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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Hydrogenation of naphthalene and coal tar distillate over Ni/Mo/Al₂O₃ catalyst in a trickle bed reactor

Bhagavatula, Abhijit. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xii, 119 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 114-119).
32

Förekomst och urlakning av PAH längs med väg 805, Jokkmokks kommun

Blom, Maria January 2018 (has links)
The purpose of this study was to determine if any amount of PAH (Polycyclic aromatic hydrocarbons) was leaching from the paved road surface of road 805 in Jokkmokk municipality. The study was also meant to determine which factors affected the leaching of PAH in the studied area.The surveyed road was divided into eight sections. Groundwater pipes were inserted into drilled holes, three in each section. Samples from soil, water and asphalt were collected from each section and analyzed for its content of PAH. The groundwater level was measured before each sampling. Some soil samples were analyzed for TOC (total organic carbon) and all the water samples for DOC (dissolved organic carbon). The results showed that PAH was leaching in very different amounts. There was a similarity in the amount of coal tar in the road surface and the amount of PAH in most sections. Although in one section the asphalt sample showed low amount of coal tar but high amount of PAH in the soil- and water samples. This anomaly could not be explained - the assumption was that the sampling had been incorrectly handled. The pollution in the surveyed area is assumed to be caused by the road surface and tire wear. Further studies are necessary to determine with certainty how PAH is leaching in different conditions and with different road pavements.
33

Investigation of thermal biomass gasification for sustainable small scale rural electricity generation in Uganda

Olwa, Joseph January 2011 (has links)
With the increasing need for renewable energy technologies in the world, biomass fuel transformation technology is growing towards meeting that need, among others. Challenges remain certain and new innovations are being tested in bid to overcome them with the application of biomass as energy source. This report presents some studies carried out into understanding the potential and challenges associated with utilization of biomass fuel, especially for technologies that are appropriate for rural applications.  Utilization of biomass gasification technologies is in the focus of this study.   The great potential biomass fuel provide to Uganda for possible energy production in small scale application is presented. This study was carried out to understand the possibility of using biomass as fuel in electricity power generation in Uganda. It takes into consideration the use of biomass gasification technology in energy production. Challenges related to the application of biomass fuels are discussed, mostly with tar and alkali metal compounds in the gas stream.   Suggested methods to combat some of the challenges with biomass fuels are pointed out in this study. Application of externally fired gas turbine (EFGT) system is a particular approach discussed and its technical performance analyzed.  The analysis revealed that efficiency of the EFGT system is greatly dependent on the heat exchanger effectiveness and on turbine inlet temperature. Optimum performance can be realized with air compression ratio of 3.4. It is also noted that fouling and deposition in the heat exchanger can affect its performance.   A related study carried out was on the retention of alkali metals in an updraft gasifier. The gasifier was chosen for possible integration with the EFGT system. Finding was that about 99% of the alkali metals are retained in the gasifier. It is anticipated that this would reduce on the deposition in the heat exchanger, reducing on maintenance time. A need is identified to determine the level of deposition mentioned. A simple thermodynamic modeling of the alkali metals condensation reaction on a high temperature heat exchanger surface was conducted. The results showed that with appropriate quantity of S in the raw fuel, alkali metals bounding with Cl are greatly reduced. Cl is passed out as gaseous HCl, leaving deposition of none corrosive sulphates. Recommendation is made to study this phenomenon in an experimental setting.   Biomass gasification technology integration with an internal combustion (IC) engine is also studied. Here requirements for the producer gas quality have been discussed. Some tests carried out with wood pellets and wood cylinders compared the yield of tar from the two physically different fuels.  Wood pellets were found to yield more tar than wood cylinders.   Economic analysis of biomass gasifier integrated with an IC engine running a generator of 100 kWe was carried out. Comparison with a diesel electricity generator of similar capacity was made for a scenario in Uganda over a project life of 20 years. Different Plant Capacity Factors (PCF) and fuel costs including subsidies were considered. The analysis showed that over long period of time biomass power plant was more beneficial than the diesel power plant at PCF over 40%. This is more pronounced with unsubsidized diesel fuel. / QC 20111206
34

Biomass Gasification: Catalytic Steam Reforming of Tars Using Nickel Supported Zeolites and Montmorillonite

Buchireddy, Prashanth R 17 May 2014 (has links)
Tars have been identified as one of the major impurities associated with the utilization of biomass gasification fuel gas. Tars may result in blockages, plugging, corrosion and catalyst deactivation, leading to serious operational and maintenance problems during biomass gasification. Therefore, tar removal is essential to insure economic and effective fuel gas utilization. This study investigates the catalytic activity of zeolites, and nickel-supported zeolites for tar removal. Tests were conducted using a bench scale reactor and naphthalene as a model tar compound. Zeolites with varying pore sizes and acidity were tested to evaluate the effect of pore size and acidity on tar removal. Test results suggested that the catalytic activity increased with an increase in pore size and the number of acidic sites on the zeolite. The steam reforming ability of nickel towards naphthalene removal was evaluated by impregnating nickel on zeolites; this impregnation improved the activity of the catalysts significantly. Long term catalytic activity tests were performed, which showed that nickel supported ZY-30 and ZY-80 had the best naphthalene conversion, with naphthalene conversions of greater than 99%, followed by nickel- supported ZY-5.2, SiO2/Al2O3, and chabazite, respectively. This study also evaluated the catalytic activity of montmorillonite and nickel- supported montmorillonite as tar removal catalysts. Montmorillonite, and Ni-montmorillonite were tested for their efficiency in reforming tars. Also, the efficacy of nickel-supported montmorillonite catalyst was tested as a function of nickel content, reaction temperature, naphthalene loading, and the steam to carbon ratio. The results demonstrated that montmorillonite was catalytically active in removing naphthalene. In addition, Ni-montmorillonite had very high activity towards naphthalene removal via steam reforming, with removal efficiencies of greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first order kinetics and was found to be 84.5 kJ/mole. Long-term activity tests showed that the catalyst was active with naphthalene removal efficiencies of greater than 95%, which were maintained over a 97-hour test period. Very little loss of activity was observed with a drop in removal from 97 to 95%. The drop in catalytic activity was attributed primarily to a decrease in catalyst surface area, nickel sintering, and coke formation.
35

The synthesis of 10-(4-hydroxymethylphenyl)-1,2-Benzanthracene

Lewis, Claude Irenius January 1959 (has links)
A. The alcohol, 10-(4’-hydroxymethylphenyl)-1,2-benzanthracene, was prepared by the reduction or 10-(4’-carboxyphenyl)- 1,2- benzanthracene. The structure or the alcohol was proven by: (1) Ultraviolet spectra (2) Infrared spectra (3) Elementary analysis (4) Preparation or the benzoate B. The preparation of the Grignard reagent of 10-(4’-bromophenyl)-1,2-benzanthracene was unsuccessful. An explanation of this anomaly was not discovered. C. The Grignard reagent or 2-(1-naphthylmethyl)-chloro-benzene was prepared by the use or tetrahydrofuran and "entrainment" with methyl iodide. / M.S.
36

Instrumentation and tar measurement systems for a downdraft biomass gasifier

Hu, Ming January 1900 (has links)
Master of Science / Department of Biological & Agricultural Engineering / Wenqiao Yuan / Biomass gasification is a promising route utilizing biomass materials to produce fuels and chemicals. Gas product from the gasification process is so called synthesis gas (or syngas) which can be further treated or converted to liquid fuels or certain chemicals. Since gasification is a complex thermochemical conversion process, it is difficult to distinguish the physical conditions during the gasification stages. And, gasification with different materials can result in different product yields. The main purpose of this research was to develop a downdraft gasifier system with a fully-equipped instrumentation system and a well-functioned tar measurement system, to evaluate temperature, pressure drop, and gas flow rate, and to investigate gasification performance using different biomass feedstock. Chromel-Alumel type K thermocouples with a signal-conditioning device were chosen and installed to monitor the temperature profile inside the gasifier. Protel 99SE was applied to design the signal conditioning device comprised of several integrated chips, which included AD 595, TS 921, and LM 7812. A National Instruments (NI) USB-6008 data acquisition board was used as the data-collecting device. As for the pressure, a differential pressure transducer was applied to complete the measurement. An ISA1932 flow nozzle was installed to measure the gas flow rate. Apart from the gaseous products yield in the gasification process, a certain amount of impurities are also produced, of which tar is one of the main components. Since tar is a critical issue to be resolved for syngas downstream applications, it is important to determine tar concentration in syngas. A modified International Energy Agency (IEA) tar measurement protocol was applied to collect and analyze the tars produced in the downdraft gasifier. Solvent for tar condensation was acetone, and Soxhlet apparatus was used for tar extraction. The gasifier along with the instrumentation system and tar measurement method were tested. Woodchips, Corncobs, and Distiller’s Dried Grains with Solubles (DDGS) were employed for the experimental study. The gasifier system was capable of utilizing these three biomass feedstock to produce high percentages of combustible gases. Tar concentrations were found to be located within a typical range for that of a general downdraft gasifer. Finally, an energy efficiency analysis of this downdraft gasifer was carried out.
37

Coal tar pitch volatiles exposure in a petrochemical refinery plant: a task based exposure assessment

Makgatho, Michael 23 March 2009 (has links)
This study describes tripper car operators’ exposure to coal tar pitch volatiles at an operation at Coal Distribution Steam Plant that involves the use of coal tar mix to feed as fuel the steam generating boilers. A cross-sectional task-based exposure assessment approached was used. The objectives of this study were to monitor tripper car operators’ exposures to coal tar pitch volatiles as benzene soluble fraction and to then compare the measured concentrations with the occupational exposure limit. The general aim of the study was to accumulate data about employee exposure to coal tar pitch volatiles in South African Petrochemical Refineries. A total of 56 samples was collected and analyzed for coal tar pitch volatiles – benzene soluble fraction. Of the 56 samples, 41 were personal samples collected on the breathing zones of the workers and 15 samples were field blank samples. The method used for the collection of the samples was the United States Department of Labor, Occupational Safety & Health Administration Method 58. In South Africa the available occupational exposure limit for coal tar pitch volatiles is the time weighted average occupational exposure limit – recommended limit for cyclohexane soluble fraction which is 0.14 mg/m3. For the evaluation of personal exposure to compare with the occupational exposure limit, the UK Health & Safety Executive Method for the Determination of Hazardous Substances (MDHS) 68 was adopted in the past to monitor workplace air. This method was since withdrawn by the Health & Safety Executive after research conducted by the Health & Safety Laboratory revealed that unacceptable variability were introduced into the method due to the small mass changes involved and the difficulty in accurately weighing the filters before and after the cyclohexane extraction. Due to the unavailability of a suitable and acceptable method to assess workers’ exposure to coal tar pitch volatiles – cyclohexane soluble fraction to compare to the South African occupational exposure limit, the Occupational Safety & Health Administration Method Number 58 was used during this study for the collection of the samples. This is a validated method. This method follows a similar approach as the MDHS 68 however benzene is used instead of cyclohexane during sample extraction. The Occupational Safety and Health Administration have the permissible exposure limit of 0.2 mg/m3 for coal tar pitch volatiles – benzene soluble fraction to use when assessing worker exposure. This limit was used during this study for assessing tripper car exposure to coal tar pitch volatiles. No coal tar pitch volatiles were detected on the samples collected during the study. The results revealed concentrations below detection limit of the test laboratory analytical method. The detection limit used thereof was 0.1 mg per sample. The tripper car operators were therefore exposed to coal tar pitch volatiles at concentrations that complied with the permissible exposure limit 0.2 mg/m3. The hypothesis of this study was that the tripper car operators at Coal Distribution Steam Plant are over exposed to coal tar pitch volatiles – benzene soluble fraction. This hypothesis is therefore rejected. Based on the results derived from this study it is recommended that further research studies be conducted specifically with focus on different methods of exposure assessment to workers exposed to coal tar pitch volatiles in South African Petrochemical Refinery Plants. - ii - Since the method used was limited to the particulate phase of the contaminant exposure, with the gaseous phase of exposure to coal tar pitch volatiles only looked at when the PEL is exceeded. A method that can measure both the gaseous and particulate phase of the contaminant must be investigated.
38

Polycyclic Aromatic Hydrocarbon Release from Pavement Rejuvenators Due to Rolling Wheel Contact: An Investigation Using a Model Mobile Load Simulator

Anderson, Joshua 23 April 2019 (has links)
Polycyclic aromatic hydrocarbon (PAH) compounds, which are common to coal tar and coal-tar-based products, are ubiquitous environmental contaminates with carcinogenic effects to human health and aquatic life. Transport of PAHs via solid phase particulate motion, gaseous phase volatilization, and aqueous phase dissolution into urban waterbodies of PAH compounds from coal-tar-based pavement sealant products has been studied. Pavement rejuvenators are products applied to increase the usable life of pavement. Coal-tar-based rejuvenators contain a significantly larger mass fraction of coal-tar with respect to coal-tar-based sealants, but pavement rejuvenators have not been as extensively studied as pavement sealants. Chemical analysis of detached pavement material treated with coal-tar-bases, asphalt-based, and bio-based rejuvenators was conducted with gas chromatography – mass spectrometry (GC/MS) analysis for 16 PAH compounds and two aromatic heterocyclic organic compounds following extraction with methylene chloride. Detached pavement material was collected from 19 simulated asphalt surface abrasion experiments that used a model mobile load simulator (MMLS) test apparatus that replicated surface challenges from vehicular traffic. The MMLS test apparatus configuration allowed asphalt disc samples treated with different rejuvenation products, to be tested and for detached material to be collected and quantified prior to GC/MS analysis. Test cases evaluated the influence of rejuvenation product type and cure time, as well as the effect of sand application (simulating sand application during slippery winter storm conditions) had on detached particulate and ultimate PAH compound loading. The average mass of particulate detachment from samples following a 48 hour cure time, for the asphalt-based and coal-tar-based rejuvenator products were 0.347 g and 0.480 g, respectively. This mass of detached material was lower than that from pavement treated with bio-based rejuvenator and the control (not treated), which had 4.858 g and 2.567 g of detached particulate material, respectively. When the product cure time was increased to three weeks, which was significantly long enough to capture effects of compound volatilization, average particulate detachment increased to 0.882 g for the coal-tar-based rejuvenator and decreased for the bio-based rejuvenator to 2.600 g. Six tests performed with a single application of winter storm sand after a 48 hour product cure time showed an increase in average particulate detachment to 1.450 g and 0.617 g for pavement treated with the asphalt-based and coal-tar-based rejuvenators, respectively. Conversely, under the same conditions, a reduction in average detached particulate to 3.749 g was observed for the bio-based product. Detached particulate material quantities for each test case were used with the respective cumulative concentration of 16 PAH compounds quantified to make an assessment on the potential PAH compound contamination via solid phase particle transport. The average PAH compound concentration in particulate detached from pavement treated with a coal-tar-based rejuvenator was 3062.8 mg PAH per kg of particulate. This was an order of magnitude higher than the average PAH concentration measured in particulate detached from the two control pavement samples and the two asphalt-based samples after a 48 hour cure time, which were 322.1 and 508.1 mg PAH per kg detached particulate, respectively. PAH compound concentrations were also normalized by the surface area of pavement treated with a rejuvenator to determine the potential PAH compound contamination per unit area. Normalized results for each rejuvenator type were averaged to make an overall evaluation of the potential rejuvenator specific PAH compound loading. The coal-tar-based, bio-based, and asphalt-based rejuvenators had a normalized cumulative solid-phase PAH compound release of 2.35, 0.88, and 0.17 mg PAH per square foot of pavement rejuvenated, respectively. In addition, carbazole was quantified in all pavement samples treated with the coal-tar-based rejuvenator at an average concentration of 125.6 mg carbazole per kg detached particulate. Acridine was quantified in detached particulate from five of seven coal-tar-based test performed at an average concentration (excluding non-detection samples) of 42.1 mg acridine per kg detached particulate.
39

Long-Term Fate of an Emplaced Coal Tar Creosote Source

Fraser, Michelle J January 2007 (has links)
An emplaced source of coal tar creosote within the sandy Borden research aquifer has provided an opportunity to document the long term (5140 days) natural attenuation for this complex mixture. Plumes of dissolved chemicals were produced by the essentially horizontal groundwater flowing at about 9 cm/day. Eleven chemicals were extensively sampled seven times using a monitoring network of ~280 14-point multilevel samplers. A model of source dissolution using Raoult’s Law adequately predicted the dissolution of nine of eleven compounds analysed. Mass transformation has limited the extent of the plumes as groundwater flowed more than 500 m yet the plumes are no longer than 50 m. Phenol and xylenes were removed and naphthalene was attenuated from its maximum extent on day 1357. Some compound plumes reached an apparent steady state and the plumes of other compounds (dibenzofuran and phenanthrene) are expected to continue to expand due to an increasing mass flux and limited degradation potential. Biotransformation is the major process controlling natural attenuation at the site. The greatest organic mass loss is associated with the high solubility compounds. However, the majority of the mass loss for most compounds has occurred in the source zone. Oxygen is the main electron acceptor yet the amount of organics lost cannot be accounted for by aerobic mineralization or partial mineralization alone. After 10 years the source zone was treated with permanganate in situ to reduce the flux of contaminants into the dissolved plume and to permit natural attenuation to further reduce the plume extent. A sufficient mass of permanganate was injected to oxidize ~10% of the residual source. Laboratory experiments demonstrated that eight of ten of the study compounds were readily oxidized by permanganate. Once treated oxidized compounds displayed a reduced plume mass and mass discharge while they migrated through the monitoring network. Once beyond the monitoring network the mass discharge and plume mass of these compounds returned to pre-treatment trends. Non-reactive compounds displayed no significant decrease in mass discharge or plume mass. Overall the partial in situ chemical oxidation of the coal tar creosote source produced no long-term effect on the dissolved plumes emanating from the source.
40

Long-Term Fate of an Emplaced Coal Tar Creosote Source

Fraser, Michelle J January 2007 (has links)
An emplaced source of coal tar creosote within the sandy Borden research aquifer has provided an opportunity to document the long term (5140 days) natural attenuation for this complex mixture. Plumes of dissolved chemicals were produced by the essentially horizontal groundwater flowing at about 9 cm/day. Eleven chemicals were extensively sampled seven times using a monitoring network of ~280 14-point multilevel samplers. A model of source dissolution using Raoult’s Law adequately predicted the dissolution of nine of eleven compounds analysed. Mass transformation has limited the extent of the plumes as groundwater flowed more than 500 m yet the plumes are no longer than 50 m. Phenol and xylenes were removed and naphthalene was attenuated from its maximum extent on day 1357. Some compound plumes reached an apparent steady state and the plumes of other compounds (dibenzofuran and phenanthrene) are expected to continue to expand due to an increasing mass flux and limited degradation potential. Biotransformation is the major process controlling natural attenuation at the site. The greatest organic mass loss is associated with the high solubility compounds. However, the majority of the mass loss for most compounds has occurred in the source zone. Oxygen is the main electron acceptor yet the amount of organics lost cannot be accounted for by aerobic mineralization or partial mineralization alone. After 10 years the source zone was treated with permanganate in situ to reduce the flux of contaminants into the dissolved plume and to permit natural attenuation to further reduce the plume extent. A sufficient mass of permanganate was injected to oxidize ~10% of the residual source. Laboratory experiments demonstrated that eight of ten of the study compounds were readily oxidized by permanganate. Once treated oxidized compounds displayed a reduced plume mass and mass discharge while they migrated through the monitoring network. Once beyond the monitoring network the mass discharge and plume mass of these compounds returned to pre-treatment trends. Non-reactive compounds displayed no significant decrease in mass discharge or plume mass. Overall the partial in situ chemical oxidation of the coal tar creosote source produced no long-term effect on the dissolved plumes emanating from the source.

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