USRE19860E - heath - Google Patents

Description

Feb. 18, 1936. F. A. HEATH Re. 19,860

OIL BURNING FURNACE Original Filed Feb. 10, 1928 2 Sheets-Sheet l BY J ATTORNEY Feb. 18, 1936. H T Re. 19,860

OIL- BURNING FURNACE 4 Original Filed Feb. 10. 1928 2 Sheets-Sheet 2' leissued Feb. 18, 1936 UNITED STATES PATENT OFFICE.

on. BURNING FURNACE Forrest A. Heath, Upper Montclair, N. J.

Original No. 1,886,675, datedNovember 8, 1932, Serial No. 253,271, February 10, 1928. I tenewed March 12, 1930. Application for reissue October 25, 1934, Serial No. 750,024

35 Claims.

I My present invention is related to that set forth in my companion application Serial No. 253,270, flied February 10, 1928 now Patent No. 1,979,465, granted November 6, 1934. It concerns oil burning apparatus of the class in which metered, and more or less mixed oil and air are sprayed, preferably centrifugally above a refractory hearth that closes in the lower end of a fire box and more specifically to apparatus having the oil projecting means and the hearth organized and operating in such combination that in normal full operation as well as at starting, the flame line or region where active combustion is precipitated is localized adjacent the periphery of the hearth which thus functions as the burner. My present invention also contemplates the use in such a combination of certain features of my prior invention, disclosed and claimed in said companion application, including some of the features of the hearth, which are herein claimed only in combination with certain modifications and additions whereby my present hearth is even better adapted to improve the certainty and speed of ignition; to lessen the danger of having the ignited oil flame put out by being smothered in excess gas evolved at starting; and,

in normal full operation, to more certainly 1o calize at the periphery, the zone where active l combustion is precipitated.

One feature of said application adapted to my present invention concerns having the periphery of the hearth formed with vertical impingement surfaces of fire brick orthe like, adapted to aflord catalytic surfaces top-recipitate combustion at the periphery after the refractory material gets highly heated in normal running. One or more such impingement surfaces extend upward to or above the highest horizontal level to which the oil can be projected by the projecting apparatus, so that most of the unatomized drops of the projected oil impinge thereon. In lmy prior application, this'impact and ignition wall j is closely adjacent the wall ofthe fire box and operates like a burner from which the flame rises in contact with said fire box wall. My present invention contemplates rearrangements and additions whereby this somewhat primitive burner is evolved into a more definite type of burner adapted to discharge flame more directly on the blast of flame and combustible mixture into conwall to be heated. One feautre is spacing this tact with the wall of the furnace. In practice, the combustible draft from the rotary projector is deflected upward by the impact and ignition wall so that it shows a tendency to curl back away from the wall toward the center portions of the fire box, but it may be readily understood that when such upward draft blast passes the upper margin of a wall having a rear space, the

blast tends to draw a vacuum in said space, there- 'faces become white hot, promoting perfect, combustion, even though the flame and draft there from pass immediately into contact. with the relatively cold walls of the water leg of the boiler. While the vacuum and eddy producing effect of the space behind the impact wall is inherent, my

present invention includes the further feature of having the spaced apart cooperating refractory wall, forwardly sloping and provided with rearwardly directed reticulations through which the flame may be definitely directed upon the wall to be heated. The space adjacent thefront of this cooperating refractory wall, in reverberatory relation to the rear surface of the impact wall becomes a hot gas generating region, and if the rear wall is forwardly sloping, the reticulations will cause the rear face to function like a multiple gas jet burner, the jets whereof are directed against thewater leg to be heated. In the latter particular it is analogous to a Welsbach mantie when over-supplied with gas and air mixture. In the form shown, the rear wall of this reverberatory space extends forward far enough to overhang the vertical impact surface, tending to positively deflect the flame and gas mixture rearwardly behind the impact wall, in addition to the above described induction or vacuum effect whereby the flame and gases naturally tend to curl and eddy behind the wall.

- As in my companion case, I may use one or more collecting gutters or grooves adjacent the base of the impingement surface, said gutter or gutters being of cross section sufficient to hold all of the unignited oil that can collect during the starting period. This peripheral gutter may be a pronounced groove, of depth dependent on the area of the impingement surface draining thereto, so that the exposed top surface 'of the oil collected therein is of relatively 'small area.

Another feature cooperating well with the collecting gutter, but which may be suflicient in itself, is to provide for an out drainage of the hearth dow/nward from the oil projector to the periphery. "Preferably, the upper surface of, the hearth is sloped so that it will be close to but out of range of the trajectory of the lowest part of the projected oil. Where such down'slope hearth is used, it forms a collecting annulus or gutter where it meets the base of the vertical-or upwardly extending surface of a peripheral impact wall. In the present case, the down .slopehearth drains into such acollecting annulus adjacent a very low vertical surface, the main impact wall and its gutter being further on toward the periphery. It is just as welLor even better tohave the drainage from the hearth into a gutter. In either case, the down slope plus the gutter mutually cooperate to produce the best results, the down slopetending to keep the hearth free from impingement of unignited oil and facilitating outward drainage of any that does impinge, while the gutter tends to minimize the exposed surface of the oil collected therein.

' As explained in my companion application, this makes it possible to start with the oil projector projecting only the amount of oil necessary for normal and yet accumulate at the periphery where it is to be ignited, an ample supply -of oil, in evenless time than would be possible by an over-supply of oil projected upon the usual up-slope or horizontal hearth which does not have any peripheral gutter. Thus the oil is conhearth and burner, fire boa wa r'l a; I Figure la is'an enlargedsectional detail showinggoreclearlyandfullythefananddraft arrangements of the burner head Figure 2 is a plan view of the burner; Figures 3 and 4 are enlarged elevations of the refractory burner structural elements; and

Flgure5isa'sectionon the line 5-,Figure4. '5 Thefurnaeetobeheatedisshowninl igure l as including a wall creasing l, closing in a space and supports the furnace which may be of any'desired construction, the essential parts shown in {affording an inter-space 4 for An annular ledge I supports a hearth pan 8 'stiflened by radial This supports .a refractory hearth I which projects an air and oil projector conventionally indicated at A.

- hearth is formed at its periphery with th vertical fuel impingement andignition wall 8 having at the base thereof an oil collectinggutter,'in this case a groove I the depth of which is about equal to, its width,

' the present case, th' hearth elements are set to that there a a slightly P jecting vertical Figure lis'a vertical sectional view of the' beingthewalllclosingintheflrebox.

to be heated or boiled, as the surface ill just inside of and parallel with the gutter 9 which is at thefoot of the main impingement' and ignition wall 8. When so set, as

and when used in combination with the outwardly down sloping hearth, any drainage from the hearth will beto the annular collecting space Illa at the foot of this wall. It will be understood,

however, that in many cases the rim of the gut-.

ter 9 will 'be set flush with the uppersurface of the hearth.

- it sometimes is, on hearths of small diameter,

Ignition torches II, II are set in position to F discharge ignition flame across the gutter 9 and against the ignition wall 8, and if there is a smaller wall III- as shown, part of the ila'me will play upon this wall also.

, Various examples of oil and air projectors suitable for my purpose are now well known. One is the oil projector invented by Homer A. Tiffany,

1' r which application for letters patent has been or is about to be made, and another is set forth in my application Serial No. 47,709, filed August 3rd, 1925, which has resulted in Patent No. 1,707,474, issued April 2, 1929. The former is the one conventionally indicatedv herein. I

The oil is centrifugall'y discharged in an ex tremely the spray or vapor through nozzles l2,

supplied through a head ll mounted on vertical creating a powerful draft below the trajectory of the oil as suggested by the arrow 2. as shown in Figures 1 and la, there are ten or a dozen fan blades I! carried by under face of the head i3. These constitute a large volume fan tending to create a vacuum in the interior space a. The four nozzles l2 constitute anothersfan creating suction at e, and through annular passage d this suction takes eflect in the same space that the. fan It draws from The air inlet to this space a is through aslot b communicating with the ash pit. cross section of this slot may be adjustab decreased orincreased by vertical slide In operation, 011 is supplied to the trough e through a suitable interior nomle notshown. Centrifugal force causes a film of this oil from trough e to creep up the walls and ultimately to be w n 08 as a fine spray proiected from the rear 1 ps of the four nozzles If. Centrifugal force also causes a relatively small volume of air .to be, projected through these nozzles I! while amuch larger volume of air is being projected by the fan blades IS. The nomles project sub- .stantially above the plane of the top plate it of the rotor; Consequently, said plate, together with the upwardly projecting surfacesof the nozzle, constitute in effect a third fan whereby hot products of combustion are projected in the same horizontal plane with the spray. The projected products of combustion and the air enveloping the much less than, that of the annulus through which blades l5 discharge.

fractory impact surfaces are at high heat, the

combustion at the periphery is substantially perfect. The oil and air supplies to the burner, as also the means for metering the same, form no part of my present invention and are not shown. Similarly, the means for controlling supply of gas to the ignition torches ll may be of any known or usual construction and are not shown. The important features are that the ignition torch nozzles H are located inside the circumference of the collecting groove and the flame therefrom impinges along the ignition wall, preferably in the same direction that.the.rotary head tends to rotate the body of air or gas within the fire box.

I have discovered by many experiments that an outward down slope for the hearth of approximately one-half inch to the foot is sufficient *tion.

to keep the upper surface below the trajectory of the oil, even when the diameter of the fire box is a maximum. As a specific illustration of preferred construction, I may note that an eightinch rotary head l2, l3, may be utilized for fire boxes of widely varying diameter simply by varying the metering of the oil and gas, a uniform running speed of, say, 1,700 revolutions per minute being maintained for all sizes of furnaces and all degrees of heat. Where such a head is used in a fire box having a hearth only 24 inches in diameter, the oil only has to be thrown 8 inches. In such a case, a slight down slope to the hearth is desirable, although the distance is so short that the oil will certainly clear the hearth, regardless of whether the upper surface of the hearth is horizontal or is slightly sloping in either direc- For such small diameters, the collecting groove alone may be sufficient without the slope. With greater diameters, the outward down slrpe is progressively of greater importance, but for all sizes of hearth up to say, 78 inches in diameter. the standard outward down slope of one-half inch to the foot is sufficient.

So far as concerns the main impact surface or surfaces and the gutter, it will be recognized that they correspond to similar parts in my companion application, but as above described their functioning after they get hot, in full normal operation, is combined with and modified by additional parts and features of construction whereby the simple wall and groove burner becomes more a gasifying and mixing region furnishing gas to and through other elements which have a more characteristic burner function.

structure, is built up of relatively short molded sections of fire brick or other refractory catalytic material. As the cross section is substantially uniform except at one point to be mentioned hereafter, these sections may be madeas standard desired diameter or shape of furnace. In the form illustrated in Figure 2, the fire box is square Thus the composite draft pro- L molded units which may be assembled to flt any I and similar units in varying lengths are sawed or otherwise formed to fit as at a, b', c, d, etc. As shown on Sheet 2 of the drawings, the units preferably comprise a base member 9a., affording the gutter 9 and affording also a support for an integral upright element to. In the rear of this is a relatively small space or cavity arranged so as to be vacuumized by the draft deflected upward by impinging on the front wall of said element, whereby in normal operation the flame and combustible mixture tends to curl and eddy backward into said space, as above described. In the form shown, the rear face 8b slopes downward at a relatively steep angle to a flat surface 80 and has integral therewith upstanding ribs 8d, affording a support surface 8e, preferably parallel with 8b, and a ledge or stop, 81'.

In this form, the cooperating reverberatory surface is afforded by utilizing the support surface as a spacer and support for a super-structure including a refractory burner slab l8, sloping upward and projecting over the wall 8 a considerable distance so that its free edge Ila is vertically be- .yond the gutter 9. This slab has burner passagesv or reticulations I817.

The relative areas of the surfaces, as well as the area and angle of the overhang l8a admits of considerable variation, but the object is first to intercept all of the unatomized drops upon the refractory faces presented toward the center of the hearth and while most of it is preferably received upon the surface 8 and drains directly into the gutter 8, it is evident that scattering drops may be intercepted by the burner plate II and if the hearth projects as at Ill, some drops may fall on this vertical surface. Drops striking above the surface 8 will naturally drain or be blown by the air draft rearward to the space behind the burner structure. a For this reason, I prefer to have the area surface 8}, Figure 5, spaced slightly apart from the fire box wall 2. Any 011 draining to this pocket will be practically out of the field of operations during the starting period, but after the apparatus is in full operation, this oil will be volatilized and burned so that no great excess accumulates. In order to provide a path of escape for any such excess I arrange a slot-like passage 8x, whereby this space drains down the surface 811 into the gutter 9 in front of the ignition surface 8.

Another factor controlling the proportions of the parts, particularly the angle and overhang of the burner plate at Mia. and the height of the supports Be is to have the horizontally discharged blast from the projector pocketed and deflected so that it will be discharged partly through the burner retioulations lb, and partly downward along the surface 8b, directly to the fire box wall 2.

These things will be further explained from theoperation of the apparatus which may be described as follows:

The usual controls are employed whereby power is supplied to rotate thehead It to deliver a predetermined metered supply of oil along the lines 1:, u and air or air and hot gas, as indicated by the arrow 2, the oil projected against ignition wall 8 collecting in groove 9. Some of it may be projected under or through the slab II, but this drains rearwardly as described above. The maximum exposed surface of oil is therefore practically limitedt'o the area of the exposed burner surfaces plus the upper surface area of the oil in groove 9. All of the oil being concentrated in the ignition region, the ignitiomtorches quickly,

ignite the on around the entire periphery,but anyincreasedoilsurface thatsuchignltion brings 'into play, is above and beyond the'aone ofthe ignition airface and gutter, there being little, if any, oil on the upper surfaces of the hearth. consequently the igniting operation is quick and uniformly progressive until the entire periphery flames. Any 011 on the overhang or undersurface of burner plate It is in the best possible position to intercept and be vaporized by the growing blaze from below.

It will be noted that during the ignition period,

the combustible blast mixture is deflected through the burner and cleared of excess oil drops carried thereby, thus tending to correct the natural overrichness' of the mixture at this stage when so much oil is' being evaporated from the wet surfaces. The burner plate It and particularly theoverhang portion thereof, being thin, quickly become incandescent, as also the thin'upper tips and edges of the projecting supports (1.; Later on, all of the surfaces'become hot enough so thatin normal running all oil droplets are vaporized immediately upon impact with the burner surfaces.

Another very important function of the burner plate is that of a homogenizing mixer. The blast from the projector nozzles is more or less flnelyy/ally dlscha subdivided or atomized spray. is.deliveredbelow-the spray by the fan and naturallytends to cross the path of *the spray and forms with it a combustible blast that carries on its upper surface an' admixture of burned out gas rich in carbon dioxide. This three-fold mixture projected against the burner is thoroughly bailed and homogenized as part of it is through the reticuiaticns of the burner plate part is deflected downward-and rearward under the plate. The advantage of such a homogeneous mixture is well known and the special advantage of the carbon dioxide diluent is also well known as conducive to a voluminous flame, of less intensity but much greater heating eifect as concerns the fire wall 2.- In normal full operation, my present invention makes it possible to u out down the air to just the amount needed for complete combustion with the result that the flame may be almost invisible, like the blue part of the flame froma well regulated Bunsen burner.

. An important feature is that'this flame is directed through the burner plate and downward under the plate directly 'into contact with the wall 2, and starts its upward licking p we; undisturbed by the blast from the fan.

The. ignition torch may and frequently does ceasetobeflamingwhen the oilisbeingrapidly vaporized and burned in close proximity thereto.

There is no disadvantage because the torch gas isburned along with the oil vapor so long as norrnal operation continues. The remarkable point is that when the oil projector is turned off and the oil flame dies down, it naturally shrinks down behind the ignition wall to the'surplus ofl there collected and then follows oilthrough the slot 0: intothe groove, thus relighting the ignition torch before itself becoming extinguished. Or if the ignition torch is intermittently operated by a pilot light proiecting upward in the groove 1, as in my canpanion application, it will be the pilot-that is relighted in this-way.

while I have shown the. flre box as-being it is to be understoodvthat in practice they are often oblong or circular. In such cases the peripheral burner preferably follows the fire boximpact surfaces. I

P the projected on and deflect the draft upward, an:

wall inthe relation indicated incroa section in Figure 1, although it is desirable to have it cut across the extreme angles of the corners as shown. a h

I claim: lsAp'paratus of the class described, including a furnace, 'ahearth closing in the bottom thereof, and a centrifugal projector radially discharging a composite draft of air adjacent the upper surface of the hearth and oil above the air, said projector and hearth being designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; and, extending along said peripheral zone. a homogenizing burner of refractory material adapted to intercept the path of the projected oil. an oil collecting gutter in drainagerelation to said homogenizing burner, a rear oil rain: a composite draft of air adjacent the per surface of the hearth and on above thfljfi-ll', and a homogenizing gasifying burner of.

refractory material adjacent the upright furnace walls all designed and operating to maintain the bottom thereof, a centrifugal projector radicombustion in a peripheral zone of impact and disturbance of the projected composite draft; said burner being formed with wall elements having upwardly nding, inwardly presented to intercept the path of I oil collecting gutter in drainage-relation to said impact -surfaces,-said burner having also transverse es and an overhanging deflector eledeflect the upward draft outinent arranged ward against sai furnace walls.

3. Apparatus'of the class described, including I a furnace having an upright wall, a hearth closing in the bottom thereof, a, centrifugal projector radially 4 a composite draft of air adjacent the upper surface of the hearth and oil above the air, and a homogenizing gas'ifying burner of refractory material adjacent said upright wall, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; saidburner being formed with. wall elements having-upwardly extending inwardly presentdd'im'pact surfaces adapted to intercept the path of the projected oil and deflect the draft upward, a rear oil collecting gutter behind said burner, and a drainage passage draining from said rear gutter to the front of said wall.

1 '4. Apparatus hr the dissent-scribed, including" a furnace having upright walls, a hearth closing in the bottom thereof, a centrifugal projector radially discharging a composite draftof 'air adjacent the upper surface of the hearth and oil above the air, and a homogenizing gasifying" burner of refractory material adjacent the upi right furnace walls, all designed and operating to maintain combustion in a peripheral zone of im-:

pact and disturbance of the projected composite;

draft; said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil and deflect the draft in the bottom thereof, a centrifugal projector radially discharging a composite draft of air adjacent the upper surface of the hearth and oil above the air, and a homogenizing gasifying burner of refractory material adjacent said upright wall, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil and deflect the draft upward, said burner having also a burner plate having reticulations through which the draft flows.

6. Apparatus of the class described, including a flre box, a refractory hearth structure including a hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil sprayer and an air projector discharging horizontally below the oil sprayer, above the hearth, said hearth having a substantially unobstructed upper surface lying below the level of normal projection of the oil spray, designed and operating to initiate combustion adjacent the periphery of the hearth, said hearth structure having adjacent the periphery an upwardly extending refractory ignition wall, adepression at the base of said wall for collecting oil splashing or draining downward from the front face thereof and drainage 'means formed in the wall whereby oil projected beyond the impact face thereof may drain to said front oil collecting space. v

7. Apparatus of the class described, including a furnace having upright walls, a hearth closing in'the bottom thereof, a centrifugal projector radially discharging air and oil over' the upper surface of the hearth and creating a draft that approaches said upright walls, and a homogenizing gasifying burner adjacent the upright furnace walls, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected air and oil; said burner being formed with wall elements having inwardly presented impact surfaces shaped and disposed to. intersect the path of the projected oil and deflect the draft upward, said burner having also a deflector element arranged to deilect the draft against said furnace walls.

8. Apparatus of the class described, including a furnace having upright walls, a hearth closing in the bottom thereof, a centrifugal projector radially discharging a composite draft of airadjacent the upper surface of the hearth and oil above the air, and a homogenizing gasifying burner of refractory material adjacent the upright furnace walls, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil and deflect the draft upward,

jacent the upper surface of the hearth and oil above the air, and a homogenizing gasifying burner of refractory material adjacent the upright furnace walls, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil and deflect the draft upward, said burner having also an upper overabove the air, and a homogenizing gasifying burnerof refractory/material acfiacent the up right furnace walls, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected, composite draft said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil and deflect the draft upward, said burner having also an outwardly and downwardly sloping burner plate arranged to deflect the upward draft outward against said furnace walls.v

11. Apparatus of the class described, including a furnace having upright walls, a hearth closing in the bottomthereof, a centrifugal projector radially discharging a composite draft of air adjacent the upper surface of the hearth and oil above the air, and a homogenizing gasifying burner of refractory material adjacent the upright furnace walls, all designed and operating to maintain combustion in a peripheral zone of impact and disturbance of the projected composite draft; said burner being formed with wall elements having upwardly extending, inwardly presented impact surfaces adapted to intercept the path of the projected oil anddeflect the draft upward, said burner having also passages for permitting outward flow of the draft, and a burner plate supported above said impact surfaces by spacing elements to afford transverse passages arranged to direct the upward draft outward against said furnace walls.

12. Apparatus of the class described, including a fire box, a. refractory hearth structure including a hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil sprayer and an air projector discharging horizontally below the oil sprayer, above the hearth, said hearth having a substantially unobstructed .upper surface lying below the level of normal projection of the oil spray, all designed and operating to maintain combustion adjacent the periphery of the hearth, said hearth structure having adjacent the periphery an upwardly extending refractory ignition wall and above said wall a plate element and supports therefor, adapted to intercept oil projected by the oil sprayer.

13. Apparatus of the class described, including a fire box, a refractory hearth structure including a hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil sprayer and an air projector discharging horizontally below the oil sprayer, above the hearth, said hearth having a substantially unobstructed upper surface lying below the level of normal projection of tain combustion adjacent the periphery of the hearth, said hearth structure adjacent the periphery an upwardly extending refractory ignition wall and above said wall a plate element and supports therefor, adapted to intercept oil projected by the oil sprayer, and said wall having itsupper surface draining outward toward the periphery.

14. Apparatus of the class described; including a flre box having upright walls, a refractory hearth structure including a hearthclosing in the bottom thereof and a rotary-head comprising a centrifugal oil and air projector discharging above thehearth,:said hearth having a substantially unobstructed upper surface lying below the level of normal projection of the discharged oil, said hearth structure having adjacent the periphery a refractory wall with spaced-apart projections extending upwardly above said level, said refractory wall being arranged to afford impact surfaces in the path of said spray and surfaces presented rearwardly adjacent said upright walls of the fire box.

15. Apparatus of the class described, including a fire box having upright walls, a refractory.

hearth structure including a hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil and air projector discharging above the hearth, said hearth'having a substantialLv unobstructed upper surface lying below the level of normal projection of the discharged oil, said hearth structure having adjacent the periphery an upwardly extending refractory impact wall, a rearwardly extending face of which is adjacent but spaced apart from said the box walls, in combination with a member afl'ording supplemental refractory surfaces in reverberatory relation to said rearwardly extend-- ing face of said impact wall and affording spaced apart paths for escape of flame and combustible mixture from the reverberatory space into-contact with said upright walls of the flre box.

16. Apparatus of the class described, including a flre box having upright walls, a refractory hearth closing in the bottom thereof and arotary head comprising a centrifugal oil and air projector discharging oil and air draft over the hearth, alldesigned and operated to maintain combustion adjacent the periphery of the hearth, I in combination with a refractory wall adjacent the peripheryof the hearth, said wall including a face for impact of the discharged oil and upward deflection of the draft, and another face which extends toward said fire box walls, and a cooperating member affording supplemental refractory surfaces above and in reverberai'ory relation to the latter face of said impact wall and formed with spaced-apart passages for through flow of flame and combustible mixture from the reverberatory space outward and upward toward said walls of the fire box.

17. Apparatus of the class described, including a flre box having upright walls, a refractory hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil and air projector discharging ofl and air draft over the hearth, all designed and operated to maintain combustion adjacent the periphery of the hearth, in combination with a refractory wall adjacent the periphery of the hearth, said wall including 7 a lower impact portion or element adapted to dewardly inclined deflecting surfaces and formed and arranged to'aifordspaced-apart paths for L rearward and upward escape of flame and combustible mixture toward said upright walls of said flre box.

18. Apparatus of the class described, including a flre box, a refractory hearth structure including a hearth closing in the bottom thereof and a rotary head comprising a centrifugal oil and air projector discharging above the hearth. said projector being of the high speed type and said hearth having a substantially unobstructed upper surface lying below the level of normal projection of the discharged oil, said hearth structure having adjacent the periphery refractory elements presenting upwardly and inwardly inclined surfaces and formed with passages for outward and upward through flow of flame and combustible mixture.

19. Apparatus of the class described, including a fire box having upright walls, a hearth closing in the bottom thereof and a rotary head comprising and air' draft over the hearth, all designed and operated to maintain combustion adjacent the periphery of the hearth, in combination with a burner structure adjacent the periphery of the hearth, in the path ofthe discharged oil and air draft, said structure including spaced-apart surfaces in reverberatory proximity and formed and arranged to afford paths for escape of flame and combustible mixture toward said upright walls of said flre box. 4

20. A flame concentrator and director of the character described, including a grill having a flame-directing aperture, a deflecting wall extending upwardly toward said aperture, a deflecting surface in front of said wall adapted to deflect an impinging draft upwardly intoa draft passing above said deflecting surface toward said deflecting wall, and a mixing valley intermediate said deflecting wall and deflecting surface.

21. A flame concentrator and director of the character described, including a grill .having a flame-directing aperture, a deflecting wall extending upwardly toward said aperture, a deflecting surface in front of said'wall adapted to deflect an impinging draft upwardly into a draft passing above said deflecting surface toward said deflecting wall, and a vertical deflecting surface, extending transversely of said deflecting wall, intersurface in front of said wall adapted to deflect an. impinging draft upwardly into a draft passing above said deflecting surface toward said deflecting wallpa mixing valley intermediate said deflecting wall and deflecting surface, and a vertical deflecting surface, extending transversely of said deflecting wall, intermediate said wall and aperture. 23. In a flre box for oil burners of the character described, in combination," a hearth, a grill support disposed on the hearth adjacent its periphery, and grill members adapted to be disposed and supported in any selected places on the grill'support, whereby the spacing of the grill members from each other may be varied, said grill membershaving apertured portions disposed above the surface of the hearth when the grill members are disposed on the grill support.

24:. In a. flre box for oil burners of the character described in combination, a substantially annular hearth, and flame deflecting and con-' centrating grill members disposed on the hearth adjacent its periphery, said'grill members having apertured portions inclining upwardly toward the center of the hearth and spaced vertical supporting walls or flanges beneath said apertured portions directed approximately endwise toward the center of the hearth. 10

25. In a fire box for oil burners of the char acter described, in combination, a substantially annular hearth, flame deflecting and concentrating grill members disposed on the hearth adjacent its periphery, said grill members having apertured portions inclining upwardly toward the center of the hearth and spaced flat vertical supporting walls or flanges beneath said apertured portions directed approximately endwise toward the center of the hearth, and an approximately annular grill support disposed on the hearth, said grill members being supported thereon.

26. In a fire box for oil burners of the character described, in combination, a substantially annular hearth, flame deflecting and concentratlng grill members disposed on the hearth adjacent support comprising supporting units having deflecting surfaces facing toward the center of the hearth and adapted to deflect an impinging draft upwardly to andthrough the aperturesof said grill-members.

' 2'7. A fire box construction for oil burning fur-. naces of those types which are provided with centrifugally-acting'distributing heads for discharging fuel droplets substantially radially, including a hearth extending around and outwardly from said distributing head and including an upstanding peripheral portion having an inner surface which intersects the path of the discharged fuel droplets at substantially right angles, and an inwardly upwardly inclined portionoverhanging said inner surface. 7

28. In a liquid fuel burning apparatus, in combination with a combustion chamber having a hearth and a wall to be heated and afuel impact member set upon the hearth adjacent said wall, means for projecting fuel and air toward said impact member at relatively high velocity, ignition means adjacent said impact member in the general path of fuel and air projection whereby a combustion zone is formed adjacent said wall, and a perforated structuremounted above said impact member between the projecting means and said wall, the perforations of said structure being arranged in the general path of fuel and air projection and discharging toward said wall, whereby the flame in the combustion zone is concentrated upon the wall in the vicinity of said perforated structure.

29. In a liquid fuel burning apparatus, in combination with a combustion chamber-having a hearth and a wall to be heated, means for projecting fuel toward said wall, means for supplying a blast of air at relatively high velocity for admixture with said fuel to support combustion adjacent said wall, and means in the chamber for concentrating the heat of. combustion upon said wall, said means comprising a device consisting of a base structure and disposed adjacent the wall with one side forming an upright impact surface facing the air blast, said device consisting also of a superstructure providing transverse passages or openings through which fuel and air may pass toward the wall, whereby the flame of combustion is shorter than would be produced by the high velocity air blast in the absence of said device. I

30. A fire box construction for oil burning furnaces of those types which are provided with centrifugally-acting distributing heads for flinging fuel droplets outwardly, including "a hearth extending around said distributing head and outwardly therefrom, and including an upstanding portion having an inner surface which intersects wall, means for causing air to intersect the fuel stream adjacent said wall, a member providing a fuel impingement and mixing wall having a surface spaced inwardly from said "chamber wall in the direction of said fuel distributing means, and a flame-controlling structure overhanging said impingement surface and extending past the latter toward said upright wall.

32. In a liquid fuel burning apparatus, in com-- bination with a combustion chamber having a. hearth structure including? a hearth and a wall to be heated, means for projecting fuel and air toward said wall at relatively high velocity, ignition means adjacent saidwall in the general path of fuel and air projection whereby a combustion zone is formed adjacent said wall, said hearth structure further including means projecting upwardlyas a vertical continuation of the hearth and formi g a. fuel impingement surface adjacent said comb tion zone in spaced relation to the said chamber wall, and means disposed between the upper 'part of said impingement surface and said wall to spread and shorten the flame produced in said combustion zone.

33. In a liquid fuel burning apparatus emboth'ing a combustion chamber having a hearth and a heat absorbing wall and also embodying means for passing liquid fuel and air substantially horizontally through a portion of the combustion chamber at relatively high velocity over the hearth of said chamber toward the heat absorbing wall of said chamber, means forming an impingement surface spaced inwardly from said wall in the path of the liquid fuel and air, means signed to reach high temperature in operation,

means for throwing liquid fuel substantially horizontally toward said impingement surface to homogenize and gasify said fuel, means for sweeping air for combustion against said surface at high velocity to thoroughly carburet the homogenized fuel, means for igniting the combustible facedesig'ned to reach high temperature in operapingement surtion, said means being horizontally from said upright wall to form therewith achamber,

horizontally toward said impingement surface to homogenize and easily the fuel, means for sweepmeans for discharging liquid fuel substantially ing air for combustion toward said surface at high velocity to thoroughly carburet the homogenized fuel, means for igniting the combined fuel and air, and'bailiing means disposed above said impingement surface and projecting into the upper part of the last-mentioned chamber, said baming means constructed to direct part of the ignited mixture downwardly into said last-mentioned chamber.

FORREST A. HEATH.

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