Operation Optimization Of The Limestone/gypsum Wet Flue Gas Desulphurization System And Its Influence To Boiler

The sulfur dioxide (SO₂) emission is one of the main air pollution problems right now. In China, the discharge of SO₂ was 23,700,000 tons in 1995, while in 2005, the amount of SO₂ reached 25,490,000 tons, becoming the greatest nation of discharge in the world. Coal-fired power plants contributes the main SO₂ discharge source, which could occupy 40% of the total SO₂ emissions in whole China, therefore, reducing the SO₂ emissions in the coal-fired power plants becomes the key factor to control the total quantity of SO₂. In this paper, based on the introduction of the current discharging situation and endanger,SO₂ discharging standard and flue gas desulphurization technology in power plants, the limestone/gypsum wet flue gas desulphurization system which was used widespread in many power plants due to its higher desulphurization rate was introduced, besides, the chemistry mechanism, technical process, equipment and start-up and shutdown of the system were elaborated in detail. Through the field operation of FGD system in Banshan power plant in Hangzhou, many measures which could insure the economical operation of the FGD system were proposed in this paper, including the reasonable controlling of pH values of absorber and gypsum slurry density, the optimization of operating of scrubber recirculation pump and oxidation air blower, strictly controlling of flue gas dust content, increasing the waste water withdrawal and the optimization of each system controlling and so on. FGD system and boiler influence each other in the process of start-up and shutdown of the system and the cutting over from the bypass and the main road, because of the differences between the two gas roads, the boiler burner negative pressure could be influenced obviously. The paper analyzed the influence of negative pressure in FGD operation particularly, and put forward a series of proposals for FGD and boiler operation.