Liquid-phase oxidation multistage absorbed flue gas desulfurization and denitrification technology and device

Abstract

The invention discloses a liquid-phase oxidation multistage absorbed flue gas desulfurization and denitrification technology and a liquid-phase oxidation multistage absorbed flue gas desulfurization and denitrification device, and belongs to the technical field of flue gas treatment. The technology comprises the following steps of: performing pre-desulfurization by contact reaction of flue gas and a desulfurizing agent which absorbs a part of sulfur dioxide in the flue gas to obtain desulfurized slurry; performing liquid-phase oxidation and partial absorption on the pre-desulfurized flue gas, and oxidizing nitric oxide in the flue gas into nitrogen dioxide; and performing contact reaction on the oxidized flue gas and the desulfurized slurry to absorb the nitrogen dioxide and the rest sulfur dioxide in the flue gas. The device comprises a desulfurization and denitrification tower and a tower kettle arranged at the bottom of the desulfurization and denitrification tower, wherein a first spraying layer, a sieve plate layer, a second spraying layer and a third spraying layer are sequentially arranged above the tower kettle from bottom to top; and the sieve plate layer is communicated with the second spraying layer through an oxidant slurry tank positioned outside the desulfurization and denitrification tower, and the first spraying layer and the third spraying layer are communicated with the tower kettle through external circulating pumps respectively. The technology is simple and high in desulfurization and denitrification efficiency during desulfurization and denitrification of the flue gas.

Description

technical field [0001] The invention relates to the technical field of flue gas treatment, in particular to a flue gas desulfurization and denitrification process and device for liquid-phase oxidation multi-stage absorption. Background technique [0002] With the continuous improvement of national environmental protection requirements, the flue gas emission standards are becoming increasingly strict, and the desulfurization and denitrification of flue gas is becoming more and more urgent. The main flue gas desulfurization technologies include lime / limestone-gypsum method, magnesium method, ammonia method and other wet processes and semi-dry and dry desulfurization processes. The denitrification technologies include the following: selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), selective non-catalytic reduction and selective catalytic reduction (SNCR-SCR). However, the step-by-step denitrification and desulfurization process is complex, with va...

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Problems solved by technology

Although this method can also remove sulfur dioxide and nitrogen oxides in the flue gas, it still has the following disadvantages: first, it simply absorbs the flue gas multiple times through ammonia water, and does not take measures to oxidize the flue gas. 95% of the nitrogen oxides in flue gas are nitrogen monoxide, which is relatively difficult to absorb. If it is directly absorbed without oxidation, its denitrification efficiency is bound to be low; second, the by-products of desulfurization and denitrification are mixed together, Recycling is difficult, which will inevitably increase the cost of by-product recycling

This method uses liquid-phase oxidation, which simplifies the process and reduces the cost of denitrification compared to gas-phase oxidation. However, the sulfur dioxide contained in the flue gas will consume part of the oxidant, resulting in waste of oxidant. At the same time, sulfur dioxide is oxidized to sulfur trioxide to form acid In addition, the sulfur dioxide in the flue gas cannot be removed well at the same time, and the corresponding desulfurization process needs to be added

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