Development promotion of highly effective desulfurizers of calcium compounds by molecular dynamic simulatons

从理论上定量地阐述了碱金属化合物对脱硫特性的影响。利用热天平对石灰石进行了添加碱金属化合物和氯化物的脱硫实验。基于碱金属化合物的加入导致的化学和物理结构变化以及分子动力学模拟计算的CaO结构变化，阐明了CaO增强脱硫特性的机理。结果表明，在石灰石中加入NaCl对提高脱硫效率最为有效。为了更详细地阐明nacl掺杂对这种结构变化的影响，利用x射线衍射（XRD）分析了煅烧海贝、石灰石和nacl掺杂石灰石的晶体结构，结果表明，海贝和nacl掺杂石灰石中的CaO均呈结晶状，而煅烧后的石灰石中的CaO呈无序状。因此，nacl掺杂可以改变CaO的晶体结构。实验结果表明，焙烧后样品的晶体结构对脱硫性能有影响。其次，通过分子动力学模拟，模拟了纯CaO和nacl掺杂CaO的晶体结构，从理论上证实了nacl掺杂对CaO结构的影响。结果表明，在形成非晶结构的温度下，nacl的掺入有利于CaO的结晶。此外，在相同的计算条件和程序下，模拟了KC1和licl掺杂CaO。最后，只有NaCl稳定存在于CaO晶体中，而NaCl掺杂对CaO结晶的影响最大。这些趋势取决于每种碱金属氯化物的势能和离子半径的差异。实验和模拟结果表明，nacl的掺杂有助于CaO分子的结晶。少

The effect of the alkali metal compounds on the desulfurization characteristics was elucidated quantitatively and theoretically in this study. The desulfurization experiments by adding some alkali metal compounds and chlorides to limestone were carried out, using a thermobalance. The mechanism on the enhancement of desulfurization characteristics were elucidated, based on the chemical and physical change of structure due to alkali metal compounds addition as well as structure change of CaO calculated by molecular dynamics simulation. Obtained results show that addition of NaCl into the limestone was found to be the most effective on improving the desulfurization efficiency. In order to elucidate in details the effect of the NaCl-doping on such structure change, the crystal structures of calcined seashell, limestone and NaCl-doped limestone were analyzed by X-ray diffraction (XRD), Consequently, CaO in both seashell and NaCl-doped limestone was crystallized, whereas CaO in the calcined … More limestone was disordered. Therefore, NaCl-doping can change the CaO crystal structure. From those experimental facts, the desulfurization characteristics are influenced by result of the crystal structure of samples after calcination. Next, the crystal structures for pure CaO and NaCl-doped CaO were simulated, using molecular dynamics simulation, in order to confirm the effect of NaCl-doping on the CaO structure theoretically. The results show that NaCl-doping into CaO contributes to the crystallization of CaO even at the temperatures of formation of amorphous structure for the pure CaO. Additionally, KC1 and LiCl-doped CaO was simulated under the same calculation conditions and procedures. Finally, only NaCl stably exists as the CaO crystal, while NaCl-doping showed predominant effect on the CaO crystallization. These tendencies depend on the difference of the potential energy and ionic radius of each alkali metal chloride. The experimental and simulation results obtained suggested that NaCl-doping contributed to crystallizing the CaO molecules. Less