US2669296A - Burner throat with air inlet annulus defined by internally bladed cone - Google Patents

Description

Feb. 16, 1954 T. B. STILLMAN ET AL 2,669,296

BURNER THROAT WITH AIR INLET ANNULUS DEFINED BY INTERNALLY BLADED CONE Filed June 14, 1950 Patented Feb. 16, 1954 BURNER THROAT WITH AIR INLET AN- NULUS DEFINED BY INTERNALLY BLADED CON E Thomas B. Stillman, deceased, late of South Orange, N. J.,' by Eloise B. Stillman, exccutrix, South Orange, N. J.,

Maplewood, N. J.

and Jacob A. Mason,

Application June 14, 1950, Serial No. 167,992 Claims. (01. 1581.5)

The present invention relates in general to the construction and operation of fluid fuel burners, and more particularly," to improvements in the construction and the operation of high capacity liquid .fuel burners utilizing a conical spray of atomized fuel discharging through a burner port into a swirling stream of air.

This invention is directed to a device, in a liquid fuel burner of the general type described, for directing the flow of combustion air through the burner port in a manner improving the mixing action of the entering fuel and air, and thus facilitating rapid and complete combustion of the liquid fuel. The present invention provides an arrangement for attaining sufficient swirl of the large quantity of combustion air required for high capacity burner operation, so that effective mixing of the entering air with-the cone of fuel particles is quickly obtained, ignition and combustion ofthe fuel. A need for better control of the entering Fig. 2 is an elevation view on the line 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a sectional view on the line 3-3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a section through the inner cone illustrating the form of the vanes therein; and

Fig. 5'is a section on the line 55 of Fig. 4.

The invention is illustrated as applied to a liquid fuel burner of the type shown in U. S. Patent No. 2,260,062. The burner is mounted in a circular burner port l0 formed in one of the vertical walls ll of a liquid fuel burning furnace. The port I0 converges inwardly to an intermediate circular throat, and then diverges to the inner or furnace side of wall A metallic port ring 20, substantially shaped as a truncated cone,

' defines the'outer section of the burner port, and

thereby promoting combustion air has developed with increases in burner capacity due to the use of higher fuel supply pressures and more efficient fuel atomizers;

In accordance with the invention, burner port air flow directing means are provided whichare an improvement over the internally bladed cone arrangement of Stillman U. S. Patent No. 2,260,062. Specifically an air flow directing means is provided whereby a greater quantity of combustion air may be delivered through the burner, port and brought into effective mixing relationship with the atomized oil fuel.

The improvement to the burner of the Stillman patent resides in dividing the combustion air flow through the burner port into two'annular concentric-streams which may, for the purposes of this description, be termed primary air and secondary air. This division of the combustion air supply is effected by providing two concentric radially spaced specially shaped cone members in the burner port, each provided with a series of specially shaped and arranged vanes imparting a whirling 'motion' in the same angular direction to-the combustion air passing through the port.

Fora more thorough understanding of the principles of the invention, reference is made to the following description of a typical embodiment of the invention as illustrated in the accompanying drawing.

Inthe drawing:

Fig. 1 is a part sectional and part elevational view of a liquid fuel burner and an associated burner port air admission arrangement embodys he nvgnt na. i

has a flange 2| secured to the metal casing |2 of the furnace wall II by bolts l3 which also secure the flange 4 of a spool member 5 to the cone 20 and easing l2. A second or inner port ring 30, likewise shaped as a truncated cone, is supported within and in spaced relation to cone 20 by studs l6 extending through tubular spacers Exteriorly spaced from casing I2 is an outer casing IS, the casings l2 and I 8 forming a passageway |9 for the flow of pre-heated combustion air from a forced draft fan (not shown) to burner port ID.

A circular cover plate 4| closes an access opening in wall I5 arranged coaxially of and of larger diameter than the burner port I. Plate 4| is provided with a heat protective covering of insulating material 42 held in place by a metallic sheet 43, and is rigidly connected by struts 44 to the outer circumference of an air register ring 45 carried by spool member IS, the parts l5 and 45 forming a continuation of outer cone 20. The passage IS, with rings l5 and 45, forms a means for directing combustion air through the burner port around the discharge end of the burner nozzle.

Cover plate 4| supports a central hub member 46 through which extends a burner barrel 41 having a fuel supply assembly 48 on its outer end and an atomizer head 49 on its inner or furnace end. The atomizing head 49 is preferably of a type producing a conical spray of atomized liquid fuel with the axis of the spray coaxial with the cones 20 and 30.

Concentrically attached to barrel 41 and exteriorly surrounding the atomizer head 49 is an impeller plate 50 shaped asa truncated cone with the base toward the furnace chamber.

:: conical surface of impeller plate 50 has a series The of equally spaced air openings and corresponding deflector plates iii associated therewith.

A circular series of segmental louver blades 55 are pivotally mounted Within the annular space between ring ii; and barrel M by pins 52 and 53. The rotationalaxis of each louver blade is at an oblique angle to the axis of barrel 41, and the lades are adjustable about their axes by means of pinions d engaging a ring gear 56 on a rotatable sleeve 5i. Sleeve 51 is rotated by suitable external mechanism (not shown), such as shown in said Patent No. 2,250,062, to position the louver blades 55 to control the flow of air from passageway it into cones 26 and 30.

Inner cone 3d defines the primary air passage through the burner port. The secondary air passage is defined by outer cone 2!! and inner cone 3G. The cones Eli and 39 are provided with special vanes to and it respectively for imparting a whirling motion to the primary and secondary air streams, the whirling motion being about the axis of burner tube 47 and in the same angular direction as the whirl produced by the impeller deflectors 5|.

Outer cone Ell has a reentrantly curved or bulging portion 22 immediately inwardly of and merging smoothly with flange 2i. Portion 22 merges into a truncated cone shaped main portion 23 which terminates in a truncated cone shaped portion 24. Portion 24 makes a lesser angle to the burner tubeaxis than does portion 23, and is substantially parallel to the outer surface of inner cone 30.

Outer cone 2!! is preferably cast from a suitable temperature resistant alloy, and has a circular series of symmetrically spaced deflector vanes 60 welded or the like to its inner peripher and contacting with the outer periphery of inner cone ea In the illustrated embodiment, fourteen (14) vanes 55 are provided, although a greater number may be used, but, in any event, the number of vanes 6!! should always be greater than the number of vanes on the inner cone. The major portion of each vane' 50" lies in a single plane extending generally at an angle of to the entrance and exit planes of cone 2c, the vanes extending from reentrant surface 22 to points short of the inner or furnace end of cone 2t.

Each vane ii! has a short entrance sectionll parallel to the burner tube axis and smoothly merging with the angularly directed main vane section 52. Thus, the secondary air has its flow direction changed smoothly from parallel to the burner tube axis to an inwardly converging, helical direction to provide a whirling action.

The inner or discharge end of the cone-til is formed with a non-circular flattened periphery, preferably a flat-sided regular polygon. A twelvesided polygon is preferred in the illustrated embodiment, and ring 30 is preferably cast of a suitable temperature resisting alloy. Gone 3% has the circular series of symmetrically spaced defiector vanes l6 welded to its inner periphery and corresponding to the number of sides of the polygon. Each vane m is arranged at a general angle of preferably 85 to the plane of the discharge edge of the cone. The inner edge H of each vane extends from a point on the inner edge of the cone midway of the corresponding flat at an outward inclination corresponding to the peripheral surface of a cone having a base angle, is rounded off at its top, and merges with the outer vane edge 72 which is straight and substantially normal to the corresponding por tion of the cone at a point midway of its length. As indicated in Figs. 4 and 5, the inner edge portion 13 of each vane 10 is bent to provide a slight fillip.

It should be noted that a circle tangent to the radially inner ends of vanes lllhas a diameter less than that of impeller plate 59 which may, in the illustrated example, have a 15 /2 inch diameter, thus approaching the diameter of the furnace end of cone 30'. Vanes 10 thus act as a limit for the permissible movement of atomizer head 49 and impeller 50 toward the furnace, the atomizer and impellerthereby being positioned atall times toward the wind box or outside of the vanes 10.

In the operation of the described burner, the air passingthrough impeller 50 has a swirl imparted thereto for effective mixing with the whirlingconical spray of liquid fuel directed from atomizer 69. The outer portion of the air stream through impeller'fiil passes through the primary air passages'formed by cone3ll andvanes 10, being mixed therein with the primary air entering cone'20 beyondthe periphery of impeller" 50.

A whirling motion is imparted to the air passing through cone 30, for eifective mixing of the air with the fuel stream. At the same time, the secondary air passing through the secondary air passages, formed bycones!!! and 30 and vanes 60, has a large degree of swirl imparted thereto. The secondary airentering these passages has its'pressure somewhat reduced and its velocity increased as it passes from the relatively large cross sectional entrance areas of the secondary air passages into the gradually constricted secondary air passage portions formed by "convergence-of outer cone portion 23 toward cone 30. The-high velocity whirling motion of'the secondary air leaving the furnace'end of cone 2fl results in'a further effective mixture of the'secondary" air with the rmixe'd primary air and liquid fuel;

cone.

The mixing of the air with the fuel thus takes place in three steps. First, the air passing through impeller 50 is effectively mixed with the fuel cone. Next, the primary air delivered'from inner cone 3|! is mixed with the air-fuel mixture. Finally, a large supply of whirling secondary air is admixed with the fuel-air mixture entering the furnace; thus, a large quantity of combustion air is :given a degree of swirl sufficient to assure effective mixing with the fuelfor quick combustion. The division of the air into primary and secondary air streams assures better control of the air and better mixing, as neededfor higher oil pressures with more .eflicient atomizers.

While a specific embodiment of the invention has'been shown and described in detail to illustrate the 'application' of the invention principles, it will 'be understood that the invention may be embodied otherwise without departing from such principles.

We claim:

1. Incombination with a furnace" wallrhaving a fuel burner port therein and a liquid fuel burn er nozzle constructed to discharge a stream of liquid fuel through said burner port; meansfor directing a portion of thecombustion air immediately around the dischargeend' of said burner nozzle nad through the burner port; means disposed in the burner port and adividing the remainderof thecombustion-air into a primary air streamrhaving' a substantiallyicircular cross section at its-exit from the portyand an annular secondary air stream, said means-comprising a first; truncated cone shaped port. ring member disposed within the burner port and a second truncated cone shaped ring member mounted concentrically around the first ring member and defining the peripheral surface of the burner port; said first ring member forming a primary air passage embracing the fuel stream and being smaller in diameter than said second ring member to form therewith a secondary air passage embracing the primary air passage; a first series of deflector vanes on the inner surface of said first ring member; a second series of deflector vanes extending between and jointly engaging the facing surfaces of each of said members; and each of said deflector vanes being arranged to extend at an oblique angle to the planes of the discharge ends of said members; and means limiting inward movement of the burner nozzle to a position in which its discharge end is located completely outwardly of said vanes and truncated cone shaped members.

2. In combination with a furnace wall having a fuel burner port therein and a liquid fuel burner nozzle constructed to discharge a stream of liquid fuel through said burner port; means for directing a portion of the combustion air immediately around the discharge end of said burner nozzle and through the burner port; means disposed in the burner port and dividing the remainder of the combustion air into a primary air stream having a substantially circular cross section at its exit from the port, and an annular secondary air stream, said means comprising a first truncated cone shaped port ring member disposed within the burner port and a second truncated cone shaped ring member mounted concentrically around the first ring member and defining the peripheral surface of the burner port; said first ring member forming a primary air passage embracing the fuel stream and being smaller in diameter than said second ring member to form therewith a secondary air passage embracing the primary air passage; a first series of deflector vanes on the inner surface of said first ring member; a second series of deflector vanes extending between and jointly engaging the facing surfaces of each of said members; each of said deflector vanes being arranged to extend at the same oblique angle to the planes of the discharge ends of said members, and the number of vanes in said second series being substantially greater than the number of vanes in said first series; and means limiting inward movement of the burner nozzle to a position in which its discharge end is located completely outwardly of said vanes and truncated cone shaped members.

3. In combination with a furnace wall having a fuel burner port therein and a liquid fuel burner nozzle constructed to discharge a stream of liquid fuel through said burner port; means for directing combustion air around the discharge end of said burner nozzle and through the burner port; means disposed in the burner port and dividin the remainder of the combustion air into a primary air stream having a substantially circular cross section at its exit from the port, and an annular secondary air stream, said means comprising a first truncated cone shaped port ring member disposed within the burner port and a second truncated cone shaped ring member mounted concentrically around the first ring member and defining the peripheral surface of the burner port; said first ring member forming a primary air passage embracing the fuel stream and being smaller in diameter than said second ring member to form therewith a secondary air passage embracing the primary air passage; 2. first series of deflector vanes on the inner surface of said first ring member; a second series of deflector vanes extending between and jointly engaging the facing surfaces of each of said members; the inner portions of each of said defiector vanes being arranged to extend at an oblique angle of substantially 35 to the planes of the discharge ends of said members; and means limiting inward movement of the burner nozzle to a position in which its discharge end is located completely outwardly of said vanes and truncated cone shaped members.

4. In combination with a furnace wall having a fuel burner port therein, an oil burner nozzle constructed to discharge a stream of atomized oil through said burner port, and a truncated cone shaped impeller plate mounted on said nozzle; means for directing a portion of the combustion air immediately around the discharge end of said burner nozzle and through the burner port; means disposed in the burner port and dividing the combustion air into a primary air stream having a substantially circular cross section at its exit from the port, and an annular secondary air stream, said means comprising a first truncated cone shaped port ring member disposed within the burner port and a second truncated cone shaped ring member mounted concentrically around the first ring member and defining the peripheral surface of the burner port; said first ring member forming a primary air passage embracing the oil stream and being smaller in diameter than said second ring member to form therewith a secondary air passage embracing the primary air passage; a first series of deflector vanes on the inner surface of said first ring member; and a second series of deflector vanes extending between and jointly engaging the facing surfaces of each of said members; each of said deflector vanes being arranged to extend at an oblique angle to the planes of the discharge ends of said members; the radially inner ends of the vanes of said first series extending radially inwardly of the impeller plate periphery whereby said first series of vanes limits movement of the nozzle and impeller plate inwardly of the burner port.

5. In combination with a furnace wall having a fuel burner port therein and a liquid fuel burner nozzle constructed to discharge a stream of liquid fuel through said burner port; means for directing combustion air around the discharge end of said burner nozzle and through the burner port; means disposed in the burner port and dividing the combustion air into a primary air stream having a substantially circular cross section at its exit from the port, and an annular secondary air stream, said means comprising a first truncated cone shaped port ring member disposed within the burner port and a second truncated cone shaped ring member mounted concentrically around the first ring member and defining the peripheral surface of the burner port; said first ring member forming a primary air passage embracing the fuel stream and being smaller in diameter than said second ring member to form therewith a secondary air passage embracing the primary air passage; a first series of deflector vanes on the inner surface of said first ring member; each of said deflector vanes being arranged to extend at an oblique angle to the planes of the discharge ends of said members; a second series the burner axis and an exit section lying in a 5 plane radial to the burner but at an oblique angle to the plane of the entrance section.

ELOISE B. STILLMAN. Executrix of the Estate of Thomas B. Stillman,

deceased.

JACOB A. MASON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Irish Apr. 10, 1928 Braine et a1. May 31, 1932' Stillman Oct. 21, 1941 Haynes Feb. 3, 1942' Mason Mar. 19, 1946

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