CN209910399U

CN209910399U - Distributing device and rotary hearth furnace

Info

Publication number: CN209910399U
Application number: CN201920696613.1U
Authority: CN
Inventors: 倪明德
Original assignee: Shanghai Kelinwo Environmental Technology Co Ltd
Current assignee: Shanghai Kelinwo Environmental Technology Co Ltd
Priority date: 2019-05-15
Filing date: 2019-05-15
Publication date: 2020-01-07
Anticipated expiration: 2029-05-15

Abstract

The application relates to a distributing device and a rotary hearth furnace, and belongs to the technical field of metallurgy. The distributing device is used for distributing materials in a preset direction and comprises a discharger, wherein the discharger comprises a shell, the shell defines a cavity, and the shell is provided with a feeding hole and a discharging hole; the dividing piece is divided into at least three discharging bins, and the volume of each discharging bin is gradually reduced along the preset direction; the rotating shaft can drive the dividing pieces to rotate, and each discharging bin is provided with a feeding position and a discharging position which are switched along with the rotation of the dividing pieces; every discharge bin can be unloaded through feed inlet feeding and discharge gate in proper order at rotatory in-process. The volume of each discharging bin is gradually reduced along the preset direction, so that uneven distribution in the preset direction is achieved. The rotary hearth furnace comprises a furnace body, a furnace bottom and the material distribution device, wherein the furnace body is provided with an inner ring outer wall and an outer ring inner wall, and the material distribution device is respectively connected with the inner ring outer wall and the outer ring inner wall and is constructed for distributing materials at the furnace bottom between the inner ring outer wall and the outer ring inner wall.

Description

Distributing device and rotary hearth furnace

Technical Field

The application relates to the technical field of metallurgy, in particular to a distributing device and a rotary hearth furnace.

Background

The rotary hearth furnace is a coal-based direct reduction device, materials are conveyed to the rotary hearth in the furnace by utilizing the rotation of the furnace bottom machinery, furnace burden is preheated, reduced and cooled, the rotary hearth furnace adopts burner combustion gas and material reduction heat supply, and carbon-containing iron ore agglomerates (iron-containing dust/waste residue/iron ore and the like) are directly reduced to obtain solid direct reduction products.

The rotary furnace bottom of the rotary hearth furnace is circular, and the material reduction of the rotary hearth furnace is not uniform due to the equivalent feeding of a common material distribution device.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a distributing device and a rotary hearth furnace, and solves the problem that the distributing device of the rotary hearth furnace is uneven in distributing.

This application first aspect provides a distributing device for at preset orientation cloth, it includes the tripper, and the tripper includes:

the shell defines a cavity and is provided with a feed inlet and a discharge outlet which are communicated with the cavity and are oppositely arranged;

the dividing piece is rotatably arranged in the cavity through a rotating shaft and is divided into at least three discharging bins, and the volume of each discharging bin of the at least three discharging bins is gradually reduced along the preset direction;

each of the at least three discharge bins has a feed position and a discharge position that are switched as the divider rotates;

at least three discharging material silo can unload through feed inlet feeding and discharge gate in proper order at rotatory in-process, and discharging material silo is towards the feed inlet when the feed position, and discharging material silo is towards the discharge gate when the discharge position.

In the technical scheme, the material distribution device is used for distributing materials in a preset direction, and the material distribution device comprises a discharger which is used for discharging materials in the preset direction to achieve the purpose of distributing the materials;

the discharger comprises a shell, a rotating shaft and a dividing piece, wherein the dividing piece is arranged in the shell and divides the inner space of the dividing piece into at least three discharging bins, and the dividing piece can rotate through the rotating shaft;

the shell is provided with a feeding hole and a discharging hole, the discharging bins are provided with a feeding position and a discharging position, when the dividing piece rotates, each discharging bin firstly reaches the feeding position, namely the discharging bin faces the feeding hole, the material enters the discharging bins, each discharging bin rotates to reach the discharging position, namely the discharging bin faces the discharging hole, and the material is discharged to achieve the purpose of distributing;

the volume of each discharging bin is gradually reduced along the preset direction, so that when the discharging bins are used for feeding, materials contained in the discharging bins are gradually reduced along the preset direction, and when the discharging bins are used for discharging, the materials discharged from the discharging bins are gradually reduced along the preset direction, so that uneven distribution in the preset direction is achieved;

the stove bottom of rotary hearth furnace is the ring shape, and the radius of inner ring and outer loop differs great, and when the stove bottom was rotatory with same rotational speed, there was great difference at the linear velocity of inner ring and outer loop, adopts this application at the inhomogeneous cloth of presetting orientation (outer ring to the endocyclic vertical direction promptly) to make the material of outer ring cloth more, and the material of inner ring cloth still less to reach the even cloth of whole stove bottom.

In some embodiments of the foregoing first aspect, the axis of rotation extends through the discharger.

In this embodiment, the rotation axis runs through in the tripper, drives to cut apart the piece and rotates and realize continuous unloading and feeding.

In some embodiments of the foregoing first aspect, the divider comprises at least three divider blades connected to the rotary shaft, and the discharge bin is defined by two adjacent divider blades.

In this embodiment, the partition piece includes at least three partition leaves, and at least three partition leaves have the at least three discharge material silo of cutting apart into, and the quantity of partition leaf corresponds with the quantity of discharge material silo, and the partition leaf is connected in the rotation axis, and the discharge material silo is injectd by two adjacent partition leaves to reserve the import and export that is used for the feeding and the ejection of compact, thereby realize feeding in proper order and the function of ejection of compact in rotatory process.

In some embodiments of the aforementioned first aspect, the cavity has a truncated cone shape or a truncated pyramid shape, and an axial direction of the cavity coincides with the predetermined direction.

In this embodiment, the cavity is round platform shape or prismoid shape, and the height of every discharge bin reduces along the axial of cavity gradually, and the volume reduces along the axial of cavity gradually, reaches the effect of the inhomogeneous cloth of axial of every discharge bin along the cavity.

In some embodiments of the foregoing first aspect, the material distribution device comprises a feeder for guiding the material into the feed opening of the discharger, the feeder comprising:

the receiving mechanism is used for receiving materials;

the upper end of the blanking mechanism is communicated with the receiving mechanism, and the lower end of the blanking mechanism is communicated with the feed inlet of the discharger.

In this embodiment, the feeder is arranged in the guide material gets into the tripper, and during the material got into the feeder from the feed inlet that receives the material mechanism, the material arrived unloading mechanism from receiving the material mechanism in proper order, and misce bene in unloading mechanism to lead the material to advancing the tripper by unloading mechanism.

In some embodiments of the aforementioned first aspect, there is a storage bin between the feeder and the discharger that is capable of temporarily storing the material.

In this embodiment, the discharge bin can be used for storing a certain amount of material, prevents that the material from directly reaching the tripper by the feeder to jam or be difficult to control the cloth speed.

In some embodiments of the aforementioned first aspect, a weighing mechanism is provided between the feeder and the discharger for weighing into the discharger.

In this embodiment, the weighing mechanism is used to weigh the material entering from the feeder so that the feeding rate is detected by the output signal of the output module of the weighing mechanism.

In some embodiments of the aforementioned first aspect, a tripper is disposed between the feeder and the discharger, the tripper comprising a tripper frame.

In this embodiment, the material loosening device is used for the dispersed material, prevents that the material from blockking up in the distributing device, and the blocking leads to the cloth uneven and cloth inefficiency.

In some embodiments of the foregoing first aspect, the material distribution device includes a feeding mechanism for conveying the material to a feed opening of the material distribution device, and the feeding mechanism includes a belt feeder.

In this embodiment, the material is carried to the feed inlet of distributing device through belt feeder, ensures the continuation of material and stable feeding volume and speed.

The second aspect of the present application provides a rotary hearth furnace, which includes a furnace body, a furnace bottom, and the above-mentioned distribution device, wherein the furnace body has an inner ring outer wall and an outer ring inner wall, and the distribution device is connected with the inner ring outer wall and the outer ring inner wall respectively and is configured to distribute material at the furnace bottom between the inner ring outer wall and the outer ring inner wall.

In the technical scheme, the material distribution device is respectively connected with the outer wall of the inner ring and the inner wall of the outer ring to achieve the purpose of distributing material from the bottom of the material distribution device, so that the sealing performance of the rotary hearth furnace is ensured, and the leakage of smoke is prevented; the material distributing device can distribute more materials on the outer ring and less materials on the inner ring along the non-uniform material distribution in the vertical direction from the outer ring to the inner ring of the rotary hearth furnace, so that the uniform material distribution on the whole hearth is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic structural diagram of a material distribution device provided in an embodiment of the present application;

FIG. 2 is a top view of a tripper provided in accordance with an embodiment of the present disclosure;

FIG. 3 is a side view of a tripper provided in an embodiment of the present application;

FIG. 4 is a side cross-sectional view of a tripper provided in an embodiment of the present application;

fig. 5 is a schematic structural view of a cavity and a separation blade provided in the present embodiment;

FIG. 6 is a side view of a tripper according to further embodiments of the present application;

FIG. 7 is a side cross-sectional view of a tripper according to other embodiments of the present application;

FIG. 8 is a schematic view of a dispensing device according to further embodiments of the present disclosure;

FIG. 9 is a schematic structural view of a rotary hearth furnace according to further embodiments of the present application.

Icon: 10-a material distribution device; 110-a discharger; 111-a housing; 112-a partition; 113-a rotation axis; 114-a cavity; 115-feed port; 116-a discharge port; 117-discharge bin; 118-a separator leaf; 120-a feeding mechanism; 130-a motor; 140-a feeder; 141-a receiving mechanism; 142-a blanking mechanism; 150-a storage bin; 160-a weighing mechanism; 170-loosening device; 171-a pine rack; 20-furnace body; 210-inner ring outer wall; 220-outer ring inner wall; 230-furnace bottom.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The terms "upper", "lower", "inner", "outer", and the like, refer to an orientation or positional relationship based on that shown in the drawings, or that is conventionally placed during use of the product of this application, and are used only for convenience in describing and simplifying the application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.

In the description of the present application, it is also to be noted that the terms "disposed," "connected," and the like are to be construed broadly unless otherwise explicitly stated or limited. For example, the connection can be fixed, detachable or integrated; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Referring to fig. 1 and 2, a material distributing device 10 for distributing material in a predetermined direction according to an embodiment of the present invention includes a discharger 110 and a feeding mechanism 120, wherein the feeding mechanism 120 is used for conveying the material to the discharger 110.

The material distribution device 10 is used for distributing material in a predetermined direction, that is, the material distribution position of the material distribution device 10 is not limited to one point, but is distributed within a certain range.

The feeding mechanism 120 is a belt feeder, which can continuously convey the material to the discharger 110, and the speed and the conveying amount are very stable.

The material distributing device 10 does not necessarily need the feeding mechanism 120, and a manual feeding method may be used, and the feeding method is not fixed.

The discharger 110 includes a housing 111, a dividing member 112, and a rotating shaft 113.

The housing 111 defines a cavity 114, and the housing 111 has a feed inlet 115 and a discharge outlet 116 that communicate the cavity 114 and set up relatively, in this embodiment, the feed inlet 115 sets up in the upper end of the tripper 110, and the discharge outlet 116 sets up in the lower extreme of the tripper 110, thereby the material falls into the feed inlet 115 earlier because of the action of gravity and gets into the tripper 110, again because the action of gravity unloads the cloth from the discharge outlet 116, but the position of feed inlet 115 and discharge outlet 116 is not fixed, need set up according to the actual demand of unloading.

Cut apart piece 112 and set up in cavity 114, and cut apart and have at least three discharge bin 117, cut apart piece 112 and can rotate along predetermineeing the direction, and reach the feeding in rotating, store the function of material and ejection of compact, every discharge bin 117 has the feeding position and the ejection of compact position that rotate and switch along with cut apart piece 112, every discharge bin 117 can both be unloaded through feed inlet 115 and discharge gate 116 in proper order at rotatory in-process, when discharge bin 117 is in feeding position, discharge bin 117 feeds towards feed inlet 115, when discharge bin 117 is in ejection of compact position, discharge bin 117 unloads towards discharge gate 116, after discharge bin 117 passes through the feeding position, when still not reaching ejection of compact position, discharge bin 117 is in relative sealed state by shell 111 parcel.

It should be noted that the number of the discharging bins 117 is not fixed, and the three discharging bins 117 can ensure that any discharging bin 117 is not communicated with the feeding port 115 and the discharging port 116 at the same time, so as to avoid the material from directly reaching the discharging port 116 from the feeding port 115 for discharging, that is, the discharging amount and the discharging rate are extremely unstable. In this application embodiment, the discharge bin 117 is three, and in this application other embodiments, the quantity of discharge bin 117 can be four, five or even more, and the continuity of unloading can be guaranteed to the discharge bin 117 that the quantity is more, but when the quantity of discharge bin 117 exceeded eight, set up more and have not more obvious effect to the change of the continuity of unloading.

The volume of every discharge bin 117 reduces along predetermineeing the direction gradually, results in discharge bin 117 when the feeding, and the material of splendid attire reduces along predetermineeing the direction gradually in discharge bin 117, and discharge bin 117 when the ejection of compact, the material of unloading from discharge bin 117 reduces along predetermineeing the direction gradually to reach the inhomogeneous cloth in predetermineeing the direction.

Rotation axis 113 is connected with cutting apart piece 112 and is driven and cut apart piece 112 and rotate along predetermineeing the direction, and rotation axis 113 can be cut apart 112 outside and cut apart piece 112 and be connected the drive, also can run through in whole tripper 110, and rotation axis 113's the direction that sets up is unanimous with predetermineeing the direction, and in this application embodiment, rotation axis 113 runs through in whole tripper 110.

The rotation axis 113 can be driven by motor 130 and rotate, also can wave rotation axis 113 by the manpower, and motor 130 rotates more with stable, and the speed is more even, and the manpower waves unrestricted, and is more convenient. The power source of the rotating shaft 113 is not limited in this application, and in this embodiment, the motor 130 is used to drive the rotating shaft 113 to rotate.

Alternatively, referring to fig. 3, 4 and 5, the dividing member 112 includes at least three dividing leaves 118, the at least three dividing leaves 118 have at least three discharge bins 117 divided, and the number of the dividing leaves 118 corresponds to the number of the discharge bins 117. In the present embodiment, the dividing member 112 includes three dividing blades 118, the three dividing blades 118 have three discharge bins 117 divided, the three dividing blades 118 are connected to the rotary shaft 113, and each discharge bin 117 is defined by two adjacent dividing blades 118.

It should be noted that the present application does not limit the volume of each discharging bin 117, and each discharging bin 117 may have different or the same volume, which is determined according to the actual discharging requirement, but the present application embodiment requires a continuous and stable discharging rate, so in the present application embodiment, the volume of each discharging bin 117 is the same, and the discharging areas and the discharging rates are the same when the rotating shafts 113 rotate at the same speed.

When the rotating shaft 113 rotates, the three discharging bins 117 can sequentially reach the feeding position for feeding and the discharging position for discharging, so that the discharging continuity and stability of the distributing device 10 are realized.

Alternatively, when the cavity 114 may be a truncated cone or a truncated pyramid, the rotating shaft 113 passes through an axis of the truncated cone or the truncated pyramid, a lower bottom surface (a bottom surface with a larger area) of the truncated cone or the truncated pyramid is disposed at a beginning of the preset direction, and an upper bottom surface (a bottom surface with a smaller area) of the truncated cone or the truncated pyramid is disposed at an end of the preset direction, so that the volume of the whole cavity 114 is gradually reduced along the preset direction. Referring to fig. 5, the chamber 114 of the present embodiment is a circular truncated cone, the three dividing blades 118 divide the entire chamber 114 into three discharge bins 117, and the discharge bins 117 rotate around the rotating shaft 113 to sequentially discharge through the inlet 115 and the outlet 116.

When the material distribution speed needs to be adjusted, the material distribution speed can be changed by adjusting the material feeding speed of the material feeding mechanism 120, and the material feeding speed and the material discharging speed can be adjusted by changing the rotation speed of the cutting member 112 by changing the rotation speed of the rotating shaft 113, so that the material distribution speed can be changed.

Referring to fig. 6 and 7, in the distributing device 10 provided in the embodiment of the present application, the discharger 110 includes eight separating blades 118, the separating blades 118 divide the cavity 114 into eight discharge bins 117, the eight discharge bins 117 sequentially reach the feeding position, i.e., the discharge bin 117 faces the feeding port 115, and the discharging position, i.e., the discharge bin 117 faces the discharging port 116, so as to achieve seamless and stable discharging, and almost every feeding time is discharging, so as to achieve equal exchange of feeding and discharging.

Referring to fig. 8, the present embodiment provides a material distributing device 10, which includes the above-mentioned discharger 110 and feeding mechanism 120, and further includes a feeder 140, a storage bin 150, a weighing mechanism 160, and a material loosening device 170. The feeder 140 is in communication with the discharge bin 117, the weighing mechanism 160 is disposed within the storage bin 150, and the tripper 170 is disposed between the discharge bin 117 and the tripper 110.

The feeder 140 includes a receiving mechanism 141 and a discharging mechanism 142, in this embodiment, the receiving mechanism 141 is a receiving hopper, the receiving hopper is funnel-shaped, the feeding mechanism 120 is a belt feeder, the belt feeder directly conveys the material to the upper end of the receiving hopper, and the material falls into the receiving hopper under the action of gravity;

the upper end of unloading mechanism 142 and the lower extreme intercommunication that receives material mechanism 141, the material that receives in the material mechanism 141 gets into unloading mechanism 142 by the action of gravity, and in this application embodiment, unloading mechanism 142 is two spiral blanking machines, and two spiral blanking machines can further mix the material and transport the material to the lower extreme of unloading mechanism 142, and the material falls into storage silo 150 by the action of gravity.

Storage silo 150 is used for the storage material, and storage silo 150 can provide stable material that lasts for discharger 110, guarantees the stable speed that discharger 110 unloaded, and simultaneously, when the splendid attire had the material of take the altitude in discharge silo 117, can guarantee that the flue gas can not follow the lower extreme of discharger 110 and upwards stretch and lead to revealing, has guaranteed the leakproofness of discharger 110 lower extreme.

The weighing mechanism 160 is disposed in the storage bin 150, the weighing mechanism 160 is used for weighing the weight of the material entering the storage bin 150 from the feeder 140, the weighing mechanism 160 is connected with a signal output module, and the feeding rate can be determined according to the output signal of the weighing mechanism 160, so as to determine whether the feeding and feeding rates of the feeding mechanism 120 and the discharging mechanism 142 need to be adjusted.

The material loosening device 170 is arranged between the discharging bin 117 and the discharger 110, and the material loosening device 170 is used for dispersing materials and preventing the materials from being blocked in the material distribution device 10 to form blocks, so that the material distribution is uneven and the material distribution efficiency is low. In this embodiment, the material loosening device 170 includes the material loosening frame 171, and the material loosening frame 171 is vibratile ground frame structure, has arranged a plurality of holes that are used for the pine material in the frame structure, and when the material entered into material loosening device 170 from discharge bin 117, the material caused the vibration of material loosening frame 171 by gravity action contact material loosening frame 171, made the material roll further fall into the feed inlet 115 of tripper 110 in the hole of material loosening frame 171, realized the purpose of pine material, prevented that the material from containing more moisture, the agglomeration.

Referring to fig. 9, an embodiment of the present application further provides a rotary hearth furnace, which includes a furnace body 20 and a material distribution device 10, wherein the furnace body 20 is annular, the furnace body 20 has an inner annular outer wall 210 and an outer annular inner wall 220, the inner annular outer wall 210 and the outer annular inner wall 220 together define an annular furnace bottom 230, and the furnace bottom 230 is used for containing materials and preheating, reducing and cooling the materials.

The material distribution device 10 is connected to the inner ring outer wall 210 and the outer ring inner wall 220, respectively, and configured to distribute material on the furnace bottom 230 between the inner ring outer wall 210 and the outer ring inner wall 220. In the embodiment of the present application, the material distribution device 10 is fixedly connected to the inner ring outer wall 210 and the outer ring inner wall 220 of the furnace body 20 through the connecting hole on the side wall thereof, so as to ensure the sealing performance of the rotary hearth furnace and prevent the flue gas from leaking from the gap between the material distribution device 10 and the furnace body 20.

The preset direction of the distributing device 10 is the direction of the furnace bottom 230 from the outer ring to the inner ring, wherein the length of the preset direction is the same as or approximately the same as the vertical distance from the outer ring to the inner ring of the furnace bottom 230, that is, one end of the discharger 110 along the preset direction is aligned with the inner ring, and the other end is aligned with the outer ring.

The distance between the distributing device 10 and the furnace bottom 230 is 80-100 mm, so that the discharger 110 can be ensured to realize uniform distribution of the whole furnace bottom 230.

In the using process, the material distribution device 10 is arranged in the furnace body 20 with the preset direction thereof as the direction from the outer ring to the inner ring, the furnace bottom 230 is in rotation, the discharger 110 discharges materials at the rotating speed of 4-7 r/min relative to the static furnace wall, and the actual rotating speed is determined according to the thickness of a material layer required to be controlled by the process.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A distribution device for distributing a material in a predetermined direction, the distribution device comprising a discharger, the discharger comprising:

the shell defines a cavity and is provided with a feeding hole and a discharging hole which are communicated with the cavity and are oppositely arranged;

the at least three discharging bins can sequentially discharge through the feeding port and the discharging port in the rotating process, the discharging bins face the feeding port in the feeding position, and the discharging bins face the discharging port in the discharging position.

2. The dispensing apparatus of claim 1 wherein said rotatable shaft extends through said discharger.

3. The distribution device according to claim 2, characterized in that said dividing member comprises at least three dividing leaves connected to said rotary shaft, said discharge bin being defined by two adjacent dividing leaves.

4. The distributing device according to claim 1, wherein the cavity is truncated cone-shaped or truncated pyramid-shaped, and an axial direction of the cavity is in accordance with the predetermined direction.

5. The material distribution device of claim 1, wherein the material distribution device comprises a feeder for guiding the material into the feed opening of the discharger, the feeder comprising:

the receiving mechanism is used for receiving materials;

the upper end of the blanking mechanism is communicated with the receiving mechanism, and the lower end of the blanking mechanism is communicated with the feeding hole of the discharger.

6. The distribution device according to claim 5, characterized in that between the feeder and the discharger there is a storage silo which can temporarily store the material.

7. Material distribution device according to claim 5, characterized in that a weighing mechanism is arranged between the feeder and the discharger for weighing into the discharger.

8. The material distribution device of claim 5, wherein a tripper is disposed between the feeder and the discharger, the tripper comprising a tripper frame.

9. The material distribution device according to claim 1, wherein the material distribution device comprises a feeding mechanism, the feeding mechanism is used for conveying materials to a feeding hole of the material distribution device, and the feeding mechanism comprises a belt feeder.

10. A rotary hearth furnace comprising a furnace body having an inner ring outer wall and an outer ring inner wall, a hearth, and a distribution device according to any one of claims 1 to 9, the distribution device being connected to the inner ring outer wall and the outer ring inner wall, respectively, and being configured to distribute material at the hearth between the inner ring outer wall and the outer ring inner wall.