Analysis of the scale characteristics in salt sludge wet FGD system

Abstract：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.