US1773173A - Burner - Google Patents

Description

Aug. I9-, 1930.

BURNER A. s. 13E/Reclamy 1,773,173

File'd Dec. 1;. 1924 3 Sheets-'Sheet Z5 K" 33 'gig 7 s# of fnxfem ,45 AM'SUA f @Eff 1 Mgg;

Patented Aug. 19, 1930 UNITED STATES PATENT OFFICE BURNER Application iiled December 1, 1924. Serial No. 753,244.

This invention relates to a burner for use in a furnace burning liquid fuel, and more particularly to a compact and yecient fuel atomizer, that will operate with very small quantities of liquid fuel, in a quiet, cleanly, efficient and economical manner, in which the fue] is easily ignited under all temperature conditions, and which will require little attention, and be capable of long and continuous service.

One object of the invention is to provide a fuel atomizer unit which may be made quite small, and is capable of operating' continuous ly and efficiently on verysmall quantities of fuel. A plurality of these atomizers may be used in battery formation to heat the same furnace, whereby only one or more of these units may be used as conditions may require, the atomizers in use being operated at full efficiency.v rlhis atomizer'will handle a wide range of fuels without adjustment, and will effectively atomize quite heavy liquids in spite of the factV that the quantity used is very small. Fuel atomized by this device may be -easily and instantly ignited by a match, hot wire, or equivalent means, without the use of a primer or auxiliary heater of any kind. The parts of the atomizer are so designed, andthe materials used are so selected, that'the atomizer will automatically accommodatethe expansion of the parts due to temperature changes without affecting the adjustment. The atomizer is so designed that the liquid and the air may be supplied to the atomizer at the same pressure, and only a very low pressure is required.` The atomizei1 will not carbonize, or choke up,fand there will be no dribbling of liquid fuel at the discharge ports.

The above and other objects and advantages of this invention, will be apparent Afrom the following detailed description'of one approved form of apparatus involving the features of this invention.

In the accompanying drawings: l

Fig. 1 is a longitudinal vertical section through thenassembled furnace, this view being taken substantially on the line 1-71 of Fig.l 2. Y

Fig. 2 is an elevation looking from the left at Fig. 1, and on a somewhat larger scale.

Fig?) is a sectional view through the cones on an enlarged scale, the view being taken substantially on the line 3-3 of Fig. 1.

Fig. 4 is a longitudinal vertical central section through the atomizer, this view showing a unit adapted for use in the heating plant ouf a steam automobile in substantially full size. v

Fig. 5 is a similar view, on a greatly enlarged scale, through the discharge end of the atomizer.

Fig. 6 is a transverse section taken substantially on the line 6-6 of Fig. 5.

Figs. 7 and 8 are perspective views, partly` in central longitudinal section, through the two portions of the inner liquid nozzle.

Fig. 9 is a similar view of the nut for holding this inner nozzle in place within the atomizer casing.

The improved atomizer shown in Figs. 4 to 9 inclusive, will be first described.

In this connection it should first benoted that this atomizer may be made in a wide variety of sizes according to the use for which it is designed, but it iscapable of being made quite small, Fig. 4 showing one of the devices in 'substantially full size. The parts as shown. in Figs. 5 to 9 are considerably enlarged, to facilitate the disclosure and explanation of the construction and operation. The main block or casing 1 of the atomizer may be mounted on any suitable support such as angle bar 2, for example by means of a screw bolt 3 extending through a portion of support 2 into the body of block 1. The caslng 1 has a tubular externally threaded ex-` tension 4 on its forward end, and a cylindrii cal passage 5 extends centrally through this tubular portion 4 andcompletely through the casing` 1. The outer end of extension 4 is internally beveled as at 6. From a point lsubstantially midway of the block 1, and extending through Vthe rear face of the block, passage 5 is enlarged as indicated at 7. The vinner connecting walls 8 between the smaller and larger portions of passage 5 are beveled or have a spherical contour fora purpose hereinafter described. The greater portion of enlarged passage 7 is internally screwthreaded as at 9. hpe sections 10 and 11, screwed into the block 1, deliver air and liquid res ctively through the atomizer. The air is elivered through internal passage 12 into passage 5, and the liquid is delivered from ipe 112 through1 initidnal passagel into the ar er npl'lssage 71 A Msiflaller block or housing 14 ias a rear cylindrical portion 15 adapted to fit accurately withinthe outer endof as .sage 5, and an enlarged collar lprovi ed with a beveled face adapted to bear againstAV the internally beveled end 6 of extenslon 4. A collar 17, which screws on to the outer surface of extension 4, has an inwardly projectin flange 1'8 adapted to bear againstthe outer eveled surface 19 of the collar 16, and hold," housing 14' firmly in position Within the naar end af tubular extension 4. A

cylindrical passage,` 20T extends centrally t 'ugh the'greaterjportion of housing 14.

this assage terminates in a forward coniportion 21 converging to meet the inner endlo discharge port 22, positioned centrally in the outer end of housing 14, which serves asthe dischargennozzle for the fuel and air mixture. The outer en'd 23 of nozzle 14 is cutnoi sheer and per endicular with the discharge port 22,v andt e outer circumferential edge 24 of port 22 is made as clean and sharp as oasible, for reasons hereinafter described.

he inner liquid or Yfuelnozzle is formed l of two, sections, the forward sectionf25 being fia d fcilitating boring operations. Itis shown'separatel in Fig, 7, and the rear section 26'being s own separately in Fig. 8.

VThe threaded'extension 27 at the rear of member 25, screws into the internall threaded portion 28 at theforward end o member 2: When thus assembled the two sections essential that this passage 29 be suilitntly large to rovide a free and unobp strncted passage or the liquid fuel, and that thehdischarge port;` BUV be relatively quite so thata very fine stream of the liquid under' high velocity 'will be discharged .therefrein.` Thatfportion 32 of member 26 which Yis positioned within passage 5. and the lar er and' 33 ofmember 25, are apprecialy in greatest diameter than the interior of passage 5; so that a free annular j airpassage 34 will remain around the mem- Y fflie. centralportion 35 of member 25 same diameter," or only slightly smalllsb,

er than, the passage 20 in nozzle member 14, so that this portion 35 will fit snugly within the rear end portion of passage 20. The forward portion of nozzle member 25 has a conical formation, tapering gradually from the cylindrical portion 35 to the small tip end 31. This provides an annular air passage 37 between the conical portion 36 and the walls of passage 20, which has a cross sectional area increasinV from practically nothing adjacent the cylindrical portion 35 to a maximum area surrounding the tip 31 where this annular air passage 37 merges into the low pressure combining chamber 33 within housing 14. As previousl Y stated, this chamber 38 tapers outwardly with a gradually decreasing area as at 21 until it merges with the discharge port 22 in the outcr end of the atomizer nozzle'14. of small slots 39, here shown as 4 in number, are formed in the cylindrical portion 350i the nozzle member 25, to permit the air in passage 34 to flow into the annular expanding passage 37 surrounding the conical tip of the liquid nozzle. These passages 39 are preferably quite small, in the size of atomizer here shown preferably being not over .005

of an inch in depth. The rear portion 40 of member 26 is enlarged to more nearly the diameter of passage 7 in which this portion of the nozzle member is located, and the wall 41 connecting this enlarged portion 4() with the cylindrical portion 32 is beveled or has a spherical contour to correspond with the wall 8 in the casing 1.

When the atomizer is being assembled, the outer nozzle` housing 14 is first inserted within the end of extension 4 of the casing 1, and is secured in place by means of the screw collar 17. The two sections 25 and 26 of the inner liquid nozzle are then assembled and inserted through the rear end of passage 7 until cylindrical portion 35 has slipped into the rear end of passage 20 in housing 14, and the two beveled or spherical faces S and 41 are in contact. The inner nozzle is forced into place, and held in place by the nut 42 (shown in Fig. 9), which screws into the passage 7. This nut 42 has a central passage 43 forming substantially a continuation of the passage 29 in the liquid nozzlemember. A cross slot 44 in the outer end of the nut facilitates screwing the nut into position within the casing 1. The engaging beveled faces 8 and 41 serve as a centering device whereby the liquid nozzle will Aautomatically center itself within the outer nozzle housing 14 without binding or distortion of the parts. These tightly engaging surfaces 8 and 41 also serve as a liquid seal to prevent any liquid which may work its Way past the nut 42 from entering the air passage 34. A screwl plug 45 is finally inserted to close the rear end of passage 7.

Preferably an equal pressure,- which need not be over one to four pounds, is applied to A circumferential seriesA yci the air and liquid supplied through the pipes 10 and ll respectively. lt is not essential or necessary that the same pressure be used on both the air and liquid, but it is more convenient and easier to control when this is the case. rllhe liquid flows from pipe ll through passage 13 to the space 46 between the plug l5 and the rear end of nut 42. The liquid then flows through the passage h3 in the nut and the passage 29 in the nozzle member and is projected at high velocity from the restricted port 30 in the tip 31 of the nozzle as a very line stream directed through chamber 38 toward and centrally through the outer discharge port 22. The small outlet port 3G causes a pressure to be developed behind the i'ine fuel stream, which is high relative to the air pressure in chamber 33, thus 'ng great velocity to the stream. The air fiows from pipe 10 through passage l2 to the annular passage 3l, surrounding the cylindrical portion 32 of the liquid nozzle. This air then flows through grooves 39, from which it spreads into the very thin inner portion of passage S7. Since passage enlarges outwardly toward the tip 3l of the nozzle, the air will expand as it Ahows through this passage 37 into mixing chamber his rarefied air in chamber 38 otl'ers decreased resistance to the progress of the fluid stream so that its velocity is unimpeded and its substantial continuity is not broken. The air will be drawn along as an envelop about the liquid and slightly mixed there 7ith it is projected from chan'iber 38 through the discharge por;` 22.` rllhe tapering conical portion 2l of chamber 38 serves to in compress the air and fuel as the materials approach the discharge orice.

rl`he outer discharge port about twice the diameter of the inner discharge port 30, and its length should be about one and one-half times its diameter. The liquid and air will e compressed by the conical portion 21 of chambr 38 and the mixed materials will be projected from discharge port 22 at very high velocity. The relative proportions of length and diameter of the outlet nozzle, as just stated, aided by the el', .mely high velocity of the fuel stream will give a hroomy stream pread by the dischareod mixture and cause a complete atomization of the liquid. .t .ias been discovered, that by providing a sheer perpendicular front wall 23 on the nozzle, and providing sharp right angled edges to the outlet of port 22, the dribble of liquid from the outlet port, and the accumulation of liquid on the front face of the nozzle, so common in previous devices of this sort, will be entirely eliminated. Thisphenomena is bably due to the fact that the return eddy currents which set up in the outer air by devices of other forms', and which carrv the oil-laden vapor bach against the face of the Aing portions which are of iron or steel.

22 should have outlet nozzle, are avoided by this improved construction.

The inner nozzle members 25 and 26, and thefnut 42 and plug 45 are made of brass or bronze, in contradistinction to the outer cas- Since all of the parts of the atomizer will expand when heated, it is essential that these inner members have a. higher ratio of expansion to` keep the joints tight at all temperatures, especially the joint between the cylindrical portion of the inner nozzle and the walls of passage 20. lVith the metals selected as stated above, the relative ratios of expansion are such that the joints will be maintained tight at all times regardless of the temperature. Cbviously, other metals having similar relative ratios of expansion might be used. However, the temperature of this atomizer is over very high. The atomizer is positioned outside of the furnace proper, and furthermore the vaporization of the liquid at the tip will have a substantial cooling effect on this portion of the atomizer. The structure is also cooled by the streams of air and liquid flowing through the internal passages. Since the spray has a very high velocity, the flame, or tie point where combustion begins is well. beyond the tip of the nozzle 14, and hence there will be no appreciable heating effect from this source, nor any carbonization at the tip, nor inside thereof. Furthermore, if the nut l2 and plug 4&5 are made of the same metal as casing l, rust or corrosion will tahe rplacer between these parts due to the liquids held therebetween. By making these parts of dissimilar metals Lthis corrosion is avoided.

lWhile the atomizer as just described was designed more particularly for burning kerosene, it will successfully atomize much heavier fuels, or mixtures ofdiderent fuels. lt will also operate as an atomizer for various other liquids, whether used as a fuel or for other purposes. The atomizer works with'a very low initial pressure, and gives an exceedingly fine spray, and will stay clean and will not choke up even when heavy liquids are used. The device will atomize any liquid whose viscosity is such that it will flow through the interior passages.

rlhe device is particularly useful for` atomizing fuel for` the furnace of a steam automobile, or under the boiler of a. househeating plant. In such cases, a small atomizer such as here disclosedwill operate successfully on asi little as three-quarters of a quart of fuel per hour, with a continuous and uninterrupted flame propagation.

In the furnace installation shown in Figs. l and 2, a plurality or battery of these atomizers is used as indicated at A, B and C, Fig. 2. Preferably an odd number of burners will be used. The center one will always be on. If more heat is desired, two more, oneA at either" side of the original burner, may be added. For further heat a second pair may bo'added landse on up to the capacity of the installation. Inthis way, each burner will alwaysbeoperated at its full and most eicapaeity. Allof the burners or atomimmay be mounted on a common support or angle bar 2, mounted at its ends on stand- 46. The burners are mounted horimentally, or at a slightldownward inclination, pfroferably no1l exceeding forty-five degrees. :this downward inclination is not too great, therezwillbe no tendenc for the flame to lick lmek` `to the nozzle. slight inclination doln'ward insures the` 'ame passing back l when interrupted or weakened. This downinclination from the horizontal will pneferably be between and 40 degrees.

` As previously stated, the atomizers are pou, sitioned outside of the furnace proper, with the discharge nozzle A14 in line with an inlet 47 leading to the combustion chamber 48,formed of suitable refractory material. AE metallic cone 49 is mounted with its larger end fitting-within port 47 of the furand its smaller inlet end surrounding incontact with the discharge nozzle Mini-,the atomizcr. Alsecond, larger cone 50 f the cone 49, with its larger end 51 une.. from the inlet port 47 as shown in The si'ruarller end 52 of this cone 50 surrmmds, but is out of contact with the miller end of cone 49 and the discharge "iiiaale14, As bestshown in Fig. 3, this outer conef() is somewhat distorted at its larger auer end 51 sothat the upper half of this inof the cone fits closely against the uriner cone 49. This outer cone 50 serves as a meansfoa' supplying pre-heated air, for combustion purposes, to the inner cone 49. The air-libws in around the inner cone 49 at the loafer end 51' of' the'outer cone, and then )A u'es up andraround the inner cone and is naiven in through theupper smaller end of thewinner cone by the stream of atomized felffprojected thereinto. The proportions of tHe-'inner cone substantially conform to the natural expansion'ofthe Huid s ray, so that thofiame will substantially fi the larger emi of the inner cone, which become quite hot, due to the proximity of this flame, and tothe heat conducted from the furnace walls.

' this portion of the cone will not beto avoid conduction of heat from the rather hot cones to the body of the atomizer. There should be suficient clearance between the inner ends of the two cones, and between the inner cone and the nozzle 14, to permit free passage of the preheated combustion air through the outer cone, and thence around and into the inner cone. The smaller end 52 of the outer cone should come as close as possible to the atomizer (without actually contacting therewith), to prevent the drawing in of cold air at this place.

It should be understood that the air forced through the atomizer, and mixed with the fuel in discharge port 22, is primarily for atomization purposes and is insufiicient to support combustion. This lean mixture is projected from nozzle 14 as a hollow cone or spray, and additional air is necessary for combustion purposes. The burner may beinstantly ignited when cold and operated successfully in the open air, the cold combustion air being drawn from the surrounding at-` mosphere, but in this case combustion will be accompanied by the unpleasant roaring noise common to burners of this general type. Vhen the combustion air is preheated, by means of the inclosing cones described above, the process of combustion takes place easily and quietly and the roaring noise is eliminated. Also the burner is much more eilicient, since .heat units otherwise dissipated from the furnace walls and the inner enclosing cone are used to preheat the air, and thus delivered back into the furnace.

While the combustion chamber 48 here shown is a substantially S-shape passage, it is to be understood that this shape will vary for different installations, and will depend somewhat on the available space, and partly on the size and angle of mounting of the burner. The furnace here shown was designed for use in the heating plant of a steam automobile, where space is necessarily limited. At 53 and 54 are shown the water-tubes of the boiler, the heated products of combustion passing from the upper part of the S-shaped combustion chamber down among the tubes 53, under partition or baiiie vplate 55, and then up between the second set of tubes 54 on the far side of the baffle plate.

The lower and back surfaces of the combustion chamber, conforms substantially to the natural contour of the flame projected from the burner, and the cross section of the passage gradually increases to take care of the normal expansion of the heated gases so that practically no internal pressure will be developed. In fact, the pressure in the combustion chamber will be lower than atmospheric pressure, and the furnace will operate with a zero draft. With the chamber designed in this man-ner, there will be no direct impingement of the flames from the burner on the furnace walls, andthe flame will move iff along the Walls Without appreciably eroding them.

Since the preheated combustion air supplied through cones i9 and 50 passes in as an envelope around the cone of fuel spray, the

initial` con'ibustion Will be in the form of a j through the combustion chamber to utilize the full efficiency of the combustible materials. For this purpose a series of substantially tangential air passages 56 conduct air into this chamber 48 to supply air at spaced points as needed. These passages are small, so that no more air than is needed at any one place is provided. rthis not only allows the air to become preheated by its passage through the heated furnace Walls, but also prevents unduly lowering the temperature of the combustion gases Within the chamber by the addition at any Vone point of an excess amount of cooling air. In general, from the time the atomized fuel is projected from nozzle 14, until combustion of all of the fuel is completed, the combustion air is only supplied in such quantities as are actually needed at that point,

and the air thus supplied is preheated, thusv minimizing heat losses, and securing the maX- imum efficiency from the burner. Due to the curvature of the lower portion of the S- shaped combustion chamber, combustion air cannot be supplied as effectively to the inner portion of the curve as to the outer portion. It Will be noted that there is only one row of air passages 56 along this inner curved Wall. However, the radiant heat projected from the inner Walls 57 of the outer curve and concentrated upon the gases along the inner Wall 58 Where combustion is less complete, will maintain these gases at a high temperature and prevent undue cooling and carbonization at this point. p

Vhile in the installation here shown, as single combustion chamber 48 is provided for the entire battery of burners, it is to be understood that divisions may be provided if desired. to continue the individual passage of cone i9 for each burner throughout the combu stion portion of the furnace. j

Obviously, variations in the position and inclination of the atomizen and in the contour of the combustion chamber may be necessary for different types of furnaces, for eX- ample in house-heating plants, but the general principles of the construction described above may be adhered to.

A furnace of this type will be longlived,

economical of heat and fuel, and since the atomizer needs practically no adjustment, the entire combination is foolproof and reliable under variable Working conditions. Since a most desirable fuels are notavailable.

Wide range of fuels may be used, thefurnace mayfbe successfully operated evenwhen the The burners are readily started when cold by the heat of a match, hot Wire, or equivalent delvice, and no primer ork auxiliary heater of any sort is required.

` I claim:

l. rlChe method of atomizing liquid fuels, consisting in projecting a small stream of the liquid under relatively highy pressure through an expansion chamber, 'delivering tothis chamber at relatively lovv pressure an envelope offair which surrounds the fuel stream, compressing the air and liquid, and 'then projecting them lfrom the chamber as a small short stream in line with the first liquid stream. A'

Y2. The method-.of atomizing liquid fuels, consisting inA projecting a small stream of the liquid under relatively high pressure through an expansion chamber, delivering to this chamber at relatively low pressure an envelope of air Which surrounds the fuel stream, the stream and air envelope being projected from the chamber as a confined stream in line with the original liquid stream.

Y 3. The method of atomizing liquid fuels, consisting in projecting a small stream of the liquid under relatively high pressure through a low-pressure air chamber, compressing an envelope of air about the stream and atomizing the stream and envelope as they are discharged from the chamber.

4. A liquid atomizer comprising a casing having inlet passages for separately delivering air and the liquid to the interior of the casing, an inner nozzle connected With the liquid inlet and having a relatively small unobstructed discharge port projecting into an expansion chamber formed Within the casing, there being circumferential series of air passages surrounding the rear portion of the inner nozzle and communicating with an annular air passage of continually increasing cross-sectional area, Which opens into the expansion chamber around the liquid discharge port, and an outer nozzle having a discharge port in line with the inner liquid discharge port, and communicating with the expansion chamber, the liquid stream from the inner nozzle being projected through the expansion chamber and the discharge port, the chamber decreasing in size as it approaches the discharge port to compress the air around the liquid stream, the envelope of air being projected With the stream through the discharge port.

5. A liquid atomizer comprising a casing having inlet passages for separately delivering liquid and air to the interior of the casing, the casing being formed with a chamber having a cylindrical portion and a conical portion Which tapers from the front end of the cylindrical portion to a restricted dis- *6 um; 17s

eadingh'omthe casing, an in- "ner connected with the 1i uid inlet `engi -Mving a relatively-mall uno tructed port tioned axially within the anythelar r end of the comcal chamber and adapte to prjent n liquid stream the conical chamber and the disi `:charge porthe inner nozzle being exterior- 1u-1y' with its largewend positioned with- Q "111m, cylindcal ch'ambxmh Qrmmmnhr ail-passage about @am df n crossstonql arenv continutoward the hquid discharge .Y lending frm the nir inlet wmsmaller end of the annular air pgs-

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