US1913170A - Apparatus for heating - Google Patents

Description

J1me w. N. MCCUTCHEON ET AL 1,913,170

APPARATUS FOR HEATING Filed Dec. 12, 1930 3 Sheets-Sheet 1 guvsmo kw-n m M rm June 6, 1933. w. N. MCCUTCHEON ET AL 0 APPARATUS FOR HEATING Filed Dec. 12, .1930 5 Sheets-Sheet 2 I; a! I Jun 6, 1933.

' W. N. M CUTCHEON B AL APPARATUS FOR HEATING Filed Dec, 12, 1950 3 Sheets-She'et 3 INVENTORS Patented June 6, 1933 UNITED STATES PATENT orrlcs WILLIAI 1i. IOOUTGHMN, OI TEOBNBUBG, AND ARCH V BI'I'TB, F ALLISON rm, PENNSYLVANIA AP'PABATUB FOR HEATING Application filed December 18, 1830. Serial 1T0. 501321.

The present invention relates broadly to the art of combustion, and more articularly to an apparatus for controlling t e su ply, mixing and burning of a combustible ingredient and a combustion supporting ingredient.

For urposes of facilitating a description and understanding of the present invention it will be described in connection with the burning of as as the combustible ingredient, but it will understood that the .utility of the invention is not limited with respect to the characteristic of these two types of combustion, yellow flame combustion may be considered as the characteristic flame resulting from a mixture of air and gas beginning at the mouth of the burner, without any previous air or air pro-mixing. Blue flame combustion, on the contra is usually considered as the characteristic ame resulting from a pre-mixing of the air required, or a large part of the air, and the gas, in advance of the mouth of the burner, and the admission of the pre-mixed gases to the combustion chamber or furnace chamber.

From a practical standpoint blue flame combustion is so employed that it is usually characterized by a localized zone of intense temperature. We have found, on the contrary, that yellow flame combustion, or luminous flame combustion as it is sometimes called, may be so employed as to involve substantially uniform heating over a very substantial area. It is also true, of the present invention that the effective flame temperature with yellow flame combustion may be lower than the corresponding effective flame temperature with blue flame combustion.

In heating furnaces, such for example as annealing-ornormalizing furnaces, it is customaay to utilize a blue flame, and rovide such ames at distances which are su ciently close to enable the obtaining of the desired temperature condition. This necessarily results in a' heating or heat treating zone having non-uniform' temperatures in different portions of the chamber.

It is one of the objects of the present invention to provide an improved apparatus for use under such or similar conditions 5 whereby a more nearly uniform temperature condition throughout the entire chamber can be obtained with lower localized temperatures.

It is also customary in the art to provide 60 chambers of the general character referred to of the so-called muflle, semimuflled or baflle type. With such structures radiation from the baflle or muflles constitutes one of the principal sources of heat, and it is therefore 0 customary to burn the fuel under such conditions that there is a very appreciable temperature diiference on opposite sides of such aflies or muflles.

The present invention contemplates a zone into which the combustible ingredient and the combustion supporting ingredient are delivered and within which partial combustion only takes place. It is one of the objects of the invention, however, to deliver such ingredients under such controlled velocity and pressure conditions, and in such amounts with respect to the dimensions of the zone as not to obtain such a pronounced difference in temperature conditions between such zone and the main portion of the chamber. Thus, while it has not heretofore been unusual to have a. temperature difference between the combustion chamber in back of the mufile or baflle and points within the furnace chamber proper of from 600 to 800 F., the present invention will usually involve a temperature difference of not appreciably over 200 F. and usually less.

From the foregoing, it will be apparent to so those skilled in the art that the'present invention involves burning of fuel and air under accurately controlled conditions, with delivery of the fuel and, air under predetermined velocity and pressure conditions, and 05 properly vcorrelating these factors to the physical dimensions of the parts depended upon for forming the partial combustion zone before referred to.

In the accompanying drawings there are illustrated more or less diagrammatically, certain preferred embodiments of our inv tion. In'the drawings: I

Figure 1' is a transverse sectional view through one form of furnace constructed in accordance with the present invention;

Figure 2 is a longitudinal sectional view along the line II-II of Figure 1 illustrating one arrangement of within the furnace;

Figures 3 and 4 are detail sectional views illustrating different embodiments of the mvention; and

Figu

a plurality of burners re 5 is a view similar to Figures 3 and 4 illustrating still another formof the invention.

. Referring generally to Figures 1 and 2 of the drawings, we have illustratedafurnace comprising a roof 2, side walls 3 and a hearth 4, these parts hereinafter being generically referred to in the claims as confining walls regardless of their location or direction of.

- rather extreme cross sectional area and receives air from the manifold 5 through a re-' stricted orifice or controlling valve 10 by means of which an appreciable pressure reduction may be obtained within the air conduit as distinguished from the pressure within the manifold. In like manner, the gas conduit may receive its supply of gas through a regulating restriction in t e form of a valve 'or orifice plate 11.

In the form of the invention illustrated in Figures 1 and 2 the various air conduits and the various gas conduits in any given zone transversely of the furnace are all connected to common manifolds for air and gas respectively, these manifolds in turn receiving air and gas from any desired source, not shown.

' By making these manifolds of fairly large cross sectional area it is possible to maintain a suficient volume of air and gas therein to satisfactorily feed any desired number of gas and air conduits without obtaining any appreciable pressure drop in the manifolds by reason of the quantities withdrawn therefrom by the individual conduits, and thus maintain a substantially constant pressure differential across the valve or orifice plates provided intermediate the conduits and the manifolds. i y

In both of these figures, also, the conduits are illustrated as effective for delivering their respective ingredients into a zone 12 at closely ad acent lpoints. These points of discharge are both lustratcd in these figures as being below a cover member 14 which extends in substantial parallelism to the adjacent wall,

- which is here the hearth 4, and which is s aced from the openings in the direction of burg of the ingredients therefrom. The cover p to thus forms a definite zone intermediate the conduits themselves and the main heatmg chamber 15. If the ingredients were delivered into such a zone under pressure conditions too high relative to the zone dimenslonsltlvo undesirable conditions mi result. of these would be an agitation of such nature as to produce a relatively complete mixing and therefore substantially complete combustion within 7 the zone itself, and the other would be to obtain a directional flow such as to prevent partial combustion within the zone and obtain primary combustion directly within the chamber 15. In accordance wlth the present invention neither of these conditions is desired. We therefore construct the cover member of such total area with respect to, its distance from the points of disc arge and the area and velocity characteristics of such points that there will only be a partial combustion within the zone 12.

We havepbserved that with a construction of the character described, after it has been in operation for a short time, the cover'member reaches such a temperature as to apparently be eifective for breaking down the fuel and assisting in further combustion which is carried on outside of the zone and directly within the heating chamber itself. It is our belief that this heating of the cover member is due principally to temperature conditions within the furnace chamber rather than the partial combustion within the zone below the cover member.

By providin a lurality of such burner units within a '0 am r, it is possible to maintain a relatively uniform temperature throughout the entire chamber, and a combustion condition which is characterized by appreciable luminosity throughout, and almost complete absence of anything resembling localized high temperature zones. It will be apparent that the delivery of ingredients may be such that the combustion is of the yellowflame type, the visible conditions within a furnace giving evidence of the fact that fine carbon particles are maintained in suspension throughout the chamber insuch manner as to at least assist in the luminous condition referred to.

For purposes of illustrating by way of example only, one specific embodiment which ght has been found to satisfactorily give the result desired, and for the purpose of afiording a better understanding of how the invention may be concretely embodied, reference will be made to a typical installation. Such an installation comprised a heating chamber having an over-all len h of 8 ft. a width of 4 ft. and an average eight of 3 ft. Such chamber was provided with five burners of the metal construction heretofore described, the urners being s aced on approximately 18 inch centers. ith this construction it will be apparent that the heating chamber of .the furnace contained approximately 96 cu. ft., thus making each burner responsible for the heating of a volume of approximately 19 cu. ft. Each of the'cover members may be i 10 of any desired configuration, but they are.

conveniently formed either of substantially square or substantially circular tile or other suitable material;

In the construction referred to, each tile had an area of approximately 256 sq. inches, and they were each spaced from the adjacent wall 4 at a distance of 2 in. Each cover member thus provided a pro-mixing and partial combustion zone having a volume of approximately 640 cu. in. Into each zone there was discharged a volume of fuel varying from 80 cu. ft.-to 240 cu. ft. per hour. This discharge of gas was efi'ected with a pressure in the gas manifold varying from 1n. to

.6 in. of water through a gas conduit having an effective area of .533 sq. in. with an orifice of 19/64 of an inch. The air, on the other hand, varied with the fuel from a minimum of 700 cu. ft. to a maximum of 2400 cu. ft. per minute. 'This-discharge of air was obtained with a manifold ressure varying from 1- in. to 8 in. of water t rough a conduit having an effective cross sectional area of 3.96 in. and containing a 1 1n. orifice. This will serve to illustrate a preferred embodiment of the present invention.

The results of the structure described, and 1 the relationship of the-parts, was such that the fuel and air were so delivered as to give partial combustion only within each zone, the principal combustion being contlnued entirely exteriorly of each zone and directly within the heating chamber. As before pointed out, it is our belief that the partial combustion within the relatively confined zonesaided by contact of raw or unmixed gas with the heated surfaces of the cover members produces a partial breaking up or breaking down of the hydrocarbon-content the entire chamber itself, however, being approximately uniform and being visually devoid of any indication of extremely high temperature Zones or non-uniform heating conditions.

In Figure 3 there is'illustrated a slightly modified embodiment of .the invention in which parts corresponding to the parts already described are designated by the same reference characters as those heretofore used, but having a prime afiixed thereto. In this embodiment the gas conduit 9' is illustrated as extended upwardly to a point intermediate the wall 4 and the cover member 14' and provided with a flange 16. Such an arrangement is effective for maintaining a better separation between the two ingredients until their actual delivery into the zone 12', thus precluding pre-mixing with any resultant tendency toward a blue flame condition,

should this be desirable.

In Figure 4, the cover member 17 is illustrated as carried adjacent one edge by a pier or support 18 having therein a fuel discharge port 19 and an air discharge port 20. In this embodiment the cover member while spaced from the adjacent wall of the heating chamber, lies in a direction generally parallel not only to such wall, but to the direction "of discharge of the fuel and air. The relative pressure, velocity and area conditions, however, are such that a condition similar to that before described is effectively maintained.

In Figure 5 of the drawings there is illustrated a slightly modified embodiment of the invention in which the gas conduit 21 is adjust-able Within the air conduit 22 to thereby change the point of contact or initial mixing of the air and gas. With the gas conduit discharging into the air conduit at a'point below the plane of the hearth23. we have found that the cover member 24 may be moved closer to the hearth, as indicated in Figure 5; Such a -construction gives a smaller discharge area from the zone beneath the cover member and a higher discharge velocity. The dischargevelocitv is such that the principal combustion within the furnace is efl'ectively distributed throughout an appreciable area thereof.

All of the forms of our invention are characterized by one or more partial combustion.

combustion is obtained, but regardless of thetvpe of combustion, the structure and operation are such that there is only partial combustion within the zones themselves with the principal combustion exteriorly of such zones. The type of combustion used will be Ill determined to a large extent, at least, by the temperature and atmosphere conditions desired, the yellow flame type being usually preferable where conditions permit its use.

While wehave herein described and illustrated certain preferred embodiments of our 5 invention, it will be understood that changes in the construction, relationship and arrangement of the parts may be made without departing either from the spirit of our invention or the scope of our broader claims.

We claim:

1. In a furnace, refractory bottom and side walls, a burner port in one of said walls, a refractory cover member spaced from the wall and extending parallel thereto, over- A lying the port and extending therebeyond,

and individual conduits extending into said port for supplying air and fuel under pressure for combustion in the furnace. 7

2. In a furnace, refractory bottom and side walls, a burner port in one of said walls, a refractory cover member spaced from the wall and extending parallel thereto, overlying the port and extending therebeyond, and individual conduits extending into said port for supplying air and fuel under pressure for combustion in the furnace, one of the conduits projecting beyond the port and having a flange between the cover member and the hearth. 3. In a furnace, refractory bottom and side walls, a burner port in one of said walls, .a refractory cover member spaced from the wall and extending parallel thereto, ove'rlying the port and extending therebeyond, and individual conduits extending into said port for supplying air and fuel under .pressure for combustion in the furnace, one of the conduits having an adjustable portion whereby the oint of initial mixture of air 40 and gas may e changed. 7

4. In a furnace, refractory bottom and side walls, a plurality of burner ports in said Walls, refractory cover members spaced 4 from the walls and extending parallel there- 5 to, overlying the ports and extending therebeyond, individual conduits extending into said ports for supplying air and fuel under pressure for combustion in the furnace, and fuel and air mains having connections with the conduits of all said ports.

In testimony whereof we havehereunto set our hands. 1

WILLIAM N. MOGUTCHEON.

ARCH V. RITTS.

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