CA1090123A - Split flow material handling system - Google Patents
Split flow material handling systemInfo
- Publication number
- CA1090123A CA1090123A CA288,983A CA288983A CA1090123A CA 1090123 A CA1090123 A CA 1090123A CA 288983 A CA288983 A CA 288983A CA 1090123 A CA1090123 A CA 1090123A
- Authority
- CA
- Canada
- Prior art keywords
- hearth
- floor
- area
- center
- rabbles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
- F27B9/16—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path
- F27B9/18—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path under the action of scrapers or pushers
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B7/00—Coke ovens with mechanical conveying means for the raw material inside the oven
- C10B7/02—Coke ovens with mechanical conveying means for the raw material inside the oven with rotary scraping devices
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Tunnel Furnaces (AREA)
- Gasification And Melting Of Waste (AREA)
- Electric Stoves And Ranges (AREA)
- General Preparation And Processing Of Foods (AREA)
- Electric Ovens (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
This oven system receives material to be pro-cessed on a rotary hearth in an area radially intermediate and spaced from both the center and peripheral edge of the hearth. A rabble system is provided to urge any material on the hearth from the area of deposit to both the center and peripheral edge of the hearth in response to relative rotary motion between the hearth and the rabble system. Discharge openings are provided at both the center and the peripheral edge of the hearth to allow removal of the treated material. In certain instances, by using a plurality of feeds, the material moved to the center of the hearth and the material moved to the peripheral edge of the hearth may be different materials.
This oven system receives material to be pro-cessed on a rotary hearth in an area radially intermediate and spaced from both the center and peripheral edge of the hearth. A rabble system is provided to urge any material on the hearth from the area of deposit to both the center and peripheral edge of the hearth in response to relative rotary motion between the hearth and the rabble system. Discharge openings are provided at both the center and the peripheral edge of the hearth to allow removal of the treated material. In certain instances, by using a plurality of feeds, the material moved to the center of the hearth and the material moved to the peripheral edge of the hearth may be different materials.
Description
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Background of the Invention Field of the Invention The present invention relates to systems and methods especially suited for moving material during thermo-lytic processes in a rotary hearth. More specifically it relates to methods and apparatus for feeding, conveying and discharging coke during a calcining operation.
Prior Art Oven systems utilizing relative rotary motion be-tween a hearth and rabbles have long been used for heating and calcining material. Such systems normally include, for example, a heating chamber including a roof and cylindrical sidewalls, a circular hearth, a rabble system, a mechanism for imparting relative rotary motion between the rabbles and the hearth, suitable means for the admission of to-be-treated material into the oven, and other means for discharging treated material from the oven. Rabble systems have usually included a plurality of rabbles supported above and extending closely adjacent to the floor of the hearth for engaging and advancing the materials thereon from the area of entry to the point of discharge by relative rotary motion between the floor of the hearth and the rabbles.
The motion may be provided either by rotati~ the floor of the hearth while maintaining the rabbles stationary, or revolving the rabbles while maintaining the floor station-ary. Such systems may also include ports for the admission of oxidizing gases, and, if required, combustible gases, and an exhaust system for combustion by-products and spent gases. ~ -In such prior art rotary hearth systems, it is -believed that, the material to be treated has always been admitted either in the area at the center of the hear~th floor and transported by the rabbles to the peripheral dm/
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edge of the hearth for discharge, or admitted in the area of the peripheral edge of the hearth floor and transported by the rabbles to the center of the hearth for discharge.
In such systems, the material to be treated is moved radially in only one direction during the treatment pro-vided, and, in most instances, only one material or mixture of materials can be treated in the system at any given time.
Such systems also have tended to be size and speed limited.
Small hearths have normally been capable of handling only limited amounts of material. Large hearths normally require more rabbles and a high rate of relative motion between the hearth and the rabbles. Where the rate of operation is relatively fast, it has been found to cause undesirable mechanical effects on the material under treatment, such as fracturing or generating of useless fine material. Fast operation also causes mechanical wear and - te~ ar on the equipment.
Calcining in rotary furnaces is taught, for;ex-ample, in U. K. Patent 1,055,857 and U. S. Patent 3,448,012.
U. S. Patents 319,180; 1,503,234; 3,612,497 and 3,~59,172 are typical of the many systems which teach movement of material from the center to the peripheral edge of a hearth. U. S. Patents 3,470,063; 3,475,286; 3,859,172 (noted above), and many others~ teach the flow of matçrial in a rotary hearth from the outer periphery to the center.
U. S. Patent 3,448,012 (noted above) also discloses a rotary hearth in which the material is moved from the periphery to the center in which the gas above the hearth is partitioned, without partitioning the material under-going treatment on the hearth.
U. S. Patent 740,103 is of interest as showing a rabbling system including two series of rabble blades" in which one series of blades may be at an angle to the other dm/ -2-. ~ , .
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series. However, it does not disclose a rotary hearth, it does not disclose feeding material intermediate the two series of rabbles, nor does it disclose the removal of material from the system at both the center and peripheral edge.
U.S. Patents 630,510 and 734,492 disclose rabble systems in which adjacent blades or rabble systems are inclined at an angle to one another to cause a backward and forward shifting of material on the hearth.
With the above in mind, it is the main object of the present invention to provide a system whereby material is received on a rotary floor at a point radially intermedi- -ate and spaced from the center and the peripheral edge of ~ -the floor, and in which a rabble system is provided which simultaneously urges the material from the area of deposit to both the center and peripheral edge of the floor in -~
response to relative rotary motion between the hearth floor and the rabble system.
Another object of the invention is to provide discharge points along both the center and the outer periphery of the floor to permit the simultaneous discharge of material from both points.
Another object of the in~ention is to provide a ~
rabble system whiCh, by relative rotary motion, is capable ~ -of simultaneously urging material to both the center and peripheral edge of the floor.
Another object of the invention is to provide a means whereby two separate materials are deposited at an inner and outer portion of the floor and moved, respect-ively, to the center and outer peripheral edge of thefloor without commingling.
Another object of the invention is to provide a large rotary hearth system which can operate at low speeds, dm/ -3-thus reducing the fracturing of material, the generation of fines and mechanical wear and tear on the equipment.
The foregoing objects and other objects defined herein are accomplished, generally, in a rotary hearth furnace having at least one point for the admission of to-be-treated material, which point is radially intermediate and spaced from both the center and the peripheral edge of the floor of the hearth. The area of the hearth radially inward from the area of material admission will be hereinafter referred to as the "inboard area" of the hearth. The ring shaped portion of the hearth outside of the point of material admission, and surrounding the inboard area will hereinafter be referred to as the "outboard area" of the hearth. Rabbles disposed above the floor of the hearth and capable of relative rotary movement with respect to the hearth are spaced radially outwardly from the center of the hearth. The rabbles are disposed " ~
.
dm/ _4_ - - lu~r)l~3 differently above the inboard area and outboard area of the hearth. The inboard rabbles are disposed to move material on the inboard area of the hearth inwardly toward the center of the hearth toward one or more centrally located discharge openings. The outboard rabbles are disposed to move the material on the outboard area of the hearth toward the outer periphery of the hearth toward one or more peripheral discharge openings. -If desired the floor or rabble system may carry a divider in the vicinity of the point of entry of the material to assist in defining inboard and outboard areas of the hearth.
In one modification, at least two material admission feeds are provided. These feeds can, if desired, be controlled so that different material is fed to the inboard area and to the outboard area of the hearth, thus allowing the simultaneous treatment of two different materials.
In one particular aspect the present invention provides an oven system comprising: a heated chamber including a roof and sidewalls; a substantially round hearth within said chamber, said hearth having a center and having a peripheral edge; a plurality of radially spaced rabbles within said chamber, said rabbles disposed above, but adjacent to, said hearth; means for providing relative rotary motion between said hearth and said rabbles; means for delivering material to said hearth, said delivery means being above said hearth and radially intermediate and spaced from both the center and the peripheral edge of said hearth; a material outlet at the center of said hearth; and a material outlet at the peripheral edge of said hearth; wherein said delivery means serve to define an inboard area and an outboard area on said hearth, the area of said hearth between the center of said -,. .
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hearth and a circumerence transcribed on said hearth by the radius between the centcr of sald hearth and thc delivery means being the inboard area, and the remalning ring area of said hearth radially beyond, the delivery means and sur-rounding the inboard area being the outboard area; and wherein said radially spaced rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said hearth progressively centerward towards the center material outlet and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said hearth progressively outward towards the peripheral material outlet in res.ponse to relative rotary motion between the hearth and the rabbles.
In another particular aspect the present invention provides in an oven of the rotary hearth type including: a heating chamber, said chamber defined by a roof, generally ~
cylindrical sidewalls and a generally circular hearth, said . ~ ~:
hearth having a center and a peripheral edge; a rabble system .
disposed above said hearth; means for providing relative rotary motion between said hearth and said rabble system; means for delivering to-be-treated material to said hearth, said delivery means being located above said hearth; means for removing material from said hearth and heating means to bring the oven to desired temperatures; wherein the improvement comprises, in combination: said material delivery means b.eing located radially intermediate and spaced from both said hearth center and peripheral edge; said material removing means includes at ~ -least one central outlet located at about the center of said :~
hearth and at least one peripheral outlet located at about the peripheral edge of said hearth; and wherein said rabble system includes at least an inboard and an outboard series of ~ -5a-,~
.,~, ~ , , ~, `` i~l301~3 rabbles, each series including a plurality of rabbles, said rabbles having an active face for engaging any material on said hearth during relative rotary motion between said hearth and rabble system, said inboard series of rabbles spaced progressively radially outward from about the central outlet of said hearth to about the radial distance of said material delivery means, substantially each rabble in said inboard series having its active face oriented at an angle to move any material on said hearth with which it makes contact during 10 relative rotary motion progressively inward toward said central outlet, said outboard series of rabbles spaced progressively radially outward from about the radial distance of said material delivery means to about the peripheral edge of said hearth, substantially each rabble in said outboard series having its active face oriented at an angle to move any :~
material on said hearth with which it makes contact during :-.
relative rotary motion progressively outward toward said peripheral outlet.
In yet another particular aspect the present invention 20 provides a material handling system including: a generally :.
circular substantially horizontal floor, said floor having a :~
, :, center and a peripheral edge; a plurality of radially spaced rabbles disposed above, but adjacent to said floor; means : .
for providing relative rotary motion between said floor and rabbles; and means for delivering material to said floor, said delivery means being above said.floor and radially ~
intermediate and spaced from both the center and the ~.
peripheral edge of said floor, said delivery means serving to define an inboard are.a and an outboard area on said floor, 30 the area of said floor, between the center of said floor and a circumference transcribed on said floor by the radius between said center of said floor and the delivery means jl/ ~ -5b-,. ....... .. . .... . . .. . . .......... .. .
~ ~ , . . .. :
:~.0~ 3 oeing the inboard area, and the remaining ring area of said floor radially beyond the delivery means and surrounding the inboard area, being the outboard area; and wherein said rabbles - above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said floor progressively towards the center of said floor and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said floor progressively outward towards the peripheral edge of said floor in response to relative rotary motion between the floor and the rabbles.
In a further particular aspect the present invention provides a process for handling material in a system including -~
a substantially round floor, said floor having a center and a peripheral edge, and a rabble system disposed above said floor, said process including the steps of: providing relative rotary motion between said floor and said rabble system; delivering material to be treated to said floor at an area intermediate both the center and the peripheral edge of said floor; and then in response to said rotary motion, simultaneously moving said material progressively from the area of delivery towards both the center and the peripheral edge of said floor.
Other details, objects and advantages of the invention will become apparent from the following detailed description.
Brief Description of the Drawings Fig. 1 is a diagrammatic top plan view of a rotary hearth according to the present invention.
Fig. 2 is an elevation through center section 2-2 of the rotary hearth according to Fig. 1.
Fig. 3 is a fragmentary sectional view of one modification of the invention.
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'JS~1~3 Fig. 4 is a still further modification of the inventive concept illustrated in tlle previous figures.
Description of the Preferred Fmbodiments The Oven System Reference is now made to the drawings, wherein ' ~' ~
-:
~ 5d-~O'iJ~t~3 like reference characters are employed to designate like parts throughout the several figures. Referring to FIGS. 1 and 2, an oven 10 having roof 12, sidewalls 14 and rotary hearth 16, define torroidal heating chamber 18. Hearth 16 is generally round and includes central opening 20 and peripheral edge 22. Feed bin 24 is located outside of the oven and is connected by means of tube 26 to chute 28 located within the oven. The bottom of chute 28 is located above the hearth to deliver material to the hearth for treatment.
Chute 28 is radially intermediate and spaced from both the central opening 20 and peripheral edge 22 of hearth 16.
Central opening 20 serves as a discharge outlet as does peripheral discharge outlet 32. These outlets are provided in the system to allow the removal of treated material from the hearth.
, For reference purposes, material delivery chute 28 defines an "inboard area" 34 and "outboard area" 36 of hearth 16 divided, for reference purposes in FIG. l by phantom circle 37. "Inboard area" 34 is the ring shaped surface of hearth 16 between central opening 20 and the circumference transcribed on the hearth by the radius ex-tending between the center of hearth 16 and chute 28.
"Outboard area" 36 is the ring shaped portion of hearth 16 which is radially beyond chute 28 and surrounding inboard area 34.
A radially extending depression in roof 12 pro-vides rabble pit 38 in which rabble support 40 is located.
~edge shaped rabble 42 carried by rabble support 40 is located at the same radial distance from the center of the hearth as chute 28. Rabble 42 serves to urge newly delivered material towards the inboard and outboard portion of the hearth, in response to rotation of the hearth in the counter clockwise direction indicated by dm/ -6-the arrow in FIG. 1. Other rabbles are also present in the system. As is art known, each rabble has an active face, not shown, which is oriented to contact and progessively -move material on the hearth in an inward or outward direction. Rabbles 44 carried by support 40 above inboard area 34 of hearth 16 are oriented at an acute angle to the radius of the hearth, thus placing their active faces in an orientation to move material on the hearth with which they come in contact progressively centerward. Inner most rabble 46 which also depends from rabble support 40 is located to plow material off of hearth 16 and into central discharge outlet 20, which leads, for example, to an art known heat boiler and cooler, not shown, In a similar manner, rabbles 48 carried by support 40 above outboard area 36 are oriented with their active faces at an oblique angle to the radius of the hearth to move material with which they come in contact during relative rotary motion progressively towards the periphery of the hearth. Outer most rabble 50 is located to plow material off of the hearth and into peripheral discharge outlet 32. Central discharge outlet 20 and peripheral discharge outlet 32 may feed to common or separate post treatment facilities, as desired.
In general, a space of about 0.5 to 4 inches (1.25 to 10 cm.l is maintained between the bottom of the rabbles and the bed of hearth 16. Rabble support 40 is adjustable, thus allowing an adjustment and variation of the vertical pen-etration of the rabbles into the bed of material under treatment. Additional detaIls of the system and its operation on to-be-treated material are set forth below.
Operation of the System Referring again to FIGS. 1 and 2, the operation of oven system 10 in the calcination of coke, for exa~ple, dm/
, . . .
O~S~3 is now described in detai~. Oven system 10 is pre-heated by art known means, not shown, to a temperature in the range of about 450C to about 1800C, and preferably from about 1000C to about 1550C. Counterclockwise rotation is initiated in hearth 16 by art known means, also not shown. Suitable heating, rotary drive apparatus and other hearth details are disclosed, for example, in U.S.
Patent 3,612,497. To-be-treated delayed petroleum coke having an average particle size of about n . 50 inch (1.28 cm.) and a maximum particle size of about 2 inches (5.8 cm.) is fed from bin 24 through tube 26 into feed chute 28. Feed chute 28 is adjusted so that its lower end is about 6 to 8 inches (15.2 to 20.1 cm.) above rotating hearth 16 to pro- -vide a circumferential band of coke on the hearth overlying - the interface 37 between inboard area 34 and outboard area 36 of the hearth. In the structure shown in FIGS. 1 and 2, wedge-shaped rabble 42 is immediately upstream of chute 28.
After one nearly complete revolution of hearth 16, coke deposited from chute 28 is moved into contact with wedge rabble 42 and caused to divide. A portion of the coke is urged onto inboard area 34 and a portion is urged onto out-board area 36 of hearth 16, the coke thus forming a pair of adjacent concentric windrows. The hearth continues to rotate in a counter-clockwise direction as indicated by the arrow -~
on FIG. 1. After one cornplete additional revolution, the coke urged onto inboard area 34 and outboard area 36 contacts and then begins to build-up against the leading or active faces of the inboard and outboard rabbles 44 and 48 which are next adjacent to wedge rabble 42. As coke piles up against the active faces of rabbles 44 and 48, a portion spills off at the back or trailing edge of each rabble, thus form-ing a pair of further separated windrows, not shown. These windrows are in turn carried around by the continued dm/ - -8-01~
rotation of hearth 16 until they come into contact with the next adjacent radially inward or outward rabbles 44 and 48.
This process is repeated progressively until the material reaches rabbles 46 and 50 at the center 20 and outer periphery 22 of the hearth. Then additional rotation of the hearth forces the material radially inward and outward of the last rabbles 46 and 50, respectively, and into discharge openings 20 and 32.
During the movement of the coke from chute 28 to discharge chutes 20 and 32, the coke is gradually heated.
Heating can be by means of air and combustible gases injected into the furnace by inlets, not shown, and ignited, or by the combustion of volatile combustible gas-es released from the coke as it is heated. In the latter - case, it is still required that air or other oxidizing gases be in~ected into the chamber to support combustion. In the calcining treatment of coke, heat from either form of -combustion in chamber 18 exceeds 2000F tlO93C). The heat in chamber 18 radiates directly onto the material under treatment and is also reflected from roof 12 and side-walls 14 of the oven thus aiding in the heating of the coké on the hearth.
The hearth rotates at a relatively slow rate, about 4 minutes for one complete revolution. Therefore, since repeated revolutions of the hearth are required to cause the coke to be shifted radially inward and outward ~
from rabble to rabble, the entire treating process may -require one hour or more.
Coke treated in this system by this process is calcined into a form of volatile free, dense carbon. It is useful, for example, for the production of electrodes ~ -used in the electrolytic production of aluminum, and in dm/ ~9~
10~ 3 other electrolytic operations.
Utilizing this system, for a given hearth rotating at a given speed, more material can be processed in a given time than is processed in prior art operations in which the to-be-treated material is unloaded at the center of the hearth and moved to the periphery, and vice-versa. This is due to the fact that the critical paramenter for treatment is temperature rather than time. Alternatively, this system per-mits the inboard and outboard half of the hearth to handle half of a normal material load with less material pile-up on rabbles and at a slower rate of revolution. In a similar manner, this system allows the usage of large hearths at relatively slow speeds to provide treatment of a greater amount of material ln a given period of time.
Alternative Embodiments A variety of modifications including those obvious to one skilled in the art are to be included within the scope of the invention as defined in the specification and the claims appended hereto. Referring to FIG. 3 one alterna-tive embodiment of the present invention is shown. In thisversion a pair of feed ohutes 28a and 28b are disposed respectively inboard and outboard of divider 52 carried on the floor of hearth 16. This arrangement allows the amount of material treated on the inboard and outboard sections of the hearth to be controlled. It also allows different materials to be treated on the inboard and outboard portions of the hearth without mixing or comingling them.
Z~e, ' '' I~ modification shown in FIG. 4, the hearth is tilted away from the area of material entry at interface dm/ ~10-'')',~ ' lt~
37a below chute 28 and towards the central and peripheral discharge chutes 20 and 32. In this embodiment, or in art known stepped or terraced versions, not shown, gravitational forces aid the r~bbles in movinq material across the hearth.
Other variations encompassing the present in-vention will be apparent to one skilled in the art. For example, more than one radial array of rabbles may be utilized to either increase stirring or maintain control of the material undergoing treatment on the hearth. The rabbles may be arrayed in other than a straight radial line.
For example, they may affect a spiral or a random pattern.
The only requirement is that each rabble be at the required ;~
angle and that the leading and trailing edge of each ad~
jacent rabble overlap or be sufficiently close to each other adjacent rabble to effectively move the material from the, area of deposit on the hearth to the central and peripheral discharge outlets. -While the spacing between the radially arranged !
rabbles may, if desired, be equal , these spacings may also vary to compensate for changes in the concentric areas of the hearth so as to maintain substantially constant depth of the bed of material across the hearth. For example, ~-~
in order to maintain a substantially constant depth of -material on the hearth, the rabbles disposed above the out~
bo~rd portion 36 of said hearth, progressing outward from j~
material delivery chute 28 to periphery 22 may progressively ; --decrease in spacing to compensate for an increase in the ring shaped area of the portion of the hearth overridden by each respective rabble as it is located farther from the center of the hearth. In a similar manner, the rabbles disposed inboard from said material delivery chute 28 to the center may progressively increase in radial spacing to compensate for a decrease in the ring shaped area of the dm/ -11-:.... , ' ' . - ~ . , - ' - . . . .; -' . -lV~ 3 hearth overridden by each respective inboard rabble as it is located closer to the center of the hearth.
The rabbles themselves may be constructed of high temperature materials, such as steel or mild steel coated with ceramic. They may be cooled by fluids circulating through the rabbles. One especially useful form of rabble is constructed of open grid metal filled with thermally-insuiating ceramic material, and includes a provision for circulating cooling fluids, as described in U.S. Patent 3,740,184.
Other than the fact that it must be spaced from both the edge 22 and center 20 of the hearth, the location of material inlet chute 28 is not critical. In some instances, it may be desirable to locate chute 28 at a point, such that inboard area 34 and outboard area 36 of the hearth are approximately equal. Such a location would be approximately determined by the formula:
r= 2 where; r, is the radial distance of the chute from the center of the hearth, and R, is the radius of the entire hearth.
This formula assumes that the area of central opening 20 is very small increment of the total area of the hearth.
Other factors may dominate the consideration of the location of supply chute 28. If the time of treatment of material on each half of the hearth is critical, then the number, spacing and size of rabbles acting on inboard hearth portion 34 and outbaord hearth portion 36 may be as important or more important than the area of the inboard and outboard portions.
Also, it is art known to utilize multiple supply dm/
. . ~ ' .- . :-lV~lZ3 chutes at either the center or periphery of the hearth, in conjunction with multiple rabble systems, to move a plurality of materials across the entire radius of the hearth, without commingling the materials, to preselected outlets, see U.S. Patent 3,859,172. Such systems may be improved, for example, by locating the multiple supply chutes in areas spaced from both the cçnter and peripheral edge of the hearth, along with multiple rabble systems, in accordance with the teaching of the present invention, to move a plurality of materials selectively to preselected outlets at the center or periphery of the hearth, in accordance with the teaching of the present invention.
In the example shown, the hearth rotates and the rabbles are stationary, and this is indeed the preferred embodiment. However, the present invention contemplates systems in which the hearth is stationary and the rabble system rotates around the center of the hearth.
While this method and apparatus has been shown to be useful, for example, for calcining coke for use in the production of electrodes, it is also useful for the continu-ous calcining, coking and/or devolatilizing of any carbonaceous material, such as non-coking coal,anthracite -coal, briquettes or pellets containing bituminous coking coal, green petroleum coke, wood products and other similar carbonaceous materials. It can also be used for calcining limestone, dolomite and cement rock, the decomposition of carbonates, chlorides and sulfates, and the activation or reactivation of charcoal.
It is therefore seen that the foregoing sets forth a system and process for receiving material in an area interm2diate and spaced from both the center and edge of a circular floor, and then, urging the material dm/
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: .. :, :
01~3 to both the center and edge of the circular floor in response to relative rotary motion between the floor and an adjacent rabble system disposed above the floor. It has also been shown how such a process and system is utilized to simul-taneously discharge material at both the center and outer periphery of such a floor. A rabble system has been detailed, which, by relative rotary motion, simultaneously urges material to both the center and peripheral edge of the floor.
Modified systems, capable of reGeiving two separate materials and moving them, without commingling, one to the center and the other to the outer periphery of the hearth, have been shown. Additionally, it has been shown how such a system and process is capable of handling normal quantities of materials at slow speeds without material pil~-up, large quantities of materials at relatively slow rotational speeds, and also how relatively large hearths can be utilized and -operated at relatively low rotational speeds.
While the foregoing preferred embodiments of:the invention have been described and shown, it is understood that alte~ation and modifications may be made thereto and fall within the scope of the invention as claimed.
dm~' -14-
Background of the Invention Field of the Invention The present invention relates to systems and methods especially suited for moving material during thermo-lytic processes in a rotary hearth. More specifically it relates to methods and apparatus for feeding, conveying and discharging coke during a calcining operation.
Prior Art Oven systems utilizing relative rotary motion be-tween a hearth and rabbles have long been used for heating and calcining material. Such systems normally include, for example, a heating chamber including a roof and cylindrical sidewalls, a circular hearth, a rabble system, a mechanism for imparting relative rotary motion between the rabbles and the hearth, suitable means for the admission of to-be-treated material into the oven, and other means for discharging treated material from the oven. Rabble systems have usually included a plurality of rabbles supported above and extending closely adjacent to the floor of the hearth for engaging and advancing the materials thereon from the area of entry to the point of discharge by relative rotary motion between the floor of the hearth and the rabbles.
The motion may be provided either by rotati~ the floor of the hearth while maintaining the rabbles stationary, or revolving the rabbles while maintaining the floor station-ary. Such systems may also include ports for the admission of oxidizing gases, and, if required, combustible gases, and an exhaust system for combustion by-products and spent gases. ~ -In such prior art rotary hearth systems, it is -believed that, the material to be treated has always been admitted either in the area at the center of the hear~th floor and transported by the rabbles to the peripheral dm/
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. . . : . ~
.. . . .
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edge of the hearth for discharge, or admitted in the area of the peripheral edge of the hearth floor and transported by the rabbles to the center of the hearth for discharge.
In such systems, the material to be treated is moved radially in only one direction during the treatment pro-vided, and, in most instances, only one material or mixture of materials can be treated in the system at any given time.
Such systems also have tended to be size and speed limited.
Small hearths have normally been capable of handling only limited amounts of material. Large hearths normally require more rabbles and a high rate of relative motion between the hearth and the rabbles. Where the rate of operation is relatively fast, it has been found to cause undesirable mechanical effects on the material under treatment, such as fracturing or generating of useless fine material. Fast operation also causes mechanical wear and - te~ ar on the equipment.
Calcining in rotary furnaces is taught, for;ex-ample, in U. K. Patent 1,055,857 and U. S. Patent 3,448,012.
U. S. Patents 319,180; 1,503,234; 3,612,497 and 3,~59,172 are typical of the many systems which teach movement of material from the center to the peripheral edge of a hearth. U. S. Patents 3,470,063; 3,475,286; 3,859,172 (noted above), and many others~ teach the flow of matçrial in a rotary hearth from the outer periphery to the center.
U. S. Patent 3,448,012 (noted above) also discloses a rotary hearth in which the material is moved from the periphery to the center in which the gas above the hearth is partitioned, without partitioning the material under-going treatment on the hearth.
U. S. Patent 740,103 is of interest as showing a rabbling system including two series of rabble blades" in which one series of blades may be at an angle to the other dm/ -2-. ~ , .
l(J~
series. However, it does not disclose a rotary hearth, it does not disclose feeding material intermediate the two series of rabbles, nor does it disclose the removal of material from the system at both the center and peripheral edge.
U.S. Patents 630,510 and 734,492 disclose rabble systems in which adjacent blades or rabble systems are inclined at an angle to one another to cause a backward and forward shifting of material on the hearth.
With the above in mind, it is the main object of the present invention to provide a system whereby material is received on a rotary floor at a point radially intermedi- -ate and spaced from the center and the peripheral edge of ~ -the floor, and in which a rabble system is provided which simultaneously urges the material from the area of deposit to both the center and peripheral edge of the floor in -~
response to relative rotary motion between the hearth floor and the rabble system.
Another object of the invention is to provide discharge points along both the center and the outer periphery of the floor to permit the simultaneous discharge of material from both points.
Another object of the in~ention is to provide a ~
rabble system whiCh, by relative rotary motion, is capable ~ -of simultaneously urging material to both the center and peripheral edge of the floor.
Another object of the invention is to provide a means whereby two separate materials are deposited at an inner and outer portion of the floor and moved, respect-ively, to the center and outer peripheral edge of thefloor without commingling.
Another object of the invention is to provide a large rotary hearth system which can operate at low speeds, dm/ -3-thus reducing the fracturing of material, the generation of fines and mechanical wear and tear on the equipment.
The foregoing objects and other objects defined herein are accomplished, generally, in a rotary hearth furnace having at least one point for the admission of to-be-treated material, which point is radially intermediate and spaced from both the center and the peripheral edge of the floor of the hearth. The area of the hearth radially inward from the area of material admission will be hereinafter referred to as the "inboard area" of the hearth. The ring shaped portion of the hearth outside of the point of material admission, and surrounding the inboard area will hereinafter be referred to as the "outboard area" of the hearth. Rabbles disposed above the floor of the hearth and capable of relative rotary movement with respect to the hearth are spaced radially outwardly from the center of the hearth. The rabbles are disposed " ~
.
dm/ _4_ - - lu~r)l~3 differently above the inboard area and outboard area of the hearth. The inboard rabbles are disposed to move material on the inboard area of the hearth inwardly toward the center of the hearth toward one or more centrally located discharge openings. The outboard rabbles are disposed to move the material on the outboard area of the hearth toward the outer periphery of the hearth toward one or more peripheral discharge openings. -If desired the floor or rabble system may carry a divider in the vicinity of the point of entry of the material to assist in defining inboard and outboard areas of the hearth.
In one modification, at least two material admission feeds are provided. These feeds can, if desired, be controlled so that different material is fed to the inboard area and to the outboard area of the hearth, thus allowing the simultaneous treatment of two different materials.
In one particular aspect the present invention provides an oven system comprising: a heated chamber including a roof and sidewalls; a substantially round hearth within said chamber, said hearth having a center and having a peripheral edge; a plurality of radially spaced rabbles within said chamber, said rabbles disposed above, but adjacent to, said hearth; means for providing relative rotary motion between said hearth and said rabbles; means for delivering material to said hearth, said delivery means being above said hearth and radially intermediate and spaced from both the center and the peripheral edge of said hearth; a material outlet at the center of said hearth; and a material outlet at the peripheral edge of said hearth; wherein said delivery means serve to define an inboard area and an outboard area on said hearth, the area of said hearth between the center of said -,. .
: - .
01~;~
hearth and a circumerence transcribed on said hearth by the radius between the centcr of sald hearth and thc delivery means being the inboard area, and the remalning ring area of said hearth radially beyond, the delivery means and sur-rounding the inboard area being the outboard area; and wherein said radially spaced rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said hearth progressively centerward towards the center material outlet and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said hearth progressively outward towards the peripheral material outlet in res.ponse to relative rotary motion between the hearth and the rabbles.
In another particular aspect the present invention provides in an oven of the rotary hearth type including: a heating chamber, said chamber defined by a roof, generally ~
cylindrical sidewalls and a generally circular hearth, said . ~ ~:
hearth having a center and a peripheral edge; a rabble system .
disposed above said hearth; means for providing relative rotary motion between said hearth and said rabble system; means for delivering to-be-treated material to said hearth, said delivery means being located above said hearth; means for removing material from said hearth and heating means to bring the oven to desired temperatures; wherein the improvement comprises, in combination: said material delivery means b.eing located radially intermediate and spaced from both said hearth center and peripheral edge; said material removing means includes at ~ -least one central outlet located at about the center of said :~
hearth and at least one peripheral outlet located at about the peripheral edge of said hearth; and wherein said rabble system includes at least an inboard and an outboard series of ~ -5a-,~
.,~, ~ , , ~, `` i~l301~3 rabbles, each series including a plurality of rabbles, said rabbles having an active face for engaging any material on said hearth during relative rotary motion between said hearth and rabble system, said inboard series of rabbles spaced progressively radially outward from about the central outlet of said hearth to about the radial distance of said material delivery means, substantially each rabble in said inboard series having its active face oriented at an angle to move any material on said hearth with which it makes contact during 10 relative rotary motion progressively inward toward said central outlet, said outboard series of rabbles spaced progressively radially outward from about the radial distance of said material delivery means to about the peripheral edge of said hearth, substantially each rabble in said outboard series having its active face oriented at an angle to move any :~
material on said hearth with which it makes contact during :-.
relative rotary motion progressively outward toward said peripheral outlet.
In yet another particular aspect the present invention 20 provides a material handling system including: a generally :.
circular substantially horizontal floor, said floor having a :~
, :, center and a peripheral edge; a plurality of radially spaced rabbles disposed above, but adjacent to said floor; means : .
for providing relative rotary motion between said floor and rabbles; and means for delivering material to said floor, said delivery means being above said.floor and radially ~
intermediate and spaced from both the center and the ~.
peripheral edge of said floor, said delivery means serving to define an inboard are.a and an outboard area on said floor, 30 the area of said floor, between the center of said floor and a circumference transcribed on said floor by the radius between said center of said floor and the delivery means jl/ ~ -5b-,. ....... .. . .... . . .. . . .......... .. .
~ ~ , . . .. :
:~.0~ 3 oeing the inboard area, and the remaining ring area of said floor radially beyond the delivery means and surrounding the inboard area, being the outboard area; and wherein said rabbles - above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said floor progressively towards the center of said floor and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said floor progressively outward towards the peripheral edge of said floor in response to relative rotary motion between the floor and the rabbles.
In a further particular aspect the present invention provides a process for handling material in a system including -~
a substantially round floor, said floor having a center and a peripheral edge, and a rabble system disposed above said floor, said process including the steps of: providing relative rotary motion between said floor and said rabble system; delivering material to be treated to said floor at an area intermediate both the center and the peripheral edge of said floor; and then in response to said rotary motion, simultaneously moving said material progressively from the area of delivery towards both the center and the peripheral edge of said floor.
Other details, objects and advantages of the invention will become apparent from the following detailed description.
Brief Description of the Drawings Fig. 1 is a diagrammatic top plan view of a rotary hearth according to the present invention.
Fig. 2 is an elevation through center section 2-2 of the rotary hearth according to Fig. 1.
Fig. 3 is a fragmentary sectional view of one modification of the invention.
~ ~ -5c-.
.
'JS~1~3 Fig. 4 is a still further modification of the inventive concept illustrated in tlle previous figures.
Description of the Preferred Fmbodiments The Oven System Reference is now made to the drawings, wherein ' ~' ~
-:
~ 5d-~O'iJ~t~3 like reference characters are employed to designate like parts throughout the several figures. Referring to FIGS. 1 and 2, an oven 10 having roof 12, sidewalls 14 and rotary hearth 16, define torroidal heating chamber 18. Hearth 16 is generally round and includes central opening 20 and peripheral edge 22. Feed bin 24 is located outside of the oven and is connected by means of tube 26 to chute 28 located within the oven. The bottom of chute 28 is located above the hearth to deliver material to the hearth for treatment.
Chute 28 is radially intermediate and spaced from both the central opening 20 and peripheral edge 22 of hearth 16.
Central opening 20 serves as a discharge outlet as does peripheral discharge outlet 32. These outlets are provided in the system to allow the removal of treated material from the hearth.
, For reference purposes, material delivery chute 28 defines an "inboard area" 34 and "outboard area" 36 of hearth 16 divided, for reference purposes in FIG. l by phantom circle 37. "Inboard area" 34 is the ring shaped surface of hearth 16 between central opening 20 and the circumference transcribed on the hearth by the radius ex-tending between the center of hearth 16 and chute 28.
"Outboard area" 36 is the ring shaped portion of hearth 16 which is radially beyond chute 28 and surrounding inboard area 34.
A radially extending depression in roof 12 pro-vides rabble pit 38 in which rabble support 40 is located.
~edge shaped rabble 42 carried by rabble support 40 is located at the same radial distance from the center of the hearth as chute 28. Rabble 42 serves to urge newly delivered material towards the inboard and outboard portion of the hearth, in response to rotation of the hearth in the counter clockwise direction indicated by dm/ -6-the arrow in FIG. 1. Other rabbles are also present in the system. As is art known, each rabble has an active face, not shown, which is oriented to contact and progessively -move material on the hearth in an inward or outward direction. Rabbles 44 carried by support 40 above inboard area 34 of hearth 16 are oriented at an acute angle to the radius of the hearth, thus placing their active faces in an orientation to move material on the hearth with which they come in contact progressively centerward. Inner most rabble 46 which also depends from rabble support 40 is located to plow material off of hearth 16 and into central discharge outlet 20, which leads, for example, to an art known heat boiler and cooler, not shown, In a similar manner, rabbles 48 carried by support 40 above outboard area 36 are oriented with their active faces at an oblique angle to the radius of the hearth to move material with which they come in contact during relative rotary motion progressively towards the periphery of the hearth. Outer most rabble 50 is located to plow material off of the hearth and into peripheral discharge outlet 32. Central discharge outlet 20 and peripheral discharge outlet 32 may feed to common or separate post treatment facilities, as desired.
In general, a space of about 0.5 to 4 inches (1.25 to 10 cm.l is maintained between the bottom of the rabbles and the bed of hearth 16. Rabble support 40 is adjustable, thus allowing an adjustment and variation of the vertical pen-etration of the rabbles into the bed of material under treatment. Additional detaIls of the system and its operation on to-be-treated material are set forth below.
Operation of the System Referring again to FIGS. 1 and 2, the operation of oven system 10 in the calcination of coke, for exa~ple, dm/
, . . .
O~S~3 is now described in detai~. Oven system 10 is pre-heated by art known means, not shown, to a temperature in the range of about 450C to about 1800C, and preferably from about 1000C to about 1550C. Counterclockwise rotation is initiated in hearth 16 by art known means, also not shown. Suitable heating, rotary drive apparatus and other hearth details are disclosed, for example, in U.S.
Patent 3,612,497. To-be-treated delayed petroleum coke having an average particle size of about n . 50 inch (1.28 cm.) and a maximum particle size of about 2 inches (5.8 cm.) is fed from bin 24 through tube 26 into feed chute 28. Feed chute 28 is adjusted so that its lower end is about 6 to 8 inches (15.2 to 20.1 cm.) above rotating hearth 16 to pro- -vide a circumferential band of coke on the hearth overlying - the interface 37 between inboard area 34 and outboard area 36 of the hearth. In the structure shown in FIGS. 1 and 2, wedge-shaped rabble 42 is immediately upstream of chute 28.
After one nearly complete revolution of hearth 16, coke deposited from chute 28 is moved into contact with wedge rabble 42 and caused to divide. A portion of the coke is urged onto inboard area 34 and a portion is urged onto out-board area 36 of hearth 16, the coke thus forming a pair of adjacent concentric windrows. The hearth continues to rotate in a counter-clockwise direction as indicated by the arrow -~
on FIG. 1. After one cornplete additional revolution, the coke urged onto inboard area 34 and outboard area 36 contacts and then begins to build-up against the leading or active faces of the inboard and outboard rabbles 44 and 48 which are next adjacent to wedge rabble 42. As coke piles up against the active faces of rabbles 44 and 48, a portion spills off at the back or trailing edge of each rabble, thus form-ing a pair of further separated windrows, not shown. These windrows are in turn carried around by the continued dm/ - -8-01~
rotation of hearth 16 until they come into contact with the next adjacent radially inward or outward rabbles 44 and 48.
This process is repeated progressively until the material reaches rabbles 46 and 50 at the center 20 and outer periphery 22 of the hearth. Then additional rotation of the hearth forces the material radially inward and outward of the last rabbles 46 and 50, respectively, and into discharge openings 20 and 32.
During the movement of the coke from chute 28 to discharge chutes 20 and 32, the coke is gradually heated.
Heating can be by means of air and combustible gases injected into the furnace by inlets, not shown, and ignited, or by the combustion of volatile combustible gas-es released from the coke as it is heated. In the latter - case, it is still required that air or other oxidizing gases be in~ected into the chamber to support combustion. In the calcining treatment of coke, heat from either form of -combustion in chamber 18 exceeds 2000F tlO93C). The heat in chamber 18 radiates directly onto the material under treatment and is also reflected from roof 12 and side-walls 14 of the oven thus aiding in the heating of the coké on the hearth.
The hearth rotates at a relatively slow rate, about 4 minutes for one complete revolution. Therefore, since repeated revolutions of the hearth are required to cause the coke to be shifted radially inward and outward ~
from rabble to rabble, the entire treating process may -require one hour or more.
Coke treated in this system by this process is calcined into a form of volatile free, dense carbon. It is useful, for example, for the production of electrodes ~ -used in the electrolytic production of aluminum, and in dm/ ~9~
10~ 3 other electrolytic operations.
Utilizing this system, for a given hearth rotating at a given speed, more material can be processed in a given time than is processed in prior art operations in which the to-be-treated material is unloaded at the center of the hearth and moved to the periphery, and vice-versa. This is due to the fact that the critical paramenter for treatment is temperature rather than time. Alternatively, this system per-mits the inboard and outboard half of the hearth to handle half of a normal material load with less material pile-up on rabbles and at a slower rate of revolution. In a similar manner, this system allows the usage of large hearths at relatively slow speeds to provide treatment of a greater amount of material ln a given period of time.
Alternative Embodiments A variety of modifications including those obvious to one skilled in the art are to be included within the scope of the invention as defined in the specification and the claims appended hereto. Referring to FIG. 3 one alterna-tive embodiment of the present invention is shown. In thisversion a pair of feed ohutes 28a and 28b are disposed respectively inboard and outboard of divider 52 carried on the floor of hearth 16. This arrangement allows the amount of material treated on the inboard and outboard sections of the hearth to be controlled. It also allows different materials to be treated on the inboard and outboard portions of the hearth without mixing or comingling them.
Z~e, ' '' I~ modification shown in FIG. 4, the hearth is tilted away from the area of material entry at interface dm/ ~10-'')',~ ' lt~
37a below chute 28 and towards the central and peripheral discharge chutes 20 and 32. In this embodiment, or in art known stepped or terraced versions, not shown, gravitational forces aid the r~bbles in movinq material across the hearth.
Other variations encompassing the present in-vention will be apparent to one skilled in the art. For example, more than one radial array of rabbles may be utilized to either increase stirring or maintain control of the material undergoing treatment on the hearth. The rabbles may be arrayed in other than a straight radial line.
For example, they may affect a spiral or a random pattern.
The only requirement is that each rabble be at the required ;~
angle and that the leading and trailing edge of each ad~
jacent rabble overlap or be sufficiently close to each other adjacent rabble to effectively move the material from the, area of deposit on the hearth to the central and peripheral discharge outlets. -While the spacing between the radially arranged !
rabbles may, if desired, be equal , these spacings may also vary to compensate for changes in the concentric areas of the hearth so as to maintain substantially constant depth of the bed of material across the hearth. For example, ~-~
in order to maintain a substantially constant depth of -material on the hearth, the rabbles disposed above the out~
bo~rd portion 36 of said hearth, progressing outward from j~
material delivery chute 28 to periphery 22 may progressively ; --decrease in spacing to compensate for an increase in the ring shaped area of the portion of the hearth overridden by each respective rabble as it is located farther from the center of the hearth. In a similar manner, the rabbles disposed inboard from said material delivery chute 28 to the center may progressively increase in radial spacing to compensate for a decrease in the ring shaped area of the dm/ -11-:.... , ' ' . - ~ . , - ' - . . . .; -' . -lV~ 3 hearth overridden by each respective inboard rabble as it is located closer to the center of the hearth.
The rabbles themselves may be constructed of high temperature materials, such as steel or mild steel coated with ceramic. They may be cooled by fluids circulating through the rabbles. One especially useful form of rabble is constructed of open grid metal filled with thermally-insuiating ceramic material, and includes a provision for circulating cooling fluids, as described in U.S. Patent 3,740,184.
Other than the fact that it must be spaced from both the edge 22 and center 20 of the hearth, the location of material inlet chute 28 is not critical. In some instances, it may be desirable to locate chute 28 at a point, such that inboard area 34 and outboard area 36 of the hearth are approximately equal. Such a location would be approximately determined by the formula:
r= 2 where; r, is the radial distance of the chute from the center of the hearth, and R, is the radius of the entire hearth.
This formula assumes that the area of central opening 20 is very small increment of the total area of the hearth.
Other factors may dominate the consideration of the location of supply chute 28. If the time of treatment of material on each half of the hearth is critical, then the number, spacing and size of rabbles acting on inboard hearth portion 34 and outbaord hearth portion 36 may be as important or more important than the area of the inboard and outboard portions.
Also, it is art known to utilize multiple supply dm/
. . ~ ' .- . :-lV~lZ3 chutes at either the center or periphery of the hearth, in conjunction with multiple rabble systems, to move a plurality of materials across the entire radius of the hearth, without commingling the materials, to preselected outlets, see U.S. Patent 3,859,172. Such systems may be improved, for example, by locating the multiple supply chutes in areas spaced from both the cçnter and peripheral edge of the hearth, along with multiple rabble systems, in accordance with the teaching of the present invention, to move a plurality of materials selectively to preselected outlets at the center or periphery of the hearth, in accordance with the teaching of the present invention.
In the example shown, the hearth rotates and the rabbles are stationary, and this is indeed the preferred embodiment. However, the present invention contemplates systems in which the hearth is stationary and the rabble system rotates around the center of the hearth.
While this method and apparatus has been shown to be useful, for example, for calcining coke for use in the production of electrodes, it is also useful for the continu-ous calcining, coking and/or devolatilizing of any carbonaceous material, such as non-coking coal,anthracite -coal, briquettes or pellets containing bituminous coking coal, green petroleum coke, wood products and other similar carbonaceous materials. It can also be used for calcining limestone, dolomite and cement rock, the decomposition of carbonates, chlorides and sulfates, and the activation or reactivation of charcoal.
It is therefore seen that the foregoing sets forth a system and process for receiving material in an area interm2diate and spaced from both the center and edge of a circular floor, and then, urging the material dm/
, .....
: .. :, :
01~3 to both the center and edge of the circular floor in response to relative rotary motion between the floor and an adjacent rabble system disposed above the floor. It has also been shown how such a process and system is utilized to simul-taneously discharge material at both the center and outer periphery of such a floor. A rabble system has been detailed, which, by relative rotary motion, simultaneously urges material to both the center and peripheral edge of the floor.
Modified systems, capable of reGeiving two separate materials and moving them, without commingling, one to the center and the other to the outer periphery of the hearth, have been shown. Additionally, it has been shown how such a system and process is capable of handling normal quantities of materials at slow speeds without material pil~-up, large quantities of materials at relatively slow rotational speeds, and also how relatively large hearths can be utilized and -operated at relatively low rotational speeds.
While the foregoing preferred embodiments of:the invention have been described and shown, it is understood that alte~ation and modifications may be made thereto and fall within the scope of the invention as claimed.
dm~' -14-
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED As FOLLOWS:
1. An oven system comprising: a heated chamber including a roof and sidewalls; a substantially round hearth within said chamber, said hearth having a center and having a peripheral edge; a plurality of radially spaced rabbles within said chamber, said rabbles disposed above, but adjacent to, said hearth; means for providing relative rotary motion between said hearth and said rabbles; means for delivering material to said hearth, said delivery means being above said hearth and radially intermediate and spaced from both the center and the peripheral edge of said hearth; a material outlet at the center of said hearth;
and a material outlet at the peripheral edge of said hearth;
wherein said delivery means serve to define an inboard area and an outboard area on said hearth, the area of said hearth between the center of said hearth and a circumference transcribed on said hearth by the radius between the center of said hearth and the delivery means being the inboard area, and the remaining ring area of said hearth radially beyond, the delivery means and surrounding the inboard area being the outboard area; and wherein said radially spaced rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the in-board area of said hearth progressively centerward towards the center material outlet and said rabbles above and ad-jacent said outbaord area are disposed at an angle of attack to move material on the outboard area of said hearth progressively outward towards the peripheral material outlet in response to relative rotary motion between the hearth and the rabbles.
and a material outlet at the peripheral edge of said hearth;
wherein said delivery means serve to define an inboard area and an outboard area on said hearth, the area of said hearth between the center of said hearth and a circumference transcribed on said hearth by the radius between the center of said hearth and the delivery means being the inboard area, and the remaining ring area of said hearth radially beyond, the delivery means and surrounding the inboard area being the outboard area; and wherein said radially spaced rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the in-board area of said hearth progressively centerward towards the center material outlet and said rabbles above and ad-jacent said outbaord area are disposed at an angle of attack to move material on the outboard area of said hearth progressively outward towards the peripheral material outlet in response to relative rotary motion between the hearth and the rabbles.
2. An oven as in claim 1 including means for injecting oxidizing gas into the heated chamber; and means for exhausting gases from said chamber.
3. An oven as in claim 1 wherein the hearth ro-tates and the rabbles are substantially stationary.
4. An oven as in claim 1 wherein said rabbles are arrayed generally radially from the center of said hearth to said outer periphery, said rabbles located inboard from the material delivery means being oriented in such a manner so that during relative rotary motion between said hearth and said rabble system the active face of substantially each inboard rabble proscribes an acute angle to the radius of the hearth while said rabbles located out-board from the material delivery means are oriented in such a manner that the active face of substantially each outboard rabble proscribes an obtuse angle to the radius of the hearth.
5. An oven as in claim 1 wherein means are pro-vided on said hearth to physically divide said inboard and said outboard areas.
6. An oven as in claim 1 wherein at least one complex rabble means is located at about the same radial distance from the center of the hearth as said material delivery means, said complex rabble means providing at least two active faces, one such face oriented to move any material on said hearth with which it makes contact during relative rotary motion toward said inboard area of said hearth, and a second active face oriented to move any material on said hearth with which it makes contact during relative rotary motion toward said outboard area of said hearth.
7. An oven as in claim 6 wherein said complex rabble means is in the form of a wedge.
8. An oven as in claim 1 wherein said hearth is downwardly inclined from below the area of material delivery means toward the material outlets at both the center and the peripheral edge of the hearth.
9. An oven as in claim 1 wherein said material delivery means is located at a distance r from the center of the hearth, wherein and wherein R is the radius of the entire hearth.
10. An oven as in claim 1 wherein said material delivery means includes at least two separate and distinct material delivery chutes, said chutes located radially intermediate and spaced from both said hearth center and peripheral edge.
11. An oven as in claim 10 wherein at least one delivery chute is disposed to deliver material preferentially to the inboard area of said hearth and at least one delivery chute is disposed to deliver material preferentially to the outboard area of said hearth.
12. An oven as in claim 11 wherein means are provided on said hearth to physically divide said inboard and said outboard areas.
13. In an oven of the rotary hearth type includ-ing: a heating chamber, said chamber defined by a roof, generally cylindrical sidewalls and a generally circular hearth, said hearth having a center and a peripheral edge;
a rabble system disposed above said hearth; means for provid-ing relative rotary motion between said hearth and said rabble system; means for delivering to-be-treated material to said hearth, said delivery means being located above said hearth; means for removing material from said hearth and heating means to bxing the oven to desired temperatures;
wherein the improvement comprises, in combination: said material delivery means being located radially intermediate and spaced from both said hearth center and peripheral edge;
said material removing means includes at least one central outlet located at about the center of said hearth and at least one peripheral outlet located at about the peripheral edge of said hearth; and wherein said rabble system includes at least an inboard and an outboard series of rabbles, each series including a plurality of rabbles, said rabbles having an active face for engaging any material on said hearth during relative rotary motion between said hearth and rabble system, said inboard series of rabbles spaced progressively radially outward from about the central outlet of said hearth to about the radial distance of said material delivery means, substantially each rabble in said inboard series having its active face oriented at an angle to said hearth with which it makes contact during relative rotary motion progressively inward toward said central outlet, said outboard series of rabbles spaced progressively radially outward from about the radial distance of said material delivery means to about the peripheral edge of said hearth, substantially each rabble in said outboard series having its active face oriented at an angle to move any material on said hearth with which it makes contact during relative rotary motion progressively outward toward said peripheral outlet.
a rabble system disposed above said hearth; means for provid-ing relative rotary motion between said hearth and said rabble system; means for delivering to-be-treated material to said hearth, said delivery means being located above said hearth; means for removing material from said hearth and heating means to bxing the oven to desired temperatures;
wherein the improvement comprises, in combination: said material delivery means being located radially intermediate and spaced from both said hearth center and peripheral edge;
said material removing means includes at least one central outlet located at about the center of said hearth and at least one peripheral outlet located at about the peripheral edge of said hearth; and wherein said rabble system includes at least an inboard and an outboard series of rabbles, each series including a plurality of rabbles, said rabbles having an active face for engaging any material on said hearth during relative rotary motion between said hearth and rabble system, said inboard series of rabbles spaced progressively radially outward from about the central outlet of said hearth to about the radial distance of said material delivery means, substantially each rabble in said inboard series having its active face oriented at an angle to said hearth with which it makes contact during relative rotary motion progressively inward toward said central outlet, said outboard series of rabbles spaced progressively radially outward from about the radial distance of said material delivery means to about the peripheral edge of said hearth, substantially each rabble in said outboard series having its active face oriented at an angle to move any material on said hearth with which it makes contact during relative rotary motion progressively outward toward said peripheral outlet.
14. A material handling system including: a gen-erally circular substantially horizontal floor, said floor having a center and a peripheral edge; a plurality of radial-ly spaced rabbles disposed above, but adjacent to said floor;
means for providing relative rotary motion between said floor and rabbles; and means for delivering material to said floor, said delivery means being above said floor and radially inter-mediate and spaced from both the center and the peripheral edge of said floor, said delivery means serving to define an inboard area and an outboard area on said floor, the area of said floor, between the center of said floor and a circumference transcribed on said floor by the radius between said center of said floor and the delivery means being the inboard area, and the remaining ring area of said floor radially beyond the delivery means and surrounding the inboard area, being the outboard area; and wherein said rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said floor progres-sively towards the center of said floor and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said floor progressively outward towards the peripheral edge of said floor in response to relative rotary motion between the floor and the rabbles.
means for providing relative rotary motion between said floor and rabbles; and means for delivering material to said floor, said delivery means being above said floor and radially inter-mediate and spaced from both the center and the peripheral edge of said floor, said delivery means serving to define an inboard area and an outboard area on said floor, the area of said floor, between the center of said floor and a circumference transcribed on said floor by the radius between said center of said floor and the delivery means being the inboard area, and the remaining ring area of said floor radially beyond the delivery means and surrounding the inboard area, being the outboard area; and wherein said rabbles above and adjacent said inboard area are disposed at an angle of attack to move material on the inboard area of said floor progres-sively towards the center of said floor and said rabbles above and adjacent said outboard area are disposed at an angle of attack to move material on the outboard area of said floor progressively outward towards the peripheral edge of said floor in response to relative rotary motion between the floor and the rabbles.
15. A process for handling material in a system including a substantially round floor, said floor having a center and a peripheral edge, and a rabble system disposed above said floor, said process including the steps of:
providing relative rotary motion between said floor and said rabble system; delivering material to be treated to said floor at an area intermediate both the center and the peripheral edge of said floor; and then in response to said rotary motion, simultaneously moving said material progressively from the area of delivery towards both the center and the peripheral edge of said floor.
providing relative rotary motion between said floor and said rabble system; delivering material to be treated to said floor at an area intermediate both the center and the peripheral edge of said floor; and then in response to said rotary motion, simultaneously moving said material progressively from the area of delivery towards both the center and the peripheral edge of said floor.
16. The process of claim 15 wherein material is delivered to a plurality of areas intermediate both the center and the peripheral edge of said floor.
17. The process of claim 16 wherein at least two different materials are delivered to at least two areas of said floor, one such material being moved progressively from its area of delivery towards the center of said floor and the second such material being moved progressively from its area of delivery towards the peripheral edge of said floor.
18. The process of claim 15 wherein said material handling system is included within a heating chamber, said materials under treatment contain volatile combustibles, said materials are heated, to drive off said volatile combustibles into said heating chamber, injecting oxidizing gas into said chamber and into admixture with said com-bustibles, and igniting said gaseous mixture to provide heat within said chamber.
19. The process of claim 18 wherein the material undergoing treatment is coke, and wherein the temperature in said chamber is raised to at least 1832°F (1000°C).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73407776A | 1976-10-20 | 1976-10-20 | |
| US734,077 | 1976-10-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090123A true CA1090123A (en) | 1980-11-25 |
Family
ID=24950217
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA288,983A Expired CA1090123A (en) | 1976-10-20 | 1977-10-19 | Split flow material handling system |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5351201A (en) |
| BR (1) | BR7707005A (en) |
| CA (1) | CA1090123A (en) |
| DD (1) | DD133707A1 (en) |
| DE (1) | DE2736537A1 (en) |
| EG (1) | EG12768A (en) |
| ES (1) | ES463377A1 (en) |
| FR (1) | FR2368678A1 (en) |
| IT (1) | IT1143710B (en) |
| NL (1) | NL7711488A (en) |
| NO (1) | NO773583L (en) |
| PL (1) | PL201599A1 (en) |
| SU (1) | SU694100A3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5353577A (en) * | 1976-10-26 | 1978-05-16 | Seiremu Fuaanisu Co | Method and apparatus for treating matter on rotary filter bed by heat |
| LU90766B1 (en) * | 2001-04-25 | 2002-10-28 | Wurth Paul Sa | Method of operating a multiple hearth furnace |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE739651C (en) * | 1936-08-01 | 1943-10-01 | Ing Alexej Lomsakov | Grate rotatable around a vertical axis |
| US3594286A (en) * | 1970-03-31 | 1971-07-20 | Wise Coal & Coke Co | Carbonizing multiple layers of material by maintaining reducing atmosphere in bed and oxidizing atmosphere above bed |
| SU438296A1 (en) * | 1971-06-10 | 1977-12-05 | Днепродзержинский Индустриальный Институт Им.М.И.Арсеничева | Annular roasting machine |
| US3998703A (en) * | 1975-02-06 | 1976-12-21 | Salem Corporation | Method of treating materials on a rotary hearth |
-
1977
- 1977-08-11 DE DE19772736537 patent/DE2736537A1/en active Pending
- 1977-08-22 EG EG492/77A patent/EG12768A/en active
- 1977-10-18 DD DD7700201580A patent/DD133707A1/en unknown
- 1977-10-19 BR BR7707005A patent/BR7707005A/en unknown
- 1977-10-19 ES ES463377A patent/ES463377A1/en not_active Expired
- 1977-10-19 PL PL20159977A patent/PL201599A1/en unknown
- 1977-10-19 NO NO773583A patent/NO773583L/en unknown
- 1977-10-19 CA CA288,983A patent/CA1090123A/en not_active Expired
- 1977-10-19 FR FR7731494A patent/FR2368678A1/en not_active Withdrawn
- 1977-10-19 SU SU772541199A patent/SU694100A3/en active
- 1977-10-19 IT IT28787/77A patent/IT1143710B/en active
- 1977-10-19 JP JP12466877A patent/JPS5351201A/en active Pending
- 1977-10-19 NL NL7711488A patent/NL7711488A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NL7711488A (en) | 1978-04-24 |
| JPS5351201A (en) | 1978-05-10 |
| SU694100A3 (en) | 1979-10-25 |
| BR7707005A (en) | 1978-08-22 |
| FR2368678A1 (en) | 1978-05-19 |
| IT1143710B (en) | 1986-10-22 |
| DE2736537A1 (en) | 1978-04-27 |
| PL201599A1 (en) | 1978-04-24 |
| DD133707A1 (en) | 1979-01-17 |
| ES463377A1 (en) | 1978-11-16 |
| NO773583L (en) | 1978-04-21 |
| EG12768A (en) | 1979-06-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |