Effect of rapid water-cooling process on desulfurization performance of CFB bottom ash

doi:10.11949/j.issn.0438-1157.20160227

Abstract

Abstract:

A rapid water-cooling process to desulfurize high temperature CFB bottom ash was designed for the improvement of poor ash utilization. Apparatus and methods for bench-scale rapid water-cooling and desulfurizing study were established and CFB ashes with and without treatment were characterized for f-CaO content, microscopic structure, and desulfurization efficiency. Through theoretical analysis, a hypothesis, that rapid water-cooling could facilitate destroying shell of CaSO₄ particles, was proposed and validated experimentally. Results of SEM/EDX and TGA analyses on treated and non-treated ashes showed that calcium on particle surface increased evidently and the calcium recycling rate could increase about 30% post water-cooling treatment. The desulfurization efficiency enhanced continuously with increasing temperature of CFB bottom ash before rapid water-cooling. When hot CFB ash entered into water, ash particles could burst and destroy CaSO₄ shell due to strong thermal stress across particle surface. Since higher temperature of CFB ash prior to water-cooling would result in stronger thermal stress, CaSO₄ shell were destroyed more easily and desulfurization efficiency became higher. Thus, the rapid water-cooling process would be a new method for regeneration and reuse of CFB ash by improving desulfurization efficiency, which certainly provided practical guidance for engineering applications.

Key words: circulating fluidized bed, bottom ash, waste treatment, regeneration, desulfurization, rapid water-cooling

摘要：

针对循环流化床（CFB）锅炉底渣综合利用率低的问题提出将高温CFB底渣在水中进行急冷的处理方法，搭建CFB锅炉底渣急冷实验台和脱硫实验台，对急冷前后的底渣进行f-CaO含量分析、微观结构特性和脱硫特性研究，通过理论分析提出了急冷有利于破坏颗粒CaSO₄外壳的理论，并通过实验进行了验证。利用扫描式电子显微镜/射线能谱仪（SEM/EDX）和热重分析仪对急冷前后的底渣进行分析，结果表明急冷后底渣颗粒表面钙含量明显升高，急冷后底渣的钙利用率提高了30%左右，底渣急冷前温度越高，底渣的脱硫效率越高，这说明急冷条件有利于提高CFB锅炉底渣的脱硫效率，为CFB锅炉底渣的再生利用提出了一种新的方法，对于实际的工程应用具有一定的指导意义。

关键词: 循环流化床, 底渣, 废物处理, 再生, 脱硫, 急冷

CLC Number:

X773

LI Hao, CHEN Wufeng, WANG Chang'an, CHE Defu. Effect of rapid water-cooling process on desulfurization performance of CFB bottom ash[J]. CIESC Journal, 2016, 67(9): 3583-3589.

李昊, 陈午凤, 王长安, 车得福. 急冷处理对CFB锅炉底渣脱硫特性的影响[J]. 化工学报, 2016, 67(9): 3583-3589.

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