TY - JOUR
TI - First-principles study of calcium-based sulfur fixers and their products
AU - Chen Guoyan
AU - Chen Jianing
AU - Zhang Anchao
AU - Deng Haoxin
AU - Mei Yanyang
AU - Wen Xiaoping
AU - Wang Fahui
AU - Sheng Wei
AU - Shen Zheng
AU - Zuo Shuangshuang
JN - Thermal Science
PY - 2022
VL - 26
IS - 5
SP - 3843
EP - 3857
PT - Article
AB - Calcium-based sulfur-fixing agent, as the main sulfur-fixing product, is widely used in power plant boiler systems. In order to further study the thermodynamic properties and reaction characteristics of calcium-based sulfur fixing agent and its products, the method of combining power plant experiment with theory was used. The electronic structure, thermodynamic properties and density of states of quicklime, limestone, calcium sulfate (CaSO4) and calcium sulphoaluminate have been calculated based on the first-principles ultra-soft pseudopotential plane wave method of density functional theory. The generalized gradient approximation algorithm is used to optimize the structure of various minerals to achieve the most stable state. The results show that the enthalpy, entropy, specific heat capacity at constant pressure and Gibbs free energy of calcium sulfonate vary greatly from 25-1000 K, while the change of calcium oxide (CaO) is small, and that of calcium carbonate (CaCO3) and CaSO4 are between them. It shows that calcium sulphoaluminate has strong stability and more energy is needed to destroy the molecular structure of calcium sulphoaluminate. The CaO is the most unstable and requires less energy to react. The CaCO3 and CaSO4 are in between. The variation range of CaSO4 is greater than that of CaCO3, indicating that the stability of CaSO4 is higher than that of CaCO3. The experimental results show that the desulfurization efficiency of generating calcium sulphoaluminate is much higher than that of only generating CaSO4, indicating that calcium sulphoaluminate is very stable, which is consistent with the calculated results.