This thesis is concerned with the analysis of the main combustion products CO, CO2 and smoke from EVA nanocomposites, EVA and PVC cable materials under various ventilation conditions. Developed at Salford University this thesis describes attempts to improve and modify the Purser Furnace, by incorporation of a secondary oxidiser in order to facilitate the total carbon balance of the combustion, and a variable stepper motor to enable improved control over the fuel feed rate.

Urban particulate matter (UPM) is known to be a causative agent in a number of diseases including cancers of the respiratory system. Toxicological analysis has implicated particle size, surface area, metal ions, free radical induction, and organic chemistry as potential drivers of human health effects; however the relative importance of these factors is unclear. This project attempts to determine the factors responsible for the in vitro toxicity of particulate air pollution. The importance of fuel type on exhaust particle characteristics was examined through the collection of engine exhaust particles (EEP) produced by a heavy diesel engine operating using conventional diesel and rapeseed oil based biofuels. The effects of particle aging in the atmosphere, and the contributions of sources other than engine exhausts were determined through the collection of UPM from a roadside site. The genotoxic potential of particulate samples was determined using the comet assay, and particle free radical induction was measured with the plasmid strand break assay. Particle organic chemistry was determined using gas chromatography mass spectrometry. Particular emphasis was placed on the accurate quantification of polycyclic aromatic hydrocarbons (PAH), a class of carcinogenic hydrocarbons known to be present on the surface of particulate matter. Engine particulate samples were collected from a heavy duty diesel engine using conventional petrodiesel, rapeseed oil (RSa) or rapeseed oil with a fuel additive (RSaAd). Analysis of particulate specific emissions indicated that Rsa combustion generated a significantly greater mass of particulate matter than the combustion of diesel. This increase in particulate mass output was attributed to poor RSa combustion characteristics due to coking of fuel injectors during engine operation. ' This could be corrected through the use of a fuel additive, which bought Rsa particulate emissions into line with diesel. In all fuels the majority of the particulate mass collected had an aerodynamic diameter of less than one 1 urn, indicating that they may potentially deposit within the lower respiratory tract in humans, and as such are relevant to human health. Analysis of total suspended particle and size fractionated samples of engine particulate material showed that engine exhaust particles produced through diesel combustion were significantly more genotoxic than those produced whilst operating with biofuels. A statistically significant size dependency was found in diesel exhaust particles, with finer material inducing a greater level of DNA damage. Finer rapeseed oil exhaust particles were also shown to be more genotoxic than coarser material, although this trend was not as pronounced as in diesel exhaust particles, and was not statistically significant. Free radical analysis of exhaust particles showed that for all fuels the coarsest fraction of PM induced the largest level of radical activity. In most fractions diesel and Rsa EEP induced similar levels of damage, whereas coarse RSaAd induced significantly greater levels of free radicals. Free radical induction was indicated to be a result of particle phase metals present due to engine wear. Diesel EEP P AH levels were higher than Rsa or RSaAd samples in most size fractions of particles examined. Diesel EEP showed finer fractions to have the greatest P AH concentrations, with P AH concentration being roughly in line with v what might be expected based on projected surface area, suggesting absorption from the vapour phase as the mechanism by which P AH arrive on diesel PM. RSO and RSOAd EEP contained significantly lower P AH concentrations than diesel EEP. A correlation was found between particle phase P AH concentrations and observed DNA damage in the comet assay, suggesting PAH as potential drivers of genotoxicity. The concentration and distribution of n-alkane species was shown to be independent of fuel type, which is in line with previous studies that have indicated that engine lubricating oil is the major source of particle n-alkanes. Qualitative analysis of compounds other than P AH and n-alkanes in EEP showed differences in composition between diesel and RSO derived EEP, with the latter containing a greater number of oxygenated compounds. Size fractionated samples of UPM were collected from the Kirkstall Road air monitoring enclosure, located on a busy road servicing Leeds city centre. As in engine experiments the majority of particulate mass was found to be present in finer particles. In addition to particle size seasonal effects were observed with higher particle mass concentrations observed during colder sampling periods. Comet assay analysis of size fractionated UPM indicated that the majority of DNA damage was observed in the finest fraction of particles. However this damage was lower than that observed in the finest fraction of diesel EEP. In general particles collected during colder periods exhibited greater levels of DNA damage than those collected during warm sampling periods. As in diesel EEP the majority of the particle phase P AH detected were in the finest fractions of particulate material. Coarse UPM fractions contained a greater proportion of total particle phase P AH contributions than was observed in diesel EEP, possibly indicating particle agglomeration in the atmosphere. Additionally, a seasonal component was observed, with particles collected during colder seasons generally containing greater levels of PAH. A strong correlation between particle PAH concentrations and DNA damage in the comet assay was observed, indicating that the mechanism by which DNA damage occurs may involve PAH. Free radical analysis showed that the trend observed in EEP was reversed in UPM, with the finest fractions of UPM inducing greater levels of plasmid unwinding. This was at odds with the results of analysis of free radicals by EEP. The reason for this difference was unclear; however this may be a result of UPM and EEP inducing free radical activity by different mechanisms. The use of PAH diagnostic ratios and analysis of n-alkane species distribution indicated that the anthropogenic sources of particulate matter predominate at the roadside. There was evidence that UPM represented a more complex chemical mixture than EEP, with a greater number of particle bound organic compounds. The majority of these species were oxygenates, indicating oxidative processing of particles during atmospheric residence.

No description available.

It is well known that carbon dioxide (CO2) is a greenhouse gas that contributes to global warming. Nowadays, a third of the worldwide anthropogenic CO2 emissions arise from fossil fuel fired power production. Meanwhile, fossil fuels continue to be the main source of energy for the foreseeable future. The increasing threat posed by enhanced global warming, as well as the requirement for sustainable energy supplies around the world, have led to the development of several novel technologies to produce clean energy from fuels. Among these new technologies is chemical looping combustion (CLC) that uses a solid metal oxide (oxygen carrier) to react with fuels. This technology has the potential advantage that it produces a pure stream of CO2 that can then be sequestrated. In a CLC process, the oxygen carrier is reduced by fuels in one reactor while being oxidised by air in a separate reactor. As the oxygen carrier circulates through the system, it is subjected to morphological and compositional changes such as sintering, attrition and reactions between various metal oxides and fuels. These changes tend to cause the reactivity of the oxygen carrier to decrease over time. The main objective of this PhD study was to investigate and characterise the morphological and compositional changes of the oxygen carrier particles after they have undergone multiple reduction oxidation cycles in a CLC system. A single fluidised bed system was used in this study. Fuel was fed into a bed of oxygen carrier consisting of mechanically mixed iron oxide or wet impregnated copper oxide supported on alumina. The bed was fluidised by a stream of CO2 and/or steam. Pyrolysis gases from the fuel gasification process reduced the oxygen carrier while forming char in the bed. Thus char was oxidised and the oxygen carrier was regenerated when the fluidising gas was switched to air. Five different types of fuels were initially used in the tests. They were lignite coal, lignite char, activated carbon, US bituminous coal and Taldinski bituminous coal. The rates of gasification of the bituminous coal and activated carbon were much slower than those of the lignite coal and lignite char, resulting in an unfavourably large accumulation of char during the reduction stage. Subsequent experiments were conducted with UK bituminous coal to determine the effect of ash on the oxygen carrier particles over a long operational period. The series of analytical tests included; stereo microscopy, porosimetry analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy with an energy dispersive system (SEM/EDS) and Page ii X-ray photoelectron spectroscopy (XPS). Tests were performed on both the fresh and reacted oxygen carriers. Analytical results showed that when the pyrolysis gases react with the oxygen carrier, mineral matter left behind from the gasification process will deposit on the surface of the particles and diffuse into the core of the particles. This is due to the fact that mineral matter has a higher melting point compared to iron oxide and copper oxide. Iron oxide and copper oxide diffusing to the surface of the particles will replace those that are lost via attrition. As a result, the composition of the surface of these particles remains relatively unchanged. As more mineral matter diffuses into the core of the oxygen carrier particles, they can segregate metal oxide molecules located at the surfaces from those located at the core of the particles. When this occurs, there is a possibility that the segregated material formed will reduce the ability of oxygen to diffuse to the surface of the oxygen carrier particles. Hence this will reduce the conversion of the pyrolysis gases. This will thus lead to the reduction in the conversion of the pyrolysis gas and possibly in the deactivation of the oxygen carrier. It was found that the support structure played a key role in maintaining the structural integrity of the metal oxide particles during repeated reduction and oxidation cycles. Experimental results showed that the rate of attrition initially increases with time indicating that the oxygen carrier structure weakens as it interacts with the mineral matter in ash. Results from this research study have shown that the semi-batch chemical looping combustion of solid fuels is feasible provided reactive fuels that produce a large quantity of pyrolysis gases are used. Less reactive fuels will lead to the accumulation of a large inventory of char in the bed. The slow rate of gasification of char will then result in a lower carbon capture efficiency. In order to operate a semi-batch chemical looping combustion system with solid fuel, temperatures of above 1000°C are most likely required. However, this would exclude metal oxides with low melting points to act as potential oxygen carriers and may cause other problems such as ash fusion. A possible solution is to gasify the solid fuels in a separate reactor and channel the resulting pyrolysis gases into the chemical looping combustion system.

Calcium looping is a CO2 capture technology that is currently being developed on a 1 MWth pilot-scale. It has advantages including the ability to reclaim high-grade heat, the use of a relatively inexpensive, abundant and benign sorbent, and the potential to de-carbonise both power generation and cement manufacture. It makes use of the reversible carbonation of CaO to remove CO2 from a flue gas and provide pure CO2 for compression and storage, in a cyclical process. One aspect that is disadvantageous is the deactivation of CaO-sorbent upon cycling through reactive sintering; it is enhancement of sorbent that is examined here. Periodically hydrating sorbent, which can enhance sorbent performance by increasing reactive porosity, has been investigated: • Hydration conversion decreases following cycles of carbonation and calcination and at higher hydration temperatures. The latter has important consequences for the ability to reclaim high-grade heat from and reduce thermal cycling during the hydration process; • Particle breakage can occur upon hydration, which could be problematic for fluidised processes. This is more significant at lower hydration temperatures and for more highly sintered sorbents; • Direct carbonation of hydrated sorbent, rather than following a dehydration step, results in increased mechanical stability and increased reactivity to CO2; • Carbonation extent has an approximately linear relationship with prior hydration extent for equivalent carbonation methods; • A shrinking core model has been developed to describe the rate of reaction upon hydration. This successfully describes most data, but deviations are observed under conditions where pore blockage is likely. Enhancement of the performance of natural sorbent through surface doping with potassium compounds has also been investigated. KCl was found to enhance longterm conversion in the fluidised bed, with two mechanisms proposed: • Reduced friability of limestone, through KCl melt formation; • Increased carbonation rates in the slow solid-state diffusion phase.

No description available.

No description available.

Les poêles à pétrole sont des appareils de chauffage dépourvus d’évacuation des gaz brûlés vers l’extérieur de la pièce. Ils ont été à l’origine de 49 cas d’intoxication aiguë au monoxyde de carbone en France en 2007. Ce type de chauffage est aussi probablement responsable d’intoxications chroniques, mais celles-ci ne sont pas documentées. Cette thèse a pour objet la quantification en laboratoire des émissions gazeuses de poêles à pétrole récents et l’élaboration de protocoles de mesure pour l’étude de la qualité de l’air à l’intérieur de logements du Nord-Pas-de-Calais. Deux types de poêles à pétrole (à mèche et électronique) ont été étudiés dans une enceinte de 8 m3. Ils émettent principalement NO, NO2, CO, CO2 et des particules. Trois COV préoccupants (formaldéhyde, benzène et 1,3-butadiène) ont également été quantifiés. Les facteurs d’émission dépendent du type de poêle et de la composition du carburant utilisé, en particulier sa teneur en soufre, et en esters méthyliques d’acides gras dans le cas d’un carburant « bio ». L’accumulation de suies sur le poêle à mèche au cours de son utilisation s’accompagne d’une forte augmentation des émissions de CO, qui peut conduire à des intoxications chroniques et aiguës. Des mesures de terrain chez six volontaires ont permis de tester nos protocoles dans un milieu plus complexe que celui du laboratoire. Le rôle prépondérant des poêles à pétrole sur les niveaux de pollution dans les logements a été mis en évidence. Ce travail servira de base à une future étude épidémiologique portant sur la santé respiratoire des utilisateurs de tels appareils de chauffage. / Unvented kerosene space heaters were responsible for 49 cases of acute carbon monoxide poisoning in France in 2007. This kind of heater may also induce chronic intoxications, but no information on these is available. The aim of this work is the laboratory quantification of the gaseous emissions from recent models of kerosene space heaters and the preparation of an indoor air quality study in the Nord-Pas-de-Calais region. Two types of kerosene heaters (wick and injector) were tested in an 8 m3 instrumented environmental chamber. They emit mainly CO2, CO, NO, NO2, particles and some VOCs (especially formaldehyde, benzene, 1,3-butadiene). Emission factors depend upon the kind of heater and upon the type of fuel, and particularly on the fatty acid methyl esters and sulfur content. The accumulation of soot on the wick heater during use leads to a high increase of the CO emissions, and could be responsible for chronic and acute CO intoxications. Field measurements were undertaken to assess the effective exposure of users to pollutants emitted by kerosene space heaters in a complex environment. Kerosene space heater emissions were found to be the main source of pollution. This work will be applied to an epidemiological study on respiratory diseases caused by these heaters.

L’objectif de ce travail de thèse porte sur le stockage chimique du CO2 émis par l’industrie sidérurgique. Le processus de carbonatation directe de l’olivine et l’influence des conditions opératoires est évaluée afin d’optimiser le rendement de la réaction. Cependant, pour une acceptabilité environnementale et une rentabilité économique du projet, la récupération et la valorisation des produits de la carbonatation doivent toutes deux être considérées. La séparation des particules de chromite contenues dans l’olivine et inertes au cours de carbonatation, est tout d’abord étudiée par flottation en amont de la carbonatation. L’expérience de carbonatation montre qu’il est également possible d’extraire la chromite par séparation magnétique. Le rendement de carbonatation étant limité à 40 %, la séparation gravimétrique par sédimentation est alors envisagée pour récupérer les particules d’olivine résiduelle contenues dans les produits de la réaction, afin de les recycler dans le processus de carbonatation. Le tamisage des produits permet ensuite de concentrer les carbonates de métaux dans la fraction de particules de taille inférieure à 40 µm, tandis que la fraction comprise entre 40 et 106 µm contient davantage de silice. Cependant, la coprécipitation de carbonates mixtes liée à la présence de fer et de nickel inclus dans la matrice de magnésium compromet la purification et la valorisation optimale des produits de la carbonatation. De plus, la formation d’une couche de passivation en surface des particules limite la conversion de l’olivine. Un prétraitement de l’olivine est alors envisagé pour la lixiviation sélective du nickel en solution ammoniacale. Enfin, la carbonatation indirecte qui consiste en la dissolution préliminaire de l’olivine et la précipitation sélective des espèces avec un contrôle du pH de la solution se révèle être une alternative intéressante, imaginée pour l’augmentation du rendement de la carbonatation et l’obtention de produits de pureté satisfaisante / This work deals with the study of direct carbonation of olivine in solution, for the chemical transformation of CO2 emitted by the industries. The influence of operating conditions is evaluated in order to optimize the yield of the reaction. However, for environmental acceptability and economic viability of the project, the beneficiation of recoverable metals and products is considered. Chromite particles contained in olivine are unreactive during the carbonation reaction: the separation is developed by flotation upstream of the reaction. According to the results, the extraction of chromite by magnetic separation is also conceivable. Gravimetric separation by sedimentation is considered to recover residual olivine in the reaction products, in order to recycle them in the carbonation process. Products sieving allowed to concentrate carbonates (less than 40 µm) and silica (between 40 and 106 µm). However, the co-precipitation of mixed carbonates due to the presence of iron and nickel included in the magnesium matrix, compromises the purification and the optimal valorization of the solids. Moreover, the formation of a passivation layer on the particles surface limits the conversion of olivine. Pretreatment of olivine is envisaged for the leaching of nickel in ammoniac solution. Besides, preliminary dissolution of olivine and selective precipitation of species with pH control of the solution can be an interesting alternative for higher carbonation extent and more efficient purification of the products

Dans le cadre du développement des réacteurs nucléaires à neutrons rapides refroidis au sodium, des études sont menées sur les conséquences d’un feu de sodium, et sur l'impact toxicologique de rejets éventuels d’aérosols vers l’atmosphère. La carbonatation des aérosols issus d’un feu de sodium entraîne une diminution de leur toxicité, à partir de leur rejet sous forme d'hydroxyde de sodium (NaOH). L’objectif est de développer et de valider expérimentalement un modèle cinétique de carbonatation des aérosols de NaOH. L’adaptation d’un modèle cinétique basé sur l'absorption réactive du CO2 atmosphérique et par la théorie du double film permet de décrire la carbonatation des aérosols de NaOH, initialement sous forme de gouttelettes de soude. Ce modèle définit les caractéristiques initiales des aérosols de soude en équilibre avec l'atmosphère. Il a été appliqué en considérant l'absorption du CO2 à la surface externe des particules. L’ensemble des variables du modèle ont été décrites et leurs équations explicitées. La validation du modèle cinétique a motivé la mise en place d’un dispositif expérimental dédié au suivi du comportement chimique d’aérosols issus d’un feu de sodium, dans des conditions contrôlées d’atmosphère réactive et de prélèvement d’aérosols. L’exploitation des nouvelles données expérimentales montre la compétition entre l’influence de la température, de la pression partielle en eau et en CO2. La confrontation des résultats expérimentaux avec le modèle développé a permis de le valider pour des humidités relatives supérieures à 30%. Enfin, le modèle cinétique a été explicité sous la forme d’une expression analytique pour une utilisation associée aux calculs de dispersion atmosphérique. / As part of the development of 4th generation Sodium cooled Fast Reactors, studies are conducted on the consequences of a sodium fire, including the toxicological impact of possible releases of aerosols into the atmosphere. The carbonation of aerosols from a sodium fire results in a decreased toxicity, from their release point in sodium hydroxide (NaOH). The objective is to develop and experimentally validate a kinetics model of NaOH aerosols carbonation. The kinetic model based on the reactive absorption of atmospheric CO2 and using the double film theory enables to describe the carbonation of NaOH aerosols, initially formed as soda droplets. This model defines the initial aerosol characteristics of soda in equilibrium with the atmosphere. It is applied by considering the absorption of CO2 at the particle’s external surface. All the model variables are described and their equations explained. The validation of this kinetic model has motivated the development of an experimental device dedicated to the monitoring of physicochemical behavior of aerosols from a sodium fire with a better control of conditions of reactive atmosphere and of aerosols sampling. The new experimental data show the competition between the influence of temperature, partial pressure of water and of CO2. The comparison between the experimental results validates the kinetic model based on reactive absorption for relative humidity over 30%. Finally, the kinetic model was adapted into the form of an analytic expression for its use in association with the atmospheric dispersion calculation.