RU2269610C1 - Device for burning anode gases of aluminum electrolyzer - Google Patents

Abstract

FIELD: production of aluminum.

SUBSTANCE: proposed device has burner made in form of three cylinders: upper, middle and lower cylinders which are provided with shoulders between them and holes for suction of air; device is also provided with heat exchanger with fins on upper cylinder, upper and lower air boxes. Upper air box is mounted on fins embracing the upper and middle cylinders over perimeter at spaced relation. Lower air box which is split in construction is mounted on flange of lower cylinder at spaced relation. Air boxes are interconnected by means of vertical risers fitted with throttle valve for control of heated air flow. Upper air box is closed with split washer at the top for making it hermetic.

EFFECT: enhanced efficiency of burning-out of toxic components of anode gas; enhanced operational stability.

4 cl, 1 dwg, 1 tbl

Description

The invention relates to ferrous metallurgy, in particular to the electrolytic production of aluminum, and in particular to devices for burning anode gases.

A device for burning the anode gas of an aluminum electrolyzer, including a burner with slots and a cylindrical heat exchanger, coaxially mounted on the lower flange of the burner [USSR Author's Certificate No. 1102296, class. C 25 C 3/22].

The disadvantage of this device is poor-quality mixing of the anode gas and air, since the device implements only one aerodynamic mixing effect: the flow of air and gas at right angles to each other. In addition, the device does not provide air flow control, as a result of which burners of different electrolyzers operate at different air flow rates. At high air flow rates, it is possible to reduce the combustion temperature of the gas-air mixture and the efficiency of burning out the harmful components of the anode gas. At low air flow rates, the burning of the combustible components of the anode gas is possible, the reform of hydrocarbon components with the release of soot carbon, clogging the burner openings for air supply.

The closest in combination of essential features is a device for burning the anode gas of an aluminum electrolyzer with a double aerodynamic effect [patent RU No. 2203985, cl. C 25 C 3/22]. The gas burner device is made in the form of three cylinders of different sizes, allowing the use of several aerodynamic effects, providing a high-quality mixture of gas and air.

The disadvantage of this device is the lack of constructive solutions for heating air with the heat lost by the surface of the burner. The device also does not provide air flow control, which reduces the efficiency of the burner device.

The objective of the invention is to develop a device that improves the efficiency of burning of harmful components of the anode gas by heating the air and regulating its flow.

To solve the problem in the inventive device for burning the anode gas of an aluminum electrolyzer, including a burner mounted on a tide of a gas collection bell, made in the form of three cylinders - upper, middle and lower with ledges between them, openings for suctioning air and a duct system for heating air the device is equipped with a heat exchanger, consisting of fins made on the upper cylinder, upper and lower air boxes. The upper air box is mounted on the fins and covers with a gap around the perimeter of the upper and middle cylinders of the burner.

The device can be supplemented by private distinguishing features aimed at achieving the stated objectives. The lower air box is detachable and installed with a gap on the flange of the lower cylinder of the burner. The upper and lower air boxes are connected by a vertical riser equipped with a throttle for regulating the flow of heated air entering the burner through openings located in the lower cylinder. The upper air box is closed with a split washer to ensure its tightness.

In relation to the prototype of the proposed device has the following distinctive features. The burner is equipped with a heat exchanger, consisting of fins made on the upper cylinder, upper and lower air boxes. The upper air box is mounted on the fins and covers with a gap around the perimeter of the upper and middle cylinders of the burner. The lower air box is detachable and installed with a gap on the flange of the lower cylinder of the burner.

The upper and lower air boxes are connected by a vertical riser equipped with a throttle for regulating the flow of heated air entering the burner through openings located in the lower cylinder. The upper air box is closed with a split washer to ensure its tightness.

An opening is made in the lower part of the upper air box and the middle cylinder of the burner for visual control of the burner operation and forced ignition of the air-gas mixture.

It is known that air heating is a powerful factor in increasing the temperature in the combustion zone of the anode gas, increasing the efficiency of burning of resinous substances and burning stability by expanding the concentration limits of ignition. In the claimed device, the air is heated when it comes in contact with the surface of the burner and heat exchanger. In addition, the air boxes surrounding the burner act as screens to reduce heat loss from its surface to the environment, which also helps to increase the temperature level inside the burner and, therefore, stabilize the combustion process and the efficiency of burning of resinous substances.

The temperature in the combustion zone of the anode gas and the continuous self-ignition of the gas-air mixture depend on the amount of air entering the burner. Poor in the content of combustible components, the anode gas of the anodes formed from the dry anode mass is especially sensitive to a lack or excess of air. In both cases, flame attenuation and increased emissions of harmful substances into the work area and the environment are possible. The claimed device for regulating air flow provides a throttle valve inside a vertical riser connecting the air box.

The invention is illustrated in the drawing. It shows in section a device for burning the anode gas of an aluminum electrolyzer. A device for burning the anode gas of an aluminum electrolysis cell includes a burner consisting of an upper 1, middle 2, and lower 3 cylinders mounted on a tide of a gas collection bell 4. On the upper cylinder there is a rib 6, on which an upper air box 7 is connected, connected by a vertical riser 8 to the lower air box 9. A throttle valve is installed in a vertical riser 10. The upper air box is closed by a split washer 11. The lower part of the upper air box and the middle cylinder of the burner ying inspection opening 12. The upper cylinder is connected with the burner system 13 flues.

The device operates as follows. Under the action of the vacuum generated by the exhaust fan, the anode gas through the tide of the gas collection bell 4 enters the lower cylinder 3 of the burner and mixes with the heated air sucked in through the openings 5. Ignition of the air-gas mixture. When the gas-air flow enters the middle cylinder 2, a recirculation flow is generated along the entire side wall of the cylinder, which stabilizes the combustion of the gas-air mixture. During recirculation of the flow, the combustible components are in the high temperature zone for a long time, which contributes to their more complete oxidation.

When the gas-air mixture flows from the middle cylinder 2 of a large diameter into the upper cylinder 1 of a smaller diameter, the flow narrows at a distance equal to the height of the middle cylinder. In this case, additional turbulization and mixing of the flow, intensive burning of combustible components occurs. The combustion products through the outlet of the burner are removed into the duct system 13.

Atmospheric air under the influence of the vacuum created by the exhaust fan enters the annular gap between the middle cylinder 2 and the upper air box 7, is heated by the heat lost by the burner into the environment, then it washes the surface of the upper cylinder of the burner 1 and fins 6, is also heated through the vertical riser 8 enters the lower air box 9. Then through the holes 5 located in the lower cylinder 3, the heated air enters the mixing and ignition zone of the air-gas mixture. The combustion of the anode gas is visually controlled by the electrolysis cell through the inspection hole 12, while the flow of heated air is regulated by the throttle valve 10.

The claimed device is tested on a "cold" aerodynamic stand. The temperature field and burning out of harmful components is modeled on a computer. The calculation results are shown in the table.

Table
Heat-technological parameters of burner devices Options Prototype The inventive device Air flow coefficient α one 2 four 2 2 2 2 Heated air temperature, ° С thirty thirty thirty thirty one hundred 150 200 Temperature in the combustion zone, ° С 903 915 905 915 932 995 1045 The content of carbon monoxide at the outlet of the burner, g / nm ³ 0.61 0.53 0.58 0.53 0.3 0.18 0.14 Resinous content on. exit from the burner, g / nm ³ 0,025 0.013 0,020 0.013 0.006 0.004 0.003

From the table it follows that the best results of the burning of the harmful components of the anode gas in the burner design according to the prototype are provided with an air flow coefficient α equal to two. Therefore, all calculations of the claimed device are performed at α = 2. According to the above data, air heating significantly increases the efficiency of burning out the harmful components of the anode gas. Heating the air, for example, to 200 ° C in comparison with the basic version (prototype) allows you to raise the temperature in the combustion zone by 130 ° C, reduce the CO content in the combustion products by 3.7 times, and resinous substances - 4.4 times.

Claims (4)

1. A device for burning the anode gases of an aluminum electrolyzer, containing a burner mounted on the tide of the gas collection bell, made in the form of three cylinders - upper, middle and lower with ledges between them, openings for suctioning air and a duct system, characterized in that for heating the air the device is equipped with a heat exchanger consisting of fins made on the upper cylinder, the upper and lower air boxes, the upper air box mounted on the fins and covers with a gap around etru upper and middle cylinder and the lower air box is mounted with a clearance on the lower flange of the burner cylinder, wherein the upper and lower air boxes connected to a vertical riser for supplying heated air to the burner through openings arranged in the lower cylinder. 2. The device according to claim 1, characterized in that the lower air box is made detachable. 3. The device according to claim 1, characterized in that the vertical riser is equipped with a throttle for regulating the flow of heated air. 4. The device according to claim 1, characterized in that the upper air box is closed with a split washer to ensure its tightness from above.