US2379490A - Air distribution to burners - Google Patents

Description

July 3, 1945.

AIR DISTRIBUTION T0 BURNERS Fiie d Feb. 21. 1942' lllnln 1 INVEN TOR. v *4 2' Thaw we Era er KITTOIFIVEX T. KRUGER 2,379,490

2 Sheets-Sheet 1 I July 3, 1945. r. 'KRUGER AIR DISTRIBUTION TO BURNERS Filed Feb, 21, 1942 ZSheets-Sheet 2 mumfl'r- 7 0 7 14 INVENTOR. 171601101? K711 B Patented July 3, 1945 AIR DISTRIBUTION TO BURNERS Theodore Kruger, Peoria, -Ill., assignor to Combustion Engineering Company, Inc., New York,

3 Claims.

This inventionrelates to pulverized fuel burners and particularly to the means for effecting a uniform distribution of secondary air at the burner tip.

In horizontally disposed pulverized fuel burners the fuel and air mixture is given a rotary movement as it passes through the burner pipe. This rotary movement imparts turbulence to the mixture and causes it to bush out into a flat cone upon entering the furnace. Seen through an observation opening in the wall opposite the burner the flame from a well designed and operated horizontal burner appears to radiate from the bumer center and form an annular disc. Secondary air is admitted to the furnace around the tip of the fuel burner pipe,

Even distribution of fuel and airto a furnace I with horizontal burners is more difficult than with vertical burners because fewer are utilized and hence the streams of fuel entering the furnace from each burner are larger. Further the path of the burning mixture from the mouth of a a burner to the tube bank of a boiler is usually shorter than with vertical firing. Consequently,

the distribution of coal and air over the cross section of the furnace must be accomplished close- Figure 2 is a sectional view on line 2-4 in Fig. 1.

In the drawings, the burner designated as a whole by the numeral I0 is disposed horizontally and its tip l2 projects into an aperture 13 in the furnace wall I4. The burner I0 is cylindrical and provided on its interior with rifling comprising a plurality of helical ribs 16 extending nearly throughout its length. The burner ID has a V0- lute entrance section l8 through which pulverized fuel in flotation in primary airis supplied tangentially to the burner nozzle through a fuel pipe supply 19.

Secondary air is delivered to the tip of burner In from a windbox 20through which the burner projects. The nozzle section of burner I0 .is enclosed in a casing 22 forming an annular cham- (Cl.110 104) the annular chamber '24 is; in communication with windbox 20 through a circumferential port 26 on the wall of casing 22'.- Dampers pivoted on shafts 3| are arranged around the burner and each'is provided with an arm 34 having a pinand slot connection to an operating ring 36. As

ring 36 is rotated clock-wise (Fig. 1) -the dampers 30 separate with respect to one another and opento permit secondaryair to flow around burner l0 and when ring 36 is rotated counter-clockwise the dampers close and reduce the air flow. It has been found that when air enters the windbox '20 in one general direction as downward in Fig. 1 a major part of the secondary air supply enters the annular chamber 24 around burner I0 through the upper part of port 26. Little'air enters around other parts of the burner, as at the lower part thereof. This inequality of air supply through port 26 around the burnerprevails in the travel of the air toward the furnace through the annular chamber 24 and results inan uneven distribution of the secondary air discharging into the furnace around the burner tip l2. This in turn causes an unbalance in the fuel air mixture within the furnace and inefiicient combustion.

According to the invention, a baiile 40 having a conical outer surface 4| extends inwardly from the casing 2i of windbox 20 across the circumferential port 26 in burner casing 22. The inner edge of 'bafile 4|] is substantially in alignment with but spaced from the furnace-side edge of port 26 to provide an annular opening through which the windbox is in communication with the l2. By blocking the direct entry of the air into port 26 from any direction by means of baffie the velocity of the air from that direction is diminished and is no longer effective to cause an excess flow of air from that direction into the burner. Thus, allof the air is then forced to enter port 26 through opening .42 at right thereby substantially equalizing resistance to ai flow into the burner.

What I claim is; v y y 1. In a pulverized fuel burner; a windbox; a

ber 24 surrounding the burner. At its outer end fuel injector pipe projecting horizontally through angles to its direction of flow inwindbox 20 and then caused to make abrupt turn into port 26, v

said windbox; a casing enclosing said pipe to form an annular chamber therearound and having a port formed in its wall extending substantially completely around the fuel injector pipe adjacent the outer end wall of said windbox for admitting air to said chamber; a deflecting sleeve supported within said windbox so as to extend completely across and around said port and spaced from said casing near one end of said port to form an annular opening between said sleeve and casing leading to said port for causing the air stream in said windbox approaching said port to abruptly change its direction before entering said port.

2. In a horizontal burner having a central nozzle pipe for delivering a fuel and air mixture tangentially from the periphery of its tip; means forming a chamber surrounding :said nozzle and having an air inlet port extending substantially completely around said chamber and an annular opening adjacent said .nozzle tip ior delivering additional air for combustion of the fuel to the fuel and air mixture leaving said tip a windbox surrounding said chamber and communicating therewith through said port; and baiiie means supported within said windbox so as to overlie and be spaced radially from said port between said windbox and chamber.

3. In a burner of the horizontal type comprising a central burner pipe for delivering a fuel and air mixture from its discharge end; a casing surrounding said pipe and spaced therefrom to provide an annular air passage therearound formed with an air inletport extending substantially completely around the casing and an annular air discharge opening adjacent the discharge end of said burner pipe; means forming a windbox around said casing communicating with said air passage through said inlet port and through which air under pressure moves in a direction toward one side of said burner; and a deflector sleeve supported within said windbox so as to extend completely across and around said port and spaced from said casing to form an annular opening between said sleeve and said casing for causing the air stream in said windbox -approaching said port to abruptly change its; direction before entering said port.

THEODORE KRUGER.

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