No description available.

The aim of this project is to investigate the possibilities of minimizing the sulphur content in Kraft lignin. Kraft lignin contains about 1.5 to 3% sulphur. The sulphur is believed to be present in lignin as inorganic sulphur, as elemental sulphur, as adsorbed polysulphide and/or as organically bound sulphur. For the determination of these different types of sulphur components, different approaches and methods were used. For the determination of inorganic sulphur, lignin was washed with water at pH 6 and pH 2 and the wash waters were analysed with ion chromatography (IC). For the determination of total sulphur content in the lignin, two methods were used; Schöniger combustion followed by ion chromatography (IC) and wet digestion followed by inductively coupled plasma (ICP). The elemental sulphur content in water-extracted lignin was determined after n-pentane extraction. ICP analysis was performed on the washed lignin. Calcium present in the lignin may bind polysulphides and thus be a source of the observed sulphur. The lignin was thus ion-exchanged to remove any calcium. To further investigate how the sulphur content in lignin can be decreased, two different types of reactions were performed on lignin; oxidation and reduction. The oxidation reactions were made in sodium hydroxide with oxygen at different temperatures and time on both original and water-extracted lignin. The reduction reactions were made on water-extracted lignin with Raney nickel in three different solvent systems: methanol: water, acetone: water and sodium hydroxide.   The original lignin contained 2.6% sulphur as determined by ICP. Washing lowered the content to 1.85% sulphur. By n-pentane extraction the elemental sulphur was lowered to a level of 1.82% sulphur, which was considered to be organically bound sulphur. Neither the ion exchange nor the oxidation lowered the sulphur content significantly.   The reduction reactions successfully the organically bound sulphur from 1.82% to a level of 0.54%.   The relative distribution of the sulphur content in the studied softwood lignin was as follows: about 29% as inorganic sulphur, about 1% as elemental sulphur and approximately 70% as organically bound sulphur, of which 49% could be removed by Raney nickel.

No description available.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The aim of this thesis is to design a desulphurization device for the fluid boiler. In the fluid boiler, fuel with extremely high sulphur content is burnt and the combustion products are not desulphurized to the required level, therefore it is necessary to build a desulphurization device. The thesis consists of two parts – theoretical and practical. In the theoretical part I stated the emission limits of sulphur dioxide, elaborated possible desulphurization methods and described the sorbets suitable for desulphurization. In the practical part I chose a dry desulphurization method with fluid reactor, to which a dry sorbent on the basis of lime hydrate is dosed. For the required parameters, I designed the whole desulphurization equipment including cloth filters, all necessary silos and major components. It is a design proposal with a layout and a spatial model.

The aim of this thesis is to design a desulphurisation device for the pulverized coal boiler K3 in heating plant Olomouc. In this boiler, coal with sulphur content is burnt. Emissions SOx from the boiler output are much higher than the emission limits for SOx, which comes into force 1.1.2016. Therefore it is necessary to build a desulphurisation device, which will cause a significant reduction of SOx emissions and compliance with the emission limits. The thesis consists of two parts - theoretical and practical. The theoretical part states SO2 emission limits and describes various methods for flue gas desulphurisation. In the practical part I chose a semi-dry desulphurisation method with fluid reactor. It determines a stoichiometric amount of combustion air and determines the boiler efficiency. For the required parametres is given a calculation of desulphurisation, the design of some parts of the device and design arrangement.

Magister Commercii - MCom / In order to comply with the Air Quality Act 2010, Eskom will have to install flue gas desulphurisation (FGD) plants for both new and old power stations. Wet-flue gas desulphurisation (wet-FGD) is adopted world-wide as an effective flue gas treatment technology and therefore will be adopted by Eskom. During the process of desulphurisation, the flue gas is stripped of SO2 but gains a substantial amount of water. Sustaining this process requires a continuous supply of fresh water, a scarce resource in many places where power stations are built. This research investigates the economic feasibility of technologies capable of recovering water from flue gas. The following technologies were considered to capture water vapour from flue gas taking Eskom’s Medupi Power Station as a case study; condensing heat exchanger technology, desiccant drying systems and membrane technology using membrane modules developed by other students in this project. The water vapour selective membrane technology turned out to be superior.

In order to optimise the ladle treatment mass transfer modelling of aluminium addition and homogenisation time was carried out. It was stressed that incorporating slag-metal reactions into the mass transfer modelling strongly would enhance the reliability and amount of information to be analyzed from the CFD calculations.   In the present work, a thermodynamic model taking all the involved slag metal reactions into consideration was incorporated into a 2-D fluid flow model of an argon stirred ladle. Both thermodynamic constraints and mass balance were considered. The activities of the oxide components in the slag phase were described using the thermodynamic model by Björkvall and the liquid metal using the dilute solution model. Desulphurization was simulated using the sulphide capacity model developed by KTH group. A 2-D fluid flow model considering the slag, steel and argon phases was adopted.   The model predictions were compared with industrial data and the agreement was found quite satisfactory. The promising model calculation would encourage new CFD simulation of 3-D along this direction. / QC 20110414