Influence of reboiler retention time and concentration of thermally degraded MEG on thermodynamic inhibition performance

Mono ethylene glycol (MEG) is highly utilized during gas production to mitigate hydrate formation issue. However, exposing the MEG to reboiler higher temperatures during distillation will lead to the reduced hydrate inhibition performance of the MEG due to thermal degradation and accumulation of organic acids such as glycolic, acetic and formic acids. The hydrate inhibition performance of the thermally degraded MEG was measured isobarically for pure methane gas using a cryogenic sapphire cell for the pressure ranges of 5500 to 20500 kPa. The objective is to determine and optimize the thermodynamic hydrate inhibition performance of thermally degraded MEG influenced by reboiler operation and MEG concentration in the lean MEG product.This research determines that operating the reboiler at high MEG concentration of 80.8 vol % for longer durations of 6.0 h raises the dissociation temperature by an average of 1.4 °C compared to 0.9 °C for the lower MEG concentration of 40.2 vol % for similar duration of 6.0 h. This suggests that lower MEG concentration will yield lower dissociation temperatures at the same retention time. Hence, the MEG thermodynamic inhibition performance is optimal at lower MEG concentration which results in lower dissociation temperature.