Phase Equilibrium Data and Model Comparisons for H₂S Hydrates

Abstract

Hydrogen sulfide is an exceptionally stable structure I (sI) gas hydrate forming guest molecule that is becoming increasingly prevalent in oil and gas production. However, phase equilibria data on pure hydrogen sulfide hydrate reported in the literature are relatively limited and inconsistent compared to other common hydrate formers such as methane or carbon dioxide. In this study, 61 hydrate phase equilibria measurements for sI hydrates containing hydrogen sulfide are reported in the temperature range from T = 273.68 K to 301.53 K and pressure range from p = 0.108 MPa to 1.960 MPa. Experimental data were measured using the isochoric pressure search (IPS) method which has been well established, as well as a modified IPS method, termed the phase boundary dissociation (PBD) method, which gives more efficient measurements of pure hydrate phase equilibria data. For example, it was shown in this work that using the new PBD method reduced the experimental run time to approximately 4.8 h per data point, compared to 40 h to 45 h per data point using the IPS method. The measured data for hydrogen sulfide hydrates were compared with predictions and experimental data reported in the literature, showing agreement between measurements and predictions within an average of 0.08 K for HydraFLASH 2.2 to 1.131 K for PVTSim 21 on average and literature within 0.21 K for Selleck et. al 10 to 1.42 K for Carroll and Mather 12 on average.

Gas Hydrate Formation Phase Boundary Behaviour of Synthetic Natural Gas System of the Keta Basin of Ghana

“…Prior to the study, a PVTSim sensitivity analysis was performed to validate the theoretical model and ensure reliable predictions. Ward et al [28] studied the hydrate equilibrium phase of H 2 S experimentally and validated his work using PVTSim and reported that, PVTSim could be accurately used for H 2 S hydrate equilibrium phase studies. In addition, Sule and Rahman [29] predicted the hydrate equilibrium phase of natural gas in the presence of H 2 S and inhibitor (methanol) using PVTSim.…”

High-Pressure Hydrogen Sulfide Experiments: How Did Our Safety Measures and Hazard Control Work during a Failure Event?

“…After the complete hydrate formation as visualized by a pressure halt, the formed hydrate was then dissociated by increasing the temperature stepwise by 0.2 K increments. An example of a pressure-temperature profile for liquid water-hydrate-H 2 S (g) and liquid water-hydrate-H 2 S (l) phase boundaries experiments, their results, and a more detailed explanation of the experimental work can be found elsewhere [13,22]. After the completion of each measurement, the H 2 S is released to (a) a dry gas trap, (b) a primary KOH scrubber, (c) a secondary KOH scrubber and (d) a final dry gas trap.…”

Effects of multiwalled carbon nanotubes on CH4 hydrate in the presence of tetra-n-butyl ammonium bromide

“…The point at which the slope of the P-T curve sharply changed was considered as the hydrate dissociation point. 32,34,35 2.4.2. Dynamics.…”