RU2697148C1 - Device for afterburning of anode gases of aluminum electrolytic cell - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to device for afterburning of anode gases of aluminum electrolysis cell with self-baking anode. Device comprises a gas collection bell, a combustion chamber and branch pipes interacting with gas discharge pipes, the vertical sections of which enter telescopically into the angular sections of the gas collection bell and are equipped with air intake slots, total area f_total which is 0.15…0.20 of the cross-section area F of the pipe, and the horizontal pipe sections telescopically enter the combustion chamber.

EFFECT: higher efficiency of afterburning of anode gases of aluminum electrolyzer formed during operation of aluminum electrolytic cell.

1 cl, 2 dwg

Description

The invention relates to non-ferrous metallurgy, in particular to the electrolytic production of aluminum, and is intended for burning anode gases in burner devices of electrolytic cells with a self-burning anode.

A device is known for afterburning the anode gases of an aluminum electrolyzer, in which the intake slots are equipped with air supply nozzles located relative to the vertical axis of the burner at an angle of 45 ... 60 ° and providing a spiral swirling trajectory of the ignited gas-air mixture in the combustion zone, characterized by an increased contact area of the burned anode gases with air [RF patent No. 2664584, publ. 08/21/2018, bull. No. 24].

A disadvantage of the known device is the need to equip each air intake gap with an air supply pipe, which increases its material consumption.

A device for burning anode gases is known, including a collector with nozzles, vertical sections of which enter telescopically into the corner sections of the gas collection bell of adjacent electrolyzers [ed. USSR Academy of Sciences No. 4666296, publ. 04/05/1975, bull. No. 13]. The efficiency of the afterburning of the anode gases and the resinous substances contained in them increases due to the preliminary heating of the air in the annular gap between the collector and the combustion chamber, reduction of heat transfer through the walls of the combustion chamber and intensive mixing by tangential injection of the anode gas into the collector.

A disadvantage of the known device, taken as a prototype, is the risk of cooling the anode gases as they move through the nozzles to a temperature below the temperature of their self-ignition when mixed with air.

The aim of the invention is to increase the efficiency of afterburning of anode gases generated during operation of an aluminum electrolyzer.

The goal is achieved in that the vertical pipe sections fitted air intake slits, the total area of which is _commonly f ... 0.15 F 0.20 square cross-section pipe and the horizontal pipe sections are telescopically into the combustion chamber.

The presence of air intakes on the pipe ignites the anode gases in it, which increases the residence time of the burned anode gases in the combustion zone.

The ratio of the total area f of the _total air intake slots to the cross-sectional area F of the pipe is justified by the following considerations. According to [Shakhrai S.G., Korostovenko V.V., Rebrik I.I. The improvement of bell gas exhaust systems on powerful Soderberg electrolyzers: a monograph. Krasnoyarsk: IPK SFU, 2010. 146 pp.], The optimal value of the coefficient of excess air α, at which the maximum combustion temperatures of the anode gas are observed in the burner, is α = 1.15. This value of α is ensured when the ratio of the volume of the anode gas V _eng. to the volume of air V _air supplied to the combustion zone V _eng. : At the _air. = 0.15 ... 0.20. Such a ratio of volumes can be achieved by adjusting the ratio of the areas of the intake slots and the cross-sectional area of the pipe. Reducing the total area f of the _total air intake slots <0.15 F _pat. will lead to the fact that the burners will be operated with an excess of air α <1.15 and this will sharply reduce the efficiency of afterburning of the anode gases due to the lack of an oxidizing agent in the combustion zone. Increase in total area f of _total air inlet slots> 0.20 F _pat. - will lead to the fact that the burners will be operated with an excess of air α> 1.15, which will also sharply reduce the efficiency of afterburning of the anode gases due to the cooling of the burner with excessively sucked air.

The telescopic entry of the horizontal pipe sections excludes their mechanical effect on the burner due to their thermal elongation, and the telescopic entry of the vertical pipe section into the gas collection bell and the horizontal pipe into the burner ensures the convenience and speed of replacing the pipe when it burns out without dismantling the burner.

The inventive device for afterburning the anode gases of an aluminum electrolyzer is illustrated graphically. In FIG. 1 shows a general view of the device, FIG. 2 is a section AA of FIG. 2. The device consists of pipes 1 with air inlet slots 2. The pipes are telescopically connected to the gas collection bell 3 of the electrolysers 4 and to the burner 5. The telescopic pipe connection is provided by nozzles 6 located on the gas collection bell and nozzles 7 located on the burner. Unauthorized air leaks are eliminated using a fire-resistant sealing material 8, which is placed in the gaps between the outer walls of the pipes 1 and the inner walls of the pipes 6 and 7.

The inventive device for afterburning the anode gases of an aluminum electrolyzer operates as follows. The anode gases generated in the electrolyzer 4 are collected under the gas collection bell 3, from where they are sent through the pipes 1 to the burner 5. In the pipes, the anode gases, when mixed with the air sucked through the air inlet slots 2, ignite and enter the burner 5 already in the burning state. The input of burning gases through the nozzles 7 ensures their movement in the burner and increase the contact area of the burned anode gases with air. Thus, the afterburning of the anode gases that are not burnt in the pipes is ensured 1. The mechanical effect on the burner of the pipes due to their thermal elongation is eliminated due to their telescopic entry into the gas collection bell through the nozzles 6 and into the burner through the nozzles 7. Unauthorized air intake through the gaps between the outer walls pipes 1 and the inner walls of the nozzles 6 and 7 are eliminated by sealing them with a fire-resistant sealing material 8. The sealing material is necessary to prevent some leaking suction air in the pipes and burner, as this negatively affects the operation of the gas exhaust system as follows:

- increases the load on the pumps by increasing the volume of the gas pump;

- decreases the efficiency of combustion of gases in the pipes 1 and their afterburning in the combustion chamber 5 due to cooling of the latter.

The technical result of the claimed device is to increase the efficiency of afterburning of the anode gases by increasing the time spent in the combustion zone and ensuring the optimal value of the coefficient of excess air α = 1.15, as well as a 2-fold reduction in the number of burners operated in aluminum production buildings.

Claims (2)

1. An apparatus for afterburning gases anode aluminum electrolysis cell comprising a gas gathering bell combustor tubes and interacting with vent pipes, characterized in that the vertical portions of the hot gas pipes are telescopically into angular sections and the gas-collection bell made to the air gaps, the total area which _commonly f is 0.15 ... 0.20 area F of the cross section of the pipe, and the horizontal sections of the exhaust pipes are telescopically included in the combustion chamber. 2. The device according to claim 1, characterized in that between the exhaust pipes and pipes connecting them to the gas collection bell and the burner, there is a sealing material.

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