循环流化床（CFB）富氧燃烧技术可同时控制SOx、NOx、CO2排放，是目前最有应用前景的洁净煤燃烧技术之一。但该技术还存在许多关键理论问题亟待解决。其中，CFB富氧燃烧下石灰石硫化反应是直接硫化反应，其形成的硫酸钙产物层具有多孔性，反应物质在多孔性产物层中的扩散机理是最有争议的问题之一。本研究针对石灰石直接硫化反应形成的多孔性产物层中存在的缺陷扩散机制，以宏观试验为基础（TGA动力学+0.8MW级CFB富氧燃烧硫化试验），探讨多个因素（气体组分、温度、石灰石种类等）对石灰石直接硫化反应同时发生作用时的权重关系；从微观特性入手，利用SEM能谱、示踪剂等微观分析手段，通过电导法和辐射法，探讨产物层中缺陷的产生、缺陷扩散的驱动力描述、产物层中封闭孔对缺陷扩散的"阻碍效应"及缺陷扩散系数的求取等关键问题。该项目研究成果将为CFB富氧燃烧过程中采用石灰石控制SOx排放提供重要的理论依据。

Oxy-fuel CFB combustion is one of the most potential technologies for SOx, NOx and CO2 emission control today. However, there are still many problems need to be solved. For example, the sulfation of limestone happened in oxy-fuel CFB belong to direct sulfation, and the CaSO4 is porous. So, how about the diffusion mechanism happened in the CaSO4 porous product layer? Based on the defect diffusion mechanism exited in porous CaSO4 product layer formed by limestone direct sulfation, this proplem hope to be solved in this study. The testing including: TGA for reactioin kinetics and 0.8MW oxy-fuel CFB for polit scale sulfation testing, the aim is to find the weight of gases, temperature, the kinds of limestone, etc, when they play roles together in the limestone direct sulfation. Combined with SEM, tracer element, conductance measurement, etc., the reasons for why pores produced in product layer, how the defect formed and the drive force for void defect move, the "block effect" for defect diffusion by closed pores and the calculation for defect diffusion rate, etc. The results will provide more theories support for the using of limestone as sorbens for control the emission of SOx in oxy-fuel CFB combustioin.