Petroleum coke filling unit and filling process

Abstract

A 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 travel, - a suction system (6) comprising a suction device (7) and a suction conduit (8) for petroleum coke particles, referred to as fines, the filling unit (1) in which the suction conduit (8) opens on one side into the filling conduit (5) via a suction opening (9), said suction conduit (8) being connected on the other side to the suction device (7) such that the suction system (6) is capable of suctioning the fine particles present in the filling conduit (5). Figure for the abbreviation: Figure 1

Description

Title of the invention: Petroleum coke filling unit and filling method Technical field of the invention

[0001] The invention relates to the field of anode production for primary aluminum production. In particular, the invention relates to petroleum coke filling units for the cells of anode baking furnaces. Technical background

[0002] The industrial production of aluminum from alumina by the Hall-Héroult process is a well-known technique. Generally, it is carried out in an electrolysis plant containing several electrolysis cells. 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 collects at the bottom of the cell.

[0003] The anodes are consumed during the electrolysis reaction, and are replaced regularly.

[0004] Aluminum production plants generally include an anode production unit. The anode production unit comprises a furnace containing cells in the form of trenches cut into the ground. The anodes are first stacked one on top of the other in the cells. Then, petroleum coke is poured into the cells. The petroleum coke helps retain heat in the cells.

[0005] Petroleum coke is dispensed by means of a filling unit comprising a filling conduit. The petroleum coke is in the form of granules of heterogeneous dimensions.

[0006] When petroleum coke is poured into the cells of the baking furnace, the smallest, and therefore lightest, fine particles form a dust mist, which should be eliminated. This dust poses a danger to the safety of the installations and the people working there. Fine particles are typically particles smaller than 100 micrometers.

[0007] Current filling units include a suction system that allows fine particles to be drawn from the end of the filling line as the petroleum coke exits said filling line. The objective is to draw as many fine particles as possible before they spread into the air and form a dust mist.

[0008] Current extraction systems are not entirely satisfactory because a significant quantity of fine particles escapes the extraction system. A dust mist then forms.

[0009] The object of the invention is to remedy these drawbacks by proposing a filling unit whose suction system makes it possible to suction almost all of the fine particles. Summary of the invention

[0010] To this end, a petroleum coke filling unit is proposed firstly for a cell in an anode baking furnace intended for the production of primary aluminum, said cells containing anodes, the filling unit comprising: - a filling conduit in which a flow of petroleum coke moves along a direction of movement, - a suction system comprising a suction device and a suction duct for petroleum coke particles, known as fines, filling unit in which the suction duct opens on one side into the filling duct by a suction opening, said suction duct being connected on the other side to the suction device so that the suction system is able to suction the fine particles present in the filling duct.

[0011] This suction system allows fine particles to be drawn off before the petroleum coke exits the filling duct. Thus, the petroleum coke is conditioned before being poured into the cells of the baking furnace. It was then observed that the petroleum coke no longer produces mist due to fine particles, because suction within the suction duct proves more effective than suction outside of it.

[0012] Various additional features may be provided alone or in combination: - the filling conduit has a lateral opening designed to allow air intake; - the filling unit includes fins arranged opposite the side opening and inside the filling conduit; - 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 about 60°, said first angle being measured in the counter-clockwise direction; - two adjacent fins are located at a first distance from each other of between 10 and 100 millimeters, preferably about 55 millimeters, said first distance being measured along an axis substantially parallel to the direction of movement; - the filling unit includes deflectors arranged opposite the suction opening and inside the filling conduit; - 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 about 30°, said second angle being measured in the clockwise direction; - two adjacent deflectors are located at a second distance from each other of between 30 and 200 millimeters, preferably about 88 millimeters, said second distance being measured along an axis substantially parallel to the direction of movement; - the filling conduit includes a central wall having a petroleum coke inlet orifice, filling unit in which the fins and deflectors are arranged opposite said central wall along an axis substantially parallel to the direction of movement; - the filling unit includes a control device for the cross-section of the side opening and / or includes a control device for the cross-section of the suction opening, these control devices being capable of modifying said cross-sections.

[0013] Secondly, a primary aluminium production plant is proposed comprising a baking furnace and a petroleum coke filling unit in said furnace as previously described.

[0014] Thirdly, a method for filling a cell of an anode baking furnace with petroleum coke is proposed, said cell containing anodes intended for the production of primary aluminum, this method employing a filling unit as previously described, the method comprising: - an operation to circulate petroleum coke in the filling conduit, and - an operation to vacuum fine particles of petroleum coke using the vacuum system, process in which the aspiration of fine particles is carried out directly in the filling duct.

[0015] Various additional features may be provided alone or in combination: - the process includes an operation to modify the cross-section of the side opening and / or the cross-section of the suction opening; - the suction flow rate is set between 1000 and 3000 cubic meters per hour, preferably 1800 cubic meters per hour; - the air speed at the side opening is approximately between 5 and 25 meters per second, preferably 16 meters per second. Brief description of the figures

[0016] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for understanding which reference should be made to the accompanying drawing in which:

[0017] [Fig-1] [Fig.1] is a schematic representation of a filling unit of petroleum coke according to the invention. Detailed description of the invention

[0018] Figure [Fig. 1] shows a petroleum coke filling unit 1.

[0019] The filling unit 1 is intended to pour petroleum coke into a cell 2 of an anode baking furnace 3 4. The anodes 4 are stacked one on top of the other in the cells 2.

[0020] The filling unit 1 includes a filling conduit 5. A flow of petroleum coke moves along a direction of movement represented by an axis X.

[0021] The filling unit 1 includes a suction system 6. The suction system 6 comprises a suction device 7 and a petroleum coke particle suction conduit 8. The suction device 7 is designed to suction small particles, which are referred to as fine particles.

[0022] The filling line 5 has a suction opening 9. The suction line 8 opens into the filling line 5 through the suction opening 9. The suction line 8 is connected at its other end to the suction device 7. Thus, the suction system 6 can draw the fine petroleum coke particles present directly into the filling line 5.

[0023] This suction system 6 allows fine particles to be drawn off before the petroleum coke exits the filling conduit 5. Thus, the petroleum coke is conditioned before being poured into the cells 2 of the baking furnace 3. It was then observed that the petroleum coke no longer produces mist due to fine particles, because suction within the suction conduit 8 proves more effective than suction outside of it.

[0024] 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 complete, a flame is deployed in the walls of the cells. This is achieved by means of burners and fans (not shown).

[0025] Advantageously, the filling conduit 5 includes a lateral opening 10. The lateral opening 10 allows air to enter so as to enable the suction system 6 to function properly.

[0026] Advantageously, the filling unit 1 comprises fins 11. The fins 11 are arranged opposite the lateral opening 10. They are located inside the 5-filling conduit.

[0027] The fins 11 allow the suction airflow from the lateral opening 10 to be diverted. This diversion lengthens the suction airflow through the filling duct 5, thereby improving the capture of fine particles by the suction system 6.

[0028] Advantageously, the fins 11 are in the form of parallel flat plates. They define a first angle α with the X-axis, which is between 45° and 90°. The first angle α is measured in a counterclockwise (trigonometric) direction. In a preferred embodiment, the first angle α is approximately 60°.

[0029] Such an arrangement of the fins 11 makes it possible to deflect the airflow 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 petroleum coke particles is thus optimized according to tests and analyses carried out by the applicant.

[0030] Advantageously, the fins 11 are spaced apart along the X-axis. Two adjacent fins 11 are advantageously spaced apart 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.

[0031] This spacing between the fins 11 allows for an aspiration airflow that enables the capture of fine particles without capturing large particles.

[0032] Advantageously, the filling unit 1 includes deflectors 12. The deflectors 12 are arranged opposite the suction opening 9. The deflectors 12 are located inside the filling conduit 5.

[0033] Advantageously, the deflectors 12 are in the form of parallel flat plates. They define a second angle [3] with the X-axis. The second angle [3] is measured clockwise. Advantageously, the second angle [3] is between 20° and 45°. In a preferred embodiment, the second angle [3] is approximately 30°.

[0034] The petroleum coke particles strike the deflectors 12 during their passage through the filling conduit 5. The deflectors 12, arranged in this way, allow the suction system 6 to capture only the fine particles. Indeed, upon striking the deflectors 12, the fine particles are drawn in through the suction opening 9 by the suction airflow. The larger particles, under the effect of gravity, resume their path along the X-axis.

[0035] Advantageously, the deflectors 12 are spaced apart from each other along the X axis. Two adjacent deflectors 12 are advantageously spaced apart 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.

[0036] This spacing between the deflectors 12 allows for an aspiration airflow that enables the capture of fine particles without capturing large particles.

[0037] Advantageously, the filling conduit 5 comprises an outer casing. The outer casing comprises a lateral wall 13 and a central wall 14. The central wall 14 is arranged perpendicular to the lateral wall 13. The central wall 14 has a petroleum coke inlet 15. Thus, the filling conduit 5 is connected to a petroleum coke inlet line 16. The petroleum coke inlet line 16 opens into the filling conduit 5 through the inlet 15.

[0038] Advantageously, the fins 11 and the deflectors 12 are arranged opposite the central wall 14, along the X axis.

[0039] Such an arrangement makes it possible not to obstruct the filling conduit 5.

[0040] Advantageously, the filling unit 1 includes a control device 17 for the section of the lateral opening 10.

[0041] Advantageously, the filling unit 1 may include a device 17 for controlling the section of the suction opening 9.

[0042] In the embodiment shown, the filling unit 1 includes only a control device 17 for the cross-section of the lateral opening 10 and is devoid of a control device 17 for the cross-section of the suction opening 9.

[0043] These devices allow the suction airflow velocity to be varied locally, at the level of the lateral opening 10 and / or the suction opening 9. Thus, it is possible to vary the flow velocity to adapt the suction to the petroleum coke being used. By increasing the suction airflow velocity in the filling duct 5, it is possible to suction larger particles, and vice versa.

[0044] In what follows, a petroleum coke filling process will be described. This is a petroleum coke filling process in a cell 2 of an anode baking furnace 3. The cell 2 comprises anodes 4 stacked one on top of the other, and intended for the production of primary aluminum.

[0045] The process implements the filling unit 1 described above.

[0046] The process includes an operation of circulating petroleum coke in the filling line 5. The petroleum coke is initially stored in a hopper. The petroleum coke then flows down a feed line and finally a filling line to be discharged into a cell 2 of the anode baking furnace 4.

[0047] The process includes a fine particle suction operation. This operation is carried out using the suction system 6. During this step, a suction airflow 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.

[0048] Thus the aspiration of fine particles is carried out directly in the filling line, which improves the capture of fine particles compared to current processes.

[0049] Advantageously, the method includes an operation of modifying the section of the lateral opening 10 and / or the section of the suction opening 9.

[0050] This operation is carried out when a fine particle fog becomes too heavy. In order to reduce the fog density, the cross-section of the lateral opening 10 is adjusted by means of the cross-section control device 17.

[0051] 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.

[0052] A flow rate chosen within this range allows for the capture of fine particles and avoids fog at the outlet of the filling conduit 5.

[0053] Advantageously, the air velocity at the lateral opening 10 is substantially between 5 and 25 meters per second. In a preferred embodiment, the velocity is approximately 16 meters per second.

[0054] A speed chosen in this range allows the capture of fine particles in particular those with a dimension less than 100 micrometers and which are those likely to cause a fog at the outlet of the filling conduit 5.

Claims

Demands

1. A unit (1) for filling petroleum coke into a cell (2) of an anode (4) baking furnace (3) 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 in 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, the filling unit (1) in which the suction conduit (8) opens on one side into the filling conduit (5) by a suction opening (9), said suction conduit (8) being connected on the other side to the suction device (7) so that the suction system (6) is capable of suctioning the fine particles present in the filling conduit (5).

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

3. Filling unit (1) according to claim 2 wherein it comprises fins (11) arranged opposite the lateral opening (10) 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. Filling unit (1) according to any one of claims 3 or 4 in which 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 de- 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°, said second (|3) angle being measured in the clockwise direction.

8. Filling unit (1) according to any one of claims 6 or 7 wherein, 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 travel.

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, such control devices being capable of modifying said cross-sections.

11. 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. A 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, said method employing a filling unit (1) according to any one of claims 1 to 9, the method comprising: - an operation of circulating petroleum coke in the filling conduit (5), and - an operation of suctioning fine particles of petroleum coke by means of the suction system (6), the method wherein the suction of fine particles is carried out directly in the filling conduit (5).

13. A 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 of the suction opening section (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 wherein the air velocity at the lateral opening (10) is substantially between 5 and 25 meters per second, preferably 16 meters per second.

Images