烟气中钾含量对锯屑燃烧过程积灰的影响

Influence of Potassium on Ash Deposition During Sawdust Combustion

基于高温一维下行炉,以锯屑为燃料开展燃烧过程积灰实验研究。通过水洗处理和喷加雾化溶液的方式控制烟气中钾的含量,采用自动控温采样枪收集积灰样品。通过积灰量计算出积灰的采集效率,进而分析烟气中钾浓度与采集效率的相关性。结果显示,烟气中钾含量是影响积灰倾向的关键因素,积灰倾向随烟气中钾浓度的增加显著提高。扫描电子显微镜X射线能谱(scanning electron microcopy,energy-dispersive X-ray,SEM/EDX)微观分析发现,烟气中的钾促进积灰形成的途径主要是:钾与硅铝酸盐结合形成的低熔点化合物促进了飞灰颗粒间的烧结;钾在飞灰表面冷凝增加了飞灰的表面黏性。

The sawdust combustion investigation on ash deposition during was performed in a lab-scale down-fired combustor by using an air-cooled temperature-controlled probe To control the potassium concentration in flue gas, water-washed sawdust was used, and the aqueous solution of potassium acetate was sprayed into the flame zone in order to study the effect of potassium. According to the amount of deposit, the collection efficiency was calculated. The results indicated that potassium concentration in flue gas is a key factor that determines the ash deposition. The higher concentration, the more deposit. The technology of scanning electron microcopy, energy-dispersive X-ray （SEM/EDX） analyses revealed that potassium plays an important role in deposition. The significant increase of deposition tendency can be attributed to the combination of the aluminosilicate with the potassium, which forms the new eutectics with a lower melting temperature. At the same time, the surface growth of potassium on big ash particles surface or the adhesion of submicron potassium oxides to big particles increase their work of adhesion.