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Casting desulfurization treatment
- Jan 09, 2018 -

The dust removal fly ash desulfurization process using dual-alkali flue gas desulfurization process, the desulfurization reaction speed, high desulfurization efficiency. The dual-alkali flue gas desulfurization process is a modification of the limestone (lime) / gypsum washing process, overcoming the disadvantages of overcoming limestone / lime fouling and increasing the SO2 removal rate. Therefore, the program uses "double-alkali method" process. Double alkali method is more important wet process, with high efficiency of desulfurization and dust removal, less investment, small footprint, low operating costs, etc., is very suitable for China's national conditions. Desulfurization is the use of sulfur dioxide characteristics, that is, acidity, solubility, oxidation, reduction. The sulfur dioxide soluble in water and alkali reaction rate quickly without additional consideration. Under normal circumstances, when the cupola produced flue gas discharged into the desulfurizer, spray a certain amount of lye, lye quality better atomization, desulfurization efficiency. The desulfurization dust collector unique design enables high-speed movement of the stream of alkali for intense stirring, resulting in eddy circulation, repeated atomization, the lye 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 and contact area, so as to achieve the desired desulfurization effect. When alkaline gas is used to wash SO2-containing gas, first, sulfur dioxide reacts with water to form sulfurous acid, and part of sulfurous acid is hydrolyzed to form H-, HSO3- and a small amount of SO32- ions. At the same time in the water

Alkali is dissociated into Na + and OH- ions. The generation of OH- ions reduces the H + ions due to the following reaction: SO2

H2SO3 H ++ As a result of the reduction of HSO3-OH- + H + H2O H +, the amount of HSO3- and SO32- ions is increased so that the amount of undissociated sulfite and physically dissolved SO2 in the solution is decreased and SO2 is continuously absorbed from the gas. At the beginning of excess alkali, SO2 reacts with alkali to produce sodium salt of sodium sulfite (Na2SO3). 2NaOH + SO2 Na2SO3 + H2O Until the base is exhausted and continuing to absorb SO2 from the flue gas, acidic sodium bisulfite (NaHSO3) is generated. Na2SO3 + SO2 + H2O 2NaHSO3 Sodium bisulfite reacts with alkali to regenerate sodium salt of sodium sulfite. NaHSO3 + NaOH Na2SO3 + H2O During operation, inevitable side reactions occur, ie, a small amount of sodium sulfite is oxidized to sodium sulfate (Na2SO4). 2Na2SO3 + O2 2Na2SO4 After adding Ca (OH) 2 into the sedimentation tank, NaOH and gypsum can be regenerated into Na2SO3 + Ca (OH) 2 CaSO3 + 2NaOH Na2SO4 + Ca (OH) 2 CaSO4 + 2NaOH The oxidation rate of sodium sulfite is related to the oxygen content in the flue gas, the types of impurities and circulating fluid, the level of PH value, and so on. System in normal operation, desulfurization operation is in the absorption - regeneration cycle, we can see that the circulating solution is Na2SO4 --- Na2SO3 --- NaHSO3 solution system, the concentration of Na2SO3 and NaHSO3 solution and the ratio is Factors affecting the absorption rate of the key factors.