No description available.

Gas cleaning is an essential step in many chemical processes. The reason for cleaning is to remove components that can damage equipment or inhibit further reactions. The treatment can include the removal of particulates, removal of one or more chemical species, or the conversion of one species to another. The gases include natural gases, combustion gases or synthesis gas (syngas). Of particular importance is the hot gas desulphurization (HGD) of syngas after gasification. This method of treatment offers potential energy and raw material savings to traditional ‘wet’ gas cleaning methods, such as physical or chemical absorption. Syngas is a valuable intermediate product because it can be processed into a number of different chemicals. These range from hydrocarbon chains (Fischer-Tropsch reactions), methanol, and ammonia (from hydrogen in the syngas). Methanol and ammonia are important raw materials to produce other chemicals. Syngas can be used for production of electricity via gas turbines in an Integrated Gasification Combined Cycle (IGCC) plant. In this study, a laboratory scale gasification and desulphurization unit was designed and constructed for removal of hydrogen sulphide (H2S) from syngas. The gasifier operates at moderately high temperature (700-900 °C) and low pressure (1-3 bar g) to produce syngas containing H2S (1-6 mol %) from a liquid hydrocarbon fuel mixture and oxygen. Desulphurization occurs in a fixed bed isothermal reactor (300-600 °C) whereby H2S is removed by chemical reaction with a sorbent. The fuel used was a mixture of methanol and ipropanethiol and the sorbent chosen was zinc oxide. The apparatus was tested to obtain a reliable experimental method. A series of experiments were conducted to determine two results: Firstly, to see the performance of the unit during repeated sorbent testing (i.e. a systematic experimental run programme). Secondly, to determine the effect of some process variables (temperature, flowrate and particle size) on the conversion of sorbent. GC analysis of the syngas showed consistent gas composition during the experiment, an important result which justifies this new method of syngas production from a liquid fuel. The final conversions from ZnO to ZnS ranged from 2-12 mole %. However, there was some variation under repeated conditions, which showed the need for additional method development. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

In recent decades the knowledge of nitrous oxide (N2O) emissions after the application of nitrogen (N) fertilizers in agriculture soil has improved. However the understanding of emissions of N2O from Canadian organic agricultural systems has not been developed. The Glenlea Long Term Crop Rotation is the longest running organic conventional comparison study in western Canada and was used here to compare N2O emissions between the systems. In organic cropping systems forage legumes such as alfalfa are incorporated into the soil as an N source. The amount of N2O that is emitted after the incorporation and during the subsequent crop is not well known. The wheat and legume phases (alfalfa (Medicago sativa) in organic system and soybean (Glycine max L.) in the conventional) of the rotation were monitored for N2O. In 2014, 2015, and spring 2016 (data still being analysed) emissions of N2O were monitored using the vented static chambers method as well, soil conditions (temperature, moisture, inorganic N and extractable carbon) and yields were measured. Typical N2O emissions from spring applied urea were observed after application in the conventional system however no emission episode was seen after the fall alfalfa plough down or during spring thaw in the organic system. Greater NO3- accumulation was observed in the organic treatments however low emissions were observed. The organic system resulted in lower yields for both years, but still resulted in lower emissions per amount of grain produced (yield-scaled emissions) than the conventional system. This study adds to the knowledge that N2O emissions from organic systems do differ from conventional however yields need to be improve to fully exploit the benefits. / February 2017

Frequency domain analysis tools have been developed to analyse simultaneous multi-point measurements of developed space plasma turbulence. The Coherence Length technique enables the scale length for plasma wave structures to be measured from magnetic field measurements. The coherence length defines a length scale for the measurement of wave phenomena. Single satellite measurements can be used, the technique becoming more reliable with higher numbers of satellites. The technique is used to identify coherence lengths for waves observed in the magnetic field near the bow shock by the dual AMPTE-UKSIAMPTE-IRM satellites, and for mirror wave structures observed in the magnetic field in the magnetosheath by the dual ISEE-lIISEE-2 satellites. The Transfer Function Estimation technique enables the transfer of energy between plasma waves to be measured, from simultaneous dual-point measurements, resulting in linear growth / damping rates and second-order wave coupling. The technique is improved by replacing the Least Squares method for inversion with Regularisation. The technique is applied to simultaneous magnetic field measurements near the bow shock by the AMPTE-UKSIAMPTE-IRM satellites, where a linear instability in the wave field is identified, which is attributed to an ion anisotropy instability, and accompanying sequence of second-order three-wave coupling processes is also identified, which dissipates the energy from the linear instability. The Wave vector Determination technique enables the identification of wave vectors from simultaneous four-point measurements. The availability of four-point measurements means that the reliance on Minimum Variance Analysis, and that of only being able to use magnetic field measurements, is removed, the wave vector can be determined unambiguously directly from the magnetic field measurements. The technique can identify between waves of different frequency, and waves at the same frequency but propagating in different directions. The technique is applied to simultaneous observations of the electric field by the four-point ii Cluster II satellites, enabling the determination of the wave vector and the identification of a mirror mode structure, solely from the electric field measurements. Chapter 1 introduces the solar-terrestrial environment, briefly describing exploration of this environment by man-made satellites and listing some aims of the analysis of data collected by the satellites. Chapter 2 elaborates on what is meant by data analysis; Spectral Transforms are introduced and described, with a comparison made between Fourier Transforms and Wavelet Transforms, before a review is made of current data analysis techniques for satellite data. Chapter 3 defines and focuses attention on the objectives of this thesis, which are addressed in the following three chapters. Chapter 4 investigates the coherence length of plasma waves through use of the Wavelet Transform and the Fourier Shift Theorem. Chapter 5 makes estimates of wave Transfer Functions, replacing an established Least Squares inversion technique with a Regularisation inversion. Chapter 6 uses a method to determine wave propagation directions, from multi-satellite data, that has not been applied before due to the lack of availability of suitable data sets. Chapter 7 summarises the preceding chapters. The Appendices contain reprints of papers resulting from, and relating to, this research.

The recombination rate coefficient for molecular helium ions has been measured in a pulsed afterglow at 1.86 Torr as a function of electron temperature and electron density without making a priori assumptions about the functional dependence. The concentrations of the molecular ions and electrons were measured and the source terms for the molecular ions were included in the rate equation.

Criteria for the confinement of plasmas consisting of a positive and negative component in Penning type traps with nested electric potential wells are presented. Computational techniques for the self-consistent calculation of potential and plasma density distributions are developed. Analyses are presented of the use of nested well Penning traps for several applications. The analyses include: calculations of timescales relevant to the applications, e.g. reaction, confinement and relaxation timescales, self-consistent computations, and consideration of other physical phenomenon important to the applications. Possible applications of a nested well penning trap include production of high charge state ions, studies of high charge state ions, and production of antihydrogen. In addition the properties of a modified Penning trap consisting of an electric potential well applied along a radial magnetic field are explored.

Ongoing conversion of forests in Sumatra to agricultural lands might affect the biodiversity of soil fauna, such as termites, and emissions of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). To assess the impact of such forest conversions, this study was conducted in Jambi, Sumatra in an undisturbed forest (FR), a disturbed forest (DF), a one year old rubber plantation (RB1), a twenty year old rubber plantation (RB20) and an oil palm plantation (OP). The plantations belonged to smallholders and were not usually fertilized. The effect of fertilizer was assessed by applying N fertilizer and taking a series of intensive measurements. The N2O, CH4 and CO2 fluxes were measured using static chamber methods and termite species richness was assessed using a standard semi quantitative transect method. Forest conversion to smallholder plantations did not significantly affect the N2O, CH4 and CO2 fluxes, but the diversity and relative abundance of termites was decreased. this implies that the ecosystem services regulated by termites might decline. The application of N fertilizer at the conventional rate (141 kg N ha-1 y-1), with an emission factor of 3.1 % in the oil palm plantation, increased N2O emissions to twice as high as that in the undisturbed forest. The annual N2O and CH4 fluxes from termites amounted to 0.14, 0.21, 0.88, 2.47 and -0.56 kg ha-1 y-1 N2O-N and 0.85, 1.65, 3.80, 0.97 and 2.30 kg ha-1 y-1 CH4-C in the FR, DF, RB1, RB20 and OP, respectively. Further research is needed to understand the interannual variability of the N2O, CH4 and CO2 fluxes from soils and termites. Understanding the key drivers and underlying processes which regulate them would help to control the biodiversity loss and the change of N2O, CH4 and CO2 fluxes from soils and termites.

This work describes the oxidation of organic compounds in an argon/water continuous flow plasma reactor. Water insoluble materials such as alkanes and alkenes, in particular n-pentane to n-octane, 1-hexene, cyclohexane and cyclohexene have been functionalized with different functional groups: hydroxy-group, hydroperoxy-group, oxo-group and double bond. Fragmented alcohols, aldehydes and carboxylic acids have also been observed. A detailed set of radical reactions, for the attack of n-hexane and its derivatives by the hydroxyl radical, have been proposed and are supported by quantum mechanical calculations. Electron impact reactions are considered as complementary pathways. A comprehensive network of reaction pathways has been generated, which proofed to be sufficient to predict correctly the majority of the observed products for starting materials of other chain lengths or related alkenes. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2015. / November 12, 2015. / Hydrocarbon, Hydrogen peroxide, Hydroperoxide, Hydroxyl Radical, Oxidation, Plasma Reactor / Includes bibliographical references. / Igor V. Alabugin, Professor Directing Dissertation; Bruce R. Locke, University Representative; Gregory B. Dudley, Committee Member; Timothy Logan, Committee Member.

No description available.

En el presente trabajo de tesis, se realizó un análisis de evaluación comparativa del consumo de combustible e índices de emisiones de un vehículo liviano funcionando con dos mezclas de gasolina y etanol (E7,8 y E10) en Lima Metropolitana. El vehículo, de marca Hyundai modelo Santa Fe, fue instrumentado e implementado adecuadamente mediante un único sistema de adquisición de datos para obtener un registro en tiempo real del consumo de aire de admisión de motor, las emisiones de gases de escape, la distancia recorrida y la velocidad del vehículo, y las condiciones ambientales durante las pruebas. La campaña experimental se desarrolló en dos circuitos de conducción urbana en Lima Metropolitana: circuito en condiciones de tráfico y circuito a velocidad constante. Las pruebas fueron realizadas en un periodo aproximado de dos semanas, tratando de asemejar las condiciones de operación: hora de inicio, carga del vehículo, presión de neumáticos entre otros. De los resultados obtenidos en condiciones de tráfico, se constató que el consumo de combustible prácticamente no fue alterada al incrementar el contenido de etanol en el gasohol comercial (E7,8). En cambio, para el circuito a velocidad constante, el consumo de combustible aumentó en 11,2 % al incrementar el contenido de etanol. Con respecto a los índices de emisiones calculados (g/km) en condiciones de tráfico, estos presentaron una mejora en reducción al usar E10 bajo condiciones de tráfico, ya que con E10 se obtuvo un índice de emisión de 91,71 mg/km de NOX, 208,70 mg/km de HC, 14.24 g/km de CO y 273,80 g/km de CO2, mientras que utilizando E7,8 el vehículo emitió 102,61 mg/km de NOX, 232,44 mg/km de HC, 15,00 g/km de CO y 277,74 de CO2. El consumo de combustible promedio (km/L) y todos los índices de emisiones (g/km) disminuyeron, significativamente, indiferente del tipo de combustible (E7,8 o E10), en condiciones a velocidad promedio constante respecto a condiciones de tráfico. Finalmente, el estudio concluye que el E10 representa una alternativa económicamente y ambientalmente viable debido a los resultados de desempeño y emisiones obtenidas en el presente estudio. / Tesis