The fly-up desulfurization process by primary dust removal adopts double alkali flue gas desulfurization process, which has fast desulfurization reaction speed and high desulfurization efficiency. The double alkali flue gas desulfurization process is a deformation of the limestone (lime)/gypsum washing method, which overcomes the shortcomings of the limestone/lime method that is easy to scale and improves the SO2 removal rate. Therefore, the "double alkali method" process is selected for this scheme. The double alkali method is an important process in the wet process, which has the characteristics of high desulfurization and dust removal efficiency, low investment, small land occupation and low operating cost, which is very suitable for China's national conditions. Desulfurization is the use of sulfur dioxide characteristics, namely, acidic, solubility, oxidation, reduction. However, the speed of reaction between sulfur dioxide and alkali after dissolving in water is very fast, which does not need to be considered. In general, when the flue gas produced by the cupola is discharged into the desulfurizer and sprayed into a certain amount of lye, the better the atomization quality of the lye, the higher the desulfurization efficiency. The unique design of the desulfurization dust collector can make the high-speed air flow intense stirring of the lye, resulting in vortex circulation, repeated atomization, so that the lye is completely atomized, the droplet size is basically below 0.2mm, to achieve the best atomization quality, liquid mist and SO2 fully stirred together, to achieve the best contact mode and contact area, so as to achieve the ideal desulfurization effect. When the gas containing SO2 is washed with alkaline liquid, firstly, SO2 and water react with each other to form sulfurous acid, and part of the sulfurous acid is hydrolyzed to form H-, HSO3-and a small amount of SO32-ions. At the same time in the water

The base dissociates into Na + and OH-ions. When OH-ions are formed, the H ions are reduced by the following reactions: SO2

The result of the reduction of H2SO3 + H + HSO3- OH- H + H2O + H is an increase in the amount of HSO3-and SO32-ions, thereby reducing the amount of undissociated sulfurous acid and physically dissolved SO2 in the solution, thus continuing to absorb SO2 from the gas. When the base is initially in excess, the SO2 reacts with the base to form the normal salt sodium sulfite (Na2SO3). When 2NaOH SO2 → Na2SO3 H2O continues to absorb SO2 from the flue gas until the alkali is exhausted, the acid salt sodium bisulfite (NaHSO3) is generated. Na2SO3 SO2 H2O → 2NaHSO3 sodium bisulfite reacts with alkali and regenerates sodium sulfite as a normal salt. During the operation of NaHSO3 NaOH → Na2SO3 H2O, a side reaction will inevitably occur, that is, a small amount of sodium sulfite is oxidized to sodium sulfate (Na2SO4). Ca(OH)2 is added when 2Na2SO3 O2 → 2Na2SO4 is sprayed and flows into the sedimentation tank to regenerate precipitates such as NaOH and gypsum. The oxidation rate of Na2SO3 Ca(OH)2 → CaSO3 ↓ 2NaOH Na2SO4 Ca(OH)2 → CaSO4 ↓ 2NaOH sodium sulfite is related to the oxygen content in flue gas, the type of soot impurities, the concentration of circulating liquid, and the PH value. During the normal operation of the system, the desulfurization operation is carried out in the absorption-regeneration cycle, thus it can be seen that the circulating liquid is a solution system composed of Na2SO4 --- Na2SO3 --- NaHSO3, and the concentration and ratio of Na2SO3 and NaHSO3 in the solution are the key factors affecting the absorption rate.