氧化镁烟气脱硫反应特性研究

利用实验室规模的鼓泡式反应装置,对比了碳酸钙、氧化镁和氧化镁/硫酸镁脱硫剂的反应活性,证实脱硫液中高浓度硫酸镁的存在是保证镁法脱硫效率高于钙法的重要因素,并考察了硫酸镁浓度、脱硫剂(氧化镁)浓度、烟气量、SO2浓度和吸收液温度等因素对脱硫效率的影响。结果表明,脱硫反应可以根据pH分为2个不同阶段;反应过程中脱硫效率随着硫酸镁浓度的增加而显著升高;烟气量增加将会导致脱硫效率有所下降;入口SO2浓度升高,脱硫效率下降;氧化镁浓度、温度对脱硫效率影响不显著。结合实验现象进行推断,氧化镁脱硫的反应过程受SO2在气液两相界面的传质扩散和其水解产物在液相的扩散控制。

Study on the characteristics of flue gas desulfurization by magnesium oxide

The reactivity of the calcium carbonate,magnesium oxide and magnesium oxide/magnesium sulfate were compared using laboratory-scale bubbling reactor,and the result confirms that the high concentration of magnesium sulfate in desulfurizing liquid was an important factor for magnesium oxide to gain higher desulfurization efficiency than calcium carbonate.Then the relationships between desulfurization efficiency and several factors were studied,including flow rate of the simulated flue gas,concentration of magnesia absorbent and magnesium sulfate,concentration of sulfur dioxide in the flue gas,and temperature of the absorption liquid etc.The results indicate that the whole desulfurization process can be divided into two parts according to the pH value of absorption liquid.The desulfurization efficiency increased with the increase of concentration of magnesium sulfate;and decreased with the rise of flue gas flow rate or concentration of sulfur dioxide.The temperature and concentration of magnesia absorbent have no obvious effect on the desulfurization efficiency.It can be concluded that magnesium desulfurization process is controlled by the mass transfer of sulfur dioxide at the gas-liquid interface,especially the transfer of its hydrolyzate in liquid film.