Gas hydrates inhibition via combined biomolecules and synergistic materials at wide process conditions

Abstract

The motive of this research to present a systematic study in context of implementation of gas hydrate inhibitors that are obtained via naturally occurring amino acids (L-Alanine, Glycine, L-Histidine, L-Phenylalanine and L-Asparagine). These materials are tested for methane (CH4) hydrate inhibition purposes from both thermodynamically and kinetically perspectives at wide process conditions. In this presented work, all studied amino acids have been tested at both 1 wt % as low dosage inhibitors as well as at higher concentrations up to 5 wt %. Furthermore, Polyethylene-oxide (PEO) and Vinyl Caprolactum (VCap) were used at 1 wt % in studied aqueous solutions as synergetic compounds to enhance the inhibition performance for CH4 hydrate inhibition. Gas hydrate experiments were carried out by using rocking cell apparatus, from which pressure, temperature equilibrium data were obtained at recorded time and these data were translated into inhibitor performance evaluation from both thermodynamics and kinetic inhibition perspectives. This study includes the discussions of the effect of solubility limitation of studied amino acids, the effect of inhibitor concentration effect on the thermodynamic shift of the hydrate equilibrium curve, the role of side chain in amino acids in kinetic hydrate inhibition, the hydrophobic interactions of alkyl chain in water for synergistic point of view. The results showed that the suitability of amino acids combined with synergistic materials for high kinetic inhibition performance, which provided an additional time shift up to 35 h in hydrate formation at moderate process conditions up to 55 bars, specifically when L-Alanine was used.