Assessment of industrial gas hydrate inhibitors using the 3-in-1 technique

Abstract

Suitability of a novel 3-in-1 technique to characterize industrial hydrate inhibitors was studied. Methane hydrates were formed using a concentration of 0.1 wt% of an unknown industrial inhibitor. Morphology, kinetics and phase equilibria characteristics of the system were observed. The technique provided reproducible data on morphology and growth mechanisms of the inhibited system. A leaf-like morphology was observed at lower degrees of subcooling, which resembles those found on some ethane or methane+ethane gas mixtures. Also hydrate structures were observed to remain in the liquid phase above the Hydrate-Liquid- Vapor Equilibrium temperature (THLV). THLV was found to be 279.79 0.01 K, discarding the studied inhibitor as a thermodynamic hydrate inhibitor (THI), at the concentration used. An increasing trend on THLV with the increasing dissociated hydrate fraction was observed. It was possible to identify the the unknown inhibitor as a kinetic hydrate inhibitor (KHI) and to rank its performance compared to other KHI and pure water-methane systems. The technique was found to provide quick and reliable information on the growth inhibition eect, and could be used as a tool to assess industrial inhibitors for later use on the field