Limestone is widely used as a sorbent in fluidized bed combustors. The study of limestone attrition characteristics is significant for mass balance and desulfurization efficiency. The present study investigates the sulfation and attrition behavior of limestone in a bubbling fluidized bed reactor. The product distribution and development of the product layer are analyzed by scanning electron microscopy. The experimental results show the attrition rate dropped dramatically at the initial kinetic-controlled regime of the sulfation reaction. The observations show that the distribution of the product is not uniform but primarily concentrated on the external surface of the particle. Meanwhile, the thickness of the product layer at the initial stage of the sulfation reaction reaches 0.7 μm, which is larger than that predicted by previous investigators, and it results in a dramatic decrease in the attrition rate. As sulfation continues, the thickness of the product layer increases and reaches 1.6 μm at the diffusion-controlled regime of the reaction, whereas the attrition rate decays to a steady state. A random pore model is also used to analyze the development of the product layer thickness by counting in the whole reaction surface, but the results show a much smaller value as a result of the lack of consideration of the unreacted core, which verifies the early pore blockage in the initial stage observed in the present study.

中文翻译：

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流化床硫酸化过程中石灰石的磨损和产物层的形成

石灰石被广泛用作流化床燃烧室的吸附剂。石灰石磨耗特性的研究对于质量平衡和脱硫效率具有重要意义。本研究研究了鼓泡流化床反应器中石灰石的硫酸盐化和磨损行为。通过扫描电子显微镜分析产物层的产物分布和显影。实验结果表明，在硫酸盐化反应的初始动力学控制条件下，磨损率急剧下降。观察结果表明产物的分布不均匀，而是主要集中在颗粒的外表面上。同时，硫酸化反应初期的产物层厚度达到0.7μm，比以前的研究者预测的要大，导致损耗率急剧下降。随着硫酸化的持续进行，产物层的厚度增加，并在反应的扩散控制下达到1.6μm，而损耗速率则下降到稳态。还使用随机孔隙模型通过计算整个反应表面来分析产物层厚度的变化，但由于未考虑未反应的核，因此结果显示出较小的值，这可以验证早期孔隙在本研究中观察到的初期阻塞。