US2427545A

US2427545A - Internal-combustion gas burner

Info

Publication number: US2427545A
Application number: US516320A
Authority: US
Inventors: Jr Carl R Berger
Original assignee: Selas Corp of America
Current assignee: Selas Corp of America
Priority date: 1943-12-31
Filing date: 1943-12-31
Publication date: 1947-09-16
Anticipated expiration: 1964-09-16

Description

Sept. 16, 1947. c. R. BERGER, JR

INTERNAL-COMBUSTION GAS BURNER Filed Dec. 3l, 194.5

Patented Sept. 16, 1947y S PATE NT OFFICE INTERNAL-COMBUSTION GAS` BURNER Carl R. Berger, Jr., Philadelphia, Pa., assignor to Selas Corporation of America, a corporation of Pennsylvania Application December s1, 1943, serial No. 516,320

My invention relates to gas burners. and more particularly to gas burners for producing a high velocity gas stream consisting of highly heated products of combustion developed substantially entirely within a combustion chamber embodied in the burner. 1

It is an object of the inventionV to provide an improvement for gas burners of this type, so that heat will be more effectively liberatedl in the combustion' chamber and thereby increase the tem- 8 Claims. (Cl. 158-116) perature of the heated products of combustion.

y) flcation, and of which Figs. 1 and 2 are end and side vertical sectionalviews, respectively, of a gas burner embodying the invention; Fig. 3 is a sectional view, taken on line 3-3 of Fig, 1, to illustrate the burner more clearly; and Fig. 4 is a top plan view of the burner.

Referring to the drawing, the gas burner I Il embodying the invention'includes a base member II shaped to form an inlet chamber I2 communicating with an inlet opening I4 formed in a nipple connection I5. The nipple connection I5 is internally threaded to receive a conduit I6 through which a combustible fuel is delivered from a suitable source of supply.

The base member Il is formed with internal shoulders I1 above the inlet chamber l2 to receive an apertured member or burner screen I3 formed with a plurality of openings or passages I9. As shown, the burner screen I3 comprises a plurality of relatively thin plates stacked and closely heldA together. One face of each plate is fdrmed with a plurality of slots of relatively narrow depth, and the plates are stacked together with a slotted face of each plate, except one end plate, contiguous to and contacting a smooth face of an adjacent plate. Although not to be limited thereto, the thin plates forming the burner screen I8 may be formed of suitable refractory material.

ATo the top surface of the base member Il is secured a slotted clamping plate 20, as byl screws 2|, for example, which overlies anges or lugs 22 formed at opposing sides of the burner screen I8. In order to obtain a gas-tight seal about the a hollow rectangular shell comprising two similar or complementary wall parts, U-shaped in hori- 'zontal section, and having parallel ends or end walls 21, as shown in Fig. 3. The extreme edges of opposing end walls 21 at each end of the burner Ill are in abutting relation, as indicated at 28 in Fig. 3. l

'I'he closed ends or side walls 23 of the U- shaped parts are thicker in section than the end walls 21 and have the outer surfaces thereof conforming to the shape of the metal shell 25. The inner surfaces of the end walls 21 are straight throughout the heights of these walls, as best shown in Fig. 2. The inner surfaces of the side walls 2S include straight wall portions 30 extending upward from the plate 20 to anintermediate part of the outer refractory lining, and inwardly sloping wall portions 3| terminating at the upper part of the metal shell 25, as shown most clearly in Fig. 1. y

A second inner refractory wall or lining is disposed within -the outer refractory lining just -described and forms a combustion chamber 32. The inner refractory lining is also formed by a hollow rectangular shell comprising two similar or complementary wall parts, U-shaped in horizontal section, and having parallel ends or end walls 33 over which snugly iit the ends 21 of theouter refractory wall parts, as shown in Fig. 3. 'Ihe extreme edges of opposing end walls 33 at each end of the burner I0 are in abutting relation at 34, as shown in Fig. 3. Y

The inner surfaces of the end walls 33 'are straight throughout the heights of these walls. as seen in Fig. 2. The closed ends or side walls 35 of the U-shaped parts forming the inner rewalled portions 36 are vertically ribbed, as shown most clearly in Figs. 2 and 3, to increase the surburner screen I8, a, gasket `23 formed of a suitable face area presented by these portions of the inner refractory lining. The bottom edges of the inner refractory lining overlie and ilt snugly against the peripheral edges of the narrow portion of the refractory lining, the bottom edges of the side walls of the inner refractory lining are provided with raised bosses which butt against the bottom edges of the side walls 28 of the outer refractory lining, as shown in Fig. l. In addition, the side walls 3i of the inner refractory lining are formed with vertical extending raised portions 4I of the shape shown in Fig, 3, which butt against both the straight wall portions 3l and sloping wall portions 3l of the side walls 2l of the outer refractory lining.

The liv-shaped parts forming the inner refractory lining are provided at their upper ends with flanges 42 extending into and ntting in notched or recessed portions formed at the top edges of v15 snugly neted within an outer wall part. the outerrefractory lining is fixed to the inner surface of the shell 2i by a coating 44 of a suitable high temperature fire-brick cement. The flanges 42 of the inner refractory lining are also fixed at 4I to the recessed portions of the outer refractory lining by such high temperature cement. as shown in Fig. 1. Likewise, the abutting edges of the end walls 21 and 33 of the outer and inner refractory linings, respectively, may be united by high temperature cement. The recesses formed at the top surface of the flanges 42 are also filled with high temperature f lrebrlck cement which. after hardening, firmly anchors the screws 43 in position and at the same time protects the screws from the high temperatures developed `in the inner refractory lining during operation of the burner.

When it is desired to employ the burner i0 for heat treating purposes, a combustible fuel mixture, such as, for example, air and ordinary 'city gas, natural gas or the like, is supplied thereto through the conduit I4 from a suitable source of supply. When the burner. I0 is relatively cool and at the temperature of the surroundings, the fuel mixture supplied thereto passes through the inlet chamber .|2, burner screen I8 and chamber 32 from which it is discharged through the outle or discharge orifice 3l.

'I'he combustible fuel mixture is initially supplied to the burner In at a relatively low pressure, such as ilve or sur inches of water pressure, for example, so that the fuel mixture discharged from the .chamber 32 can be ignited to produce and maintain a flame at the discharge orifice 3l. When a ilame'is being maintained at the discharge orifice 38, the pressure ofthe fuel mixture supplied to the burner i0 is -then reduced sufficiently to-cause the flame to backfire from' the discharge orifice 33 onto the burner screen i3 in-chamberJZ. When this occurs a plurality of flames are produced and maintained at the upper ends of the openings Il.

temperatures developed in combustion cham-- thermal shock, but primarily for its insulating.

When the flames are being maintained within I 4 temperature which may reach inca'ndescence.l Due to heating the inner refractory lining to a high temperature, complete combustion of the fuel mixture is effected in chamber 32 before the fuel mixture reaches the discharge orifice 33. From the orifice 33 is discharged a high velocity jet or stream of'heated gases consisting substantially entirely of the `heated products of combustion.

It is desirable in gas burners like that illustrated and just described to discharge the heated products of-combustion at a maximum velocity and at the highest temperature possible. This is so because the rate of heatl input effected by the gas stream discharged from the burner outlet 38 is dependent upon the temperature of the heated gases forming the gas stream, and therate at which the gases are deliveredfrorn the refractory lined combustion chamber l2 embodied in the burner. In order to achieve this end it is necessary to give up to the heated products of combustion substantially all of the -heat liberated in the-refractory lined combustion chamber 32, and to reduce to a minimum the loss of heat through the walls of the combustion chamber. In reducing heat loss through the walls of the combustion chamber to a minimum and thereby maintaining exceedingly high combustion chamber temperatures, it is necessary to provide an inner refractory lining which will, for prolonged periods f use, be capable of withstanding intense heat shock and temperature differential within the combustion chamber without fusing, blistering or cracking. l

By embodying a double-walled refractory com- Nbustion chamber in the burner III, an arrangement is provided in which heat loss through the burner walls is reduced considerably. Further, the inner and outer refractory linings may be formed of dierent refractory materials each possessing such properties that optimum burner performance will be obtained. Thus, the inner refractory lining, because of its being subjected to high combustion temperatures developed in combustion chamber'32, is preferably formed of a refractory material having relatively high resistance to thermal shock over a wide temperature range. Further, the inner refractory lining is preferably 'formed ofl a refractory which will provide a wall structure of exceptional strength and have, rigidity underall burner operating conditions. In addition, the inner refractory lining must possess such physical properties that the inner highly heated surface will withstand the relatively high pressure of the gases at the high ber 32.

` Since th'e outer refractory lining is not directly subjected to the intense highA temperatures developed in combustion' chamber 32, the refractory material selected for the outer refractory lining is not chosen so much for its ability to withstand or poor thermal conducting properties. In this way an effective thermal insulating wall structure is provided about the combustion chamber 32 which will effectively stand up for prolonged periods of use to produce a high temperature gas stream of high velocity and to which is given up substantially all of the heat liberated in combustion chamber 32.

In order to improve further the 4insulating characteristics of the combustion chamber wall structure, the air spaces 39 are provided between Jthe inner and outer refractory linings.

The

/` 'I'he combustion of the spaces 39 provide regions in which the air is more-Y or less stagnant. thereby improving the insulating characteristics of the two side walls of the burner I0. In addition, the provision of the air spaces outer refractory lining and stand up under the uses normally encountered by a gas burnerlike that of burner i3.

Although not to be -limited thereto, the inner yrefractory wall or lining may be formed of silicon carbide because of its high resistance to heat shock and rigidity and strength at high temperatures. i

In the usual type of gas burnei` producing a bright and luminous flame burning in the open, the burner is usually positioned with respect to the obiect to be heated so that the tip of the flame, which is the region at the highest temperature, impinges the surface of the object. In gas burners operating with such a bright and luminous ame in the open, combustion or burning of the gas mixture takes place in the open. Under these conditions, combustion of the gas mixture is not taking place at the highest possible temperature because the he'at liberated by the combustion reaction is given up to the cooler surroundings.

The burner i0 of the invention is characterized by the absence of a bright and luminous ame during normal operation of the burner. It is only when the burner I0 is rst started that a flame is momentarily maintained at the elongated slot or discharge orice 38, as previously explained. After the gas mixture has once been ignited,I the gas delivery pressure is reduced sufficiently to cause backflring into the chamber 32V, so that burning of the gas mixture will take place at the top surface of the burner screen I8.

Each of the burner :dames initially produced at the upper surface of burner screen I8 consists of an inner cone of unburned gas and air and an outer cone constituting the portion of the flame in which the combustion reaction is taking place. When operation of the burner I is rst started and the inner refractory lining is relatively cool, the inner cones of the individual ames extending into the combustion chamber 32 are relatively long in length. As the inner refractory lining becomes heated. the inner cones of the individual flames become increasingly shorter and (shorter. When the surfaces of the inner refractory lining become heated to a high temperature approaching incandescence, the inner cones of theindividual ames become appreciably shorter from their original lengths when initially produced. It may be stated that under Y gas mixture is effected substantially entirely within the combustion chamber and heated products of combustion are discharged from the outlet,` 3,8 at an elevated temperature of 3200 F. and higher. Since the theoretical flame temperature of a gas mixture of air and ordinary gas is about 3700 F., it will t be seen that a, gaseous source of heat is made available by the burner I0 of the invention which is at a temperature approaching theoretical name temperature. f

Since the gas mixture is introduced into the combustion chamber 32 at a temperature of about 70 F. and heated to a temperature of 3200 F.

and higher, the gases expand at least seven fold Yand at a rate directly proportional to increase in absolute temperature. In view of the fact that combustion of the gas mixture is effected substantially entirely within the .vcombustion chamber 32 and the gases undergo considerable expansion, as just pointed out, any increase in the gas mixture delivery pressure consistent with the intended mode of operation effects an enormous increase in the rate at which the heated gases are discharged from the combustion chamber.

VBurners like the burner I0 have been successfully used commercially with gas mixture delivhaving an outlet slot or discharge orifice 2" x ,1/8",I

and operating at a gas mixture delivery pressure of about 5 lbs.` per ,square inch, it may be stated vthat the heated gases issue from the outlet at temperatures of 3200 Ff and higher. In addition, it may be stated that these heated gases, consisting substantially entirely of heated products of combustion, are discharged from the burner at an average velocity of 900 feet or more per second and at a maximum velocity of about 1300 feet or higher per second. Burners of Vthis type have been operated experimentally at gas mixture delivery pressures in excess of 5 lbs. per square inch and have produced high temperature gas streams at correspondingly higher temperatures and increased velocities.

An important operating character of the burner III is that the combustion chamber 32 is main- .'tained above atmospheric pressure during normal i 50 doperation of the burner.

screen I8, is such that the gas pressure, will be maintained above atmospheric pressure in the combustion chamber 3.2 when the gas mixture is delivered at a pressure coming within the normal operating range usually encountered in practice. When the gas mixture is delivered at pressures up to 5 lbs. per square inch, and even at pressures above this delivery pressure, the ratio of the size of the outlet to that of the inlet of the combustion chamber is such that the gas pressure in the combustion chamber will be above atmospheric pressure. The maintenance of the combustion chamber above atmospheric pressure, together with the heating ofthe inner refractory surface of the combustion chamber to a high temperature, is of considerable importance tainment of -a high rate of combustion.

When operating with a combustible gas mixture of air and city gas having a rating of about 500 B. t. u.v per cubic foot, and at a gas mixture delivery pressure of about 5 lbs. per square inch, burners like that just described and illustrated are capable of liberating 40,000,000 or more B. t. u. per hour per cubic foot of combustion chamber space. In view of this high rate of heat liberation, the scope and field of application oi' burners like the burner Il have been widened considerably. Although I do not wish to be limited thereto, it is my belief that the gas mixture introduced into the combustion chamber i2 is subjected to intense heat radiated from the highly heated surfaces of the inner refractory lining, thereby effecting complete burning of the y gas mixture within the combustion chamber before the gas mixture reaches the outlet 38.

The double-walled inner refractory linings con tributes materially to the excellent operating performance of the burner I0. Moreover, the insulating characteristics of the burner wall structure are improved-by providing the air spaces 39 at two of the side walls of the burner. this arrangement the loss of heat through the walls of the combustion chamber I2 is reduced to a minimum, as explained above,'and substantially all of the heat liberated -in the refractory lined combustion chamber 32 is given up to the heated products of combustion. The enormous expansion of the gases eiTected in the combustion chamber 32, in addition to the high temperatures attained, provides a, source of gaseous heat capable of doing useful work in which largey volumes of heated gases are developed at exceedingly high temperatures substantially equal to the high temperatures prevailing in the combustion chamber.

While I have shown two air spaces 39 at opposite side walls of the burner i0, it will be appar- 2. A gas burner comprising a base having an opening and wall structure projecting therefrom forming a combustion chamber having an inlet communicating with the opening and a restricted outlet, said wall structure including an inner pair of complementary wall parts of refractory material extending axially of the burner and forming an inner wall for the chamber and an outer pair of complementary wall parts of refractory material disposed about and substantially coextensive in length with the inner walll parts and forming another -wall surrounding the inner wall, each of said wall parts being U-shaped in section in a plane transverse to the axis of the burner and including a closed side and spaced apart ends transverse thereto and abutting the spaced apart ends of the complementary wall part, the wall parts being formed so that the ends of the outer wall parts snugly t over the ends of the inner wall parts when each inner wall part is nested within an outer wall part, at least one of the closed sides of each pair of nested wall parts having projections extending from a surface thereof adapted to bear against-the closed side of the other wall part in nested relation therewith to maintain the closed sides of the inner and outer wall Darts in spaced apart relation and form gaps therebetween, and means to maintain the regions of the wall parts adjacent to the inlet firmly anchored to the base.

3. A gas burner comprising a base having an opening and wall structure projecting therefrom ent that such air spaces may be providedat all of the side walls of the burner. Also, it may be desirable to iill the air spaces 39 with crumbled grog or the like to break down the dead air spaces 39 into smaller air spaces with a suitable heat -insulating medium. Instances will also arise where it may be desirable to provide a burner like burner i0 in which no air spaces 39 are provided and the inner and outer refractory linings are more or less in abutting relation at all of the side walls of the burner. In such case, suilicient allowance may be made in dimensioning the inner and outer refractory linings so that the inner refractory lining can expand freely during burner operation and snugly t and butt` against the outer refractory lining. I therefore aim in the following claims to cover all changes and modifications which fall within the true spirit and scope of the invention.

What is claimed is:

l. A gas burner comprising a base and wall structure forming a combustion chamber having an inlet and a restricted outlet, said wall structure including an inner wall of high temperature refractory, material defining the restricted outlet a d having raised portions at the exterior thereof a acent the inlet and outlet, a second wall of refractory material disposed about the inner wall having a recess forming a shoulder adapted to receive the raised portion of the inner wall adjacent the outlet, the inner and second walls at the inlet end of the chamber being adjacent to said base and extending therefrom, and an outer metallic shell removably secured to the base and enveloping the second wall, said shell having an opening at the r'egion of the restricted outlet and l acting against the raised portion of the inner wall adjacent the outlet, so that the raised portion of the inner wall adjacent the inlet will be firmly seated on the base.

, planeA transverse to the axis of the burner and including a closed side and spaced apart ends transverse thereto and abutting the spaced apart ends oi'l the complementary wall part, the wall parts being formed so that the ends of the outer wall parts snugly llt over the ends of the inner wall parts when each inner wall part is nested Within an outer wall part, at least one of the closed sides of each pair/'of nested Wall parts having a rib integral therewith which extends lengthwise of the combustion chamber and is adapted to bear against the closed side of the other wall part in nested relation therewith to maintain the closed sides of the inner and outer wall parts in spaced apart relation and form gaps therebetween, and means to maintain Ythe regions of the wall parts adjacent to the inlet firmly anchored to the base.

4. A gas burner comprising a base having an opening and wall structure projecting therefrom forming a chamber provided with an outlet and an inlet communicating with the opening having a multiplicity of apertures, said wallstructure including an inner pair of complementary wail y parts of refractory material extending axially of Vthe burner and forming an inner wall for the chamber and an outer pair of complementary wall parts of refractory material disposed about and substantially coextensive in length with the inner wall parts and forming another wall surrounding the inner wall, each of said wall parts being U- shaped in section in a plane transverse to the axis of the burner and including a closed side and 9 spaced apart ends transverse thereto, and abutting the spaced apart ends of the complementary wall part, the wall parts being formed so that the ends of the outer wall parts snugly nt over the ends of the inner Wall parts when each inner wall part is nested within an outer wall part, means including refractory material formed integrally with at least one of the closed sides of each pair of nested wall parts which is adapted to bear against the closed side of the other wall part in nested relation therewith to maintain the closed sides of the inner and outer Wall parts in spaced apart relation and form gaps therebetween, and means to maintain the regions of the wall parts adjacent to the inlet rmly anchored to the base.

5. A gas burner comprising a base having an opening and wall structure projecting therefrom providing a combustion chamber having a restricted outlet in the form of a slot and an inlet communicating with the opening having a multiplicity of apertures, said wall structure including an inner pair of complementary wall parts of refractory material extending axially of the burner and forming an inner lining and the restricted outlet for the chamber and an-outer pair of complementary wall parts of refractory material disposed about and substantially coextensive in length with the inner wall parts and forming another wall surrounding the inner wall, each of said wall parts being U-shaped in section in'a plane transverse to the axis of the burner and including a closed side and spaced apart ends transverse thereto and abutting the spacedapart ends of the complementary Wall part, the Wall parts being formed so that the ends of the outer wall parts snugly fit over the ends of the inner wall parts when each inner wall part is nested within an outer wall partl means including refractory material formed integrally with at least one ofthe closed sides of each pair of nested wall parts which is adapted to bear against the closed side of the other wall part in nested relation therewith to maintain the closed sides of the inner and outer wall parts in spaced apart relation and form gaps therebetween, and means to maintain the regions of the wall parts adjacent t the inlet firmly anchored to the base.

6. A gas burner comprising a base having an opening recessed to form a seat, and wall structure forming a combustion chamber having an 10 the walls adjacent to the inlet nrmly seated on the clamping plate, the opening at the other end of the shell being disposed at the region of the restricted outlet.

7. A gas burner comprising a base having an i opening, and wall structure forming a combustion chamber having an inlet and arestricted outlet, said wall structure including an apertured member, means for removably holding the apertured member in position at the opening in the base, the apertured member serving as the inlet and having a portion thereof projecting from the base toward the outlet, an inner wall of high temperature refractory material having the end thereof adjacent to the`inlet adapted to bear against the base and overlie the projecting portion of they apertured member, a second wall of refractory material disposed about the inner wall and having the end thereof adjacent to the inlet adapted to bear against the base, at least one of the walls having ribs integral therewith which extend lengthwise of the combustion chamber, the ribs on the one wall being adapted to bear against the other wall to hold at least parts of the walls in spaced apart relation and form a gap therebetween. and means to hold,y the outer wall positioned against the inner wall and both of the walls against the base includingan open-ended metallic shell removably secured at one open end thereof to the base, the opening at the other end of the shell lbeingdisposed at the reglonof the restricted outlet.

of high temperature refractory material having p the end thereof adjacent to the inlet adapted to inlet and a restricted outlet, said wall structure including a flanged apertured member positioned at the opening in the seat therein, the apertured member serving as the inlet and having the narrow portion thereof projecting from the base toward the outlet, means-including a slotted clamping plate removably secured to the base for retaining the apertured member in position at the opening. the narrow portion of the apertured member passing through the slotted plate, an inner wall of high temperature refractory material having an end thereof adjacent to the inlet adapted to bear against the clamping plate and overlie the narrow projecting portion of the apertured member, a second wall of refractory material disposed about the inner wall and having an end thereof adjacent to the inlet adapted to hear against the clamping plate, at least one of the walls having projections extending from a surface thereof adapted to bear against the other Wall to hold at least parts of the walls in spaced apart relation and form a gap therebetween, and means including an open-ended metallic shell which envelops the walls and is removably secured at one open end thereof to the base to hold the ends of UNITED STATES PATENTS yNumber Name Date 1,689,551 Hammond June 2, 1926 1,704,875 Vaughn Mar. 12, 1929 2,364,108 Swentzel .;-\Dec. 5, 1944 2,101,947 Kenzie Dec. 14, 1937 FOREIGN PATENTS Number Country Date 448,663 Great Britain June 12, 1936 bear against the base and overlie the projecting portion of the apertured member, a second wall of refractory material disposed about the inner wall and having the end thereof adjacent to the inlet adapted to bear against the base, lat least one of the walls having projections extending from a surface thereof adapted to bear against the other wall-to hold at least parts of the walls in spaced apart relation and form a gap therebetween, and means acting to hold the outer wall snugly pressed against the inner Vwall and hold both of the walls against the base including an outer shell removably secured to the base, the shell having an opening at the region of the outlet 1and enveloping a `major portion of the outer wa CARL R. BERGER, JR.

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