Deep purification device and method of electrolytic aluminum exhaust gas

Abstract

The invention discloses a deep purification device and method of electrolytic aluminum exhaust gas. An electrolytic aluminum purification tower is provided with a gypsum slurry circulating region, aninlet flue, a spray layer of the purification tower, a first demister of the purification tower, a liquid accumulation layer of the purification tower, a condensation spray layer of the purification tower, a second demister of the purification tower and a purification tower outlet from bottom to top; the gypsum slurry circulating region is communicated with the spray layer of the purification tower through a purification tower circulating pump; the outlet end of the liquid accumulation layer of the purification tower is communicated with the gypsum slurry circulating region and a limestone slurry circulating tank; the limestone slurry circulating tank is communicated with the condensation spray layer of the purification tower through a circulating cooling tower; the limestone slurry circulating tank and the gypsum slurry circulating region are communicated with a limestone slurry source; and the gypsum slurry circulating region is communicated with a gypsum slurry treatment system. Byfull use of a limestone slurry preparation system in a gas desulfurization system of an original power plant and an auxiliary system of a byproduct treatment system, the deep purification device adopts two-stage wet washing process to perform low-cost deep purification on the electrolytic aluminum exhaust gas purified by a dry method.

Description

technical field [0001] The invention belongs to the technical field of resources and environmental protection, and in particular relates to a deep purification device and method for electrolytic aluminum flue gas. Background technique [0002] During the production of electrolytic aluminum, the flue gas produced contains a large amount of HF and SO 2 , particulate matter and other pollutants, direct discharge will seriously endanger human health and plant growth, so the electrolytic aluminum flue gas must be purified. The electrolytic aluminum flue gas purification method is divided into wet purification and dry purification. The wet purification system is suitable for soluble gases such as SO 2 The capture efficiency of gaseous pollutants such as HF and HF is relatively high, but the purification efficiency is low due to the unsatisfactory gas-liquid separation, the removal efficiency of fine particles is not high, the water consumption is large, the equipment is severely ...

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Problems solved by technology

[0003] With the promulgation of the new national standard "Emission Standard of Pollutants for the Aluminum Industry" (GB25465-2010) and its amendments, the emission requirements for electrolytic aluminum flue gas pollutants (sulfur dioxide, particulate matter and fluoride) have been greatly improved. At the same time, with the completion of ultra-low emission transformation of coal-fired flue gas in the power industry, it will become an inevitable trend to achieve ultra-low emission of electrolytic aluminum flue gas. It is difficult to further improve the treatment efficiency of electrolytic aluminum flue gas treatment process

[0004] For the existing dry adsorption electrolytic aluminum flue gas emission is large, gaseous pollutants (HF, SO 2 ) characteristics of low base concentration and small particle size. At present, the more common electrolytic aluminum flue gas deep purification process adopts a whole set of wet treatment system after the electrolytic aluminum flue gas dry treatment device to realize the electrolytic aluminum flue gas purification process. Deep purification, complex process system, high investment and operation costs, and difficult to implement due to site constraints

Patent CN105603459A discloses a rare earth electrolytic aluminum flue gas purification system and method, using the first stage of dry adsorption to remove fluorine and the second stage of wet desulfurization. The desulfurizers are NaOH, Na 2 CO 3 , Ca(OH) 2 , ammonia water, etc., not only the system is complicated, it is difficult to collect the ultrafine dust after the dry process is not high, but also there are secondary pollutions such as difficult wastewater treatment; patent CN102228775A discloses an electrolytic aluminum desulfurization and defluorination integrated method, using Ammonia water washes, desulfurizes and defluorinates the tail gas of electrolytic aluminum, and performs defluorination in the solution to realize fluorine recovery. The modification process system is complicated, and it is not suitable for modification on existing dry purification devices, and there is secondary pollution caused by ammonia escape

Patent CN106334442A discloses a liquid-phase desulfurization device and method for electrolytic aluminum flue gas. The alkaline absorption liquid is atomized in the flue for purification, and the purified absorption liquid is regenerated and reused. During the atomization process, the fog Liquid droplets are easy to adhere to the flue to avoid fouling and block the flue, resulting in unstable operation of the system and low purification efficiency for electrolytic aluminum flue gas

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