流化床垃圾焚烧过程受热面烧结积灰的生长特性

The characterization of sintering deposit on the heat-transfer surface of CFB municipal solid waste incinerator

使用扫描电子显微镜、能谱、X射线衍射等分析手段,对流化床垃圾焚烧炉过热器的烧结积灰内部各部分的微观结构和成分组成进行研究。结果表明,积灰中富含钙和硫,主要的矿物成分是CaSO4。烧结积灰沿生长方向可分为根部和生长段,根部中元素钙和氯的质量分数高于生长段,而硅和铝的质量分数明显小于生长段,根部内层碱金属钠、钾的质量分数较高,含碳量也很高。积灰根部的结构较生长段致密,密实的根部内层主要是凝结沉积以及亚微小颗粒热迁移共同作用形成的,过渡层和生长段的形成主要是惯性沉积和气固高温反应共同作用下长时间烧结的结果,熔融相和化学反应的共同作用是烧结积灰生成生长的主要动力。

By using scanning electron microscope （SEM）, energy dispersive X-ray analysis （EDX） and X-ray powder diffraction analysis （XRD）, the microstructure, elemental and mineral components of interior parts of sintering deposit from the superheater surface of a field-scale circulated fluidized bed （CFB） municipal solid waste （MSW） incinerator were studied. The results show that the deposit is rich in calcium and sulfur. The main mineral in the deposit is CaSO4. The structure of sintering deposit can be divided into root and growth part. Calcium and chlorine are higher in root than in growth part, while silicon and aluminium are much lower in the root. More alkali metals such as sodium and potassium Moreover, large amount of carbons present in the are found in the inner layer of the root than in outer layers. inner layer. The framework is more compact in root than in growth part. Vapor phase condensation and thermophoresis of submicro-granule are the leading mechanisms of the formation of inner layer of root. Transition layer and growth part are formed mainly by inertial impact of fly ashes and gas-solid chemical reactions as well as high temperature sintering. The co-effect of fusion phase and chemical reactions is the primary growth motivity of the sintering deposit.