US20110067999A1

US20110067999A1 - 400kA HIGH ENERGY EFFICIENCY REDUCTION POT

Info

Publication number: US20110067999A1
Application number: US12/994,728
Authority: US
Inventors: Dingxiong Lv; Youwei Wu; Xiquan Qi; Shaoxian Ma; Jihong Mao; Hui Dong; Dequan Wang; Jingxiong Liu; Yu Mao; Yongjun Guan
Original assignee: Northeastern University Engineering and Research Institute Co Ltd
Current assignee: Northeastern University Engineering and Research Institute Co Ltd
Priority date: 2008-05-27
Filing date: 2009-05-25
Publication date: 2011-03-24
Also published as: CA2725840C; WO2009143696A1; AU2009253630B8; CA2725840A1; RU2456381C1; AU2009253630A1; AU2009253630B2; CN101280435A; CN101457370B; CN101457370A

Abstract

A 400 kA high energy efficiency reduction pot, comprising: anode carbon blocks, anode busbars, crust breaking and feeding device, anode lifting device, girders and pillars, pot hooding and exhausting system, cathode busbar arrangement structure, cathode carbon blocks, cathode lining structure and cathode pot shell, the pot is characterized in that: 1) superstructure and portal-type pillars are supported by pipe truss girders structure; 2) anode carbon block has eight steel stubs to be configured in a symmetrical mode; 3) the superstructure has 24 double-anode assemblies or 48 single-anode assemblies, six alumina feeding points, and two fluoride salt feeding points; 4) sub-section fume collecting and exhausting system is installed between a horizontal hood plate and a feeding hopper; 5) a device for sealing the anode rod by means a negative pressure suction is provided; 6) a new lining structure of holding heat on bottom, dispersing heat from side, and adding expansion layer at the cathode end have been designed based on the simulation of the electric field and thermal field; 7) the cathode busbars adopt a non-symmetrical configuration, and six power incoming points on the long side of the pot is provided; and 8) rectangular pipe truss girders are used as both air-supply pipeline above the pot and a silencer for tailed air from the crust breaking and feeding cylinder. The present invention has markedly energy-saving and emission reduction effect.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a technical field of aluminum electrolysis, particularly, to a structure of prebaked anode aluminum reduction pot, which is a kernel apparatus employed in a molten bath method for producing aluminum. More particularly, the present invention relates to an ultra-large capacity 400 kA high energy efficiency reduction pot.
2. Description of the Related Art
It has been known that the conventional prebaked anode aluminum reduction pot is mainly consisting of two portions, i.e., a superstructure and a cathode structure. The superstructure comprises anode carbon blocks assemblies, anode busbars, crust breaking and feeding device, anode lifting mechanism, girders, portal-type pillars, and pot fume hooding system. The cathode structure comprises cathode carbon blocks, pot lining structure and pot shell structure. There are several problems in the conventional prebaked anode aluminum reduction pot. In order to overcome these problems, Chinese Patent No. CN200510047245.0 discloses a new design of the large capacity prebaked anode aluminum reduction pot. This invention is primarily directed to construction and operation of 160 KA˜360 KA prebaked anode aluminum reduction pot.
Nowadays, with capacity increasing of the prebaked anode aluminum reduction pot, it encounters new problems including magnetic fluid stability, cathode structure, superstructure of the reduction pot, and effective hooding of pot fume. Thus, the skilled in the art should take serious considerations on these matters.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a new solution which alleviates the conflicts due to the increased capacity of the pot, such as the increased difficulties of optimized arrangement of cathode busbar, the increased energy consumption and the increased discharge of pot fume, in a ultra-large capacity 400 kA high energy efficiency reduction pot. Hereby, the new-type 400 kA high energy efficiency reduction pot has been presented after carrying out the improvements on the above large capacity prebaked anode aluminum reduction pot.
A 400 kA high energy efficiency reduction pot, comprising: anode carbon blocks, anode busbars, crust breaking and feeding device, anode lifting device, girders and pillars, pot hooding and exhausting system, cathode busbar arrangement structure, cathode carbon blocks, cathode lining structure and cathode pot shell, the pot is characterized in that:
1) superstructure and portal-type pillars are supported by pipe truss girders structure;
2) anode carbon block has eight steel stubs to be configured in a symmetrical mode;
3) the superstructure has 24 double-anode assemblies or 48 single-anode assemblies, six alumina feeding points, and two fluoride salt feeding points;
4) sub-section fume collecting and exhausting system is installed between a horizontal hood plate and a feeding hopper;
5) a device for sealing the anode rod by means a negative pressure suction is provided;
6) a new lining structure of holding heat on bottom, dispersing heat from side, and adding expansion layer at the cathode end have been designed based on the simulation of the electric field and thermal field;
7) the cathode busbars adopt a non-symmetrical configuration, and six power incoming points on the long side of the pot is provided; and
8) rectangular pipe truss girders are used as both air-supply pipeline above the pot and a silencer for tailed air from the crust breaking and feeding cylinder.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the pipe truss girder structure comprises a connecting beam and crane support provided between two truss girders, characterized in that:
the truss girder has the connecting beam as the top thereof and is comprised of the portal-type pillars, upper chords, lower chords, straight web members, and diagonal web members, all of which take the form of rectangular steel pipes; wherein
1) the straight web members are distributed at a certain space between the upper chords and the lower chords;
2) the inclined chords are placed between the upper chords and the lower chords, at both sides of the straight web members;
3) the straight web members and the inclined chords provided at both sides of the straight web members are arranged to have a umbrella shape or inverted umbrella shape in turn; and
4) the connecting beam is positioned on the tops of the straight web members and is at the same vertical plane with the upper chords.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the anode carbon block assembly has eight symmetrical steel stubs comprising cross beams and stubs, characterized in that: the cross beam is comprised of two main cross beams, two diagonal cross beams, and four small cross beams, wherein:
1) main cross beams and diagonal cross beams are connected in a transverse X-shape;
2) the middle portion of each small cross beam is vertically connected to ends of the main cross beams;
3) both ends of each small cross beam are curved downwards to be connected to the stubs, and the bottom of the stubs is fixed on the carbon block; and
4) a central portion where the two diagonal cross beams are intercrossed with each other is upwardly connected to the anode rod.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said new anode arrangement scheme comprises aluminum reduction pot cavity, anode carbon blocks, and feeding points, characterized in that:
1) all the feeding points are disposed in the position where the four anode carbon block assemblies converge;
2) the gaps between carbon blocks of two adjacent anode assemblies at the feeding points is widened while the gaps between carbon blocks of two adjacent anode assemblies at the non-feeding points is narrowed; and
3) four corners of the anode carbon blocks at the feeding points are cut off to widen the space of the feeding points.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the sub-section fume collecting and exhausting system comprises pot fume flue, a main flue, and a control valve, characterized in that:
1) the flue is disposed inside an interlayer between the horizontal hood plate and the feeding hopper, the lower portion of the feeding hopper is fabricated into V-shaped configuration, instead of welding to the plate girder;
2) the flue is divided into two parallel branch fume pipes and disposed respectively inside the left and right interlayers between the horizontal hood plate and the feeding hopper of the aluminum reduction pot
3) the two branch fume pipes each further comprises front air inlet and rear air inlet;
4) the main flue to which the two branch fume pipes are led is provided with the control valve.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said device for sealing the anode rod by use of a negative pressure suction is provided, the device comprises lateral plate, front end plate, and top plate, characterized in that: the device is a cavity formed by the two lateral plates, top plate, and front end plate and configured to surround around three sides of the anode rod, wherein
1) a grating structure is adopted for the three surrounded sides of the anode rod at the front end of the cavity device;
2) rear end of the cavity is welded to the web beam and communicated to the horizontal flue; and
3) the cavity device is positioned over the horizontal hood plate which is used as a bottom plate.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said new lining structure is designed on basis of simulation of the electric field and thermal field, and the lining structure comprises cathode carbon blocks, cathode steel bar, and bottom refractory material layer, characterized in that:
1) the cathode steel bar is located in the pot shell, and a portion of the steel bar exposed out of the cathode carbon blocks is clamped by a U-shaped metal plate, and then tamped with the refractory castable;
2) the cathode steel bar is wrapped with the refractory insulating paper, and, is filled with steel bar paste;
3) the middle bottom of the cathode carbon is provided with granular refractory material while both ends thereof are provided with refractory bricks; and
4) a straight edge paste structure, instead of an arc edge paste structure, is provided between the cathode carbon blocks and the side wall silicon carbide bricks.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the cathode busbars adopt non-symmetrical configuration and power incoming from six-point on long side of the pot, the cathode busbars comprise a busbar on power incoming side; a busbar on outgoing side, a cathode flexible busbar on power incoming side, a cathode flexible busbar on outgoing side, a pot bottom busbar; and riser busbar, characterized in that:
1) the local compensation busbar is further provided, the local compensation busbar enters the bottom of the pot, and goes out along of the end of the aluminum reduction pot, then, is lifted to a certain height; and
2) 56 cathode flexible busbars and 6 riser busbars are used to supply power for the aluminum reduction pot, the number of the cathode flexible busbars to be connected to the 6 riser busbars is 10: 9: 9: 9: 9: 10, respectively.
The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the rectangular pipe truss girder is also used as both the air-supply pipeline and a silencer for tailed air from the crust breaking and feeding cylinder, comprises a compressed air pipeline, a crust breaking cylinder, a feeding cylinder, and aluminum tapping cylinder, characterized in that:
1) the compressed air pipeline is connected to the rectangular steel pipe of the truss in the X direction via an one-way air inlet valve;
2) the rectangular steel pipe of the truss in the X direction is connected to the air inlet pipes of the crust breaking cylinder, the feeding cylinder, and the aluminum tapping cylinder via an electromagnetic control valve; and
3) the tailed air exhausting pipes of the crust breaking cylinder, the feeding cylinder, and the aluminum tapping cylinder are connected to the rectangular steel pipes in the X direction or in the Y direction, via the electromagnetic control valve.
Compared with the present representative 300 kA family prebaked anode aluminum reduction pot, the 400 kA high energy efficiency reduction pot according to the present invention at least has following advantages:
1) The cathode busbars have more economic and safer arrangement, and there is a much more uniform distribution of the current. Due to the adoption of the non-symmetrical configuration of cathode busbar around the pot and six-point power incoming from the long side of the pot, the impacts of the adjacent aluminum reduction pots and the busbar currents of the adjacent potroom to the magnetic field distribution are compensated, the requirements for the stability of the magnetic fluid of the aluminum reduction pot are satisfied; the phase difference of the equal voltage drop among these branches are minimized, and, the phase difference of the equal voltage drop on the power incoming and outgoing sides of each branch are minimized, so that the security during baking period of the aluminum reduction pot is ensured; and, the consumption of busbars is the lowest under the condition that the busbar voltage drop is equal.
2) The lining structure design of the aluminum reduction pot is accorded with the principle of enhancing thermal insulation on the pot bottom and improving heat dissipation at the pot sides, to ensure different isothermal lines exist in the correspond lining refractory thermal layer, so as to improve the operation of the aluminum reduction pot and prolong its service life.
3) There is an optimized steel structure design for the aluminum reduction pot. Particularly, the aluminum reduction pot adopts a boat-type cradle with single rib structure and a pipe truss girder superstructure. Thus, the steel consumption and the processing difficulty are greatly reduced.
4) There is a more optimized arrangement of the feeding point position. Particularly, the new anode carbon blocks arrangement, including six alumina feeding points and two fluoride salt feeding points, is adopted, such that, the gaps among the carbon blocks are narrowed, while the feeding space is widened suitably, and the effective work area of the anode are added. Therefore, not only the energy consumption is reduced, but also the production is increased.
5) There is an optimized fume collecting system for the aluminum reduction pot. Particularly, this system eliminates the air leaking due to the installation of the crust breaking and feeding device, by effectively using negative pressure caused by the temperature difference in the pot hood. Therefore, the uniformity of the negative pressure distribution in the hood and the fume collecting efficiency from the flue of the aluminum reduction pot are greatly improved, and, the thermal energy utilization rate of the aluminum reduction pot is also increased to some extents.
In all, compared with the conventional 300 kA family pre-baked anode aluminum reduction pot, the 400 kA high energy efficiency reduction pot according to the present invention has markedly energy-saving and emission reduction effect, and also, it has great economic benefits and well spreading value.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other structures and advantages of the 400 kA high energy efficiency reduction pot of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a general structure front view of a pre-baked anode aluminum reduction pot according to the present invention;

FIG. 2 is a general structure side view of the aluminum reduction pot according to the present invention;

FIG. 3 is a structural schematic view of a pipe truss girder according to the present invention;

FIG. 4 is a structural schematic view of 8 steel stubs of anode according to the to present invention, FIG. 4A is a stereogram view of the steel stubs, and, FIG. 4B is schematic view showing the steel stubs are in a assembled state;

FIG. 5 is a schematic view of an anode arrangement of the aluminum reduction pot according to the present invention;

FIG. 6 is a structural schematic view of a sub-section fume collecting and exhausting system, FIG. 6A is a front view of the system, and, FIG. 6B is a plan view of the arrangement of a flue;

FIG. 7 is a structural schematic view of a sealing device for anode rod according to the present invention, FIG. 7A is a plan projection view of the sealing device, and, FIG. 7B is a sectional view along line B-B of the FIG. 7;

FIG. 8 is a horizontal structure schematic view of a lining of the aluminum reduction pot according to the present invention;

FIG. 9 is a structure schematic view of a cathode busbar arrangement of the aluminum reduction pot according to the present invention, FIG. 9A is a elevation of the cathode busbar arrangement, and, FIG. 9B is a plan schematic view of the cathode busbar arrangement; and

FIG. 10 is a schematic view of the pipe truss gird provided at the superstructure of the aluminum reduction pot, which is used as an air supply pipeline and a silencer for tailed air from the crust breaking and feeding cylinder.

In the figures, the following reference numeral designates the following component:

- 1. bottom beam; 2. boat-type cradle pot shell with single rib; 3. lining; 4. pillar; 5. anode busbar; 6. anode clamp; 7. anode lifting mechanism; 8. crust breaking and feeding device; 9. anode carbon block; 10. cathode carbon block; 11. pot cover plate; 12. main flue; 13. portal-type pillars; 14. lower chord; 15. upper chords; 16. diagonal web member; 17. straight web member; 18. crane supporter; 19. connecting beam; 20. main cross beam; 21. small cross beam; 22. cant beam; 23. stub; 24. anode rod; 25. aluminum reduction pot cavity; 26. feeding point; 27. gap between anodes at feeding point; 28. gap between anodes at non-feeding point; 29. centre gap; 30. feeding hopper; 31. U-shaped flue steel plate; 32. flue branch pipe; 33. horizontal hood plate; 34. anode balance busbar; 35. flue manifold; 36. control valve; 37. lateral plate; 38. front end plate; 39. top plate; 40. granular material; 41. thermal baffle; 42. high temperature resistance thermal baffle; 43. heat insulation brick; 44. bath corrosion resistance brick; 45. heat insulation felt; 46. U-shaped metal plate; 47. refractory castable; 48. silicon carbide brick; 49. arc side paste; 50. refractory insulating paper; 51. cathode steel bar; 52. steel bar paste; 53. power incoming side busbar; 54. end bypass busbar; 55. pot bottom busbar; 56. local compensation busbar; 57. power outgoing side busbar; 58. riser busbar; 59. flexible busbar on the power incoming side; 60. flexible busbar on the power outgoing side; 61. short-circuit busbar; 62. crust breaking cylinder; 63. feeding cylinder; 64. blast pipe for crust breaking cylinder; 65. return air pipe of crust breaking cylinder; 66. blast pipe of feeding cylinder; 67. return air pipe of the feeding cylinder; 68. backblowing air pipe; 69. compressed air pipe; 70. one-way control valve; 71. cylinder tailed air exhausting pipe; 72. manual control valve.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

These and/or other structures and advantages of the 400 kA high energy efficiency reduction pot according to the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings.
According to the present invention, the superstructure of the 400 kA high energy efficiency reduction pot includes anode carbon block assembly 9, anode busbars 5, crust breaking and feeding device 8, an anode lifting device 7, and pillar 4, a subsection fume collecting and exhausting system consisting of pot cover plate 11, main flue 12 and flue branch pipe 32. The cathode structure comprises cathode carbon blocks 10, a lining structure, and a pot shell structure.
With reference to FIGS. 1 and 2, the 400 kA high energy efficiency reduction pot is taken as an example for purpose of detailed description of the present invention. As a matter of fact, the present invention can also be applicable to the ultra-large capacity 400 kA˜550-kA family high energy efficiency reduction pot.
1. The Superstructure of The Aluminum Reduction Pot
1) Girder and Pillar
As shown in FIG. 3, the upper chords 15 and the lower chords 14 employ rectangular steel pipes of 200 mm (the length)×200 mm (the width)×10 mm (the thickness); and, the straight web members 17 and the diagonal web members 16 employ rectangular steel pipes of 150 mm (the length)×150 mm (the width)×8 mm (the thickness). The straight web members 17 are disposed at a certain space between the upper chords 15 and the lower chords 14, and they are joined together by welding, respectively. That is to say, the straight web members and the inclined chords provided at both sides of the straight web members are arranged in turn. After the assembly of the two truss girders, connecting beams 19 are mounted at the upper chords 15 of the two truss girders, at the top of the straight web members 17 along a direction perpendicular to the truss girders. Further, the connecting beams 19 are respectively connected to the upper chords 16 of the truss girders by welding. Then, portal-type pillars 13 are provided at both ends of the truss girders in the longitudinal direction of the aluminum reduction pot The portal-type pillars 13 empoly rectangular steel pipes of 250 mm (the length)×250 mm (the width)×12 mm (the thickness). Supporters 18 for the crane are welded below the connecting beams 19 and over the straight web members 17. Each crane supporter is provided for one straight web member, respectively. The crane supporter is made by channel steel, such as No. 20 according to the Chinese national standard. In this way, the pipe truss girder assembly of the superstructure of the aluminum reduction pot is completed.
In an example, the 400 kA high energy efficiency reduction pot has the total length of 19184 mm and the total height of 6200 mm.
2) Anode Carbon Blocks Assembly
The anode carbon blocks assembly comprises anode rod 24, eight steel stubs, and two carbon blocks 9.
As shown in FIG. 4, the eight steel stubs, two main cross beams 20, and two cant beams 22 are combined together into a horizontal X-shaped structure. both ends of each main cross beam 20 are connected with one small cross beam 21, respectively. The middle part of the small cross beam 21 is vertically fixed to the ends of the main cross beams 20 while the ends of the small cross beams 21 are curved downwards to be connected to the stub 23. Thus, one anode has eight steel stubs 23. As shown in FIG. 4B, the bottom of the stub 23 are fixed to the anode carbon block 9. With the above construction, double-anode structure for a large capacity or a ultra-large capacity aluminum reduction pot is made. During the manufacture of the anode steel stubs, the main cross beams 20, the small cross beams 21, the cant beams 22 and the stubs 23 are assembled together with cast steel per processing. The connected point between the steel stub 23 and the anode rod 24 is located in a center position where the two small cross beams 21 are intercrossed. The connection between the steel stub 23 and the anode rod 24 is achieved by transfer welding by which the aluminum and the steel can be welded together.
The anode rod 24 is made of pure aluminum, and in an example, it has a single weight of 253 kilograms. The lower end of the rod is welded to the aluminum layer with an explosive welding process where the aluminum and the steel are welded together. In an example, the eight steel stubs each has a diameter of 160 mm and a height of 270 mm. The cross beam has a height of 160 mm. The stubs 23 are placed in an anode carbon bowl at a depth of 100 mm. Cast iron is poured into the gap between the anode carbon block and stubs 23 so that they are bonded together. In a specific example, the steel stubs 23 have a current density of 0.104 A/mm²and the weight of about 900 kilograms. Four carbon bowls provided on the surface of each anode carbon block 9 has an inner diameter of 190 mm, a depth of 115 mm, central distance of 360 mm, and a weight of each carbon block about 900 kilograms. The weight of each anode assembly is about 3 tons. There are 24 anode assemblies to be provided on each pot, and the total weight is about 72 tons.
24 anode assemblies in two rows are hung on the two anode busbar beams of the aluminum reduction pot superstructure. It is clamped by a cabin type fixture with a chucking power about 18 tons and torsion torque about 35 kilogram/meter.
3) Anode Busbars, Anode Clamp, and Anode Lifting Device
As shown in FIGS. 1 and 2, the anode busbar 5 of each pot is connected by four cast aluminum busbars of 8350 mm×550 mm×180 mm. Two anode busbars 5 on each long side of the pot are connected by flexible busbars. The anode busbars 5 on both long sides of the pot are connected with aluminum sheet. Corresponding to the power incoming mode of the riser busbars, there are six balance busbars made of the welded aluminum sheet. The other end is connected to the anode rod (made of aluminum) 24 with the anode clamp 6. The total weight of the anode busbar is about 10.8 tons.
Each pot is equipped with an anode lifting device 7 comprised of eight screw elevators. The motor has a power of 13.5 KW. The anode lifting device 7 is mounted over a lateral side of the steel frame of the aluminum reduction pot superstructure, with a stroke of 400 mm, the lifting velocity of 75 mm/min, and lifting capacity of 120 tons, in which the stroke is displayed in an anode stroke counter. The anode busbar lifting device has the total weight of 2.6 tons.
The anode arrangement of the pot is shown as FIG. 5.
There are 24 anode assemblies provided in the aluminum reduction pot cavity 25. Two rows of anode carbon blocks 9 are symmetrically distributed along an axis of longitudinal central line of the aluminum reduction pot. Eight feeding points 26 are provided in the aluminum reduction pot, a centre gap 29 is provided between the two rows of anode carbon blocks opposed with each other, with a width of 50-120 mm. At the feeding point, the gap 27 between two adjacent anode carbon blocks has a width of 40-80 mm. The gap 28 between two adjacent anode carbon blocks where the feeding point is not provided, has a width of 20-50 mm. Compared with the gaps between conventional anode carbon blocks in the existing aluminum reduction pot, it is reduced greatly. The difference between the anode carbon blocks of the present invention and the conventional ones, the carbon block, which has the same size as that of the conventional carbon blocks, has been cut off two corners along the longitudinal end, the cut corner may be a shape of 90° sector, or an isosceles right-triangle.
4) Crust Breaking and Feeding Device
The crust breaking and feeding device 8 comprise of a crust breaking cylinder, a impact head, a constant volume feeder and a feeding hopper. For one aluminum reduction pot, there are seven sets of cylinders in total, and one set of the cylinders is used for aluminum tapping. Six crust-breaking cylinders are provided with the impact heads for breaking the crust, and one remaining cylinder is for aluminum tapping, which has an inner diameter of 160 mm, a stroke of 650 mm, and a striking velocity of 0-80 centimeter/sec. The six crust breaking and feeding cylinders with the impact heads each has an inner diameter of 125 mm, a stroke of 550 mm, and a striking velocity of 0-80 centimeter/sec. Eight constant volume feeder each has an inner diameter of 70 mm. Two constant volume feeders are used for feeding fluoride salt and six for feeding alumina, with a constant volume of 1.6 kilograms and the compressed air pressure of about 0.7 MPa.
Single crust-breaking cylinder for aluminum tapping has a weight of 118 kilograms. Single feeding unit has a weight of 103 kilograms. Single constant volume feeder has a weight of 55 kilograms. The total weight of the crust-breaking and feeding device is about 1.176 tons.
5) Fume Collecting and Exhausting System
The fume collecting and exhausting system of the aluminum reduction pot is shown in FIG. 6A. First of all, anode balance busbar 34 is shifted up from the original position to the central position of the anode busbar 5. The lower portion of the feeding hopper is not welded to the upper chords 15. Instead, it has a V-shaped configuration. The flue branch pipe 32 is placed in the left and right interlayers between the horizontal hood plate 33 and the feeding hopper 30 to form two flue branch pipes 32 in a parallel mode. As shown in FIG. 6B, one is an air inlet with a front opening while the other is an air inlet with a rear opening. The pot fume from two flue branch pipes 32 is gathered into the main flue 12 via flue manifold 35, and then is exhausted into a scrubbing system. The main flue 12 is provided with a control valve 36, which is used to easily adjust negative pressure and fume flow in the two parallel flue branch pipes 32.
6) Anode Rod Sealing Device
As shown in FIG. 7, the anode rod sealing device of the present invention is comprised by a lateral plate 37, a front end plate 38, and a top plate 39. The anode rod is surrounded by the three plates to form a cavity around it.
Firstly, a grating structure is adopted in the three surrounded sides of the anode rod at a front end of the cavity. Secondly, the rear end of the cavity is welded to the side wall of the flue and is connected to the horizontal hood plate 33. Thirdly, the cavity is provided over the horizontal hood plate 33 which is used as a bottom plate.
The manufacture of the sealing device is as follows:
First of all, one or more apertures are drilled at a preset position in the horizontal hood plate of each anode rod. Two lateral plates 37 are welded to the horizontal hood plate 33 and then the top plate 39 is welded thereto. An opening where the rod can be received therein is provided in the front end of the top plate. The sectional dimension of the opening is the same as that of the rod. The top plate and the rear ends of the two lateral plates are welded to side walls of the flue to be communicated with the horizontal flue. When the aluminum reduction pot works, negative pressure is generated around each anode rod due to the suction force from the flue. By this way, the pot fume escaped from the gaps of the anode rod 24 is sucked into the horizontal flue.
7) Air Supply Pipeline and Silencer for Tailed Air from the Crust Breaking and Feeding Device
As shown in FIG. 10, along the direction of the rectangular steel pipe upper chord 15 and the direction of the rectangular steel pipe straight web member 17, crust breaking cylinder 62 with a self-electromagnetic valve, feeding cylinder 63 with a self-electromagnetic valve, blast pipe 64 for crust breaking cylinder and crust breaking cylinder return air pipe 65, a feeding cylinder blast pipe 66 and a return air pipe 67 for the feeding cylinder, and, a backblowing air pipe 68, are connected in sequence. The compressed air pipe 69 connected to the compressed air main pipe is connected to the rectangular steel pipes in the upper portion of the pipe truss girder via a one-way control valve 70. The air is supplied from the rectangular steel pipes to the crust breaking cylinder and the feeding cylinder. Each crust breaking cylinder is connected to the rectangular steel pipes via the blast pipe for crust breaking cylinder and return air pipe for the crust breaking cylinder. Each feeding cylinder is connected to the rectangular steel pipes via blast pipe for the feeding cylinder, the return air pipe for the feeding cylinder, and the backblowing pipe. After the crust breaking and the feeding, the tailed air from the cylinder is led to the rectangular steel pipe of the straight web member via the cylinder tailed air exhausting pipe 71 so as to achieve silencing. Both the crust breaking cylinder and the feeding cylinder have self-electromagnetic valves, which can perform crust breaking and feeding operations through the single-point, the multiple-point and partition control by a pot control box.
One set of cylinder for aluminum crust breaking operation is separately provided at the aluminum tapping end. Alternatively, the crust breaking operation can be separately done by means of a manual control valve 72.
2. The Cathode Structure for the Aluminum Reduction Pot
The cathode structure for the aluminum reduction pot is comprised by a pot shell structure, a cathode lining structure, and a cathode busbar arrangement structure.
1) Pot Shell Structure
The pot shell structure is comprised by two long lateral plates, two short lateral plates, one bottom plate and 29 cradles, the pot body has a boat shape in the bottom of the long lateral plate.
The aluminum reduction pot comprises 29 cradles, in which two are welded to the pot shell and the remaining 27 cradles are provided in the middle bottom of the pot body with a central line distance of 640 mm, and connected to the pot shell so as to support the pot body. Aluminum silicate sheet having a thickness of 10 mm is provided under the bottom of the pot body to reduce the heat conduction from pot body to the cradles, in order to ensure that the stress between the pot body and the cradles is even. There is 15 mm gap between the pot side and the cradles to eliminate the heat conduction between the pot body and the cradles, to decrease the probability of the reduced heating intensity of the cradles.
The upper portion of the pot body has a single-layer enclosure structure, which is connected by the bolt to the cradles, and calcium silicate sheet is sandwiched there between for thermal insulation. The pot body has a inside size of 18740 mm (the length)×4160 mm (the width)×1506 mm (the height), and a weight of about 21.8 tons.
The bottom beam of the cradle is configured to be a H-shaped steel of 496 mm, the lateral beam has a height of 1318 mm. The bottom beam and the lateral beam are welded together by means of steel sheets. One cradle has a weight of 0.795 ton, and 27 cradles have a total weight of 21.5 tons.
The cradles are set on two H-shaped steels each having a height of 300 mm, with an insulation layer being supported on a concrete buttress pier. The pot shell has a weight of about 46.1 tons.
2) Cathode Lining Structure
The cathode lining structure is comprised of cathode carbon blocks 9, and lining structures. Specifically, the cathode lining structure comprises:
2.1) Cathode Carbon Blocks 10 Assembly
The cathode carbon block 10 assembly is comprised of steel collector bars, ramming paste, and cathode carbon blocks.
The cathode carbon block has two grooves, each having 120 mm (in width), 200 mm (in depth), and 250 mm (in center distance of the groove). Four steel collector bars each of 90 mm×180 mm×2100 mm are placed in there between and are connected by ramming with cathode carbon paste. The length of the steel bar is 4460 mm.
The cathode carbon blocks has a weight of 1.456 tons, the four steel collector bars have a weight of 1.059 tons, the cathode paste has a weight of 70 tons, the cathode carbon block assembly has a weight of 2.58 tons, 28 cathode carbon block assemblies in each pot have a total weight of 72.24 tons.
The gaps between these cathode carbon blocks are 30 mm, which are filled by the bottom carbon paste and tamped into a whole. The area occupied by the gaps is 17610 mm×3650 mm².
2.2) Lining Structure
As shown in FIG. 8, the bottom surface of the aluminum reduction pot is provided with the thermal baffle 41, high temperature resistance thermal baffles 42, heat insulation bricks 43, and the bath corrosion resistance bricks 44 at two ends of the pot in sequence. The middle portion thereof is paved with granular refractory material 40. A layer of aluminum sheet or aluminum foil is provided thereon after the granular refractory material 40 is compacted. After installation of heat insulation layer of the pot bottom being finished, the cathode carbon blocks 10 are provided, and cathode steel collector bars 51 surrounded by the refractory insulating papers 50 are inserted into the cathode carbon blocks 10. Steel bar paste 52 is filled into the gaps between the cathode collector bars and the cathode carbon blocks. The cathode steel bars are exposed on the cathode carbon blocks, the cathode steel bars which inside the pot shell are clamped down with the U-type metal plate 46, and then, filled with the refractory castable 47 and the heat insulation felt 45. The side wall of the aluminum reduction pot is built with silicon carbide bricks 48, while both ends of the cathode carbon blocks, the refractory concrete, and the silicon carbide bricks are filled with arc side paste 49.
The side carbon blocks have a weight of about 5.7 tons, the carbon paste has a weight of about 11.6 tons, the bottom refractory insulation layer has a weight of about 31.26 tons, the lower side structure has a weight of about 8.8 tons, and, the lining has a weight of about 129.6 tons.
3) Cathode Busbar Arrangement Structure
As shown in FIGS. 9A and 9B, electricity supply of the aluminum reduction pot is provided by 28 assemblies of cathodes (56 cathode flexible busbars) and 6 riser busbars 61 at the pot side. The distribution proportion of the cathode flexible busbar connected to the 6 riser busbars is 10: 9: 9: 9: 9: 10, respectively. Such allocation both provides convenience for electric balance design and helps relatively balanced magnetic distribution in the liquid aluminum while avoiding excessive vertical magnetic field gradient. There are busbar 53 on power incoming side, end bypass busbar 54, pot bottom busbar 55, local compensation busbar 56, busbar 57 on outgoing side, riser busbar 58, cathode flexible busbar 59 on power incoming side, and, cathode flexible busbar 60 on outgoing side. According to the distribution of the soft busbars, the soft busbar and the vertical busbar are connected by these side busbars or bottom busbars. Further, the short-circuit busbar is provided to form the busbar structure around the aluminum reduction pot.
The magnetic fields at four corners of the aluminum reduction pot are relatively great and usually higher than 40 Gauss. Accordingly, compensation for over current passing the ends is required. Because two corners in the outgoing side have greater resultant magnetic field, each corner in the outgoing side require more compensation current. That is, where a high magnetic field exists, a high compensation is needed, and, where a low magnetic field exists, a low compensation is needed.
It should be indicated that, the present invention is a combination for many inventions. The present invention integrates many innovated technologies including the anode arrangement, sub-section fume collecting and exhausting system, the anode rod sealing technology, and the cathode busbar arrangement structure. The 400 kA high energy efficiency reduction pot according to the present invention has remarkable energy-saving and emission reduction effect, thus having great economic benefits and technical progress over the conventional techniques

Claims

1. A 400 kA high energy efficiency reduction pot, comprising: anode carbon blocks, anode busbars, crust breaking and feeding device, anode lifting device, girders and pillars, pot hooding and exhausting system, cathode busbar arrangement structure, cathode carbon blocks, cathode lining structure and cathode pot shell, the pot is characterized in that:

1) superstructure and portal-type pillars are supported by pipe truss girders structure;

2) anode carbon block has eight steel stubs to be configured in a symmetrical mode;

3) the superstructure has 24 double-anode assemblies or 48 single-anode assemblies, six alumina feeding points, and two fluoride salt feeding points;

4) sub-section fume collecting and exhausting system is installed between a horizontal hood plate and a feeding hopper;

5) a device for sealing the anode rod by means a negative pressure suction is provided;

6) a new lining structure of holding heat on bottom, dispersing heat from side, and adding expansion layer at the cathode end have been designed based on the simulation of the electric field and thermal field;

7) the cathode busbars adopt a non-symmetrical configuration, and six power incoming points on the long side of the pot is provided; and

8) rectangular pipe truss girders are used as both air-supply pipeline above the pot and a silencer for tailed air from the crust breaking and feeding cylinder.

2. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the pipe truss girder structure comprises a connecting beam and crane support provided between two truss girders, characterized in that:

the truss girder has the connecting beam as the top thereof and is comprised of the portal-type pillars, upper chords, lower chords, straight web members, and diagonal web members, all of which take the form of rectangular steel pipes; wherein

1) the straight web members are distributed at a certain space between the upper chords and the lower chords;

2) the inclined chords are placed between the upper chords and the lower chords, at both sides of the straight web members;

3) the straight web members and the inclined chords provided at both sides of the straight web members are arranged to have a umbrella shape or inverted umbrella shape in turn; and

4) the connecting beam is positioned on the tops of the straight web members and is at the same vertical plane with the upper chords.

3. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the anode carbon block assembly has eight symmetrical steel stubs comprising cross beams and stubs, characterized in that: the cross beam is comprised of two main cross beams, two diagonal cross beams, and four small cross beams, wherein:

1) main cross beams and diagonal cross beams are connected in a transverse X-shape;

2) the middle portion of each small cross beam is vertically connected to ends of the main cross beams;

3) both ends of each small cross beam are curved downwards to be connected to the stubs, and the bottom of the stubs is fixed on the carbon block; and

4) a central portion where the two diagonal cross beams are intercrossed with each other is upwardly connected to the anode rod.

4. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said new anode arrangement scheme comprises aluminum reduction pot cavity, anode carbon blocks, and feeding points, characterized in that:

1) all the feeding points are disposed in the position where the four anode carbon block assemblies converge;

2) the gaps between carbon blocks of two adjacent anode assemblies at the feeding points is widened while the gaps between carbon blocks of two adjacent anode assemblies at the non-feeding points is narrowed; and

3) four corners of the anode carbon blocks at the feeding points are cut off to widen the space of the feeding points.

5. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the sub-section fume collecting and exhausting system comprises pot fume flue, a main flue, and a control valve, characterized in that:

1) the flue is disposed inside an interlayer between the horizontal hood plate and the feeding hopper, the lower portion of the feeding hopper is fabricated into V-shaped configuration, instead of welding to the plate girder;

2) the flue is divided into two parallel branch fume pipes and disposed respectively inside the left and right interlayers between the horizontal hood plate and the feeding hopper of the aluminum reduction pot

3) the two branch fume pipes each further comprises front air inlet and rear air inlet;

4) the main flue to which the two branch fume pipes are led is provided with the control valve.

6. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said device for sealing the anode rod by use of a negative pressure suction is provided, the device comprises lateral plate, front end plate, and top plate, characterized in that: the device is a cavity formed by the two lateral plates, top plate, and front end plate and configured to surround around three sides of the anode rod, wherein

1) a grating structure is adopted for the three surrounded sides of the anode rod at the front end of the cavity device;

2) rear end of the cavity is welded to the web beam and communicated to the horizontal flue; and

3) the cavity device is positioned over the horizontal hood plate which is used as a bottom plate.

7. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said new lining structure is designed on basis of simulation of the electric field and thermal field, and the lining structure comprises cathode carbon blocks, cathode steel bar, and bottom refractory material layer, characterized in that:

1) the cathode steel bar is located in the pot shell, and a portion of the steel bar exposed out of the cathode carbon blocks is clamped by a U-shaped metal plate, and then tamped with the refractory castable;

2) the cathode steel bar is wrapped with the refractory insulating paper, and, is filled with steel bar paste;

3) the middle bottom of the cathode carbon is provided with granular refractory material while both ends thereof are provided with refractory bricks; and

4) a straight edge paste structure, instead of an arc edge paste structure, is provided between the cathode carbon blocks and the side wall silicon carbide bricks.

8. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the cathode busbars adopt non-symmetrical configuration and power incoming from six-point on long side of the pot, the cathode busbars comprise a busbar on power incoming side; a busbar on outgoing side, a cathode flexible busbar on power incoming side, a cathode flexible busbar on outgoing side, a pot bottom busbar; and riser busbar, characterized in that:

1) the local compensation busbar is further provided, the local compensation busbar enters the bottom of the pot, and goes out along of the end of the aluminum reduction pot, then, is lifted to a certain height; and

2) 56 cathode flexible busbars and 6 riser busbars are used to supply power for the aluminum reduction pot, the number of the cathode flexible busbars to be connected to the 6 riser busbars is 10: 9: 9: 9: 9: 10, respectively.

9. The 400 kA high energy efficiency reduction pot according to claim 1, wherein said the rectangular pipe truss girder is also used as both the air-supply pipeline and a silencer for tailed air from the crust breaking and feeding cylinder, comprises a compressed air pipeline, a crust breaking cylinder, a feeding cylinder, and aluminum tapping cylinder, characterized in that:

1) the compressed air pipeline is connected to the rectangular steel pipe of the truss in the X direction via an one-way air inlet valve;

2) the rectangular steel pipe of the truss in the X direction is connected to the air inlet pipes of the crust breaking cylinder, the feeding cylinder, and the aluminum tapping cylinder via an electromagnetic control valve; and

3) the tailed air exhausting pipes of the crust breaking cylinder, the feeding cylinder, and the aluminum tapping cylinder are connected to the rectangular steel pipes in the X direction or in the Y direction, via the electromagnetic control valve.