Applied Basic Study On Semi-Dry Sintering Flue Gas Desulfurization Ash Mixed In Fluidized Bed Furnace For The Preparation Of SO₂

With the improvement of environmental requirements,flue gas desulphurization equipment has been large-scale installated and used in sintering plant,and large amounts of desulfurization ash are produced.A common problem faced in all kinds of desulfurization technology currently is how to deal with desulfurization ash effectively.Reference to domestic and foreign research in semi-dry flue gas desulfurization ash and mature sulfuric acid process,the thesis explores the new ways to produce SO₂ from semi-dry sintering flue gas desulfurization ash mixed in sulfuric acid fluidization furnace,depending on the composition characteristics of semi-dry sintering flue gas desulfurization ash in this paper.Firstly,the thermodynamic analysis showed that CaSO₄·2H₂O and CaSO₄·0.5H2 O are unstable at low temperature which are easy to lose crystal water at 110?.Incompletly reactioned Ca?OH?2 and CaCO₃ in the ash will decompose in the roasting process.The CaSO₃ decomposition is related to pressure,temperature and atmosphere.The lower pressure,higher temperature and the lower oxygen content in the atmosphere are more conducive to CaSO₃ decomposition.The thermal analysis showed that,the initial decomposition temperature of CaSO₃ is about 820? under nitrogen atmosphere;it begans to be oxidized at 460? when oxygen excess in the atmosphere;the CaSO₃ is completely oxidized before it reaches to the decomposition temperature in experimental conditions.The decomposition mechanism functions of calcium sulfite in desulfurization ash are f???=1 and G???=?,activation energy E=258.398 k J/mol,pre-exponential factor ln?A/s-1?=26.113,and the kinetic equation d?/dt=2.19×1011×exp?-3.11×104/T?.Then,in order to simulate decomposition behavior of desulfurization ash injection from the upper furnace,desulfurization ash was roasted in drop-tube furnace,the results showed that low temperature,low oxygen and small ventilation are conducive to desulfurization ash decomposition.Finally,a small fluidized bed furnacewas used to test the reaction behavior of mixture of desulfurization ash,pyrite and ferrous sulfate added in the lower of fluidized bed furnace.The results indicated that the less the amount of desulfurization ash,the higher temperature and the longer reaction time are beneficial to the reactions.The newly formed CaO is active to reabsorb SO₂ when the temperature is 850? and the ventilation is 240mL/min.So the release of SO₂ will be reduced,the solution is increasing ventilation appropriately.