The Research On Technical Reform Of Semi-dry Flue Gas Desulphurization In Thermal Power Plant

With the development of the society and the improvement of the living standard, human beings place much more emphasis on environment quality. Acid rain resulted from the emission of SO2 in thermal power plants has already jeopardized human's living environment, thus the revision of Emission standard of air pollutants for thermal power plants, the control of the SO2 emission and the installation of facilities of flue gas desulphurization are demanded by the government. Many domestic thermal power plants have not been equipped efficient flue gas desulphurization devices. Semi-dry flue gas desulphurization technique is a widely used technique for its simple equipment, lower capital and easy disposal of waste product. However the substantial consumption of absorbent in the technique causes the high operating cost, so improving utilization rate of the absorbent and desulphurization efficiency is crucial to reduce the running cost.To improve current semi-dry flue gas desulphurization technique in Huanengjiaxiang thermal power plant and reform the structure of dust catcher for energy conservation, the successful examples of semi-dry circulating fluidized bed-flue gas desulphurization technique at home and abroad are used for reference. The conclusion is as follows,1) Powdered lime and desulphurization ash in fume gas are distributed uniformly due to gaseous fluidization, when the dust outlet and desulphurization ash nozzles are moved down.2) The nozzles of Humidifying water are designed for large flow and are equipped in the bottom of the tower with one layer, that can enhance the fogging effects, evade the presence of desulphurization ash in the bottom of the tower, ensure the running safety of electric dust catcher, solve the problem of nozzles blocking and cut down the volume of service work.3) When air conveyer flume technology is applied in ash circulation system, the conveying ability is increased by 50% or more. The conveying distance of the two lateral flumes can be increased in order to make four desulphurization ash nozzles distributed uniformly around the tower. This technology ensures the distribution uniformity of the ash, and it avoids the increasing ash in circulation system. Applying this technology, ash concentration and bed pressure drop in the tower are higher, which improves desulphurization efficiency and makes humidifying system more stable.4)The increased probability of desulphurization reaction and longer residence time are obtained after technological transformation, besides the reaction temperature of new technology is 3℃～5℃higher than that of the former, when both of their efficiency are the same.5) 50% energy is saved by the technological transformation.The current semi-dry desulphurization technology and the structure of the dust catcher in Huanengjiaxiang thermal power plant are reformed.The application of air conveyer flume technology in desulphurization ash circulation system increases the feeding magnitude of the ash and ensures the stability of the fluidized bed. The outstanding effect of energy conservation is caused by the use of power reducing strike. Therefore this technology has a bright future for application.