富氧燃煤锅炉再循环方式对烟气酸露点的影响

Effect of Recirculation Mode on Acid Dew Point of Flue Gas in an Oxy-fuel Combustion Boiler

以某600MW富氧燃煤锅炉为例,对其在3种不同再循环方式下烟气中H2O和SO2体积分数的变化进行了计算与分析,预测了烟气酸露点,并分析了再循环方式对尾部受热面低温腐蚀的影响.结果表明:富氧燃烧下烟气的酸露点比空气状况下高15K左右;再循环方式中脱硫脱水处理过程对烟气中H2O和SO2体积分数影响明显;3种再循环方式下烟气酸露点最大差值可高达11K;烟气酸露点随一次循环烟气比的增加呈下降趋势.

Taking a 600 MW oxy-fuel combustion boiler as an example, variation laws of H2O and SO2 volume fractions in the flue gas were studied under three different recirculation modes, during which a prediction was made to the acid dew point of flue gas, while an analysis performed to the effect of recirculation mode on the low-temperature corrosion of its rear heating surfaces. Results show that the acid dew point of flue gas in oxy-fuel atmosphere is 15 K higher than that in air atmosphere; the H2O and SO2 volume fractions are sensitive to the desulfurization and dehydration process during recirculation period; great difference of acid dew point exists among three recirculation modes, and the maximum difference is high up to 11 K. At the same time, the acid dew point of flue gas decreases with the increase of primary flue gas recirculation ratio.