US2574358A - Vaporizing pot type burner and pilot burner therefor - Google Patents

Description

Nov. 6, 1951 911 JOHN 2,574,358

VAPORIZING POT TYPE BURNER AND PILOT BURNER THEREFOR Filed Dec. 11, 1946 2 SHEETS-SHEET 1 9- H l /5 4 r! I 6600600000ooooooooooooooooob 1 F a a 7 f I 52 #9 I d 3 3. \+7 a; 3. l2 3 0 J o o i i i C ll 7/ /7 l 59;) l

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Znventor Roscoe N. 51* John B 91W (Ittornegs Patented Nov. 6, 1 951 UNITED STAT-ES PATENT OFFICE VAPQRI ZIN G POT 'rYPE BURNER AND PILOT BURNER THEREFOR Roscoe N. St. John, Wichita, Kans assignor to The Coleman'Company, Inc.,"Wichita, Kans., a

corporation of'Kansas Application December 11, 1946, Serial No. 715,392

ll'Claims. (Cl. 158-91) I This invention relates to vaporizing pot *type f bu'rners andparticularly to a pilOtburherth'erefor.

, -*'Inconventional vaporizing pot- 'type bu rner "installations such as in water heaters, space heaters, floor and basement furnaces or thelike,

it is highly desirable that theheat output be reduced to-an absolute-minimum during certain periods of'operation. It is well known 'that'such burners'have certain limitations in regard to the extent to which the oil rate may be reduced and {maintain clean fire operation.

X For example, a burner mightproducefiO'DOD B. t. uf 'per'h our at high fire and 8,000 to 10,000 E. t. u. per hour at low fire which is in excess of the heat required under-mild weather conditions and particularly in the middle of the'daywhen noheat' at all may be required.

It is, therefore, the purpose of the present invention to provide such burners with a pilot whereby the main burner may be relighted when -desii'ed or may be adapted to intermittent operation for supplying heat necessary to maintain a given temperature.

In accomplishing this purpose, the invention *pertains' to a pilot structure capable of contin- "nous-operation with a small clean pilotfiame disposed so as to assure prompt and positive i'gni- =-tion of the fuel immediately upon admission thereof to the burner pot.

-"Other objects of the invention are to provide a pilot that is readily adpated to a conventional pot type burner and which may be located' beneath' the low' fire ring thereof with a minimum burner pot for assisting the main burnerduring periods of transition from pilot'fire to low or high fire and during return from high or low fire to pilot fire.

3 Further objects of the invention are to provide a pilot burner which permits a greater turndown ra'tiobetween the high burning rate and the pilot burning rate without smoking of the'fire; top'rovide a pilot burner using'the same oil inlet that supplies the burner "pot for high and low fires; to provide a pilot-burner structurewhich assures substantial freedornfrom clogging of the oil inlet opening with carbon; to provide a pilot burner structure which results in a double rotary pattern of flame travel; to provide a pilot burner which promotes rapid filling of the space below the low fire ring, if such ring is used, with combustible gases and flame; and to provide a/pilot burner constructed so as to effect rapid drying up of the oil pool in the bottom of the burn r Dot after a demand for heat has been satisfied and [the oil supply is reduced.

' Inaccomplishing'theseand other objects of the invention, I have provided improved structure, a

preferred form of which is illustrated in the accompanying drawings wherein: I

Fig. 1 is a' vertical'section'through'thelower portion of a heating deviceihaving a pot-type burner equipped with a'pilot' burne'r embodying the features of the present invention.

Fig. 2 shows a portion of 'theinside of the burnenpot and illustrates'the pilot burner in perspective. I c i Fig; 3 is a fragmentary horizontahsec'tion through the burner pot'and upper-portion of the pilot burner on the line 3-3 of Fig. 1.

Fig} is a fragmentary section at a lowerelevation and taken through the pilot burner on the line fl-A of Fig. 1. c x v M Fig. 5 is a perspective view of the inside of the burner pot and'showing the pilotburner with parts broken away to better illustrate the air inlets for supporting combustion of the pilot fuel.

Fig. 6 is a perspective viewof the inside of the -lijurner pilot prior to mounting thereof in the bu p t- V Fig. '7 is an enlarged section through a portion of the pilot burner and burner pot on the line 1-1 of Fig. 4. I t i 7 Referring more in detail to the drawings;

I designates a jacket of a heating stove or the like enclosing a heating unit 2 and having air inlets3 supplying combustion supporting air to the heating unit through an opening 4 in the bottom 5 thereof. The heating unit includes a conventional pot-type burner 6 comprising a cylindrical wall 7 carrying a concave bottom 8 adapted to collect a shallow pool of fuel oil, The

oil is admitted through an inlet opening 9 in the side of the pot, the fuel oil being supplied through a connection it having a primary air supply tube I l, the inlet E2 of which is located above the level of the fuel carried in thepot.

The oil isa'dmitted at proper rate'of flowiunder control of a metering device (not shown) and on'entering the pot spreads out over a compara-- tively broad area of the bottom to maintain a shallow pool having its surface exposed to radiant heat from the fire higher up in the pot when the burner is in operation. The pool of oil is also heated by heat conducted through the wall and bottom of the pot so that the fuel vaporizes and the vapors rise within the pot to the point of combustion.

The upper surface of the oil is also exposed to a plurality of relatively small jets admitted through downwardly directed orifices I3 arranged in circular series about the wall of the pot responsive to natural draft of the flue or chimney (not shown) to which the heater is to be connected or to the forced draft of a blower. The jets are so located and directed as to create a turbulent condition in the oil vapors immediately above the heated oil surface, thus tending to carry these vapors rapidly away from the heated oil and to thoroughly mix them with a limited supply of air insufficient for ignition or complete combustion of the fuel vapors at high fire but ample for preliminary oxidation of the oil vapors so that they are prepared for combustion higher up in the burner pot where more air is admitted through a plurality of apertures M and a circular series of jets [5 at the upper portion of the pot.

When the burner is in operation, the jets of air are preheated by passage through the hot zone surrounding the burner pot with a result that the burner operates satisfactorily and results in smokeless combustion of the fuel. When a reduced heat output is'required, the rate of flow of the oil into the burner pot may be reduced so as to limit the oil area under exposure to the vaporizing effect of the heat of the fire. The heat and intensity of the burner flame is, therefore, correspondingly reduced and the flame front drops lower in the pot until the flame may consist of a plurality of jets of air burning in an atmosphere of oil-vapor-air mixture in the proximity of the air inlets in the side wall of the burner. As long as the flame front remains continuous or the oil vapor is present in proper quantity with respect to the air admitted, blue flame combustion is maintained with reduction in the oil feeding rate. However, if the oil rate is reduced too far, the tendency is for the upper flame front to become discontinuous and for the burner to draw in such an excess of air as to unbalance and chill the burning mixture and cause a smoky burner flame which may drop to the bottom of the burner pot and burn at the surface of the oil with objectionable smoke. To overcome this difficulty, the burners are provided with a low flame ring l6 located substantially midway of the height of the pot and having an inner diameter approximately half the diameter of the pot, the ring being supported on pins l1 extending inwardly from the wall of the pot at suitable points therearound as best shown in Fig. 1. The low flame ring thus serves to divide the pot into upper and lower sections, with the upper section operating for high fire and the lower when the fuel rate is considerably reduced.

The structure thus far described is conventional in pot type burners; however, as above pointed out, such burners are not adapted for most satisfactory operation under control of a thermostat because the lowest fire is too hot to serve as a pilot especially during the middle of warm days when the weather is moderating. I have, therefore, provided the burner pot with a pilot generally indicated at I8 and which is adapted to be located in the burner pot and be supplied with 4 oil through the oil inlet opening 9 to the pilot burner now to be described.

The pilot burner illustrated in the drawings may be formed of any suitable heat resistant material and includes a front wall portion I9 having the side edges 2E] and 2| provided with wing portions 22 and 23 diverging outwardly toward the wall of the pot and which are connected with the Wall of the pot in substantially parallel side wall portions 24 and 25. The lower edges 26 of the wall portions just described are shaped to conform closely with the concave bottom of the pot as best shown in Fig. 2. The front wall portion and side Wings 22 and 23 may slope upwardly from the bottom of the pot towards the side wall thereof as best shown in Figs. 2 and 5 while the side wall portions may be substantially vertical and may be anchored to the side wall of the pot as by out-turned flanges 2'! and 28 which may be secured by welding or suitable fastening devices such as bolts 29. The top of the diverging wing portions 22 and 23 have diverging outlets 30 and 3| from the interior of the pilot for a purpose later described. The top of the pilot is closed by a cap 32 having depending flanges 33, 34 and 35 that respectively overlap the side and front portions of the pilot wall. The rear edge of the cap is curved to correspond with and fit closely against the wall of the pot while the corners above the wings 22 and 23 thereof are cut away on arcs as indicated at 36 and 31 in forming the outlet openings. The lower edge of the front wall portion of the pilot also has a substantially wide but shallow notch 38 for passing fuel onto the bottom of the pot and to admit a stream of air and to provide outlet for flames adapted to play upon the bottom of the pot to maintain an elevated temperature thereof between inactive periods of the burner pot as when the main supply of fuel is shut off under action of a thermostat (not shown).

The supplementary air for aiding combustion of the oil on the pot bottom during transition from pilot to high fire is supplied through a tube or duct 39 that extends across the cap 32 and downwardly along the inner face of the front Wall portion l9 to terminate at the notch-like outlet 38. The duct also forms a divider for directing the vapors and flame in the form of a double vortex as later described. In the pilot burner illustrated, the duct 39 may be formed of a strip of metal having the central portion bent to provide a trough-like body 40 having outwardly diverging flanges 4| and 42 at the sides thereof for attachment by spot welding or the like to the underside of the cap and inner face of the front wall I9 as best shown in Fig. 6. The inlet end of the duct abuts against the wall of the pot and connects with an opening 44 through which air is admitted from the exterior of the pot for flow through the duct for discharge through the notch-like opening 38.

During operation of the main burner, the inlet 44 may be automatically closed by a heat responsive damper 44', which opens automatically when the burner returns to pilot fire.

In order to direct the discharge of air, the lower end of the duct is curved as at 45 in the direction of the center of the pot and the terminal edge thereof is rounded as at 46 to provide small outlets 41 and 48 at sides thereof for the above mentioned jets of flame.

Air is supplied to the interior of the pilot for sweeping flow across the oil which spreads across the portion of the pot bottom covered by the pilot cease- 358 through a lower series of air iinlets 49' that are covered on the insidesurface ofthepot wall by a shield 50 which extends downwardly over. the

direct and spread the air downwardly across the width of the pilot chamber.

Combustion isaided in the upper part of the pilot chamber by air admitted through a plurality of apertures 52 in the wall of the pot and located above the shield 59. A shallow depression 53 is provided in the burner pot bottom directly in front of oil inlet 9 to aid in distributing the oil over a wider area.

Assuming that the pilot is assembled and installed within burner pot as above described, that the oil inlet fitting is-connected with a source of fuel supply,and that the flow of oil from the supply to the inlet opening is under control of a flow regulating'valv'e (not shown) which may be manually or thermostaticallyoperated responsive to room temperature; the oil flow is such that when the room temperature is up to the set temperature only sufficient oil is admitted to the pot for supplying the pilot. Upon admission of the oil through the inlet opening 9, the oil spreads over the area of the potbottom 8 that is covered by the pilot chamber.. Assuming that the pilot is lighted, air is drawn, for example, by natural flue draft through the openings I2, d4, 49 and 52. The air admitted through the openings at is directed by the shield 59 downwardly toward the pot bottom 3 across the width of the pilot chamber to sweep across the oilfilm and pick up the vapors that are being generated by radiant heat of the pilot flame and by the heat conducted through the portions of the pot and pilot chamber that are heated by the pilot flame. The air is admitted in suificient quantity for partial oxidation of the oil vapors prior to ignition. As the air and vapor mixture is swept toward the front wall portion I9 of the pilot chamber it is diverted upwardly thereby toward the upper portion of the pilot chamber where it meets the secondary air necessary for supporting combustion that is being admitted under draft and which sweeps from the apertures 52 across the path of the partially oxidized vapors.

Upon contact of the vapors with the secondary air combustion is completed and flames are discharged through the openings 30 and 3! into the burner pot and below the lowflame ring l6 (if used).

Simultaneously a portion of the vapors is drawn out the outlets 41 and 48 at the sides of the notch 38 in the form of two small jets of flame that play upon the bottom 8 of the burner pot for maintaining the bottom temperature necessary to promote vaporization of the fuel in the pilot and to start vaporization of the main body of oil when it is admitted onto the main pot bottom when the thermostat calls for more heat.

Placement and maintenance of themain pilot flames inside the upper portion of the pilot chamthe apertures 52 at the upper portion of the pilot chamber not only result in ignition of the rising vapors but assurec'ompleta combustion before such vapors can escape through the: top outlet openings Wan-d 34 into the pot.

It is Well known that heatingappliances connected with chimneys or other natural draft creating means are subject to backdrafts and variable pressuredifferentials so that small pilot flames are ordinarily very unsteady and are. apt to become extinguished.

I With the present pilot burner construction, I have overcome this difiiculty by shapingthe air duct 39 to effect division -of the vapors into two separate streams as they strike the front of. the

pilot chamber. The two streams aretheri directed towards the respective side walls of the pilot chamber and. are guided by. thawings 22 reflects in rotation of the flames that are produced in the upper portion of the pilot chamber before discharge through the openings and 3L Consequently, should unsteady flue drafts cause one of the flame jets to become extinguished, the rotary action of the other flame and cross mixing between the two sides of the pilot chamber will effect immediate reignition of.the

. extinguished jet.

It is obvious that the opposed rotary action of the vapors Will stabilize the flame by pro- .viding repeated opportunities for ignition of all the fuel vapors as .they make contact with vapors which are burning within or at the outlet openings 3i] and 3! of the pilot.

. With the pilot in operation, the burner pot is kept in heated condition and prepared for the main flow of fuel whenever it is admitted tothe pot either by hand control or by actuation of a thermostat.

Upon increase in the rate of oil flow, the pilot flames automatically increase in size while surplus oil overflows onto the center of the bottom of the pot. The oil in the center of the pot then begins to vaporize and ignition is effected by the small jets of flame disposed at the respective sides of the air outlet 38. Rapid vaporization and ignition of the oil is assured due to the air stream discharged into the burner pot from the outlet 38 of the air duct 39. The air from the duct 39 spreads out over the surface of the collecting pool of oil and supplementedbythe air jets in the pot walls distributes the oil vapors as fast as they are formed in such-manner to evenly flllthe lower portion of the main burner with flame and combustible vapors. Rapidfllling of this space with combustible vapors is further facilitated through the pilot top outlet openings 36 and 3!. These top outlet openings are of a size and location to assure proper outlet velocity of combustion products and flame, and uniform distribution of excess gases and com bustion products, a practically clean smokeless fire is assured during transition from'pilot-flame through low to high fire stage.

When the thermostat is satisfied, flow through the inlet 9 is reduced to that required for maintaining the pilot fire, the oil pool on the pot bottom 8 is dried up very rapidly due tdthe jets of flames issuing from the pilot on opposite sides of the airduct 39.

From the foregoing it is obvious that I have provided a pilot for pot type burners that provides continuous, clean flames disposed to assure prompt and positive ignition of the oil when the fuel is admitted to the main burner. It is also obvious that the pilot is capable of maintaining ignition under variable chimney drafts caused by wind conditions and under downdrafts which ordinarily interfere with pilot operation.

It is also obvious that the pilot is operated with a very low oil rateduring the intervals between main burner operating periods and, therefore, does not produce objectionable heat. It is also obvious that when the fuel rate is increased the pilot flames automatically become more intense and assist the main burner during periods of transition from low to high fire and during return to pilot fire.

What I claim and desire to secure by Letters Patent is:

1. In a pot type burner having an inlet for a liquid fuel, a pilot including means within said pot forming a chamber over the inlet and having laterally spaced flame outlets at the top portion and an outlet at the bottom portion of said chamber, said burner pot having means for admitting air into the chamber, .means in said chamber fordirecting said air into the chamber for contact with vapors evolved within said chamber when the pilot is in operation, and 1 a duct having an air inlet through a side of said pot and having an outlet opening into the pot near the bottom flame outlet for discharging air near the bottom flame outlet, said duct having walls for dividing and laterally diverting said vapors and air for movement to the respective flame outlets at the upper portion of the chamher.

2. In a pot type burner having an inlet for a liquid fuel, a pilot including means within said pot for forming a chamber over the inlet and having laterally spaced flame outlets at the top and bottom portions of said chamber, means in said chamber for admitting and directing initial oxidizing air into the chamber for contact with vapors evolved within said chamber when the pilot is in operation, and a duct having an air inlet through a side of said pot and having outlet into the pot intermediate the bottom flame openings, said duct having walls diverging toward sides of the chamber for dividing said oxidized vapors into separate flows and for start ing rotational flow of said flows when moving toward said outlets at the upper portion of said chamber.

3. In a pot type burner having an annular wall and a concave bottom, a fuel inlet connection in the wall of said pot for delivering a liquid fuel for collection in pool form on said bottom of the pot, a pilot having a front portion and side wall portions cooperating with the front portion and with the wall of said pot to provide a pilot chamber into which said fuel is adapted to discharge, said wall of the pot having air inlet openings into said chamber for admitting air in contact with vapors arising from fuel admitted into said chamber, and a top for closing the top of said chamber, the front portion of said chamber having laterally spaced flame outlets under said top, a deflector carried by the wall of the pot and extending across selected air inlets for directing air downwardly in said chamber for sweeping movement across the bottom of the pot toward said front wall portion, said front wall portion having a.

lower edge resting on said pot and provided with a notch-like opening, and an air duct extending from an opening in the wall of the pot across said chamber and having a downwardly extending portion terminating in front of said notch-like opening for discharging secondary air into the pot intermediate flame jets discharged at the respective ends of said notch-like opening, said air duct being shaped to divide and deflect the air and vapors toward said first mentioned flame outlets and for causing turbulence in said flows to contact unburned vapors with burning vapors 4. A pilot for pot type burners including front and side Wall portions adapted to engage the bottom and side wall of a burner pot, a cap carried by said wall portions, said front wall portion having spaced flame outlets under said cap and a notch-like opening in its lower edge, and a duct extending across the cap and downwardly of the front wall portion for delivering air through the notch-like opening and for providing air and vapor deflecting and directing means to cause turbulent mixing of air and vapor in said chamber before discharge at said flame outlets.

5. A pilot for pot type burners including an inclined front Wall, wing portions diverging outwardly from sides of the front wall, side wall portions joining with said wings and adapted to engage a side wall of the pot, said wing portions having openings near the upper ends, a cap carried by said wall portions and having portions registering with the openings in said wing portions to form flame outlets, said front wall having a lower edge provided with a notch-like opening intermediate said wing portions, and a duct extending across the cap and downwardly of the front wall portion for delivering air through the notch in the lower edge of said front wall portion.

6. In a pot type burner having a bottom for collecting a pool of oil when the burner is in operation and having an inlet for a liquid fuel, a pilot including means within said pot for forming a chamber over the inlet and having flame outlets at the top and bottom portions of said chamber respectively, means in said chamber for directing initial oxidizing air into the chamber for contact with vapors evolved within said chamber when the pilot is in operation, a duct having an air inlet through a side of said pot and having an outlet at said bottom flame outlet for discharging secondary air into and across the bottom of the pot, and a thermostatic damper for controlling air flow through said duct, said damper being normally open when the pilot only is in operation and adapted to close when the burner is in operation to prevent admission of excess air above the oil pool on said bottom.

'7. In a pot type burner having an inlet for a liquid fuel, a pilot including means within said pot for forming a chamber over the inlet and having laterally spaced flame outlets at the top and bottom portions of said chamber, means in said chamber for directing inlet of air into the chamber for contact with vapors evolved within said chamber when the pilot is in operation, a duct having an air inlet through a side of said pot and having an outlet opening into the pot near the bottom flame outlets for discharging air near the flame outlets, said duct having walls for dividing and laterally diverting said vapors and air for movement to the respective flame outlets at the upper portion of the chamber, and a temperature responsive damper for controlling entrance of air through said air inlet of the duct.

8. In a burner pot having an inlet for a liquid fuel, a pilot including means within the burner pot forming a chamber covering the inlet and having a forward wall portion provided with symmetrically disposed flame outlets at upper and lower portions of said chamber, means for admitting air into the chamber, means in said chamber for directing said air into contact with fuel vapors evolving within said chamber when the pilot is in operation, and means extending vertically of said forward wall portion and medially within said chamber for dividing the fuel vapors and air for movement to the respective symmetrically disposed flame outlets, said dividing means having diverging sides directed toward the flame outlets and cooperating with the front wall por-- tion to direct said divisional flow and for effecing flow to the upper of the flame outlets in two upwardly rising rotary portions to mix and contact unburned vapors with burning vapors in said chamber.

9. In combination with a pot type burner, a pilot including means within the pot type burner forming a chamber having a forward wall portion provided with a flame outlet opening into the pot at the upper portion of said chamber, means for admitting a liquid fuel into said chamber, means for admitting air into the chamber for mixture of air and vapors evolved from said fuel when said burner is connected with a draft effecting means and the pilot is in operation, and deflecting means extending vertically on the forward wall portion and projecting into said chamber at one side of the flame outlet and in the path of the air and having a vertical portion joining with the wall portion for diverting said air and vapors for movement to the flame outlet in upwardly rising rotary flow in the direction of said flame outlets to mix and contact unburned vapors with burning vapors in said chamber.

10. In a burner pot having an annular walli and an inlet therein for a liquid fuel, a pilot including means within the burner pot forming a chamber covering the inlet and having a forward wall portion provided with symmetrically disposed fiame outlets at the upper portion of said chamber, means for admitting air into the chamber, means in said chamber for directing said air into contact with vapors evolved within said chambers when the pilot is in operation to effect initial oxidation of said vapors, and means extending vertically of said forward wall portion and medially within said chamber for dividing the fuel vapors and air for movement to the respective symmetrically disposed flame outlets, said dividing means having diverging sides cooperating with the front wall portion to efiect said divisional flow of said vapors and air at the respective sides of the dividing means in two upwardly rising oppositely rotating flow portions in the direction of the flame outlets to mix and contact unburned vapors with burning vapors in said chamber.

11. In a burner pot having an annular wall and an inlet therein for a liquid fuel, a pilot including means within the burner pot forming a chamber covering the inlet and having a forward wall portion provided with symmetrically disposed flame outlets at the upper portion of said chamber, means for admitting air into the chamber, and means extending verticallw of said forward wall portion and medially within said chamber for dividing the fuel vapors and air for movement to the respective symmetrically disposedflame outlets, said dividing means having diverging sides cooperating with the front wall portion to effect said divisional flow of said vapors and air at the respective sides of the dividing means in two upwardly rising oppositely rotating flow portions in the direction of the flame outlets to mix and contact unburned vapors with burning vapors in said chamber, said burner pot having air inlet openings in the upper portion of said chamber for admitting air to support combustion of the vapors in said upwardly rising rotary flow.

ROSCOE N. ST. JOHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,849,125 Valjean Mar. 15, 1932 2,162,844 Jenson June 20, 1939 2,187,261 Breese Jan. 16, 1940 2,259,845 Valjean Oct. 21, 1941 2,287,346 Fishel June 23, 1942 2,309,319 Johnston Jan. 26, 1943 2,339,614 Breese Jan. 18, 1944 2,346,816 Breese Apr. 18, 1944 2,355,416 Breese Aug. 8, 1944 2,396,675 Breese Mar. 19, 1946 2,460,013 Huston Jan. 25, 1949 2,460,014 Huston et al Jan. 25, 1949 2,490,267 Hayter et a1 Dec. 6, 1949

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