A large-scale pilot plant (0.43 m ID) was extensively modified and converted into an absorber/stripper system to demonstrate CO₂ capture technology using aqueous piperazine promoted potassium carbonate for coalfired power plants. Four pilot plant campaigns were completed. Three campaigns were conducted using 5 m K⁺/2.5 m PZ and 6.4 m K⁺/1.6 m PZ. Flexipac 1Y and Flexipac AQ Style 20 structured packing were used in the absorber. The stripper was tested with 14 sieve trays, IMTP #40 random packing, and Flexipac AQ Style 20 packing. Monoethanolamine (7 m) was tested in the third campaign to establish a base case. An approximate rate analysis showed that 5 m K⁺/2.5 m PZ is two times faster than 7 m MEA and three times faster than 6.4 m K⁺/1.6 m PZ. The location of the temperature bulge moves from the top of the column to bottom as the liquid to gas flow rate ratio is increased. Foaming occurred in the absorber in the first two campaigns and occurred in the stripper in the fourth campaign. Data from the pilot plant was used to develop a K⁺/PZ absorber model in Aspen Plus® RateSep[trademark]. The Hilliard (2005) Aspen Plus® VLE model and the kinetics developed by Cullinane (2005) were incorporated in the model. Data-Fit was simultaneously used to reconcile pilot plant data and perform a regression of the interfacial area and heat loss parameters for the RateSep[trademark] absorber model. The lean loading for the pilot plant data was shifted down by 10% to account for a discrepancy with the Cullinane vapor-liquid equilibrium data. The Data-Fit results showed that the average interfacial area for Flexipac 1Y was 80% of the value measure by the air-water column. The average interfacial area for Flexipac AQ Style 20 for 5 m K⁺/2.5 m PZ was 56% of the air-water measurement. The CO₂ heat of absorption may not have been adequately predicted by the RateSep[trademark] absorber model because the regressed values of heat loss were consistent with forced convection.

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1914. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed March 31, 2009)

Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references (leaves 140-144).

Thesis (M.E.S.)--Baylor University, 2006. / Includes bibliographical references (p. 101-106).

Thesis (Ph. D.)--School of Computing and Engineering and Dept. of Geosciences. University of Missouri--Kansas City, 2006. / "A dissertation in engineering and geosciences." Advisor: Anil Misra. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Oct. 30, 2007. Includes bibliographical references (leaves 210-220 ). Online version of the print edition.

This study has involved the investigation of the flows in a high efficiency cyclone separator and the performance characteristics of the cyclone when operating under the influence of base suction. It has long been accepted that a bleed taken from the base region of a cyclone could, generally, enhance the overall collection efficiency. However, detail analyses and investigations have been limited. This investigation has involved flow visualisation, laser Doppler anemometry, computational fluid Dynamics, as well as both model particle tests and full scale prototype tests to quantify the effect of base suction and cyclone performance. Flow visualisation has highlighted the extension of the vortices into the solid receiver at the base of the cyclone. The flow patterns in this region have been investigated and quantified using laser Doppler anemometry and this result compared to the predictions from computational fluid dynamics. Agreement between these results tends to be good in the inner vortex but less good in the outer vortex region. Model particle tests have shown that the extension of the vortices into the solid receiver results in the complete destruction of the dust layer in the receiver with the subsequent re-entrainment and carry over of particulate to the vortex finder. These particle tests have shown that this re-entrainment can be suppressed by the application of a suction in the base region and the overall collection efficiency improved. A bleed flow of 10% by volume is shown to give the maximum overall efficiency. Above this percentage the efficiency reduces. This trend in the results was also confirmed by full scale prototype tests.

Master of Science in Engineering by research: “A dissertation submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering.” Johannesburg, 05 February 2018 / In most industrial processes, energy is an integral part of the production process; therefore, energy consumption has become an intensified area in chemical engineering research. Extensive work has been done on energy optimisation in continuous operations; unlike in batch operations because it was believed that due to the small scale nature of batch plants, small amounts of energy is consumed. Certain industries such as the brewing and dairy industries have shown to be as energy intensive as continuous processes. It is, therefore, necessary for energy minimisation techniques to be developed specifically for batch processes in which the inherent features of batch operations such as time and scheduling are taken into account accordingly. This can be achieved through process integration techniques where energy consumption can be reduced while economic feasibility is still maintained. Most of the work done on energy minimisation either focuses on direct heat integration, where cold and hot units operating simultaneously are integrated, or indirect heat integration, where units are integrated with heat storage. The schedules used in these models are, in most cases, predetermined which leads to suboptimal results. This work is aimed at minimising energy consumption in multipurpose batch plants by using direct heat integration together with multiple heat storage vessels through mathematical programming. The proposed approach does not use a predetermined scheduling framework. The focus lies on the heat storage vessels and the optimal number of heat storage vessels together with their design parameters, namely size and the temperature at which the vessels are initially maintained, are determined. The formulation developed is in the form of a mixed integer non-linear program (MINLP) due to the presence of both continuous and integer variables, as well as non-linear constraints governing the problem. Two illustrative examples are applied to the formulation in which the optimal number of multiple heat storage vessels is not known beforehand. The results rendered from the model show a decrease in the external utilities, in the form of cooling water and steam, compared to the base case where no integration is considered and the case where only one heat storage vessel is used. / MT 2018

Mercury occurs naturally and as a result of human activities. One such activity is the combustion of mineral-enriched, sub-bituminous coal to produce electricityan industry that has existed for over 100 years. Although coal is absolutely necessary to supply the power that South Africa and its neighbouring countries requires, the emitted gases, especially mercury, impact the environment and present a complex array of health-related problems. Controlling the impact of mercury present in the environment depends on the efforts of governments, scientists, business and industry, agriculture, environmental organizations and individuals. Mercury is emitted from the point sources in different forms. Accurate determination of the emitted forms or species of mercury has become a global interest. Determination of the various mercury species requires several well-understood analytical techniques for the confident assessment of potentially contaminated samples. This study focuses on the development, validation and application of analytical methodologies that are capable of differentiating between the different forms of mercury in environmental samples (air, liquids and solids) from coal-fired power plants. Capillary electrophoresis with amperometric detection, high performance liquid chromatography with amperometric detection, and atomic fluorescence spectrometry methods were developed for mercury speciation. Very low detection limits observed using the methods. For capillary electrophoresis with amperometric detection, the detection limits were 0.005±0.002 μg/l for Hg2+ and 0.4±0.05 μg/l for MeHg+. Detection limits of 2±0.04 ppt and 0.01±0.02 μg/l for Hg2+ were observed for high performance liquid chromatography with amperometric detection and atomic fluorescence spectrometry respectively. These detection limits are attractive for the monitoring of mercury in the environment. Total mercury in solids (coal and ash) was measured by direct mercury measurement using a well-established method, involving the use of the mercury analyzer LECO AMA-254. Total gaseous mercury was measured using the Tekran 2537B system. On application to environmental samples, very good correlations in results were observed between the different methods. Mercury speciation in South African coal after acid extraction showed that only Hg2+ species was detected from the extracts and that 96% of total Hg in acid extracts is in the Hg2+ species form. Different trends in Hg speciation results at the Elandsfontein Air Quality Monitoring (AQM) station were observed over the sampling period. During winter sampling, Hg2+ was the predominant species, while Hg0 was predominant the species during summer sampling. Mercury speciation carried out at Duvha Power Station (units 1 and 2), equipped with fabric filter devices, revealed that the predominant form of Hg after the fabric filter devices was Hg2+, due to oxidation of Hg0 to Hg2+ as the flue gas temperature decreases. Mercury speciation at the Majuba Underground Coal Gasification flare revealed that although mercury is emitted from power plants in the form of different chemical species, with each species have a different fate in the atmosphere, the climate, wind direction and terrain also play roles in the transport of mercury emissions. Therefore, it is difficult to predict the transport patterns of emissions. Nonetheless, with correct measuring equipment and modelling, the patterns of emissions should be able to be predicted. The patterns observed and data recorded at the Elandsfontein AQM station and Duvha Power Station, respectively, were however, insufficient to permit accurate modelling. This study raised a number of other questions which are too comprehensive for this study to address. Therefore, more comprehensive atmospheric and combustion studies should be done.