Predicting the solubility of elemental sulfur in hydrogen sulfide through a molecular dynamics approach

Roles of Carbon Dioxide and Methane in the Dissolution of Elemental Sulfur in Natural Gas

“…Three sets of solvents are designed: 40 000 molecules in the binary H 2 S/CO 2 mixtures, 80 000 molecules in the ternary H 2 S/CO 2 /CH 4 mixtures, and about 100 000 molecules in the H 2 S/CO 2 /CH 4 /N 2 /C 2 H 6 mixture, respectively, which are large enough to produce steady results for the simulated systems. The simulations start with a supersaturated solution, and the solubility is estimated in the equilibrated solution by accounting for the S 8 molecules distributed in the solvent, as suggested in ref . To ensure the supersaturation in the starting solution, the S 8 /H 2 S ratio is carefully screened before the extensive simulations, which is ultimately set to 1:20 in the binary H 2 S/CO 2 mixture and 1:40 in the ternary and multivariate mixtures.…”

“…The number of S 8 molecules dissolved in the gas mixtures is thus denoted as the sum of S 8 clusters and left S 8 molecules when the equilibrium state of aggregation and dissolution is reached. The formation of a sulfur cluster is judged by the nearest interatomic distance between two S 8 molecules, which is set to 0.344 nm . Any S 8 molecule whose intermolecular distance is shorter than the criterion is considered in the cluster.…”

“…The low universality of these models indicates that further understanding to the sulfur dissolution mechanism is necessary. The dissolution mechanism at the molecular level is better described with molecular simulations, which are in fact widely used to predict the solubility of drugs in the aqueous solution. − The molecular simulations have been extended to the study of sulfur solubility − in the past years. For instance, Kadoura et al studied the sulfur solubility by exerting an empirical formula of the solid sulfur fugacity in the Monte Carlo simulations.…”

“…The dissolution and diffusion of a S 8 particle in H 2 S were simulated using the molecular dynamics (MD) method, and the solubility of S 8 was estimated by counting the number of S 8 molecules in the saturation zone. The reversed process from dispersion to aggregation of S 8 molecules in H 2 S was used to predict the sulfur solubility, which was found to have good computational efficiency and reproductivity. However, most MD simulations − were limited to the dissolution in pure H 2 S, which was unable to reflect the combined effect of the complex components in natural gas.…”

“…The reversed process from dispersion to aggregation of S 8 molecules in H 2 S was used to predict the sulfur solubility, which was found to have good computational efficiency and reproductivity. However, most MD simulations − were limited to the dissolution in pure H 2 S, which was unable to reflect the combined effect of the complex components in natural gas.…”