研究论文
王春波,沈湘林.调质碳酸钙硫化机理的实验研究[J].环境科学学报,2001,21(6):664-668
调质碳酸钙硫化机理的实验研究
- An investigation on mechanisms of modified limestone sulfation
- 基金项目：973国家重点基础研究专项经费资助项目(项目号:G1999022206)
- 作者
- 单位
- 王春波
- 东南大学热能工程研究所,南京 210096
- 沈湘林
- 东南大学热能工程研究所,南京 210096
- 摘要：对经Na2CO3溶液调质后石灰石煅烧、硫化特性进行了研究,发现调质后石灰石比未经调质石灰石具有更快的煅烧分解速率.CO2浓度变化对调质CaO硫化效果的影响程度要比未经调质CaO更为明显.调质CaO比调质前具有更高的最终钙转化率,但脱硫剂微观结构测定表明,调质CaO比表面积和孔隙率均小于同等条件下获得的未经调质CaO比表面积和孔隙率.利用X衍射技术对CaO晶体结构进行了测定,对比晶格畸变度等参数并综合煅烧、硫化及脱硫剂孔特性,提出了调质CaO硫化反应机理为:前期为化学反应控制阶段,后期为离子扩散控制阶段.应用分形理论对CaO分形维数进行了计算,发现随CO2浓度的增加,无论调质与否得到的CaO,分形维数均呈下降趋势.
- Abstract：The sulfation characters of limestone modified by Na2CO3 solution were investigated in this laboratory. The modified limestone decomposed more quickly than nonmodified limestone. It is shown that modified CaO the Ca conversion in modified CaO is nigher than in nonmodified CaO when sulfation reaction completed. It is also found that influence of CO2 concentration on sulfation character of modified CaO is more violently than of nonmodified CaO. Although the surfur capture capability of modified CaO is well excess that of nonmodified CaO, the microstructure measurement shows that specific surface area and porosity of the former are less than that of the latter. A new sulfation mechanism is proposed that the sulfation reaction of modified CaO is divided into two steps,i.e. at initial stage the chemical reaction between CaO and SO2 is rate-limiting step and as reaction continue the rate-limiting step changs to solid-state diffusion through product layer. The crystal structure of CaO was measured by X-ray diffraction(XRD) analysis.The parameters, such as crystallite size, lattice distortion degree, et al. are base of this mechanism. Fractal theory has been applied to the pore structure of CaO, it is found that a certain CaO the sulfation impact getting worse with fractal dimension decreasing.
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