Investigations of clathrate hydrate formation using advanced optical diagnostic techniques
File(s)
Author(s)
Bin Kamel, Muhammad Afiq
Type
Thesis
Abstract
Clathrate hydrates are crystalline compounds that are formed when water is in contact with a hydrate former. It is found in the ocean layer and typically require high pressure and low temperature to form solids. The stability provided by the guest molecule allows hydrate to maintain in solid phase above the freezing point of water. This creates a technological challenge to attain flow assurance in oil and gas pipelines. Cyclopentane is a good analogue for natural gas due to the mild conditions required for its formation. The lack of studies at conditions below the freezing point of water limits the observation of its morphology variations compared to other types of hydrate former. The unexplored area of hydrate research able to provide information with high spatio-temporal resolutions offers an opportunity to enhance our understanding of the phenomenon.
Characterisation of freezing and hydrate formation was carried out to distinguish the two phenomena at temperatures below 273 K. The subcooling temperature for cyclopentane was successfully extended to 15 K revealed a morphological transformation of hydrate from polygonal to spherulitic crystals. Planar laser-induced fluorescence technique was developed for temperatures between 263 to 283 K. Based on spectral analyses, nile red in cyclopentane (1.74 %/K) and sulforhodamine B and fluorescein 27 in water (2.88 %/K) showed improvements in temperature sensitivity compared to other dyes used in previous studies. Spatio-temporally resolved information of temperatures below 270 K suggest there is significant heat released during hydrate formation to warrant an increase in temperature compared to experiments in the absence of hydrate. Analysis of flow data showed convection dominating the flow in the surrounding phase. Lower velocities in the drop observed in the hydrate case compared to non-hydrate indicate that hydrate film at the interface acts to confine the flow in the drop.
Characterisation of freezing and hydrate formation was carried out to distinguish the two phenomena at temperatures below 273 K. The subcooling temperature for cyclopentane was successfully extended to 15 K revealed a morphological transformation of hydrate from polygonal to spherulitic crystals. Planar laser-induced fluorescence technique was developed for temperatures between 263 to 283 K. Based on spectral analyses, nile red in cyclopentane (1.74 %/K) and sulforhodamine B and fluorescein 27 in water (2.88 %/K) showed improvements in temperature sensitivity compared to other dyes used in previous studies. Spatio-temporally resolved information of temperatures below 270 K suggest there is significant heat released during hydrate formation to warrant an increase in temperature compared to experiments in the absence of hydrate. Analysis of flow data showed convection dominating the flow in the surrounding phase. Lower velocities in the drop observed in the hydrate case compared to non-hydrate indicate that hydrate film at the interface acts to confine the flow in the drop.
Version
Open Access
Date Issued
2025-01-31
Date Awarded
01/12/2025
License URL
Advisor
Markides, Christos
Sponsor
Majlis Amanah Rakyat
Publisher Department
Department of Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)