First, dust removal

The dust removal, desulfurization and denitrification integrated device firstly passes through the pre-pre-dusting, and the flue gas completes the dust removal purpose in the wet process through the subsequent three-stage water body and spraying.

First, denitrification

The denitration agent FeSO4 dissolves in water and increases the Fe2+ mass fraction in water, which can promote the complexation reaction between NO and Fe2+ in the flue gas. The solubility of NO in the flue gas is very low, but after adding Fe2+ in the water, NO can complex with Fe2+ to form a ferrous nitrosyl complex, which accelerates the absorption rate of NO and increases Its absorption capacity. When the FeSO4 water is in contact with the flue gas, the Fe2+ complex absorbs 90% of the "NO" atoms in the NOx, so that N is reduced to N2 and returned to the atmosphere (others believe that there are still NH3 can be absorbed by desulfurization products, activated cokes, etc. in water. Complexation reaction mechanism: (chemical reaction formula given by Professor Su Yongzhen, a professor of environmental engineering at Northeastern University)

During the denitrification treatment, Fe2+ in the water is oxidized to Fe3+ by NO and residual O2 in the flue gas, while Fe3+ has no affinity with NO, and can not continue denitrification, and the denitrification capacity of the water body will be gradually weakened. In order to maintain the denitrification activity of the water body, a reducing agent, iron filings, is added to the water body.

Third, desulfurization

Flue gas desulfurization is carried out in two steps: pre-desulfurization of the first layer of water bed and enhanced desulfurization of the second layer of water bed.

The main function of the first layer of water bed is dust removal and denitrification. At the same time, the SO2 in the flue gas can be initially cooled, dissolved in water and pre-desulfurized. When the flue gas enters the first large water body water bed, SO2 in the flue gas is absorbed by water to form sulfurous acid (H2SO3). The complex absorption product of NO in the flue gas denitration process - nitrosyl sulfate can react with SO32-/HSO3- formed by SO2 absorption in the solution to form a series of NS compounds, and regenerate and regenerate Fe2+. While Fe2+ is in progress, it can be cured to absorb a part of SO2.

The second layer of water bed is desulfurized by sodium and calcium double alkali process. The main desulfurizers in the water are NaOH and Na2CO3. Flue gas in the second layer of large water body to carry out the "gas surface" and "liquid surface" full impulse desulfurization reaction, in the water bed inlet and outlet with a small power pump to extract its own water body water for interception spray enhanced desulfurization.

The main product of the desulfurization process is Na2SO3, and since its bulk density is higher than that of water, it can be periodically discharged in each cone of the water bed. The effluxed Na2SO3 flows into a single ash pool (lime caustic cistern) outside the machine body, reacts with the alkaline ash in the pool and the normally input quicklime to form a precipitate of CaSO3 and NaOH supernatant.

The regenerated NaOH is returned to the upper large water body water bed to continue desulfurization. The CaSO3 is blended with the ash in the ash pool, and is gradually oxidized due to constant disturbance of the water body when it is regularly grasped by the grab machine, and part of it can be converted into CaSO4. The dust soot and the desulfurization products CaSO3 and CaSO4 which are regularly caught by the grab machine can be recycled.