Enhancement of the sulfur capture capacity of limestones by the addition of Na2CO3 and NaCl.
Enhancement of the sulfur capture capacity of limestones by the addition of Na2CO3 and NaCl.
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DOI：
10.1021/es0108279
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发表时间：
2001-11
影响因子：
11.4
通讯作者：
K. Laursen;J. Grace;C. J. Lim
中科院分区：
文献类型：
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作者：
K. Laursen;J. Grace;C. J. Lim
通过固定床焙烧和硫酸盐化实验，评价了Na2CO3和氯化钠对三种石灰岩固硫能力的影响。测试的石灰岩表现出三种不同的硫化形态：未反应核、网状和均匀硫化。用水或粉末Na2CO3处理显著提高了两种结石的钙利用率，这两种结石通常以未反应的核型(20%~45%)和网状型(33%~49%)的形式存在。均匀硫酸盐化的结石增加较少(44%至48%)。Na2CO3处理增加了大孔的数量，导致所有颗粒的均匀硫酸盐化，几乎消除了正常情况下对石灰石类型和颗粒大小的强烈依赖。Na2CO3的作用被认为与形成共晶熔体有关，该熔体促进了离子扩散，加速了CaO的分子重排。用NaC l水溶液处理导致利用率降低，可能是由于形成大量共晶熔体而形成的大颗粒和堵塞气孔所致。Na2CO3的影响对加入量和燃烧环境(温度和气体组成)的敏感性低于Na2CO3。此外，Na2CO3既不会促进腐蚀，也不会形成氯化副产物，这是与氯化钠有关的主要问题。因此，Na2CO3在提高沸腾炉内石灰石固硫能力方面明显优于Na2CO3。
The ability of Na2CO3 and NaCl to enhance the sulfur capture capacity of three limestones was evaluated via fixed-bed calcination and sulfation experiments. The tested limestones represent three different sulfation morphologies: unreacted-core, network, and uniformly sulfated. Treatment with aqueous or powdered Na2CO3 significantly increased the Ca-utilization for two stones which normally sulfate in an unreacted-core pattern (20% to 45%) and network pattern (33% to 49%). The increase was lower for the uniformly sulfated stone (44% to 48%). Na2CO3 treatment increased the number of macropores leading to uniform sulfation of all particles, nearly eliminating the normal strong dependence of utilization on limestone type and particle size. The effect of Na2CO3 is believed to be associated with formation of a eutectic melt which enhances ionic diffusion and accelerates molecular rearrangement of the CaO. Treatment with aqueous NaCl solution caused a decrease in utilization, probably due to formation of large grains and plugging of pores caused by formation of a large amount of eutectic melt. The effect of Na2CO3 is less sensitive than that of NaCl to the amount added and the combustion environment (temperature and gas composition). In addition, Na2CO3 neither promotes corrosion nor forms chlorinated byproducts, which are main concerns associated with NaCl. Thus, Na2CO3 appears to have significant advantages over NaCl for enhancement of limestone sulfur capture capacity in fluidized-bed combustors.