Design of Flue Gas Purification in Aluminum Electrolytic Plant
Abstract: In order to meet the specifications of environmental protection of the aluminum electrolytic plant and make the quality of the flue gas meet the standards, the flue gas purification of the aluminum electrolytic plant has achieved remarkable results. This paper focuses on the design methods of the process of flue gas purification, the choice of pollution control equipment and the final results that can be achieved.
1. Introduction
The aluminum industry is one of the leading industries in our country, and aluminum electrolysis is a key link in the industry chain. The process of aluminum electrolysis requires a certain amount of power, among which the proportion of aluminum electrolysis is quite large. With the rapid development of the aluminum industry, the scale of aluminum electrolytic plants has been continuously expanded. The by-products of major aluminum electrolytic plants are mainly dissolved gas and flue gas, both of which are hazardous air pollutants. The purification of the flue gas of aluminum electrolysis plant has always been a challenge within the aluminum industry.
In order to meet the standards of environmental protection, aluminum electrolytic plants must take effective measures to reduce the harmful substances discharged in the exhaust gas. This includes purifying the flue gas. The design of flue gas purification process is not only an important part of environmental protection management, but also an important link in the process of energy conversion in aluminum electrolytic plant. In this paper, the design methods of flue gas purification in aluminum electrolytic plant and the selection of pollution control equipment will be introduced.
2. Design of Flue Gas Purification Process
The flue gas purification in aluminum electrolytic plant mainly includes dust removal, desulfurizing, de-dusting and dechlorinating, ammonia stripping and other processes.
Dust removal: dust removal is the first step in the purification of aluminum electrolytic plant flue gas. It helps to reduce the content of large particles of dust and other particles in the flue gas. The dust removal process can be natural sedimentation, electrostatic dust removal, fabric filter dust removal, cyclone dust removal and other processes.
De-sulphurization: the main purpose of desulfurization is to reduce the content of sulfur dioxide. The flue gas is absorbed by reducing the reaction of the desulfurizing agent, so as to achieve the purpose of desulphurization. The main desulfurization methods are spray desulfurization, dry desulfurization and wet desulfurization.
De-dusting and dechlorination: in order to reduce the dust and chlorine content in the flue gas, the aluminum electrolytic plant usually adopts the absorption and reaction method, that is, with the aid of chemical absorbent, the dust and chlorine in the flue gas are absorbed and reacted, and then removed from the flue gas.
Ammonia stripping: ammoniac stripping is mainly used to reduce the content of ammonia in the flue gas. In general, the process of ammonia stripping is to react the ammonia in the flue gas with the aqueous alkali solution, and then extract the ammonia in the reaction solution by vacuum or pressurized evaporation.
3. Selection of Pollution Control Equipment
The main equipment used in the flue gas purification process of aluminum electrolytic plant includes: dust remover, desulfurizer, de-duster, dechlorinator and ammonia stripper. The main specifications and models of the pollution control equipment should be determined according to the flue gas volume and pollutant concentration of the aluminum electrolytic plant.
Dust remover: the dust removal equipment mainly includes: cyclone dust collector, fabric filter, electrostatic precipitator and other types. The choice of dust removal equipment should be based on the size of dust particles, dust content and dust removal efficiency requirements of the flue gas.
Desulfurizer: desulfurization equipment mainly include spray desulfurization, dry desulfurization and wet desulfurization. The choice of desulfurization equipment should be based on the concentration of sulfur dioxide in the flue gas, desulfurization efficiency, desulfurization cost, investment and operating cost.
De-dusting and dechlorination equipment: the main de-dusting and dechlorination equipment are spray de-dusting and dechlorination towers. The choice of equipment should be based on the amount and concentration of dust and chlorine in the flue gas.
Ammonia stripper: the main equipment of ammonia stripping is the scrubber. The selection of scrubber should be based on the amount and concentration of ammonia and the required emission concentration of ammonia.
4. Conclusions
The design of the flue gas purification system in aluminum electrolytic plant should fully consider the pollution control cost and the results that can be achieved. Because of the influence of many factors, the design should be modified several times and then confirming, so as to ensure that the design is correct. Through the design of flue gas purification process and the selection of pollution control equipment, the emission concentration of flue gas pollutants can be controlled to reach the environmental protection standard.
References
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[4] Xiao, Hua. Research on environmental pollution by aluminum electrolysis and measures for environmental protection. Shenzhen University (2018).
