Comprehensive treatment method for carrying out desulfurization, denitration, mercury removal and recycling on flue gas of boiler

Abstract

The invention discloses a comprehensive treatment method for carrying out desulfurization, denitration, mercury removal and recycling on the flue gas of a boiler. Sodium hypochlorite which is low in price serves as an oxidation absorbent for purifying flue gas pollutants; SO2, NOx and Hg in the flue gas are oxidized by virtue of a wet oxidization process; oxidation products and part of CO2 in the flue gas are converted into ammonium bicarbonate, ammonium sulfate, ammonium nitrate and mercuric sulfide products with certain economical values; a reduction product of the sodium hypochlorite, namely sodium chloride, is reused as a production raw material of the sodium hypochlorite, and the method is a green process for purification treatment on the flue gas of the boiler. The removal rate of SO2 in the flue gas treated by virtue of the method exceeds 99 percent, the removal rate of NOx exceeds 90 percent, the removal rate of Hg exceeds 95 percent, and the obtained products such as ammonium bicarbonate, ammonium sulfate, ammonium nitrate and HgS are industrial first-grade products, so that recycling is realized.

Description

technical field [0001] The invention belongs to boiler flue gas treatment technology, in particular to a comprehensive treatment method for boiler flue gas desulfurization, denitrification, mercury removal and resource utilization. Background technique [0002] As the consumption of human energy resources continues to increase, the pressure on air pollution prevention and control continues to increase. Coal is still the fuel of choice for power generation due to its abundance and low price. It is therefore important to use this energy in a way that protects human health and ecosystems. If the combustion of coal can meet the current and future increasingly stringent environmental regulations, on the one hand, it is necessary to develop new and more economical clean coal manufacturing technologies, and on the other hand, it is also necessary to develop efficient air pollution control technologies. [0003] The research on flue gas purification first began in 1927. In order t...

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Problems solved by technology

For example: CN103406020 discloses an additive for flue gas desulfurization and denitrification and a method for flue gas desulfurization and denitrification. It uses calcium-based absorption and tetravalent cerium compounds as additives. Although its decontamination efficiency is high, it is easy to block equipment and cause secondary pollution. Secondary pollution; CN1843574 discloses a liquid-phase desulfurization and denitrification purification method and device. The oxidant sodium chlorite is used in combination with additives to oxidize oxides such as S and N and absorb them into salt with ammonia water. The desulfurization and denitrification efficiency is high, and at the same time The product is recycled, but the oxidant consumption is large and the cost is too high; CN102258936 discloses a device and method for mercury recovery in multi-pollutant control technology, which can efficiently remove mercury on the basis of desulfurization and denitrification pretreatment, but the process is cumbersome. High operating costs; CN102658021 discloses an advanced oxidation catalytic desulfurization and denitration integrated process and device, which can obtain resource-based products while decontaminating, but the process is cumbersome and the operation is complicated; CN103041698 discloses a flue gas electrocatalysis-adsorption desulfurization and denitrification The dust removal and heavy metal integrated device combines the adsorbent with the electrocatalytic process, and the decontamination efficiency is high, but at the same time the operating cost is too high; CN103657368 discloses a dry flue gas purification method and device for simultaneous desulfurization, denitrification and mercury removal, Mainly using adsorbents for adsorption, the process is simple, but the cost is high, and it is easy to cause secondary pollution; CN103505997 discloses a method for efficient and collaborative purification of multi-pollutants in flue gas and its application. However, the oxidizing agent is too expensive; CN103585869 discloses a flue gas purification method in which the alkali absorbing liquid can be recycled. After ozone oxidizes the pollutants, it is absorbed by alkali liquid. It is a recycling process without secondary pollution, but the decontamination efficiency needs to be improved; CN101879404 discloses a resource-based flue gas desulfurization and denitrification method. After desulfurization, ozone oxidation and denitrification are used, and finally unified crystallization treatment. This method introduces too many impurity ions, and the purity of resource-based products is difficult to guarantee

[0006] The flue gas purification process mainly has five evaluation indicators (pollution removal rate, liquid-gas ratio, resistance loss rate, post-treatment and cost), these indicators are mutually restricted, however, most of the existing technologies have resistance loss, post-treatment and cost the bottleneck

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