UQ eSpace

Abstract

Natural gas gradually becomes one of the major energy resources in the world. Due to the growing demand for energy consumption and increasing environmental concern, natural gas has an optimistic future market especially compared with other fossil fuels. The issue for utilizing natural gas broadly is that the difficulties exist in transport and storage since the proven natural gas reserves are dispersedly distributed over the world. High-cost and high-risk gaseous or liquified natural gas transport and storage limited the global application of natural gas. In this project, the liquid hydrocarbon, cyclopentane, was selected for the hydrate formation and dissociation experiment since its hydrate structure is the same as natural hydrate structure but can be easily formed under near ambient conditions. Three types of salt solutions, sodium chloride (NaCl), calcium chloride (CaCl2), and aluminium chloride (AlCl3) solutions in different molality concentrations were prepared. The formation experiment was conducted by cooling down the mixture of cyclopentane and salt solution in a cryostat at atmospheric pressure. Temperature probes were placed in the solution phase. The dissociation experiment started when sufficient hydrates formed. A quick dissociation method was applied to the cyclopentane phase equilibrium temperature measurement. The experimental phenomena and equilibrium temperature were observed visually. The phase equilibrium temperature data for cyclopentane hydrates were measured from the experiment. The collected data were progressed and plotted over the concentrations (mass fraction, molality, effective mole fraction, and ionic strength). Possible relationships were proposed and analysed. In addition, some preliminary experiments had been conducted to obtain supporting information and data. Hydrate formation rate was improved by increasing subcooling and introducing agitation. In this thesis, the phenomena of cyclopentane hydrate formation and dissociation had also been observed visually during the experiments. The equilibrium temperatures gathered from this thesis can be applied for further studies. A slower dissociation method can be used to obtain the equilibrium data with high accuracy. Furthermore, the reliable data may be applied for relationship studies on cyclopentane hydrate nucleation rate and effective mole fraction in electrolytes under the same subcooling level.