US2213862A - Oil burner - Google Patents

Description

Sept. 3 1940. 2 D, J, HOWARD 2,213,862

on, BURNER Filed Nov. 18, V195s aaalldllpllfill.

Patented Sept. 3, 1940 PATENT OFFICE OIL BURNER David J Howard, Chicago, Ill., assignor to Quaker Manufacturing Company, Chicago, Ill., acorporation of Illinois Application November 18, 1938, Serial No. 241,171

9 Claims.

My invention relates to an improvement in a method of and means for controlling the air supply to pot type liquid hydrocarbon burners.

One purpose is the provision of means for ob- 5 taining a diierential I cooling effect at low or natural draft and at high draft.

.Another purpose is the provision of means for supplying air under pressure to a pot type burner 1 whereby, as the air pressure or air flow increases is prevented.

Another purpose is the provision of means for by-passing air whereby as the pressure is increased about-thepot, a substantial proportion of the additional air supplied ows to the general area of the upper air inlet or inlets without having a cooling eiect upon other parts of the pot.

Another purpose is the prevention of capacity loss and dame pulsation which would otherwise be caused by the cooling effect of an increased air supply or air pressure.

Other objects will appear from time to time in the course of the specification and claims.

I illustrate my invention more or less diagram- 25 matically in the accompanying drawing wherein:

Fig. 1 is an elevation partly in vertical section; and

Fig. 2 is a vertical section on an enlarged scale of a portion of the structure which is shown in Fig. l.

Like parts 'are indicated by like characters throughout the specification and drawing.

Referring to the drawing, I indicates a mixing and combustion pot having a bottom 2 preferably 3,-, of thin sheet metal, a plurality of air inlets 3, and anA upper row of air inlets 4. is a top baiile which may if desired partially-close the open top of the pot, the mixture and iiame being thereby restricted to the central opening 6. 1 is an additional baiile which may, if desired, be located in a lower portion of the pot at various levels. It may be selectively positioned upon any one of a plurality of sets of studs or inward projections 8, 8a and 8b, shown extending inwardly into the interior of the pot I at different levels.

II) is a closed exterior housing connected to the pot I as by the top partition I I. The details may be varied but I illustrate. the top partition II as welded to an outwardly extending flange I2 of the pot'wall member I. The member II may include a downwardly extending flange I3 which may be removably secured as by screws to the. top of the closed housing member I0. The member I0 has a closed bottom I4.

I5 indicates an air inlet duct in communicaat high lire, an excess cooling effect on the pot tion with the interior o f the housing I0. Aty its outer end, the duct I5 is in communication with the air outlet member I6 of the fan housing I'I. Any suitable fan blade structure I8 may be rotatably mounted therewithin and may be actu- 5 .ated by any suitable motor, not herein shown in detail. l

I9 is a liquid fuel supply duct terminating as at in an inlet member in communication with the bottom member 2 of the pot. 2|, 22 are any 10 suitable `supports or pedestals, the details of which do not of themselves form part of the present, invention. The duct I9 extends to any suitable source of supply of a liquid hydrocarbon and any suitable means may be employed, not l5 herein shown, for varying the ilow of the liquid hydrocarbon in order that a controlled volume ofv liquid hydrocarbon may be delivered tothe bottom member 2 of the pot. f

It will be understood that any suitable control 20 means are employed whereby the fan member I8 may be actuated or may be maintained inactive at the option of the user or upon the employment of thermostatic controls which are conventional in the art. It will be understood further that any suitable means may be employed, not herein shown in detail, for permitting a natural draft of air tol flow inwardly along the duct I 5 to the interior of the housing Ill when the fan I8 is not being actuated. It will be understood that air may be supplied to the apertures 3 or 4 either by natural draft or by the operation of the fan, whereby a substantial variation in air supply is maintained, depending upon the operators need for heat or the actuation of the thermostatic controls.

In a furnace of the present type, it has been customary to deliver air about the bottom member 2 for passage upwardly around the exterior of the pot to the air inlet apertures 3 and 4. This has the advantage of cooling the bottom of the pot and preventing overheating and burning out of the thin sheet metal parts often employed. It is disadvantageous, however, since when theair supply is increased, an increasing Volumeof air iiows across the bottom of the member 2 in order to support the higher re, this increased air flow causing an increased cooling effect on the bottom 2. This cooling effect not only tendslto del crease the capacity of the burner but causes an uneven pulsating iiame.

I therefore find it desirable to provide means, effective primarily during fan operation or at high natural draft, for by-passing a portion of the increased air supply for high flre, whereby this increase in the air supply may be obtained without a corresponding increase in the cooling eifect of the necessary increased air flow.

I iindas a practical solution of this problem the employment of an intermediate shell or housing member 30 which is herein shown as vhaving an upper flange 3| which may be Welded or otherwise secured to the bottom of the partition member II. It is shown as having a bottom 32, with a central air inlet aperture 33 which may for convenience be' alined with the central portion of the exterior of the bottom member 2. It is also provided with a plurality of air inlets 34, preferably arranged in an upper portion of the member 30. These air inlets, which of course may be widely varied in size, shape, number and location, are preferably generally alined with or located in general opposition to they upper air inlets 4 or the upper air inlet zone at the top of the pot member I.

The total cross sectional area of the apertures.

eral at low draft, theair Whichilows inwardly along the duct I5 will for the most part flow directly upwardly through the aperture,y 33 and against the bottom of the member 2, to have its appropriate cooling effect, and will ow upwardly about the pot to supply the air inlets 3 and eventually the upper air inlets 4.

It will be understood that at very low flame, or at pilot ame, the apertures below the bale 1 will provide the primary air supply, and the lapertures above the bale 1 will fall in the category of secondary apertures. At this low-burning stage, there is an insuicient air supply to cause any undesired or undesirable cooling of the bottom 2.

When the operator turns up'the fire, whether by direct manual operation or by the interposition of lany suitable thermostatic control means, the fuel supply along the duct I9 may be increased an'd air is delivered under pressure from the fan I8 along the duct I5. As soon as any substantial air pressure builds up in the space within the housing I0, air will by-pass in increasing volume through the apertures 34. The flow of air upwardly through the aperture 33 will not increase suiciently to have any unfavorable cooling eiec't on the bottom 2. An increasing proportion of the air supplywill pass through the apertures 34directly to the upper zone, Where the increased suppiy is necessary.

Itwill vbe understood that at high re the secy ondary air flows vthrough the apertures 4, the 'apertures 3 providing the primary air supply for:-=

the preliminary mixture. I `'Ihus at high re, when the secondary air supply is delivered through the top row of apertures 4, the greater portion of the additional air necessary for this secondary air supply ows upwardly between the housing I0 and the intermediate member 30, and through the apertures 34, having no cooling effect whatsoever on the bottom of the pot 2, and avoiding any tendency to reduce, by such cooling, the capacity of the burner.

There is thus a differential effect obtained in response to an increase in draft or air pressure, and much of the increased supply of air necessary for a higher fire is supplied directly to the` secondary zone through the apertures 34, there being little increase of air flow across the exterior of the bottom 2. Thus I am able to increase the air supply for high flame without any substantial increase in the cooling effect of the air.

on the bottom 2. 'Ihis increases the capacity of the burner and prevents that pulsation of name .which takes place when there is a contest between the cooling effect of the innowing air on the bottom 2- and the heating effect of the increased fire above the bottom 2.

A further function of the shield or intermediate member 30, in connection with the structure with which it is employed, is in preventing undue heating of the air supply which flows through the apertures 34. I find by experience that there is an actual increase in capacity obtained by supplying relativelyv cool air to the apertures 4, yat high ame, when the apertures 4 are serving as the source of secondary air for the high flame.

If the air is unduly heated, it expands and the effective amount of oxygen per cubic unit of the inowing heated air is correspondingly reduced. Hence, I am actually able to obtain a greater oxygen supply per cubic unit of inflowing air by keeping the air relatively cool.

The wall 30, in connection with the insulating and coolingeiect of the upward current of air vbetween the pot I and the intermediate member 30, is effective to keep the air between the members IIl and 30 at a relatively'low temperature,

'with a consequent increase in effective oxygen content per cubic unit. Y

It will be realized that whereas I have described and shown an improved structure and method, nevertheless many changes may be made in the size, shape, number and disposition of parts and in the details and steps of such method without departing from the spirit of my invention. I therefore wish my description and drawing to be taken as in a broad sense illustrative and diagrammatic, rather than as limiting me to my precise structure.

I claim:

1. In combination, in a 'pot type burner, a pot having a bottom and a circumferential side Wall,

said side wall having air inlet means in a lower portion thereof and a plurality of air apertures in an upper portion thereof, means for supplying combustion air under pressure to said burner, including means for delivering air across the exterior of the bottom of said pot for supplying air to said apertures,rsaid air being effective to cool said pot bottom, and means for by-passing part of the air from the supply along a path separated from the bottom of said pot, to theA general area of the upper air apertures, whereby an additional supply of air may be provided without a corresponding increase yin the ow of air acrossthe` sovcluding means for delivering air across the exterior of the bottom of said pot for supplyingair to said apertures, said air being electiye to cool said pot bottom, and means for by-passing part of the air from the supply along a path separated from the bottom of said pot, to the general area of the upper air apertures, whereby an additional supply of air may be provided without a correspondingincrease in the flow of air across the potbottom, said means including a shield interposed between the air supply andthe exterior of said pot, said shield being apertured in line with the bottom `of said pot and in line vwith an upper portion of said pot, the apertured area of the bottom of the shield substantially exceeding the apertured area of the top portion of the shield.

3. In a burner for liquid hydrocarbons, an inner pot member having a circumferential wall, a plurality of air apertures in the lower portion oi.' the wall, a plurality of air apertures in the upper portion of the wall, an outer housing surrounding said pot, means for supplying air to said outer housing, and shielding means intermediate said innerlpot and vouter housing, said means being apertured to direct air from said housing against the bottom of said inner pot member and having additional apertures for supplying air from the housing to 'the pot alined' with an upper portion of said inner pot.

4. In a burner for liquid hydrocarbons, an inner pot member having a circumferential wall, a plurality of air apertures in the lower portion of the wall, a plurality of air apertures in the upper portion of the wall, an outer housing surrounding said pot, means for supplying air to said outer housing, and shielding means intermediate said inner pot and outer housing, said means being apertured to direct air against the bottom of said inner pot member and having additional apertures alined with an upper portion of said inner pot, the apertured area of said upper portion of the shield being 'less than the apertured area of the lower portion of the shield.

5. In a burner for liquid hydrocarbons, an inner pot member having a multiple apertured cir-` cumferential sidewall and a closed bottom, a closed outer Ihousing surrounding the sides and bottom of said pot, means for supplying air under selected pressure to said outer housing, and an intermediate shell interposed between said inner pot andvouter housing, said intermediate shell having an opening in its bottom in line with the bottom of said pot member; and being additionally apertured in its upper side portion in line with anv upper portion oi' said 4pot member.

6. In a burner for liquid hydrocarbons, an in ner pot member having a multiple aperturedcircumierential side wall and a closed bottom, a closed outer housing surrounding tbe'sides and bottom of saidpot, means for supplying air under selected pressure to said outer housing, and an intermediate shell interposed between said inner pot and outer housing, said intermediate shell being apertured in line with the bottom oi' said pot member, and being additionally apertured in line with an upper portion of said pot member,

the bottom aperture area of said intermediate means exceeding the upper aperture area.

7. In combination, in a pot type burner, a pot having a bottom and a circumferential side wall, said side wall having a plurality oi air inlet apertures located at various levels therein, means Vior delivering air across the exterior of the bottom of said pot to the lower of said air inlet apertures, and for delivering air to the upper of said apertures at a relatively low temperature by shielding the air so delivered, whereby the heating effect thereon of the proximity of` the pot is substantially reduced, said means including an outer housing surrounding the sides and bottom or the pot, means for delivering air to said outer housing, and an intermediate shield between said outer housing and pot; said shield being aper-L1 tured in line with the bottom oi' the pot and in general alinement with the upper air inlet apertures. l

8. Inl a burner for liquid hydrocarbons, an inner pot member having a closed bottom and a substantially cylindrical side wall provided with a plurality oi' air apertures including a circumferential series adjacent the upper end oi' the pot,

, an outer housing enclosing the sides and bottom of the pot, means for delivering air under selected pressure into the housing, and means posiltioned between the housing and pot for directing a portion of this air in contact with the bottom of the pot before it passes through the apertures, and for positively shielding another portion of this air from engagement with the lower portion of the pot and by-passing this air direct to the upper series of apertures. l

9. In a burner for liquid hydrocarbons. an inner pot member having a closed bottom and a substantially cylindrical side wall provided with a plurality of air apertures including a circumferential series adjacent the upper end of the pot. an outer housing enclosing the sides and bottomoi' the pot, an intermediate shell positioned in the space between the housing and'pot and dividing this space into an outer space between the housing and shell, and an inner space between the shell and pot, means for delivering air under selected pressure into the said outer space, the shell being closed except `for an opening in its bottom and apertures adjacent its upper end through which air passes from the outer space to the inner space and thence through the apertures in the pot wall.

DAVID J. HOWARD.

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