Performance of Methane Hydrate Formation In the Presence of Low-Dosage Poly (Ethylene Oxide)

Time dependent isochoric formation of methane hydrate was investigated in the presence of low-dose poly (ethylene oxides) (PEOs 0.1-1 %w/v). The effect of different molecular weights (MW~4, 20 and 1000 kD) of PEO on methane hydrate nucleation time and storage capacity was studied and compared at concentration of 0.5% w/v PEO. Methane hydrate was isothermally formed at 4 oC and initial pressure of about 90 bar. Kinetic measurements revealed a triple effect of PEO (including promotion, inhibition and stabilization effects) on methane hydrate formation. The nature and type of the effect arises from the difference in molecular weights and concentration ranges of PEOs. These parameters directly affect the nucleation time and storage capacity of methane hydrate. Generally, in comparison with the pure water, PEO improved the storage capacity of methane hydrate. Results showed that PEO (1000 kD) at concentration of 0.5% w/v gives significant kinetic inhibitory performance enhancements, while PEO (20 kD) at the same concentration (0.5% w/v) was found to be an excellent promoter upon methane hydrate formation. On the other side, PEO (1000 kD) at concentration of 0.25% w/v was an efficient low-dosage hydrate stabilizer along with producing gas-rich methane hydrate suitable for gas fuel storage and transportation

Keywords:

Gas hydrate , Polyethylene oxide , Inhibitor , Promoter , Stabilizer