Water content of liquid H2S in equilibrium with the hydrate phase

Abstract

Acid gas injection containing H2S is one strategy for managing atmospheric sulfur emissions where sulfur recovery may not be feasible or economical in some locations. Apart from its toxicity and corrosivity in wet environments, H2S forms a high temperature hydrate in the presence of water, which can cause issues such as plugging of transport pipelines or injection wellheads. Before transportation to injection, liquid water is removed from an injectate within the interstage suction scrubbers before each compression cycle and/or by further dehydration. Water content data are important in order to determine and define the dehydration requirements of acid gas injectates. Prior to this work, there were no water content data for H2S at hydrate forming conditions because of the difficulties in measuring low concentration of water above hydrates and high H2S toxicity. In this study, we report the water content of pure H2S in the hydrate forming regions from p = 4.178 to 20.572 MPa and T = 247.65 to 298.28 K using tunable diode laser spectroscopy. The measured data show a relative water content difference of ca. 2.5% from the model reported in this work using the Sloan et al. (1976), and van der Waal & Platteeuw (1959) equations for the hydrate phase, and the fluid phase model of Bernard et al. (2012).