Although it has entered the 21st century, China's energy structure is still dominated by fossil energy. Coal and oil are still in the forefront for a long time. Coal accounts for about 70% of China's total primary energy consumption. The pollution of SO2 and nitrogen oxides caused by coal is the main source of pollution in the urban atmosphere of China. At present, the control of various pollutants is generally carried out by separate removal methods. The sulfuric acid equipment will cause the complexity of the flue gas purification system and the improvement of the treatment cost, and because the system is too complicated, the cooperation between them will be more difficult. This results in a reduction in reliability.
Solid phase absorption/regeneration flue gas desulfurization and denitration technology
The solid phase absorption/regeneration flue gas desulfurization and denitration process uses a solid absorbent or a catalyst to absorb or react with SO2 and nitrogen oxides in the flue gas, and then the SO2 and nitrogen oxides are released from the absorbent in the regenerator. The absorbent can be recycled back to the absorber for recycling; the recovered SO2 can be further processed to obtain by-products such as elemental sulfur or acid; the nitrogen oxides are decomposed into nitrogen and water by spraying ammonia or recycling to the boiler. The absorbents commonly used in the process are activated carbon, copper oxide, molecular sieves, silica gel, etc. The bed of the absorption equipment used has a fixed bed and a moving bed, and the absorption process varies depending on the manner and purpose of the absorbent regeneration.
Gas/solid catalytic simultaneous flue gas desulfurization and denitration technology
This type of process uses a catalyst to reduce the activation energy of the reaction and promote the removal of SO2 and nitrogen oxides. The removal efficiency depends on the combination of the catalytic reaction and the catalyst; and it has higher nitrogen oxide removal efficiency than the conventional SCR process. . Elemental sulfur is recovered as a by-product and no waste water is produced.
Absorbent injection and flue gas desulfurization and denitration technology
Dry powder such as alkali or urea is sprayed into a furnace, flue or spray dry scrubber to simultaneously remove SO2 and nitrogen oxides under certain conditions. These processes can significantly remove nitrogen oxides, and the denitration rate mainly depends on the ratio of SO2 and nitrogen oxides in the flue gas, the reaction temperature, the particle size of the absorbent, and the residence time. An important feature of this process is the presence of a temperature window in which the addition of an alkaline chemistry allows simultaneous removal of SO2 and nitrogen oxides.