Research On The Assisted Desulfurization Technology In 300MW CFB Boiler Burning Coal Gangue

Since July 1st, 2014, the Emission standard of air pollutants for thermal power plants has came into operation, in which, it decline the SO2 emission from 400mg/m3 to 200mg/m3 of thermal power plants, which is a great challenge to the coal-fired power plant.A CFB boiler burning coal gangue of power plant has been using inner-furnace desulfurization, it can guarantee to keep the concentration of SO2 below 400 mg/m3. However, the single inner-furnace desulfurization unable to further make the flue gas SO2 content dropped to below 200 mg/m3, so the power plant began to seek a kind of new desulfurization technology to make up for the inadequacy of the efficiency of inner-furnace desulfurization. After the previous technological verification, site investigation and theoretical calculation, equipment featured in desulphurization within the CFB boiler by sprinkling ammonium hydroxide in the rear smoke channel was relished through independent research and development. Ammonium hydroxide sprinkled to the rear smoke channel directly by this desulphurization system, will react with SO2 and create byproduct which will be caught by the bag-type dust collector and removed out of the flue.After applied to the relevant departments of the test period, adjusted the content of SO2 in flue gas to 1500 mg/m3.Choosing the stable load working condition and adjusting the input limestone amount to increase the SO2 amount in the smoke channel, the writer tested the system and knew the system running characteristic. The ammoniac use ratio is 13.2% after the ammonium hydroxide sprinkled into the channel and the ratio of CaO turn into Ca(OH)2 is about 22% after water involved. The data showed that the real desulphurization rate is 2.02 time of the theory. The biggest amount of ammonium hydroxide flow can be calculated through the acid dew point and it is helpful to set the ammonium hydroxide concentration and flow under different concentration of SO2 condition, which can best achieve the gas emission standard. Also, it provided a new reference to desulphurization of CFB boilers.