US1898799A - Gas burner - Google Patents

Description

Feb. 21, 1933. A U WETHERBEE 1,898,799

GAS BURNER Filed July 2l, 1927 2 Sheets-Sheet l Feb. 21, 1933.

A. U. WETHERBEE GAS BURNER Filed July 21, 1927 Mm @f7 2 Sheets-Sheet 2 Patented Feb. 21, 1933 UNITI-:u STATT-:s

PATENT lori-Ica ASHUR 'U'.WIBTHERBE OF EVANSTON, ILLINOIS, ASSIGNOR TO AUTOGAS CORPORATION, F CHICAGO, ILLINOIS, A CORPORATION OF`DELAWARE GAS BURNER Application mea my 21, 1927. serial No. 207,399.

My invention relates to combustion of gaseous fuel, and the object of the invention is, broadly, to provide a more economical method of developing the heat generated by combustion ofV a gaseous fuel.

Vhile throughout the specification an claims herein I refer to the fuel as gas o r as being gaseous, I do not intend to limit the invention to the burning of a fixed gas, as the principles of the invention and the structural features herein disclosed are applicable to the combustion of any fuel of suiicient IinenessV that it acts substantially as a gas, that is, either vaporized, atomized, or pulverized to a degree where its combustion is capable of occ'urring with 'substantially explosive rapidity.

The specific problem which I-'have set out to solve is the provision of means and a meth-y od for burning city gas with high economy of heat development and transfer, and having the ability to stop and start operation of the burner with ease and certainty.

Where known methods of utilizing gas combustion for house heating service .have been employed, the cost has generally been excessive as compared with the cost of other fuels.

This is particularly'true in connection with known types of steam or` hot water systemsl which have been worked out in connection with the combustion of solid fuel. It has been a generally. accepted fact that with known types of steam or hot water boilers or furnaces, the substitution of gas fuel for the solid fuel, for which such boilers or furnaces were designed, has been out of the question because 'of ineliieiency and consequent excessive cost. v f

I have studied the problem and come to the conclusion that the reason for this is largely chargeable to the involved.

In the combustion of solid fuels there is always a mass of incandescent solid f uel which radiates heat. Where gas is'burned in the Bunsen type of burner, the flame, although short, has'very small heat radiating power. VIt appears to be a known fact that radiation from a given mass is a function of 59 tempera-ture of that mass and other character- `method `of heat transfer istics thereof. According to y the law of Stefan and Boltzman, radiation of heat from a given mass is approximately proportional to the difference between the fourth power of the absolute temperature of the heated massand the temperature of thel receiving surface. l

I have therefore taken, as the primary consideration in my invention, the possibility of transferring the heat from the combustion of the gas to the boiler walls by employing a mass of suitable character involving the maximum amount of heat radiation.

As ameans for providing the incandescent mass, I employ a mass of refractory of large superficial surface and of a loose granular or foraminated struc ure. In the preferred embodiment later to be described, I utilize' relatively thin flat chips of fire-brick laid on a solid base of refractory, The mass of loose refractory is heated by the combustion of gas within the body of the same.

I am aware of the employment of a'somewhat similar scheme of combustion within a mass of loose refractory, material originally patented by Lucke, but, as I shall point out later, there are very important and essential differences between my method and that of the prior art. I am also aware of the use ofv targets against which ablast burner is directed for the production of a radiating mass.

As I shall point out later, there lare serious objections to the use of such a method of combustion in the service in which my invention is particularly useful, namely, domestic heating.

For the development of maximum temperature'of the mass, the heat of the ame y must be as great as possible.y Ton this end no i excess air shouldbe admitted and, at the same time, .no unburned fuel should be passed out of the stack inthe interest of economy, Itis one of the essentials ofmy invention that there must be as complete mixing of the gas and supporting air as possible.

For house heating service, t/heeombustion should be capable of automatic contro1,i. e., preferably oif and l on, or, alternatively, up and down?, and, above all, there/ must be no danger ,of explosion at any time, no'r 10 should there be any appreciable explosive puff when the burner comes on after being shut ofi', or when the burner is shut olf after an operation. Likewise, the burner must be so constructed that the flame cannot strike back into vany confined space, both because of danger of explosion and because of danger through an orificeat such velocity that strikj ing back is not possible. I have tried flame arresters in the form of screens.

proven impracticable.

Y through a mass of refractory and project the According to my invention I employ only a thin bed of refractory of small mass supported on a bowl or plate of solid refractory,

which, at the same time, serves both as a nonconductor of heat and as a refiector of the heat of the mass of broken refractory. vI pass the flame or burning gases edgewise through this mass of loose refractory and carry on combustion at a high rate, i. e.,-- at substantially an explosive rate. The mass of loose refractory becomes incandescent and the radiation of heat occurs from the lateral face of the bed, i. e., from the exposed upper surface. The propagation of heat rays is therefore at substantially right angles to the general direction'of the burning gases. By this means only a small mass needs to be heated up to start and a largev radiating surface is provided. This 'great ratio of radiating surface to mass permits of a much greater rate of fuel combustion within a given space than has, been possible heretofore. Overheating of any part of the mass is preventedfy By propagation of heat radiation from the side or Hank of the path of gas travel, the length of the fiame is not of importance.

I am aware that it is old to fire upward heat in the same direction, but the prior art has this inherent defect', namely, that the central inner part of the mass attains a high degree of incandescence which can radiate only through interstices of the upper layers. The top layers are an` effective barrier to radiation from 'the central mass.l The major parts of the combustion is at the center and, hence, the top layers, from which effective radiation must occur, if'at all, are unheated by direct contact with the fire. If the input ofl cblmbustible-material is too great, then burning over the mass occurs. If the input is too small, the fire occurs wholly inside the.

m'aarrdrthetepllayer effectively prevents radiation.

They have with the accompanying drawings which illustrate an embodiment` of my invention.

Inthe drawings 1 v Fig. 1 is a plan `view of a burner embodying my invention;

Fig. .2 is a vertical section taken on the line 2-2 of Fig. 1 shown on an enlarged scale; and

Fig. 3 is a similar section through a portion of a'modification. j

Referring now to Figs. 1 and 2, I provide a bowl l, which is preferably constructed of sections. This bowl is made of fire-brick of high heat resisting and insulating properties. The sections are provided'with overlapping joints 2--2 so as to prevent an 'open crack where the sections come together.

eol

This bowl constitutes, inreality, a plate or disc of refractory insulating material for radiating the heat developed by the gas combustion upwardly and for preventing' the travel of heat there developed downwardly through the mass of the same.

' The section 3 contains, a recess- 4 in which there is disposed a sparkplug 5, the metallic shell of which is suitably grounded and the central electrode of which is connected through suitable control apparatus with a source of high tension current. l

I have, for the sake of clearness, omitted from the present disclosure the control apparatus, reserving the same for a later application. r

The electrodes of the spark plug are so disposed with respect to the path of gas travel as to be capable of igniting the combustible mixture readily.

The bowl or disc 1 is seated on a. supportflanges 9 at their lower ends and having-their upper ends disposed inpockets-10 and-.en-

gaging the lugs 11 through the medium of a threaded nut 12 by which the height of the posts may be adjusted.

and are apertured to receive thev clamping bolts 13 for clamping the mixer 14 `to the frame. 4

The mixer 14 comprises an outer gas chamber 15 and an inner air passage 16 within which is disposed a helical directing vane 17 for producing a whirling action of the air y passing through the passagel. The lower The lugs 11 on the ring 6 extend inwardly elbow 19 to an air inlet pipe 20, this pipe 20 in present case, are 45 degree Ls, with the gas end of the mixer 14 comprises a cylindrical threaded extension 18 connected by a pipe turn leading to the delivery of a fan or blower (not shown). The gas chamber communicates through a hollow lateral boss 21 and pipe iittings 22-23, which latter, in the inlet pipe 24. The air pipe 2() is provided wlth a throttle valve 25 and the gas pipe 24 1s provided witha similar throttle valve 26,

, these two valves being connected by a stem 27 and having a suitable opeiating. handle 28 for simultaneous adjustment. The gas pipe 24 leads to the cit main through a pressure regulator, prefer-abb for holding the gas pressure substantially A constant at all times. It is apparent that the butterfly valves 25 and 26 may beI independently regulated, but after the pressure' regulator for the gas has been suitably adjusted to the delivery of the blower connected to the air pipe 20, a simultaneous adjustment of air and gas, such as is possible by the butterfly valves 25--26, is desirable. f

The gas chamber 15 empties into the air passage 16 above the vane 17 through a slot 29. The gas and air then proceed from the outlet of the mixer 14 through a short passageway 30, which passageway is, in the form shown in Figs. 1 and 2, provided as a central aperture in adisc or plate 32 of firebrick, let into a recess or counterbore in the bowl or plate 1. The mixer 14 extends up through the central opening 3 2 which is formed in the ,disc or bowl 1. J

The opening 30 in the disc 32 is covered by a cap 33 of hre-brick or like material, supported on a central spider 34,=which spider has a series ofdirecting vanes preferably, but not necessarily, helically disposed in a direction opposite to the twist of the directing vane 17. The spider 34 is conically formed at its lower end to seat inthe conical upper end of the opening 30 for centering these two parts with respect to each other. The cap 33 i 1s preferably cemented tothe spider 34 so that the lower edge of the cap 33 is held a fixed distance above the plate 32 to provide a Aperipheral slot or outlet 35 around the periphery ofthe cap 33.

Along its outer margin, where the plate 32 comes flush with the surface of the bowl or disc 1, I provide a series of projections disposed a short distance from the rim of the cap 33. Flat chips 36 of {ire-brick rest at their inner edges against the capv33 and are supported away from the surface of the disc 32 and bowl 1 by the projecting ends or proj ections 37.

AChips graduated in size are then laid in overlapping rings in the fashion of shingles from the central chips 3S to the outer edge ly of the mercury type,

In effect, the bowl 1 comprises. the central disc 32 as Well as the iouter sections. central di c' 32 is, in this'case, made of single piece, but' this is not essential, since, due to the great heat to. which it is subjected, it expands and contracts and tends to crack in case it is made of one piece. y

As shown in Fig. 3, I refer therefore to make the fas passages o metal throughout until they ischarge into the zone of combustion.

It`will be seen that by disposing the coarser chips a-t the center and raising them slight- The i ly above the oor of thepbowl, a relatively free passageway for the mixture of gas and air is provided within the central part of the brick highly satisfactory, but I do' not aim to convey the impression that other forms ofgranular material may not be used..

Theoretically,- the ideal way of making up this burner would be to have the bowl 1 covered by a mass of checker work in a very thin v layer, preferably graduated from coarse checker work at the central part to fine checker work at the outside, and then to have a layer of some material, assume, for example, quartz, overlying thetop surface of the checker work and serving to direct the gases of combustion all out to the outerperiphery, but permitting freely of radiation fromfthe top surface of the same. Now the construction which I have shown, namely, the flat thin chips .of refractorymaterial, that is, broken {ire-brick, serve to perform Athis function suiiiciently well t'o direct the flow of burning gases' out along the surface of the bowl 1 so that burning occurs within the mass of broken refractory, even though it is I.very thin, and the `heat thus developed is projected off by radiation substantially normal to the surface of the granular mass. It will be seen that by the shingling effect the gases are diverted downwardly toward the surface of the bowl 1 and thereby are held more or less in contact with the same. i Y

I have tried the 'burner without the layer of granular refractory. It will burn gas, but two things are noticeably absent; first0nlya v ery small amount of radiant heat will be developed; and,` next, only a small amount 'of l gas can be burned within the bowl as compared with the amount that can be burned when the layer of loose refractory posed thereupon.

Preferably in the operation of the device,I 125 the blower is started .and the spark plug is caused to act, and thereafter the gas is admitted through the pipe 24. When combustible mixture reaches the spark plug, it will be ignited and it will burn back to substantially the edge of the cap 33.

is dis- If the amount of mixture delivered to the burner is increased, the edge of the flame reaches out further towards the periphery of the bowl 1, and if the amount 'of fuel supplied is decreased then` the flame recedes 1n thel refractory'layer towards the'cap 33,; but the size of the iame within the limits of the burner is immaterial, or substantially so for the development of radiant heat. The` amount of fuel whichcan be burned per unit of time in a burner of this character is amazing. The efiiciency of the device as a radiator of heat is very high, because of the large radiating area ascompared to the volume of gas under combustion or the volume of material which is at incandescence.

In Fig. 3 I have shown a modified form of nozzle construction. In this construction the bowl 1 is made of a plurality ofsectons, the edges of which overlap, as explained in connection with Figs. 1 and 2. This bowl, like'- Wise, has the central aperture 41 through which the mixture of gas and air is delivered under the cap member which comprises a metal cap /member 42 covered with a layer or covering 43 of lire-brick or like material. The spider 34 may be made integral with the metal cap 42, or it may be made separately.

- The spider 34 has suitable vanes which serve both to sup-port the cap and also to direct the mixture. The nozzle gap 44 is formed between two metallic surfaces, namely, the

4 viiange 45 of the cap and a companion flange 29 and the slot 35,

' combustible mixture,

until substantially the very outlet into the. Hence, in starting or 46 of a neck member 47 which forms an extension of theair passageway 16 above the vane 17 and the peripheral inlet 29 from the gas chamber 15. y l

I wish to call attention to the very small volume of mixture which can at any time exist between the slot 29 and the slot 44, in the form shown in Fi 3, or between the slot sfliown in Fig. 2.. The volume of combustible mixture is so small at any time that, even ifthe sameshould be ignited, no serious injury can be done, particularly in view of the fact tbatthe cap 33 or 40 is held in place `only by its own weight.

The velocity of the gases through this art of the pathis normally so great that com ustion does not strike back. Inaddition, mixing is carried on in such a short space that a as such, is not attained combustion space? stopping combustion underk automatic control, the 'obj ectionable explosive start or stop of the prior art is not encountered.

Tests which I have made on this burner, in conjunction with a standard and well known cast iron boiler very widely soldfor domestic heating,.known asthe Ideal boiler, manufactored bythe Americanl Radiator Company, -and designed for the combustion of solid .fuels such as coal or coke, show amazingly high efficiencies.

was approximately 45 lbs., and theweight ofI the irebrick chips 5 lbs.

thick at the center and 3% thick Due to the small mass of the chips 38, and

their being spread out in a thin layer, the

appearance of incandescence was almost immediate, especially in a ring just outside the point 37. This ring of incandescence spreads very rapidly, and thetemperature increases rapidly, until a balance is obtained between .the heat absorbed from the combustion and that radiated to the boiler. Numerous obser vations with a Leeds & Northup optical .py rometer sb ow a temperatureof approximately 3000o F., or slightly more, these observations being taken through the interstices between the chips. Since the points observable are those which radiate heat through the interstice, the temperature of the point seen is less than the majority of these surfaces, which are radiating and/or reiiecting heat back and forth between each other. It is believed that the temperature of thelower side of the chips approximates 3300 F., as there are very visible evidences of the softening-of the surfaces of these chips now being used, which are of *the brand known as Empire, which softens at that temperature. y l

It is evident that with a single layer of chips, such as were used in these tests, having the under side of such chips at such a high temperature, gives a maximum of radiation to the heat absorbing surface.

Two of these tests were run in strict accordance with the code of the American Gas Association, under the direction and supervision of two technical experts of a prominent public utility company, and with the cooperation of their laboratory in obtaining accurate determinations of the heating value, density, etc. of the gas used. f

In one of these tests,` the output of the boiler was 87.4% ofthe rating given it by the Master Steam Fitters Code of Chiago, and an' efficiency of 81.2% was obtained, based on the higher heating value of the gas. In the other test, the output of the boiler was 176.8% of the Master Steamtters Code, and aneiiiciency of 7 6.45%.was obtained. Since very little type of boiler, these eiiiciencies are truly remarkable. This is especially true when the unavoidable loss up the stack of the latent heat o f the water of formation, and the radiation to the room from is considered.

The average rate of lgas consumption in these tests varied from 259 cubic feet per hour to 385.*cubic feet value from-523v B. t. u. to 540 B. t. u. The gas pressure just outside the boiler varied convected heat absorption is possible in this i the uncovered portions of the boiler (charged asa loss in these tests),

per hour, and its heatingx..

from a minimum'of 2.05 to '3.75" of water and the air pressure from 1.55 to 3.65 of water, both being largely a function of area of passageways provided andl the quantities of each required. Later experiments with largerl pipes, etc. have burned successfully 500 cubic feet of gas per hour with the small pressures available. p

The carrying away of heat up the stack due .to excess air `was very .-little, as shown by the following analysis of the flue gases:

CO2 *13.2-* 12.0 02 `3.9 4.6 C() 0.0 0.0 Iotal 17 1 17.5

. covered.

` The sections of the bowl 1 are preferably hold by dowel pins, such 'as shown at 47 in Fig. 2 for loosely holding the parts together upon the frame ring 6. The vane member 16 is preferably formed on an increasing pitch in conical shape, and it will be observed that, in general, the cross section of the passage for the mixture of air and fuel continues to be re- Y stricted through the outlet at 35 or 44. The

lower end of the vane member 17 comprises a ring which is set in a recess in the lower` part Y of the inixer 14 and held therein by a pin 48. Instead of having the top surface of the bowl l smooth, I may provide the same with a series of sections which serve, in part, to support the chips '38.

Instead of using separate chips or granular bodies, I may form a foraminated or reticulated plate or body to be disposed upon the refractory base 3 or such formation of the upper face or portion of the base 3 maybe made as to secure the desired structure of loose or foraminated mass within which combustion may be carried on and from which heat radiation mayoccur.

I do not intend to limit the invention to the details shown or described.

1. In combination, a dished plate of refractory and insulating material2 a layer of.

relatively thin flat refractory bodles supported on the dished plate with their'ilat sides generally upwardly disposed, and a'central nozzle projecting a sheet of quick burning mixture radially into the layer of refractory bodies.-

2. In combination, a. disc of refractory material having a central aperture a supporting frame for said disc, a layer of granular refractory disposed on said disc, a nozzle supported o n said frame and registering with said aperture, said nozzle having a peripheral i outlet for discharging a combustible mixture edgewlse into said layer of granular refractory.

3. In combination, a thin bed of granular refractory, a supporting refractory bowl, and

a spark plug supported on said bowl and having its sparking terminals disposed within said bed of granular refractory. 4. InA combination, a frame com-prising a ring member having supporting means therefor, a nozzle member having inlets for gas i and air and a short discharge passageway terminating in a peripheral slit, a segmental disc of refractory material supported on said.

ring member, said disc being apertured at its 35 center and surrounding said nozzle, said nozzle having a cap member -comprising refractory material and 'a thin. layer of overlapping refractory chips disposed on said disc in register with said peripheral slit.

terial, a central stationary nozzle comprisingv a stationary cap, means for profecting a thin sheet of combustible mixture out radially 90 5. In combination, a bowl of refractory mafrom under the edge of the cap, and a layer of refractory chips on said bowl.

6. In combination, a supporting frame, a facing ofl refractory material comprising a bowl, central inlet means lfor a combustible mixture, a cap over said inlet means providing a discharge slot below the cap between its rim and the bowl, and a layer of refractory chips on said bowl overlying the edge ofthe cap. 7. In combination, a supporting frame having a refractory facing forming a bowl, and a layer of refractory chips on the surface of said bowl, said chips being of graduated litness from the central partfof the bowl to the rim thereof the top of the layer being subl stantially bowl shaped.` ,p

8. In combination, a supporting frame having a refractory facing forming a bowl, a layer of refractory chi s on the surface of said bowl, and means for ischarging substantiallyf all of a fast burning mixture from the central part of the bowl outward towards the rim through said layer of chips. y

9. In a burner, the combination of a. bowl having a central aperture, a cap covering said aperture, a layer of refractory materialv in the bowl extending from the cap to the periphery, a supportingspider between the cap and the bowl, and a gas-airmixer having a discharge port leading through the spider under said cap.

10. In a` radiant heater, a thin laye-r of pieces lof refractory material, andcentrallyW located means for projecting a blast of a combustible mixturelin the form of a sheet moving 'through and substantially along the layer of refractory material.

1l. In combination in a radiant heater, a plate of refractory material, a plurality' of refractory members inclined to the plate with their lower ends in contact therewith and their upper ends spaced above the plate, saidl members being disposed in overlapping relaxtion and defining a substantially continuous sheet of refractory material, and means for projecting a burning mixture in a sheet edgewisebetween the plate and said refractory sheet, the inclined under faces of 'the refractory members acting toI deflect the burning mixture downwardly toward the plate,and away from the upper face of the refractory sheet.

l2. In combination ina radiant heater, a plate of refractory material, a relatively thin sheet of-refractory material s aced from the plate and comprising a plura 1ty of elements disposed in overlapping relation, the plate and the sheet defining a passage therebetween for flow of a burning mixture therethrough, and means for projecting a burning mixture through said passage and along the inner face of the sheet for heating it to incandescence. A

13. In combination in a radiant heater, a thin sheet of refractory material comprising a plurality of elements disposed in overlaping relation, and means for projecting a urning mixture along one face of the sheet and -in contact therewith for heating the .sheet to incandescence, the other face ofthe sheet acting to radiate the heat therefrom.

14. A burner comprising la base of heat resisting material, a series of superim osed rel fractory elements surmounting said ase and arranged in a single layer defining one side K of a combustion space and with interst1es between adjacent elements opening directly mto said space, and means for introducing a combustible mixture between said base and said refractory elements and burning it in said interstices and said space.

15. A burner comprising a base of heat resistng material having a' central opening, a serles of superimposed refractory elements surmounting said base and arranged in a smgle layer defining one side of a combustion space vand with interstices between adjacent elements opening'directly into said space, and means arranged in said central opening for introducing a combustible mixture between said base and said refractory elements and burning it in said interstices and said space. i

In witness whereof, I hereunto subscribe my name this 16th/day of July, 1927.

ASHUR U. WETHERBEE.

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