CARBON BAKING FURNACE WITH SYSTEM FOR CONTROLLING MOVEMENT OF SACRIFICIAL MEDIUM AND ANODES THROUGH THE BAKING PATH

Abstract

A carbon baking furnace has at least one vertical baking shaft with a system and method for positioning green carbon bodies to be baked at the tops of the vertical baking paths and ringing the green carbon bodies with a sacrificial medium such as packing coke. The disclosure provides a carbon baking furnace having a system and method for unloading baked carbon bodies at the bottom of an array of baking paths while supporting the column of carbon bodies remaining in the baking path. The disclosure provides a volatile extraction system that extracts volatile fumes from the upper portion of the furnace and introduces the volatile fumes to the burners in the baking portion of the furnace. This system allows the volatile fumes to be selectively directed to an afterburner and automatically delivered to the afterburner during an emergency.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 61/714,634 filed Oct. 16, 2012; the disclosures of which are incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The present disclosure generally relates to carbon baking furnaces and, more particularly, to carbon baking furnaces having vertically-disposed baking paths. In one configuration, the invention relates to a furnace having at least one vertically-disposed baking path used to bake a carbon body that travels down through the baking path while packed in a sacrificial medium.

2. Background Information

Various operations require green carbon to be baked prior to use. Some of these operations use granulated green carbon while others use blocks of green carbon. One such baking operation is the manufacture of anodes that are later used to make aluminum. The conversion of alumina to aluminum metal by electrolysis results in the substantial consumption of carbon anodes. Molten aluminum is deposited onto a carbon cathode and simultaneously oxygen is deposited on and consumes the carbon anode of the electrolytic cell. Typically, up to 0.4 tonnes of carbon are consumed for every tonne of aluminum produced. As a result, aluminum smelters have a requirement for a substantial and continuous supply of carbon electrodes. Smelters commonly manufacture carbon anodes on site as an integral part of the aluminum production process.

The manufacture of carbon anodes for the aluminum manufacturing process includes producing “green” anode blocks and baking the “green” blocks to produce anodes suitable for use in the aluminum manufacturing process. The production of “green” blocks involves the mixing of crushed coke or anthracite with a binding agent which, for example, contains coal tar pitch. The viscous mixture is then pressed to form “green” anode blocks. Depending on the smelter's requirements, “green” anodes may typically weigh from a few hundred kilograms to more than a tonne. The mixture of coke and pitch binder is generally solid at room temperature and softens at temperatures over about 50 degrees C. Volatile components are released at temperatures between 50 degrees C. and 400 degrees C. When subjected to further heating over a period of time, to about 1200 degrees C., the anode hardens, resulting in improved physical properties, such as electrical conductivity and resistance to oxidation.

A carbon anode baking furnace having a substantially vertical baking path is disclosed in U.S. Pat. No. 7,086,856 which is incorporated herein by reference. Green anodes are packed in sacrificial media within the vertical baking path and moved down through a baking zone. The baked anodes are removed from the bottom of the baking path along with a portion of the sacrificial medium that surrounds the anodes. The movement of the sacrificial medium within the baking path must be controlled such that the removal of the bottom anode does not upset the packing of the sacrificial medium about an anode disposed higher up the baking path.

Another issue with the vertical-path furnace such as that disclosed in U.S. Pat. No. 7,086,856 is the removal of the baked anodes at the bottom of the furnace. The anodes are disposed in a self-supporting column while in the baking path. The problem of removing the lowermost baked anode while not upsetting the column is an issue desirous of improvement.

SUMMARY OF THE DISCLOSURE

The disclosure provides a carbon baking furnace having at least one vertical baking shaft with a system and method for positioning green carbon bodies to be baked at the tops of the vertical baking paths and ringing the green carbon bodies with a sacrificial medium such as packing coke.

The disclosure provides a carbon baking furnace having at least one vertical baking shaft with a system and method for controlling the sacrificial medium used to surround the carbon bodies within the baking paths. The system and method includes elements disposed at the top of the furnace where the sacrificial medium is loaded and elements disposed at the bottom of the furnace where the sacrificial medium is unloaded.

The disclosure provides a carbon baking furnace having a system and method for unloading baked carbon bodies at the bottom of an array of baking paths while supporting the column of carbon bodies remaining in the baking path.

The disclosure provides a volatile extraction system that extracts volatile fumes from the upper portion of the furnace and introduces the volatile fumes to the burners in the baking portion of the furnace. This system allows the volatile fumes to be selectively directed to an afterburner and automatically delivered to the afterburner during an emergency.

The disclosure will now be further described with reference to the accompanying drawings. In the drawings the carbon articles are represented by anodes for use in the aluminum smelting industry. It will be understood that the features of the present invention applies equally to the baking of other carbon articles provided in block or granular form.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an exemplary configuration of a vertical-path carbon baking furnace having a plurality of baking paths arranged in an array.

FIG. 2 is a top view of the exemplary furnace configuration of FIG. 1.

FIG. 3 is a perspective view of the top of the furnace showing six anodes positioned at their uppermost position with three of the baking paths empty for purposes of showing the structures around the top of the baking path. FIG. 3 also shows the system for loading sacrificial medium into the baking paths around the anodes.

FIG. 4 is a perspective view of the top of a baking path with the anode removed to show the anode guides, the brushes, and the sacrificial medium conveyors. This view also shows openings in the refractory block that define the inlets to the volatile fume removal system.

FIG. 4A is a perspective view of a liner for a volatile fume extraction channel.

FIG. 5 is a view similar to FIG. 4 with the refractory block removed.

FIG. 6 is a perspective view from inside the baking path looking up to the top of the baking path with the refractory block removed for clarity.

FIG. 7 is a perspective view of the loading end of a conveyor used to deliver sacrificial medium to the top of the baking path around an anode.

FIG. 8 is a perspective view of the end of the conveyor of FIG. 7 showing the adjustment mechanism for the drive chain.

FIG. 9 is a perspective view of the conveyor of FIGS. 7 and 8 showing the brush and the delivery openings that allow the sacrificial medium to exit the conveyor into the baking path around the anode.

FIG. 10 is a top perspective view of a portion of the conveyor of FIGS. 7 and 8 showing an idler roller and a paddle that is used to distribute the sacrificial medium along the length of the conveyor.

FIG. 11 is a perspective view showing the afterburner and the stack with a schematic interconnection between the two.

FIG. 12 is a perspective view of the side of the furnace showing the equipment used to extract the volatile fumes and direct them into the main furnace burners.

FIG. 13 is a perspective view of the side of the furnace showing the main furnace burners and the pipes used to deliver the volatile fumes.

FIG. 14 is an end view of a coke removal structure at the bottom of the baking path that controls the removal of the sacrificial medium.

FIG. 14A is a cross section of the coke removal structure showing the movement of the sacrificial medium with schematic arrows.

FIG. 15 is a perspective view of the end of the structure shown in FIG. 14.

FIG. 16 is a perspective view looking up into the bottom of the bottom of an anode baking path showing the location of the structure of FIG. 15 and also showing the actuation mechanism.

FIG. 17 is a perspective view of the system used to unload the baked anodes from the furnace.

FIG. 18 is a perspective view looking up into the bottom end of the baking path showing the holding devices used to support the anode column while the lowermost anode is removed from the furnace.

FIG. 19 is perspective view of an end wall of the furnace showing the end support for the mechanism of FIGS. 14 and 15.

FIG. 20 is a perspective view looking down through the bottom of a baking path with the refractory block removed for clarity.

FIG. 21 is a perspective view of a mechanism that unloads the lowermost baked anode and controls the movement of the anodes through the baking path.

FIG. 22 is a perspective view of the mechanism of FIG. 21 with portions removed to show additional features.

FIG. 23 is a side perspective view showing the holding devices of FIG. 18 engaged with the anode while the lowermost anode is removed.

FIG. 24 depicts the drive assembly for the grippers that hold the anode stack during the unloading of an anode.

FIG. 25 depicts a pair of grippers disposed on a common drive shaft.

FIG. 26 is a perspective view of six volatile extraction channels shown without the refractory brick.

Similar numbers refer to similar parts throughout the specification.

DETAILED DESCRIPTION OF THE DISCLOSURE

An exemplary configuration of the vertical-path baking furnace is identified by reference numeral 10 in the following description. FIG. 1 depicts a front view of furnace 10 while FIG. 2 depicts a top view of furnace 10 showing the location of a plurality of carbon body baking paths 12 arranged in a three-by-four array with three baking path rows and four baking path columns. The array of baking paths 12 thus includes a plurality (in this example ten) of perimeter baking paths that are not entirely surrounded by other baking paths and, in this example, a plurality (two) of captured baking paths 12 that are entirely surrounded (when viewed from the top) by other baking paths 12. The array of baking paths includes a front row 14 of baking paths 12, a middle row 16, and a back row 18. In other array configurations, there will be a different number of middle rows 16. The front row is the closest to the unloading direction at the bottom of furnace 10. In FIG. 2, the baked carbon bodies are unloaded from the bottom of the baking paths 12 in the direction that faces the bottom of the drawing page which corresponds to the direction toward the viewer in FIG. 1 (this is the front 20 of furnace 10).

Green carbon bodies 30 are loaded into baking paths 12 at the top of furnace 10 and unloaded at the bottom of furnace 10 where the baked carbon bodies 30 are unloaded from a bottom of a baking path 12. The unloading process controls the downward movement of the carbon bodies 30 through furnace 10 during the baking process such that each vertical column 32 of carbon bodies 30 is supported from the bottom. Carbon bodies 30 move through furnace 10 in a substantially continuous manner and the time for a single carbon body 30 to move through baking path 12 is many hours. It will be understood that the term “substantially continuously” refers to a continuous mode of operation whereby carbon bodies 30 are moved in either a uniform rate or a periodic or step-wise passage through furnace 10. Carbon bodies 30 are moved “substantially continuously” through the baking process without the need for furnace 10 to be shut down and cooled as in prior art in-ground anode baking furnaces. The substantially continuous movement includes the periodic stopping of the downward movement of column 32 that is required to unload the lowermost carbon body 30 from baking path 12.

The following exemplary configuration of furnace 10 is described as an anode baking furnace. Other carbon articles may be baked in this type of furnace and the inventions described herein are not to be limited to anodes used for aluminum production. Furnace 10 may be used with other block-like carbon articles or loose granular carbon articles.

The exemplary carbon baking furnace 10 shown in FIGS. 1 and 2 defines a plurality (twelve in this example) vertical baking paths 12. Paths 12 are defined by a plurality of interlocking refractory blocks and other refractory materials 40 that are partially supported by an external support frame 42 that is disposed below and around refractory block 40. Refractory block 40 defines baking paths 12, a plurality of fume channels for hot baking gas flow, and a plurality of volatile fume channels (inlets 44 seen in FIG. 4) for removing volatiles from furnace 10 upon the initial heating of green anodes 30. These volatile fume channels may be lined with a removable liner 45 shown in FIG. 4A. Liner 45 defines a plurality of inlet slits 47 that are aligned with inlets 44 when liner 45 is installed. Liner 45 also includes an end flange that abuts the exterior of the blocks to position liner as shown in FIG. 12 Frame 42 includes a plurality of lower supports 46 that support refractory block 40 above the floor 48 on which furnace 10 is supported. Lower supports 46 provide space for the unloading of the baked anodes 30.

As the carbon anodes 30 pass through furnace 10, they are loaded at a loading zone at the top of furnace 10 and then pass down through a volatile extraction zone. Volatiles such as pitch fumes are extracted through holes or inlets 44 in the refractory materials 40 and are moved in the manner described below. Anodes 30 then pass through a baking or kiln area where the anodes baked at high temperatures and then to the unloading zone.

Green anodes 30 are positioned at the top of baking paths 12 with a delivery device 50 which may be in the form of the crane 50 depicted in the drawings. Crane 50 supports anode 30 from its center (at depressions defined by the top of the anode) so that each anode 30 may be lowered into baking path 12 without requiring supports disposed at the sides or under article 30. If desired, this configuration allows crane 50 to load anode 30 all the way to the bottom of baking path 12 when furnace 10 is initially loaded. Anodes 30 also may be loaded from the bottom of each column. Further, this configuration allows crane 50 to reach into baking path 12 to remove anode 30 as needed. A spacer 52 may be positioned on top of each anode 30. Spacer 52 may be fabricated from a refractory material such as a ceramic. Spacer 52 may be provided in multiple sections that fit together on top of anode 30. The sections may overlap and have stepped edges of stepped joints to help spacer 52 fit together.

After a column is initially loaded and furnace 10 is fired and has reached steady state, the anode column is slowly lowered in a substantially continuous manner to bake the anodes. As the column is lowered, a new green anode 30 is placed at the top of the column. The initial placement of anode 30 is such that anode 30 is disposed intermediate guides 60 of which at least one is disposed on each side of the top of baking path 12 such that anode 30 is centered above path 12. The initial location places the majority of the height of anode 30 above the top of baking path 12. As column 32 of anodes 30 is lowered through path 12, sacrificial medium such as granular packing coke is positioned around anode 30 by a sacrificial medium delivery system 64.

In the exemplary configuration of furnace 10, anodes 30 are loaded into the tops of the baking paths 12 with overhead crane 50 that lowers anode 30 directly into the baking path 12. Crane 50 is capable of lowering anode 30 all the way to the bottom of each baking path 12 which is one method of initially loading furnace 10. Furnace 10 is initially loaded by creating columns 32 of anodes 30 surrounded by the packing material. The anode columns also may be created working from the bottom of furnace by pushing successive greens anodes 30 up into the baking columns. FIG. 2 depicts ten of the columns loaded (three with spacers 52 on top of the anode column 32) and two empty baking paths 12 waiting to be filled. After columns 32 of anodes 30 are established in each baking path 12, furnace 10 is started and brought up to its steady state operating condition and the anode columns 32 are lowered as described below. When a column 32 is lowered to a level where the column 32 can accept the next anode 30, the crane 50 is directed to pick up the next anode 30 and deliver it directly on top of that column 32. Once anode 30 is in position and crane 50 releases anode 30, the recesses in anode 30 used by crane 50 are filled with packing material and then spacer 52 is placed on top of anode 30. Spacers 52 may be supported by a second swinging crane (not shown) during the process of positioning them for placement.

Furnace 10 may include sensors that indicate the position of the top of the anode columns. The position of the anode column also may be monitored by the removal of the lower baked anodes. Crane 50 may communicate with these sensors to trigger the pick up and delivery of the next anode to be loaded.

The next anode 30 is positioned directly on top of the anode column 32 by a plurality of upper guides 60 shown in FIGS. 4 and 5. Upper guides 60 are passive. Each upper guide 60 is mounted on a guide base 70 and includes an arm 72 that is cantilevered from guide base 70. A curved guide foot 74 is carried by the distal end of arm 72 in a position such that the straight bottom of guide foot 74 is substantially vertical and disposed tangential to a portion of the anode column 32. The top of guide foot 74 is curved or angled back toward guide base 70 (away from its anode column 32) so that an anode 30 being lowered through guides 60 will be guided into the correct position by the upper curved portion of guide foot 74 in the situation where anode 30 is not perfectly aligned with anode column 32 by crane 50 or when the dimensions of anode 30 are slightly out of spec. A pair of conical springs 76 are positioned against each other and between guide foot 74 and arm 72 to allow the position of guide foot 74 to automatically adjust. In the exemplary configuration, guide foot 74 is connected to arm 72 with a pair of bolts 78 and conical springs 76 are carried on bolts 78 disposed between arm 72 and guide foot 74.

A flexible seal 80 defined by a plurality of overlapping brushes 82 having metal bristles is positioned at the upper end of each baking path 12. The overlapping portions of brushes 82 at their corners may be notched as shown in FIG. 6. Seal 80 engages the perimeter of anode 30 as anode 30 drops down through seal 80. Seal 80 is disposed over the top of the sacrificial medium and limits migration of air into the sacrificial medium.

Each section of seal 80 includes a plurality of metal bristles mounted in a U-channel 84 that is clamped between an L-shaped base mount 86 and a mounting strip 88 positioned over U-channel 84. This configuration is depicted in FIGS. 9 and 10.

Furnace 10 includes an overall sacrificial medium delivery system that generally includes at least one sacrificial medium storage container and at least one sacrificial medium conveyor that delivers sacrificial medium from the container to the space around the top of anode column 32. In the exemplary configuration of furnace 10, one sacrificial medium conveyer assembly 64 is disposed on each side of each row of anodes 30 such that there are six sacrificial medium conveyors 64 in this exemplary configuration. Each of the six sacrificial medium conveyors 64 is fed by its own sacrificial medium hopper 90. Each sacrificial medium hopper 90 is filled automatically by a supplier conveyor (not shown) or manually by the person overseeing the operation of furnace 10.

Each sacrificial medium conveyor 64 includes an elongated channel 92 and a sacrificial medium dispersement apparatus. Channel 92 is loaded with sacrificial medium from hopper 90 at its upstream end where the dispersement apparatus moves sacrificial medium downstream through channel 92. The loading may be a gravity feed. Apparatus 94 includes a motor 96 that drives a belt 98 having paddles 100 disposed within channel 92. Paddles 100 push the sacrificial medium in the downstream direction past a plurality of outlets 102 defined by the inner wall of channel 92 disposed adjacent anode column 32. Outlets 102 are disposed under seal 80.

Hoppers 90 are held in place with a plurality of spaced U-bolts as shown in FIG. 7. The outlet of hopper 90 is disposed below belt 98. This configuration allows each hopper 90 to be readily removed if necessary. Belt 98 is supported on a drive gear 104 (FIG. 7), and end idler gear 106 (FIG. 8), and at least one intermediate idler gear 108 (FIG. 10). Additional intermediate idler gears 108 may be provided as needed to avoid belt sag. End idler gear 106 is supported on tension bracket 110 movable by turning tension bolt 112. Paddles 100 are L-shaped sections of metal bolted to belt 98.

Outlets 102 are elongated and spaced apart. A plurality of outlets 102 have a length that is roughly four or more times as long as the height of outlet 102. The height is large enough to accommodate the largest size of sacrificial medium and the large width minimizes clogged outlets 102 while also allowing for uniform distribution of sacrificial medium along anodes 30. As shown in FIG. 6, an outlet 102 is disposed at the corner of anode 30 so that sacrificial medium is distributed to the ends of anodes 30 where the sacrificial medium fills in the ends by way of gravity at the angle of repose for the sacrificial medium. Openings 102 at corners may be larger than the other openings to promote the distribution of sacrificial medium in these locations.

Nitrogen gas may be introduced into channels 92 such that the nitrogen will migrate down into sacrificial medium around anodes 30. Flooding the sacrificial medium with nitrogen limits the amount of oxygen surrounding anode column 32 and thus limits any combustion within the sacrificial medium. A fire suppression system also may be integrated into or just below channels 92 to flood the areas around the anode column with a fire suppressant.

The sacrificial medium moves down through baking path 12 with anodes 30 and accommodates the movement and size changes of anodes 30 during the baking process. The sacrificial medium may move at a rate that is different from anodes 30. A lower seal 120 shown in FIGS. 14, 15 and 20 supports the sacrificial medium and also limits migration of air into the bottom of the sacrificial medium. Lower seal 120 is similar to upper seal 80 in that it includes overlapped brushes 82 with metal bristles. In the exemplary configuration, a plurality of stacked brushes 82 are used to form seal 120. The ends of the brush bristles are clamped in a U-channel 84 that is received directly in a slot defined by an inner wall 122 of a sacrificial medium removal channel 124. In the same manner as with channels 92, there is one removal channel 124 disposed along each side of each row of baking paths 12. In the exemplary configuration, there are thus six removal channels 124.

The sacrificial medium is stopped by lower seal 120 and is moved over inner wall 122 into channel 124 between inner wall 122, an outer wall 126, and a bottom wall 128 which define the upper portion of channel 124. Bottom wall 128 of channel 124 defines openings which allow the sacrificial medium to drop down into an elongated inlet 130 to a sacrificial medium control mechanism 132 which functions as an intermediate channel portion of removal channel 124. Mechanism 132 controls the movement of sacrificial medium by removing the sacrificial medium only as needed by automatically removing the sacrificial medium from the top of a control channel 134. The top of control channel 134 is positioned above the bottom of elongated inlet 130 such that sacrificial medium must move upwardly before dropping onto an angled wall 135 of a lower gathering channel portion of removal channel 124. The gathered sacrificial medium is then removed to by way of a chute assembly 136 into a collection hopper or is removed by chute assembly 136 to a conveyor that delivers sacrificial medium back to hoppers 90.

Control channel 134 catches the sacrificial medium and prevents it from simply falling out of furnace 10 by changing the flow direction of the sacrificial medium. In order to control the movement, control channel 134 rocks back and forth on a pivot 138 about which its end panels 140 are mounted. The rocking movement pushes the top portions of the sacrificial medium resting in control channel 134 over its edges into the gathering channel portion below. The material is pushed by the lower portions of elongated inlet 130 as channel 134 rocks back and forth as indicated by reference arrow 142 in FIG. 14A. The other arrows in FIG. 14A depict the movement of the sacrificial medium. Control channel 134 is driven back and forth by a drive mechanism 144 (schematically shown in FIG. 16) which is connected to each of removal channels 124 by linking rods 146. Drive mechanism 144 rod 146 back and forth to rock each of control channels 134. In the exemplary configuration, drive mechanism 144 is a cylinder that drives rod 146A back and forth below the metal beams that support refractory block 40. A slot 148 may be defined in lower support 46 to accommodate rod 146A (see FIG. 16). Drive rod extensions 146B are connected to drive rod 146A and to channel 134 (or to tabs that extend down from channel 134 as shown in FIG. 26). Drive rod extensions 1468 transfer to movement of drive rod 146A to control channel 134. Channels 134 may be rocked with their own individual actuators.

Intermediate guides 160 are disposed above seal 120 to ensure anode column 32 is properly positioned for removal from furnace 10. Intermediate guides 160 have a similar structure as upper guides 60 and the same reference numerals are used to identify these elements of guides 160. The arms 72 of intermediate guides 160 extend down into sacrificial medium removal channel 124 and may abut bottom wall 128 of channel 124.

Chute assembly 136 moves the sacrificial medium out of furnace 10 to a location where it can be screened and recycled. Chute assembly 136 includes a plurality of lateral funnels 162 and a plurality of corner funnels 164.

Lower guides 180 are disposed below seal 120 and position anode 30 to be held by the holding mechanism 182 that supports anode column 32 in place while the lowermost anode 30 is removed from furnace 10. Lower guides 180 have a similar structure as upper guides 60 and the same reference numerals are used to identify these elements of guides 180.

The holding mechanism includes a plurality of curved, toothed holding grippers 190 mounted to a rotatable drive shaft 192 that is rotated by a drive assembly 194. Drive assembly 194 rotates shaft 192 and thus pivots grippers 190 between engaged and disengaged positioned. When the lowermost anode 30 is ready to be removed from column 32, drive assembly 194 is actuated to pivot grippers 190 into engagement with the side of anode 30 as shown in FIG. 23. As the lowermost anode 30 is moved down, the next highest anode 30 starts moving down under the weight of column 32 causing grippers 190 to bite into the side of that anode 30 until grippers 190 pinch that anode to a standstill. Column 32 thus stops moving and the lowermost anode is removed as described below.

An example of a drive assembly 194 is depicted in FIG. 24 wherein cylinders 196 drive lever arms 198 that, in turn, rotate drive shafts 192. This arrangement allows all of the grippers 190 to be controlled from the outer ends of furnace by extending shafts 192 out to the furnace ends and locating cylinders 196 in these locations.

The downward movement of anode column 32 is controlled by the movement of a screw jack 200 positioned directly under column 32. Screw jack 200 is configured to move slowly such as when it is being used to drop anode column 32 down along baking path 12 during the baking of anodes 30. Screw jack 200 can also move relatively fast such as when it is removing the lowermost anode 30 from furnace 10. Screw jack 200 maintains its slow movement until grippers 190 are holding column 32. Screw jack 20 then changes to its faster movement and lower the lowermost anode 30 down to a gravity powered passive conveyor 202 which removes the anode to a removal area 203 (FIG. 17) where a forklift can remove the baked anodes.

During this process, the anode 30 from the front row 14 of the baking path array is removed first and the screw jack 200 remains retracted down under the conveyor 202 until the anodes from the middle 16 row is removed and, following the same process, the anode from the back row 18 is removed. In an alternate configuration, the back row anode may be removed from the back of the furnace. This process allows the anodes from the middle and back rows to slide down conveyors 202 without being stopped by the jack screws for the front row of anodes. After anodes 30 are removed from all rows 14, 16, and 18, screw jacks 200 are extended back up to engage columns 32. In order to break the grip of grippers 190, screw jacks 200 lift column 32 up until grippers 190 release or are driven back to their disengaged positions. At that time, screw jack 200 starts moving column 32 downward again until the new lowermost anode 30 is ready for removal. This process may be reserved to initially load furnace 10. If loaded from the bottom, screw jack 200 lifts an anode 30 to grippers 190 where it is held until pushed up by the next anode 30 being loaded.

As shown in FIGS. 21 and 22, screw jack 200 extends through the center of conveyor 202. An engagement plate 204 is carried at the top of screw jack 200 to engage anode 30. Plate 204 is supported at five locations including the powered central screw 206 and four corner guides 208.

As described above, furnace 10 has a volatile extraction zone where anodes 30 are initially heated and volatiles are driven off into extraction channels 45 such as the one depicted in FIG. 4A. FIG. 26 shows the arrangement of six channels 45 and their communication with a volatile extraction main duct 210. Duct 210 delivers volatiles to the burners 211 as shown in FIG. 13 when a first gate valve 212 is open and a second valve 214 (at the top of duct 210) is closed. Gate valves 212 and 214 are controllable to deliver the volatile fume to either burner 211 or to an afterburner 216 (FIG. 11). Each gate valve 212 and 214 has its own actuator to allow the valve to be automatically controlled. When first gate valve 212 is closed and second gate valve 214 is open, volatile fume is delivered to afterburner and this configuration is automatically actuated during an emergency situation or when burners 211 are off. Afterburner 216 exhausts to stack 218 for delivery to the atmosphere or to further environmental controls.

Burners 211 and the air delivery ducts are mounted to accommodate expansion and contraction of the refractory blocks of furnace 10. FIG. 13 shows each burner 211 mounted to a plenum 220 that accommodates movement of the refractory block. A plurality of springs 222 are used between the components and frame 42 to create a holding force against the block while allowing for accommodation of block movement. The air delivery system uses similar springs and adjustable plenums to accommodate movement.

In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the furnace is an example and the furnace is not limited to the exact details shown or described. Throughout the description and claims of this specification the words “comprise” and “include” as well as variations of those words, such as “comprises,” “includes,” “comprising,” and “including” are not intended to exclude additives, components, integers, or steps.

Claims

1. A vertical path carbon baking furnace for baking green carbon articles; the furnace comprising:

a furnace body defining a substantially vertical baking path adapted to receive the carbon article; the vertical baking path having a volatile extraction zone disposed above a baking zone;

the furnace body defining a volatile extraction inlet in communication with the baking path; the volatile extraction inlet being disposed in the volatile extraction zone of the baking path;

the furnace body defining baking fume channels disposed on opposite sides of the baking path to receive baking fumes;

a burner associated with each the baking fume channel; and

the volatile extraction inlet in fluid communication with a burner such that volatile fumes extracted from the baking path through the volatile extraction inlet are delivered to the burner for combustion.

2. A vertical path carbon baking furnace for baking green carbon articles; the furnace comprising:

a furnace body defining a substantially vertical baking path adapted to receive the carbon article; the baking path having upper and lower ends;

a sacrificial medium delivery system disposed at the top of the baking path;

the sacrificial medium delivery system including a pair of channels disposed on opposite sides of the baking path; each of the channels defining outlets adapted to deliver sacrificial medium from the channel to the baking path; and

a sacrificial medium conveyor disposed in the channels; the conveyor having movable elements that deliver sacrificial medium to the channel outlets along the length of the channels.

3. A vertical path carbon baking furnace for baking green carbon articles; the furnace comprising:

a furnace body defining a substantially vertical baking path adapted to receive the carbon articles in a stacked column wherein the stacked column has a lowermost article and a second lowermost article; the baking path having upper and lower ends;

an unloading device disposed under the baking path to control the movement of the column through the baking path;

a holding mechanism associated with the baking path; the holding mechanism having elements that selectively support the second lowermost article independent of the lowermost article; and

the holding mechanism including a plurality of grabs that selectively rotate downwardly and inwardly relative to the article from a disengaged position to an engaged position; the plurality of grabs including grabs disposed on opposite sides of the article such that the weight of the article causes the article to be pinched and held by the opposed grabs.