continuously supplied to. the inlet P of the burner P through a pipe Q at a pressure regulated by valve connections interposed between the pipe Q and a supply main QA. The pipe Q extends downward into the chamber ,G from a level above the top. of the furnace to the level of the burner inlet P These valve connections between the pipe Q and main 'QA,"as

m m g,

In th iarrange asap shown in Fig. 1, comprise a pipe section including a throttle valve R and a second pipe connection including a cut-oi! valve 8. The valve R is adapted to pass combustible mixture from the main QA into the valve chamber P at any relatively low rate which may be found desirable for operation during the intervals between the periods in which the burner P is used as a work ejector. The relatively low rate at which the combustible mixture is then supplied-throughthe valve B may be varied, and the normal low pressure in the valve chamber P correspondingly varied, by adjustment of'that valve. The valve 8 is mounted in a pipe section forming a by-pass about the valve R. The valve 8 is of a type adopted to be rapidly adjusted from a normally closed condition into a wide open condition. In its wide open condition the flow capacity of the valve 8 is suflicient to effect an almost instantaneous increase in the pressure in the burner chamber P to the amount required to create a discharge jet eflective to move the work piece M on which the jet impinges out of its seat L' and into the discharge chute 0.

Advantageously, the valve S is automatically actuated to momentarily increase the pressure in the ejector chamber 1? as each work support L is moved into position in front of the burner P. For example, the valve 8 may be operated through mechanical or electrical connections by the rotating structure D. Thus as diagrammatically valve to the piping I, and thereby to the furnace roof burners H which supply most of the heat utilized in heating the furnace chamber El. Alternatively, the valves R and S may receive combustible mixtures from separate mains or supply pipes. Thus, as shown in Fig. 5, for example, a main QB may supply combustible mixture at a relatively low pressure to the pipingI through which the roof burners H are supplied, and to the inlet of the pipe section including the valve R, and a pipe QC may supply a combustible mixture at a higher pressure to the valve 8. In such case, the valve R need not be adjusted to create a ubstantial drop in the pressure between the main QB and the pipe Q. The fluid supplied to the burner P through the valve S from the main QC may consist of air and gas mixed in the propor tions required for complete combustion, or it may consist of a mixture of air and gas containing substantially more air than is required for the complate combustion of the gas, or in some cases the I particular furnace form and design shown inthe' drawings, the full width of the furnace chamber- E, shown at the left hand side of Fig. 1, is a little less than one-half foot, and the radial distance from'the center of the furnace chamber E to the furnace axis is about two feet. The hearth is provided with twenty-four work supports L, each adapted to support a work piece M in the form of a steel cylinder 1 inch in diameter and 1% inches long, and the hearth C makes one revolution every four minutes so that work pieces M are normally ejected at tensecond intervals. The furnace chamber E is so heated that in the period of a little more than three minutes required for the movement of each work body M through the furnace chamber E from the charging station F to the discharge station N, the work piece attains a forging temperature of approximately 2150" F. To this end, the temperature of the atmosphere in the chamber E may be maintained constant at about 2500 F.

As -will be understood, the foregoing structural and operative data is given by way of example and illustration and not by way of limitation, and the dimension, temperatures and rate of operation may be widely varied as conditions make desirable. For example, to attain the same discharge temperature of 2150 F., the heating temperature or the heating period would have to be increased if the work pieces were steel cylinders 3 inches in diameter and 3 inches long, as they may be in some cases. Ordinarily, a furnace for heating articles of such size should have greater dimensions than those specified above. When the articles heated are made of a material other than steel, such for example as magnesium, the flnal temperature to which the article is heated, and its rate of heating, may be quite different from those desirably employed in heating steel articles.

To eject steel work pieces of the character above mentioned, the ejection pressure in the burner chamber, P may well be of the order of 2 pounds above the pressure of the atmosphere and the velocity of the jet discharged through the ejector burner may well be about 1200 feet per second. The jet force which must be applied to the work piece being ejected from the furnace increases, of course, with the weight of the work piece. An increase in the work piece weight may be taken care of by increasing the volumetric capacity of the burner so as to increase the amount of fluid discharged through the port P without necessarily requiring any increase in the pressure in the chamber P or in the jet velocity. However, an increase in the pressure in the'chamber P of a burner of given size, will'increase the work discharging energy available in the jet discharged through the outlet of the burner.

In the use of the furnace and heat forging temperatures of the order of those mentioned above by way of example, provisions should be made for cooling parts as required, to avoid objectionable overheating. Thus, as indicated in the drawings, the masonry wall of the central chamber G in the furnace body may be provided with a wall lining U, and water walls U may be provided at the vertical outer edges of the masonry portions at the sides of the charging station F, and the wall of the discharge chute 0 may be formed with water cooling passages. v

To prevent air leakage or gas leakage through the joints between the abutting masonry portionsof the rotating hearth C and furnace body A, inner and outer annular sand seals W and WA may be provided as shown in Fig. 1. As shown, the seal W comprises an annular trough W' supported by the portion of the stationary framework structure 13 directly beneath the central portion of the kiln, and the seal WA comprises an annu- 'sonl'y atone side of said station.

lar trough W carried by the rotating structure D. A metallic cylinder Whaving its upper end attached to the rotating hearth structure ad- Jacent the inner edge of the latter extends down intq the trough W of the seal W. Similarly, a metallic cylinder W attached at its upper end to the stationary body portion of the furnace. extends down "into the outer sealing trough w". Sand is supplied to the inner sealing trough W at the inside of the angle W through-inclined chamnels I formed in the stationaryportion of. the oven masonry, and open at their upper ends to the lower end or the central chamber G. Sand to maintain the outer seal may be passed intothe cuter trough W through an inclined channel XA opening at its upper end into the charging station space F through the portion of the ma- As shown in Fig. l, a flre check Z is located in each of the pipe branches receiving combustible mixture from th main QA.

While in accordance with the provisions of the statutes. I have illustrated and described thev Having now claim as new and desire to secure by Letters Patent, is:

i. A furnace structure formed witha heating chamber and with-a work piece discharge pas,-

sage having its receiving end open to said chamber, heating means for said'chamber including a fluid fuel burner structure having a combustion chamber with a restricted outlet opening into'said heating chamber, and means for supplying combustible fluid to said combustion chamber at a relatively high pressure to thereby discharge through said restricted outlet a heated fluid jet adapted to move a work piece from said furnace chamber into said discharge passage. 1

2. A furnace structure formed with a heating chamber and-with a workpiece 'discharge passage, having its receiving end open to said chember, heating means for said chamber including a fluid fuel burnerstructure having a combustion chamber with a restricted outlet opening into said heating chamber, and means for intermittently supplying combustible fluid under a relatively high pressure to said combustion chamber to thereby effect the discharge through said restricted outlet of a heated fluid jet adapted to impinge against a workpiece in said heating chamber and move said work piece into said discharge passage.

3. A furnace structure formed with a heating chamber andwith a work piece discharge passage having its receiving end open to said chamber, heating means for said chamber including a fluid fuel burner structure having a combustion chamber with a restricted outlet opening into said 1 heating chamber, means for supplying combusv tible fluid to said combustion chamber at a relatively low pressure, and means for intermittently supplying combustible fluid under a higher pressure-to said combustion chamber to thereby effeet the discharge through said restricted outlet of a heated fluid iet adapted to impinge against 'a work piece out of said furnace chamber a work piece in said heating chamber and move said work piece into said discharge passage. 4. A continuous furnace comprising a structure formed with spaced apart charging and discharging stations and with an elongated furnace chamber extending between said stations and having at said discharging station an outlet from saidchamber-for work pieces, a work conveyer operative to move work pieces through said chamber from said charging station to said discharge station, heating-means for said furnace chamber. including a fluid fuel burner located at said discharge station and comprising a combus tion chamber with a restricted outlet directedtoward the portion of the furnacechamber space occupied by each work piece when moved into said discharge station by said conveyor, and means for supplying combustible fluid to said combustion chamber at a relatively high pres sure to thereby discharge through said restricted outlet a fluid jet adapted to move a work piece out of said furnace chamber portion and-into said discharge passage.

5. A continuous furnace comprising a structure formed with spaced apart charging and discharging stations and with an elongated furnace chamber extending between said stations and having at said discharging station an outlet from said chamber for work pieces, work conveyor means operative to move work pieces through said chamber fromsaid charging station to said 'dis-,

charge station, heating' means for said furnace chamber including a fluid fuel burner located at saiddischarge station and comprising a combustion chamber with-a restricted outlet directed to- I ward the portion of the furnace chamber, space occupied 'by each work piece when moved into said discharge station by said conveyor, and means including a supply valve opened intermitteutly by said work conveyor means for supplying combustible fluid to said combustion chamber at a relatively high pressure when said valve is open and thereby effect the discharge through said restricted outlet of a fluid jet adapted to move a work piece out of said furnace chamber 6. A continuous furnace comprising astructure formed with spaced apart charging and dis-' charging stations and with an elongated furnace chamber extending between said stations and.

having at said discharging station an outlet from said chamber for work pieces, work conveyor means operative to move work pieces through said combustion chamber at. a relatively low" pressure comprising a supply conduit continuously open to said combustion chamber and means for intermittently supplying combustible fluid at a higher pressure to said'combustion I chamber comprising a supply valve opened and closed by work conveyor means to intermittently maintain a relatively high pressure in said cont bustion' chamber to thereby discharge through said restricted outlet a fluid jet adapted to move I V .mr-

tion and into-said discharge passage. FREDERIC O. HESS.

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