(286h) Ionic Lqiuids As Dual Functional Inhibitors for Natural Gas Hydrates

Mohammad Tariq, Majeda Khraisheh, Mert Atilhan

Department of Chemical Engineering, College of Engineering, Qatar University, Doha, Qatar

Gas hydrates are ice-like crystalline compounds, where a gas (guest) is trapped within the hydrogen bonded network of water molecules (host). Gas hydrates are formed when water and gas molecules meet at low temperature and high pressures – conditions often encountered during gas processing. Gas hydrates can block pipelines which can result in shut down of the whole unit and ultimately costs massive amount of money and resources. Oil and gas industries spent substantial amount (15-20%) of production cost to avoid formation of gas hydrates in the pipeline during gas processing.

Although gas hydrates are industrially problematic compounds there are many useful aspects and applications of them in separation processes and energy storage. For such applications formation of hydrates with an optimum rate is required.

In this work, we have characterized methane hydrates formation conditions using a high pressure gas autoclave assisted with a magnetic stirrer. Total 18 sets of experiemnt were carried out for looking into the effect of a number of parameters such as: initial Pressure (100 bar and 40 bar), cooling rate (0.5, 1.0 and 2.0 ^oC/hr) and stirring rate (150, 300 and 500 rpm). The results were analyzed in the form of indiution time, rate of hydarte formation, change in torque and so on.

The results indicate that there is a sudden pressure drop as soon as the hydartes start to form and the time of such phenomena (induction time) dpends on the cooling rate and the stirring rate as well. When the cooling rate was high ( 2.0 ^oC/hr) and stirring rate was slow (150 rpm) no hydrates were formed. But in case of small cooling rate (0.5 ^oC/hr) and high stirring rate (500 rpm) hydrate formed instantly. It was also interesting to observe simultaneously the small change in temperature, drop in pressure and abruption in torque at the time of hydrate crystal formation.

This whole excercise gives useful information on the optimum conditions required for the rapid formation of gas hydrates for their use in separation and capturing processes.