Investigating the Effect of Crown Ether on the Kinetics and Morphology of Natural Gas Hydrate Formation

Abstract

In the field of gas hydrate research, additives have gained significant attention due to their exceptional promotional and inhibition effects in hydrate-based applications and flow assurance problems in the oil and gas industries, respectively. Therefore, in this work, we evaluate the performance of a new chemical (crown ether) for natural gas hydrate formation kinetics and morphology. A high-pressure stirred tank reactor with visual windows was employed to examine the performance of 18-crown-6ether (CE) for the formation kinetics of natural gas hydrate at high water-cut and high subcooling (∼21 K). Cyclopentane (1.5 mol % CP) was used as an additional hydrate former/oil phase. Experiments were conducted by using isothermal and cooling−heating methods of hydrate formation and dissociation. Various concentrations of CE, with a dosage ranging from 0.05 to 2.0 wt %, were assessed for hydrate formation kinetics, hydrate onset temperature, and morphological modifications. Cooling−heating experiments reveal that the hydrate onset temperature was significantly reduced in the presence of CE (60−70% reduction with respect to the baseline). Moreover, the hydrate formation kinetics/rate of hydrate growth was also reduced significantly in the presence of CE. Further, a unique behavior of CE was observed for the experiments performed in saline water (3.5 wt % NaCl in water). In saline water, hydrate formation kinetics was found to reduce in the presence of a low concentration of CE (0.05 wt %), while an enhanced growth rate was observed with a high concentration of CE (1.0 wt %). Our results may offer new insights into the usage of CE for various hydrate-based technologies as well as to manage hydrate formation in oil and gas pipelines.

New Hydrate Promoter to Enhance the Methane Hydrate Formation Kinetics: Applicable to Natural Gas Storage and Transport

“…The detailed description of the high-pressure visual reactor setup is illustrated in our previous articles, , and the schematic diagram is presented in Figure S1 in the Supporting Information. Briefly, a high-pressure stainless steel (SS316) reactor with a total volume of ∼150 cm 3 , coupled with two polycarbonate submarine-type visual windows, was employed in this study.…”

“…To investigate the kinetics of methane hydrate formation, the isothermal method of hydrate formation was used. , The details are given below: The sample was prepared while mixing BTA (concentrations ranging from 0.01 to 0.5 wt %) with 37.1 mL of DI water (in the case of 3:1 gas-to-liquid ratio). For the 6:1 and 8:1 ratio tests, the sample volumes were 22 and 16.5 mL, respectively.…”