US2759460A - Directional-flame burner - Google Patents

Description

4 Sheets-Sheet 1 Filed July 19, 1952 m? NT Q .m 3 w m N Qm R. 5N Om RV Q m wv 0m V WM 0 Q o \v NM. 7 o '1 mm, a m z INVENTOR OLL/SON CfiH/G BY M ATTORNEY Aug. 21, 1956 o. CRAIG DIRECTIONALJ'LAME BURNER 4 Sheets-Sheet 2 Filed July 19, 1952 INVENTOR OLL/SON CRA/q m X 4M ATTORNEY Aug. 21, 1956 o. CRAIG 2,759,460

' DIRECTIONAL-FLAME BURNER Filed July 19, 1952 4 Shets-Sh eet 5 INVENTOR Oz. 1. lso/v CRA/G BY W154i ATTORNEY Aug. 21, 1956 o. CRAIG 2,759,460

DIRECTIONAL-FLAME BURNER Filed July 19, 1952 4 Sheets-Sheet 4 INVENTOR 01.4 lso/v 61mm ATTORNEY United States Patent DEREQTIONAL-FLAME BURNER Ollison Craig, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Mars sachusetts Application July 19, 1952, Serial No. 299,888

3 tilaims. (Cl. 122-333) This invention relates to directional-flame burners and more particularly to fuel burning apparatus for use in the furnace of a steam generating unit.

In the burning of fuel for the generation of steam it is often desirable to provide for adjusting the direction of the flame. This is particularly true in the burning of fuels burned in suspension where the fuel and air are projected into the combustion chamber with great force, so that the flame is very long. By adjusting the direction in which the flame extends, it is possible to control superheat, among other things; the adjustment of the flame to various directions in a vertical plane will change the temperature of the gases which pass into the convection passes of the boiler. Changing the direction of the flame also produces a change in the manner in which the products of combustion swirl and flow in the combustion chamber. Burners have been used in the past in which the flame produced is adjustable angularly, but these prior-art devices have suffered from many disabilities. For one thing, they cannot be used without disturbing the water-wall tubes in the furnace wall; bending the tubes to provide an opening for the burner is expensive and deprives the furnace wall of a large radiation area. Also, the previously known burners of this type have been very expensive, a particularly undesirable feature in installations where the burner is only intended for intermittent use as an auxiliary to separate burners using other types of fuel. In many cases the mixing is poor, resulting in poor combustion and low efficiency as well as smoking. Also, many of these devices may lose ignition during changes in flame direction. The present invention obviates the shortcomings and the difiiculties encountered in the prior art in a novel manner.

It is therefore an outstanding object of the present invention to provide a directional-flame, intertube burner which is simple in construction and inexpensive to manufacture.

Another object of the invention is the provision of a fluent fuel burner in which mixing of the fuel and the combustion air is very thorough.

A further object of the instant invention is to provide an intertube burner which permits adjustment of the length and angular direction of the flame.

Another object of the invention is the provision of a burner for fluent material which permits changes of angularity of the flame without danger of loss of ignition.

A still further object of the invention is the provision of an intertube burner which is very rugged and which will give a long life of useful service.

It is another object of the invention to provide an intertube burner which permits the burning of a number of fuels in the same portion of the furnace.

A further object of the present invention is the provision of an intertube burner in which the water wall tubes of the furnace are only slightly disturbed and are subject to very little loss of radiant heat from the furnace because of rearrangement.

Another object of the invention is the provision of a'di- 2,759,460 Patented Aug. 21, 1956 rectional-flame burner construction wherein vanes controlling the gas flow can be located between the tubes and rigidly supported in that position.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms, as illustrated by the accompanying drawings in which:

Figure 1 is a vertical sectional view of a burner embodying the present invention taken centrally thereof and longitudinally of the furnace,

Figure 2 is a vertical elevational view of the burner looking from within the furnace,

Figure 3 is a horizontal sectional view slightly reduced in size of a portion of the burner taken on the line 3-3 of Figure 2,

Figure 4 is a vertical elevational view of the burner showing its external appearance when looking toward the furnace,

Figure 5 is a view of a mechanism used with the burner as it appears when looking along the line 55 of Figure 2, and

Figure 6 is a vertical sectional view of a modification of the invention.

Like reference characters denote similar parts in the several figures of the drawings.

For the purposes of the discussion which follows, the portion of the furnace wall in which the apparatus resides will be thought of as the front wall, so that the expression longitudinal will mean perpendicular to the wall, the expression transverse will mean parallel to the wall, the expressions inner or forward will mean toward the inside of the furnace wall, and the expressions outer or rearward will mean toward the outside of the wall. This is not meant to imply, however, that the burner could not be used as Well in connection with the other walls of the furnace.

Referring first to Figure 1, wherein is best shown the general aspects of the invention, the burner, generally designated by the reference character 10 is shown in use with the water wall tubes 11 of the furnace of a steam generating unit. Although the furnace wall is not shown, it is to be realized that the water wall tubes normally reside in side-by-side relation on the inside surface of the wall and that an opening in the wall must be provided for the apparatus of the invention. In the present embodiment of the invention, two vertical water wall tubes 11 are bent rearwardly and laterally to form vertically elongated openings or slots 12 (see Figure 2). The two tubes so bent reside behind a third tube which is not bent, so that in the area of the burner and of the opening in the furnace wall, the water wall tubes are arranged in rows of three aligned longitudinally of the furnace. At the upper and lower extremities of the opening in the furnace wall are provided transverse channels 13 and 14. These channels are rigidly connected to the tubes 11 by means of clamp members 15. The clamp members are arranged in pairs, each pair embracing a row of tubes 11; the facing surfaces of each pair are formed with vertical cylindrical grooves 16 (see Figure 3). A pair of opposed grooves 16 embrace each tube and a bolt 17 is provided to join each pair of members 15 in clamping relation to the rearward two tubes 11. The forward end of each clamp member is provided with a horizontal medial slot 18 and the portions of the member which lie above and below this slot are joined to similar portions of the opposing member by bolts 19 and 20, respectively. The rearward end.

of each clamp member 15 is bolted to its respective channel 13 or 14. On opposite sides of the burner reside vertical side plates 21 which are fastened to the channels 13- 3 and-.14 and extend forwardly to the inner edge of the opening in the furnace wall. There is a pair of clamp members associated with each row of tubes 11 across the top and bottom of the burner, the two transverse rows of clamp members thus being coextensive with the channels 13 and 14. Between the bottom pair of clamping members and the top pair associated with each row of tubes 11. are situated a series of generally similar clamp members 22 which differ from the members 15 only in that their rearward endsare notconnected to structural members and are formed to present a smooth, rounded surface to the flow offuel. The clamp. members 22 are similar to the clamp members 15 in that they are provided with slots 23 and each pair is held together by bolts to embrace the three tubes which extend therebetween. The upper and lower edges of the clamp members 15 and 22 are formed with semi-circular notches 24, each notch cooperating with a similar notch onthe adjacent clamp member to form a circular aperture, extending horizontally through the rows of clamp members. Through these apertures are passed the shafts 25 of adjustable vanes 26 which may have a longitudinal slot entering the forward edge In the present embodiment, three slots 12 are provided between the Water Wall tubes and a vertical row of three vanes resides in each of the outer two slots; in the center slot, however, there are only two vanes, one in the upper portion and the other in the lower portion. The purpose of the omission of a vane in the central portion of the burner is to permit the insertion of a supplemental burner, as will be described hereinafter. The shafts 25 on which the vanes are mounted are connected together for simultaneous movement in a manner which will be described more fully hereinafter.

Extending rearwardly from the rear ends of the clamp members is a tubular mixing housing 27 of square crosssection, defining a mixing chamber 28 the forward end of which fits snugly into the square opening defined by the channels 13 and 14 and the side plates 21. The forward edges of the housing are welded or otherwise secured to the channels 13 and 14 and the side plates 21. Into the rearward end of the housing is snugly fitted a short tube 29 of circular cross-section, the diameter of the tube being of such a size that the sides of the housing 27 are tangential to the wall of .the tube at four points in its circumference. The tube 29 is capable ofsliding movement in and out of the housing 27 and is held in a selected position by set screws. or the like, not shown. Since the tube 29 is of circular cross-section while the housing 27 is of square cross-section, fourfillers 34) are provided to fill the areas in the corners of the housing which lie outside the. axialprojection of the tube into the housing. Mixing vanes 31 are welded to the tube 29 and extend inwardly thereof; these vanes are arranged generally helically of the axis of the tube. Fastened to the rearward end of the housing 27 completely surrounding the tube 29 is a secondary air housing 32 of generally box-like configuration; the housing 32 is provided with a square opening in the forward side, the edges of which are welded or otherwise fastened to the rearward end of the mixing housing 27. The upper side of the housing 32 is open and is connected to a source of secondary air, not shown, in a wellknown manner. Residing within the housing 32. near the upper opening are secondary air vanes 33 mounted on horizontal transverse shafts 34 the ends of which are keyed externally of the housing. 32 to crank arms 35 which, in turn, are pivotally connected to an actuating bar 36. The actuating barv 36 extends rearwardly of the housing. and is pivotally connected to a crank arm 37 which is keyed at its other end to a shaft 38 which is journaled-to the rearward external surface of the housing. The shaft 38 is keyed to the vertexof a gear segment 39 which is actuated by a worm 40 which is rotated by a hand wheel 41. A seriesof peep holes, 42 enter the reaward side of the housing 32 and-are spaced about the axis of the tube 29.

A cir cula 1: opening 43 vis formed-,inthe rearward side of the housing 32concentrically with the axis of the tube 29. In this opening 43 is fastened one end of a tubular flange member 44 which extends rearwardly for some distance. To the other end of the flange member id is fastened a fuel housing 45 which consists of a generally tubular portion coaxial with the tube 29 and another tubular portion which extends at a right angle thereto. Generally speaking, one end of the coaxial tubular portion constitutes the outlet and is fastened to the flange member, While the outer end of the non-coaxial tubular portion is the inlet and is fastened to a source of fuel, not shown. Within the housing 45 and arranged around the axis of the tube 29 is a series of vanes 46 which are mounted on shafts 47 which extend parallel to the axis. The shafts 47 are mounted on and extend through the rearward surface of the housing 45 and are provided with means, such as nuts 43, for locking the vanes in selected positions of adjustment. Extending through this same side or wall of the housing 45 and mounted thereon is an auxiliary burner, such as the igniter 49. This igniter resides concentrically of the axis of the tube 29 and extends throughout the entire length of the burner, ending between the rows of water wall tubes 11. Its rearward end resides externally of the housing 45, as has been stated, and is provided with suitable connections for oil, gas, or the like. A tube 50 of circular cross-section extends from the inner surface of the flange member 44 to a position adjacent the vanes 31 in the tube 29. The tube 50 is concentric with the igniter 49 and at the forward end, in the annular space between the tube and the igniter, are fastened helical fuel spreading vanes 51.

Referring to Figure 4, it can be seen that the external appearance of the invention is articularly well shown. The arrangement of the shaft 38 transversely across the front of the housing 32 is shown as well as its connections with the crank arm 37 and the actuating bar 36. The hand wheel41 is mounted for easy access. This view shows the arrangement of the peep holes 42 around the housing 45 and it also shows the concentric arrangement of the vane shafts 47' and their nuts 43. This view shows clearly the relative transverse extents of the housing 32 and the actual burner area, as represented by the channel 14.

An examination :of Figure 2 indicates that, because of the presence of the igniter 49, it is not possible to use a single shaft in mounting the central horizontal row of vanes 26. For that reason, individual stub shafts 52 and 53 are. mounted in each of the side openings 12, each such shaft supporting one vane 26. However, this arrangement necessitates a means for rotating the shaft 53; this is because all the other shafts extend from a common side of the burner, but the shaft 53 extends only from the opposite side of the burner from said common side (the right hand side in Figure 2). The mechanism used to rotate the shaft 53 at the same time as the other shafts 25 and 52 is shown in Figure 2, but is best shown in Figure 5. Anactuating crank arm 54 is keyed to the outer end of the stub shaft 52 and is provided with an aperture 55 at its outer end for attachment to a power cylinder or like actuating .device. The shafts are shown passing through bearing blocks 56 attached to the side plate 21. Keyed to the shaft 52 between the crank arm 54 and its bearing block are two crank arms 57 and 58. Keyed to the outer ends of the upper and lower vane shafts 25 are crank arms 59 and 60, respectively. The crank arm 58 is operatively joined to the crank arm 59 by an arcuate connecting link 61, while a similar connecting link 62 joins the crank arm 57 to the crank arm 60. Referring again to Figure 2, the upper vane shaft 25 is operatively joined to the stub shaft 53 through the medium of a crank arm 63 keyed to the shaft 25, a crank arm 64 keyed to the shaft 53 anda connecting link 65 joining the outer ends of the crank arms 63 and64.

The operation of the apparatus of the invention will be evident from the above description. The igniter 49 is fired in preparation for the introduction of the fuel to the main burner. The secondary air vanes 33 are opened to a desired setting and the air flows into the housing 32 and enters the rearward end of the tube 29 and flows forwardly therethrough. The secondary air strikes the vanes 31 and they are forced into a swirling motion. The fuel, such as pulverized coal, is introduced into the housing 45 along with the proper amount of primary air. The vanes 46 tend to introduce a swirling motion about the igniter 49 within the tube 50 and to promote proper mixing of fuel and air. The fuel moves forwardly through the tube 50 and strikes the fuel spreading vanes 51. In the chamber 28, therefore, the secondary air which is in a swirling condition and moving forwardly is mixed with the fuel and primary air which is not only swirling, but has a definite radial motion in addition to its motion toward the furnace. By the time they reach the vanes 26, the fuel, primary air and secondary air are thoroughly mixed. The mixture passes over the vanes 26 and burns inside the furnace. The amount of inclination of the vanes 26 to the axis of the burner determines the inclination of the center line of the flame to the horizontal and, at the same time, influences the shape, length, and luminosity thereof. When it is desired to change a quality of the flame, for instance, the inclination or tilting, it is only necessary to adjust the vanes 26. In the burning of pulverized coal, it is necessary to present an inclined plane and edge to the fuel flow in order to maintain ignition. This is probably because of the vortex formed by the passage of a gas or fluid over such an edge. In any case, the present apparatus is arranged with the various rows of vanes which reside at different angles in the intermeo diate position of the flame. In Figure 1, which shows the position of the vanes when the flame is directed generally horizontally, it can be seen that the upper row is inclined upwardly, while the lower row is inclined at an equal angle downwardly. The intermediate row 66 extends more or less horizontally. When the flame is directed upwardly at its greatest angle, the vanes are all parallel and directed upwardly; when the flame is directed downwardly at its greatest angle, the vanes are also parallel and directed downwardly. This means that means is provided for moving the shafts on which the vanes are mounted at different rates of rotation. When the flame is being moved within the range from the intermediate position to the uppermost position, the intermediate vanes have a greater angular change to make, while the lower vanes have an even greater angle to travel through; the rates of rotation of the respective shafts are in a corresponding ratio. The same situation exists in the range from the intermediate position to the lowermost position, the rates of rotation in this case being exactly reversed, of course. The net result is that, when the vanes are moved from one setting to another in order to change the direction of the flame, there is never a time when all the vanes extend horizontally and parallel to the flow of fuel and air in the chamber 28; this means that there is always a set of vanes which are inclined to the flow and which will retain ignition. When it is desired to change the setting of the vanes 26, it is only necessary to move the actuating crank arm 54 a sufficient amount. To move the vanes upwardly, the crank arm 54 is moved in a counter-clockwise direction (Fig. and this produces a certain angular rotation of the stub shaft 52 and produces in the range from intermediate to uppermost position of the flame a somewhat lesser rotation of the upper shaft 25 through the medium of the crank arm 58, the connecting link 61, and the crank arm 59. A somewhat larger rotation of the lower shaft 25 is brought about through the crank arm 57, the connecting link 61, and the crank arm 60. The rotation of the upper shaft 25 produces an angular rotation of the stub shaft 53 equal to that of the shaft 52 through the medium of the crank arm 63, the connecting link 65, and the crank arm 64.

Referring next to Figure 6, wherein is shown a modified form of the invention, the burner 110 is shown in use with the water wall tubes 111 of a furnace. Supporting channels 113 and 114 extend above and below, respectively, the general burner area. Upper and lower rows of clamping blocks 115 are fastened to the water wall tubes by means of bolts 117, 119 and 120, there being slots 118 between the latter two bolts. Vertical side walls 121 extend between the channels 113 and 114, while the clamping blocks are also fastened to the said channels. Intermediate clamping blocks 122 are supported only by being clamped to the water wall tubes, but are provided with generally horizontal slots 123. Each intermediate block is provided at its rearward portion with a separable block bearing 124 in which are rotatably mounted the shafts 125 of vanes 126. Each vane 126 is of generally airfoil cross-sectional shape and is mounted along its rearward edge on the respective shaft 125. It is to be noted that the slots 118 and 126 in the blocks 115 and 122, respectively, are formed discontinuously and are made up of a series of surfaces arranged at various angles with respect to each other. In the same way, the adjacent upper and lower edges of the blocks are formed with the same zig-zag conformation, as is evident from the drawing. The remainder of the present embodiment of the invention is substantially like that of Figure 1. A housing 127 extends rearwardly from the channels 113 and 114 and the side plates 121 and merges with a secondary air housing 132. The housing 132 has vanes 133 mounted and controlled in the manner shown in connection with the embodiment of Figure 1. A fuel housing extends rearwardly from the secondary air housing 132 and is operatively joined to the interior of the housing 127 by means of a tube 150. Vanes 146 control the flow of fuel and primary air through the housing 145. The operation of this embodiment is substantially like that of the burner of Figure 1. In the present embodiment, it is possible to replace the vanes 126 if they become worn by merely removing the housing 127 and unbolting the bearing blocks 124, whereupon the shafts 125 and the vanes 126 can be removed and replaced. Also, the zig-zag conformation of the slots 118 and 123 and the spaces between the adjacent blocks does not allow leakage of fuel, such as pulverized coal, through passages which are not under the control of the vanes 126. Instead, the coal will pack into these spaces and form a hard seal, so that fuel flow must take place through the main passages and be controlled by the vanes. The aforementioned slots and spaces are, of course, necessary because of the growth at elevated temperatures of the material from which the blocks are formed.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having thus been described, what is claimed as new and desired to secure by Letters Patent is:

1. In combination with a furnace wall having an opening therethrough, a row of spaced upright water wall tubes adjacent the furnace side of the wall, certain of the tubes crossing the opening and being arranged parallel to one another in groups, a vertical plane which passes through the tubes in a group being perpendicular to the furnace wall, there being at least two closely-spaced tubes in each group, the groups being spaced apart to provide a plurality of vertically-elongated slots, means to deliver air and fuel forwardly through the opening to the said slots and thence through the slots into the furnace, a block on each side of each group of tubes, blocks on opposite sides of the same group being joined for clamping the group therebetween, bearings associated with the blocks, horizontal shafts mounted in the bearings, and vanes residing in the slots and mounted on the shafts.

2. In combination with a furnace wall having an opening thereth-rough, a row of spaced upright water wall tubes adjacent the furnace side of the wall, certain of the tubes crossing the opening and being arranged parallel to one another in groups, a vertical plane which passes through the tubes in a group being perpendicular to the furnace wall, there being at least two closely-spaced tubes in each group, the groups being spaced apart to provide a plurality of vertically-elongated slots, means to deliver air and fuel forwardly through the opening to the said slots and thence through the slots into the furnace, vanes residing in the slots, horizontal shafts on which the vanes are mounted, means for actuating the shafts, the vanes being mounted on the shafts in such a manner that at no time are all the vanes simultaneously parallel to the direction of approach of air and fuel to the vanes, two blocks arranged one above the other on the same side of a group of tubes and partially embracing the tubes, a bearing formed in the adjacent edges of the blocks, a horizontal shaft mounted in the said bearing.

3. In combination with a furnace wall having an opening therethrough, a row of spaced upright water wall tubes adjacent the furnace side of the wall, certain of the tubes crossing the opening and being arranged parallel to one another in groups, a vertical plane which passes through the tubes in a group being perpendicular to the furnace wall, there being at least two closely-spaced tubes in each group, the groups being spaced apart to provide a plurality of vertically-elongated slots, means to deliver air and fuel forwardly through the opening to the said slots and thence through the slots into the furnace, vanes resting in the slots, horizontal shafts on which the vanes are mounted, means for actuating the shafts, the vanes being mounted on the shafts in such a manner that at no time are all the vanes simultaneously parallel to the direction of approach of air and fuel to the vanes, a block fastened to one side of a group of tubes and partially embracing the tubes, a bearing formed on the portion of the block away from the furnace, a horizontal shaft being mounted in the bearing.

References Cited in the file of this patent UNITED STATES PATENTS 639,437 Robinson Dec. 19, 1899 1,852,809 Kleinow Apr. 5, 1932 1,957,965 Kennedy et a1. May 8, 1934 2,011,026 Bailey et a1 Aug. 13, 1935 2,229,068 Frisch Jan. 21, 1941

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