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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.
21

Enzymatic hydrolysis of cellulosic fiber

Rao, Swati Suryamohan. January 2009 (has links)
Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Banerjee Sujit; Committee Member: Deng Yulin; Committee Member: Haynes Danny. Part of the SMARTech Electronic Thesis and Dissertation Collection.
22

Reaction engineering of heterogeneous feeds : municipal solid waste as a model /

Lai, Wei-Chuan, January 1991 (has links)
Thesis (Ph. D.)--University of Washington, 1991. / Vita. Includes bibliographical references (leaves [261]-271).
23

Energy production from poultry waste development and application of an economic model to compare various concepts /

Dickens, Ricky Everette. January 2008 (has links) (PDF)
Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Sept. 15, 2009). Thesis advisor: Atul Sheth. Vita. Includes bibliographical references.
24

Biofuels from lignin and novel biodiesel analysis

Nagy, Máté. January 2009 (has links)
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Ragauskas, Arthur; Committee Member: Bunz, Uwe; Committee Member: Deng, Yulin; Committee Member: Singh, Preet; Committee Member: Soper, Jake. Part of the SMARTech Electronic Thesis and Dissertation Collection.
25

Diesel fuel extender from animal waste

Eddy, Laura S. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vii, 75 p. : ill. Includes abstract. Includes bibliographical references (p. 50-51).
26

Catalytic conversion of alcohol-waste vegetable oil mixtures over aluminosilicate catalysts

Ganda, Elvis Tinashe January 2018 (has links)
Submitted in fulfillment of the requirements for the degree of Master of Engineering: Chemical Engineering, Durban University, Durban, South Africa, 2018. / Thermochemical catalytic conversion of ethanol-waste cooking oil (eth-WCO) mixtures was studied over synthesised aluminosilicate catalysts HZSM-5, FeHZSM-5 and NiHZSM-5. The thermochemical reactions were carried out at temperatures of 400° and 450°C at a fixed weight hourly space velocity of 2.5 h-1 in a fixed bed reactor system. Successful conversion of the eth-WCO mixtures was carried out over the synthesised catalyst systems and in order to fully understand the influence of the catalysts, several techniques were used to characterise the synthesised materials which include XRD, SEM, EDS, BET techniques. Results of the catalyst characterisation showed that highly crystalline solid material had been formed as evidenced by the high relative crystallinity in comparison with the commercial HZSM-5 catalyst at 2θ peak values of 7°- 9° and 23°- 24°. The introduction of metals decreased the intensity of the peaks leading to lower values of relative crystallinity of 88% and 90% for FeHZSM-5 and NiHZSM-5, respectively. However this was even slightly higher than the commercial sample which had a value of 86% with respect to HZSM-5 synthesised catalyst taken as reference material. There was no significant change in XRD patterns due to the introduction of metal. Elemental analysis done with energy dispersive spectroscopy showed the presence of the metal promoters (Fe, Ni) and the Si/Al ratio obtained from this technique was 38 compared to the target ratio of 50 set out initially in the synthesis. From the SEM micrographs the morphology of the crystals could be described as regular agglomerated sheet like material. Surface area analysis showed that highly microporous crystals had been synthesised with lower external surface area values ranging from 57.23 m2/g - 100.82 m2/g compared to the microporous surface area values ranging from 195.96 m2/g to 212.51 m2/g. For all catalyst employed in this study high conversions were observed with values of over 93 %, almost total conversion was achieved for some samples with values as high as 99.6 % with FeHZSM-5 catalysts. Despite the high level of conversion the extent of deoxygenation varied with lower values recorded for FeHZSM-5 (25%WCO) at 400°C and NiHZSM-5 (75%WCO) at 450°C with oxygenated hydrocarbons of 19.5% and 19.33% respectively. The organic liquid product yield comprised mostly of aromatic hydrocarbon (toluene, p-xylene and naphthalene) decreased with the introduction of metal promoters with NiHZSM-5 producing higher yields than FeHZSM-5. For the pure waste cooking oil (WCO) feedstock the parent catalyst HZSM-5 had a liquid yield of 50% followed by NiHZSM-5 with 44% and lastly FeHZSM-5 had 40% at 400°C which may be seen to follow the pattern of loss of relative crystallinity. An increase in operating temperature to 450°C lowered the quantity of organic liquid product obtained in the same manner with the HZSM-5 parent catalyst still having the highest yield of 38% followed by Ni-HZSM-5 with 36% and Fe-HZSM-5 having a value of 30% for pure waste cooking oil feedstock which may be attributed to thermally induced secondary cracking reactions. For all catalyst systems with an increase in the content of waste cooking oil from 25% to 100% in the feed mixture there was a linearly increasing trend of the liquid product yield. HZSM-5 catalyst increased from 14% to 50% while FeHZSM-5 increased from 16% to 40% and NiHZSM-5 increased from 12% to 44% at a temperature setting of 400°C with lower values observed at 450°C.Results obtained in this study show the potential of producing aromatics for fuel and chemical use with highly microporous zeolite from waste material such as waste cooking oil forming part of the feedstock. / M
27

Modelling and characterisation of the pyrolysis of secondary refuse fuel briquettes and biomass materials

Liu, Yi January 2010 (has links)
This research was established due to an increase of interest in renewable energy sources and utilisation of various wastes and biomass. Gasification is currently one of the most promising thermal-chemical conversion techniques for recovering energy from waste, and the pyrolytic behaviour of secondary refuse fuel (SRF) briquettes and biomass-derived fuels is the starting point for the process. The purpose of this study was to evaluate the pyrolytic characteristics of SRF briquettes and biomass materials, suggest a kinetic model for simulating the pyrolytic process and obtaining the kinetic parameters, and then predict the yield of volatile products in pyrolysis. Knowledge of the chemical composition, the thermal behaviour and the reactivity of SRF briquettes and their blends with other materials, such as biomass and plastic during pyrolysis is very important for the effective design operation of gasification units. The kinetics of the pyrolysis of simulated SRF briquettes, SRF briquettes and pulverised biomass samples was successfully modelled by a scheme consisting of two independent general order parallel reactions of the main components which were hemicellulose, cellulose, lignin and plastic. The kinetic parameters estimated through the model were comparable with those reported in the literature. In this research, activation energy values varied between 30 – 70 kJ/mol for lignin pyrolysis, 96 – 137 kJ/mol for hemicellulose and cellulose pyrolysis, and about 260 kJ/mol for plastic pyrolysis. Biomass has a very high volatile content. Adding biomass into SRF briquettes could increase the volatile yield. Increasing the plastic content of SRF briquettes could increase the volatile yield, the derivative thermogravimetric (DTG) peak height and the repeatability of pyrolysis. Inorganic component could shift the cellulose pyrolysis to a lower temperature and cause the hemicellulose pyrolysis and the cellulose pyrolysis highly overlapped, but it could have a positive effect by acting as catalysts and lower the activation energy in the pyrolysis of hemicellulose and cellulose. Molasses used as a binder could improve the DTG peak height and restrain the curve shifting effect of inorganic component on the hemicellulose and cellulose pyrolysis, but couldn’t restrain the lignin pyrolysis at low temperatures during the hemicellulose and cellulose pyrolysis. Molasses could restrain the effect of the lignin pyrolysis at high temperatures on the plastic pyrolysis. Mechanical biological treatment (MBT) process could highly improve the volatile yield and improve the DTG peak height of SRF briquettes.
28

Drying of hog fuel in a fixed bed

Sheikholeslami, Roya January 1990 (has links)
Hog fuel is increasingly becoming an alternative to alleviate the energy problems associated with the use of fossil fuels. To make adequate use of hog fuel, its moisture content should be reduced prior to combustion either in an external dryer or in the initial stages of a hog fuel boiler. Therefore, this research project was undertaken to establish the factors which govern the drying rate of wet hog fuel particles. The convective drying of wood-waste on the slow moving bed of hog fuel boilers was simulated in a packed bed. The information which was obtained can also be applied to approximate the drying behaviour in external dryers. An apparatus was constructed to accommodate the use of hot air, flue gas, superheated steam and a mixture of them as drying media. Drying tests were carried out, over the temperature range of 125-245°C, on 1.1 to 4 kg batches of Western Hemlock hog fuel of thicknesses from 2 to 12 mm. The relative effects of velocity (V), temperature (T), nature of the drying gas, bed depth (L), and initial moisture content of the hog fuel samples (M₀) on the drying process were investigated using a mixture of several thickness fractions having an average (sauter mean) particle thickness (dp) of 6.3 mm. Drying rates were determined through measurement of the change either in humidity of the drying gas, or flow rate of the superheated steam across the bed of hog fuel. Gas humidity was measured using an optical dew point sensor and steam flow was monitored using an orifice plate connected to a massflow transmitter. Drying rates have been quantified as functions of hog fuel particle thickness, initial moisture content and bed depth. The effects of gas temperature, velocity and humidity have also been quantitatively established. The drying process was insensitive to CO₂ content of the drying gas. The existence of an inversion temperature above which drying rates increase with humidity of the drying medium was both experimentally and theoretically confirmed and the locus of inversion points was determined. Instantaneous normalized drying rates, ƒ, and characteristic moisture contents, Φ , have been determined and the existence of a unified characteristic drying rate curve was verified. Using a receding plane model, ƒ was formulated as a function of Φ, for dp = 6.3 mm and at L = 25 cm, for both superheated steam and relatively dry air. Pressure drop measurements were obtained for all the runs with the exception of the superheated steam ones. Application of an accepted pressure drop equation permitted the sphericity of the hog fuel particles to be approximated. A design equation for gas pressure drop in beds of hog fuel particles was investigated. The simultaneous heat and mass transfer processes in drying during the heat transfer controlled period was studied. Using the concept of volumetric evaporation, an empirical correlation for the overall heat transfer coefficient in a packed bed of hog fuel particles has been obtained. The effects of different parameters on both the particle residence time required for drying and the grate heat release rate in hog fuel boilers were determined. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate
29

The Technical and Economic Feasibility of Producing Methane from Biomass Using a Leaching-Bed/Packed-Bed Conversion Process

Hinton, Steven W. 01 January 1983 (has links) (PDF)
The economic feasibility and energy effectiveness of producing pipeline quality methane gas from biomass was assessed for a new and totally unproven process. The biomass feedstock considered was the common aquatic weed water hyacinth and a novel active boom-winch harvesting system is proposed for its collection. The conversion process analyzed is a two stage biological process which utilizes a leaching-bed for the production of volatile acids and a packed-bed for the production of methane gas. In order to determine the feasibility of the proposed process equipment requirements, capital costs and operating/maintenance costs were developed for three system sizes. This data was analyzed using a life cycle cost model to determine pay back period. The results indicate that payoff period will be less than equipment life and that net energy production occurs. Areas where further research would promote the introduction of this technology are identified and discussed.
30

Effects on Iron and Cobalt on Methane Production from Dairy Cattle Manure

Himes, Mark E. 01 January 1983 (has links) (PDF)
The effects of iron and cobalt on methanogenesis from dairy cattle manure were studied. Four-liter digestors with 3-liter working volumes were charged daily with dairy manure (4.5% W/V volatile solids) to achieve a 3-day retention time. Digestors were incubated at 37°C and pH 7.0 on a rotary shaker. Duplicate digestors were maintained under the following parameters: controls (no ions added), Co++ at 4.958 mg/liter, Fe++ at 20.64 mg/liter and Fe++ and Co++ at above stated final digestor concentrations. Significantly higher production of biogas and methane occurred with the addition of iron (p = .05). Iron-amended digestors produced 3.88 ± 0.26 liters/liter/day of biogas and 2.03 ± 0.14 liters/liter/day of methane. Control digestors produced 3.59 ± 0.27 liters/liter/day of biogas and 1.85 ± 0.14. Cobalt did not stimulate methanogenesis and may have nullified the stimulating effects of iron. Neither the cobalt nor the iron/cobalt-amended digestors demonstrated increases in biogas or methane production. Iron or cobalt did not affect efficiency of fermentation (liters of methane per gm of volatile solids destroyed) or volatile fatty acid conversion. The total counts of methanogens grown in roll tubes were unaffected by addition of the metals. Methanobrevibacter smithii was isolated from all digestors, however, Methanobacterium formicicum was isolated only from digestors amended with iron.

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