US1545496A - Furnace and method of operating the same - Google Patents

Description

July 14, 1925.

INVEN'T'ORS 2 Sheets-Sheet- 1 v L. c. JAcoBUsET AL FURNAcE AND METHOD 0E OPERATING-THE vSAME V Filed June so, 192s l .NWNL

Julv 14, 1925.

FURNACE AND METHOD 0F OPERATING .TI-IE' SAME JACOBUS ET A 2 Sheets-Sheety 2 Filed June 30, 1925 m ML INVENTORS 4Patented July 14, 1925.

UNITED STATES PATENT OFFICE.

I LANGFOBD C. JACOBUS AND JOHN H. GILLOOLY, OF SEWICKLEY, PENNSYLVANIA, AS- BIGNORS TO' TATE-J ONES lAND COMPANY, INCORPORATED, OF PITTSBURGH, PENN- SYLVANIA, A CORPORATION OF PENNSYLVANIA.

I FUBNACE AND METHOD F OPERATING THE Sm Application llled June 30, 1923. Serial No. 648,795.

To all whom t may comm.

Be it known that we, LANGFORD C. JA- CoBUs and JOHN H. GILLooLY, citizens of the United States, residing at Sewickley, 5 county of Allegheny, and State of Pennsylvania, have invented a new and useful Improvement in Furnaces and Methods of Operating the Same, of which the following is a full, clear, and exact description.

. The present invention `relates broadl to furnaces, and more particularly to eat treating furnaces and method of operating the same, although its usefulness in this respect is not limited.

By the term heat treating as used throughout this specification .and claims, we intend to cover not only straight annealing, heating for quenching, draw backl and the like, but' also melting where thel furnaces and hearth constructions are such as to be suitable for this purpose.

At the present time, in automobile work, for example, it is necessary to have relatively large capacity furnaces adapted to i!! be operated at comparatively high temperatures, such as 1400 tol1800 degrees F., for heating for quenching, in order to harden the work being treated, and also other furnaces adapted to be operated at lower temperatures, such as 800 to 1100 degrees F., for the draw back or tempering. Furnaces are lnecessarily-constructed with regard to the temperature at which they are to be efficiently operated, and at other temperatures the efficiency not only decreases, but the maintenance of a given temperature becomes extremely diliicult, if not impossible. Also, at such other temperatures, the forced firing, if a low temperature furnace is to be operated at a higher temperature, destroys the furnacestructure; or the firing at a reduced temperature where a high temperature furnace is to be operated at a lower temperature, results in inefficient combustion.

It is apparent, however, from a `standpoint of installation ex ense, as well as operating costs, that hig ly desirable results would be obtained if a single furnace could be eiciently used over the entire range of temperatures ordinarily dealt with in this art. v This invention has for one of its objects a furnace of this character, together `distance of the roof.

with improved means' for operating the same.

In the accompanying drawings, there is shown for pur oses of illustration only, one

- and operation disclosed without departing vfrom the spiritof the. invention or scope of our broader claims.

In the drawings:

Figure 1 is a transverse sectional view through a furnace constructed in accordance with the present invention,

- Fi ure 2 is a longitudinal vertical sectiona view through the furnace illustrated in Figure 1, and

Fi re 3 is a detail sectional view illustrating a slightly modified form of constructlon.

It will be understood that the drawings disclose a side fired furnace of the car type particularly adapted for heat treatlng or annealing. In this furnace there are provided the usual side walls and roof, which may conveniently be constructed of lire brick 2 and insulating brick 3. The cars, where they'are used, may be formed with a supporting layer of fire brickl 4 anda carrying surface of vitrified brick or other suitable material 5. The cars may be sealed to protect the running gear,.in any well known manner.

. Within the furnace there `are, provided baies 6 extending longitudinally thereof and upwardly to withina predetermined The spaces 7 provided between their upper ends and the roof represent the maximum area through which the combustion gases have access to the effective heating chamber 8 of the furnace. These areas must be calculated in accordance with the temperature conditions to be maintained within the furnace, and the position of the burners.

In accordance with the present invention, .the 4burners are arranged in novel man ner, there being an upper set of burner opemngs 9, and alower set ofsimilar openings 10, all communicating with the combustion chamber 11 between the respective walls and ballles. With form of furnace, it is .ture conditions result.

contemplated that the burners cooperatin with the upper set 'of o enings shall be use for maintaining the igher temperatures, while the burners cooperatin with the lower set of openings shall be use for maintaining the lower temperatures in the effective heating chamber 8.

It is well known that in the operation of furnaces, a given minimum local combustion temperature must be maintained in order to insure efficient combustion either with liquid or gaseous fuel. This minimum temperature, together with the relative proportioning and relationship of the parts is such that in using the upper set of burners, it is only possible to eciently maintain temperatures,

.for example, of from 1400 to 1800 degrees F. within the effective chamber 8. If this minimum local temperature is reduced, inefcient operation and non-uniform tempera- 0n the other hand, with the lower `set of burners, the given minimum local combustion temperature and the relationship ofthe parts is such that the ower temperatures of, for example, from 800 to 1100 degrees F. may be effectively maintained in the chamber 8. If these burners are forced in order to procure higher temperatures, the baffles will be burned out and efiicient operation is not possible.

The operation of furnaces ofthis general construction over the desired range of temperatures could be easily produced if it were possible to vary the Aarea of the spaces 7 1n accordance with results desired. This, however, cannot be effectively accomplished for several reasons well understood in the art. The present invention accomplishes, in effect, this same object by changing the effective areas of these spaces without any actual change therein, by varying the length of path of travel of the gases before they enter .the effective heating chamber', by varying the effective areas of radiation, and by varying the amount of heat delivered to the radiatingsurfaces from-the local combustion zones without necessitating any reduct1on in the minimum temperatures mentioned in these zones.

The operation will be clearly apparent by reference to the "upper set ,of burners in the 'llelflt handside of the furnace of Figure 1.

e burners may be assumed as bein at 12. These zones are closely adjacent t e roof, which constitutes a' heat radiating surface for the effective heating chamber 8, so that the gases have to travel only a short distance before reaching the roof. Due tothe capacity and location of the burners, and the area of the impinge on the roof 2 throughout such an angle that the area X is effectlve for radiating heat into the chamber 8. In actual oplocal temperature zone for each of these' spaces 7, these gases may;

eration, however, vas the local combustion zone for cach burner is not a point, a much greater roof area will be heated.

By reference to the lower set of burners shown on the right hand side of the furnace of Figure l and those of Figure 3, it will now be apparent Why they are capable of maintaining a lower uniform temperature in the chamber 8. These burners are each shown in Figure 1 as having a separate arch wall 13. As clearly shown in Figure 3, however, these arch be provided. The localgcombustion zones Lfor these burners are indicated'at 14 and 14', res ectively. These zones are removed from t e roof a greater distance so that the length of travelof the gases before reaching the roofis increased. This in itself, with a given minimum local vcombustion temperature, .is effective for keeping a lower temperature in the chamber 8, as they transmita smaller amount of heat to the roof. They also, in effect, provide a smaller radiating area, as with the arches 13 only the roof Within the area Y will radiate heat on each 4side of the furnace, while with the furnace shown in Figure 3, the area Z will be directly heated. In either case, the area is less than that heated by the upper set of burners, with the result that a lower temperature may be easily uniformly maintained in the chamber 8.

From the foregoing, it \will be apparent that -in producing high temperatures, it is only necessary to use the upper set of burners in such manner as to insure a maximum efficiency, by reason of the fact that the desired minimum temperatures in the local combustion zones ma be easily maintained Without any forced ring. For lower tem- Eeratures Within the effectiveheating chamer., the upper set of burners may be cut out of operation, and the lower set of burners, which are deeper down in the combustion chambers and more remote from the radiating surfaces of the roof, may be brought into operation. This construction is of material advantage in that it enables a single furnace to effectively take the place of two furnaces as heretofore required.

Still further advantages arise from the provision of a furnace of such construction that it may be easily used as a low temperature or a high temperature furnace without re uirin any alteration in the construction illereo and without decreasing its etliciency for either temperature.

1. In a furnace, a heating chamber, and a plurality of. burners for heating said chamber, said burners being so located that the respective paths of travel therefrom before entering the heating chamber are of different lengths, the heat from al1-of the burners on one side of the furnace entering walls need not alwaysr the heatingchamber through a common opening.

2. In a furnace, a heating chamber, side lwalls partly enclosing said heating chamber and defining an opening for heat to enter said chamber, and a plurality of burners located outside of said walls and so positioned that the paths of travel of the gases from different burners before entering the heating chamber are of different lengths, the heat from all of the burners on cach side of the furnace reaching the heating chamber through the opening on that side.

3. In a side fired furnace, a baffle defining a heating chamber and forming a combustion chamber, and a plurality of burners cooperating with said combustion chamber at different `points vertically thereof.

4. In a side fired furnace, baffles defining a heating chamber and forming combustion chambers laterally thereof, an upper set of burners communicating with each combustion chamber adjacent the top of its respective baffle, and a lower set of burners communicatingA with each combustion cham- Ioer adjacent the bottom thereof. l

5. In a side fired furnace, a side baflie providing on one side thereof a,heating chamber and on the opposite side a combustion chamber, an upper burner communicating with said combustion chamber adjacent the upper portion thereof for producing high temperatures within the heating chamber, and a second burner con'nnunicating with the combustion chamber adjacent the bottom thereof for producing lower temperatures Within the heating chamber. j

6. In a side fired furnace, a side bafiie providing on one side thereof a heating chamber and on the opposite side a combustion chamber, an upper burner communicating with said combustion chamber adjacent the upper portion thereof for producing high temperatures withinthe heating chamber, a second burner communicating with the combustion chamber adjacent the bottom thereof for producing lower temperatures within the heating` chamber, andan arch wall within the combustion chamber communicating with said second burner.

7. The method of operating heat treating furnaces, comprisingproviding .a passage of predetermined area for the transmission of heat from a heat source to the furnace proper where high temperatures are to be maintained, and varying the effective area of said passage between the heat source and I the furnace proper for the maintenance of lower temperatures.

8. The method of operating heat treating furnaces, comprising providing a passage of predetermined area for the transmission of heat where high temperatures are to be maintained, and varying the effective area cf said passage by changing the angle of heat radiation for the maintenance of lower temperatures.`

9. The method of operating furnaces over a wide temperature range, comprising producing a path oftravel of the heating gases from the heat source to the furnace proper of predetermined length for one furnace temperature, and varying the length of such path of travel of the gases for other temperatures.

10. The method of operating heat treating furnaces having a heat radiating surface, comprising varying the amount of heat delivered to the radiating surface from local combustion zones in which predetermined minimum local combustion temperatures are maintained'.

l11. The method of operating heat treating furnaces having a heat radiating surface, comprising delivering heat from .a given local combustion zone for the maintenancev of one temperature, and delivering heat from another local combustion `zone for the maintenance of a different temperature.

12. The method of operating heat treating furnaces having a heat radiating surface, comprising providing a passage of predetermined area forthe transmission of heat, and varying the effective area of said radiating surface without changing the area of said passage. I

13. The method of operating heat treating furnaces, comprising providing a luralty of local combustion zones at di erent effective distances from the heating chamber of the furnace, and successively utilizing different of said zones for the production of different temperatures within the heating chamber.

In testimony. whereof we have hereunto setour hand.

LANGFORD C. J ACOBUS. JOHN H. GILLOOLY.

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