A comparative study of emissions from coal-fired power stations in South Africa and other selected countries
- Authors: Wilreker, Gerlinde Isabelle
- Date: 2009-01-29T12:09:40Z
- Subjects: Coal-fired power plants , Australia , Canada , Germany , India , South Africa
- Type: Thesis
- Identifier: uj:14854 , http://hdl.handle.net/10210/1976
- Description: M.Sc. , Worldwide, coal is one of the major sources of energy. In 1999 it was estimated that the global electricity generation from coal was about 36% of the total world electricity production (Knapp, 1999:11). With the combustion of coal for electricity generation however, negative environmental impacts occur. These are mainly caused by carbon dioxide, nitrous oxides, sulphur dioxide and particulate matter emissions. With an ever-growing global population, the need and demand for electricity is increasing. These needs and demands need to be addressed in an economically, socially and environmentally acceptable manner. In this study the author examines, analyses and compares the emissions from coalfired power stations in South Africa, Australia, Canada, Germany, India and the United States of America over a chosen period of time (1995-2001). The results of the study indicate, that, within the comparative group, South Africa is not the greatest producer of emissions from coal-fired power stations. It is the fourth biggest emitter of CO2. It has the highest SO2 emissions, because of the low-grade coal burned in the power stations that have been specifically designed to burn this type of coal. It is the second biggest emitter of NOx, and the third biggest emitter of particulates. Germany is the country that has shown the greatest progress in emissions reductions. This has been the result of restructuring and economic incentives. Overall, South Africa can be ranked third, on par with Australia.
- Full Text:
- Authors: Wilreker, Gerlinde Isabelle
- Date: 2009-01-29T12:09:40Z
- Subjects: Coal-fired power plants , Australia , Canada , Germany , India , South Africa
- Type: Thesis
- Identifier: uj:14854 , http://hdl.handle.net/10210/1976
- Description: M.Sc. , Worldwide, coal is one of the major sources of energy. In 1999 it was estimated that the global electricity generation from coal was about 36% of the total world electricity production (Knapp, 1999:11). With the combustion of coal for electricity generation however, negative environmental impacts occur. These are mainly caused by carbon dioxide, nitrous oxides, sulphur dioxide and particulate matter emissions. With an ever-growing global population, the need and demand for electricity is increasing. These needs and demands need to be addressed in an economically, socially and environmentally acceptable manner. In this study the author examines, analyses and compares the emissions from coalfired power stations in South Africa, Australia, Canada, Germany, India and the United States of America over a chosen period of time (1995-2001). The results of the study indicate, that, within the comparative group, South Africa is not the greatest producer of emissions from coal-fired power stations. It is the fourth biggest emitter of CO2. It has the highest SO2 emissions, because of the low-grade coal burned in the power stations that have been specifically designed to burn this type of coal. It is the second biggest emitter of NOx, and the third biggest emitter of particulates. Germany is the country that has shown the greatest progress in emissions reductions. This has been the result of restructuring and economic incentives. Overall, South Africa can be ranked third, on par with Australia.
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Assessment of combustion products and uranium alkaline leaching of Springbok Flats uniferous coal
- Authors: Sekatane, P.L.
- Date: 2018
- Subjects: Coal - Environmental aspects , Clean coal technologies , Coal-fired power plants , Combustion products , Coal - Combustion
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269662 , uj:28649
- Description: Abstract: The department of mineral resources has seen a need for South African coal researchers and metallurgists to conduct research for cleaner coal processing and energy production, and thus created intervention strategies for the optimal beneficiation of the coal. The Geoscience conducted the first coordinated exploration programme in the springbok area between 1952 and 1972. A total of 27 boreholes (BHs) where drilled in the northern stern portion of the coalfield. Five boreholes were drilled in the SFC (BH1 to BH5); BH5 had two coal zones, an upper coal zone (UCZ) and a lower coal zone coal (LCZ), but the focus on this study was on borehole two and borehole one. The samples from borehole two were subjected to combustion and from borehole one was subjected to alkaline leaching for the recovery of uranium. The selected coal samples named 1426, 1427, 1428 and 1429 were characterised for proximate and calorific value while both raw samples and combusted were analysed using successively X-ray diffraction, X-ray fluorescence, FTIR and SEM incorporated with EDS. Results obtained showed that the calorific value (CV) ranged from13.4 MJ/Kg to a maximum 22.4 MJ/Kg, with 1427 having the highest CV (22.4 MJ/Kg) and 1428 having the lowest CV (13.4 MJ/Kg). Inherent moisture, volatile matter, ash content and fixed carbon of 1427 after proximate analysis were 2.4, 29, 32.1 and 44.1 wt% respectively. The coal samples labelled 1436, 1437, 1439 and 1440 were selected for alkaline leaching. Results obtained showed that uranium (Ur) was successfully leached from coal samples into solution, where all samples registered high uranium recoveries when leached at high temperature (65℃,85℃ and 105℃), pH (10, 10.5, and 11), and longer time (24, 48, and 96hours). Results obtained from combustions showed that during combustion only small quantities of uranium were released to the atmosphere, therefore it will not be necessary to leach before combustion. The parts per billion (ppb) differences in Ur content varied from 1 ppb registered by sample 1428 to 21 ppb registered by sample 1426, when combusted at 800°C and the ppb difference in Ur content varied from 2 ppb registered by sample 1427 and 1428 to 13 ppb registered by sample 1429, when combusted at 900°C. , M.Tech. (Extraction Metallurgy)
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- Authors: Sekatane, P.L.
- Date: 2018
- Subjects: Coal - Environmental aspects , Clean coal technologies , Coal-fired power plants , Combustion products , Coal - Combustion
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269662 , uj:28649
- Description: Abstract: The department of mineral resources has seen a need for South African coal researchers and metallurgists to conduct research for cleaner coal processing and energy production, and thus created intervention strategies for the optimal beneficiation of the coal. The Geoscience conducted the first coordinated exploration programme in the springbok area between 1952 and 1972. A total of 27 boreholes (BHs) where drilled in the northern stern portion of the coalfield. Five boreholes were drilled in the SFC (BH1 to BH5); BH5 had two coal zones, an upper coal zone (UCZ) and a lower coal zone coal (LCZ), but the focus on this study was on borehole two and borehole one. The samples from borehole two were subjected to combustion and from borehole one was subjected to alkaline leaching for the recovery of uranium. The selected coal samples named 1426, 1427, 1428 and 1429 were characterised for proximate and calorific value while both raw samples and combusted were analysed using successively X-ray diffraction, X-ray fluorescence, FTIR and SEM incorporated with EDS. Results obtained showed that the calorific value (CV) ranged from13.4 MJ/Kg to a maximum 22.4 MJ/Kg, with 1427 having the highest CV (22.4 MJ/Kg) and 1428 having the lowest CV (13.4 MJ/Kg). Inherent moisture, volatile matter, ash content and fixed carbon of 1427 after proximate analysis were 2.4, 29, 32.1 and 44.1 wt% respectively. The coal samples labelled 1436, 1437, 1439 and 1440 were selected for alkaline leaching. Results obtained showed that uranium (Ur) was successfully leached from coal samples into solution, where all samples registered high uranium recoveries when leached at high temperature (65℃,85℃ and 105℃), pH (10, 10.5, and 11), and longer time (24, 48, and 96hours). Results obtained from combustions showed that during combustion only small quantities of uranium were released to the atmosphere, therefore it will not be necessary to leach before combustion. The parts per billion (ppb) differences in Ur content varied from 1 ppb registered by sample 1428 to 21 ppb registered by sample 1426, when combusted at 800°C and the ppb difference in Ur content varied from 2 ppb registered by sample 1427 and 1428 to 13 ppb registered by sample 1429, when combusted at 900°C. , M.Tech. (Extraction Metallurgy)
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Effects of condenser performance on thermal heat rate
- Authors: Narainsingh, Soomesh
- Date: 2014-03-17
- Subjects: Coal-fired power plants , Heat - Transmission , Condensers (Steam)
- Type: Thesis
- Identifier: uj:4346 , http://hdl.handle.net/10210/9695
- Description: M.Tech. (Mechanical Engineering) , Eskom fossil fuel power stations operate under various conditions and the ageing fleet of fossil fuel power stations are under strain due to the rising demand in electricity. The quest for cheaper electricity in growing businesses and bringing foreign investment into South Africa is significant for economic growth. Therefore, minimizing operation costs and improving availability, reliability and thermal heat rate are key objectives for the operation of the business. Thermal heat rate calculation is a method used to assess the performance of fossil fuel power stations. It provides an indication of the thermal performance which reflects the condition and operation of the plant. This dissertation refers to the tools used to measure the condenser performance and to identify the reason for unhealthy condenser performance and an increase in thermal heat rate. Problem: Poor condenser performance causes significant losses in generation and thermal heat rate in fossil fuel plants. Loss in generation and thermal heat rate is caused by condenser backpressure. This has an adverse effect on turbine thermal heat rate and henceturbine efficiency. The performance of the condenser affects the turbine performance to a large extent. Decreased condenser performance will increase the turbine thermal heat rate, i.e. kJ/kWh, because of the increased steam consumption per kWh of energy generated and therefore lowering the overall turbine efficiency. This will result in poor thermal heat rate efficiency resulting in an increased coal burn rate, i.e. kg/kWh, and an increased fuel bill and carbon foot print for the fossil fuel power station. The aim of this dissertation is to determine the effects of condenser performance on thermal heat rate and to provide the engineering and operating personnel with a guide for monitoring condenser back pressure in order to improve turbine thermal heat rate and turbine efficiency. Method and Procedure: Chapter 4 describes the method and procedure used for the pre and post outage evaluation to cost-effectively determine the current condition of the condenser and to quantify the increase in thermal heat rate due to condenser degradation. The pre and post outage evaluation offered an opportunity to evaluate and quantify the effectiveness of the maintenance program and the value of the capital layout undertaken during the scheduled Unit outage. Findings: Chapter 5 discusses the findings of the pre and post outage data analysis of the condenser using the EtaPRO system as the tool. Re-tubing 50% of the condenser inner loop tubes and cleaning the other 50% of the outer loop tubes demonstrated a decrease in condenser backpressure and therefore an improvement in thermal heat rate. This will also result in an improvement in turbine cycle efficiency and reduce coal cost.
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- Authors: Narainsingh, Soomesh
- Date: 2014-03-17
- Subjects: Coal-fired power plants , Heat - Transmission , Condensers (Steam)
- Type: Thesis
- Identifier: uj:4346 , http://hdl.handle.net/10210/9695
- Description: M.Tech. (Mechanical Engineering) , Eskom fossil fuel power stations operate under various conditions and the ageing fleet of fossil fuel power stations are under strain due to the rising demand in electricity. The quest for cheaper electricity in growing businesses and bringing foreign investment into South Africa is significant for economic growth. Therefore, minimizing operation costs and improving availability, reliability and thermal heat rate are key objectives for the operation of the business. Thermal heat rate calculation is a method used to assess the performance of fossil fuel power stations. It provides an indication of the thermal performance which reflects the condition and operation of the plant. This dissertation refers to the tools used to measure the condenser performance and to identify the reason for unhealthy condenser performance and an increase in thermal heat rate. Problem: Poor condenser performance causes significant losses in generation and thermal heat rate in fossil fuel plants. Loss in generation and thermal heat rate is caused by condenser backpressure. This has an adverse effect on turbine thermal heat rate and henceturbine efficiency. The performance of the condenser affects the turbine performance to a large extent. Decreased condenser performance will increase the turbine thermal heat rate, i.e. kJ/kWh, because of the increased steam consumption per kWh of energy generated and therefore lowering the overall turbine efficiency. This will result in poor thermal heat rate efficiency resulting in an increased coal burn rate, i.e. kg/kWh, and an increased fuel bill and carbon foot print for the fossil fuel power station. The aim of this dissertation is to determine the effects of condenser performance on thermal heat rate and to provide the engineering and operating personnel with a guide for monitoring condenser back pressure in order to improve turbine thermal heat rate and turbine efficiency. Method and Procedure: Chapter 4 describes the method and procedure used for the pre and post outage evaluation to cost-effectively determine the current condition of the condenser and to quantify the increase in thermal heat rate due to condenser degradation. The pre and post outage evaluation offered an opportunity to evaluate and quantify the effectiveness of the maintenance program and the value of the capital layout undertaken during the scheduled Unit outage. Findings: Chapter 5 discusses the findings of the pre and post outage data analysis of the condenser using the EtaPRO system as the tool. Re-tubing 50% of the condenser inner loop tubes and cleaning the other 50% of the outer loop tubes demonstrated a decrease in condenser backpressure and therefore an improvement in thermal heat rate. This will also result in an improvement in turbine cycle efficiency and reduce coal cost.
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Submerged scraper conveyor operation and maintenance under changing operational environment
- Authors: Mahlangu, Linda
- Date: 2017
- Subjects: Conveying machinery , Service life (Engineering) , Coal-fired power plants , Boilers - Maintenance and repair , Plant maintenance
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269779 , uj:28663
- Description: M.Ing. (Engineering Management) , Abstract: This research seeks to identify whether a plant’s life cycle is affected as a result of changing operational parameters. The research has been necessitated by the fact that despite great advancements in power plant operation and maintenance theory, South Africa’s coal fired power plants still experience high down time due changing operational conditions. Submerged Scraper Conveyors (SSCs) have been identified as the equipment to be analysed for this research. They are critical for removal of Bottom Boiler Ash (BBA) from underneath coal fired power production units. This research is a continuation of work done by Wiid and Sawa-Bialogorski (2005) who investigated the behavior of ash during transportation and dewatering in an SSC. In order to investigate these parameters, a 1/10 scale model based on the SSC installed at Kendal power station is built and experiments are conducted. Wiid and Sawa-Bialogorski have further conducted experiments on a full-scale SSC installed under a 660 MW boiler at Matimba power station. This research is aimed at personnel involved at different phases of a plant’s life cycle as well as top management who set long term strategic goals for organizations. Findings of this research should highlight strategies which can be applied when organizations experience environmental changes which can affect plant life cycles. From an SSC point of view, findings of this research can be used by plant operators, maintainers and system engineers to provide reliable SSC equipment. The body of knowledge of SSC equipment will be enhanced, and how they can be designed and operated efficiently in South African plants. This research seeks to respond to the following main research questions: Are systems’ life cycle phases interlinked by forwards and feedback loops which help ensure that parameters and constraints are always favourable to the system’s life cycle. Is a system’s life cycle influenced by parameters and constraints found at different phases of the system’s life cycle? In order to address the research questions, a literature survey is presented in chapter 2. The literature survey is split into three sub sections which focus on power producing plants, plant life cycle, and factors which cause changes to a plant’s life cycle...
- Full Text:
- Authors: Mahlangu, Linda
- Date: 2017
- Subjects: Conveying machinery , Service life (Engineering) , Coal-fired power plants , Boilers - Maintenance and repair , Plant maintenance
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269779 , uj:28663
- Description: M.Ing. (Engineering Management) , Abstract: This research seeks to identify whether a plant’s life cycle is affected as a result of changing operational parameters. The research has been necessitated by the fact that despite great advancements in power plant operation and maintenance theory, South Africa’s coal fired power plants still experience high down time due changing operational conditions. Submerged Scraper Conveyors (SSCs) have been identified as the equipment to be analysed for this research. They are critical for removal of Bottom Boiler Ash (BBA) from underneath coal fired power production units. This research is a continuation of work done by Wiid and Sawa-Bialogorski (2005) who investigated the behavior of ash during transportation and dewatering in an SSC. In order to investigate these parameters, a 1/10 scale model based on the SSC installed at Kendal power station is built and experiments are conducted. Wiid and Sawa-Bialogorski have further conducted experiments on a full-scale SSC installed under a 660 MW boiler at Matimba power station. This research is aimed at personnel involved at different phases of a plant’s life cycle as well as top management who set long term strategic goals for organizations. Findings of this research should highlight strategies which can be applied when organizations experience environmental changes which can affect plant life cycles. From an SSC point of view, findings of this research can be used by plant operators, maintainers and system engineers to provide reliable SSC equipment. The body of knowledge of SSC equipment will be enhanced, and how they can be designed and operated efficiently in South African plants. This research seeks to respond to the following main research questions: Are systems’ life cycle phases interlinked by forwards and feedback loops which help ensure that parameters and constraints are always favourable to the system’s life cycle. Is a system’s life cycle influenced by parameters and constraints found at different phases of the system’s life cycle? In order to address the research questions, a literature survey is presented in chapter 2. The literature survey is split into three sub sections which focus on power producing plants, plant life cycle, and factors which cause changes to a plant’s life cycle...
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An assessment of the impact of dry and wet cooling systems on stake holders
- Authors: Jonker, Markus Smith
- Date: 2012-02-06
- Subjects: Eskom (Firm) , Cooling towers , Coal-fired power plants , Water consumption management
- Type: Thesis
- Identifier: uj:1972 , http://hdl.handle.net/10210/4329
- Description: M.Ing. , Water gives life. It waters the fields of farmers; it nurtures the crops and stock of rural communities; it provides recreation for our children, our friends, our families; it supports our power generation, our mines, our industry, and the plants and animals that make up ecosystems. Water is the key to development and a good quality of life in South Africa. South Africa's water belongs to its people. It is the task of the South African Government to care for this water, to seek its fair distribution, and to facilitate its wise use for, amongst other things, social and economical development. Issues such as water resource management, use, protection, water services, etc., are presently governed by a number of policies, acts and regulations. All South Africans has a responsibility regarding the management of the country's resources. The supply of water to its entire people makes it extremely important to optimise the use of this scarce source. Access to water and water availability remains a key factor in ensuring the sustainability of development in Southern Africa. The coal fired power industry is a major user of natural resources; coal for fuel and water for steam generation as well as the cooling systems. It is estimated that 1.5% of the water abstracted in South Africa is used for power generation. The power industry receives its water mainly as abstraction from surface impoundments in the form of rivers and dams. Eskom, as a strategic user of water, is mindful of the importance of water to its business, as well as the development of the country. In addition to the interests of the government as the shareholder, Eskom recognises the legitimate interests, as stakeholders, of specific government departments, employees, consumers, suppliers, investors and lenders of capital, rating agencies, the media, policy and regulatory bodies, trade unions, non-governmental groups and local communities in its affairs. Eskom needs to ensure, through an effective water management strategy, that water is used wisely and effectively and that Eskom's impact on local water resources (surface and underground) is minimised. Eskom therefore has to manage water resources in a manner that will sustain the ecological integrity, support social development and ensure economic growth. Eskom has undertaken to benchmark the power generation industry, in co-operation with the DW AF, in a project aimed at developing the principles of water conservation and water demand management. In order to effectively manage water quality and quantity at Eskom's power stations, and to show Eskom's commitment with regard to water conservation and use, Eskom has compiled its own water and environmental policies.
- Full Text:
- Authors: Jonker, Markus Smith
- Date: 2012-02-06
- Subjects: Eskom (Firm) , Cooling towers , Coal-fired power plants , Water consumption management
- Type: Thesis
- Identifier: uj:1972 , http://hdl.handle.net/10210/4329
- Description: M.Ing. , Water gives life. It waters the fields of farmers; it nurtures the crops and stock of rural communities; it provides recreation for our children, our friends, our families; it supports our power generation, our mines, our industry, and the plants and animals that make up ecosystems. Water is the key to development and a good quality of life in South Africa. South Africa's water belongs to its people. It is the task of the South African Government to care for this water, to seek its fair distribution, and to facilitate its wise use for, amongst other things, social and economical development. Issues such as water resource management, use, protection, water services, etc., are presently governed by a number of policies, acts and regulations. All South Africans has a responsibility regarding the management of the country's resources. The supply of water to its entire people makes it extremely important to optimise the use of this scarce source. Access to water and water availability remains a key factor in ensuring the sustainability of development in Southern Africa. The coal fired power industry is a major user of natural resources; coal for fuel and water for steam generation as well as the cooling systems. It is estimated that 1.5% of the water abstracted in South Africa is used for power generation. The power industry receives its water mainly as abstraction from surface impoundments in the form of rivers and dams. Eskom, as a strategic user of water, is mindful of the importance of water to its business, as well as the development of the country. In addition to the interests of the government as the shareholder, Eskom recognises the legitimate interests, as stakeholders, of specific government departments, employees, consumers, suppliers, investors and lenders of capital, rating agencies, the media, policy and regulatory bodies, trade unions, non-governmental groups and local communities in its affairs. Eskom needs to ensure, through an effective water management strategy, that water is used wisely and effectively and that Eskom's impact on local water resources (surface and underground) is minimised. Eskom therefore has to manage water resources in a manner that will sustain the ecological integrity, support social development and ensure economic growth. Eskom has undertaken to benchmark the power generation industry, in co-operation with the DW AF, in a project aimed at developing the principles of water conservation and water demand management. In order to effectively manage water quality and quantity at Eskom's power stations, and to show Eskom's commitment with regard to water conservation and use, Eskom has compiled its own water and environmental policies.
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Long term overheating and its effect on plant availability
- Authors: Madjoe, Sean Michael
- Date: 2015
- Subjects: Boilers - Efficiency , Coal-fired power plants , Heat - Transmission , Steam-boilers - Creep , Boilers - Testing
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56161 , uj:16338
- Description: Abstract: This mini-dissertation investigates the impact that Long Term Overheating and Creep (LTOC) has on coal fired power stations and the availability implications thereof. The need for the investigation arose from a single coal fired power station, with multiple boilers with a total generating capacity of greater than 400MW, of which LTOC is the dominant boiler tube failure mechanism. For the purposes of the mini-dissertation, the power station was simply titled Power Station X. A summary is provided of the various boiler tube failure mechanisms as well as a brief description of availability. The mini-dissertation makes use of case studies in researching the matter of LTOC. It was seen that LTOC is a global matter, which is typically seen in ageing power stations. The major discussion points arising from the mini-dissertation is that of a boiler tube failure management program as well as correctly understanding the causes of boiler tube failures. With an adequate and correctly functioning boiler tube failure management program one can reduce and manage the occurrence of boiler tube failures. The second major discussion point arising from the mini-dissertation is that of correctly understanding the contributing factors to boiler tube failures. A lot of emphasis has been placed on the actual mechanisms and identification of failures, however the contributing factors and root cause has not been thoroughly investigated. Additionally one also has to identify the various areas prone to creep and the necessary remedial and mitigating actions for the removal and or replacement of such components, while keeping in mind the financial implication thereof. The mini-dissertation concludes with possible areas of future research as well as possible remedial actions that can be taken. , M.Ing. (Engineering Management)
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- Authors: Madjoe, Sean Michael
- Date: 2015
- Subjects: Boilers - Efficiency , Coal-fired power plants , Heat - Transmission , Steam-boilers - Creep , Boilers - Testing
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56161 , uj:16338
- Description: Abstract: This mini-dissertation investigates the impact that Long Term Overheating and Creep (LTOC) has on coal fired power stations and the availability implications thereof. The need for the investigation arose from a single coal fired power station, with multiple boilers with a total generating capacity of greater than 400MW, of which LTOC is the dominant boiler tube failure mechanism. For the purposes of the mini-dissertation, the power station was simply titled Power Station X. A summary is provided of the various boiler tube failure mechanisms as well as a brief description of availability. The mini-dissertation makes use of case studies in researching the matter of LTOC. It was seen that LTOC is a global matter, which is typically seen in ageing power stations. The major discussion points arising from the mini-dissertation is that of a boiler tube failure management program as well as correctly understanding the causes of boiler tube failures. With an adequate and correctly functioning boiler tube failure management program one can reduce and manage the occurrence of boiler tube failures. The second major discussion point arising from the mini-dissertation is that of correctly understanding the contributing factors to boiler tube failures. A lot of emphasis has been placed on the actual mechanisms and identification of failures, however the contributing factors and root cause has not been thoroughly investigated. Additionally one also has to identify the various areas prone to creep and the necessary remedial and mitigating actions for the removal and or replacement of such components, while keeping in mind the financial implication thereof. The mini-dissertation concludes with possible areas of future research as well as possible remedial actions that can be taken. , M.Ing. (Engineering Management)
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Experimental and modelling studies on the interactions of metals and natural organic matter in cooling water at coal powergeneration plants
- Authors: Bosire, Geoffrey Orina
- Date: 2015
- Subjects: Eskom (Firm) , Chromatographic analysis , Photooxidative stress , Coal-fired power plants , Industrial water supply
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/225032 , uj:22719
- Description: Abstract: Eskom, the chief power generating and supply company in South Africa, has power stations that are mainly coal-fired. The surface water used in the condenser tubes for cooling purposes at these stations is rich in dissolved organic and inorganic compounds. Due to the relatively high concentration of alkaline earth metals (notably Ca and Mg) in the water, super-saturation of mineral phases that are responsible for scale formation occurs in a range of physico-chemical parameters (such as pH, ionic strength and temperature). Natural organic matter (NOM) in aquatic environments influences the speciation and mobility of metals, and is available in high concentrations in different fractions. The humic substances fraction, for instance, has concentrations ranging 10-200 mg/L. Studies in this thesis typify the characteristics and role of NOM with respect to complexation to metal cations. This complexation is understood to minimize scaling potential at the Lethabo and Kriel power stations, as archetypical power generating stations in South Africa. Furthermore, PHREEQC based simulations using the modified Tipping and Hurley database with Windermere’s Humic Acid Model (T_H-WHAM) were used to speciate and quantify complexation outputs. Conventional NOM characterization techniques such as ultra-violet (UV) analysis, total and dissolved organic carbon (TOC/DOC) analysis, specific ultra violet absorbance (SUVA) measurements have been found lacking in terms of analysis time and robustness. As an alternative, detailed characterization of NOM compounds in raw and cooling water (extracted by solid phase extraction) was achieved by the use of liquid chromatography-organic carbon detection-organic nitrogen (LC-OCD-OND), fluorescence excitation emission matrices (FEEM) and 2 dimensional gas x gas chromatography with a time-of-flight mass spectrometer (GC x GC-TOFMS). Organic compounds with different molecular weights were characterized i.e. those with >600 g by LC-OCD-OND and <600 g by GC x GC-TOFMS). Fluorescing/chromophoric NOM compounds determined by FEEM were mainly humic substances. The fractions obtained by GC x GC-TOFMS (such as aliphatic and aromatic), highly depended on pre... , Ph.D. (Chemistry)
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- Authors: Bosire, Geoffrey Orina
- Date: 2015
- Subjects: Eskom (Firm) , Chromatographic analysis , Photooxidative stress , Coal-fired power plants , Industrial water supply
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/225032 , uj:22719
- Description: Abstract: Eskom, the chief power generating and supply company in South Africa, has power stations that are mainly coal-fired. The surface water used in the condenser tubes for cooling purposes at these stations is rich in dissolved organic and inorganic compounds. Due to the relatively high concentration of alkaline earth metals (notably Ca and Mg) in the water, super-saturation of mineral phases that are responsible for scale formation occurs in a range of physico-chemical parameters (such as pH, ionic strength and temperature). Natural organic matter (NOM) in aquatic environments influences the speciation and mobility of metals, and is available in high concentrations in different fractions. The humic substances fraction, for instance, has concentrations ranging 10-200 mg/L. Studies in this thesis typify the characteristics and role of NOM with respect to complexation to metal cations. This complexation is understood to minimize scaling potential at the Lethabo and Kriel power stations, as archetypical power generating stations in South Africa. Furthermore, PHREEQC based simulations using the modified Tipping and Hurley database with Windermere’s Humic Acid Model (T_H-WHAM) were used to speciate and quantify complexation outputs. Conventional NOM characterization techniques such as ultra-violet (UV) analysis, total and dissolved organic carbon (TOC/DOC) analysis, specific ultra violet absorbance (SUVA) measurements have been found lacking in terms of analysis time and robustness. As an alternative, detailed characterization of NOM compounds in raw and cooling water (extracted by solid phase extraction) was achieved by the use of liquid chromatography-organic carbon detection-organic nitrogen (LC-OCD-OND), fluorescence excitation emission matrices (FEEM) and 2 dimensional gas x gas chromatography with a time-of-flight mass spectrometer (GC x GC-TOFMS). Organic compounds with different molecular weights were characterized i.e. those with >600 g by LC-OCD-OND and <600 g by GC x GC-TOFMS). Fluorescing/chromophoric NOM compounds determined by FEEM were mainly humic substances. The fractions obtained by GC x GC-TOFMS (such as aliphatic and aromatic), highly depended on pre... , Ph.D. (Chemistry)
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Coal pulveriser maintenance performance enhancement through the application of a combination of new technologies
- Authors: Holtshauzen, Gerhard
- Date: 2011-06-22T10:42:17Z
- Subjects: Coal pulveriser , Milling machinery , Coal-fired power plants , Mechanical engineering
- Type: Thesis
- Identifier: uj:7109 , http://hdl.handle.net/10210/3703
- Description: M.Ing. , The dissertation is an investigation on the implementation of new technologies (five off) in a coal pulverising with main aim to optimise mill maintenance interventions. The technologies in question are: • Stationary air throat replaced with a rotating throat assembly. • Hydro-pneumatic mill loading cylinders replaced with airbags. • Classifier cone modification. • Introduction of triton material for the mill spider guide plates. • High chrome mill grinding balls. Every maintenance intervention, even if planned, negatively affects a plant’s availability and reliability. A Babcock and Wilcox (B&W) at Kriel power station (ESKOM) was used for the testing of the mentioned technologies. The mill model/size is a B&W 10.8E mill. The aim of the introduction of new technology on a mill is to optimise the period between required maintenance activities. A higher availability will assist in achieving good plant maintenance performance indicators. It needs to be noted that the dissertation focussed on the financial and technical parameters of a specific modification. This in an effort to increase uptime and reduce costs as part of a business drive for bigger profit margins. The new technologies tested were thus evaluated from a technical and financial point of view. Each technology was implemented at different time periods and nowhere was any tests performed in parallel on a single mill. To get approval from an investment committee for release of money for tests/modifications, technical and financial assumptions need to be made regarding the performance parameters of the modification/change. Once a modification is being tested, actual plant data can be used as inputs into the execution phase of the modification as assumptions can be replaced with test data. A financial model was developed to “test” the financial feasibility of the proposed changes/modifications. With new technology successful implemented in the plant the current maintenance strategies for maintenance interventions can be re-evaluated as the proposed modifications removed historic barriers that determined the current used based maintenance intervals. An example is where a mill is taken from service to replace or repair the stationary air throat (typically every 5 000 operating hours). With the newly applied technology (rotating throat assemblies), there is no need for maintenance interventions every 5 000hrs as a rotating throat assembly can run without major interventions for 60 000hrs.
- Full Text:
- Authors: Holtshauzen, Gerhard
- Date: 2011-06-22T10:42:17Z
- Subjects: Coal pulveriser , Milling machinery , Coal-fired power plants , Mechanical engineering
- Type: Thesis
- Identifier: uj:7109 , http://hdl.handle.net/10210/3703
- Description: M.Ing. , The dissertation is an investigation on the implementation of new technologies (five off) in a coal pulverising with main aim to optimise mill maintenance interventions. The technologies in question are: • Stationary air throat replaced with a rotating throat assembly. • Hydro-pneumatic mill loading cylinders replaced with airbags. • Classifier cone modification. • Introduction of triton material for the mill spider guide plates. • High chrome mill grinding balls. Every maintenance intervention, even if planned, negatively affects a plant’s availability and reliability. A Babcock and Wilcox (B&W) at Kriel power station (ESKOM) was used for the testing of the mentioned technologies. The mill model/size is a B&W 10.8E mill. The aim of the introduction of new technology on a mill is to optimise the period between required maintenance activities. A higher availability will assist in achieving good plant maintenance performance indicators. It needs to be noted that the dissertation focussed on the financial and technical parameters of a specific modification. This in an effort to increase uptime and reduce costs as part of a business drive for bigger profit margins. The new technologies tested were thus evaluated from a technical and financial point of view. Each technology was implemented at different time periods and nowhere was any tests performed in parallel on a single mill. To get approval from an investment committee for release of money for tests/modifications, technical and financial assumptions need to be made regarding the performance parameters of the modification/change. Once a modification is being tested, actual plant data can be used as inputs into the execution phase of the modification as assumptions can be replaced with test data. A financial model was developed to “test” the financial feasibility of the proposed changes/modifications. With new technology successful implemented in the plant the current maintenance strategies for maintenance interventions can be re-evaluated as the proposed modifications removed historic barriers that determined the current used based maintenance intervals. An example is where a mill is taken from service to replace or repair the stationary air throat (typically every 5 000 operating hours). With the newly applied technology (rotating throat assemblies), there is no need for maintenance interventions every 5 000hrs as a rotating throat assembly can run without major interventions for 60 000hrs.
- Full Text:
The energy and environmental impacts of a coal and Bagasse-fired power plant in the sugar industry
- Authors: Mbohwa, Charles
- Date: 2009
- Subjects: Coal-fired power plants , Bagasse-fired power plants , Sugar trade - South Africa
- Type: Article
- Identifier: uj:5187 , http://hdl.handle.net/10210/14430
- Description: This paper presents a thermodynamic model of a proposed firm power plant co-fired with bagasse and coal under South African conditions. It proposes the energy conversion for a 2.5 million tonnes of sugarcane per year sugar factory and demonstrates that a power plant of up to 120 MW can be supported by such a facility. Carbon emissions are quantified and compared to a 120 MW coal only power plant, to establish expected environmental benefits. It demonstrates the technical feasibility of power plant development in the South African sugar industry and contributes to informed decisions on partly renewable energy power plants.
- Full Text:
- Authors: Mbohwa, Charles
- Date: 2009
- Subjects: Coal-fired power plants , Bagasse-fired power plants , Sugar trade - South Africa
- Type: Article
- Identifier: uj:5187 , http://hdl.handle.net/10210/14430
- Description: This paper presents a thermodynamic model of a proposed firm power plant co-fired with bagasse and coal under South African conditions. It proposes the energy conversion for a 2.5 million tonnes of sugarcane per year sugar factory and demonstrates that a power plant of up to 120 MW can be supported by such a facility. Carbon emissions are quantified and compared to a 120 MW coal only power plant, to establish expected environmental benefits. It demonstrates the technical feasibility of power plant development in the South African sugar industry and contributes to informed decisions on partly renewable energy power plants.
- Full Text:
South African coal and its abrasiveness index determination : an account of challenges
- Tshiongo, N., Mulaba-Bafubiandi, A.
- Authors: Tshiongo, N. , Mulaba-Bafubiandi, A.
- Date: 2013
- Subjects: Coal-fired power plants , Electric power production - South Africa
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15508 , uj:15669 , Tshiongo, N. & Mulaba-Bafubiandi, N. 2013. South African coal and its abrasiveness index determination : an account of challenges. In: Proceeding of the 23rd International mining congress and exhibition of Turkey (IMCET), Antalya, Turkey, 2013 April 16-19.
- Description: Abstract: Industry end users of coal like electricity generating stations have specifications on coal required in terms of reactive, chemical and physical properties; this includes the ash content, moisture, composition, hardgrove grindability index and abrasiveness index amongst many other properties. These properties affect each other including the overall coal properties and performance required during its specified usage. Some South African coals are known to be very abrasive, this causes operational challenges during the electricity generation combustion process as the coal abrades the plant equipment at a faster rate. Various South African coal samples were tested for abrasiveness index using the Yancey, Geer and Price (YGP) method. Results from these tests showed a lack of repeatability and reproducibility on the abrasiveness index values of coal samples. This lack of repeatability and reproducibility was observed in all coal samples tested. The same was found when either the same sample was tested in different laboratories or even when a mother sample was divided and tested repeatedly in one laboratory. Proximate and Ultimate analysis were conducted on the same South African coal samples for coal characterisation and classification. The size of the analysed sample; the size and shape, the degree of liberation of the abrasive coal component, and the interface between the abrasive component of coal and the blade surface are additional contributing factors. This study gives an account of challenges experienced and observed during the abrasiveness index determination of different South African coal samples. An attempt to holistically integrate the impact of main coal components contributing to the abrasiveness of coal will be presented.
- Full Text: false
- Authors: Tshiongo, N. , Mulaba-Bafubiandi, A.
- Date: 2013
- Subjects: Coal-fired power plants , Electric power production - South Africa
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15508 , uj:15669 , Tshiongo, N. & Mulaba-Bafubiandi, N. 2013. South African coal and its abrasiveness index determination : an account of challenges. In: Proceeding of the 23rd International mining congress and exhibition of Turkey (IMCET), Antalya, Turkey, 2013 April 16-19.
- Description: Abstract: Industry end users of coal like electricity generating stations have specifications on coal required in terms of reactive, chemical and physical properties; this includes the ash content, moisture, composition, hardgrove grindability index and abrasiveness index amongst many other properties. These properties affect each other including the overall coal properties and performance required during its specified usage. Some South African coals are known to be very abrasive, this causes operational challenges during the electricity generation combustion process as the coal abrades the plant equipment at a faster rate. Various South African coal samples were tested for abrasiveness index using the Yancey, Geer and Price (YGP) method. Results from these tests showed a lack of repeatability and reproducibility on the abrasiveness index values of coal samples. This lack of repeatability and reproducibility was observed in all coal samples tested. The same was found when either the same sample was tested in different laboratories or even when a mother sample was divided and tested repeatedly in one laboratory. Proximate and Ultimate analysis were conducted on the same South African coal samples for coal characterisation and classification. The size of the analysed sample; the size and shape, the degree of liberation of the abrasive coal component, and the interface between the abrasive component of coal and the blade surface are additional contributing factors. This study gives an account of challenges experienced and observed during the abrasiveness index determination of different South African coal samples. An attempt to holistically integrate the impact of main coal components contributing to the abrasiveness of coal will be presented.
- Full Text: false
A comparative environmental analysis of fossil fuel electricity generation options for South Africa
- Authors: Govender, Indran
- Date: 2009-02-05T07:10:25Z
- Subjects: Environmental impact analysis , Coal-fired power plants , Gas-turbine power-plants , Fossil fuel power plants , Integrated gasification combined cycle power plants
- Type: Thesis
- Identifier: uj:8074 , http://hdl.handle.net/10210/2004
- Description: M.Sc. , The increased demand for electricity in South Africa is expected to exceed supply between 2004 and 2007. Electricity supply options in the country would be further complicated by the fact that older power stations would reach the end of their design life beyond the year 2025. In light of this and considering the long lead times required for the commissioning of new plants, new power supply options need to be proactively investigated. The environmental impacts associated with coal-fired generation of electricity have resulted in increased global concern over the past decade. To reduce these impacts, new technologies have been identified to help provide electricity from fossil fuels. The alternatives considered are gas-fired generation technologies and the Integrated Gasification Combined Cycle (IGCC). This study attempts to document and understand the environmental aspects related to gas-fired and IGCC electricity generation and evaluate their advantages in comparison to conventional pulverised coal fired power generation. The options that could be utilised to make fossil fuel electricity generation more environmentally friendly, whilst remaining economically feasible, were also evaluated. Gas-fired electricity generation is extremely successful as electricity generation systems in the world due to inherently low levels of emissions, high efficiencies, fuel flexibility and reduced demand on finite resources. Associated benefits of a Combined Cycle Gas Turbine (CCGT) are lower operating costs due to the reduced water consumption, smaller equipment size and a reduction in the wastewater that has to be treated before being returned to the environment. A CCGT plant requires less cooling water and can be located on a smaller area than a conventional Pulverised Fuel (PF) power station of the same capacity. All these factors reduce the burden on the environment. A CCGT also employs processes that utilises the energy of the fuel more efficiently, with the current efficiencies approaching 60%. Instead of simply being discharged into the atmosphere, the gas turbines’ exhaust gas heat is used to produce additional output in combination with a Heat Recovery Steam Generator (HRSG) and a steam turbine. Furthermore, as finite resources become increasingly scarce and energy has to be used as wisely as possible, generating electricity economically and in an ecologically sound manner is of the utmost importance. The clean, reliable operation of gas-fired generation systems with significantly reduced noise levels and their compact design makes their operation feasible in heavily populated areas, where electricity is needed most. At the same time, energy can be consumed in whatever form needed, i.e. as electricity, heat or steam. The dependence of the South African economy on cheap coal ensures that it will remain a vital component of future electricity generation options in the country. This dominance of coal-fired generation in the country is responsible for South Africa’s title as the largest generator of carbon dioxide (CO2) emissions on the continent and the country could possibly be requested to reduce its CO2 emissions at the next international meeting of signatories to the Kyoto Protocol. Carbon dioxide emissions can be reduced by utilising gas-fired generation technologies. However, the uncertainty and costs associated with natural gas in South Africa hampers the implementation of this technology. There are currently a number of initiatives surrounding the development of natural gas in the country, viz. the Pande and Temane projects in Mozambique and the Kudu project in Namibia, and this is likely to positively influence the choice of fuel utilised for electricity generation in the future. The economic viability of these projects would be further enhanced through the obtaining of Clean Development Mechanism (CDM) credits for greenhouse gases (GHG) emissions reduction. Alternatively, more efficient methods of generating electricity from coal must be developed and implemented. IGCC is capable of achieving this because of the high efficiencies associated with the combined cycle component of the technology. These higher efficiencies result in reduced emissions to the atmosphere for an equivalent unit of electricity generated from a PF station. An IGCC system can be successful in South Africa in that it combines the benefits of utilising gas-fired electricity generation systems whilst utilising economically feasible fuel, i.e. coal. IGCC systems can economically meet strict air pollution emission standards, produce water effluent within environmental limits, produce an environmentally benign slag, with good potential as a saleable by-product, and recover a valuable sulphur commodity by-product. Life-cycle analyses performed on IGCC power plants have identified CO2 release and natural resource depletion as their most significant positive lifecycle impacts, which testifies to the IGCC’s low pollutant releases and benign by-products. Recent studies have also shown that these plants can be built to efficiently accommodate future CO2 capture technology that could further reduce environmental impacts. The outstanding environmental performance of IGCC makes it an excellent technology for the clean production of electricity. IGCC systems also provide flexibility in the production of a wide range of products including electricity, fuels, chemicals, hydrogen, and steam, while utilizing low-cost, widely available feedstocks. Coal-based gasification systems provide an energy production alternative that is more efficient and environmentally friendly than competing coalfuelled technologies. The obstacle to the large-scale implementation of this technology in the country is the high costs associated with the technology. CDM credits and by-products sales could possible enhance the viability of implementing these technologies in South Africa.
- Full Text:
- Authors: Govender, Indran
- Date: 2009-02-05T07:10:25Z
- Subjects: Environmental impact analysis , Coal-fired power plants , Gas-turbine power-plants , Fossil fuel power plants , Integrated gasification combined cycle power plants
- Type: Thesis
- Identifier: uj:8074 , http://hdl.handle.net/10210/2004
- Description: M.Sc. , The increased demand for electricity in South Africa is expected to exceed supply between 2004 and 2007. Electricity supply options in the country would be further complicated by the fact that older power stations would reach the end of their design life beyond the year 2025. In light of this and considering the long lead times required for the commissioning of new plants, new power supply options need to be proactively investigated. The environmental impacts associated with coal-fired generation of electricity have resulted in increased global concern over the past decade. To reduce these impacts, new technologies have been identified to help provide electricity from fossil fuels. The alternatives considered are gas-fired generation technologies and the Integrated Gasification Combined Cycle (IGCC). This study attempts to document and understand the environmental aspects related to gas-fired and IGCC electricity generation and evaluate their advantages in comparison to conventional pulverised coal fired power generation. The options that could be utilised to make fossil fuel electricity generation more environmentally friendly, whilst remaining economically feasible, were also evaluated. Gas-fired electricity generation is extremely successful as electricity generation systems in the world due to inherently low levels of emissions, high efficiencies, fuel flexibility and reduced demand on finite resources. Associated benefits of a Combined Cycle Gas Turbine (CCGT) are lower operating costs due to the reduced water consumption, smaller equipment size and a reduction in the wastewater that has to be treated before being returned to the environment. A CCGT plant requires less cooling water and can be located on a smaller area than a conventional Pulverised Fuel (PF) power station of the same capacity. All these factors reduce the burden on the environment. A CCGT also employs processes that utilises the energy of the fuel more efficiently, with the current efficiencies approaching 60%. Instead of simply being discharged into the atmosphere, the gas turbines’ exhaust gas heat is used to produce additional output in combination with a Heat Recovery Steam Generator (HRSG) and a steam turbine. Furthermore, as finite resources become increasingly scarce and energy has to be used as wisely as possible, generating electricity economically and in an ecologically sound manner is of the utmost importance. The clean, reliable operation of gas-fired generation systems with significantly reduced noise levels and their compact design makes their operation feasible in heavily populated areas, where electricity is needed most. At the same time, energy can be consumed in whatever form needed, i.e. as electricity, heat or steam. The dependence of the South African economy on cheap coal ensures that it will remain a vital component of future electricity generation options in the country. This dominance of coal-fired generation in the country is responsible for South Africa’s title as the largest generator of carbon dioxide (CO2) emissions on the continent and the country could possibly be requested to reduce its CO2 emissions at the next international meeting of signatories to the Kyoto Protocol. Carbon dioxide emissions can be reduced by utilising gas-fired generation technologies. However, the uncertainty and costs associated with natural gas in South Africa hampers the implementation of this technology. There are currently a number of initiatives surrounding the development of natural gas in the country, viz. the Pande and Temane projects in Mozambique and the Kudu project in Namibia, and this is likely to positively influence the choice of fuel utilised for electricity generation in the future. The economic viability of these projects would be further enhanced through the obtaining of Clean Development Mechanism (CDM) credits for greenhouse gases (GHG) emissions reduction. Alternatively, more efficient methods of generating electricity from coal must be developed and implemented. IGCC is capable of achieving this because of the high efficiencies associated with the combined cycle component of the technology. These higher efficiencies result in reduced emissions to the atmosphere for an equivalent unit of electricity generated from a PF station. An IGCC system can be successful in South Africa in that it combines the benefits of utilising gas-fired electricity generation systems whilst utilising economically feasible fuel, i.e. coal. IGCC systems can economically meet strict air pollution emission standards, produce water effluent within environmental limits, produce an environmentally benign slag, with good potential as a saleable by-product, and recover a valuable sulphur commodity by-product. Life-cycle analyses performed on IGCC power plants have identified CO2 release and natural resource depletion as their most significant positive lifecycle impacts, which testifies to the IGCC’s low pollutant releases and benign by-products. Recent studies have also shown that these plants can be built to efficiently accommodate future CO2 capture technology that could further reduce environmental impacts. The outstanding environmental performance of IGCC makes it an excellent technology for the clean production of electricity. IGCC systems also provide flexibility in the production of a wide range of products including electricity, fuels, chemicals, hydrogen, and steam, while utilizing low-cost, widely available feedstocks. Coal-based gasification systems provide an energy production alternative that is more efficient and environmentally friendly than competing coalfuelled technologies. The obstacle to the large-scale implementation of this technology in the country is the high costs associated with the technology. CDM credits and by-products sales could possible enhance the viability of implementing these technologies in South Africa.
- Full Text:
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