US2502947A - Heating - Google Patents

Description

F. O. HESS April 4, 1950 l 1E ATING Filed Feb. 25, 1946 2 Sheets-Sheet 1 Patented Apr. 4, 1950 HEATING Frederic 0. Hess, Philadelphia, Pa., assignor to Selas Corporation of America, Philadelphia, Pa., a corporation of Pennsylvania Application February 23, 1946, Serial No. 649,677

3 Claims.

My invention relates to heating, and it is an object to provide an improvement for heating a medium with the aid of a gas burner having a substantially closed combustion space in which practically complete combustion of a combustible gaseous mixture is accomplished and from which heated products of combustion are discharged through a restricted outlet in the form of a heated gas stream, the heating of the medium being effected in such a manner that it mixes with and is entrained in the heated products of combustion forming the gas stream.

It has already been proposed to employ burners having a combustion space provided with an inlet at one end for a combustible gaseous mixture and an outlet at its opposite end for discharging heated products of combustion. In such burner the combustion space has its inner wall surface and restricted outlet formed of high temperature refractory material so that combustion of the gaseous mixture may be accomplished therein and heat the inner wall surface to incandescence and produce a region of intense heat in which substantially complete combustion is accomplished. The products of combustion developed in the combustion space are discharged therefrom through the outlet at a temperature 'nearly equal to the temperature in the combustion space. V

In accordance with the present invention a gas burner of the character just described is advantageously utilized to effect heating of a medium other than the combustible gaseous mixture and cause mixing and entrainment of such medium in the heated products of combustion which are discharged from the burner in the form of a high velocity heated gas stream. The composition of the medium supplied to the burner to be heated therein and entrained in the heated products of combustion may vary and assume a variety of forms. Not only is the gas burner effectively employed as a heating tool to heat the medium introduced therein, but a high velocity movement is imparted thereto due to entrainment of the medium in the heated products of combustion discharged through the burner outlet at an exceedingly high velocity.

In many instances it is desirable to mix a gaseous medium, such as steam, for example, with the heated products of combustion produced by the burner. This is especially true, for example, in those heating applications where the presence of steam or moisture promotes and facilitates processing of material being heated and against which the gas stream impinges. Also, the medium supplied to the burner to be heated therein may consist of a hydrocarbon fluid which previously has been preheated and which requires additional heating to effect cracking thereof. In such cases the cracked hydrocarbon fluid co- 2 mingles with and is discharged from the burner along with the heated products of combustion. Further, the medium to be heated in the burner may comprise comminuted or granular material which requires heating thereof to an elevated temperature to promote and facilitate the use of such material in a particular heating application. For example, in the manufacture of certain products, such as asbestos shingles or artificial bricks, it may be desirable to provide a coating for such products which simulates a natural slate or brick color. When the surfaces of such products are impregnated or coated with asphalt or the like, a suitable granular or comminuted material may be fed to the burner to effect sufficient heatingv thereof and cause such heated material entrained in the high velocity gas stream to be forceably driven into the surfaces of the articles coated or impregnated with asphalt, whereby such heated particles lodge and become firmly bonded in the surfaces. Also, heating of comminuted o-r granular material containing Water of crystallization may be effected in the burner to cause such material to expand many fold, so that a given volume of such heated material will weigh considerably less than the raw material prior to being heated.

The above and other objects and advantages of the invention will be more fully understood upon reference to the following description and accompanying drawings forming a part of this specification, and of which Fig. 1 is a view more or less diagrammatically illustrating heating apparatus for practicing the invention, the gas burner of which is shown in section and taken on line l! of 2; Fig. 2 is a horizontal sectional view, taken on line 2-2 of Fig. 1, to illustrate details of the burner; Figs. 3 and 4 are vertical sectional views of other forms of burners generally like that of Figs. 1 and 2 for practicing the invention; and Fig. 5 is a fragmentary horizontal sectional view, taken on line 5-5 of Fig. 4, to illustrate the burner more clearly.

Referring to Figs. 1 and 2, one form of gas burner for practicing the invention includes a base member I l' shaped to form a plurality of inlet chambers l2 and Hi. The centrally disposed inlet chamber H is provided with a threaded inlet [5 which receives a conduit it; through which a combustible gaseous mixture is delivered from a suitable source of supply.

The inlet chambers I4 at each side of the central inlet chamber l2 are provided with threaded inlets H which receive conduits I 8 through which a gaseous medium is delivered from a suitable source of supply, as will be explained more fully hereinafter. In one of the conduits I8 is provided a manually operable valve l9 for controlling the pressure and rate at which the gaseous medium is supplied to the burner II). It is to be understood that a similar manually operable valve may be provided in the other conduit I3. The base member H is formed with internal shoulders 23 at the upper part of the inlet chamber l2 to receive an apertured member or burner screen 2| formed with a plurality of small passages 22. As shown in Fig. 2, the burner screen 2| comprises two spaced apart pairs of relatively thick plates notched to form cylindrical-shaped apertures through which extend hollow tubular members 23 and 24, and a plurality of relatively thin plates each having one face thereof formed with a plurality of slots of relatively small depth. The plates are stacked and closely held together with a slotted face of each thin plate, except one end plate, contiguous to and contacting the smooth face of an adjacent plate so as to form the small passages 22 and also the apertures for the tubular members 23 and 24.

To the top surface of the base member II is secured a slotted clamping plate 25, as by screws 25, for example, which overlies flanges or lugs 21 formed at opposing sides of the burner screen 2|. The clamping plate 25 is also formed with two rows of openings 28 each of which is directly above the top reduced portions of the inlet chambers 4. In order to obtain a gas-tight seal about the burner screen 2| and the openings 28, a gasket 23 formed of suitable material, such as asbestos, for example, is interposed between the plate 25 and the base member l. The spaces 30 above the lugs 21 maybe filled with a suitable high temperature fire-brick cement. The large open end of a cup-shaped metal shell or casing 3| is removably secured at 32 to the base member l Within the outer shell 3| is provided an outer wall or lining of refractory material. The outer refractory lining is formed by a hollow rectangular shell comprising two complementary wall parts, U-shaped in horizontal section, and having parallel ends 33. The extreme vertical Z-shaped edges of opposing ends 33 at each end of the bumer III are in abutting relation, as indicated at 34' in Fig. 2.

As best shown in Fig. 2, the outer surfaces of the sides 34 of the outer refractory lining conform to the shape of the metal shell 3|. The ends 33 of the outer refractory wall parts are straight throughout the heights of these walls while the connecting side walls 34 include straight wall portions extending upwardly from the clamping plate 25 to an intermediate part of the outer refractory lining, and inwardly sloping wall portions which terminate in a narrow rectangular-shaped slot or discharge port 35 extending or projecting through an opening at the top part of the metal shell 3|.

A second inner refractory lining is disposed within the outer refractory lining just described and forms a combustion chamber 38. The inner refractory lining is also formed by a hollow rectangular shell comprising two complementary parts, U-shaped in horizontal section, and having parallel ends 31 over which snugly fit the ends 33 of the outer refractory wall parts. The extreme vertical Z-shaped edges of opposing ends 3] at each end of the burner III are in abutting relation, as indicated at 38 in Fig. 2.

The ends 31 of the inner refractory wall parts are straight throughout the heights of these walls while the connecting side walls 33'include straight wall portions extending upwardly from the plate 25 substantially the same distance as the straight wall portions of the outer refractory lining, and inwardly sloping wall portions terminating in a 4 narrow rectangular-shaped slot or'restricted out let 43 closely adjacent to the discharge port 35.

The bottom edges of the inner refractory lining overlie and lit snugly against the peripheral edges of the narrow portion of the burner screen 2| extending through the slot in clamping plate 25 toward the outlet 40. The side walls 39 of the inner refractory lining are rigidly held in position against the upper part of the burner screen 2| by vertically extending ribs 4| formed at the inner surfaces of the side walls 39 of the outer refractory wall parts.

The ribs 4| extend vertically upward from the .clamping plate 25 to a region adjacent to the outlet 48 formed by the inner refractory lining, and spaces 42 between adjacent spaced apart ribs 4| form vertically extending passages which communicate at their lower ends with the openings 28 in the clamping plate 25. When the cupshaped shell 3| is secured to the base member [I at 32, both the outer and inner refractory linings are rigidly held in position, the bottom parts of the ribs 4| bearing against the inner refractory lining to cause the latter to fit snugly against the upper narrow part of the burner screen 2| while the top sloping parts of the ribs exert a downward component of force against the upper part of the inner refractory lining so that the latter will be firmly held and seated against clamping plate 25.

The hollow tubular members 23 and 24, which pass through the apertures in the burner screen 2| extend longitudinally of the combustion space 35 from the inlet end thereof toward the restricted outlet 40. Each of the hollow members 23 and 24 passes through an opening in the bottom part of the inlet chamber l2 which threadedly receives a bushing 44, suitable packing material 45 also being provided to form gas-tight connections at the regions the hollow members 23 and 24 extend exteriorly of the burner.

The hollow member 23 is connected to a conduit 46 in which is provided a manually operable valve' 41 and through which a gaseous medium may be supplied under pressure from a suitable source of supply, as will be described presently. The hollow member 24 is arranged to receive a comminuted or subdivided material from a suitable source of supply. As diagrammatically illustrated in Fig. 1, the apparatus for supplying the comminuted or subdivided material to the hollow member 24 may include a conduit 48 which is connected at one end to the lower end of hollow member 24 and at its opposite end to the outlet of a suitable air blower 49 arranged to be driven in any suitable manner (not shown). A hopper 58 adapted to hold a body of comminuted or subdivided material is fixed at its narrow open end to' an opening formed in the conduit 48. An adjustable damper 5| may be provided in the conduit 48 between the hopper 50 and the outlet end of the blower 49 to control the rate at which air is discharged from the blower. for flow through the conduit. A rotatable agitator 52, which is driven in any suitable manner, may be provided in the narrow bottom part of the hopper 50 to insure a uniform rate of flow of the comminuted or subdivided material from the hopper into the conduit 48..

Io operate the burner In to produce a high velocity gas stream of heated products of combustion, a combustible fuel mixture comprising a gaseous fuel and a combustion supporting gas is supplied through conduit Hi from a suitable source of supply. When the burner I0 is relatively cool and at a low temperature, the gaseous mixture supplied thereto passes through the inlet chamber l2, burner screen 2|, and chamber 36 from which it is successively discharged through the outlet 40 and discharge port 35. The combustible gaseous mixture is initially supplied to the burner to at a relatively low pressure which maybe equivalent to 5 or 6 inches of water column, for example, so that the gaseous mixture disare produced and maintained at the upper ends a.

of the small openings 22.

When the flames are being maintained within chamber 36 at the top surface of the burner screen M, the pressure of the gaseous mixture supplied to the burner l0 may be increased. After a short interval of time, the flames maintained at the top surface of the burner screen 2| effect such heating of the inner refractory lining that these surfaces are heated to a highly incandescent condition. The heating of the inner refractory lining to an incandescent temperature and radiant heat therefrom promotes substantially complete combustion of the gaseous mixture in chamber 36 before the mixture reaches the restricted outlet 46. From the outlet 40 is discharged a high velocity jet or stream of heated gases consisting substantially entirely of the heated products of combustion.

During normal operation the burner i 0 is char acterized by the absence of a bright and luminous flame. It is only when the burner I0 is first started that a flame is momentarily maintained at the elongated slot or discharge port 35, as previously explained. After the gaseous mixture has once been ignited, the delivery pressure of the gaseous mixture is reduced sufliciently to cause backflring into the chamber 36, so that burning of the gaseous mixture will take place at the top surface of the burnerscreen M.

In a burner of the type just described, the heated products of combustion are discharged from the combustion chamber 36 through the restricted outlet 40 thereof at an elevated temperature ranging from 2700" F. to 2900 F. and higher when a combustible gaseous mixture of air and ordinary gas, such as city gas, for example, is supplied at a pressure in the neighborhood of three pounds per square inch. Under such operating conditions, the pressure in the combustion chamber 36 may be equivalent to from 55 to 70 inches of water column and appreciably above that of atmospheric pressure.

In accordance with the present invention the gas burner I0 is advantageously utilized to effect heating of a medium which may be in a solid or gaseous or vaporous state. In the burner In just described provision is made for separately or simultaneously heating a vaporous fluid and comminuted or subdivided material in the combustion space 36.

During operation of the burner I0, a suitable gaseous medium may be supplied under pressure from a source of supply through the conduit 46 to hollow member 23. The gaseous medium is discharged from the hollow member 23 into the combustion space 36 in which heating thereof is effected. Due to the high heating temperatures maintained in combustion space 36, the gaseous medium is rapidly heated therein and mixes with the heatedproducts of combustion. The heated gaseous medium is entrained in the heated products of combustion discharged from the combustion space 36 through the restricted outlet 40 in the form of a high velocity gas stream.

Different gases or vaporous media may be supplied to the hollow member 23 depending upon the end results desired. For example, the processing of many materials is facilitated and promoted when a gaseous medium, such as steam, for example, is supplied to the combustion space for admixture to the heated products of combustion. Thus, in particular heating applications the presence of steam in the heated products of combustion, which may be superheated in the combustion space 36, may impart desired physical properties to material against which the gas stream impinges. Also, the gaseous medium supplied to the combustion space may be a hydrocarbon fuel which previously has been heated and which is heated to a higher temperature in the burner to effect cracking thereof. In each instance the pressure and rate at which the gaseous medium is supplied to the combustion space 35 can be controlled by adjustment of the manually operable valve 41 in the conduit 46.

A comminuted, granular or powdered material may also be positively fed to the combustion space 36 through the hollow member 24. In many instances such material is simply heated to an ele vated temperature and mixes with and is entrained in the heated products of combustion discharged through the restricted outlet 40. This is particularly true where the particles of comminuted material are employed to provide a coating on asbestos shingles, bricks and other like products whose surfaces are coated or impregnated with a material, such as asphalt, for example. The subdivided material adapted to form such a coating may be colored to produce a finished surface which simulates the natural color of a product. Such coating material, which may be sand or the like, for example, may be heated to a red hot temperature in the combustion space 36 and then entrained in the heated products of combustion discharged through the outlet 46 in a high velocity gas stream. The heated material is forceably driven into the surfaces of the articles which are properly prepared to receive such material, and, since the particles of the material are in a highly heated state, the particles will burn their way into the surface and become firmly bonded therein.

The hopper and blower arrangement shown in Fig. 1 illustrates one manner of positively feeding comminuted or subdivided material to the burner [0, it being understood that various other expedients may be employed to effect feeding of such material to the combustion space 33. By adjusting the damper 5| in conduit 48 and the speed of movement of the agitator 52, the rate at which the comminuted or subdivided material is positively fed to the burner 19 can be readily regulated.

The inner and outer refractory wall parts of the burner Iii may be formed of a suitable high temperature refractory material, such as mullite, for example; and the hollow members 23 and 24, as well as the burner screen 2|, may be formed of a high temperature refractory material, such as beryllium oxide for example, which is capable of withstanding the high tem- ""7 peratures developed in the combustion space 36.

While an air blower is employed to feed the subdivided material to the hollow member 24 in a rapidly moving air stream, and such air tends to reduce the high temperatures developed in the combustion space 36, this is offset and minimiz'ed by the fact that the hollow member 24 is heated to a highly incandescent tmperature whereby the air passing therethrough is preheated and reaches an elevated temperature before it is discharged from the upper end of the hollow member 24 along with the entrained subdivided material.

By providing two separate hollow tubular members 23 and 24, either a vaporous fluid or comminuted or subdivided aterial may be separately supplied to the combustion space 66. In certain heating aplications it may be desirable, however, to supply both a gaseous or vaporous fluid and subdivided material simultaneously to the burner Ill.

The .gas stream discharged from the combus tion chamber 36 through its outlet 40 is at a temperature nearly equal to the temperature in the combustion chamber. In many instances it is desirable to produce a high velocity gas stream which .is at a temperature below that prevailing in the combustion space 36. This is particularly true when the gas stream of heated products of combustion, and medium entrained therein in the combustion space 36, is to be applied to a material whichrequires heating to an exact temperature or in a temperature range well below the temperature of the gas stream discharged through the outlet 40. The temperature of the gas stream discharged from the combustion space36 is reduced in the burner III by mixing with the discharged heated products of combustion a gaseous medium which is at a temperature lower than the temperature in the combustion space 36.

Such a gaseous medium capable of reducing the temperature of the heated products of combustion may be air or nitrogen, for example, adapted to be supplied under pressure through the conduits i8 to the inlet chambers H for flow through the passages 42. Such cooling gas supplied to the passages 42 mixes with the heated products of combustion issuing through the restricted outlet 40, and such mixture is then discharged from the burner ill at the discharge port 35 at a temperature depending upon the pressure at which the cooling gas is supplied to the passages 42 and at the rate at which such cooling gas mixes with the heated products of combustion. By controlling the delivery'pressure of the cooling gas, as by the manually operable valves IS, the temperature of the heated gas stream produced at the discharge port 35 can be accurately regulated through a wide temperature range from a low temperature to the temperature of the heated products of combustion discharged from the combustion space 36.

In Fig. 3 is shown another form of burner Illa generally like that illustrated in Figs. 1 and 2 in which a single hollow tubular, member 23a of refractory material extends from the exterior of the burner through the inet chamber Ila and burner screen |6a into a combustion chamber 36a. The combustion chamber 360. having a restricted outlet 40a is formed by a refractory wall 39a disposed within an' outer metal shell Ma. The shell lid is fixed to a base member Ha providing the inlet chamber Hz: to which the gaseous fuel mixture is supplied through a conduit lia. The hollow member 23a is secured in position in the base member Ila by a bushing 44:: which acts against suitable packing material 43a to provide a gas-tight seal at the bottom of the inlet chamber I211.

The burner Illa may be constructed generally like the burner I described above and shown in Figs. 1 and 2. Either a gaseous or vaporous fluid or a comminuted or subdivided material may be supplied to the combustion space "a during operation of the burner Illa, as in the embodiment of Figs. 1 and 2, to produce a high velocity gas stream of heated products of combustion in which the medium discharged from the upper end of the hollow member 23a is entrained.

It will be noted that in the burner Illa the upper end of the hollow member 23a terminates at a region closely adjacent to the restricted outlet a. The region at which the hollow tubular members terminate in the combustion spaces will vary depending upon the medium supplied thereto and the extent to which it is desired to heat such medium. For example, when cracking of a hydrocarbon fluid is desired, it may be preferable to terminate the hollow tubular member, through which such fluid is supplied, at a region some distance from the restricted outlet of the combustion space. On the other hand, when powdered or comminuted material is supplied through the hollow tubular member into the combustion space, each particle of the material can be heated to a red hot temperature very quickly. In such case it may be desirable to 'provide a hollow tubular member which terminates at a region closely adjacent to the restricted outlet of the combustion space, in the manner shown in Fig. 3.

In Figs. 4 and 5 is illustrated another form of burner for practicing the invention which comprises an outer metal shell 3") disposed about a refractory wall 3% which forms the combustion chamber 36b having a restricted outlet 4%. A side passage 53 extends from a side wall of the shell 3") to the combustion space 3612. By removing a removable cover plate 54 at the outer end-of the passage 53, the combustion of the gaseous mixture taking place in the combustion space 36b can be visually observed.

The refractory wall at the inlet end of combustion space 36b is formed and shaped to provide a cup-shaped cavity 55 having an opening 56 at the bottom thereof which extends downwardly to the exterior of the burner. A hollow metal sleeve 51, which is formed with an inlet chamber I2c at the lower end thereof to which a conduit 16b is adapted to be connected, snugly flts within the opening 56. The hollow sleeve 51 is threadedly connected to a shorter hollow mem- 60 her 58 whose upper end is internally threaded and terminates at a region at the bottom of the cup-shaped cavity 65. An outwardly extending flange 59 formed on the hollow member 58 bears against an abutment at the upper reduced portion of the opening 56, so that the hollow member 58 can be accurately positioned at the bottom of the cup-shaped cavity.

The upper internally threaded end of the hollow member 58 receives an externally threaded burner tip 60 formed of refractory material. The tip 60 effects distribution of the combustible gaseous mixture into a pluarlity of small gas streams passing through slots or channels 6| formed about the periphery of and extending lengthwise of the intermediate part and 9 underside of the enlarged upper end of the bumer tip 60. The upper ends of the slots 6i at the underside of the enlarged upper end of the burner tip flare outwardly toward thewall surfaces of the cup-shaped cavity 55.

The burner tip 60 is also provided with a central opening or aperture into the upper enlarged end of which is secured, as by a suitable high temperature refractory cement, the lower end of a hollow refractory tube 23b which extends toward the restricted outlet 40b. To the lower enlarged portion of the central aperture in the burner tip 60 is fixed one end of a metal tube 62, the lower opposite end of which extends exteriorly of the burner through an opening in the inlet chamber He. The tube 62 at its lower end is flxed in position by a bushing b which, together with suitable packing material 451), effectively seals the inlet chamber I20.

When the burner llib is operated, the combustible gaseous mixture supplied through the conduit llib into the inlet chamber I20 flows upwardly from the latter into the hollow metal sleeve 51. at the lower tapered end of the burner tip 60 about-the periphery thereof and flows through the channels or slots 6|. The gaseous mixture is discharged from the outlet ends '63 of the channels, at the underside of the enlarged upper end of the burner tip 60, and it is at this region that the burner flames are produced and maintained.

The individual flames produced at the outlet ends 63 of the channels 6| flare outwardly and project into the cup-shaped cavity 55 closely adiacent to and alongside the wall surfaces thereof. After an interval of time the gas flames maintained at the slot outlets 83 effect such heating of the surface of the cup-shaped cavity 55 that these surfaces become heated to incandescence, and thereafter the combustion of the gaseous mixture effected in the combustion space 38b effects such heating that the inner refractory lining of the space also becomes heated to a high incandescent temperature. Due to such heating of the inner wall surface of the combustion space 38b, substantially complete burnin of the gaseous mixture is accomplished within the space before the mixture reaches the restricted outlet llib.

As in the embodiment previously described, a suitable medium may be supplied to the hollow tubular member 23b which is discharged from the upper end thereof into the combustion space "b. Such medium, which may be either a comminuted or subdivided material or a vaporous or gaseous fluid, is rapidly heated to an elevated temperature in the combustion space 36b and mixes with and is entrained in the heated products of combustion discharged through the restricted outlet 40b as a high velocity gas stream.

The burner in Figs. 4 and 5 differs from the preceding embodiments in that only the hollow tubular member 23b extending upwardly from the burner tip 60 need be formed of refractory material. The tube. connected to the bottom part of the burner tip 60 and extending downwardly therefrom may be formed of ordinary metal. However, in order to compensate for any expansion or contraction of burner parts resulting from operation of the burner. the tubular member 82 preferably is provided with an inter- The gaseous mixture is distributed 10 mediate expansible and contractible portion 54.

While several embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the true spirit and scope of the invention, as pointed out in the following claims.

What is claimed is:

1. Heating apparatus comprising structure providing a combustion chamber provided with an inlet through which fuel to be burned is introduced and a restricted outlet through which the products of'combustion are discharged at a high velocity, means located in said inlet to form a plurality of small passages whereby the supply of fuel to said chamber is subdivided into a plurality of small flames, said means also being provided with an opening, and a conduit extending from the exterior of said chamber through the opening in said'means into said chamber and terminating adjacent said restricted outlet, whereby material supplied through said conduit will be discharged through said outlet with the products of combustion.

2. Heating apparatus comprising structure having a combustion chamber provided with an inlet and a restricted outlet, means extending across said inlet to form, a plurality of small passages through-which a combustible mixture can be admitted to. said chamber to burn therein in a plurality of flames, the products of combustion issuing from said outlet at high velocity, a conduit extending from the exterior of said chamber through said means into said chamber and terminating at a point adjacent to said restricted outlet, said conduit being substantially surrounded by flames issuing from said passages and completely surrounded by high temperature products of combustion, and means to supply a material to be treated through said conduit.

3. Heating apparatus comprising structure hav-' into said chamber and will be carried with the products of combustion through said outlet, means to supply material to be heated to said conduit. said structure being provided with passages surrounding a portion of said chamber, said passages terminating at a point beyond said outlet and in line therewith, and means to supply a medium capable of reducing the temperature of the products of combustion through said passages.

' FREDERIC O. HESS.

REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 292,944 Parson et al. Feb. 5, 1884 1,513,622 Manning Oct. 28, 1924 1,639,967 Reader Aug. 23, 1927 r 1,925,131 Brownlee Sept. 5, 1933

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