升温过程干法半干法脱硫灰中硫酸盐的稳定性研究

Study on the Stability of Sulfate in Desulfurization Residues Produced by Dry and Semi-dry Methods during Heating Process

[目的]研究不同气氛、湿度和温度对脱硫灰中硫酸盐稳定性的影响。[方法]通过改变气氛、脱硫灰湿度、焙烧温度的条件，研究干法和半干法脱硫灰中硫酸盐的稳定性。[结果]在空气条件下，当焙烧温度为450—700℃时，脱硫灰中的CaSO3能迅速氧化成性质稳定的CaSO4；当焙烧温度为750～1050℃时，脱硫灰中的CaSO3能同时发生氧化和分解，部分CaSO3分解为CaO和SO2。在氮气条件下，CaSO3在650℃开始分解。随着脱硫灰湿度的增加，SO2的逸出量越大，CaSO3的分解率越大，同时由CaSO4的分解产生SO2。在800～1050℃，SO2的逸出量随着温度的升高而增加。[结论]450～1050℃，SO2的最大排放浓度为101．4mg／m^3，远远低于国家标准（800mg／m^3）。

[ Objective ] The purpose was to study the effects of different atmosphere, humidity and temperature on stability of sulfite in flue gas desulfurization （FGD） residues made by dry and semi-dry method in the heating process. [ Method] The stability of sulfite in FGD residues produeed by dry and semi-dry methods in the heating process was studied through changing the atmosphere, the humidity of FGD residues and the temperature of calcination. [ Result ] In air, when the temperature of calcination was 450 -700 ℃, CaSO3 in FGD residues was quiekly oxidized into stable Ca.SO, ; when the temperature of caleination was 750 - 1 050 ℃, CaSOa in FGD residues eould oeettr the oxidation and decomposition simultaneously and some CaSO3 was decomposed into CaO and SO2. In N2, CaSO3 could begin to be decomposed at 650℃. With the rising of the humidity of FGD residues, the greater the escaped amount of SO2 was, the bigger the decomposition rate of CaSO3 was and then SO, eould occur from the deeomposition of CaSO4 at same time. In the rang of 800 - 1 050 ℃, with the rising of the temperature, the emission amount of SO2 was increased. [ Conclusion] In the range of 450 - 1 050 ℃, the maximum emission conch, of SO2 by calcining the FGD residues was 101.4 mg/m3, which was far lower than the national standards（800 mg/m3 ）and didn＇t make any damage to the environment when the FGD residues was used again.