Electrolytic aluminum carbon anode roasting flue gas ultra-low emission purification equipment

Abstract

The utility model discloses electrolytic aluminum carbon anode roasting flue gas ultra-low emission purification equipment, relates to the field of general physical or chemical methods or devices, and aims to purify various pollutants contained in roasting flue gas and realize ultra-low emission of the roasting flue gas. According to the technical scheme, the electrolytic aluminum carbon anode roasting flue gas ultra-low emission purification equipment comprises a non-catalytic reduction denitration device, a desulfurizing tower, a dust remover, a heat storage type catalytic combustion device and a calcining device, and the non-catalytic reduction denitration device comprises a roasting furnace and an ejector for spraying a denitration agent into the roasting furnace. A flue gas outlet of the roasting furnace is connected with a flue gas inlet of the desulfurizing tower, a flue gas outlet of the desulfurizing tower is connected with the dust remover, a flue gas outlet of the dust remover is connected into the heat accumulating type catalytic combustion device, a flue gas outlet of the heat accumulating type catalytic combustion device is connected into the chimney, and a dust outlet of the dust remover is respectively connected with the desulfurizing tower and the calcining device. The carbon anode roasting flue gas purification device is used for purifying carbon anode roasting flue gas.

Description

Technical Field

[0001] The utility model relates to the field of general physical or chemical methods or devices, in particular to gas separation, and specifically to a device for purifying flue gas from baking carbon anodes of electrolytic aluminum. Background Art

[0002] In the electrolytic aluminum industry, asphalt, calcined coke, and residual anodes are kneaded, formed, and other processes to produce raw anodes. The raw anodes are then calcined at high temperatures to become carbon anodes. The carbon anodes are assembled with anode guide rods and installed in electrolytic cells for use as electrolytic anodes. The roasting flue gas produced by the raw anodes during the high-temperature roasting stage contains a variety of pollutants such as nitrogen oxides, sulfur dioxide, fluorides, asphalt smoke, and particulate matter. The roasting flue gas must be purified to meet the standards before it can be discharged into the atmosphere. The "Technical Guidelines for the Formulation of Emergency Emission Reduction Measures for Key Industries in Heavy Pollution Weather" (2020 Revised Edition) issued by the Ministry of Ecology and Environment requires that during the heavy pollution warning period, only enterprises with environmental protection performance grade A in all provinces and cities across the country can reduce emissions on their own; for carbon system environmental protection performance grade A enterprises, they are required to have denitrification and organic matter treatment process technologies, and major pollutants such as sulfur dioxide, particulate matter, and nitrogen oxides must reach nitrogen oxides below 50mg / Nm 3 、SO2 is less than 30mg / Nm 3 , particulate matter is less than 10mg / Nm 3 Ultra-low emission standards.

[0003] At present, the existing mature methods for purifying the roasting flue gas generated by high-temperature roasting of raw anodes mainly include flue gas incineration, electrostatic tar collector purification, electrostatic tar collector + alumina adsorption combined purification, electrostatic tar collector + carbon powder adsorption combined purification, pure alumina adsorption purification, pure carbon powder adsorption purification and other technologies. In recent years, the roasting flue gas purification method has begun to add a desulfurization system, mainly adding a limestone-gypsum wet desulfurization system or a semi-dry desulfurization system to the back end of the original asphalt smoke purification process. The existing roasting flue gas purification method does not remove nitrogen oxides, asphalt smoke, etc. at the same time and meet the ultra-low emission standards. The selective catalytic reduction reaction has high investment, operating costs, and liquid ammonia safety risks. The selective non-catalytic reduction reaction has low denitrification efficiency and cannot achieve ultra-low emissions. The electrostatic tar purification method is flammable and explosive, and the asphalt is not easy to clean; RTO construction investment is large and the operating cost is high. The optimal adsorption temperature range of activated carbon for catalytic combustion (RCO) adsorbent is narrow (0-50°C), and the desulfurization wastewater and desulfurization by-products generated by wet desulfurization are difficult to be harmlessly treated.

[0004] The patent with application publication number CN 111282416 A discloses a flue gas purification device and method for baking carbon anode of electrolytic aluminum, which is used for the purification of flue gas of baking carbon anode of electrolytic aluminum. From the upstream to the downstream of the flue gas transmission, it includes a selective non-catalytic reduction denitrification device, an adsorption detarring device and a semi-dry desulfurization device. Among them, the selective non-catalytic reduction denitrification device is used to remove nitrogen oxides from pollutants; the adsorption detarring device is used to remove tar from pollutants and remove most of the particulate matter at the same time; the semi-dry desulfurization device is used to remove sulfur dioxide from pollutants and remove fluorides and remaining particulate matter at the same time. Baking flue gas often also contains asphalt smoke and volatile organic compounds. The purification equipment and method disclosed in the patent do not purify asphalt smoke and volatile organic compounds (VOCs). In addition, the dust receiving bin in the semi-dry desulfurization device is used to collect dust generated by semi-dry desulfurization. The patent does not mention how to treat these dusts harmlessly. Utility Model Content

[0005] The utility model provides ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas, aiming at purifying various pollutants contained in the baking flue gas and realizing ultra-low emission of the baking flue gas.

[0006] The technical scheme adopted by the utility model is: ultra-low emission purification equipment for electrolytic aluminum carbon anode roasting flue gas, including a non-catalytic reduction denitrification device, a desulfurization tower, a dust collector, a heat storage catalytic combustion device and a calcining device, the non-catalytic reduction denitrification device includes a roasting furnace and an injector for spraying a denitrification agent into the roasting furnace, the flue gas outlet of the roasting furnace is connected with the flue gas inlet at the bottom of the desulfurization tower through a pipeline, the desulfurization tower is provided with a desulfurization agent supplier, the flue gas outlet at the top of the desulfurization tower is connected with the dust collector through a pipeline, the flue gas outlet of the dust collector is connected with the heat storage catalytic combustion device through a pipeline, the flue gas outlet of the heat storage catalytic combustion device is connected with a chimney through a pipeline, and an induced draft fan is also provided on the pipeline between the heat storage catalytic combustion device and the chimney; the dust outlet of the dust collector is connected with a tee, and two branch pipes of the tee are respectively connected with the dust inlet of the desulfurization tower and the inlet of the calcining device.

[0007] In order to reduce the nitrogen oxides generated during the roasting process of the roasting furnace, further: the burner in the roasting furnace is a low-nitrogen burner.

[0008] In order to improve the denitration efficiency of the non-catalytic reduction denitration device, the ejector uses compressed air as a power to inject dry powder denitration agent into the roasting furnace. Specifically: the ejector has a compressed gas connector and is also connected to the dry powder denitration agent silo.

[0009] The dust collector is used to physically filter the roasting flue gas after desulfurization. Specifically, the dust collector is a bag dust collector.

[0010] In order to facilitate the collection of desulfurization by-products, further: a branch pipe of the tee at the dust outlet of the dust collector is connected to the inlet of the desulfurization ash bin, and the outlet of the desulfurization ash bin is connected to the calcining device through a pipeline.

[0011] The calcining device converts the hazardous wastes such as asphalt and organic matter in the desulfurization by-products into general solid waste. Specifically: the calcining device is a rotary kiln or an incinerator.

[0012] The temperature of the roasting flue gas after desulfurization is relatively high, so in order to avoid the need to cool the roasting flue gas to reach the effective temperature range of activated carbon adsorption, the adsorption bed of the regenerative catalytic combustion device is a zeolite molecular sieve.

[0013] In order to ensure the smoothness of the pipeline between the thermal storage catalytic combustion device and the chimney, further: two induced draft fans are provided on the pipeline between the thermal storage catalytic combustion device and the chimney, and the two induced draft fans are arranged in parallel.

[0014] The beneficial effects of the utility model are as follows: the roasting flue gas is denitrated in the roasting furnace, then enters the desulfurization tower for desulfurization, and then is filtered by the dust collector. The filtered flue gas enters the regenerative catalytic combustion device, which purifies the asphalt smoke and volatile organic matter in the roasting flue gas. The desulfurization by-products enter the desulfurization ash bin through the dust outlet of the dust collector, and then enter the calcination device. The calcination device converts the desulfurization by-products containing asphalt, organic matter and other hazardous wastes into general solid wastes through calcination. The utility model can treat nitrogen oxides, sulfur dioxide, particulate matter, asphalt smoke, and fluoride at one time and achieve ultra-low emissions. At the same time, it can harmlessly treat the desulfurization by-products, which can significantly reduce the pollutant emission value and meet the A-level requirements for carbon system environmental protection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an embodiment of the utility model of ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas.

[0016] Reference numerals: roasting furnace 1, ejector 2, desulfurization tower 3, desulfurization agent supplier 31, dust collector 4, regenerative catalytic combustion device 5, induced draft fan 6, chimney 7, desulfurization ash bin 8, calcining device 9. DETAILED DESCRIPTION

[0017] The utility model will be further described below in conjunction with the accompanying drawings.

[0018] like Figure 1 As shown, the ultra-low emission purification equipment for flue gas from carbon anode roasting of electrolytic aluminum of the utility model comprises a non-catalytic reduction denitrification device, a desulfurization tower 3, a dust collector 4, a heat storage catalytic combustion device 5 and a calcination device 9.

[0019] The non-catalytic reduction denitration device includes a roasting furnace 1 and an injector 2 for injecting a denitrifying agent into the roasting furnace 1, and the roasting furnace 1 is provided with a burner. In order to reduce the nitrogen oxides generated during the roasting process of the roasting furnace 1, the burner in the roasting furnace 1 is a low-nitrogen burner. The raw anode generates roasting flue gas during the roasting process in the roasting furnace, and the roasting flue gas is denitrated in the fire channel of the roasting furnace 1 through a low-nitrogen burner combined with dry non-catalytic reduction reaction denitration. In order to improve the denitration efficiency of the non-catalytic reduction denitration device, the injector 2 uses compressed air as a power to inject a dry powder denitrifying agent into the roasting furnace 1, that is, the injector 2 has a compressed gas connector, which is used to connect an external compressed gas source, and the injector 2 is also connected to a dry powder denitrifying agent silo. The dry powder denitrifying agent silo is used to temporarily store dry powder denitrifying agents, and the denitrifying agent is generally urea. The injector 2 uses compressed air to spray the dry powder denitrification agent into the fire channel of the calcining furnace 1 at 800-1100°C. The dry powder denitrification agent will be completely pyrolyzed to generate gaseous reduced hydrocarbons. The organic decomposition products react with NO x Selective non-catalytic reduction reaction to reduce NO x Reduced to N2 and H2 O. In order to improve the denitration rate, the burner in the roasting furnace 1 can be moved periodically as the combustion area of ​​the flue gas volatiles moves forward.

[0020] The flue gas outlet of the roasting furnace 1 is connected to the flue gas inlet at the bottom of the desulfurization tower 3 through a pipeline. The desulfurization tower 3 is provided with a desulfurizer supplier 31. The flue gas outlet at the top of the desulfurization tower 3 is connected to the dust collector 4 through a pipeline. The dust outlet of the dust collector 4 is connected to a tee. The two branches of the tee are respectively connected to the dust inlet of the desulfurization tower 3 and the inlet of the calcination device 9. The roasting flue gas after denitration enters the desulfurization tower 3 through a pipeline for dry desulfurization, and then enters the dust collector 4 for physical filtration. The dust collector 4 is generally a bag filter. The temperature of the roasting flue gas coming out of the flue gas outlet of the roasting furnace 1 is 120-180°C. The roasting flue gas enters the desulfurization tower 3 from the flue gas inlet at the bottom of the desulfurization tower 3. The high-temperature roasting flue gas is fully premixed with the desulfurizer and the circulating desulfurization ash for preliminary desulfurization, and reacts with HCl and HF. The desulfurization tower 3 has a circulating fluidized bed. The roasting flue gas is accelerated through the venturi tube at the bottom of the desulfurization tower 3 and enters the circulating fluidized bed. The material fully contacts and reacts with sulfur dioxide in the circulating fluidized bed to produce by-products such as calcium sulfate, calcium chloride, and calcium fluoride. The desulfurization by-products are discharged from the dust outlet of the dust collector 4. The desulfurization by-products contain asphalt and organic matter, which are easy to cause secondary pollution. In order to facilitate the collection and treatment of desulfurization by-products, a tee is connected to the dust outlet of the dust collector 4. One branch of the tee is connected to the desulfurization tower 3 to realize material circulation, and the other branch of the tee is connected to the desulfurization ash bin 8. The outlet of the desulfurization ash bin 8 is connected to the calcination device 9 through a pipeline. The calcination device 9 performs harmless treatment on the hazardous waste in the desulfurization by-products and converts the hazardous waste into general solid waste. For example, the calcination device 9 is a rotary kiln or an incinerator.

[0021] The flue gas outlet of the dust collector 4 is connected to the regenerative catalytic combustion device 5 through a pipeline, and the flue gas outlet of the regenerative catalytic combustion device 5 is connected to the chimney 7 through a pipeline. The regenerative catalytic combustion device 5 is used to treat asphalt smoke and volatile organic compounds (VOCs) in the roasting flue gas. The temperature of the roasting flue gas after desulfurization is relatively high, generally above 80°C. The traditional method uses activated carbon adsorption, and the roasting flue gas needs to be cooled to below 60°C to meet the effective temperature requirements for activated carbon adsorption. In order to avoid the need to cool the roasting flue gas before it can meet the requirements of the effective temperature range of activated carbon adsorption, the adsorption bed of the regenerative catalytic combustion device 5 is a zeolite molecular sieve. The adsorption temperature of the zeolite molecular sieve is lower than 150°C, and the roasting flue gas does not need to be cooled. An induced draft fan 6 is provided on the pipeline between the heat storage catalytic combustion device 5 and the chimney 7. There is generally one induced draft fan 6. In order to ensure the smoothness of the pipeline between the heat storage catalytic combustion device 5 and the chimney 7, two induced draft fans 6 are provided on the pipeline between the heat storage catalytic combustion device 5 and the chimney 7. The two induced draft fans 6 are arranged in parallel. The two induced draft fans 6 can be used one in use and the other in reserve, or they can operate at the same time.

Claims

1. Ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas, characterized by: The invention comprises a non-catalytic reduction denitration device, a desulfurization tower (3), a dust collector (4), a regenerative catalytic combustion device (5) and an incinerator. The non-catalytic reduction denitration device comprises a roasting furnace (1) and an injector (2) for injecting a denitrifying agent into the roasting furnace (1). The flue gas outlet of the roasting furnace (1) is connected to the flue gas inlet at the bottom of the desulfurization tower (3) through a pipeline. The desulfurization tower (3) is provided with a desulfurizing agent supplier (31). The flue gas outlet at the top of the desulfurization tower (3) is connected to the flue gas inlet at the bottom of the desulfurization tower (3) through a pipeline. The dust collector (4) is connected to the dust collector (4), the flue gas outlet of the dust collector (4) is connected to the regenerative catalytic combustion device (5) through a pipeline, the flue gas outlet of the regenerative catalytic combustion device (5) is connected to the chimney (7) through a pipeline, and an induced draft fan (6) is also provided on the pipeline between the regenerative catalytic combustion device (5) and the chimney (7); the dust outlet of the dust collector (4) is connected to a tee, and the two branches of the tee are respectively connected to the dust inlet of the desulfurization tower (3) and the inlet of the calcining device (9).

2. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: The burner in the roasting furnace (1) is a low-nitrogen burner.

3. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: The ejector (2) has a compressed gas connector and is also connected to a dry powder denitrification agent silo.

4. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: The dust collector (4) is a bag dust collector.

5. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: A branch pipe of the three-way pipe at the dust outlet of the dust collector (4) is connected to the inlet of the desulfurization ash bin (8), and the outlet of the desulfurization ash bin (8) is connected to the calcining device (9) through a pipeline.

6. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: The calcining device (9) is a rotary kiln or an incinerator.

7. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: The adsorption bed of the regenerative catalytic combustion device (5) is a zeolite molecular sieve.

8. The ultra-low emission purification equipment for electrolytic aluminum carbon anode baking flue gas according to claim 1, characterized in that: Two induced draft fans (6) are also provided on the pipeline between the regenerative catalytic combustion device (5) and the chimney (7), and the two induced draft fans (6) are arranged in parallel.

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