Petroleum coke filling unit and filling method

Abstract

The invention relates to a unit (1) for filling petroleum coke into a cell (2) of a furnace (3) for baking anodes (4) intended for the production of primary aluminium, the cells (2) containing anodes (4), the filling unit (1) comprising: - a filling pipe (5) in which a flow of petroleum coke moves in a direction of movement; - a suction system (6) comprising a suction device (7) and a pipe (8) for sucking up particles of petroleum coke, referred to as fines, in which filling unit (1) the suction pipe (8) opens on the one hand into the filling pipe (5) via a suction opening (9), the suction pipe (8) being connected on the other hand to the suction device (7) such that the suction system (6) is able to suck up the fine particles present in the filling pipe (5).

Description

[0001] DESCRIPTION

[0002] TITLE: Petroleum coke filling unit and filling process

[0003] Technical field of the invention

[0004] The invention relates to the field of production of anodes for the production of primary aluminium. In particular, the invention relates to units for filling petroleum coke into the cells of anode baking furnaces.

[0005] Technical background

[0006] The industrial production of aluminum from alumina using the Hall-Héroult process is a well-known technique. It is generally carried out in an electrolysis facility in which several electrolytic cells are installed. Each cell is filled with an electrolytic bath including cryolite in which alumina is dissolved. Carbon anodes are partially immersed in the electrolytic bath and dissolve to produce liquid aluminum, which accumulates at the bottom of the cell.

[0007] The anodes are consumed during the electrolysis reaction and are replaced regularly.

[0008] Aluminum production plants generally include an anode production unit. The anode production unit consists of a furnace containing cells in the form of trenches dug into the ground. The anodes are first stacked on top of each other in the cells. Then, petroleum coke is poured into the cells. The petroleum coke helps retain heat in the cells.

[0009] Petroleum coke is discharged by means of a filling unit comprising a filling pipe. Petroleum coke is in the form of granules of heterogeneous dimensions.

[0010] When petroleum coke is poured into the furnace cells, the smallest, and therefore lightest, fine particles form a dust mist, which is best avoided. This dust poses a safety hazard to the facilities and the people who work there. Fine particles are typically particles smaller than 100 micrometers.

[0011] Current filling units include a suction system that allows fine particles to be sucked out of the end of the filling pipe as the petroleum coke exits the filling pipe. The goal is to suck out as many fine particles as possible before they become airborne and form a dust mist.

[0012] Current vacuum systems are not entirely satisfactory because a significant quantity of fine particles escape the vacuum system. A dust mist then forms.

[0013] The object of the invention is to remedy these drawbacks by proposing a filling unit whose suction system allows almost all fine particles to be sucked up.

[0014] Summary of the invention To this end, there is proposed firstly a unit for filling petroleum coke into a cell of an anode baking furnace intended for the production of primary aluminium, said cells containing anodes, the filling unit comprising

[0015] - a filling conduit in which a flow of petroleum coke moves in a direction of movement,

[0016] - a suction system comprising a suction device and a suction conduit for petroleum coke particles, called fines, filling unit in which the suction conduit opens on the one hand onto the filling conduit via a suction opening, said suction conduit being connected on the other hand to the suction device so that the suction system is capable of sucking up the fine particles present in the filling conduit.

[0017] This suction system allows fine particles to be sucked out before the petroleum coke leaves the filling pipe. This way, the petroleum coke is conditioned before being poured into the cells of the cooking furnace. It was then found that the petroleum coke no longer produces mist due to fine particles, because suction in the suction pipe is more effective than suction outside it.

[0018] Various additional features may be provided alone or in combination:

[0019] - the filling duct has a side opening intended to allow air intake;

[0020] - the filling unit comprises fins arranged opposite the side opening and inside the filling duct;

[0021] - the fins are in the form of flat plates parallel to each other and defining a first angle with the direction of movement, between 45° and 90°, preferably approximately 60°, said first angle being measured in the counterclockwise direction;

[0022] - two adjacent fins are located at a first distance from each other of between 10 and 100 millimeters, preferably approximately 55 millimeters, said first distance being measured along an axis substantially parallel to the direction of movement;

[0023] - the filling unit comprises deflectors arranged opposite the suction opening and inside the filling duct;

[0024] - the deflectors are in the form of flat plates parallel to each other and defining a second angle with the direction of movement, between 20° and 45°, preferably approximately 30°, said second angle being measured clockwise;

[0025] - two adjacent deflectors are located at a second distance from each other of between 30 and 200 millimeters, preferably approximately 88 millimeters, said second distance being measured along an axis substantially parallel to the direction of movement;

[0026] - the filling duct comprises a central wall comprising a petroleum coke inlet orifice, filling unit in which the fins and the deflectors are arranged opposite said central wall along an axis substantially parallel to the direction of movement;

[0027] - the filling unit comprises a device for controlling the section of the lateral opening and / or comprises a device for controlling the section of the suction opening, these control devices being capable of modifying said sections.

[0028] Secondly, a primary aluminum production plant is proposed comprising a baking furnace and a petroleum coke filling unit in said furnace as previously described.

[0029] Thirdly, a method is proposed for filling petroleum coke into a cell of an anode baking furnace, said cell containing anodes intended for the production of primary aluminium, this method using a filling unit as previously described, the method comprising:

[0030] - an operation of putting petroleum coke into circulation in the filling pipe, and

[0031] - an operation of suctioning fine particles of petroleum coke by means of the suction system, a process in which the suction of fine particles is carried out directly in the filling pipe.

[0032] Various additional features may be provided alone or in combination:

[0033] - the method comprises an operation of modifying the section of the lateral opening and / or the section of the suction opening;

[0034] - the suction flow rate is set between 1000 and 3000 cubic meters per hour, preferably 1800 cubic meters per hour;

[0035] - the air speed at the side opening is approximately between 5 and 25 meters per second, preferably 16 meters per second.

[0036] Brief description of the figures

[0037] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which one will refer to the attached drawing in which:

[0038] [Fig 1] Figure 1 is a schematic representation of a petroleum coke filling unit according to the invention.

[0039] Detailed description of the invention

[0040] Figure 1 shows a petroleum coke filling unit 1. The filling unit 1 is intended to pour petroleum coke into a cell 2 of a furnace 3 for baking anodes 4. The anodes 4 are stacked on top of each other in the cells 2.

[0041] The filling unit 1 comprises a filling conduit 5. A flow of petroleum coke moves in a direction of movement represented by an X axis.

[0042] The filling unit 1 comprises a suction system 6. The suction system 6 comprises a suction device 7 and a pipe 8 for suctioning petroleum coke particles. The suction device 7 is intended to suck up small particles, these particles are called fine particles.

[0043] The filling conduit 5 has a suction opening 9. The suction conduit 8 opens onto the filling conduit 5 through the suction opening 9. The suction conduit 8 is connected at its other end to the suction device 7. Thus the suction system 6 can suck up the fine particles of petroleum coke present directly in the filling conduit 5.

[0044] This suction system 6 makes it possible to suck up the fine particles before the petroleum coke leaves the filling pipe 5. Thus the petroleum coke is conditioned before being poured into the cells 2 of the cooking furnace 3. It was then found that the petroleum coke no longer produces mist due to the fine particles, because suction in the suction pipe 8 proves to be more effective than suction outside it.

[0045] When a cell 2 is filled with petroleum coke, the filling unit 1 is moved to another cell 2 and so on. Once the filling operations are completed, a flame is deployed in the walls of the cells. This is achieved by means of burners and fans not shown.

[0046] Advantageously, the filling duct 5 comprises a lateral opening 10. The lateral opening 10 allows an air intake so as to allow the suction system 6 to operate properly. Advantageously, the filling unit 1 comprises fins 11. The fins 11 are arranged opposite the lateral opening 10. They are located inside the filling duct 5.

[0047] The fins 11 allow the suction air flow coming from the lateral opening 10 to be diverted. This diversion allows the length of the suction air flow passing through the filling duct 5 to be extended, thereby improving the capture of fine particles by the suction system 6.

[0048] Advantageously, the fins 11 are in the form of flat plates parallel to each other. They define a first angle α with the X axis of between 45° and 90°. The first angle α is measured in the counterclockwise (trigonometric) direction. In a preferred embodiment, the first angle α is approximately 60°.

[0049] Such an arrangement of the fins 11 makes it possible to deflect the air flow in the direction of the X axis, and not against the direction of movement of the petroleum coke in the filling conduit 5. The capture of fine particles of petroleum coke is then optimized according to tests and analyses carried out by the applicant.

[0050] Advantageously, the fins 11 are spaced from each other along the X axis. Two adjacent fins 11 are advantageously spaced from each other by a first distance a measured along the X axis and between 10 and 100 millimeters. In a preferred embodiment, the first distance a is approximately 55 millimeters.

[0051] This spacing between the fins 1 1 makes it possible to obtain a suction air flow allowing the capture of fine particles without capturing large particles.

[0052] Advantageously, the filling unit 1 comprises deflectors 12. The deflectors 12 are arranged opposite the suction opening 9. The deflectors 12 are located inside the filling conduit 5.

[0053] Advantageously, the deflectors 12 are in the form of flat plates parallel to each other. They define a second angle p with the X axis. The second angle P is measured clockwise. Advantageously, the second angle P is between 20° and 45°. In a preferred embodiment, the second angle P is approximately 30°.

[0054] The petroleum coke particles strike the deflectors 12 during their journey in the filling conduit 5. The deflectors 12 thus arranged allow the suction system 6 to capture only the fine particles. Indeed, by striking the deflectors 12, the fine particles are sucked in through the suction opening 9 thanks to the suction air flow. The larger particles, under the effect of gravity, resume their path along the X axis.

[0055] Advantageously, the deflectors 12 are spaced from each other along the X axis. Two adjacent deflectors 12 are advantageously spaced from each other by a second distance b measured along the X axis and between 30 and 200 millimeters. In a preferred embodiment, the second distance b is approximately 90 millimeters. This spacing between the deflectors 12 makes it possible to obtain a suction air flow making it possible to obtain the capture of fine particles without capturing large particles.

[0056] Advantageously, the filling conduit 5 comprises an outer casing. The outer casing comprises a side wall 13 and a central wall 14. The central wall 14 is arranged perpendicular to the side wall 13. The central wall 14 comprises a petroleum coke inlet orifice 15. Thus, the filling conduit 5 is connected to a petroleum coke inlet pipe 16. The petroleum coke inlet pipe 16 opens into the filling conduit 5 via the inlet orifice 15.

[0057] Advantageously, the fins 11 and the deflectors 12 are arranged opposite the central wall 14, along the axis X.

[0058] Such an arrangement makes it possible not to obstruct the filling conduit 5.

[0059] Advantageously, the filling unit 1 comprises a device 17 for controlling the section of the lateral opening 10.

[0060] Advantageously, the filling unit 1 can comprise a device 17 for controlling the section of the suction opening 9.

[0061] In the embodiment shown, the filling unit 1 only comprises a device 17 for controlling the section of the lateral opening 10 and is devoid of a device 17 for controlling the section of the suction opening 9.

[0062] These devices make it possible to vary the speed of the suction air flow locally, at the lateral opening 10 and / or the suction opening 9. Thus, it is possible to vary the speed of the flow to adapt the suction to the petroleum coke used. By increasing the speed of the suction air flow in the filling duct 5, it is possible to suck up larger particles and vice versa.

[0063] In the following, a method for filling petroleum coke will be described. This is a method for filling petroleum coke into a cell 2 of a furnace 3 for baking anodes 4. The cell 2 comprises anodes 4 stacked on top of each other, and intended for the production of primary aluminum.

[0064] The method implements the previously described filling unit 1.

[0065] The method comprises an operation of circulating petroleum coke in the filling conduit 5. The petroleum coke is initially stored in a hopper. The petroleum coke then descends a feed conduit and finally a filling conduit in order to be poured into a cell 2 of anode baking furnace 4.

[0066] The method comprises an operation of suctioning the fine particles. This operation is carried out by means of the suction system 6. During this step, a suction air flow extending from the lateral opening 10 to the suction opening 9 captures the fine particles in the filling duct 5, these fine particles being conveyed to the suction duct 8.

[0067] Thus, the suction of fine particles is carried out directly in the filling pipe, which improves the capture of fine particles compared to current processes.

[0068] Advantageously, the method comprises an operation of modifying the section of the lateral opening 10 and / or the section of the suction opening 9. This operation is carried out when a mist of fine particles becomes too large. In order to reduce the density of the mist, the section of the lateral opening 10 is adjusted by means of the section control device 17.

[0069] Advantageously, the suction flow rate in the suction duct is set between 1000 and 3000 cubic meters per hour. In a preferred embodiment, the suction flow rate is 1800 cubic meters per hour.

[0070] A flow rate chosen within this range makes it possible to capture fine particles and avoid mist at the outlet of the filling pipe 5.

[0071] Advantageously, the air speed at the lateral opening 10 is substantially between 5 and 25 meters per second. In a preferred embodiment, the speed is approximately 16 meters per second.

[0072] A speed chosen in this interval makes it possible to obtain the capture of fine particles, in particular those having a dimension less than 100 micrometers and which are those likely to cause fog at the outlet of the filling conduit 5.

Claims

DEMANDS 1. Unit (1) for filling petroleum coke into a cell (2) of an anode (4) baking furnace (3) intended for the production of primary aluminum, said cells (2) containing anodes (4), the filling unit (1) comprising: - a filling conduit (5) in which a flow of petroleum coke moves along a direction of movement, - a suction system (6) comprising a suction device (7) and a suction conduit (8) for petroleum coke particles, referred to as fines, a filling unit (1) in which the suction conduit (8) opens on one side into the filling conduit (5) by an opening (9) suction, said suction duct (8) being connected on the other hand to the suction device (7) so that the suction system (6) is capable of suctioning the fine particles present in the filling duct (5).

2. Filling unit (1) according to claim 1 in which the filling conduit (5) has a lateral opening (10) intended to allow air intake.

3. Filling unit (1) according to claim 2, wherein it comprises fins (11) arranged opposite the opening (10) lateral and inside the filling conduit (5).

4. Filling unit (1) according to claim 3 in which the fins (11) are in the form of flat plates parallel to each other and defining a first angle (a) with the direction of movement, between 45° and 90°, preferably about 60°, said first angle (a) being measured in the counterclockwise direction.

5. A filling unit (1) according to any one of claims 3 or 4, wherein two adjacent fins (11) are situated at a first distance (a) from each other of between 10 and 100 millimeters, preferably about 55 millimeters, said first distance (a) being measured along an axis substantially parallel to the direction of movement.

6. Filling unit (1) according to any one of the preceding claims wherein it comprises deflectors (12) arranged opposite the suction opening (9) and inside the filling conduit (5).

7. Filling unit (1) according to claim 6 in which the deflectors (12) are in the form of flat plates parallel to each other and defining a second angle with the direction of movement, between 20° and 45°, preferably about 30°, led it second (P) angle being measured in the clockwise direction.

8. Filling unit (1) according to any one of claims 6 or 7 in which two adjacent deflectors (12) are located at a second distance (b) from each other of between 30 and 200 millimeters, preferably about 88 millimeters, said second distance (b) being measured along an axis substantially parallel to the direction of movement.

9. Filling unit (1) according to any one of claims 3 to 8 in which the filling conduit (5) comprises a central wall (14) having a petroleum coke inlet orifice (15), filling unit (1) in which the fins (11) and the deflectors (12) are arranged opposite said central wall (14) along an axis substantially parallel to the direction of travel.

10. Filling unit (1) according to any one of the preceding claims, wherein it comprises a device (17) for controlling the cross-section of the side opening and / or comprises a device for controlling the cross-section of the suction opening, these control devices being capable of modifying said cross-sections. 1 1. Primary aluminium production plant comprising a baking furnace (3) and a petroleum coke filling unit (1) in said furnace (3) according to any one of the preceding claims.

12. Method for filling petroleum coke into a cell (2) of an anode baking furnace, said cell (2) containing anodes (4) intended for the production of primary aluminium, this process employing a filling unit (1) according to any one of claims 1 to 9, the process comprising: - an operation to put petroleum coke into circulation in the conduit (5) of filling, and - an operation of suctioning fine particles of petroleum coke by means of the suction system (6), process in which the suction of fine particles is carried out directly in the filling conduit (5).

13. Method according to claim 12, implementing a filling unit (1) according to claim 10, the method comprising an operation of modifying the cross-section of the lateral opening (10) and / or the cross-section of the suction opening (9).

14. A method according to any one of claims 12 or 13 wherein the suction flow rate is set between 1000 and 3000 cubic meters per hour, preferably 1800 cubic meters per hour.

15. A method according to any one of claims 12 to 14 in which, the air velocity at the level of the lateral opening (10) is substantially between 5 and 25 meters per second, preferably 16 meters per second.

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