添加剂对棉杆抗结渣性能影响

Effects of Additives on Slagging Resistance of Cotton Stalk

生物质资源燃用过程中的结渣、团聚等问题限制了该资源的规模化利用,为减缓棉杆燃烧过程中结渣问题,该文探究棉杆中不同赋存形式的钾对其烧结温度和灰熔融特征温度的影响,研究碳酸钙、磷酸钙、磷酸二氢铵3种添加剂的抗结渣性能,探明3种添加剂抗结渣机制。结果表明:逐级萃取可除去棉杆中绝大部分钾元素,水萃取后棉杆灰熔点显著提高,醋酸铵萃取后灰熔点降低,盐酸萃取对棉杆灰熔点提高不明显。磷酸钙添加剂可将棉杆中钾固定在K-Ca-P三元复盐体系中,并提高其灰熔融特征温度,抗结渣效果好。磷酸二氢铵固钾效果较好,但对棉秆灰熔融特性的改善效果不佳。碳酸钙固钾效果较弱,但可提高棉杆烧结温度及灰熔融特征温度。3种添加剂的抗结渣性能为磷酸钙最优,其次为碳酸钙,磷酸二氢铵最弱。

Alkali slagging and agglomeration during biomass combustion utilization restrict the large-scale utilization of biomass resources.In order to alleviate the problem of biomass slagging,the contents of different forms of the potassium contained in cotton stalk are determined,and the effects of potassium on slagging characteristics of the cotton stalk are investigated.The influences of calcium carbonate,calcium phosphate and ammonium dihydrogen phosphate on the melting characteristics of cotton rod ash are studied,and the anti-slagging mechanisms are explored.The results show that most of potassium can be removed from the cotton stalk by fractional extraction.The melting point of the cotton rod ash can be significantly increased by water extraction,but decreased after ammonium acetate extraction,without obvious effects after hydrochloric acid extraction.Calcium phosphate can fix the potassium in cotton stalk ash in the ternary salt system of K-Ca-P and increase the characteristic temperature of ash melting,which has a good anti-slagging effect.Ammonium dihydrogen phosphate has a good effect on potassium fixation but does not improve the melting characteristics of cotton rod ash.The calcium carbonate shows weak effect on the potassium but increases the sintering temperature and ash melting characteristic temperature of the cotton stalk ash.The slagging resistance of the three additives is calcium phosphate,followed by calcium carbonate;and ammonium dihydrogen phosphate is the weakest.