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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.
1

Waste-to-Energy : A study on Reaction Kinetics of Tropical Wood Sawdust

Tita, Bertrand Asongwe January 2016 (has links)
The reaction kinetics of Iroko and Mahogany were studied using TGA. The pyrolysis process was achieved using six different heating rates of 2,5,8,12,15 and 20˚C. A 15˚C/min heating rate was used for gasification in steam at different temperatures while varying the concentrations of nitrogen and steam in the process. The kinetic parameters, activation energy and pre exponential factor, were obtained by implementing two chosen kinetic models. These models are: Friedman’s Iso-conversional Method, Flynn-Wall-Ozawa Method (FWO). There were substantial differences in the values of the kinetic triplets found from the experiments. Due to the substantial differences in the values, it was not the best way to perform this kind of analysis (which is the traditional way) but instead to use pure regression analysis; but using it for the whole data set (that means for all heating rates) and minimize the difference with experimental data.
2

Bubbling Fluidized Bed Gasification of Biomass and Refuse Derived Fuel

Robinson, Travis January 2015 (has links)
In Canadian remote northern communities most electricity is generated by burning diesel fuel. However, because it is expensive to import fuel into remote communities the cost of electricity is very high. Waste management is also difficult in remote northern communities. The goal of this thesis was to investigate the co-gasification of refuse waste materials and biomass as a means of reducing solid waste volumes while also using locally available materials for power generation. As part of this research, thermo-gravimetric analysis (TGA) was investigated as a potential means of characterizing refuse derived fuels (RDF). Laboratory sample preparation of RDF for TGA had not been thoroughly considered. Laboratory sample preparation is important since RDF is very heterogeneous compared to other solid fuels and since TGA typically requires a very small sample size. A TGA method was applied to a variety of materials prepared from a commercially available RDF using a variety of procedures. The repeatability of the experimental results was related to the sample preparation methods. Cryogenic ball milling was found to be an appropriate means of preparing RDF samples for TGA. Applicability of the TGA method to the determination of the renewable content of RDF was considered. Air-blown auto-thermal gasification experiments using materials representative of waste and biomass were performed at 725°C, 800°C, and 875°C, using a 0.15 m internal diameter bubbling fluidized bed gasifier located at NRCan CametENERGY in Ottawa, Ontario. Commercially prepared RDF and PET scrap were used to represent waste materials. Commercially produced hardwood pellets were used to represent biomass. The co-gasification of hardwood pellets and commercially produced RDF indicated that each fuel make a contribution to the results which is proportional to its fraction in the feed mixture. Inclusion of the RDF in the fuel mixture led to bed agglomeration at the 875°C temperature condition. Higher temperatures were found to provide better conversion of the fuel to gas, and the limitation which inclusion of RDF places on the operating temperature of the gasifier negatively affects conversion of biomass. Results obtained with RDF suggested that utilization of mixed waste for a thermal conversion process located in a Canadian remote northern community is probably not a viable option. It was then decided to target plastic waste in particular. Plastic could be source-separated, collected, and gasified alongside biomass. Polyethylene terephthalate (PET), which is often used for food and beverage containers, was chosen to represent plastic. Initially, attempts were made to co-gasify mixtures of PET pellets and hardwood pellets. These attempts failed due to the formation of coke above the bed. To alleviate these problems hardwood-PET composite pellets were manufactured and these were gasified at 725°C, 800°C, and 875°C. Inclusion of PET in the pellets dramatically increased the amount of tar produced during gasification.
3

Removal of selected chlorinated phenolic compounds from water sources in Vaal Triangle using HPLC, Macadamia nutshell activated carbon and solid phase extraction

Machedi, Sechaba 12 1900 (has links)
M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / In this study, analytical method for determining the chlorinated phenols in water was developed using High Performance Liquid Chromatography. The following four compounds which are 2, 4, 6- Trichlorophenol (2, 4, 6 TCP), 3-chlorophenol (3CP), 2, 4- Dichlorophenol (2, 4 DCP) and 4-chloro-3-methylphenol (4C3MP) were identified and quantified with a High Performance Liquid Chromatography (HPLC). The validation parameters tested were,: linearity, trueness, precision, detection limit of quantitation, sensitivity, specificity, selectivity. The linear calibration ranges of five standard solution from 1-10 ppm. The linearity ranges between 0.9298-0.9813. The activated carbon based on the waste macadamia nutshell activated carbon (MAC) was investigated for its potential uses as an adsorbent for chlorinated phenols removal and compared with grafted macadamia nutshell activated carbon (GMAC). The adsorbent was characterized with Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). The parameters such as pH, temperature, contact time, concentration and adsorbent were investigated by adsorption technique. The strata C18E has been used before for the same reason and therefore the research was based on mimic the functional group of solid phase extraction (SPE) into macadamia activated carbon (MAC). The functional groups in SPE C18E are benzene and octadecyl. MAC was grafted with strata C18E functional groups to compare its potential with the SPE. The pseudo-first-order and pseudo-second-order kinetic models were applied to verify the experimental data. The pseudo-second order exhibited the best fit for the kinetic studies for MAC adsorption. Chemical removal of chlorinated phenols from wastewater is necessary to reduce harmful products on the environment and human health. Chlorinated phenols have been previously listed as some of the highest priority contaminants and as well as mainly important capability carcinogenic toxins released from chemical plants. Their availability in water supplies was perceived by their bad taste and smell. The acceptable chlorinated phenols concentration in portable water is 1 (mg/l) base on the approval of world health organization. The permanent checking of chlorinated phenols in environmental samples has a greater significance and stresses highly effectiveness, common selectively and great sensitively methods. The maximum uptake of Phenol using weighed mass of MAC was found to be 78 % and for GMAC was 84% for both 2,4,6TCP. t=250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-MAC system and GMAC system. Over all analysis of equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of MAC. Phenol adsorption capacity of MAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. Characterization of MAC and GMAC confirmed the mesoporous texture, highly carbonaceous nature and a higher effective surface area of 912 m2/g. The highest phenol uptake capacity of GMAC was found to be 8.0049 mg/g. The optimal conditions for various process parameters are t = 250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-GMAC system. Like Phenol-MAC system, the kinetics studies confirmed that Phenol-GMAC adsorption system can be described by pseudo- second-order kinetics model. Equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol-MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of GMAC. Phenol adsorption capacity of GMAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. The negative values of Gibb’s free energy suggested that adsorption of phenol onto GMAC was a spontaneous process.

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