US 3083846 A
Description (OCR text may contain errors)
p 'Z 1963 R. s. WALKER ETAL 3,083,846
scoo FEEDER FOR ROTARY KILN Filed Feb. 17, 1961 INVENTOR$ ROBERT $.WALKER FRED A. MERTZ W W/W *W ATTORNEYS United States Patent 3,083,846 SCOOP FEEDER FOR ROTARY KILN Robert S. Walker and Fred A. Mertz, Allentown, Pa., assignors to Fuller Company, Catasauqua, Pa, a corporation of Delaware Filed Feb. 17, 1961, Ser. No. 90,047 Claims. (Cl. 21418) The present invention relates to the feeding of materials to rotating vessels and is concerned more particularly with the introduction of materials to rotary kilns at a point or points between the ends of the kiln.
It is known in the prior art that peripheral scoops on a rotary kiln have been used to introduce material such as ore and coal to the interior of the kiln. During rotation of the kiln the scoops dip into and pick up material which is held in a bin adjacent the lower parts of the kiln. However, the performance of such scoops has not been entirely satisfactory because of uneven distribution of the incoming material in the kiln contents and consequent lumping and agglomeration in the case of raw material susceptible to such reaction. In the case of coal, coking and fusing may occur.
Where the interior or discharge end of the scoop is flush with the inside of the kiln wall, the material charge in the kiln tends to flow into and even to block the discharge end of the scoop as it passes beneath such charge during kiln rotation. Where the discharge end of the scoop is projected inwardly from the kiln Wall, a portion of the material charge tends to ride along with the scoop as the latter rises from under the charge. The subsequent release or sliding of this portion of the charge from the scoop, traps and buries the incoming material in a single compact mass as it discharges from the discharge end of the scoop, thereby aggravating the problem of agglomeration or fusing of the incoming material into lumps or large masses. Where the discharge end of the scoop has been modified in attempts to alleviate this problem, such as by placing the discharge opening axially of the kiln or by wrapping the scoop about a portion of the kiln wall, the material frequently over-heats before being discharged into the kiln and agglomerates or fuses within the scoop itself. Coal is particularly susceptible to coking and fusion under these conditions.
Accordingly it is an object of this invention to provide a rotary kiln with a scoop which lessens the problem of fusing or coking of incoming materials either in the scoop or in the kiln immediately after being discharged from the scoop.
It is another object of this invention to provide a rotary kiln with a scoop which distributes material, being charged thereby, more evenly within the charge already in the kiln.
Other objects and advantages will become apparent to those having ordinary skill in the art by reference to the following description of a preferred embodiment of the invention.
Broadly, the invention comprises a scoop having a plow-like portion projecting into the kiln which partly rolls back or divides the kiln charge at the point of addition of incoming material and which also is arranged to deliver the incoming material on top of the divided portion, i.e. in what may be termed a furrow, so that subsequent rolling of the charge distributes the incoming material without its being trapped as a single mass by sliding or fall-back of the charge.
In the drawings:
FIGURE 1 is a side elevational view of a rotary kiln provided with peripheral scoops embodying this invention;
FIGURE 2 is an enlarged sectional view taken on line 2-2 of FIGURE 1;
3,033,846 Patented Apr. 2, 1963 FIGURE 3 is an enlarged fragmentary view of a portion of FIGURE 2;
FIGURE 4 is a fragmentary perspective view, partly in section, of a portion of the kiln shown in FIGURE 1.
Referring to the drawings there is shown a rotatable cylindrical kiln 10 having a metal shell 12 lined with an appropriate heat and abrasion resistant refractory material 14, such as fire brick. Several series of uniformlycircumferentially-spaced scoop structures 16 penetrate both the shell 12 and its lining 14 at a number of locations along the length of the kiln 10. Each series may consist, for example, of four scoop structures. The exterior pickup portion of each scoop 16 is of metal boxlike formation having side walls 18, an outer wall 20, and a back wall 22, with the edges of the side and outer walls defining an intake opening 24 facing the direction of rotation of the kiln, as indicated by the arrows in FIGURES 2, 3, and 4 of the drawings. The combination of the outer wall 20 and back wall 22 may be said to be generally L-shaped. As the kiln 10 rotates, the exterior portion of each scoop 16, at the lower portion of its travel, passes through and picks up material from the lower portion of a bin (not shown) which usually is sealed off from the atmosphere and may be, for example, of the type shown in the patent to Newhouse, 1,834,963, December 8, 1931. As each scoop 16 then moves upward- 1y, its exterior portion holds the picked-up material until, at a generally predetermined position in the scoops travel, the material slides into the interior of the kiln through a radial opening 26 in the cylindrical wall of the kiln, such opening 26 being opposed to and generally coextensive with the outer wall 20. The side edges of the opening 26 preferably are formed of sheet metal and are coplanar extensions of the side walls 18 of the exterior pickup portion of the scoop 16, while the leading and trailing sheet metal edges 28 and 30 of the opening 26 are inclined inwardly and rearwardly from the direction of rotation of the kiln 10. The angle A between the back wall 22 and the shell 12 may be modified to control the timing of material delivery, after pickup, from the scoop exterior portion through the opening 26 to the interior of the kiln, i.e., the moment of material delivery can be delayed by decreasing the angle A. In the preferred embodiment of the invention, the angle A is such that material is delivered into the kiln 10 after the inner portion of the scoop structure 16, to'be described next, has passed through the charge within the kiln. Because the exterior scoop portion is of relatively small dimension, circumferentially of the kiln, the pickedup material is retained in such portion through only a relatively small angular movement, during kiln rotation, thereby preventing excessive heating of such material before its discharge onto the charge within the kiln.
The inner or delivery portion of the scoop structure 16 has a pair of metal side walls 32 and a sloping metal wall 34- respectively constituting coplanar extensions of the side and leading edges of the opening 26. The Walls 32 and 34, together with a portion of the interior surface of the kiln, form a duct, conduit or tubular projection extending into the kiln, the inner edges of which define a discharge opening 36 which faces in a direction opposite to the direction of kiln rotation. If desired, the opposed side walls 32 may converge or diverge toward the opening 36 in order to narrow or widen the latter. The side of the sloping wall 34 which faces toward the center of the kiln also is covered or lined with the refractory material 14 to prevent both excessive temperatures inside the scoop structure and abrasion of the metal wall 34. The angle B which the sloping wall 34 and its refractory lining 14 makes with the kiln side wall is sufficiently large to permit material within the kiln to fall off the inner surface of the wall 14, during kiln rotation, before the back wall 22 of the exterior scoop portion reaches a slope sufiicient to allow material to slide out of the exterior scoop portion and be discharged into the kiln through the opening 26, as shown best in FIGURES 2 and 3. The wall 14 not only prevents the kiln charge from blocking the opening 26-but also at least partially shields the latter, and the exterior portion of the scoop 16 and material therein from the internal direct or radiant heat from the interior ofthe kiln.
Referring now to FIGURE 4 it will be seen that the same material 14 used to line the kiln shell 12 is employed, as a filler to occupy the corners between the side walls 32 and theadjacent surfaces of the interior of the kiln. The filler mass on each side of the interior portion of the scoop structure generally forms a three-sided pyramid having one flat side 38 generally coplanar with the edges of the discharge opening 36, i.e., in a plane parallel tothe axis of the kiln. Another side 40 of the pyramid is inclined rearwardly, toward the apex of the pyramid, from the direction of rotation of the kiln and gradually slopes down to the interior surface of the kiln from the side edges of the sloping wall 34. Thus, the pyramidal filler matter and the sloping wall 34 form a sort of plough which, when the kiln charge slides therepast, during kiln rotation, divides the charge into sort of a shallow furrow having gradually sloping sides. Hence, upon continued kiln rotation the incoming material will be discharged'into the furrow and be distributed therealong on top of the material therein. Continued rotation of thekiln 10 will cause those parts of the initial kiln charge on each side of the furrow to roll gradually inwardly to mix with the mass of newly received material without its being trapped as a single mass by sliding or sudden fall-back of the kiln charge.
Modifications of this invention will become apparent to those of ordinary skill in the art upon reading this disclosure. Hence it is intended that the material contained in the foregoing description anddrawings be interpreted as illustrative and not limitative.
What is claimed is:
1. In a rotatable kiln having at least one peripheral scoop. structurelprovided with an exterior pickup portion which connects with the kiln interior through an opening in the kiln wall'for feeding material picked up by the exterior portion into the kiln, the improved construction comprising: means adjacent said opening projecting into the kiln and acting, during rotation of the kiln, to divide and form a furrow in part of the contents of thekiln so that material being delivered through said opening will fall on top of such divided contents and within the furrow, said projecting means comprising tubular means extending into saidkiln from said opening and inclined rearwardly from the direction of kiln rotation, the exterior sides of said tubular means defining plow-like surfaces inclined outwardly and rearwardly from the front 4'3. of said tubular means, as respects the direction of rotation of said kiln.
2. In a rotatable kiln having at least one peripheral scoop structure provided with an exterior pickup portion connecting with the kiln interior through an opening in the kiln wall for feeding material picked up by the exterior portion into the kiln, the improved construction comprising: the exterior pickup portion of said scoop comprising a wall extending outwardly from the kiln adjacent the trailing edge of the opening; a sloping Wall projecting into said kiln from the leading edge of said opening and inclined rearwardly from the direction of kiln rotation, the inclination of said sloping wall and the angle between the kiln wall and the wall extending outwardly therefrom being such that kiln contents which have accumulated on top of said sloping wall during kiln rotation will slide from said sloping Wall during continued kiln rotation before incoming material is dischargedfrom said outwardly extending wall into said kiln through said opening.
3. The structure defined in claim 2 in which the exterior portion is of relatively small dimension circumferentially of the kiln. 4. In a rotatable kiln having at least one peripheral scoop structure provided with an exterior pickup portion connecting with the kiln interior through an opening in the kiln Wall, the improved construction comprising: the exterior portion of said scoop comprising a generally L'-shaped wall which is attached by the end of one leg thereof to the kiln adjacent the trailing edge of the opening with the other leg of said wall acting as a scooping plate during rotation of the kiln; a sloping wall projecting interiorly-into said kiln from theleading edge of said hole and inclined rearwardly from the direction of kiln rotation at an angle such that kiln contents resting on the sloping wall will slide off thereof before material picked up by said L-shaped wall slides through said opening.
5. The structure defined in claim 4 including side wall means joining the lateral edges of said sloping wall with the innersurface of the kiln so as to define a scoop discharge outlet facing in a. direction opposite to that of kiln rotation, the exterior surfaces of said side wall means defining plough-like surfaces inclined and diverging rearwardly, as respects the direction of kiln rotation, from said lateral edges of said sloping wall, whereby during rotation of the kiln part of the contents thereof are divided and material fed into the kiln through said opening is delivered on top of the divided contents by said scoop discharge outlet.
References Cited in the file of this patent UNITED STATES PATENTS 2,812,865 Rohde Nov. 12, 1957