US2510482A - Pilot burner using gaseous fuel and air under pressure - Google Patents

Description

June 6, 1950 r I K. 'A. SCHARBAU ETAL 2,510,482 PILOT BI JRNER USING GASEOUS FUEL AND AIR PRESSURE Filed May 30, 1945 Patented June 6, 1950 Y PILOT BURNER USING GASEOUS FUEL AND AIR UNDER PRESSURE I Kurt A. Scharbau and Albert Stadler, Rockford, Ill., assignors to Eclipse Fuel Engineering 00.,

Rockford, 111., a corporation of Illinois Application May 30, 1945, Serial No. 596,632

The present invention relates generally to pilot burners. More particularly the invention relates to that type ofipilot burnerwhich is adapted to ignite and maintain in operation a gas burner,

such, for example, as a tube variety burner for 'pressure in stream form longitudinally through the bod y interior and has transverse inlet ports inits eentralportion for admitting air under atmospheric pressure into, and for admixture ,with, the stream of raw gas emanating from the nozzle. In practice it has been found that a pilot burner of the entrainment type is not reliable when it is supplied with butane, propane, natural gas, or any other gas having a high calorific value because of the tendency of the flameto become extinguished when the air ports in. thebody are subjected to any appreciable draft. a I

One object of the invention is to provide a pilot burner of the type under consideration which is an improvement upon, and eliminates the objections to, pilot burners of the entrainment type andis characterized by the fact that it is capable of burning any gas of high calorific value without likelihood of extinguishment of the flame as the resultof the body being subjected to a draft or unusual exterior air currents.

Another obiect'of the invention 'is to provide a pilot burner of the type and character under consideration in which the tubular body is provided at its inlet enolfwith a mixing chamber, a nozzle'for jetting air under superatmospheric pressure across the chamber and thence through the body, and'meansindependent of the nozzle for supplying raw gasto the chamber, and embodies within its discharge'end a baflle unit for reducing the velocity of the mixture of gas and air under pressure.

A further object of the invention is to provide a pilot burner'of the type under consideration whichfis generally of new and improved construction, maybe 'manufactured at a low and reasonable cost and is so designed that it possesses extremely long life.

Other objects of the invention and the Various 1 Claim. (Cl. 158-115) l 2 advantages and characteristics of the presen pilot burner-'will be apparent from a consideration of the following detailed description.

' The invention consists in the several novel features which are hereinafter set forth and are more particularly-defined by-the claim at the conclusion hereof. I x In the drawing which accompanies and forms apart of this specification or disclosure and in which like letters and numerals of reference denote corresponding parts throughout the several views: i

t Figure 1 isa top or plan view of a main tube variety burner having applied thereto a pilot burner embodying the invention;

' Figure 2 is an enlarged-vertical longitudinal section on the pilot'burner; c

Figure 3 is a perspective view of the baflie unit at thedischarge end of the tubular body of the pilot burner; and

Figure l'isa perspective view of the mounting bracket for supporting the pilot burner in operative position or relation with the main burner.

" The pilot burner which is shown in the drawin'g constitutes the preferred form or embodiment of the invention. It is illustrated in connection with a main tube variety gas burner B and serves, as 'he'reinafterdescribed, to ignite the burner and maintain it in operation. 'Amounting bracket 6 serves to support the .pilotburner in operative relation with the main burner B.- The latter is of conventional or standard construction and comprises an elongated horizontally extending tube 1) one end of which is supported by a metallic cooling well support S. Such support comprises an annular frusto-conical side wall s and 'a centrally apertured inner end wall s and is designedto fit in a fr'ust'o-conical hole in a wall of a furnace (not shown). The side wall s embodies at its'outer' end an integral outwardly extending flange 5:. The inner end of the burner tube b extends through the central aperture in the inner endwall s of the support and is secured to said inner end wall in'any suitable manner.

The burner tube is of materially greater length than the cooling well support with the result that It is inclined upwards and outwards with respect to the longitudinal axis of the throat b and provides means whereby the cornbustibleegas'and air mixture in transit through the throat b may be ignited from the outside ofi'the burner tiibe.

The pilot burner is positioned iibove thecentral portion of the burner tube b and 'operates, as

hereinafter described, to directa flame into the angularly disposed orifice b in order to maintain in an ignited condition the gas and air mixture flowing through the throat of the burner tube. It iscarr ied orsupported by: the mountingrbrack 'et'-- and comprises: ankeiongated tobular" body a nozzle '8; 'a tubular 'tip' H "and a-"bafileiunit H3;

'The body or thepilot ibur ner is preferably fo'rrned *of cast iron:and has at one end'rthereof an integral, longitudinally extending; acentrally disposed reduced stem II. The latter, easrbest shown 'in fiigure 4, i's" provided 'withran external or male screw-"thread interior :of the "tubular any 1 sshaped so asztovdefinehe lim -'di*ica1 1ongituiiina11yextenrling open ended mixing chamber 13 at the other end of the bodygand ja" longitudinally'extending' throat l t' which"lleads from the inner end of the chamberfl "tohand through the outer end -of" The mixing chamber n t materially'igreater diameter than the three =|d an I "fscrew thread l 5 at 'itswute end. "flares gradually 'lnthe d'irection herstem It, as shown in Figure 4. The nozzle B bfsthe zpilot barrier has an-open ended centrally Fdisposedz'oriertenaeig longitudin' therethrcughzand ected' by "a? pipe connection I tomeoeive r rider s'uperetrnoserierie' PIQSSHEIEfTOm 'EIW "source, sueh,' or

essdr' nd't shown). One-rend d's t-he oti ter' end of "the 3 i thetubular hody 1 and iijorffe'rn-ale'screw thr a'd DS -and "serves to'asecure a ter-diameter -tham fsafdone ror inner hodie's an annular slioulder l 9 which 5am" inst 'the end of thetubular'body lihav- .erniziiiig chamber-"13. 'The inner end ofwthe is of reduced diameter and is incend a'tibri vsfifh, arid 'of lr'naterial'ly less"Idiainsmall ":erifd-pf the' throat M, and

tion 1"! ind e the rs of theor ifice l fi' 'ridihas a male screw th-rea'd which inter-flts' er *ithezfemale screw' thread 20 sto'hold the cock intconnected relation Te nozzle. Wheh' the "cock 2! "isopen air ltbflBW'Sfifi jet'f'orrn across the'niixin'g: chamber aridwhrofigh"the throatrM. A gas "er high rialorifidvalue such as -"1arop'eoc1e, butane -:or matall gas, is supplied to the mixing chamber W3 er r'edirced estem' 1 l.

amplegas an arlr-sstorconnection 22 receives gas under atmospheric or superatmospheric pressure from any suitable source (not shown) and is indirectly connected to the end of the tubular body 1 having the mixing chamber l3 by way of an internally threaded nipple 24 which is formed integrally with, and extends laterallyirom, the bodydl; llhe port 23 communicates with thel-inner'endof the nipple and leads to the inner end of the mixing chamber 13, as shown in Figure 4. A shut-off cock 22 is includedin thepipe connection 22 in order that thesupplypf gasto the body I may be cut off when the pilot burner is not in use and adjusted "oreregulatediwhen' the pilot burner is in use. One end-:Ofthe bQdYoff the cock 22 screws into the internally-threaded nipple 24. When the cook 22 is open whilethe shut-off cock 2| is open gas enters the mixing chamber l3 via the port 23 and there mixes with the jet of air under pressure emanating from the nozzle 8 to form a combusti- 'ble'gaseous mixture which-flows from the. mixing chamber through theaflared throat- J4. .If .the gas is notunder superatmospheric. pressure it .is .drawnf'into themixingcha-mber J3. by aspiration. By reasomof-zthafactthat the throat. HLis flared .in thedireetionzoi. thesteml vI ..the velocityoi the combustible mixture-bf gasandair vunder .pressure progressively decreases asathemixture .flows from the mixingchamber to .and.through..the ex.- ternally threaded stem ll.

Th e -tubular tip 9-is preferahlyiormed pf steel and substantially the. same external. diameteras thecast iron body J. Qneendof the tip .&surrounds the reducedstem L l. attire-discharge emit of-the tubular body- Land embodiesanintervnarlscrew thread .25rwhich. is ininterfltting rela- :tion with the external. .or maleascrewx thread 12 'on the stem andeserveste holdthe tip. of thepilot in. connected relation. Thaportion of the inne periphery of the-tiptthatisoutwards of the screw thread Le is-cylindrical. .Itsis .of reduced diameterzand has attheinner end-thereof. an .annnlar outwardly extending shoulder .16 which .faces inthedireetion-and joins the inner .endef the screw-threadii. Whenthe pilotbn-rner is operation thecombustiblamixtnrerof gasand :air *underpressure, rafter passing .through the flared throat I4, flows into the tip 9'. Combustion ef t he mixturetakesplace withinthertip. and-the .flameresulting from combustion projects from the tipwas the result .of the velocityofthe mixture entering the tip.

-it he baffle await ill is located-in. the .central portion of 1 the tubular tip 3 .and serves .so- .to .rednce 'ithewelocityof r the combustible-mixtureentering ithetip .Ithat the mixtureburnslinzthe tip. -ltris preferably -of 1 one-piece xdesign ,or construction rand-comprises' a -pairofrlaterally.spaceddiscs 21 and-QBHandastemfZB between-the twodiscs. :The .disc 21 of the-baffle-unit-hasits marginal portion clamped between the :shoulderdfi-and the router end "of thereducedwsteml- |,,and :embodiesi-nwards of its clamped: margin ana annular seriesof. holes 3! Flhevdisc -28..is-.of-less;-diametenthamthe disc i i-and is disposed-outwards of the latter. .It isof slightly l-essadiameter-than the .adjacent portion :of wthewinner 1-peripheryof the-tubular tip .-.9 .and has an annular series of holese3l. -..Said. holes are angularl-y- OiTSeb-With respect to .theholes-BIl-in-the disc zi -inlorder thatrtheyiare notin registry with isuoh 1 holes. The :stem U2!! -is .iormed integrally with and extendsbetween.thecentral-.portionsof, she-two rdiscs al and 2.8, and servesltorholdthezlatter in rigid ofiset onelaterallyspaced-relation. ,In

"'o'f 'a' pipe' cpnnection $22 arrd'.= port 13; "Thapipe zcon-nection w-ithroperationrofrthe pilot hurner-the combustible mixture" of gas and air under pressure, after travelling or flowing throughthe flared throat l4, passes'first throughthe holes 39 in the disc 21 and their through the space between the a two discs. Afterxpassing through such space a portion of the mixture flows through the holes 3| in a the disc 28 andthe balance flows around the said area of the holesin each disc 01' the bailie unit is materially less than the area of the discharge end of the flared throat H in the tubular body 1. Because of the design and construction of the pilot burner the latteris capable of burning any gas of high calorific value without likelihood of the flame emanating irom the tip being extinguished by a draft or unusual exterior air currents.

The mounting bracket 6 is located at one side of the central portion of the tube b of the main gas burner B. ,It isI-shaped and comprises a vertically extending intermediate piece. 32, an

elongated horizontally extending upper crosspiece 33, and an elongated horizontally extending lower crosspiece 34. The upper end of the vertically extending intermediate piece 32 is provided with a cylindrical part 35 having a centrally disposed longitudinally extending bore 36. The tip 9 of the pilot burner extends through the bore 38 and is releasably secured in place by make it possible angularly or rotatively to adjust the bracket about its longitudinal center or axis. By adjusting the mounting bracket 6 laterally by way of the slots 39 and 4| and angularly or rotatively adjusting the bracket by way of the set screws 44 the bracket may be so positioned that the axis of the tubular tip 9 of the pilot burner intersects or is in alignment with the angularly disposed orifice b in the upper portion or discharge'end of the tube b of the main gas burner B. The central portion of thevertically extending intermediate piece 32 of the mounting bracket is provided with an integral laterally extending lug 45 which fits within a groove in the main burner tube b and serves to hold the ,main burner tube against rotation relatively to the bracket 6 and the cooling well support S. When it is desired to mount the pilot burner with respectto the main burner B the tip 9 is inserted through the bore 36 in t e cylindrical part-35 at the upper en of the vertically extending intermediate piece 32 of the mounting bracket means of a set screw 31 which extends through a screw threaded hole in the outer side portion of the cylindrical part 357 The pilot burner is arranged so that the tubular tip 9 thereof is disposed within the cooling well support S. The bore 36 in the cylindrical part 35 on the upper end of the intermediate piece 32 of the mounting bracket is so canted or angularly arranged that when the pilotcburner is in assembled relation with the mounting bracket the axis of the tubular tip 9 is substantially in alignment with the outer end of the angularly disposed orifice b in the upper portion of the discharge end of the tube 11 of the main burner B and hence the flame emanating from the tip of the pilot burner is directed towards the orifice. The upper crosspiece 33 of the mounting bracket 6 is positioned adjacent the upper portion of the flange s of the cooling well support S and is secured thereto by way of a bolt 38, the shank of which extends through a horizontal slot 39 in the upper crosspiece 33 and fits within a threaded hole in said upper portion'of the flange s. The lower crosspiece 34 of themounting bracket is positioned adjacent the lower portion of the flange s and is secured in place by means of a bolt, the shank of which extends through a horizontal slot 4| in the cross piece 34 and fits in a threaded hole in said lower portion of the flange s. The slots 39 and 4| permit the mounting bracket to be adjusted laterally with respect to the tube b of the main burner B and also permit the bracket to be tilted about its center in either a clockwise or counterclockwise direction. The ends of the upper crosspiece' 33 of the mounting bracket are provided with transversely extending set screws 44 and these abut against the upper portion of the flange s of the cooling well support S and lation with the aforementioned groove.

8 and issecured in place by tightening the set screw 31. Thereafter the bracket with the pilot burner connected thereto is positioned along side of the central portion of the main burner tube b and is shifted laterally in order to bring the laterally extending lug 45 into interfitting re- After so positioning the bracket the bolts are inserted through the slots 39 and 42 and are screwed part way into their respective threaded holes in the flange s of the cooling well support S. After such o eration the bracket is adjusted laterally and tilted to the proper extent and then is angularly or rotatively adjusted about its center by adjustment of the set screws 44. When the bracket is so positioned that it serves to hold the pilot burner in such position that the axis of the tubular tip 9 is in alignment or intersecting relation with the orifice b the bolts are tightened to the fullest extent.

When it is desired to operate the main gas burner B the pilot burner is lighted by first opening the shut-ofi cocks =2| and 22 and then placing a lighted match adjacent the discharge end of the tubular tip 9. As soon as the pilot burner is ignited or lighted it produces a flame which is directed into the angularly disposed orifice b in the discharge end of the main burner tube b. Upon supply of a mixture of gas and air under pressure to the main'burner tube the mixture is ignited in the flared discharge end of the throat I) of the main burner tube by the flame which enters the main burner tube via the orifice b.

The herein described pilot burner effectively and efficiently fulfills its intended purpose and as previously pointed out is characterized by the fact that it is capable of burning any gas of high calorific value without likelihood of extinguishment of its fiame as the result of the body of the pilot burner being subjected to a draft or unusual exterior air currents. It is contemplated that the pilot burner will be in operation at all times during operation of the main burner in order that it will ignite the main burner should the latter go out as the result of a back-fire.

The invention is not to be understood as restricted to the details set forth since these may be modified within the scope of the appended claim without departing from the spirit and scope of the invention.

Having thus described the invention what we 2 having. a idischargeiflriflce facing, andin cenitered relation-withgthe .small end of the throat, and :prcvided with means for supplying =it with Jlir under wi supergtmospheric ,prpssure, .meems QQllleQt Bd tap-said. one endof {one bodyionsupml in awv ga s togth mm grwentry. into, .the m. in mkfi lianaa p mwith ml meme It verselyxtnding 6156 having 'thernargihal pop x-tion thereof cramped between the shoulder and Number Date Coun try Q France .Li Mar. 30, 1936

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