Novel methods predict equilibrium vapor methanol content during gas hydrate inhibition

In economic and safety hazards points of view, it is crucial to avoid the formation of clathrate hydrate of gases in oil and natural gas transportation/production systems. Injection of methanol as a thermodynamic inhibitor is a common approach in industry to shift the hydrate phase boundary to higher pressures/lower temperatures. Accurate computation of methanol loss to the vapor phase within hydrate inhibition is essential to calculate the right injection rate of methanol. In this study, two procedures have been proposed for fast and precise estimating the ratio of methanol content of vapor phase to methanol liquid composition (R_MeOH). In the first method, a new mathematical expression is presented. The obtained correlation is reliable for temperatures between 267.15 and 279.15 K and pressures between 1160 and 28000 kPa. The second method employs artificial neural network (ANN) approach for R_MeOH prediction. Both developed models results are in good agreement with reported data in literature. The ANN based model, however, is more accurate than the new correlation.