US2591263A - Grid gas burner - Google Patents

Description

April 1, 1952 R. E. JAMES ETAL 2,591,263

GRID GAS BURNER Filed April 18, 1947 2 SHEETS-SHEET 1 1!!!! '1 WHHH g 40% IN V EN TORS /?/CHAR.D [T (/4 MES.

4455/" z/. ZAMPERE R. E. JAMES ET AL GRID GAS BURNER April 1, 1952 2 SHEETSSHEET 2 Filed April 18. 1947 W mi T. .f mm WWW J m W E M R4 B Patented Apr. 1, 1952 GRID GAS BURNER Richard .E. James, Pasadena, and Albert J. Lampert, Walnut, Calif, assignors to Rheem Manufacturing Company, Richmond, Calif., a corporation of California.

ApplicationApril 18 1947, ScrialNo. 742,244

' Our invention relates to gas burners, and has particular reference to a burner adaptable for use in connection with, but is not to be limited to water heaters.

An object of our invention is to produce. a gas burner of the cast type which is simple and inexpensive to manufacture and wherein a maximum of port area and B. t. u. output is obtained on a relatively small burner.

It has long been the purpose of the: industry to produce a relatively small gas burner which has a relatively large heat output and which contains the features of a stable flame, good flame characteristics, and is free from flame lifting or flash back.

In order to function eifectiveiy the raw gas which is introduced from the supply line into the burner must be mixed with a certain quantity of air to insure complete combustion. Usually the amount of air is approximately nineor. burner would require approximately 10 cubic feet of air for complete and efficient combustion of the fuel. The air may be introduced in two Ways. A portion of it may be introduced as primary air; that is, air which is introduced into the burner through the venturi by the injection of a stream of. raw gas from an orifice passing through the air: medium, or it may be mixed with the gas as secondary air; that is, air which is supplied. at the point offcombustion surrounding thev flame.

Considerable variation is permitted for complete combustion in the relation between the amount of primary and secondary air which the design. of the. burner permits. In other words, eflici'entiburning may be obtained by the use of, for example, 40% primary air and 60% secondary air or conversely by the use of, for example, 60% primary air and 40% secondary air. It is clear that ifiai larger percentage-of primary air is=introduced. a smaller percentage of secondary air must be introduced for complete combustion.

In a burner where alar'ger proportion of the air is introduced as primary air, it becomes possible' to obtain good flamecharacteristics and complete combustion with a closer spacing of the outlet ports. It is a further object of our invention to produce a gas burner wherein a relatively large amount. of primary air is introduced into the raw gas, and, therefore, the necessity of's'econ'dary air is reduced. A closer location of the ports. or a larger port area for a given size gas burneri'sxthus. permitted. which results in a rela- 5- Claims. (Cl. 158-116) 2 tively larger B. t. u. output with a relativel small burner head.

In most of the cast type gas burners heretofore known to the industry, the ports have either been drilled or if the burner is a. two-piece construction the ports may be milled as slotsbetween the point of juncture between the two pieces. This is not only costly from a standpoint of manufacturing, but results in a fixed port size which does not permit of ready adjustment in the event of dilierent types of fuel being used.

For example, different port requirements are: met

in the cases of natural gas and manufactured gas.

A further object of our invention is to produce athree-piece gas burner having a spacer or grid betweenthe" adjoining, faces which creates the ports and which permits of ready adjustmentof the port. size: by changing. the-gauge or thickness of the grid member.

It is a further object of our invention to produce a gas burner of the multiple-piece cast type construction wherein the'necessary machining is reduced to a minimum.

In gas burners having ports which are" formed with a relatively large crossesectionalarea, means must be provided. to prevent flash back into the interior of the burner. This is; especially true where relatively larger proportions of primary' air are being used.

It is a further: object of our invention to provide a simple type or constructiondna:gasburner" wherein sufficient port; depth can: be attainedwith: a minimum of machining. costs, which will pre-' vent flash back;

The heat output of a given size gas: burner will clearly be dependent upon the amount or gas which. can be discharged throughpand effectively burned by said burners. Itwilll be. clearthatincreasing thev volume of gas flowing through the standard. type gas burner of a given size will, or

necessity, increase the velocity of discharge of gases from. the burnerports; Attempts to'fmcrease; this velocity beyond asafe limit result' in liftingior the flame from the burner, a condition streamline flow of the gas which permits an introduction of larger quantities of primary air and which permits the use of larger volumes of combustible mixtures through the burner without resulting in a high discharge velocity from the port which would lift the flame.

Other and further objects and advantages of our invention will become apparent from the drawings and the specifications relative thereto.

In the drawings:

Figure 1 is an elevational view of a gas burner embodying the principles of our invention.

Figure 2 is a plan view of the burner shown in Figure 1.

Figure 3 is a sectional view taken on line 3-3 of Figure 1.

Figure 4 is a sectional view taken on line 4-4 of Figure 3.

Figure 5 is an enlarged fragmentary view showing the details of the peripheral edge of the burner shown in Figure 1 taken on line 5-5 of Figure 4.

' Figure 6 shows a modification of the burner illustrated in Figure 3.

The burner comprises essentially a base designated generally [0, a cap II and a spacing and port forming grid l2.

' The base I is formed with a standard Venturi mixing chamber l5. The Venturi I is closed at the end by a plate l8 having an aperture [6 in the end thereof adapted to receive a gas jet H, which forms an integral part of the casting of the base Ill. The plate i8 is provided with one or more airinlet openings I9 and a regulating or damper plate 25. The regulating plate 20 is formed with a central aperture 2i adapted to fit over a boss 22 centrally located in the plate l8 and to rotate thereabout. The plate 20 also has an aperture 23 therethrough adapted to register with the aperture I9 for the admission of air. A set screw 24 is threadedly mounted in the plate l8 and is adapted to secure the adjusting plate 20 in the desired position.

The Venturi mixing chamber I5 merges into a frustro conical or flared section 30 which is disposed at right angles to the axis of the venturi l5. It will be notedthat the merger is gradual and smooth by means of a substantially large radius section 3|. The purpose of having a substantially large radius at the point of merger is to prevent any abrupt change in the direction of gas flow which might result in turbulence. The 7 lower side of the discharge end of the Venturi 33 is formed with a relatively thicker section and a threaded bore 34, the purpose of which will be explained later.

The frustro-conical or flared section 36 merges into an annular flat surface or ring 35, the upper and outer corner of which is chamfered as at 36. The purpose of the chamfer 36 will be explained later.

Inshowing the frustro-conical section 30 integral with the venturi l5 it is not to be understood that we intend to thereby limit our invention to such integral construction. It should be readily apparent that the frustro-conical section and the Venturi mixing chamber [5 could be made 7 base member i 0 are assembled by means of a bolt 45 disposed'through the bore 44 and threaded into the bore 34.

The underside of the surface of revolution of the arcuate element 42 is formed with a plurality of locating lugs 45.

As will be seen in Figure 5, the annular ring 40 is formed with a peripheral undercut section 50 forming a peripheral lip 52. The purpose of the lip 5| is to prevent the condensation of moisture on the burner from running back into the burner ports.

The vertical section 4| and the depressed center 43 define What is termed as a drip cup, the purpose being to collect any condensation and to prevent its running back into the port area. The moisture collecting in the center 43 evaporates because of the heat of the burner, rather than interfering with the flame characteristics or burning function of the burner.

As will be seen from Figure 3 the spacer and port forming grid [2 comprises a ring 55 having a thickness t (see Figure 5) and a plurality of radially disposed uniformly spaced fingers or projections 55 defining a plurality of parallelsided radially disposed notches 51.

The spacing lugs 45, heretofore referred to, are so disposed on the surface of revolution of the arcuate element 42 that when the cap Ii is assembled on top of the grid ii, the lugs 46 will fit snugly inside of the ring 55 thereby centering it with respect to the cap l2. It will be readily apparent that the bolt 45 disposed through the bore 44 centers the cap with respect to the base H3. The radial depth of the slot 51 is substantially greater than the width of the adjacent faces of the base I i! and the cap ll so that a passage is defined between the adjacent faces of the cap II, the base It, and the side walls of the notches 51. This passage is the port through which the combustible gas passes. As will be seen in Figures 3 and 5, the maximum diameter of the grid I 2 is substantially smaller than the diameter of the undercut section 50 of the cap ll so that an annular shoulder 60 is formed thereby. The purpose of this shoulder 63 is to act as a flame spreader;

The chamfered section 36 permits the inducement of a greater supply of secondary air through the individual port flame so that secondary air can be introduced into the port flamefrom the bottom and two sides simultaneously, thus resulting in better flame characteristics and a more complete combustion.

Referring to Figure 6, wherein we illustrate a modified form of a gas burner embodying the principles of our invention, numerals similar to those in Figures 1 to 5 inclusive designate similar parts. The principal modification lies in the means for centering or locating the grid 12 and the cap H with respect to the base If]. As will be noted, the center stud 45 has been eliminated. The flared section 3|! of the base Ill is provided with a plurality of bosses 15 having avertically threaded bore H therein adapted to receive a bolt 12. v

The cap I! is formed with a plurality of bores 73 in alignment with thevertically threaded bores 7! adapted to receive the bolts 12. It will be understood that the bolts 12 are sodisposed and spaced that they contact the inner periphery of the annulus 55 thereby serving as locating and securing means to center the grid l2.

It will be noted that the space between the flared section 30 and cap ll decreases as it progresses outwardly 'to the peripheral edges of the burner. The purpose of this is so that a constant volume and, therefore, constant velocity may be maintained as the gases progress toward the burner port. As the gases progress to the periphery of the burner the diameter of the section increases so that the cross-sectional area must be uniformly decreased to maintain a constant volume. Upon reaching the periphery of the burner, the cross-sectional area. has become substantially equivalent to the port area so that the minimum of turbulence results in the gasflow; therefore, a more stable flame is obtained.

It will also be noted that a burner has been permits. the handling of larger volumes of gasthrough a given size burner; The streamline flow also results in the ability to utilize a higher velocity of gas through the venturi. [5, thereby permitting greater quantities of primary air to be introduced through the aperture i9 and necessitating less secondary air so that the ports may be placed closer together.

A further advantage in our invention lies in the fact that one burner design or set of pattern molds may be used to produce a burner which Will handle a wide variety of gaseous fuels. It is well known that port area requirements differ between natural gas and manufactured gas. This can be readily adjusted in a burner embodying our improvement by changing the thickness t of the grid l2.

While we have herein shown and described our invention in what we have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of our invention, which is not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a gas burner having a gas and air inlet and a mixing chamber, a burner head in communication with said mixing chamber comprising a truncated conical section having a peripheral flange defining the upper edge thereof, a cap superadjacent and co-axial with said conical section and being formed with a depending conical portion within and spaced from said conical section, said cap being formed with a peripheral flange coaxial with said first-mentioned peripheral flange, a spacing and port forming grid removably disposed between, and serving to vertically space, said peripheral flanges and adapted to define in conjunction therewith gas ports, said grid comprising an annulus having a major diameter smaller than the minor diameter of said flanges and a plurality of radial fingers extending outwardly from the annulus and terminating substantially inside the outer periphery of said flanges, said conical section and said cap being adapted to deflne a relatively smooth annular passage having a substantially uniform cross-sectional area throughout the major portion of said passage adapted to cause a streamlined fiow of gases therethrough, said annulus being positioned in the outer regions of said passage and being adapted to cause a turbulence at the entry of said ports to thoroughly mix gas and primary air.

2. In a gas burner having a gas and air inlet formed with a relatively flat upper face, a. cap

superadjacent and co-axial with said conicalzsection and. being formed with. a depending conical portion. within and spaced from said conical section, said cap being formed with a. peripheral.

flange coaxial with the flange of said. conical. sec.- tion. and. having a relatively flat undersurface, a. spacing and port, forming grid removablyrheld between, and. serving to vertically space, said peripheral flanges and. adapted to definein: conjunction therewith rectangular gas ports, said grid comprising anannulus having a major diameter smaller thanv the minor diameter of: said flanges andv a plurality of radial fingers. extending outwardly from the annulus between said flanges and terminating substantially inside the outer periphery of said flanges, said conical section and said cap being adapted to define a relatively smooth annular passage having a. substantially uniform cross-sectional area. through out the major portion of said passage adapted. to cause a streamlined flow of gases therethrough, said annulus being positioned'in thev outer region of said passage and being adapted to cause a turbulence at the entry of said ports. to 'thoroughly mix gas and primary air, the flange of. said conical section being chamfered at the outer and upper edge thereof terminating adjacent the end of said grid fingers adapted to cause a. turbulent mixing of gas and secondary air, thereby preventing lifting of flame fingers from the gas ports.

3. In a gas burner having a gas and air inlet and a mixing chamber, a burner head in com-- munication with said mixing chamber comprising a truncated conical section having a. peripheral flange defining the upper edge thereof, a. cap superadjacent and co-axial with said conical section and being formed with a depending conical portion within and spaced from said conical sec- :tion, said cap being, formed with. a peripheral flange coaxial with the flange of said conical section, a spacing and port forming grid removably held between, and serving to vertically space, said peripheral flanges and adapted to define in conjunction therewith rectangular gas ports, said grid comprising an annulus having a major diameter smaller than the minor diameter of said flanges and a plurality of radial fingers extending outwardly from the annulus between said flanges and terminating substantially inside the outer periphery of said flanges, said conical section and said cap being adapted to define a relatively smooth annular passage having a substantially uniform cross-sectional area throughout the major portion of said passage adapted to cause a streamlined flow of gases therethrough, said annulus being positioned in the outer region of said passage and being adapted to cause a turbulence at the entry of said ports to thoroughly mix gas and primary air, a downwardly extending relatively sharp peripheral lip spaced outwardly from and above the lower surface of said cap flange adapted to prevent moisture condensates from flowing into the ports, the flange of said conical section being chamfered at the outer and upper edge thereof terminating adjacent the end of said grid fingers adapted to cause a turbulent mixing of gas and secondary air,

thereby preventing lifting of flame fingers from the gas ports.

4. In a gas burner having a gas and air inlet and a mixing chamber, a burner head in communication with said mixing chamber comprising a truncated conical section having a horizontally. extending peripheral flange defining the upper.

edge thereof, said peripheral flange being formed with a relatively flat .upper face, a cap superadjacent and co-axial with said conical section and being formed with a depending conical portion within and spaced from said conical section, said cap being formed with a peripheral flangecoaxial with the flange of said conical sectlonand having a relatively flat undersurface, a spacing and port forming grid removably held between, and serving to vertically space, said peripheral flanges and adapted to define in conjunction therewith rectangular: gas ports, said grid Toothprising an annulus having a major diameter smaller than the minordiameter of said flanges and a plurality of radial fingers extending outwardly from the annulus between said flanges and terminating substantially inside the outer periphery of said flanges, said conical section and said cap being adapted to define a relatively smooth annular passage having a substantially uniform cross-sectional area throughout the major portion of said. passage adapted .to cause a streamlined flow ot-gases therethrough, said annulus being positioned in the outer regions of said passage and being adapted to cause/a turbulence at the entryzof said ports to thoroughly mix gas and primary air, a downwardly extending relatively sharp peripheral lip spaced outwardly from and above the lower surface of said cap flange adapted to prevent moisture condensates from flowing into the ports, the flange of said conical section being chamfered at-the outer and upper edge thereof terminating adjacent the end of said grid fingers adapted to cause a turbudent mixing of gas and secondary air thereby preventing lifting of flame fingers from the gas ports.

5. A burner comprising a combination of a 4 minating in a peripheral flange, the axis of said conical section being vertical, a cap having a depending conical portion disposed within and above said conical section, thereby forming an outwardly flaring passage bounded by substantially conical surfaces and having a substantially uniform flow cross section, a, peripheral flange formed on the under surface of said cap, the under surface of said peripheral flange lying in a plane below the highest point of the upper surface bounding said passage, the inner edges of said flanges being positioned substantially one above,

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

UNITED STATES PATENTS Number Naxne Date 393,764 Kearns Dec. 4, 1888 819,018 Machlet Apr. 24, 1906 968,605 Ruud Aug. 30, 1910 1,923,394 Pickup Aug. 22, 1933 2,372,611 Stockstrom Mar. 27, 1945 2,428,998 Simpson Oct; 14, 1947 FOREIGN PATENTS Number Country Date 288,412 Germany Oct. 28, 1915 333,269 Great Britain Aug. 11, 1930 624,690 Germany W Jan. 28, 1936 615,805 Great Britain Sept. 16, 1947

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