The flue gas from the exit of heat recovery boiler first passes the flue and enters the semi-dry scrubber. The flue gas distributor at the top of the semi-dry scrubber can induce the flue gas into the scrubber evenly. The semi-dry scrubber is equipped with rotary atomizers. The lime slurry from the lime slurry preparation system is then transferred into the semi-dry scrubber by the transfer pump. The lime slurry and water will pass the high-speed rotating atomizer at the top of the scrubber. The average droplet diameter of lime slurry and water is about 45μm. These droplets can be mixed evenly and intensively with the flue gas in the scrubber. By controlling the distribution of gas, the flow rate of lime slurry and the size of droplets, it can be guaranteed that the droplets are dried before contacting the inner wall of the scrubber. Billions of tiny droplets will make intensive contact with SO2, HCl, HF or other pollutants in the flue gas and thus absorb these pollutants in neutralization reactions. During the deacidification process, the flue gas temperature also drops from about 190~230℃ to about 152℃. Dry products such as fly ash and other reaction products will drop into the bottom part of the semi-dry scrubber and discharge into the fly ash transfer system. The flue gas emitted from the semi-dry scrubber will enter the bag filter for further neutralization. Remaining dust can also be captured.