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
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 isused 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 25K to 1000K, while the change of calcium oxide is small, and that of
calcium carbonate and calcium sulfate are between them. It shows that
calcium sulphoaluminate has strong stability and more energy is needed to
destroy the molecular structure of calcium sulphoaluminate. Calcium oxide is
the most unstable and requires less energy to react; Calcium carbonate and
calcium sulfate are in between. The variation range of calcium sulfate is
greater than that of calcium carbonate, indicating that the stability of
calcium sulfate is higher than that of calcium carbonate. The experimental
results show that the desulfurization efficiency of generating calcium
sulphoaluminate is much higher than that of only generating calcium sulfate,
indicating that calcium sulphoaluminate is very stable, which is consistent
with the calculated results.