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<p>Pollution problems have drawn worldwide awareness and become significantly important now. Particulate matter (PM) emission is one of the key pollution issues. Particulate matter has a significant impact on the environment and human health, especially particle sizes that range below 10μm. Researches continuously work an improvement of fine particulate matter collections emitted from all kinds of sources, such as automobiles, industrial combustion, etc. Governments in many countries are planning to regulate the PM emission from the existing PM_10 (particle diameter<10μm) to new limits PM_2.5 (particle diameter<2.5μm) within the next few years. For this reason, present PM control system needs to be improved.</p><p>The objective of this work is to develop a dust flow separator type electrostatic precipitator (DFS-ESP) for the effective control of fine particulate matter emission from natural gas combustions. The characteristic of PM emitted from natural gas combustion is studied, and the performance of a DFS-ESP is evaluated by experiments and numerical predictions.</p><p>An experiment was conducted for natural gas combustion exhaust flow rates from 2.5 to 9 Nm^3/h, ESP applied voltages from 0 to 30kV, and gas temperature from 80 to 160°C. A series of particle measurements were conducted at upstream, downstream and middle of the DFS-ESP system by an optical particle counter for particle mass density, and by condensation nucleate particle counter for particle size distributions and particle number density. Particle sampled from the natural gas combustion system was also analyzed by an environmental scanning electron microscope (ESEM) technique. Flow velocity profile and pressure drop of the DFS-ESP were measured by a Pitot tube and diaphragm type pressure transducer, respectively.</p><p>The experimental results show that the particle size emitted from natural gas combustion ranges from 17 to 300nm in diameter, and the volume density is approximately from 5 x 10^8 #pt/m^3 to 5 x 10^9 #pt/m^3 depending on the combustion conditions. The dust flow separator can concentrate 90% of fine particles in 1 to 3% of the gas flow and divert it from the main flow to the ESP section where the particles can be removed. In terms of overall particle collection efficiency, the DFS-ESP system can remove up to 90% of the particles based on the number density. The pressure drop across the DFS-ESP is observed to be lower than lPa for the present range of flow rate, which is within acceptable limits for industrial applications.</p> / Thesis / Master of Applied Science (MASc)

<p> Pollution problems have drawn worldwide awareness and become significantly important now. Particulate matter (PM) emission is one of the key pollution issues. Particulate matter has a significant impact on the environment and human health, especially particle sizes that range below lOJJ.m. Researches continuously work an improvement of fine particulate matter collections emitted from all kinds of sources, such as automobiles, industrial combustion, etc. Governments in many countries are planning to regulate the PM emission from the existing PM10 (particle diameter<10μm) to new limits PM2.5 (particle diameter<2.5μm) within the next few years. For this reason, present PM control system needs to be improved. </p> <p> The objective of this work is to develop a dust flow separator type electrostatic precipitator (DFS-ESP) for the effective control of fine particulate matter emission from natural gas combustions. The characteristic of PM emitted from natural gas combustion is studied, and the performance of a DFS-ESP is evaluated by experiments and numerical predictions. </p> <p> An experiment was conducted for natural gas combustion exhaust flow rates from 2.5 to 9 Nm^3/h, ESP applied voltages from 0 to 30kV, and gas temperature from 80 to 160°C. A series of particle measurements were conducted at upstream, downstream and middle of the DFS-ESP system by an optical particle counter for particle mass density, and by condensation nucleate particle counter for particle size distributions and particle number density. Particle sampled from the natural gas combustion system was also analyzed by an environmental scanning electron microscope (ESEM) technique. Flow velocity profile and pressure drop of the DFS-ESP were measured by a Pitot tube and diaphragm type pressure transducer, respectively. </p> <p> The experimental results show that the particle size emitted from natural gas combustion ranges from 17 to 300nm in diameter, and the volume density is approximately from 5 x 10^8 #pt/m^3 to 5 x 109 #pt/m^3 depending on the combustion conditions. The dust flow separator can concentrate 90% of fine particles in 1 to 3% of the gas flow and divert it from the main flow to the ESP section where the particles can be removed. In terms of overall particle collection efficiency, the DFS-ESP system can remove up to 90% of the particles based on the number density. The pressure drop across the DFS-ESP is observed to be lower than lPa for the present range of flow rate, which is within acceptable limits for industrial applications. </p> / Thesis / Master of Applied Science (MASc)

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa presently faces a serious and much-acknowledged energy capacity deficit. The Department of Energy are determined to address this capacity crisis by creating several new power plants between 2010 and 2030, as stipulated in the “Integrated Resource Plan 2010”. A Combined Cycle Gas Turbine (CCGT) power plant is proposed to add 2370 MW of capacity to the national grid. The “new-build” CCGT plant will use natural gas as a feedstock for energy generation. The plant is destined to begin energy generation by 2019, and will ramp up to full capacity by 2030. Following a review of the existing natural gas sources and the nascent gas network in South Africa, Liquefied Natural Gas (LNG) has been identified as the most suitable immediate source of natural gas feedstock for the CCGT. LNG fuel must be imported into South Africa aboard large, special purpose LNG Carrier (LNGC) vessels. LNGC vessels require a designated marine import terminal in order to offload the super-cooled and potentially flammable cargo. Saldanha Bay, located on the South West coast of South Africa, has been selected by Transnet as a preferred location for LNG terminal development. A review of LNG technology reveals the need for mandatory onshore LNG storage and regasification facilities, land area requirements, demands of different LNGC types and the characteristics of dedicated LNG jetties and terminals. Floating, offshore and traditional LNG terminals are discussed. The objective of this thesis is to review potential terminal sites and conceptual layouts in Saldanha Bay, and via a Multi Criteria Analysis, to present three distinct LNG terminal layout options for further consideration. The conceptual layouts will address technical concerns such as berth orientation and layout, safe navigational access to the terminal, mandatory onshore infrastructure and optimisation of berth operations. Saldanha Bay as a port location is studied and the importance of local environmental features is highlighted. Potential terminal development sites are identified following a review of nautical and terrestrial restrictions. Four conceptual site layouts are proposed, providing jetty locations and orientations in the Bay. The sites are located in North Bay, Hoedjiespunt, and two in Big Bay. Several Key Design Parameters (KDP’s) are identified as having a critical bearing on the ultimate layout, operation and feasibility of an LNG terminal in Saldanha Bay. The sensitivity and influence of the KDP’s at each of the four conceptual sites is investigated. Analysis of KDP effects leads to the development of design variation options at the sites. Twelve terminal layout schemes are ultimately derived. A Multi Criteria Analysis (MCA) is performed to rank the 12 terminal layout schemes in terms of technical efficacy. A sensitivity study is conducted to justify the selection of MCA parameter weights. The three top-scoring schemes are recommended for more detailed pre-feasibility investigation. The three terminal layout schemes, located in Big Bay and Hoedjiespunt, make use of both standard trestle jetties and floating LNG technologies. The thesis has shown that a number of viable sites and layouts for LNG terminals exist in Saldanha Bay and demonstrates a systematic analysis of design issues leading to preferred options. The thesis concludes by outlining the next steps in the process towards a final terminal scheme selection. / AFRIKAANSE OPSOMMING: Suid-Afrika ervaar huidig ‘n drastiese energie kapasiteit verlies. Die Departement van Energie is vasbeslote om die energie krisis aan te spreek deur verskeie nuwe kragstasies tussen 2010 en 2030 op te rig, soos beskryf in die “Integrated Resource Plan 2010”. ‘n Gekombineerde Siklus Gas Turbine (GSGT) kragstasie is voorgestel om ‘n verdere 2370 MW by te voeg tot die nasionale krag netwerk. Die “nuut-geboude” GSGT kragstasie sal natuurlike gas as brandstof vir kragopwekking gebruik. Die kragstasie is beplan om teen 2019 krag op te wek, en sal teen 2030 volle kapasiteit loop. Na ‘n ondersoek van die bestaande natuurlike gas bronne en gas netwerke in Suid Afrika, is Vloeibare Natuurlike Gas (VNG) geïdentifiseer as die huidiglike beskikbare bron van brandstof vir die GSGT. VNG moet ingevoer word aanboord spesiaal geboude VNG vaartuie. VNG vaartuie benodig ‘n spesifieke mariene invoer terminaal om die vlambare vloeistof mee af te laai. Saldanhabaai, aan die Suid-Westerlike kus van Suid Afrika, is as verkose area vir die VNG terminaal ontwikkeling geïdentifiseer deur Transnet. ‘n Oorsig van VNG tegnologie bevind dat VNG stoorplek en vergassings fasiliteite, land area, verskeie VNG vaartuie en karakteristieke van VNG terminale benodig word. Verskeie VNG terminale word bespreek in hierdie studie. The doel van hierdie tesis is om die potensiële terminaal bou-terrein en konseptuele ontwerpe in Saldanhabaai, deur middel van ‘n multi-kriteria analise (MKA), in drie verskillende ontwerp moontlikhede voor te stel. Saldanhabaai, as hawe, is bestudeer en belangrike omgewings aspekte is geïdentifiseer. Potensiële terminaal bou-terrein is geïdentifiseer na aanleiding van seevaart en land beperkings. Vier konseptuele bou-terreine is voorgestel wat jetty posisies en orientasies aandui. Die bou-terreine is in Noordbaai, Hoedjiespunt, en twee in Big Bay. Verskeie Sleutel Ontwerp Parameters (SOP’s), wat ‘n kritieke rol speel in die uiteindelike orientasie, werking en effektiwiteit van die VNG terminaal in Saldanhabaai, is geïdentifiseer. Die sensitiwiteit van die SOP’s by elk van die vier voorgestelde moontlikhede, is ondersoek. ‘n Ontleding van die effek van die SOP’s het variasie in die ontwerp moontlikhede by die verskillende bouterrein tot gevolg. Twaalf terminaal orientasie skemas is voorgestel. ‘n MKA is uitgevoer om ‘n ranglys van opsies te produseer in terme van tegniese effektiwiteit. Dit is voorgestel dat die top drie opsies verder ondersoek moet word. Die drie terminaal orientasie skemas, wat voorgestel word vir die Big Bay en Hoedjiespunt areas, maak gebruik van standaard jetties en drywende VNG tegnologie. Hierdie tesis bevind dat ‘n aantal uitvoerbare bouterreine en orientasies in Saldanhabaai moontlik is. ‘n Sistematiese analise van ontwerps kwessies wat na verkose opsies lei, word ook in die tesis ge-adresser. Die voorgestelde stappe in die besluitneming van ‘n finale terminaal skema vorm die slot van die tesis.