US3472422A

US3472422A - Shaft kiln discharging mechanism

Info

Publication number: US3472422A
Application number: US678029A
Authority: US
Inventors: Joseph J Ruiz
Original assignee: Basic Inc
Current assignee: Basic Inc
Priority date: 1967-10-26
Filing date: 1967-10-26
Publication date: 1969-10-14
Anticipated expiration: 1986-10-14

Description

Oct. 14, 1969 J. J. RUIZ 3,472,422

SHAFT KILN DISCHARGING MECHANISM Filed Oct. 26, 1967 I 3 Sheets-Sheet l I I I INVENTOR JOSEPH .1. RUIZ @MMMd KW ATTOI-iNEYS Oct. 14, 1969 J. J. RUIZ SHAFT KILN DISCHARGING MECHANISM 3 Sheets-Sheet 2 Filed Oct. 26, 1967 INVENTOR JOSEPH J RUIZ l HHIIHIH ATTORNEYS Oct. 14, 1969 J. J. Ruiz SHAFT KILN DISCHARGING MECHANISM 3 Sheets-Sheet 3 Filed Oct. 26, 1967 INVENTOR JOSEPH J. RU/Z ,zrzalg pw zz a KM ATTOR NE YE United States Patent O 3,472,422 SHAFT KILN DISCHARGING MECHANISM Joseph J. Ruiz, Cleveland, Ohio, assignor to Basic Incorporated, Cleveland, Ohio, a corporation of Ohio Filed Oct. 26, 1967, Ser. No. 678,029

Int. Cl. B67d /02 US. Cl. 222-1 23 Claims ABSTRACT OF THE DISCLOSURE A shaft kiln having inlet and outlet means and means to apply heat to the kiln and material passing therethrough. The kiln has a rectangular outlet at the discharge end and a discharge mechanism positioned adjacent the outlet to receive material therefrom. The discharge mechanism is in the form of a prism which reciprocates transversely of the outlet and receives the material as it is discharged from the kiln.

DISCLOSURE This invention relates generally as indicated to a shaft kiln and to a discharging mechanism for such kiln, and more particularly to such a kiln and discharging mechanism whereby uniform downward movement of material passing through the kiln is achieved.

Shaft or vertical kilns of the type to which the present invention relates have generally been known for many years for calcination, sintering or other heat treatment of granular materials such as limestone, magnesite, alumine. and the like. Shaft kilns are usually vertical kilns in which a'charge of material to be treated passes downwardly through the open top of the kiln in countercurrent flow to an upwardly moving stream of hot gas. The temperature of the upwardly moving gases, of course, depends upon the type of material being treated as well as the desired heat treatment.

One problem which is frequently encountered in shaft kilns is that of achieving uniform downward movement of the material at all points within the cross-section of the kiln. The inability to achieve such uniform movement may result in non-uniform heating of the material and uneven processing, which in turn can cause coalescence of the granular material and even clogging of the kiln when such condition becomes exaggerated.

Another problem which is encountered in shaft kilns is that of achieving uniform distribution of combustion of fuel or penetration of heat through the entire kiln cross-section. In attempting to overcome this problem, kilns have been designed of oval cross-section to reduce the distance which the heating gas must travel in order to penetrate the granular material passing through the kiln. Kilns of oval cross-section, although facilitating penetration of the heating gas, do not readily permit uniform movement of the granular material through the kiln or uniform discharge from the kiln outlet.

To overcome the discharge problem, variou discharge mechanisms have been provided in association with the kiln outlet. One such mechanism is a mechanical conveyor illustrated in US. Patent 3,094,016. Another such device is a reciprocating drag bar mechanism shown in US. Patent 3,165,304. These devices are not entirely satisfactory, however, and with the drag bar mechanism particularly, it has been found that some areas of the granular material are hotter than others, which likewise tends to produce uneven processing as well as coalescence of the material.

It is an object of the present invention, therefore, to provide a shaft kiln with a discharge mechanism whereby uniform downward movement of granular material through such kiln is achieved.

Another object of this invention is the provision of a discharge mechanism for shaft kilns and the like whereby coalescence of granular material within such kiln will be avoided.

It is a further object of this invention to provide such a discharge mechanism whereby a uniform discharge of treated material from the kiln will be obtained.

Still a further object of this invention is the provision of a discharge mechanism for shaft kilns which includes means to distribute and cool material as it is received from the outlet of a kiln.

Another object of this invention is the provision of a process for the uniform movement and discharge of granular solids from a vertical kiln.

Other objects, features and advantages of this invention will become apparent to those skilled in the art after a reading of the following more detailed description.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

FIG. 1 is a fragmentary cross-section view of the outlet of the kiln and the discharge mechanism associated therewith;

FIG. 2 is a fragmentary cross-section view of such kiln taken on line 2-2 of FIG. 1;

FIG. 3 is a plan view in section taken on line 33 of FIG. 1;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3; and

FIG. 5 is an enlarged fragmentary view of the stepped prism discharge mechanism of this invention.

Referring to the drawings, a shaft furnace or kiln is designated generally by the numeral 1 and includes an upper inlet (not shown) into which the granular material to be treated is introduced. Such kiln also includes rectangular outlet 2 and a reciprocably movable discharge mechanism designated generally by numeral 3 positioned adjacent the outlet to receive material therefrom. The kiln also, of course, includes a refractory lining 4 on the interior wall and means to apply heat (not illustrated) to the material moving therethrough. The refractory lining gradually slopes inwardly as shown at 4A to accommodate rectangular outlet 2.

The discharge mechanism includes a movable supporting frame 5, discharge plates 6 and a prism 7 of trapezoidal configuration as shown most clearly in FIGS. 2 and 5, which extends to a width substantially equal to the kiln outlet 2. As shown in FIG. 2, the discharge plates extend beyond the kiln outlet sufiiciently to permit the granular solids to form a pile at the natural angle of repose. The discharge mechanism also includes a lower frame 3 which has a conduit 9 and tributory conduits 10 and 11 through which air passes for cooling. As shown more clearly in FIG. 3, the surface of frame 8 has a plurality of apertures 12 distributed thereabout through which air passes at high velocity producing air jets to cool the discharge mechanism and to assist in cooling the granular material.

The discharge mechanism is designed for reciprocable movement transversely of the outlet of the kiln, and this is preferably achieved by a mechanical drive arrangement, such as that illustrated in FIGS. 1, 2 and 3. As thus illustrated, the drive means includes a pair of

eccentrics

15 and 16 which rotate toward center in opposite directions to lessen the thrust on centering roll 17, which is displaced between guide blocks 18 and 19 which are mounted on the movable frame 5. The movable assembly (frame 5, discharge plates 6 and prism 7) is supported by a plurality of

rollers

20, 21, 22 and 23 which are mounted on lower stationary frame 8. It will, of course, be appreciated that any number of such rolls may be provided. The eccentrics are connected through gear reducers 24 and 25 to a main drive motor 26 by a single common shaft 27 which operates through a pulley connection.

The construction of a preferred form of the prism is shown most clearly in FIG. as a stepped prism which comprises a plurality of

steps

30, 31, 32, 33 and 34 and a top tread or substantially fiat surface 35. The longitudinally extending bars which form the stepped prism are spaced as shown to provide a clearance between adjacent bars for the passage of cooling air. The tread 35 has

bars

36 and 37 disposed at an angle thereto substantially equal to the angle of repose to facilitate movement of the material and to provide openings for air flow to the center of the kiln. The bar which extend longitudinally of the prism are supported by a plurality of spaced plates 38 (see also FIG. 1). Because of the stepped prism construction of the discharge mechanism, the granular material will be withdrawn from the kiln at a uniform rate throughout the cross-section.

Although the stepped prism is a preferred form, the prism may be provided without the steps in which

case bars

36 and 37 would be extended and in contact with discharge plates 6. It is to be understood, of course, that such embodiment is within the confines of the present invention.

Because of the greater heat of the granular material as it is received from the kiln outlet, the top tread 35 of the stepped prism is preferably stainless steel, AISI Specification 309. The bars forming the treads of the

steps

30, 31, 32, 33 and 34 are preferably steel such as ASTM A-514, but may also be of a suitable ceramic material if desired. The steps are preferably approximately 1 /2 inches apart in tread and the step height should be approximately twice the average particle size of the granular material being treated, since the particles must fit into the steps to move from one step to another.

The stepped prism also includes end plates 40 and 41 to prevent granular material from being removed at the ends thereof. These plates are angled outwardly toward the periphery of the prism as shown in FIG. 3 at 42 in order to overcome the friction of the granular material against the plates and to permit an even flow of material.

In order to provide the most efficient discharge of material and hence prevent coalescence of material in the kiln, it has been found that the discharge mechanism should preferably be designed so that it will reciprocate a maximum transverse movement of approximately twice the tread width of the steps, which in the preferred form is approximately 3 inches.

As can be readily appreciated from FIG. 2, the material is uniformly withdrawn from the kiln and received by the discharge mechanism in a plurality of zones controlled by the bars of the stepped prism. The granular solids will accumulate on the discharge plates 6 in a pile, shown by the phantom line, at an angle substantially equal to the natural angle of repose and will be discharged laterally from the plates by the reciprocating movement of the discharge mechanism, falling into hopper 45 and into outlet 46. Outlet 46 is of a standard commercially available type for removal of the granular material from the pressurized hopper 45 while preventing the discharge of air an dhence will not be described in further detail.

Other modes of applying the principle of the invention may be employed, change being made as regards the de tails described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a vertical kiln including an upper inlet and a bottom outlet and means to apply heat to said kiln and to a granular material as such material passes therethrough, the improvement comprising a rectangular outlet on said kiln for the discharge of granular material and a discharge mechanism positioned adjacent said outlet to receive material therefrom, said discharge mechanism comprising a reciprocating prism of a width substantially equal to the width of the outlet of said kiln, means adjacent said prism to confine said material within said width, and means associated with said discharge mechanism to reciprocably move said mechanism transversely of said outlet to move uniformly such granular material through said kiln.

2. The kiln of claim 1 wherein said discharge mechanism includes means to cool the same during operation of said kiln.

3. The kiln of claim 2 in which said discharge mechanism comprises a supporting frame positioned beneath said discharge mechanism having conduit means connected thereto and a plurality of apertures in the surface thereof, whereby air may flow through said conduit and through said apertures to effect cooling of said discharge mechanism.

4. The kiln of claim 1 in which said means to confine said material comprises plates on the ends of said discharge mechanism.

5. The kiln of claim 4 in which said end plates are angled outwardly toward the periphery of said mechanism whereby friction of the granular material against said plates is overcome and an even flow of material is permitted.

6. In a vertical kiln including an upper inlet and a bottom outlet and means to apply heat to said kiln and to a granular material passing therethrough, the improvement comprising a rectangular outlet on said kiln for the discharge of granular material and a discharge mechanism positioned adjacent said outlet to receive such material therefrom, said discharge mechanism comprising a reciprocating stepped prism of a width substantially equal to the width of the outlet of said kiln, discharge plates extending therefrom, and means adjacent said prism to confine said material within said width and means associated with said discharge mechanism to reciprocably move said mechanism transversely of said outlet to move uniformly such granular material through said kiln.

7. The kiln of claim 6 in which said stepped prism is of a trapezoidal configuration, and said discharge plates extend beyond said kiln outlet sufficient to permit such granular material to form a pile at the natural angle of repose.

8. The kiln of claim 7 in which said discharge mechanism includes a movable supporting frame for said stepped prism and discharge plates and a stationary supporting frame positioned beneath said movable frame havinr, conduit means connected thereto and a plurality of apertures in the surface thereof whereby air may flow through said conduit and through said apertures to effect cooling of said discharge mechanism.

9. The kiln of claim 6 in which said discharge mechanism is capable of a maximum reciprocable movement of approximately twice the width of the treads.

10. The kiln of claim 6 in which said discharge mechanism has mechanical drive means associated therewith to effect such reciprocable movement.

11. The kiln of claim 6 in which the steps of said stepped prism discharge mechanism are approximately 1 /2 inches apart in tread.

12. The kiln of claim 6 in which the step height of said stepped prism discharge mechanism is approximately twice the average particle size of the granular material passing through said kiln.

13. The kiln of claim 6 in which the treads of said stepped prism discharge mechanism are steel.

14. In a vertical kiln including an upper inlet and a bottom outlet and means to apply heat to said kiln and to a granular material passing therethrough, the improvement comprising a rectangular outlet on said kiln for the discharge of granular material and a discharge mechanism positioned adjacent said outlet to receive such material therefrom, such discharge mechanism comprising a reciprocating stepped prism and discharge plates extending therefrom, and means associated with said discharge mechanism to reciprocably move said mechanism transversely of said outlet, the steps of said stepped prism being spaced to provide a clearance between adjacent steps for the passage of cooling air through said prism.

15. In a vertical kiln including an upper inlet and a bottom outlet and means to apply heat to said kiln and to a granular material passing therethrough, the improvement comprising a rectangular outlet on said kiln for the discharge of granular material and a discharge mechanism positioned adjacent said outlet to receive such material therefrom, such discharge mechanism comprising a reciprocating stepped prism and discharge plates extending therefrom, and means associated with said discharge mechanism to reciprocably move said mechanism transversely of said outlet, the top tread of said stepped prism having bars disposed at an angle thereto substantially equal to the angle of repose to facilitate movement of granular material and to provide openings for air flow to the center of said kiln.

16. The kiln of claim 8 in which said means to confine said material comprises plates on the ends of said discharge mechanism.

17. The kiln of claim 16 in which said end plates are angled outwardly toward the periphery of said mechanism whereby friction of the granular material against said plates is overcome and an even flow of material is permitted.

18. A discharge mechanism for use with shaft kilns and the like having a vertical discharge outlet of Substantial width comprising a reciprocating prism of a width sufficient to extend across the width of said outlet of such a kiln, means adjacent said prism to confine the material within said width and means associated with said discharge mechanism to reciprocably move said mechanism transversely of the outlet of such a kiln.

19. The discharge mechanism of claim. 18 in which said reciprocating prism is a stepped prism of a trapezoidal configuration and includes discharge plates extending substantially laterally therefrom.

20. The discharge mechanism of claim 19 including a movable supporting frame for said prism and discharge plates and a stationary supporting frame positioned beneath said movable frame having conduit means connected thereto and a plurality of apertures in the surface thereof, whereby air may flow through said conduit and through said apertures to effect cooling of said discharge mechanism.

21. The discharge mechanism of claim 20 including plates on the ends thereof to prevent granular material from being removed from said mechanism at such ends.

22. The discharge mechanism of claim 21 in which said end plates are angled outwardly toward the periphery of said mechanism whereby friction of granular material against the said plate is overcome and an even flow of such material is permitted.

23. In a process of heat treating granular solids in a vertical kiln having a vertical discharge outlet of substantial width wherein such solids are moved downwardly through such kiln countercurrently to a heating gas, the improvement comprising uniformly moving such solids through such kiln and withdrawing such solids therefrom in a plurality of zones by reciprocably moving a stepped prism discharge mechanism transversly of said outlet of such kiln while confining such solids within the width of said outlet.

References Cited UNITED STATES PATENTS 2,300,860 1l/l942 Azbe 222-409 X 2,577,315 12/1951 Ellerbeck 222-409 X 3,104,038 9/1963 De Koning 222-409 FOREIGN PATENTS 1,116,700 11/1961 Germany.

ROBERT B. REEVES, Primary Examiner H. S. LANE, Assistant Examiner US. Cl. X.R. 222--146, 409