Abstract: O₂/CO₂ combustion is one of the processes to remove SO₂ from pulverized-coal fired boiler.In this paper, SO₂ emission and removal in O₂/CO₂ combustion were investigated in a fixed bed reactor and a drop tube reactor. The results indicated that the amount of SO₂ emission was much less than conventional air combustion due to the presence of both homogeneous desulphurization and heterogeneous desulphurization in O2/CO2 combustion.Experimental study also suggested that the change of flue gas composition led to the difference of sulphur oxidation degree and the sulphur in coal could be released in different speciations and SO₂ is only one of them.In O₂/CO₂ atmosphere, the desulphurization agent in coal itself showed different desulphurization behaviour comparing with that in air combustion; the desulphurization agent had an optimized microstructure which was beneficial not only for the improvement of the desulphurization efficiency but also for the adsorption of sulphur in the bottom ash.The kinetics calculation results also verified the above mechanism.

Key words: 二氧化碳, 二氧化硫, 燃煤, 脱硫机理, 动力学计算

摘要： 对O₂/CO₂燃烧方式下SO₂的脱除机理进行了研究.静态实验和动态实验结果表明这种新型燃烧方式有利于降低SO₂的排放，SO₂脱除存在均相脱硫和多相脱硫的协同作用;新型燃烧方式下高CO₂浓度导致燃烧气氛中化学成分不同于传统的空气气氛，SO₂与燃烧气氛中存在的其他组分反应，生成硫的不同形态产物，SO₂只是其中的一种产物形态，导致SO₂总量排放减少;同时 O₂/CO₂燃烧气氛使燃煤中硫的氧化程度减弱;燃煤中本身所含脱硫剂存在优化的微观结构，该种结构有利于脱硫和对底灰中硫的吸附，也导致SO₂的排放量降低;CHEMKIN动力学计算结果进一步表征了以上机理.

关键词: 二氧化碳, 二氧化硫, 燃煤, 脱硫机理, 动力学计算