高硫低温高灰烟气环境中SO3的行为研究

在高硫煤机组上抽取烟气搭建了低低温省煤器试验台，并在高硫低温高灰烟气环境下进行了SO₃协同脱除试验研究。试验结果表明：SO₃与SO₂浓度之比约为0.97%；高硫煤低低温省煤器出口SO₃浓度在150~120 ℃随着烟温的降低下降明显。烟温在120 ℃以下时，SO₃浓度随温度的降低变化不明显，且基本处于15 mg/m³以下。烟温在100 ℃以下时，SO₃浓度基本稳定在10 mg/m³左右；烟温降低至100 ℃左右时SO₃的脱除率为84.3%~88.8%；实测SO₃浓度与各个酸露点公式的吻合度均不好，烟温150 ℃以上时，实测数据明显低于计算值，烟温低于115 ℃时，实测数明显高于计算值；高硫煤低温烟气中SO₃浓度的变化受到烟温及飞灰的影响，通过试验研究得出经验公式可以预测烟气中的SO₃浓度。

Study on the Behavior of Sulphur Trioxide in the High-Sulphur Low-Temperature and High-Ash Flue Gas Environment

A low-low temperature economizer test-bed is set up in a generation unit burning high-sulphur coal, and the SO₃ co-removal experiment is carried out in the high-sulfur, low-temperature and high-ash flue gas environment. The results show that the ratio of SO₃ to SO₂ concentrations is about 0.97%, and the SO₃ concentration at the outlet of the low-low temperature economizer drops significantly when the flue gas temperature falls into the range of 150~120℃. By contrast, when the temperature is below 120℃, no significant change of SO₃ concentration is seen with the temperature decrease, which can be kept below 15 mg/m³. While with the temperature of flue gas below 100℃, the SO₃ concentration is basically stabilized at about 10 mg/m³. Especially when the temperature of flue gas decreases to around 100℃, the removal rate of SO₃ is 84.3%~88.8%. Moreover, the measured SO₃ concentrations do not match well with calculated values from the formulas of acid dew point. When the temperature of flue gas is above 150℃, the measured data is apparently lower than the calculated value, while with the temperature below 115℃, the measured value is apparently higher than the calculated value. The change of SO₃ concentration in the low temperature flue gas of high sulphur coal is subject to the flue gas temperature and the fly ash. The empirical formula obtained through this experimental study can effectively forecast the SO₃ concentrations in flue gas.