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

本文从理论上和定量上阐明了碱金属化合物对脱硫特性的影响。在热天平上进行了石灰石中添加碱金属化合物和氯化物的脱硫实验。根据碱金属化合物的加入引起的结构的化学和物理变化以及分子动力学模拟计算的CaO的结构变化，阐明了其脱硫性能增强的机理。实验结果表明，在石灰石中添加NaCl对提高脱硫效率最为有效。为了详细阐明NaCl掺杂对这种结构变化的影响，采用X射线衍射（XRD）分析了煅烧贝壳、石灰石和NaCl掺杂石灰石的晶体结构，结果表明，贝壳和NaCl掺杂石灰石中的CaO都结晶化，而煅烧贝壳中的CaO则结晶化。 ...更多信息 石灰岩是无序的。因此，NaCl掺杂可以改变CaO的晶体结构。从这些实验事实来看，煅烧后样品的晶体结构对脱硫性能有很大影响。接下来，为了从理论上确认NaCl掺杂对CaO结构的影响，使用分子动力学模拟来模拟纯CaO和NaCl掺杂CaO的晶体结构。结果表明，NaCl掺杂有利于CaO的晶化，即使在纯CaO形成非晶结构的温度下也是如此。此外，在相同的计算条件和程序下，KCl和LiCl掺杂的CaO进行了模拟。最后，只有NaCl作为CaO晶体稳定存在，而NaCl掺杂对CaO结晶表现出主导作用。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掺杂有助于结晶的CaO分子。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