与袋式除尘器配套的半干法烟气脱硫技术及应用

Semi-dry SGD Technology for Bag-type Dust Collectors and Its Application

循环流化床半干法烟气脱硫除尘一体化工艺(DSDFP)是对半干法脱硫工艺的改进。该工艺的特点是在脱硫塔的前后分别设置一台电场静电除尘器和一台低压脉冲袋式除尘器,电场静电除尘器对烟气进行预除尘,袋式除尘器对脱硫塔出口的高含尘烟气进行除尘。银川热电厂150t/h燃煤锅炉应用了DSDFP系统并进行了运行试验。运行试验结果表明,当进料钙硫比(Ca/S)为1.3、近绝热饱和温度(ΔT)为15℃时,系统的脱硫效率可达85%,烟尘排放浓度小于50mg/m3,满足目前的环保要求。针对DSDFP系统在经过一段时间运行后出现的布袋除尘器压差增大、锅炉负压不稳定、脱硫塔壁面结垢、塔内喷嘴堵塞等问题,经分析采用控制喷水量、优化水喷嘴布置、严格控制雾化角和喷射距离、在脱硫塔内采用双流体喷嘴、合理设计塔内烟气流场等措施进行解决。

The integrated semi-dry stack gas desulfurization and dust removal technology for circulating fluid beds （shorthanded DSDFP） is an evolution of traditional semi-dry desulfurization technology.In this technology, an electrostatic precipitator and a low-voltage impulse bag-type dust collector are respectively installed at the front and back of the desulfurizing tower.The electrostatic precipitator is used for pre-removal of dust in the stack gas and the bag-type dust collector is used to remove dust for the stack gas with high contents of dust at the outlet of the desulfurizing tower.The Yichuan Steam-Electric Plant introduced the DSDFP system in its 150t/h coal-fired boiler and tested the system in a trial operation of the unit.The testing results show that when the Ca/S ratio of the input material is 1.3 and the near-adiabatic saturated temperature AT is 15℃ ,85% of sulfur in the system can be removed and the concentration of dust and fume emitted is less than 50mg/m^3,which meet the current environmental requirements.With respect to the problems detected in the DSDFP system after a period of operation ,such as the buildup of pressure differential in the bag-type dust collector,unstable negative pressure of the boiler,scale buildup on the wall of the desulfurizing tower and the plugging of the nozzle in the desulfurizing tower,technicians have come up with a series of countermeasures including controlling the spraying rate of water,optimizing the positions of water nozzles, strictly controlling the spray angle and spraying distance ,using twin-fluid nozzles in the desulfurizing tower and optimizing the design of flow field of the stack gas in the desulfurizing tower.