US2174962A - Radiant - Google Patents

Description

Oct. 3, 1939. a. v. BLAYNEY RDIANT Filed Feb. 21, 1938 2 Sheets-Sheet l llll e @fr man? WA y u l Oct. 3, 1939. c. fv. BLAYNEY RADIANT Filed Feb. 2l, 1938 2 Sheets-Sheet 2 Patented Oct. 3, 1939 y UNITED STATES RADIANT Charles V. Blayney, Chicago, Iii., assignor to General Combustion Company, Chicago, Ill., a eopartnerahip comprising Charles V. Blayney and Byron A. M'

Application February 21, 1938, Serial No. 191,867

l2 Claims. (01158-7) My invention relates to combustion and includes among its objects and advantages 'an improvement in the generation and application of heat to such a heat receiving instrumentality as the bottom of a tea kettle or cooking utensil.

In the accompanying drawings:

Figure 1 is a plan view and Figure 2 a side elevation of a gas burner including a radiant according to the invention;

Figure 3 is a section on line 3-3 ofFiaure l;

Figure 4 isa side elevation of the central radi--v ant core; and l Figure 5 is a detailed sectionof the burner on line--IofFlgure 1. y

In the embodiment oi the invention selected for illustration, the mixer Il is provided with the usual air inlet openings I2 with a central bridge I4 threaded to receive the gas discharge nozzle il.. The mixer has a supporting shoulder at il 5 and a straight cylindrical neck 2l. The burner comprises the outer annulus 22 provided with iet orifices 2| inclined outwardly and other jet oriiices 26 inclinedinwardly. Upon reference to Figure 1 it will be noted that the inner oriiices 2G are more widely spaced than the outer oriiices 24.

The annulus is part of a one piece casting including the tubular bridge 2l which is provided with a central boss 3l which fits over the neck of the mixer. 'nus Joint is made snug enough to hold the burner in proper alignment, but loose enough to permit the user to -lift the burner off readily. The burner casting also includes six radial arms 32 extending outward from the bottom of the annulus 21 to support the outer support ring 34. Four equally spaced lugs 36 extending upward from the outer periphery oi the ring 34 provide effective socket means ion/holding the outer ceramic ring against lateral displacement.

' 'Ihe 'outer ceramic ring isvan annularbody hav- 40 ing a substantially cylindrical inside wall at ll s lar 48 encloses the upper portions of the grooves to accomplish this direction of thel air rising l through them. I have indicated -a slit or kerl' at 50 in Figures 1 and 2. Certain types'of refractory of the best thermal characteristics for such work, when made up in the sizes illustrated, ex-

hibit a slight liability to crack during rapid heating or cooling, and such a kerf eliminates any. danger ci' such cracking, The keri is preferably formed midway of one of the buttresses l2. This avoids interfering with the action of any ot the grooves, and the opening through the kerf is long and narrow so that itsv eccts on air circulation are negligible.

Midway of the bridge 2| I provide an upwardly pair of projecting lugs Il, holds the inner radiant 50 in position. The inner radiant is provided with grooves Il between buttresses Il generally similar to the grooves and buttresses oi the outer radiant, but on account of the smaller size of the pie there are only seven such grooves and buttresses,l and no kerf is needed. The grooves of the inner radiant face outwardly, i. e., towardl the products of combustion, whereas those of the outer radiant face outwardly. but that is away from the products of combustion.

I haveillustrated a metal shield comprising an upper band 62 and a lower band. united into a frame by risers II. two of which have'projections il bending under the shoulder 34 to hold the a snug iit on the lugs 3G, lwhich-lathe preferred construction. or one or two of the risers may be `bent in' above the shelf 3l.. The metal screen performs no material function in connection with the phenomenon of combustion, but under certain conditions of service it is desirable as a me- ,chanical protection to guard the outer radiant from mechanical injury due to blows.

lTheir'isti'umentality to be heated is preferably located above the upper level of the radiante a distance equal to about half the heightof the radiants in some such position as indicated by the dotted line'll in Figure 3.l At the iight side of Figure 3, I have indicated four different tem peratures, purely to indicate and explain the principle of action involved'. Under varying conditions actual temperatures might be materially higher or lower than-those indicated, but the principle would remain the same. Although the temperatures in the luminous portion of the individual llames issuing from the iets 24 and 28 would be much higher, it is assumed in the illustrative embodiment that after the processes of.

combustion are complete and the material issuing from the jets is also mixed with the air rising in the annular space between the radiants on either side of the annulus 22, the approximate parts in place. The lower ring N. may be made will be 2000".

By the time these gases have risen nearly to the top of the radiant, they will have delivered their sensible heat by radiation and convection to the radiants and to the cold surface at 'l0 and will be reduced to some such temperature as 1200". And

after they have issued from the annular spacebetween the radiants and are lying between the radiants and the surface 18, they will have been further cooled to some such temperature as 900. Finally close against the surface 10 (which, in the case of a tea kettle would not be materially above boiling point of water) there will be a thin layer of relatively cold gas lying in contact with the metal itself and delivering heat thereto. And the cooling action of the surface 10 will build up these relatively cold gases against its undersurface and they will eddy down in waves due to their greater density and be wiped radially outward by the iiow of the body of gases present. This indicates in a general way the temperature gradients involved in carrying heat to the surface 10 by convection.

However, the inner surface of the outer radiant and the outer surface o! the inner radiant both rise to temperatures of incandescence. Under ordinary conditions of service these surfaces vary from a dark cherry red to a light straw color. Accordingly the entire annular pocket above the annulus and between the radiants is a source of radiation which will deliver a large amount of heat direct tothe surface 10 independent of the convection action of the gases occupying the same space. On the left of Figure 3 I have drawn a series of vertical arrows 12 indicating this radiation. Directly above the center of the device, on account oi the low temperature of the boss 62, the effective radiation will be materially less as indicated by the shorter length of the arrows.

On account of the low conductivity o the material of which the radiants are made, there will be a very steep temperature dropin the wall of the outer radiant, and its outer surface, under ordinary conditions of service, never reach incandescence. But the grooves l0, the walls of which are considerably above room' temperature, warm the air in the grooves and direct upward currents of air as indicated by the arrows 14 at the right side of Figure 3. While these rising currents of aix` are probably not hot enough to add appreciably to the convection of heat to the surface 10, their presence, and especially the inward inclination with which they rise to mingle with the gases rising between the radiants, enables them to throttle or retard the radial ilow of the gases that have come up between the radiants so that the speed of movement of these main heating gases is materially retarded. Without such retardation, the main heating gases could get up above the radiants with considerably higher temperature and escape laterally from under the surface 'l0 with considerable higher temperature, which higher temperature would represent a direct loss of heat which is avoided by the action of the air currents from the grooves I0.

Under certain conditions of operation, the cool.. ness of the surface 10 and the temperatures of the various parts of the inner radiant 56 are such that some gases will pass downwardly as indicated by the arrows at 14 in the middle of Figure 3, down along the axis of the device into the boss 52. However, this represents no loss of heat, inasmuch as these relatively warm and therefore preheated gases can pass out through the weepholes 'i8 and mingle with the rising air around the jets 2t. In

2,174,962 final temperature of the products of combustionV this way I avoid the formationl of any pocket where explosion might take place and at the same time save the weight and undesirable heat conductivity that would result from making the boss 52 solid. 'Ihe withdrawal oi small amounts oi recirculated gases in this way at the center, de flects the main stream of the products of combustion radially inward and further retards its escape outwardly from under the surface 10.

The inner surface of the outer ring is tapered with the small end uppermost. In one successful design the ring is two inches high and its inside diameter is 4H" at the bottom and substantially V4 less at the top. This constriction assists .in retarding the movement of the products of combustlon.

Without'further elaboration the foregoing will so fully explain my invention that others may, by

applying knowledge current at the time of appli' cation, readily adapt the same for use under various conditions oi service.

I claim:

1, In a heating device, in combination: inner and outer radiante deiinlng an annular combustion space open at top and bottom; a burner annulus in said combustion space near the bottom thereof, said annulus lying outside the lower portion of said inner radiant, and inside the lower portion of said outer radiant; passageways in said outer' annulus for generating thermal convection currents and delivering them upwardly in general parallelism with the products of combustion, but inclined radially toward the center of the device; passageways in said inner radiant permitting a 'circulation of gases downwardly inside said radiant; a support for said inner radiant; said support having passageways through itself for the exit of the gases moving downwardly inside said inner radiant.

2. In a heating device, in combination: an annular radiant defining a combustion space open at top and bottom; a burner annulus in said combustion space near the bottom thereof; and outwardly open passageways in said radiant for generating thermal convection currents and delivering them upwardly in general parallelism with the products of combustion, whereby the lateral escape of the products of combustion is retarded.

3. In a heating device, in combination: inner and outer radiants deiinlng an annular combustion space open at top ad bottom; a burner in said combustion space near the bottom thereof; and passageways in said outer annulus for generating thermal convection currents and delivering them upwardly in general parallelism with 'the products of combustion, whereby the lateral escape of the products of combustion is retarded. 4. In a heating device, in combination: inner and cuter radiants defining an annular combus- 'tion space open at top and bottom; a burner in said combustion space near the bottom thereof; passageways in said inner radiant permitting a vertical circulation of gases downwardly inside said radiant and upwardly outside said radiant, whereby the products of combustion are drawn radially inwardlabove said inner radiant and their lateral escape is retarded.

5. In a heating device, in combination: inner and outer radiants defining an annular combustion space open at top and bottom; a burner in said combustion space near the bottom thereof; passageways in said outer annulus for generating thermal convection currents and delivering them upwardly in general parallelism with the prod- I5 we sind radially inwsrd.

3. e. nesting device, in combination: an annuler indient haring en outwardly iecing corrugated Wall; and e collar bridging the upper portion ci the ccrrugations in seid outer Wall to dene closed passages directed upwardly end radially inwerd.

ii. ln s heating device, in combination: an

I ennuler redicnt having an outwardly lacing corrugeted well; seid well corrugstions delining passages extending in e. generally upward direcy tion end or greater vertical dimensions than horizontcl dimensions; and a collar bridging the upper portion of tine eorrugations in said outer 'wall to enclose the upper portions of said passages'.

9'. A inenting device according to claim. 8 'in which said radiant and collar are` mede up of a. single piece of ceramic material,

10. In a. heating device, in combination: a central metal member apertured to permit the enit of combustible ges to i'orm c iiame; a metal cnnulus encircling said central member and spaced outwardly therefrom to leave an annular opening surrounding and adjacent to said centrol member, which annular opening constitutes an entrance for secondary air; an annular nonmetallic radiant resting' on said metal annulus and extending above and below the center of the ame from seid apertures; and spaced radial arms of metal extending outwardly from said central member below the flame to support said metal ennulud il.. A heating device according to claim 10 in which said central member, said metal annulus, end said radialarms are cast in one piece.

12 heating device according to claim 10 in Whichthe outer periphery of said metal annulus lies means projecting upwardly adjacent the outer periphery of said radiant to confine said radiant to a position substantially coaxial with said annnlus.

CHARLES V. BLAYNEY.

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