This study incorporates the potential use of Variable Frequency Drives on various motors as well as areas of improved heat transfer in an older, mid-sized coal fired power plant. In power plants, fluid flow rates are often controlled using dampers or valves while the motors that power the pumps stay at full speed resulting in a significant amount of wasted electrical power; energy is also lost due to poor heat recovery prior to gases leaving the system. By examining pump usage as well as additional heat available for recovery, potential energy savings will be determined. Preliminary results of five motors suggested for variable frequency drive application show annual savings that total 31.1 GWh, resulting in a 1.66% increase in overall plant efficiency. Total project costs are near $2 million resulting in a simple payback period of less than two years assuming 0.04 $/kWh. For every degree reduction of the flue gas temperature by means of heat recovery that is reused elsewhere in the cycle, 2 Billion BTU of coal would be saved annually. One realistic scenario suggested heat recovery resulting in a 120°F degree reduction of flue gas temperature amounting to a 2.54% increase in cycle efficiency.

The function of a flue-gas quench is to remove additional contaminants from flue-gas and to reduce the wastewater from a waste incineration plant. The aim of this degree project is to find how the system is affected by using a quench and what factors limits the performance. This is done by modelling and simulating a waste incineration plant in Aspen Plus. Data and plant schematics were obtained by a study visit to Mälarenergi Plant 6 situated in Västerås, Sweden, which were used as model input and for model validation. The results have shown that the amount of wastewater can be reduced by more than half compared to a plant without a quench. The heat produced in the condenser, when discharging water to the boiler, would be lowered by up to 20%. For systems with a quench present when more water was discharged to the boiler both the heat production and the pollutant capturing became better. However, the system has limits regarding the amount that could be recirculated, in the form of temperature limits in different parts of the system. In addition, if the heat load is low there is an insufficient amount of wastewater generated in the condenser to run the quench. In that situation, clean (fresh) water needs to be used instead. Using clean water is unwanted since the plant will then consume more resources while still producing less heat than a plant without a quench would.

Energy technologies interact with the economic, social and environmental systems, and do so not only directly but indirectly as well, through upstream and downstream processes. In addition, the interactions may produce positive and negative repercussions. To make informed decisions on the selection of energy technologies that assist a nation in reaping the socio-economic benefits of power generation technologies with minimal effects on the natural environment, energy technologies need to be understood in the light of the multifaceted system in which they function. But frequently, as disclosed by the literature review conducted in this research, the evaluation of energy technologies lacks clear benchmarks of appropriate assessments, which has resulted in difficulty to compare and to gauge the quality of various assessment practices. The assessment methods and tools tend to be discipline specific with little to no integrations. Parallel with the tools, the technology assessment studies offer piecemeal information that limits deeper understanding of energy technologies and their consequent socio-economic-environmental repercussions. Improved energy technology assessment requires the use of a holistic and integrative approach that traverses the disciplinary nature of energy technology assessment tools, examines the long-term implications of technologies while at the same time embracing energy technologies’ positive-and-negative interactions with the economic, social and environmental systems and in this manner offering economic, social and environmental indicators to assist decision makers in the decision-making process. Accordingly, this study focuses on improving the assessment of energy technologies through the application of a holistic and integrative approach, specifically system dynamics approach along a life-cycle viewpoint. Precisely, focus is on coal-based electricity generation and in particular, the Kusile coal-fired power station near eMalahleni as a case study. A COAL-based Power and Social Cost Assessment (COALPSCA) Model was developed for: (i) understanding coal-based power generation and its interactions with resource inputs, private costs, externalities, externality costs and hence its consequent socio-economic, and environmental impacts over its lifetime and fuel cycle; (ii) aiding coal-based power developers with a useful tool with a clear interface and graphical outputs for detecting the main drivers of private and externality costs and sources of socio-environmental burdens in the system; (iii) aiding energy decision makers with a visual tool for making informed energy-supply decisions that takes into account the financial viability and the socio-environmental consequences of power generation technologies; and for (iv) understanding the impacts of various policy scenarios on the viability of coal-based power generation. The validation of the COALPSCA Model was also conducted. Five structural validity tests were performed, namely structure verification, boundary adequacy, parameter verification, dimensional consistency and extreme condition tests. Behavioural validity was also conducted which included an analysis of the sensitivity of the model outcomes to key parameters such as the load factor, discount rate, private cost growth rates and damage cost growth rates using univariate and multivariate sensitivity analysis. Finally, while attempts were made to incorporate most of the important aspects of power generation in a coal-fired power plant, not all intrinsic aspects were incorporated due to lack of data, gaps in knowledge and anticipated model complication. The shortcomings of the model were highlighted and recommendations for future research were made. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Economics / PhD / Unrestricted

This thesis deals with a design of a steam boiler combusting natural gas. It consists of stoichiometric calculation, determination of boiler efficiency, thermal calculations and determining geometric parameters of the boiler and its heat transfer surfaces. The results are verified by the heat balance of the boiler.

The objective of the presented diploma thesis is reduction of nitrogen oxides from the flue gas stream on catalyst under non-standart conditions. Emphasis is places on the description of selected pollutants in flue gas (especially nitrogen oxides), legislative requirements for air protection and technologies for removal of nitrogen oxides, expecially methods of selective catalytic and non-catalytic reduction. The practical part is devoted to the reduction of nitrogen oxides by selective catalytic reduction on a pilot plant INTEQ II in the laboratory NETME Center. The subject of interest is the determination of the NOx reduction efficiency depend on the temperature for selected catalyst. The end of the practical part pursues with comparison of measurement results and their evaluation.

The purpose of the thesis is to create preliminary design calculations to determine dimensions, weights and pressure losses of individual contaminated biomass combustion gas treatment nodes. The first part of the thesis deals with the definition of biomass as a fuel, legislative determination of allowed emissions and their description. Then the systems for combustion gas treatments are discussed given their brief description. The practical part focuses on shape designs, determining base dimensions of each type. Weights and pressure losses of individual versions are computed too. In the last part the individual versions are solved with real values and compared to each other.

This thesis mainly deals with the thermal treatment of waste - hazardous waste incineration and energy recovery municipal waste incinerators - their descriptions and analysis of legislative conditions. The flue gas cleaning system energy production in different operating modes is assessed by energy and mass balances. Computational models are developed for this purpose. On this basis, productions of energy from thermal treatment of hazardous and communal waste were compared.

This thesis deals with thermal calculation and design of proportions and layout of calorific components of a heat recovery steam generator according to given output parameters of steam and input parameters of flue gas. Furthermore, the proportions of boiler drums and irrigation and transfer pipes are designed and draught losses are calculated.

This thesis deals with waste heat boiler for turbines burning natural gas. According to the given parameters of flue gas and vapor are carried out thermal balance and design of the boiler heating surfaces and calculated the dimensions and arrangement of heat transfer surfaces in the boiler followed by treatment with a drawing of the boiler.

This diploma work attends to presentation of steam grid boiler for wood and brown coal burning in scale (30/70-wood) in load 60t/h, with parametres of outgoing vapour p=7MPa, t=490°C. The work is splitted to several chapters. At the beginning I’m going to make stechiometric calculation and entalpic calculations of air and compustion gas. After that I’m going to calculate heat balance, losses of boiler and set heat efficiency of boiler. Then I’m going to suggest combustion chamber of boiler and make heat calculation. After suggestion of combustion chamber I’m going to set proportions of pulls and heat-delivery surface. In last chapter I’m giong to check heat balance. Inclosure of my work contains drawing documentation of steam boiler.