Flue gas desulphurization based on limestone-gypsum with a novel wet-type PCF device

摘要

The wet flue gas desulphurization has been the most widely used in the coal-fired power plants because of high SO2 removal efficiency, reliability and low utility consumption. In this paper, laboratory studies on the removal of SO2 from gas mixtures with a novel wet-type PCF device (Chinese LOGO) were reported, CaCO3-in-water suspension used as absorbent. The main work included the influences of some process parameters such as slurry pH, limestone concentration in feed stream, SO2 inlet concentration, liquid-gas ratio and superficial gas velocity. Meanwhile, the desulphurization process in the PCF device was analyzed using the two-film theory of gas-liquid mass-transfer. The results show that the PCF device has low pressure drop, large specific capacity for flue gas treatment, high absorption rate and good dewatering performance. Under moderate conditions, the concentration of SO2 in outlet flue gas can achieve a much lower level than that of permitted. The reasonable operating conditions for the PCF device are as follows: slurry pH value is 5.7 ± 0.1, limestone concentration in feed stream is 13 wt.%, SO2 inlet concentration is less than 4.1 g/m~3, liquid-gas ratio is 8.7-10.4L/m~3 and superficial gas velocity in preliminary treating chamber is 2.0-2.5 m/s (3.4-4.3 m/s in inner cylinder). Furthermore, the results obtained from the two-film theory show that the SO2 removal rate is controlled by the combination of both gas- and liquid-film diffusions in the range of operating conditions tested.