Abstract The characterisation and stability of coal slurries for introduction into an inductively coupled plasma optical emission spectrometer (ICP OES) and the application of slurries in the analysis of coal was investigated. The importance of rheology and the stability of the coal slurries on the analytical results produced by ICP OES was demonstrated. The homogeneity and stability of various coal slurries were characterised by sedimentation tests, scanning electron microscopy (SEM), zeta potential and viscosity measurements. The porosities and surface areas of different South African coals and a mechanism for the adsorption of the dispersants onto the coals were determined using low-temperature nitrogen physisorption studies. The possibility of partially solubulising the coal in N,N-dimethylformamide (DMF) was investigated. SEM indicated that DMF solubulised coal fines and that 0.1% (m/v) Triton X-100 with 10% (v/v) DMFresulted in well dispersed slurries relative to other dispersants (glycerol, PEI and water). Slurry analysis of coarse and ground coal in 0.1% (m/v) Triton X-100, showed that higher emission intensities and better precision was obtained when using ground coal. This was confirmed by lower RSDs (less than 5% for most of the elements analysed) relative to the unground, coarse coal. Glycerol slurries gave higher RSDs (higher than 5% for most of the elements) most of the time, thus negatively influencing the precision of measurement. Physisorption studies indicated that ground coal had up to ten times higher surface areas than coarse coal. The higher surface areas for fine ground coals suggested why they were better dispersed and thus better transported into the plasma, resulting in higher emission signals. Zeta potentials indicated that for all dispersants, the coal particles were well repelled from each other, although SEM pictures indicated better dispersion for 0.1% (m/v) Triton X-100 with 10% (v/v) DMF. It was demonstrated that higher intensities and higher precision could be obtained with well dispersed and stable coal slurries.

The first coal-fired power plant in Sri Lanka was successfully connected to the national grid in year 2011. The proposal of implementing coal-fired power plants in Sri Lanka has been appearing in power sector master plans since year 1985. It was delayed for many years, mainly due to public protests and indecision of the political leadership of the country. This research analyzes the social and economic barriers faced during the implementation stage. Operation of the plant in terms of system inertia, reliability and stability is discussed. This is the single largest power sector investment in Sri Lanka and returns on the investment were analyzed in this study. As this is the first coal-fired power plant in Sri Lanka, success of this project will create the platform for the public acceptance of future coal-fired power plants. There were some technical failures during the initial years of operation of the plant, and now it records a higher reliability. Furthermore, it is important to summarize the lessons learnt after implementing this project. Future plans of the utility, energy policy of the country and the political agenda of a country should reflect the experience with this project. This is a good example that teaches the lesson; projects which require to be implemented in the national interest should not be postponed or cancelled due to the protest by small groups of people perceived to be affected by the project. It is highlighted that system stability is improved in many cases due to the increase of power system inertia, to which this power plant makes the largest contribution. System inertia is improved in six out of nine scenarios, which were analyzed in this study. Economic benefits gained by the power plant were examined and the study proves that this power plant will have a significant positive effect on the national economy. Loss incurred delaying the project was calculated and it proves the importance of this project.

published_or_final_version / Geography and Geology / Master / Master of Philosophy

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