燃煤烟气盐泥湿法脱硫系统中垢的特性分析

Analysis of the scale characteristics in salt sludge wet FGD system

针对盐泥湿法烟气脱硫系统中出现的结垢问题,采用XRD、SEM、EDS等对盐泥及垢的特性进行了测试,并对垢的成因进行了分析。结果表明:盐泥颗粒主要以团聚物形态存在,粒径小且对脱硫有利的化合物含量高,非常适合湿法烟气脱硫工艺。烟道垢与塔内垢的表观结构显著不同,与塔内垢相比,烟道垢厚度较小,表面光滑且质地紧密。两者微观结构也有显著差异,烟道垢以菱形结晶体为主,结晶比较完整,晶体间排列紧密;塔内垢以柱状或块状结晶体为主,间杂有较多不规则小晶粒,结晶体大小不一且排列散乱,不规则小晶粒中SiO2含量相对较高。两种垢的主要成分均是CaSO4.2H2O和CaSO4.0.15H2O,形成原因与CaSO4的过饱和析出以及所处位置有关,盐泥自身含有的Si、Mg元素对垢的形成影响很小。

The characteristics of salt sludge and scale and the formation causes of scale were analyzed through XRD,SEM and EDS.The results show that most of salt sludge particles exist as aggregation,the little diameter of particle and the high content of calcic compound means this kind of salt sludge is quite suitable for wet FGD system.The apparent structure and microstructure of scale in flue is different from which in tower.Comparing with the scale in tower,the scale in flue is thinner and has a smoother surface,and the structure is hard-packed.The crystal shape of scale in flue is mainly rhombic,and has a relatively complete,dense and packed microstructure,but the crystal shape of scale in tower is mainly columnar and block,and include more irregular crystalline particles.The crystalline structure is loose,and more SiO2 is contained in irregular crystalline particles.The major constitutes of tow kinds of scale are CaSO4·2H2O and CaSO4·0.15H2O,the formation cause relates to separation of CaSO4 under the condition of supersaturation and formation location of scale.The Si and Mg elements contained by salt sludge itself have little effect on formation of scale.