Thermal stability of acidic sulfates in kraft recovery boilers

摘要: Acidic sulfates, such as NaHSO[sub 4] and Na[sub 2]S[sub 2]O[sub 7], are suspected in sticky deposit formation tube corrosion the generating bank economizer regions of kraft recovery boilers. Their stability was examined air, moist conditions, presence 2]CO[sub 3] at various temperatures. The results showed that, melts decomposes to solid 7] water vapor about 180 C. is relatively stable up its melting point 380 Molten partially 2]SO[sub 4], which reacts with remaining form a newly identified compound, 3Na[sub 7][center dot]2Na[sub 4]; this compound 570 Solid complex compounds react rapidly H[sub 2]O 300 C re-form liquid can be corrosive for tubes during boiler operation. These acidic sulfates coexist below their respective points. They hygroscopic, absorbing from air sulfuric acid, may cause wastage outages.