US2171002A - Furnace - Google Patents

Description

N Aug. 29, 1939. c. H. LENGYEL FURNACE Filed March 1, 1939 Patented Aug. 29, 1939 UNITED" STATES PATENT OFFICE FURNACE Carl H. Lengyel, Kenmore, N. Y.

Application March 1, 1939, Serial No. 259,186

9 Claims.

This invention relates to furnaces and has particular reference to apparatus for affording a more efficient conversion of the chemical energy of fuel to heat by combustion.

The present invention may be said to have as its fundamental concept the substantial preheating of air before its deliverance to the point where the principal combustion of the furnace takes place, taken together with a more efl'icient in transfer of the heat of combustion for general use in heating. Procedure in accordance with the teaching of my invention is found to result in a far more complete combustion of the fuel and in a more rapid transfer of the heat of coml bustion to the air passing through the zone of combustion.

While multiple-stage heating may not, as a broad concept, be novel to the present invention, the manner in which the plural effect heating is 20 accomplished is not believed to be known in the prior art. Previous examples of step or multiple effect heating have depended upon the provision of multiple heating chambers and sometimes even on multiple fuel burners. In the present 25 invention the effect of step-heating is achieved without such complication of the apparatus and by utilizing the high heat conductivity of iron or a like material in a novel manner.

In the present invention the fire pot or com- 30 bustion chamber is so arranged that all of the incoming atmosphere is received through an annular conduit which has communication with the lower portion of the combustion chamber.

The actual combustion is preferably arranged to.

35 take place in the vicinity of the upper rim of such annular conduit where it communicates with 'the interior of the fire pot. This may be accomplished by disposing a number of fluid fuel burning jets directly above or immediately out- 40 side of the upper portion of the annular conduit and one convenient mode of arranging the apparatus of my invention is to so form the upper part of the annular conduit that it itself constitutes a burner comprising a circle of fuel burn- 45 ing jets leading from the upper face of the annular ring.

In proceeding according to my invention a special heat conducting and radiating element is provided for cooperation with the annular ,0 conduit, the fuel burner itself, and the walls of the combustion chamber. This element may be of a variety of forms but in one highly satisfactory embodiment of the apparatus of my invention a casing is provided which is similar in 55 conformation and nearly as large as the lower portion of the interior of the normal combustion chamber of the furnace. This casing is formed of a material which has a relatively high heat conductivity, cast iron being well suited to the requirements presented, and the casing has a 5- lower terminal portion which in effect extends downwardly into the annular conduit, having preferably a downwardly convex contour for achieving this result.

An exterior circular zone on the casing is. disl0 posed relatively close to the fuel burners whereby combustion takes place substantially against such zone and from this point upward the casing is spaced inwardly of the interior wall of the fire pot a relatively short distance whereby heat may readily be radiated from the diverging walls of the casing to the closely adjacent walls of the fire pot for transmission therethrough and exchange with a fluid, usually one that is being circulated around the outside of the fire pot.

The casing walls are of moderate thickness and the hollow interior of the casing is preferably filled with material having good heat insulating qualities, rock wool having been found highly satisfactory for the purposes of the present invention. It will be seen from this that heat imparted to the casing in the zone of combustion will be conducted rapidly along the wall of the casing and experiment shows that in an installation comparable in size and proportion to a usual domestic conversion burner installation the casing wall becomes cherry red within a relatively short period of time and over a considerable area, such area extending down to the very bottom of the casing where it is disposed within the annular conduit.

As a result of this heating of the casing walls to a relatively high temperature the incoming draft air, which enters upwardly through the annular conduit must of necessity come into close proximity to the highly heated surface of the lower portion of the casing wall and in fact the major portion of such draft will, by virtue of the arrangement of the parts of the apparatus, traverse a large portion' of the part of the casing wall which is disposed below the actual burners.

The result of the foregoing operation is that the draft air, upon its arrival at the burners, has already been brought to a relatively high temperature, as compared with the temperature of draft air in prior art devices of this type, and the gas, or carbureted fuel if such be used. is burning in an atmosphere which-is very much closer to its natural combustion temperature with a consequently more thorough, eflicient, and complete liberation, in the form of heat, of the chemical energy contained in the fuel.

A further improvement in efficiency is effected by the arrangement of the walls of the casing with respect to the walls of the fire pot or combustion chamber as these elements extend upwardly above the burners. The proximity of the casing. wall to the interior surface of the combustion chamber results in radiation of heat to the latter in a manner which will appear from a further consideration of the details of construction of the casing itself.

For disclosing a complete embodiment of my invention I have illustrated the principles thereof in connection with a furnace of a type widely employed domestically and having a conversion burner associated therewith. It is to be understood, however, that this embodiment is chosen merely by way of example and that such modifications as are dictated by varying conditions may be made without departing from the spirit or scope of the present invention as defined in the appended claims.

In the drawing:

Fig. 1 is a general side elevation of a. furnace with portions broken away to show the fire pot and combustion chamber thereof, which latter parts are illustrated in vertical cross section;

Fig. 2 is a fragmentary perspective view of one form of combined fuel burner and draft confining means in transverse cross section; and

Fig. 3 is a partial plan view of the combined burner and conduit ring of Fig. 2 with a portion of an inner casing member of my invention in horizontal cross section taken at about the upper level of the burner ring.

In the drawing like characters of reference denote like parts and the numeral II] designates a furnace casing having thereina fire pot and combustion chamber I I which may be of conventional sectional construction. Suitable means are provided for circulating air through the furnace I and about and in contact with the outside of the combustion chamber I I to heat the air for transmission to other points, usually to the room of a building to be heated. The novelty of the present invention, as it affects the construction of a furnace of the type being used as an example, is confined to the interior of the combustion chamber and the draft passage thereto and the remaining construction of the furnace proper may therefore be along conventional lines and will not be discussed in detail.

It will be noted that the combined fire pot and combustion chamber shown in the drawing has a lower annular portion which converges downwardly and an upper annular portion which converges upwardly, so that the combined device II has an enlarged medial portion and converging tapered portions extending both upwardly and downwardly therefrom. Where the furnace has originally been designed for use with solid fuel an ash pit will be disposed beneath the fire pot and combustion chamber II as at I2 and the ash pit also serves to convey draft air to the combustion chamber. In any event some source of air for supporting combustion will be provided at the lower side of the casing which houses the burner or other primary heat source.

In one means for accomplishing the results aimed at in my invention I provide an annular ring I3 which serves as an upward extension of the opening connecting the ash pit I2 or other draft source with the fire pot or combustion chamber II. The burning means are to be arranged in intimate association with the upper terminus of the ring I3 and for convenience of manufacture the upper end of the ring I3 may itself be formed to constitute a ring of jets for the combustion of fluid fuel.

As appears from a consideration of Figs. 1 and 2 of the drawing, the ring I3 has a circular conduit I4 formed at its upper inner side and at one point the conduit I4 has a downward extension I5 for communication with a source of fluid fuel. Merely by way of example I have shown the apparatus of my invention as arranged to utilize fuel gas but liquid fuel in the form of oil may be employed by making suitable modifications in the equipment and its arrangement.

A plurality of burners II are arranged about the ring I3 and these burners may constitute tubes which extend vertically completely through the conduit and are open at both their upper and lower ends. Suitable openings I8 are formed in the tubes at points located within the interior of the conduit I4 for the purpose of admitting fuel gas to the individual tubes. The upper ends of the tubes constitute gas jets and the openings at the lower ends of the tubes serve to admit air to the tubes for mixture with the gas in the manner which is usual in burners operating according to the Bunsen principle.

Fuel gas is piped to the ring I3 by any suitable piping 20 and enters the conduit I4 by way of the downward extension I5 thereof. While automatic control of the operation of the furnace is not necessary to operation of my invention, I have shown schematically a casing 2i which is interposed in the piping 20 and. contains a thermostatically controlled valve. The operation of such valve is also usually arranged to control admission of draft air to the furnace so that the furnace will not become cooled by convection currents therethrough after the burners have been turned off by operation of the automatic control valve. Such means are indicated in Fig. 1 where a casing 23 which communicates with the combustion chamber through the ash pit I2 is provided with a valve 24 which operates with the gas control valve through a mechanical connection 25.

A pilot light 28 may be provided and in the i1- lustrated instance the pilot light is fed through a conduit 29 which communicates with the piping 20 beyond the automatic valve mechanism so that it is in constant communication with the gas supply unless it is manually turned off by means of a valve 30. To supply oxygen for operation of the pilot 28 a small vent 3| is provided in the wall of the casing 23. Of course many forms of protective devices for both the pilot light and the feeding of fuel to the burners may be employed in conjunction with the apparatus of my invention without affecting the novel mode ofoperation proposed herein.

I shall now describe an element which is disposed within the combustion chamber and is of such conformation and is so positioned as to affect the fluid current through the furnace both prior to and after its passage past the burners. The shape and arrangement of the element referred to here will vary with variations in the arrangement of the combustion chamber and the burners of furnaces to which my invention is to be applied but in furnaces which have the conventional fire pot and combustion chamber and are of the type illustrated in the drawing herein, the element may take the form of a substantially ellipsoidal casing member.

In the specific example of the drawing I have U6. SYQVES & FURNACES,

shown complementary upper and lower casing portions 33 and 34 respectively which comprise relatively thin cast iron walls and form a closed ellipsoidal casing and for more flexible and efficient operation I preferably fill the interior space thereof with a good insulating material which may be rock wool, or the like, and is designated 35 in the drawing. The relatively thin heat conducting casing wall and the fact that the large space inside the casing is not heat absorbent minimizes the amount of heat that might under other conditions pass off at the top of the casing into the flue and be wasted. The casing 33, 34 may be supported in its illustrated position by projections 36 formed integrally with the burner ring l4 or in any other convenient manner and its position is such that a relatively narrow annular passage is provided between the upper inside edge of the ring 14 and the adjacent surface of the lower casing portion 34.

It will be noted that with the casing in this position the lower convex or 'ovoid portion of the casing portion 34 projects downwardly into the space enclosed within the ring l3 and in such manner as to present an upwardly diverging more or less conical wall leading to the region of the burners H. Progressing upwardly beyond the burners I1 the wall of the casing approaches a position of relatively close proximity to the inner Wall of the fire pot or combustion chamber I l and continues in such condition of proximity to a point substantially above the largest lateral dimension of the combustion chamber.

It is particularly to be noted that the ring l3 fits closely over the opening between the combustion chamber H and the lower draft chamber or ash pit l2 and that as a consequence no air is permitted to enter the combustion chamber ll save through the central opening in the ring l3. When the furnace is put into operation by supplying gas to the burners l1, the burners heat the casing 33, 34 to a red heat and owing to the high heat conductivity of the casing, the heat is conducted over a substantial area of the casing both upwardly and downwardly of the burners II. In fact, the high degree of heat imparted to the casing 33, 34 in this manner carries down along the converging lower portion of the casing element 34 to its very bottom.

It will be seen from the foregoing that air coming to the combustion chamber from the draft passage l2 comes into contact with this highly heated lower portion of the casing element 34 before it arrives at the burners H, as shown by the arrows in Fig. 1, and is so brought to a relatively high temperature before reaching the vicinity of the burners. With the surrounding atmosphere in such a heated state the gas issuing from the burners l l is very much closer to its natural ignition temperature and a much more thorough and efficient combustion thereof takes place than in prior art practices.

The burners are so arranged that they play directly against the adjacent casing wall and the casing wall above the burners I1 is so arranged that whatever heat is not conducted to the bottom of the casing for preheating draft air is radiated from the casing wall to the closely adjacent wall of the combustion chamber. While the contour of the upper casing portion 33 has been illustrated as forming a continuation of the relatively narrow annular space between the casing and the inner surface of the wall of the combustion chamber l I, this is not necessary to satisfactory operation. When the walls of the combustion chamber ll begin to converge upwardly, the natural convection current of the heated air is upward against the wall of the chamber, whether or not the influence of the upper casing portion 33 is present.

Access may be had to the interior of the combustion chamber H by means of the door 38 and in order that the pilot light 28 may be rendered accessible for lighting and inspection, the casing 33, 34 is shown flattened in the vicinity of the door 38 as at 39.

The efficiency of heat transfer in the furnace of the present invention is evidenced in actual installations by the coolness of the stack leading from the furnace and the all-around efficiency of combustion and heat transfer is proved by the relative economy of operation as compared with comparable furnaces of other types using the same fuel.

I claim:

1. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit leading upwardly from a source of draft to communicate with said opening, a plurality of bumers spaced about and closely adjacent the upper end of said conduit, and a pre-heating element comprising a casing of heat conducting material having a downwardly convex portion disposed over and in close proximity to said burners whereby its more central portions are disposed below said burners and substantially within said conduit whereby to be contacted by incoming draft 2. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit leading upwardly from a source of draft to communicate with said opening, a plurality of burners spaced about and closely adjacent the upper end of said conduit, and a body of heat insulating material having a casing of heat conducting material, said casing having a downwardly convex portion disposed with portions thereof in close proximity to said burners and with its more central portions disposed substantially within said conduit.

3. In a furnace having a combustion chamber and an opening at the bottom thereof for communication with a source of draft, an annular conduit leading upwardly from said opening, a plurality of burners arranged concentrically with respect to said conduit and adjacent the upper end thereof, and a body of heat insulating material having a casing of heat conducting material, said casing having a downwardly convex portion disposed in close proximity to said burners and substantially concentric therewith whereby its more central portions project downwardly into said conduit element.

4. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit leading upwardly from a source of draft to communicate with said opening, a plurality of burners spaced about and closely adjacent the upper end of said conduit, and means for diverting air for flow through said conduit and said combustion chamber in a predetermined manner, said means being disposed in said combustion chamber and comprising a casing shaped similarly to the combustion chamber but smaller than said combustion chamber whereby to form therewith a relatively narrow annular air passage upwardly from said burners, the lower portion of said casing comprising a downwardly convex portion disposed in close proximity to said burners and with its more central portions disposed substantially within said conduit.

in ROW 5. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit; leading upwardly from a source of draft to communicate with said opening, a plurality of burners spaced about and closely adjacent the upper end of said conduit, and means for diverting air for flow through said conduit and said combustion chamber in a predetermined manner, said means comprising a casing disposed in said combustion chamber and shaped similarly to the combustion chamber but smaller than said combustion chamber to form therewith a relatively narrow annular air passage upwardly from said burners, the lower portion of said casing comprising a downwardly converging portion disposed in close proximity to said burners and projecting downwardly therefrom into said conduit whereby air passing upwardly through said conduit contacts the surface of said lower casing portion and is diverted outwardly and upwardly therealong to be heated thereby before it reaches said burners.

6. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit leading upwardly from a source of draft to communicate with said opening, a plurailty of burners spaced about and closely adjacent the upper end of said conduit, and pre-heating means comprising an element of heat conducting material having downwardly converging walls disposed in close proximity to said burners and projecting downwardly therefrom into said conduit whereby air passing upwardly through said conduit contacts the surface of said lower casing portion and is diverted outwardly and upwardly therealong to be heated thereby before it reaches said burners.

7. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit in communication with said opening and leading upwardly from a source of draft, a plurality of burners spaced about and closely adjacent the upper end of said conduit, and means in said combustion chamber for diverting air for flow through said conduit and said combustion chamber in a predetermined manner, said means comprising a body of heat insulating material having a relatively thin heat conducting casing,

said casing being shaped similarly to the combustion chamber but smaller than said combustion chamber whereby to form therewith a rela-.

tively narrow annular air passage extending upwardly from said burners, the lower portion of said casing comprising a downwardly convex portion disposed in close proximity to said burners and with its more central portions disposed below said burners and substantially within said conduit.

8. In a furnace having a combustion chamber and an opening at the bottom thereof, a conduit in communication with said opening and leading upwardly from a source of draft, a plurality of burners spaced about and closely adjacent the upper end of said conduit, and means in said combustion chamber for diverting air for flow through said conduit and said combustion chamber in a predetermined manner, said means comprising a body of heat insulating material having a relatively thin heat conducting casing, said casing being shaped similarly to the combustion chamber but smaller than said combustion chamber whereby to form therewith a relatively narrow annular air passage extending upwardly from said burners, the lower portion of said casing comprising a downwardly converging portion disposed in close proximity to said burners and projecting downwardly therefrom into said conduit whereby air passing upwardly through said conduit contacts the surface of said lower casing portion and is diverted outwardly and upwardly therealong to be heated thereby before it reaches said burners.

9. In a furnace havinga combustion chamber and an opening at the bottom thereof, a conduit leading upwardly from a source of draft to communicate with said opening, a burner ring disposed about and closely adjacent the upper end of said conduit, and a pre-heating element comprising a casing of heat conducting material having a downwardly convex portion disposed over and in close proximity to said burner ring whereby its more central portions are disposed below said burner ring and substantially within said conduit whereby to be contacted by incoming draft air.

CARL H. LENGYEL.

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