US2084708A - Apparatus for burning liquid fuel - Google Patents

Description

June 22, 1937. R. M. SHERMAN APPARATPIS FOR BURNING LIQUID FUEL 2 Shee'ts-Sheet 1 Filed March 30. 1955 n a a my v WNW I 7. m. Z d\mw Zfi 1 MM mm 3 x. M o m..,.wo.. 0 9: m6 Q \m mm \M June 22; 1937. R. M. SHERMAN APPARATUS FOR BURNING LIQUID FUEL 2 Shee ts-Sheet 2 Filed larch 30, 1935 wuzn,

Patented June 22, 1937 UNITED STATES PATENT OFFICE APPARATUS ron BURNING mourn rum.

necticut Application March 30, 1935, Serial No. 13,901

7 Claims. (Cl. 158-78) This invention relates to apparatus for burning liquid fuel (herein referred to for descriptive Purposes as oil) and deals more particularly with burners of the so-called gun type.

In my prior application, Serial No. 717,967, filed March 29,- 1934, there are disclosed certain novel features relating to oil burners, one object of which is to so control the intermingling of the air and the oil in the combustion chamber as to increase the eifectiveness of combustion, this being there accomplished by imparting to the air such a progressive rotary movement and so controlling its discharge into the combustion chamber and its relation to the oil spray that it emerges in substantial coincidence with the latter.

This object is attained in part by imparting to the body of air traveling through the air conduit a high momentum rotary movement without substantial turbulence so that, so far as practicable, it is discharged as a helically moving air mass, this condition being established in the embodiment of the invention illustrated in the aforesaid prior application by the provision of 25 inclined or helically arranged elements, preferably in the form of vanes, ribs or the like, on the inner walls of the conduit and extending a substantially distance from or adjacent the mouth of the conduit back toward the air-enter- 30 ing end thereof.

I have found that a progressive and accelerated rotary movement of the air initiated soon after its entrance into the air conduit serves best to accomplish the result sought after and 35 provides for a minimum of disturbing turbulence in the air mass. I have further found that the helically inclined elements utilized to effect such rotary movement may be so shaped, proportioned and disposed as to secure such high 40 momentum rotary air movement with a minimum of turbulence and noise, and in a conduit of a length relatively short as compared with the volume of air dealt with, thereby providing material advantages in all cases and particularly 5 in the case of burners of large capacity.

This and other objects of the invention will be best understood by reference to the following description when taken in connection with the accompanying illustration of one specific em- 50 bodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is an elevation, partly in section, showing the general construction of an oil burner 55 embodying one form of the invention;

F18. 2 is a side elevation of the removable front end of the tubular air conduit, showing in dotted lines the disposition of one of the helical vanes;

Fig. 3 is a cross-sectional elevation of the air 5 conduit, taken on the line 33'in Fig. 2 near the air entering end of the conduit, and looking toward the discharge end thereof, the full length of the vane shown in Fig. 2 only being indicated in elevation; 10

Fig. 4 is a similar cross-sectional elevation, taken on the line 4-4 in Fig. 2;

Fig. 5 shows in sectional plan, on the line 5-5 in Fig. 3, the straight line development of one of the helical vanes; 15

Figs. 6, 7 and 8 are fragmentary cross-sections, taken on the lines 6-6, '|'I and 8-8, respectively, in Fig. 2, and showing the shape in successive positions of the blade indicated in Fig. 2; and

Figs. 9 and 10 are cross-sectional elevations showing different forms of adapting bushings for varying the contraction of the discharge end of the conduit.

Referring to the embodiment of the invention here submitted for illustrative purposes, the burner is equipped (Fig. 1) with a rotary air impeller II having a central air intake of the so-called Sirocco type. This comprises a disk l3 mounted on a driving shaft l5 and a spaced opposed annular plate ll with interconnecting multiple vanes or blades. At the prolonged end of the driving shaft is connected the oil pump l9 and at its opposite end (not shown) an electrical driving motor.

The impeller is contained within a housing 2|, the upper part of which is generally cylindricalin form, having its end wall or head facing the motor closed except for the opening through which the driving shaft extends, and the opposite side or end wall facing the pump provided with an air admission opening aligned with the opening of the annular plate ll of the impeller. The amount of air admitted through the air admission opening is controlled by a disk-shaped shutter 23 which may be adjusted to a fixed position axially of the shaft l5 after the burner has been installed and its air requirements determined.

The impeller, which rotates in the direction of the arrow in Fig. 1, is mounted in eccentric relation to the peripheral walls of the housing so that the clearance between such walls and the impeller is at a minimum at the point designated 25 in Fig. 1 (and which may be termed the point of air registry), but gradually increases from that point to the discharge portion of the housing at the bottom thereof. At the bottom or-air discharge portion of the housing, the latter merges into a prolonged straight cylindrical tubular conduit member 21 having an open mouth at its forward end and extending in a general direction at right angles to the axis of rotation of the impeller and in tangential relation to the discharge portion of the housing, so that the body of air emerges from the housing in a straight line direction from the impeller to the mouth of the conduit without other obstruction than the parts contained in the conduit hereinafter described.

Positioned axially within the conduit is an oil delivery pipe 29, terminating just short of the conduit mouth in a nozzle 3| and entering laterally into the conduit at 33, where it has external connection to the oil supply pipe 35 extending to the discharge side of the pump IS, the supply pipe 31 being connected to any suitable source of supply (not shown) such as a main storage tank. The usual accessories, such as reducing valves, strainers, etc., are omitted for the sake of simplicity. Liquid oil, without premixture with air, is supplied by the pump to the nozzle at substantially high pressure, for example, between 80 and 125 pounds and preferably within the neighborhood of pounds per square inch, so that a high pressure mechanical atomization is produced at the nozzle, the liquid oil being discharged therefrom in the form of a cone-shaped spray subtending an angle which may vary according to the type of nozzle employed but which is usually between 45 and 80 degrees.

To ignite the commingled oil and air, one or more sparking electrodes 39 (herein two in number) are employed in advance of the nozzle and connected each to a conductor M, the latter being mounted in rigid, non-conducting sleeves 43 of porcelain or other like insulating material, the conductors entering the conduit through the bottom walls thereof at the points designated 45.

On the installation of the burner, the forward end of the conduit is entered into and sealed within the walls 41 of the combustion chamber, the latter being sealed against any substantial admission of air other than that delivered through the conduit, so that substantially the entire air supply for combustion is delivered through and released from the open mouth of the conduit with the liquid oil spray delivered from the nozzle 3|.

To maintain the nozzle in central position and the electrodes in fixed relation to the nozzle, a support 49 is provided in the forward end of the conduit, such support being preferably constructed, as described in my aforesaid prior application, of thin sheet-metal presenting its edges to the air flow or otherwise so constructed as to offer a minimum of resistance to the air traveling through the conduit.

As shown in the drawings, the housing 2| and the conduit 21 are formed of three parts. One of these includes substantially the lower half 2 Id of the impeller housing and the immediately parti-cylindrical adjacent part 2111 of the tubular conduit, terminating in an unbroken forward cylindrical ring-like end 21b.

A second part comprises an interfitting an separable upper casting which is removable as a single piece and includes substantially the upper or companion half Zlb of the impeller housing carrying the point 25 of air registry and the upper half or companion parti-cylindrical portion 210 of the conduit 21. The upper separable part of the casing is provided witha flanged front wall 51, the bottom wall 53 and the back wall55 adapted to lie and fit over the opposed mating walls of the lower part, being held in'position thereon by, set screws 51, and 59, so that when applied in place, the upper portion may be fastened securely but maybe instantly removed after loosening the set screws.

The third part referred to comprises the foremost end of the tubular air conduit comprising a cylindrical barrel 6! fitting into the forward end 21b of the tubular air conduit and held therein by set screws 63. This provides a removable tubular extension of the air conduit, passing through the combustion chamber walls and having interiorly the means for imparting to the air mass the rotary movement referred to.

Referring now more particularly to the means for progressively impressing a rotary motion on a body of air forced through the conduit, such means herein comprise a series of helically disposed ribs or vanes '65 projecting inwardly from the inner walls of the tubular extension iii of the air conduit and extending. back from near the mouth of such extension to approximately the opposite or rear end thereof. The height, number, pitch and length of these vanes may be varied. As a specific numerical instance only, in the case of a tubular conduit having an inside diameter of 4% to 5 inches, I have found satisfactory an arrangement employing eight equally spaced helically disposed vanes, each having a substantially uniform height or inward projection of about of an inch, extending for a distance of 9 inches measured along the axis of the conduit, and each having a pitch which provides for one-quarter of aturn in its length.

When the air enters the vaned or rified portion 6| of the tubular conduit, it encounters the projecting helically inclined vanes and the latter initiate the rotary movement of the air body. To best carry out the object of the invention and avoid disturbing turbulences, such rotary movement should be relatively gentle at first, but progressively increase in force as the air advances, reaching a maximum at or just prior to the delivery of the air at the mouth of the conduit. This is provided for by so disposing the vanes as to intentionally provide for a certain amount of slippage of the air over the vane at the air entering end of the conduit and progressively decreasing such slippage toward the delivery end, this result being had in the illustrative embodiment of the invention by a progressive variation lengthwise in the cross-sectional shape of the vane.

Referring to Figs. 3 to 8, inclusive, such variation is illustrated in respect to the vane designated in Fig. 2 as 65a. While the air may be given either a right-handed or left-handed rotation, in the illustrated form of the invention the vanes are inclined to turn right-handed or clockwise so as to impart a clockwise or right-hand rotary movement to the body of air. Each vane, as for example vane 65a, therefore presents in opposition to the air the side designated 61 in Figs. 3 to 8 of the drawings. At the air entering end, the side 61 (as shown in Fig. 3) has a marked slope or inclination so that an element thereof defined by a cross-sectional plane through the conduit is inclined or sloped away from a similarly defined radius extending from the center of the'conduit to the vane. An element on the opposite or companion side ll of the vane, at the same point however, is parallel to or substantially coincides with such a radius.

'5 This provides for imparting to the advancing air a gentle rotary movement accompanied by a substantial amount of slippage over the inclined.

. vanced point, such as half way lengthwise the vane (represented by the cross-sectionline |--l in Fig. 2), the vane reaches such a shape that an element defined by a cr'oss-sectionahplane is parallel and in approximate coincidence with a radius extending from the center to the vane, providing thereby for a relatively greater effectiveness in impressing rotary movement on the body of air. From the half-way point to the end of the vane, the side 61 maintains its radial relation, as indicated by Fig. 8 (a cross-section on the line 8--8'in Fig. 2) and Fig. 4 (a cross-section on the line ll at or near the end of the vane).

The opposite or companion side 88 at the same time undergoes a variation in its slope or relationship which is the reverse of that of the side 61. That is to say, at the successive positions referred to lengthwise the conduit, from the air entering end to the mouth thereof, it maintains its radial relationship until the half-way position is reached (Fig. 7), after which it slopes away from the radius (Fig. 8) until the end of the blade is reached (Fig. 4) where its slope has so increased that it corresponds substantially but is in reverse relationship to the slope of the side 61 at the air entering end. This shape of the vane is shown in the straight line section development in Fig. 5. This arrangement provides in a relatively short conduit for a slow movement of rotation at the air entering end, with pro-,

gressively increasing intensity, until the air reaches the mouth of the conduit when such rotary effect is at a maximum, the result being that a high momentum rotary movement of the air is secured at the point of air emergence without the production of interfering turbulences and accompanied by little or no noise.

In order to bring the helically traveling body of air into proper relationship to the cone-shaped oil spray, as explained more fully in my aforesaid prior application, the body of air should emerge through a contracted mouth at the end of the conduit so as to discharge first as a contracting helix of progressively moving air but tending to become soon after emergence an expanding helix of advancing air. Such contraction should be effected without turbulence and without substantial movement of the rotary air, and the degree of contraction will depend in different cases on the position and size of the oil nozzle, the oil pressure employed, the angle subtended by the oil spray, and on the velocity and volume of the air.

These are conditions which in the case of the same burner may require variations or adjustment to adapt it to different installations, dependent on local conditions encountered, as, for example, the type of heater, conditions of draft and on the combustion chamber. This in turn may require different degrees of contraction at the mouth of the conduit. To provide for this, the mouth of the conduit is herein contracted by means of a removable member, in the form of a bushing, adapter or insert Ii (Fig. 1), held in position by a set screw II. This presents a lining for the tip of the conduit having smooth, inner, converging walls terminating in a contracted mouth of lesser diameter than the inside diameter of the conduit. If a lesser contraction at the mouth of the conduit is required, there may be substituted for the insert II a bushing having a, larger mouth, such as the member I3 (Fig. 9), or if a greater contraction is required,

then a bushing having a smaller mouth may be used, such as the member 15 '(Fig. 10).

While I have herein disclosed for purpose: of illustration specific details and measurements of one embodiment of the invention, it is to be understood that these are suggestive only and may be varied widely, all without departing from the spirit of the invention.

v I claim:

1. A liquid fuel burner for supplying a mixture of liquid fuel and air to be burned in a combustion chamber, said burner comprising a cylindrical air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, successive cross-sectional planes taken through said vanes near their air receiving ends each defining elements on the air opposing face of each vane having a sloping relation to a radius of the air conduit in the respective crosssectional plane and extending to the particular vane, to allow for an initial-air slippage, said sloping relation and air slippage decreasing toward the mid-portion of said vane, said elements as thereby defined, thence to the forward end of the vane, substantially coinciding with said radius, and the said planes further defining elements on the opposite face of said vane having substantial coincidence with said radius up to the mid-portion of the vane and thence to the forward end thereof having an increasing sloping relation to said radius.

2. A liquid fuel burner for supplying a mixtu e of liquid fueland air to be burned in a combustion chamber, said burner comprising a cylindrical air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, successive cross-sectional planes taken through said vanes near their air receiving ends each defining elements on the air opposing face of each vane having a sloping relation to a radius air conduit terminating in an open mouth, means for forcing air through said conduit, a. spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, a cross-sectional plane taken through the mid-portion of the vane defining elements on opposite sides of the vane substantially parallel to a radius of the air conduit in said cross-sectional plane and extending to the said vane, the said elements on the air opposing side of the vane having a progressively increasing sloping relation to said radius in a direction toward the air receiving end of the vane, and the said elements on the opposite side: of the vane having a progressively increasing sloping relation to said radius toward the opposite end of the vane.

4. A liquid fuel burner for supplying a mixture of liquid fuel and air to be burned in a combustion chamber, said burner comprising a cylindrical air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, a cross-sectional plane taken through the mid-portion of the vane defining elements on opposite sides of the vane substantially parallel to a radius of the air conduit in said cross-sectional plane and extending to the said vane, the said elements on the air opposing side of the vane having a progressively increasing sloping relation to said radius in a direction toward the air receiving end of the vane.

5. A liquid fuel burner for supplying a mixture of liquid fuel and air to be burned in a com bustion chamber, said burner comprising a cylindrical air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, successive cross-sectional planes taken through said vanes near their air entrance ends defining elements on the air opposing face of each vane having a sloping relation to a radius of the air conduit in said crosssectional plane and extending to the said vane to allow for an initial air slippage, said sloping relation decreasing toward the delivery end of the conduit to provide for decreased air slippage.

6. A liquid fuel burner for supplying a mixture of liquid fuel and air to be burned in a combustion chamber, said burner comprising a tubular air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a. liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically dis-- posed vanes extending lengthwise on the inner wall of said; conduit, each vane having a substantially uniform pitch and height, the contourof each vane progressively varying so that the air rotating effectiveness increases in the direction from its air receiving end toward its delivery end.

7. A liquid fuel burner for supplying a mixture of liquid fuel and air to be burned in a combustion chamber, said burner comprising a tubular air conduit terminating in an open mouth, means for forcing air through said conduit, a spray nozzle in said conduit near the open mouth thereof, means for supplying liquid fuel to said nozzle to discharge a liquid fuel spray from the mouth of said conduit, and means for causing an accelerated rotary movement of the air passing through said conduit comprising helically disposed vanes extending lengthwise on the inner wall of said conduit, each vane having a crosssection so changing progressively in the direction away from its air entrance end as to increase its air rotating effectiveness.

RALLSTON' M. SHERMAN.

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