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Key Technologies of Efficient and Cooperative Treatment of Flue Gas Pollutants in Iron and Steel Industry
Applicating Company
Shandong Guoshun Construction Group Co., Ltd
Technology Name
Key Technologies of Efficient and Cooperative Treatment of Flue Gas Pollutants in Iron and Steel Industry
Technical principle
The flue gas of iron and steel industry contains a large number of conventional pollutants such as NOx, SO2 and particulate matter, as well as unconventional pollutants such as heavy metals. After dust removal, the flue gas reacts with NH3 to generate N2 and H2O under the action of medium and low temperature catalysts, so as to achieve the purpose of denitrification. Then the flue gas enters the desulfurization system, SO2 reacts with limestone gypsum to generate gypsum, so as to achieve the purpose of desulfurization. Finally, the flue gas enters the wet electrostatic precipitator, the removal of particulate matter and particulate heavy metals is realized under the action of electric field.
Denitration reaction principle is as follows:
4NO＋4NH3＋O2→4N2＋6H2O
NO＋NO2＋2NH3→4N2＋6H2O
The desulfurization reaction principle is as follows:
CaCO3+SO2+ 1/2H2O→ CaSO3·1/2H2O+CO2
CaSO3·1/2H2O+SO2+ 1/2H2O→ Ca(HSO3)2
As there is excess oxygen in the flue gas, the following reactions will occur:
2CaSO3·1/2H2O+1/2O2+3H2O→2CaSO4·2H2O
Absorb the slurry to be oxidized by the air blown in, and finally generate gypsum（CaSO4·2H2O）
2CaSO3·1/2H2O+O2+3H2O→2CaSO4·2H2O
Ca(HSO3)2+1/2O2+H2O→CaSO4·2H2O+SO2
Scope of application
This technology is applicable to the main pollution producing processes in steel production. The flue gas pollutant treatment projects of different raw materials/fuel sources (China, Brazil, India, etc.), different flue gas temperatures (sintering: 100-200℃, pelletizing: 120-150℃, coke oven: 160-300℃), different fly ash characteristics (sintering fly ash has high alkali metal content, strong viscosity, high hardness of pellet flue gas fly ash, coke oven flue gas contains high viscosity tar, etc.), different processes (sintering, pelletizing, coking and calcination) and different scales (such as sintering area of 40-660m2) have achieved stable ultra-low emissions.
Process flow and description
The flue gas after dedusting (the sintering flue gas enters the heat exchanger for preheating after flue gas conditioning, and then goes through the hot air furnace or flue heater for supplementary combustion and temperature rise, and then goes through the ammonia injection and hot air mixing device to inject hot air and reducing agent) successively through the medium and low temperature SCR denitration, limestone/lime gypsum desulfurization and wet electrostatic precipitator, to achieve the comprehensive treatment of NOx, SO2, particulate matter, heavy metals and other pollutants, and achieve ultra-low emissions.
Promotion prospects
This set of equipment has reliable quality, stable operation, and high efficiency. The emission of nitrogen oxides, SO2 and fine particulate matter is superior to that of the state. At the same time, it can effectively ensure the energy saving and consumption reduction indicators of equipment operation, and further improve the stability and reliability of products through collaborative removal of multi pollutants and intelligent operation regulation. The promotion and application of this product is in line with the national policy guidance, and has a great significant to the sustainable development of the environmental protection industry and the improvement of the current situation of the iron and steel sintering flue gas pollution, so it has a good market prospect.