Dissertations / Theses: 'Pulverised fuel'

1

Yamanishi, Yoko. "Ignition behaviour of dried pulverised lignite fuel." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407180.

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2

Mahmud, Maythem Naji. "Utilisation of high carbon pulverised fuel ash." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11973/.

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Coal combustion by-products generated from coal-fired power plant and cause enormous problems for disposal unless a way can be found to utilize these by-products through resource recovery programs. The implementation of air act regulations to reduce NOx emission have resulted millions of tonnes of pulverised fuel ash (PFA) accumulated with high percentage of unburned carbon made it un-saleable for the cement industry. Moreover, alternative fuels such as biomass and import coals were suggested to reduce gas emissions but on the other hand PFA marketability was reduced. The main objective of this study was thus to utilise high carbon PFA into value added products. Through this work, the relationships beside the factors that could influence the carbon content in the PFA and reduce it in terms of producing raw material useful for different applications were explored. These factors were extensively investigated through thermogravimetric analyses, surface area measurements, microscopy and optical studies, and particle size distribution analyses. Five high unburned carbon PFAs were selected as feedstocks for PFA beneficiation, cement tests, and carbon activation. In order to beneficiate a high carbon PFA, incipient fluidisation was selected as the preferred route being a dry separation method which does not expose the carbon to potential contaminants that may alter its reactivity or physical properties. Enriched PFAs (i.e. depleted carbon) were separated and then cement tests were conducted in different mixture ratios (PFA/cement) throughout different time scales. These tests were demonstrated by using samples derived from biomass co-firing and import coals. The PFA/cement mixtures achieved good strength and workability via standard values. Unburned carbon (i.e. enriched carbon) streams were activated using steam at temperature 850 C and time from 60-300 minutes. For all unburned carbons investigated in this project, the surface areas of their activated counterparts increased to reach maximum level after three hours and four hours compared with other works. But this increase dropped back according to the reduction of the pore widening. Consequently, the surface area exhibited a high level of low carbon burn-out for the carbon sourced from biomass co-firing (1435 m2/g and 38 wt.%, respectively). This was revealed due to the carbon gasification and pore widening level. In addition, optical studies showed that the carbon types changed in a different manner during the activation.

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3

Cheng, Ruixue. "A study of electrostatic pulverised fuel meters." Thesis, Teesside University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262830.

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4

Groves, S. J. "Microstructure and properties of pulverised fuel slags." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38024.

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5

Ip, Mei-fong Phyllis, and 葉美芳. "Environmental management options for pulverised fuel ash (PFA)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31252849.

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Ip, Mei-fong Phyllis. "Environmental management options for pulverised fuel ash (PFA) /." [Hong Kong] : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13813535.

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7

Wain, Susan Elizabeth. "Thermal and mechanical properties of pulverised fuel boiler slags." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/8209.

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8

Cook, Simon Ernest. "Amendment of agricultural peat soils with pulverised fuel ash." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317763.

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9

Kirby, M. J. "Glass ceramics from a South African pulverised fuel ash." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/22118.

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Bibliography: pages 92-101.
The generation of electricity by the combustion of pulverised coal produces large quantities of coal ash (PF A). The disposal of this ash lias become a matter of concern due to the unsightly and hazardous nature of the PF A, and it has been the subject of intense investigations into its suitability as a raw material. Many uses have been proposed for the PF A. When used as landfill or mining backfill, the attraction is the low cost of the material. Other uses, as in the concrete industry, use PF A because of the improvements in quality of the resultant product. PF A has been suggested as a raw material for the production of wear resistant materials. The PF A is composed in the main of SiO₂ and AI₂O₃, and is a suitable material for the production of alumino-silicate ceramic materials, which are known to be tough and wear resistant. To establish the suitability of PF A from the Lethabo Power Station as a raw material, a project to prepare glass ceramic materials from the PF A was started. The conversion of the PF A to a glass ceramic material is a complex process involving many stages, and the processing at each stage will affects the final properties of the material. It is not possible in a short project such as this to examine all the factors which exert some control on the process, and so a small subset of these parameters was selected for study, namely the effect of added oxides on the crystallisation behaviour. Glass items which crystallise on holding at high temperatures commonly do so by growth of crystals from the surface of the item. This results in a material that is mechanically weak, due to the highly oriented microstructure that results. Nucleating agents can be used to obviate this. By providing sites for crystal growth in the bulk of the sample, they induce the crystallisation of fine grained ceramics with good mechanical properties. This study examines the effect of TiO₂, P₂O₅, and a mixture of iron and chrome oxides on the crystallisation of the glass prepared using PF A. The effect of these oxides was evaluated by examination of the microstructure of the crystalline specimens, and the kinetics of crystallisation were analysed by fitting data obtained by isothermal crystallisation of the specimens to the Avrami equation. Finally, the mechanical properties of the materials were tested by solid particle erosion, and the materials ranked against a selection of other materials used for their wear resistance.

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10

Tri, Utomo Suryo Hapsoro. "The effects of time on properties of pulverised fuel ash." Thesis, University of Newcastle upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307891.

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11

Dimitriou, Dimitrios. "Applied mathematical modelling of NO abatement in pulverised fuel furnaces." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409410.

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12

Muhammad, Musib Siddique. "The prediction of ash deposition in pulverised fuel fired combusters." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398837.

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13

Clark, Kevin David. "Toxic metal and NOx emissions from pulverised solid fuel combustion." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413705.

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14

Chanda, S. "The mechanical properties of a pulverised fuel ash blended cement paste." Thesis, University of Surrey, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370690.

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15

Woolley, G. R. "A study of the characteristics of heat of hydration of PFA concrete in thin structures." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305566.

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16

Byars, Ewan Alexander. "PFA concrete : strength development and permeation properties." Thesis, University of Dundee, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343527.

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17

Shah, Zahid Hussain Syed. "The development of visual based flame monitoring techniques for pulverised fuel fired boilers." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408864.

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18

Carroll, Robert A. "Hydrothermal performance of pulverised fuel ash and the manufacture of autoclaved aerated concrete." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/7321.

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Pulverised fuel ash (PFA) is a reactive silica source used in the manufacture of autoclaved aerated concrete (AAC). Experiments studied the hydrothermal reactions of PFA samples from two UK power stations with calcium hydroxide at 457 K, for periods up to 21 h. These conditions are comparable to those used in the manufacture of AAC. The process is characterised by the rapid consumption of ash particles. Associated with this is the solubilisation of large amounts of silica, alumina and alkalis. The formation of a semi-crystalline calcium silicate hydrate and a hydrogarnet phase occurs during the early stages of autoclaving. The hydrogarnet phase persists under the conditions studied, but conversion of the calcium silicate hydrate into tobermorite occurs with prolonged autoclaving. Differences in the hydrothermal performance of the two PFA samples are evident, which cannot be explained by the bulk elemental composition. Ash fractions obtained from a centrifugal air classifier have different reactivities during autoclaving and can result in specimens with different compressive strengths. Quantitative x-ray diffractometry showed that high levels of aluminosilicate glass are associated with the fine ash fractions, whereas most quartz, haematite and magnetite is associated with the coarse fractions. Significant differences exist in the mineralogical analyses of the two sets of ash fractions obtained from the bulk ash samples. The coarse ash fractions have the most varied morphology and composition.

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19

Masanja, Enock. "Study of particle motion in flows characteristic to low-NOx pulverised fuel burners." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/17027.

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There is no dispute that combustion by-products like sulphur dioxide, SO₂ and nitrogen oxides, NO_x, can cause environmental damage. New, tougher legislation on gas emission has started to push fundamental research work (like this project) on understanding particle/fluid dynamics in combustion and related systems to the fore front. The knowledge gained will not only offer immediate help in the control and abatement of gas emission, but also the data obtained will complement the available empirical (industrial) knowledge of roping behaviour which will be valuable in developing new numerical models and/or verifying existing ones. A test facility delivering up to 40 m/s in a 4 inch glass test section was designed, fabricated, assembled and tested. This includes swirl generators for generating swirl of 0.2 to 1.35 theoretical swirl numbers. The facility also includes a particle feed section, cyclone separator for recovering the particles and a dual pulsed Nd:YaG laser, related optics and other equipment for use in future Particle Image Velocimetry (PIV) research. LDA and Pitot-static measurements verified that the test section was capable of delivering the planned/design velocity measurement range of 0-40 m/s. PIV experiments were done for particle jet density of 95 kg/m_-3 to 198 kg/m_-3 and the results obtained on particle jet dispersion were in good agreement with previous work showing that the centre line velocity showed less fluctuation and that jets that are less dense disperse more than the denser ones.

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20

Larsen, Kristofer Jon. "Pulverised biomass and coal co-firing simulation using computational fluid dynamics : a numerical investigation into the aerodynamics of non-spherical particles and full scale combustion for pulverised fuel applications." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/3138/.

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Recent national and international emissions legislation, in particular sulphur-dioxide, and the rapid depletion of fossil fuels are forcing power producing industries to look at various alternatives, such as biomass and co-firing techniques. Biomass may be transported to the burners of a pulverised fuel (PF) boiler either mixed with the primary fuel, in general coal, or used in dedicated pipelines. In both cases, the transportation of biomass is different due to its composition, size and shape to the transportation of coal. This thesis investigates the computational modelling techniques for a biomass and biomass blend particle transportation (arboreal and flour) in a pipeline with a transverse elbow, the three-phase flow of a coal and biomass co-fire blend in the primary air annulus of a swirl burner and the combustion of a coal and pelletised straw mixture in a full scale furnace using dedicated burners for the biomass injection. The comparison of spherical and non-spherical drag models, under gravity, as well as Saffman lift, inter-particle collision and randomised impulsive wall collision models has been investigated. Good agreement was observed between the computational fluid dynamics (CFD) simulations and the experimental data, using a non-spherical drag model. In both cases, due to the dilute volume fraction and secondary air flow, inter-particle collisions and lift were insignificant. In the annulus, lateral regions of high particle concentration were predicted, which are not observed physically. Numerical simulations of a 300MWe tangentially fired furnace, co-firing bituminous coal and pelletised straw, have been performed and compared to experimental data. Bituminous coal was co-fired with pelletised straw. Good agreement was obtained between the CFD predictions and the experimental data so that the trends of furnace temperature, NOx emissions and carbon burnout reduction, as biomass load is increased, were observed. Quantitative prediction of unburnt carbon (UBC) and NOx require a more detailed picture of the processes within the furnace at higher temperatures than that currently provided by experimental data.

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21

Lee, Sanghoon. "The long-term weathering of pulverised fuel ash and its implications for groundwater pollution." Thesis, University of Sheffield, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299821.

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22

Yang, Yunlai. "Study of the mechanical properties of pulverised fuel ash for use in geotechnical applications." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386970.

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23

Awe, Yewande Aramide. "An investigation of the use of two industrial waste by-products in contaminant barrier systems." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321928.

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24

Bridge, Christopher P. "Biomass co-firing to improve the burn-out of unreactive coals in pulverised fuel combustion." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50550/.

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Biomass utilisation as a fuel in power generation has become an increasingly attractive prospect due to legislation and consumer awareness surrounding fossil fuels and their effect on climate change. However, a large portion of the world relies upon energy produced from readily available local coal sources. Large quantities of these local coals have low combustion efficiencies and energy outputs. An investigation was conducted to improve the combustion performance of these unreactive coals through the addition of small quantities of biomass in co-fired pulverised fuel conditions. To assess whether unreactive coal co-fired with biomass produced improved combustion performance a study of slow heating interactions was undertaken. Through the use of laboratory thermal conversion techniques, thermogravimetric analysis and horizontal tube furnace, slow heating ramp rates were achieved. Samples blended on a 50% coal loading experienced these conditions. Slow heating pyrolysis on a 50% coal loading displayed no synergistic improvement to VM content of coal blended with biomass, whilst catalytic increases of char reactivity were observed for coal blended with high ash biomass species through burn-out testing, such as OC. Following the baseline observations for slow heating conditions, blended samples were subjected to fast heating ramp rate conditions, through the use of a drop tube furnace. At fast heating pyrolysis conditions on a 50% coal loading synergistic improvements of VM yield were observed for coal blends with low ash biomass species, such as W. High ash biomass species showed minimal evidence of synergetic increase to VM, instead displaying the catalytic improvements to char burn-out performance, as seen with slow heating rates. A trail of varying coal loading ratios was conducted to determine the quantity of biomass required to observe the greatest improvements and to ascertain the viability of findings at industrially relevant conditions. Synergistic improvements in VM yield were caused by a steam gasification mechanism during fast heating ramp rates whilst catalytic improvements were caused by the presence of high quantities of alkali and alkaline earth metals (AAEMs). Fast heating rate coal blend trials conducted with partially demineralised biomass fuels provided a deeper understanding of the influence that AAEMs had on char reactivity. A regression analysis provided a quadratic model that demonstrated a strong relationship between AAEMs and char reactivity, with a correlation coefficient R2 value in excess of 95%. A fast heating rate combustion test was conducted to determine whether improvement to ignition distance could be achieved through co-firing. Both qualitative and semi-quantitative analysis of the captured particle images were inconclusive as to improvements in ignition distance.

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25

Perkins, Paul. "The amelioration of acidic minespoil with pulverised fuel ash with particular reference to the fate of boron." Thesis, University of Huddersfield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295997.

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26

Bosch, Gordon L. "The mineralogy and chemistry of pulverised fuel ash produced by three South African coal-burning power stations." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/22044.

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Bibliography: pages 161-166.
The chemical and mineral compositions are presented for 63 pulverized fuel ash (PFA) and 16 input coal samples collected from Lethabo, Duvha and Matla power stations over the period 1987-1988. Bulk chemical composition was determined by X-ray fluorescence spectrometry. The mineral concentrations were determined by semi-quantitative X-ray diffraction based on integrated counts over peak areas, with silicon used as an internal standard. The particle size distributions were determined for two sample sets from each power station with a Malvern Instruments Particle Sizer. The major phases present in the ash are glass ( 45-75% ), mullite (16-39%) and quartz (1.5-16% ). The quartz concentration decreases in PF A from fields 1 to 4 in all the stations, and is positively correlated with the SiO₂ concentration. The concentrations of glass, mullite and quartz in PFA generally vary within well defined limits which remain constant with time. An exception is the glass concentration in Duvha PFA. Spinel concentration generally decreases in concentration in PFA from fields 1 to 4, and is positively correlated with the Fe₂O₃ concentration. Of the trace elements determined, Zr, Rb and Mn generally have no or very low enrichment in concentration in PFA from fields 1 to 4. The highest enrichment factors ( > 5) were found for As, Ge and Se in Duvha PF A. The composition of the glass and ferrite spinel phases were determined by electron microprobe analysis. The glass consists of SiO₂ (21-100%) and Al₂ O₃ (0.1-49%), with significant proportions of CaO, TiO₂, Fe₂O₃ and MgO. Al₂O₃ , MgO and TiO₂ substitute for FeO in the spinel structure, with MgO substitution dominant in Duvha spinels. Chemical mass balance calculations suggest that of the elements determined for Lethabo PFA, the only one released in a significant proportion to the atmosphere is S(92% ).

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27

Mason, Patrick Edward. "On the combustion of solid biomass fuels for large scale power generation : investigations on the combustion behaviour of single particles of pulverised biomass fuel." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15490/.

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Biomass is classed as a renewable resource. Depending on the means of production, it can be sustainable and can provide net benefits regarding CO2 emissions by displacing fossil fuels as an energy source. A significant biomass energy conversion technology is combustion in conventional thermal power stations. This can be implemented in large scale plants such as those which dominated electricity generation throughout the 20th century. While these power stations were generally fuelled by the erstwhile ‘King Coal’, the technology is not exclusive to it. Coal consumption can be displaced in these types of plants by either co-firing biomass with coal or full conversion to biomass. Currently, in the UK, the vast majority of the biomass fuel consumed for power generation is imported pelletized forestry wood. However, sustainability and domestic energy security concerns have created interest in using other resources including energy crops such as short rotation coppice willow and miscanthus, agricultural by-products such as wheat straw and olive residue. The variation in the properties of these fuels presents a number of technical challenges which conventional power plant must overcome to achieve ‘fuel flexibility’. Along with other technical challenges regarding the operation of conventional thermal power plant, these formed the basis of the Research Councils UK funded consortium grant (EPSRC, 2012) entitled Future Conventional Power. As a consortium partner in this project, the University of Leeds led research tasks associated with fuel flexibility. Much of the research presented in this thesis was based on the objectives set out in the Future Conventional Power project and was financially supported though this grant. Two particular challenges provide the incentive for the investigations presented in this thesis and can be summarised as: • assessing the variability in fuel combustion behaviour and control of burn-out efficiency for different fuels • understanding the behaviour of potassium during the combustion of biomass fuels to aid in the prediction of ash behaviour, emissions and associated operational problems Both these points were addressed with a series of experimental studies. In addition, a model of the combustion of single particles was developed for validating and interpreting the results. A range of fourteen solid biomass fuels, typical of those likely to be used in large scale power plant, were selected for the experimental studies. The composition and fundamental characteristics of these fuels, obtained by standard analytical techniques, are presented. In the first experimental study, single particles were exposed to a methane flame, simulating biomass combustion in a furnace. Measurements of ignition delay, volatile burning time and char burn-out time were undertaken using high speed image capture. Particle surface temperatures were measured by infra-red thermal imaging. Analysis of the data identified correlations between the biomass fundamental characteristics, particle size, and the observed combustion profiles. Empirical expressions for the duration of each combustion stage are obtained from the data. From these, a “burn-out” index is derived which provides a useful indication of the relative milling requirements of different fuels for achieving effective burn-out efficiency. A similar experimental method was used in the second study in which the gas-phase potassium release patterns from single particles of various biomass fuels were measured by use of flame emission spectroscopy. The observed potassium release patterns for the various fuel samples are presented. The release patterns revealed qualitative differences between different fuel types. Relationships between the initial potassium content, peak rate of release and the fractions of potassium released at each stage of combustion were identified. These were subsequently used for comparing with results of modelled potassium release. A third experimental study investigated the variation in thermal conductivity between different types of solid biomass using a technique and apparatus developed specifically for the study. The results showed variation of thermal conductivity between different types of biomass which had been similarly homogenised and densified. The thermal conductivity of small particles of each fuel was derived. The resulting data provides useful values for thermal modelling of biomass particles and is used subsequently in a combustion model. Elements of each of the experimental studies were used in a detailed model of single particle combustion. In this, the particle was modelled as a series of concentric spherical layers which enabled calculation of internal mass diffusion and heat transfer. Devolatilisation and char oxidation were approximated with single step reaction kinetics. A volatilisation and diffusion mechanism was adopted to simulate the release of gas-phase potassium from the particle. The output from the model was compared and validated using data from the experimental studies. The modelling produced confirming evidence that the assumed mechanisms for gas-phase potassium release were valid and provided a tool for future investigation of the subject.

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28

Duddy, Margaret Mary. "An investigation into the suppression of the alkali-silica reaction in concrete by the use of pulverised fuel ash." Thesis, University of Hertfordshire, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260799.

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29

Birchall, Colin. "An examination of the fired properties and characteristics of an incinerated sewage sludge ash/pulverised fuel ash composite tile body." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339244.

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30

Zaidi, Syed Azhar Mehdi. "The control of combustion and pollutant emissions of pulverised fuel flames through the implementation of fuzzy logic based embedded reasoning." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398941.

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31

Ganaw, Abdelhamed I. "Rheology of grout for preplaced aggregate concrete : investigation on the effect of different materials on the rheology of Portland cement based grouts and their role in the production of preplaced aggregate concrete." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5766.

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Preplaced aggregate concrete (PAC) is produced by grouting high workability cement based grouts among the voids of compacted coarse aggregate mass. Because of its low shrinkage, PAC has been used for many repair jobs like; tunnel lines, dams and bridge piers. Moreover, it has been used for underwater construction. Grout has a major effect on the properties of produced PAC and well defined grout controls the properties of resulted PAC. The effect of types and amount of powder materials, admixtures, sand and water content on the properties of fresh and hardened grout for the production of PAC have been investigated. Tests on hardened grout and PAC properties have also been carried out to investigate the most important effects. A correlation between hardened properties of grout and PAC has also been analyzed. Grout rheology using four different gradation sands at two different cement-sand and at different w/c ratios ratios has been identified experimentally; no added chemical admixtures or mineral additives had first employed, then superplasticizer (SP) was added at 2% and 1%, and finally a combination of 1% SP and pulverized fuel ash (Pfa) at 20% of the cement weight was employed for all mixes. Grout tests have included two point workability tests by the Viskomat NT, flow time funnel test, Colcrete flow meter test, and water bleeding test. After that, eighteen grout mixes with high workability were produced using three different sands at three w/c ratios and two c/s ratios with 1% SP and Pfa at 20% of the cement weight were designed. Eighteen hardened grout and PAC then produced and their compressive strength and sorptivity were tested. Grout rheology can be defined by the rheology of cement paste employed and the internal distance between sand particles. The effect of sand surface texture on grout rheology is important at very low internal distances. Fresh grout yield stress is the most important property which gives the same degree of sensitivity for all grouts regardless the material type and content used in the mix. There are strong relations between compressive strength of grout and PAC, but less correlation between them in sorptivity test because of the effect high quantity of coarse aggregate of PAC. Sorptivity of PAC is low comparing with different kinds of concrete suggesting its advantage for underwater construction.

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32

Okoronkwo, Chijioke David. "Developing sustainable and environmentally friendly building materials in rammed earth construction." Thesis, University of Wolverhampton, 2015. http://hdl.handle.net/2436/612020.

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Building rammed earth structures provides a sustainable alternative to concrete. As a building material, rammed earth exhibits very varied physical and material properties depending on the proportion of constituting soil types. When very sandy soil is used in rammed earth production, the properties are different from when a clayey soil is used. This variability can be seen as a very great advantage in the use of rammed earth as a building material. Builders are able to adjust specific properties by changing mix proportions to obtain a desirable balance in the characteristics of the resulting rammed earth structure. This research work looks at selected mechanical and physical properties of different mixes of rammed earth. It describes typical range of values in density, thermal conductivity, ultrasonic pulse velocity, water ingress and compressive strength. It examines how these factors interrelate in the same soil mixes. Samples were prepared by blending various soil types in specific proportions to ensure that each definition of soil grade is as specific as possible. Unstabilised rammed earth was tested as was cement stabilised rammed earth. Rammed earth was tested at various levels of stabilisation and it was discovered that higher rates of stabilisation was not always beneficial to every material property. The research also looked into the potential disposal of waste materials in rammed earth. As rammed earth is a monolithic material that largely remains undisturbed throughout its life span, it was suggested that waste materials could be stored in an inert form inside of rammed earth rather than dumping it in otherwise agricultural landmass. Pulverised Fuel Ash and Palm Kernel Shells were identified as wastes to be disposed in rammed earth. Pulverised Fuel Ash, a by-product of industrial furnace is found in abundance in developed countries that burn carbonaceous materials in power plants. Disposals have been seen as a problem as only a small proportion of high loss on ignition (LOI) Pulverised Fuel Ash has found application. Palm Kernel Shell is a by-product of the oil palm industry and is currently a menace in many developing countries that need to dispose large quantities of the shell in landfills. At an early stage of the research, experimental trial runs quickly showed that these supposedly waste materials had a positive effect on some of the material properties of the rammed earth walls they were made into. This research effort evolved to look into exploiting these materials to improve the physical and material property of rammed earth and to suggest their effect on stabilised and unstabilised rammed earth. The extent to which these materials could be useful and the level at which diminishing returns set in was also investigated. It was discovered that soil mixes that would otherwise not be considered suitable for use in rammed earth wall production can now be utilised as their characteristics can be improved on simply by adding Pulverised Fuel Ash or Palm Kernel shell in the right proportion. Incorporating Pulverised Fuel Ash in rammed earth resulted in increased compressive strength. Palm Kernel shell improved thermal properties without compromising compressive strength.

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33

Tinkham, Kevin Michael. "Surface studies of pulverized fuel ash." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278875.

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34

Ndibe, Collins [Verfasser]. "Characterization of torrefied fuels for direct co-firing in large pulverized fuel boilers / Collins Ndibe." Düren : Shaker, 2019. http://d-nb.info/1190525763/34.

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35

Ismail, Mostafa Mostafa Ahmed. "Char burn-out and flame stability in a pulverized fuel furnace." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47486.

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36

Bose, Arun Chand. "Pulverized coal combustion: Fuel nitrogen mechanisms in the rich post-flame." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184635.

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Chemical kinetic mechanisms governing the fate of coal nitrogen in the fuel-rich stage of a pulverized-coal staged combustion process were investigated. Emphasis was on determination of the effects of coal rank, temperature and stoichiometric ratios on the speciation and rates of destruction of nitrogenous species and correlation of coal data by a unif1ed mechanism. The relative importance of homogeneous and heterogeneous mechanisms during post-flame interconversion reactions of the fuel nitrogen pool was quantified. Experiments with doped propane gas and a high- and low-grade coals, burned under a variety of conditions in a 2 Kg/h downflow combustor, yielded timeresolved profiles of temperature, major (H₂, CO, CO₂, O₂ and N₂), nitrogenous (NO, HeN and NH₃) and hydrocarbon (CH₄ and C₂H₂) species. These profiles allowed global mechanisms describing the speciation and destruction of fuel nitrogen species to be explored, using predictive models of increasing levels of sophistication. Fuel nitrogen speciation varied significantly from coal to coal and depended on stoichiometric ratio and temperature, which were varied independently. A general correlation describing the destruction rate of NO was derived from data. This rate, which was first-order in both NO and NH₃, was generally valid for all coals and all conditions examined. Fuel nitrogen interconversion reactions, especially destruction of NO and HeN, was predominantly homogeneous, but no single elementary reaction was controlling. Temperature quench down the combustor is the origin of OH equilibrium overshoot. Expressions for estimating the OH equilibrium overshoot as a function of the axial temperature decay along the combustor were derived both empirically and kinetically from fundamental considerations using data from doped propane gas runs. These expressions, together with available literature values of gas phase rate coefficients, could adequately describe the post-flame NO and HeN profiles of coal and gas runs. HeN profiles in the far postflame zone of the coal flames are strongly influenced by the slow release of nitrogen from the coal residue. This devolatilization plays a critical role in supplying the HeN that drives the multistep process converting fuel N into molecular nitrogen.

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37

Jankoski, Zlatko. "Observing and enhancing the controlled ignition of pulverised solid fuels." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428490.

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Ou, Jenq-Jang. "The combustion of fossil and waste solid fuels." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308074.

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Salem, Mahmoud. "Investigation of materials based on pulverized fuel ash and sodium silicate solutions." Thesis, University of Greenwich, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303855.

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Mackrory, Andrew John. "A Mechanistic Investigation of Nitrogen Evolution in Pulverized Coal Oxy-Fuel Combustion." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2640.pdf.

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Harrison, Paul James. "Measurement of specific VOCs from combustion of pulverised fossil and renewable fuels." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399342.

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42

Chan, Kwok-wong, and 陳國煌. "The study of utilization of pulverized fuel ash in road construction in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31232966.

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Smith, Karl M. "The capture of COâ‚‚ from flue gas using adsorbents developed from pulverized fuel ash." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440998.

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Chan, Kwok-wong. "The study of utilization of pulverized fuel ash in road construction in Hong Kong /." [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1339244X.

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Shen, Qiqing. "Rapid Pyrolysis of Raw and Pretreated Biomass under Conditions Pertinent to Pulverized Fuel Applications." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/86933.

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This Ph.D. study investigates the rapid pyrolysis of biomass at high temperatures and the properties of derived char samples under various conditions. A novel drop-tube furnace was used to experimentally determine the accurate char yields after rapid pyrolysis at 1300°C, which is realized for the first time. Based on true char yield, the evolution of char properties was revealed, and the retention of inorganic species, the transformation of particle shape during rapid pyrolysis were quantified.

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Baranski, Jacek. "Physical and numerical modelling of flow pattern and combustion process in pulverized fuel fired boiler." Licentiate thesis, KTH, Materials Science and Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1533.

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This licentiate thesis describes development of modellingtools, experimental physical modelling and numerical modellingto simulate real combustion processes for advanced industrialutility boiler before and after retrofit.

The work presents extended study about formation,destruction and control of pollutants, especially NOx, whichoccur during combustion process.

The main aim of this work is to improve mixing process incombustion chamber. To do this, the optimization of placementand direction of additional air and fuel nozzles, the physicalmodelling technique is used. By using that method, it ispossible to obtain qualitative information about processes,which occur in the real boiler. The numerical simulationsverify the results from physical modelling, because duringmathematical modelling quantitative informations about flow andmixing patterns, temperature field, species concentration areobtained.

Two 3D cases, before and after retrofit, of pulverized fuelfired boiler at 125 MW output thermal power are simulated. Theunstructured mesh technique is also used to discretize theboiler. The number of grid was 427 656 before retrofit and 513362 after retrofit. The comparisons of results of numericalsimulation before and after retrofit are presented. The resultsfrom physical modelling and numerical simulation are alsoshown.

Results present that nozzles of additional air and fuel givea considerably better mixing process, uniform temperature fieldand CO2 mass fraction. The whole combustion chamber worksalmost as a "well stirred reactor", while upper part of boilerworks as a "plug flow reactor".

Differences between from measured of temperatures andpredicted temperatures are not too big, the maximum differenceis about 100 K. It seems, that calculated temperatures showgood agreement with measurement data.

The results illuminate the potential of physical andnumerical modelling methods as promising tools to deal with thecomplicated combustion processes, even for practicalapplication in the industry.

Keywords:air staging, fuel staging, boiler, furnace,computational fluid dynamics, numerical simulation, pollutants,physical modeling, pulverized fuel combustion.

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Kleinhans, Ulrich Sebastian [Verfasser]. "Fly Ash Formation and Deposition during Pulverized Fuel Combustion: Numerical and Experimental Investigations / Ulrich Sebastian Kleinhans." München : Verlag Dr. Hut, 2017. http://d-nb.info/1135596417/34.

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Ngai, Yuen-yi Helen, and 魏婉儀. "Soil genesis and vegetation growth in pulverized fuel ash and refuse landfills capped by decomposed granite." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31219780.

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Ngai, Yuen-yi Helen. "Soil genesis and vegetation growth in pulverized fuel ash and refuse landfills capped by decomposed granite /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19471166.

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Stimpson, Curtis K. "The Composition and Morphology of Coal Ash Deposits Collected in an Oxy-Fuel, Pulverized Coal Reactor." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3225.

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Coal ash deposits were collected in a 160 kWth, down-fired oxy-coal reactor under staged and unstaged conditions for four different coals (PRB, Gatling, Illinois #6, and Mahoning). Concentration measurements of carbon, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, chromium, manganese, iron, nickel, strontium, and barium were gathered from each deposit sample using scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Backscattered electron micrographs for each deposit sample were analyzed to gather morphological data. Particle size and shape were studied for each deposit collected. The average particle sizes of the particles in upstream deposits were much larger than the average particle sizes of the downstream deposits. The downstream deposits consisted primarily of spherical particles while the upstream deposits consisted of round, irregular polygonal, and porous particles. Deposit particles are believed to have deposited at all stages of burnout; those depositing early during pyrolysis may have continued to react after deposition. Element maps for the aforementioned elements were collected with SEM-EDS and analyzed to quantify both average composition and composition of individual particles. These values were compared to ASTM ash analyses performed for each coal and ash collected from the flue gas stream with a cyclonic particle separator. It was found that sulfur concentrations of deposits do not correlate with corresponding sulfur concentrations of the coal. Comparison of similar experiments performed with air-combustion show that oxy-combustion deposits contain about twice as much sulfur as air-combustion deposits when burning the same coal. Deposition propensity of each coal was also examined, and the PRB and Gatling coals were found to have a moderately high deposition propensity whereas the deposition propensity of the Mahoning and Illinois #6 coals was fairly low.

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Dissertations / Theses on the topic 'Pulverised fuel'

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