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流化床技术在热转化生物质方面具有优势,但生物质流化床锅炉在运行中,经常遇到床料结渣问题。该文用流化床实验装置燃烧麦秸,发现床料发生了严重的团聚结渣,床层流化状态明显恶化。随着运行时间延长,床料颗粒表面富集越来越多的钾。分析表明,渣块中的融化物组成可以用K2O-CaO-SiO2三元系简化,三元系相图可解释融化出现的原因。由于生物质灰熔点低,燃烧的半焦表面变黏,黏结床料颗粒产生结渣。通过与细灰碰撞,床料颗粒表面形成一层均匀的灰层并融化,当灰层足够厚时,黏性力让床料颗粒通过有限的点黏结在一起,形成结渣。
Fluidized bed technology has advantages in thermal conversion of biomass, but the biomass fluidized bed boiler often encounters the problem of bed material slagging during operation. This paper uses a fluidized bed experimental device to burn wheat straw and finds that the bed material has a serious agglomeration and slagging, and the bed fluidization state is obviously deteriorated. As the run time is extended, more and more potassium is enriched on the surface of the bed material particles. The analysis shows that the melt composition in the slag block can be simplified by the K2O-CaO-SiO2 ternary system, and the ternary phase diagram can explain the reason for the melting. Due to the low melting point of biomass ash, the surface of the semi-coke burned becomes sticky, and the agglomerated bed material particles are slagging. By colliding with the fine ash, the bed material particles form a uniform layer of ash on the surface and melts. When the ash layer is thick enough, the viscous force causes the bed material particles to stick together through limited points to form slagging.