Potential and technical basis for utilising coal beneficiation discards in power generation by applying circulating fluidised bed boilers
- Belaid, Mohamed, Falcon, Rosemary, Vainikka, Pasi, Patsa, Kamohelo V.
- Authors: Belaid, Mohamed , Falcon, Rosemary , Vainikka, Pasi , Patsa, Kamohelo V.
- Date: 2013
- Subjects: Coal , Discard coal
- Type: Article
- Identifier: uj:4977 , http://hdl.handle.net/10210/13078
- Description: Coal continues to remain South Africa’s prime energy source with coal fired power generation by ESKOM (62 %) and gasification by SASOL (23 %) leading local coal consumption. Beneficiated coal is also exported (70 million tonnes) while raw sized coal is also consumed for cooking and heating in South Africa’s townships. Discard coal is currently being produced at annual rates in excess of 60 million tonne per annum. This is estimated to have already accumulated to more than 1-billion tonnes. Discard coal is a major concern to the department of mineral and energy regarding the potential environmental impact in the future. It should also be seen as a major resource that could provide economic opportunity. The purpose of this paper is to estimate the production and reservoir volumes of SA coal discards and their technical and economic potential application in large scale power generation through CFB combustion. It was found that whilst discard is a poor material, its varying range in heating value and current production rate makes it a potentially viable material for beneficiation towards electricity generation. It’s been found that beneficiating discard coal could come with some challenges e.g initial costs, but on the other hand it could present techno economic opportunities e.g harnessing new technologies to create employment...
- Full Text:
- Authors: Belaid, Mohamed , Falcon, Rosemary , Vainikka, Pasi , Patsa, Kamohelo V.
- Date: 2013
- Subjects: Coal , Discard coal
- Type: Article
- Identifier: uj:4977 , http://hdl.handle.net/10210/13078
- Description: Coal continues to remain South Africa’s prime energy source with coal fired power generation by ESKOM (62 %) and gasification by SASOL (23 %) leading local coal consumption. Beneficiated coal is also exported (70 million tonnes) while raw sized coal is also consumed for cooking and heating in South Africa’s townships. Discard coal is currently being produced at annual rates in excess of 60 million tonne per annum. This is estimated to have already accumulated to more than 1-billion tonnes. Discard coal is a major concern to the department of mineral and energy regarding the potential environmental impact in the future. It should also be seen as a major resource that could provide economic opportunity. The purpose of this paper is to estimate the production and reservoir volumes of SA coal discards and their technical and economic potential application in large scale power generation through CFB combustion. It was found that whilst discard is a poor material, its varying range in heating value and current production rate makes it a potentially viable material for beneficiation towards electricity generation. It’s been found that beneficiating discard coal could come with some challenges e.g initial costs, but on the other hand it could present techno economic opportunities e.g harnessing new technologies to create employment...
- Full Text:
Sustainable management in the synfuels sector in South Africa
- Maimbo, T. T., Mbohwa, Charles, Mutingi, M.
- Authors: Maimbo, T. T. , Mbohwa, Charles , Mutingi, M.
- Date: 2012
- Subjects: Synthetic fuels , Sustainable management , Coal
- Type: Article
- Identifier: uj:6024 , ISBN 978-09855497-0-1 , http://hdl.handle.net/10210/10044
- Description: The debate about the decline in petroleum reserves, the worries over peak oil, the Middle East tension and oil price speculation challenges has made it important to focus on sustainable management and utilization of alternative fuels. The use of alternative fuels to supply the energy needs of the world is not a new concept. This paper reviews coal as a recoverable hydrocarbon-rich resource found in abundant quantities in South Africa (SA). This study review shows that coal will continue to provide a key for the unlocking many of the future global requirements for high-quality energy and chemical building blocks. The historical premise that coal is a dirty fuel is being countered with the continued development and operation of technology to significantly reduce the environmental footprint of coal-sourced energy is investigated. Conclusions are drawn. Firstly, the study brings to our attention that technology is available and is continually being improved to turn coal into synthetic natural gas, transportation fuels, chemicals, chemical intermediates and hydrogen in a way that reduces GHG emissions. Secondly, the study shows that there is a viable coal-to-liquids (CTL) industry in South Africa supplying high-quality middle distillates, in particular diesel fuel, jet kerosene and middle distillate blend stocks. The CTL economics, the potential role of the government and how large-scale development of this industry might impact the environment is analysed on sustainable management.
- Full Text:
- Authors: Maimbo, T. T. , Mbohwa, Charles , Mutingi, M.
- Date: 2012
- Subjects: Synthetic fuels , Sustainable management , Coal
- Type: Article
- Identifier: uj:6024 , ISBN 978-09855497-0-1 , http://hdl.handle.net/10210/10044
- Description: The debate about the decline in petroleum reserves, the worries over peak oil, the Middle East tension and oil price speculation challenges has made it important to focus on sustainable management and utilization of alternative fuels. The use of alternative fuels to supply the energy needs of the world is not a new concept. This paper reviews coal as a recoverable hydrocarbon-rich resource found in abundant quantities in South Africa (SA). This study review shows that coal will continue to provide a key for the unlocking many of the future global requirements for high-quality energy and chemical building blocks. The historical premise that coal is a dirty fuel is being countered with the continued development and operation of technology to significantly reduce the environmental footprint of coal-sourced energy is investigated. Conclusions are drawn. Firstly, the study brings to our attention that technology is available and is continually being improved to turn coal into synthetic natural gas, transportation fuels, chemicals, chemical intermediates and hydrogen in a way that reduces GHG emissions. Secondly, the study shows that there is a viable coal-to-liquids (CTL) industry in South Africa supplying high-quality middle distillates, in particular diesel fuel, jet kerosene and middle distillate blend stocks. The CTL economics, the potential role of the government and how large-scale development of this industry might impact the environment is analysed on sustainable management.
- Full Text:
Effect of blending coal with torrefied biomass for possible application in energy production
- Authors: Mamvura, T. , Muzenda, E.
- Date: 2016
- Subjects: Coal , Biomass , Blending , Torrefaction
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/93696 , uj:20382 , Citation: Mamvura, T. & Muzenda, E. 2016. Effect of blending coal with torrefied biomass for possible application in energy production.
- Description: Abstract: Emissions of greenhouse gases mostly from fossil fuels are responsible for global warming and climatic changes. This has led to research in bioenergy to reduce greenhouse emissions because bioenergy is part of the carbon cycle, and can only emit greenhouse gases that are part of the carbon cycle. The drawback is its low calorific value when it is in its raw form. Torrefaction improves its energy content to values that are comparable to coal. In this study, marula seeds and blue gum wood, two of South Africa most abundant biomass, were blended with coal both raw and torrefied to see the impact of the torrefaction process on energy density. Blending was done at different ratios to see the optimum results. Results showed that highest calorific value was obtained at 100% marula seeds and 0 % coal, and it was recommended for further studies. Blue gum wood due to its high moisture had slightly higher heating value than the reference coal but from an economical point of view it was not attractive for further studies. This showed the significance of the torrefaction process in increasing heating value of selected biomass in the hope of reducing effects of greenhouse gas emissions.
- Full Text:
- Authors: Mamvura, T. , Muzenda, E.
- Date: 2016
- Subjects: Coal , Biomass , Blending , Torrefaction
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/93696 , uj:20382 , Citation: Mamvura, T. & Muzenda, E. 2016. Effect of blending coal with torrefied biomass for possible application in energy production.
- Description: Abstract: Emissions of greenhouse gases mostly from fossil fuels are responsible for global warming and climatic changes. This has led to research in bioenergy to reduce greenhouse emissions because bioenergy is part of the carbon cycle, and can only emit greenhouse gases that are part of the carbon cycle. The drawback is its low calorific value when it is in its raw form. Torrefaction improves its energy content to values that are comparable to coal. In this study, marula seeds and blue gum wood, two of South Africa most abundant biomass, were blended with coal both raw and torrefied to see the impact of the torrefaction process on energy density. Blending was done at different ratios to see the optimum results. Results showed that highest calorific value was obtained at 100% marula seeds and 0 % coal, and it was recommended for further studies. Blue gum wood due to its high moisture had slightly higher heating value than the reference coal but from an economical point of view it was not attractive for further studies. This showed the significance of the torrefaction process in increasing heating value of selected biomass in the hope of reducing effects of greenhouse gas emissions.
- Full Text:
Coal combustion models: a review
- Marangwanda, G. T., Madyira, D. M., Babarinde, T. O.
- Authors: Marangwanda, G. T. , Madyira, D. M. , Babarinde, T. O.
- Date: 2019
- Subjects: Coal , Combusion , Computational fluid dynamics
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/406660 , uj:34199 , Citation: Marangwanda, G.T., Madyira, D.M., Babarinde, T.O. 2019 : Coal combustion models: a review. DOI: 10.1088/1742-6596/1378/3/032070.
- Description: Abstract : Computational Fluid Dynamics has been used for optimisation of industrial applications with some level of success. The modest accuracy provided by some of the combustion models in use has left some room for research and improvement. Coal is presented as a fuel with complex chemical properties due to its fossil fuel nature. The devolatilization process of coal is investigated with special attention to the best models that can handle heavy and light volatiles found in coal. The heterogenous char combustion is also presented paying attention to the nature of the char particle during the combustion process. The other processes such as drying, homogenous volatile combustion, radiation models, particle tracking models and turbulent models are investigated in a general manner as they rarely vary with the type of fuel being investigated. A summary of the industrial applications that have successfully utilised the CFD models for optimisation of coal combustion are presented thus helping in drawing the final conclusion.
- Full Text:
- Authors: Marangwanda, G. T. , Madyira, D. M. , Babarinde, T. O.
- Date: 2019
- Subjects: Coal , Combusion , Computational fluid dynamics
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/406660 , uj:34199 , Citation: Marangwanda, G.T., Madyira, D.M., Babarinde, T.O. 2019 : Coal combustion models: a review. DOI: 10.1088/1742-6596/1378/3/032070.
- Description: Abstract : Computational Fluid Dynamics has been used for optimisation of industrial applications with some level of success. The modest accuracy provided by some of the combustion models in use has left some room for research and improvement. Coal is presented as a fuel with complex chemical properties due to its fossil fuel nature. The devolatilization process of coal is investigated with special attention to the best models that can handle heavy and light volatiles found in coal. The heterogenous char combustion is also presented paying attention to the nature of the char particle during the combustion process. The other processes such as drying, homogenous volatile combustion, radiation models, particle tracking models and turbulent models are investigated in a general manner as they rarely vary with the type of fuel being investigated. A summary of the industrial applications that have successfully utilised the CFD models for optimisation of coal combustion are presented thus helping in drawing the final conclusion.
- Full Text:
Emissions of tar balls from domestic coal burning braziers
- Masekameni, Daniel, Makonese, Tafadzwa
- Authors: Masekameni, Daniel , Makonese, Tafadzwa
- Date: 2018
- Subjects: Coal , imbaula , Combustion phase
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273116 , uj:29090 , Citation: Masekameni, D. & Makonese, T. 2018. Emissions of tar balls from domestic coal burning braziers.
- Description: Abstract: On the central-plateau of the South African Highveld, domestic coal combustion is associated with the release of carbonaceous aerosols often produced as dendritic carbonaceous particles and tar balls. However, very few studies have been conducted to validate this contribution. Combustion of coal in low-income settlements is done using self-constructed devices (predominantly braziers) known as imbaulas. Combustion characteristics in these devices are influenced by fire ignition methods. The most common ignition method in South African Highveld areas is the bottom-lit updraft (BLUD) relative to the less favoured Top lit-updraft (TLUD) ignition technique. Aerosols samples were collected using Nucleopore filters combustion phases (ignition and pyrolysis). The JSM 5800LV SEM at the University of Pretoria and the Vega3 LM at the University of Johannesburg were used to observe particle morphologies from coal-burning fires. Both instruments were equipped with energy dispersive spectroscopy (EDS), which provides the possibility to analyse particle chemical compositions. Tar balls were identified in both ignition methods (BLUD and TLUD) and in pyrolysis (stage I and II). When sampling close to the fires (at ignition and pyrolysis stage I), the filter material rapidly clogged and a continuous layer of liquid/ tarry substance coalesced and covered the entire filter membrane, with some pores completely closed. At the 5 m exit point, micrographs showed distinct particles morphologies, including giant spherical organic particles that had condensed as the exhaust stream cooled. Perfectly spherical giant tar balls were observed in ageing smoke from smouldering combustion conditions typical of poorly ventilated BLUD fires. The spherical tar ball particles were found as individual spherical particles and as aggregates forming diffusion accretion chains. It is hypothesised that spherical organic particles may have been formed by the ejection of liquid tar droplets (pyrolysis stage I products of coal burning) from the pores of the burning coal, followed by rapid thermal transformation upon passing through the flame or glow zone of the fire.
- Full Text:
- Authors: Masekameni, Daniel , Makonese, Tafadzwa
- Date: 2018
- Subjects: Coal , imbaula , Combustion phase
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273116 , uj:29090 , Citation: Masekameni, D. & Makonese, T. 2018. Emissions of tar balls from domestic coal burning braziers.
- Description: Abstract: On the central-plateau of the South African Highveld, domestic coal combustion is associated with the release of carbonaceous aerosols often produced as dendritic carbonaceous particles and tar balls. However, very few studies have been conducted to validate this contribution. Combustion of coal in low-income settlements is done using self-constructed devices (predominantly braziers) known as imbaulas. Combustion characteristics in these devices are influenced by fire ignition methods. The most common ignition method in South African Highveld areas is the bottom-lit updraft (BLUD) relative to the less favoured Top lit-updraft (TLUD) ignition technique. Aerosols samples were collected using Nucleopore filters combustion phases (ignition and pyrolysis). The JSM 5800LV SEM at the University of Pretoria and the Vega3 LM at the University of Johannesburg were used to observe particle morphologies from coal-burning fires. Both instruments were equipped with energy dispersive spectroscopy (EDS), which provides the possibility to analyse particle chemical compositions. Tar balls were identified in both ignition methods (BLUD and TLUD) and in pyrolysis (stage I and II). When sampling close to the fires (at ignition and pyrolysis stage I), the filter material rapidly clogged and a continuous layer of liquid/ tarry substance coalesced and covered the entire filter membrane, with some pores completely closed. At the 5 m exit point, micrographs showed distinct particles morphologies, including giant spherical organic particles that had condensed as the exhaust stream cooled. Perfectly spherical giant tar balls were observed in ageing smoke from smouldering combustion conditions typical of poorly ventilated BLUD fires. The spherical tar ball particles were found as individual spherical particles and as aggregates forming diffusion accretion chains. It is hypothesised that spherical organic particles may have been formed by the ejection of liquid tar droplets (pyrolysis stage I products of coal burning) from the pores of the burning coal, followed by rapid thermal transformation upon passing through the flame or glow zone of the fire.
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Char production through the co-pyrolysis of coal and biomass in a fixed FED reactor
- Motlhatlhedi, T. J., Muzenda, E., Mamvura, T. A.
- Authors: Motlhatlhedi, T. J. , Muzenda, E. , Mamvura, T. A.
- Date: 2020
- Subjects: Cow dung , Char , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/461807 , uj:41146 , Citation: Motlhatlhedi, T.J., Muzenda, E. & Mamvura, T.A. 2020. Char production through the co-pyrolysis of coal and biomass in a fixed FED reactor.
- Description: Abstract: Coal contributes to 40% of the world’s energy production and the process of energy production from coal contributes to 40% of the world’s carbon dioxide emissions which have led to global warming and climate change. Thermochemical processes like pyrolysis, gasification and carbonification are used to utilize coal and this coal can be mixed with other sources of energy such as biomass for environmental protection, a higher energy densification and char yield. In this study Morupule coal was co-pyrolyzed with cow dung in a fixed bed reactor with the aim of producing char whilst reducing the net carbon dioxide emissions. Co-pyrolysis of coal with biomass yields char, gas and liquid fuel. Char is used in various sectors such as agriculture to improve soil quality hence increasing crop yields and as an adsorbent for wastewater treatment. The co-pyrolysis process was performed at 500oC and atmospheric pressure under an inert atmosphere which contained argon. Pyrolysis using a fixed bed reactor was performed on coal and cow dung at blend ratios of coal to cow dung of 0:100, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0. Proximate analysis results indicated that char had a higher fixed carbon compared to those from the individual substrates. Calorific value (CV) tests of the chars indicated that reducing to 90:10 ratio the cow dung concentration resulted in CV increases. This study shows that there is a synergic effect between the sub-bituminous Morupule coal and cow dung.
- Full Text:
- Authors: Motlhatlhedi, T. J. , Muzenda, E. , Mamvura, T. A.
- Date: 2020
- Subjects: Cow dung , Char , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/461807 , uj:41146 , Citation: Motlhatlhedi, T.J., Muzenda, E. & Mamvura, T.A. 2020. Char production through the co-pyrolysis of coal and biomass in a fixed FED reactor.
- Description: Abstract: Coal contributes to 40% of the world’s energy production and the process of energy production from coal contributes to 40% of the world’s carbon dioxide emissions which have led to global warming and climate change. Thermochemical processes like pyrolysis, gasification and carbonification are used to utilize coal and this coal can be mixed with other sources of energy such as biomass for environmental protection, a higher energy densification and char yield. In this study Morupule coal was co-pyrolyzed with cow dung in a fixed bed reactor with the aim of producing char whilst reducing the net carbon dioxide emissions. Co-pyrolysis of coal with biomass yields char, gas and liquid fuel. Char is used in various sectors such as agriculture to improve soil quality hence increasing crop yields and as an adsorbent for wastewater treatment. The co-pyrolysis process was performed at 500oC and atmospheric pressure under an inert atmosphere which contained argon. Pyrolysis using a fixed bed reactor was performed on coal and cow dung at blend ratios of coal to cow dung of 0:100, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0. Proximate analysis results indicated that char had a higher fixed carbon compared to those from the individual substrates. Calorific value (CV) tests of the chars indicated that reducing to 90:10 ratio the cow dung concentration resulted in CV increases. This study shows that there is a synergic effect between the sub-bituminous Morupule coal and cow dung.
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Analysis of clean coal technology in Nigeria for energy generation
- Oboirien, B. O., North, B. C., Obayopo, S. O., Odusote, J. K., Sadiku, E. R.
- Authors: Oboirien, B. O. , North, B. C. , Obayopo, S. O. , Odusote, J. K. , Sadiku, E. R.
- Date: 2018
- Subjects: Clean Coal Technologies , Nigeria , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/283092 , uj:30517 , Citation: Oboirien, B.O. et al. 2018. Analysis of clean coal technology in Nigeria for energy generation.
- Description: Abstract: An analysis of clean coal technologies for the recovery of energy from Nigerian coals was carried out. The coal mines studied are Onyeama, Ogwashi, Ezimo, Inyi, Amasiodo, Okaba, Lafia-Obi, Owukpa Owukpa, Ogboyoga and Okpara. The estimated reserves of the ten coal deposit amount to 2.1 Gt, which is about 84 % of the total coal reserves of the country 2.5 Gt of coal Nigeria. The key clean coal technologies studied are Ultra-Supercritical Combustion (USC), Supercritical-Fluidised Bed Combustion (FBC), Integrated Gasification Combined Cycle (IGCC) and Coal bed Methane (CBM) and the results were compared with conventional subcritical pulverised fuel combustion (PF). The total potential energy recovery from these technologies are: PF 5800 TWh, FBC 7250 TWh, IGCC 7618 TWh, and USC 8519 TWh. This indicates an increase of about 31% in the total electricity generation if USC technology is used instead of the conventional sub-critical PF technology...
- Full Text:
- Authors: Oboirien, B. O. , North, B. C. , Obayopo, S. O. , Odusote, J. K. , Sadiku, E. R.
- Date: 2018
- Subjects: Clean Coal Technologies , Nigeria , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/283092 , uj:30517 , Citation: Oboirien, B.O. et al. 2018. Analysis of clean coal technology in Nigeria for energy generation.
- Description: Abstract: An analysis of clean coal technologies for the recovery of energy from Nigerian coals was carried out. The coal mines studied are Onyeama, Ogwashi, Ezimo, Inyi, Amasiodo, Okaba, Lafia-Obi, Owukpa Owukpa, Ogboyoga and Okpara. The estimated reserves of the ten coal deposit amount to 2.1 Gt, which is about 84 % of the total coal reserves of the country 2.5 Gt of coal Nigeria. The key clean coal technologies studied are Ultra-Supercritical Combustion (USC), Supercritical-Fluidised Bed Combustion (FBC), Integrated Gasification Combined Cycle (IGCC) and Coal bed Methane (CBM) and the results were compared with conventional subcritical pulverised fuel combustion (PF). The total potential energy recovery from these technologies are: PF 5800 TWh, FBC 7250 TWh, IGCC 7618 TWh, and USC 8519 TWh. This indicates an increase of about 31% in the total electricity generation if USC technology is used instead of the conventional sub-critical PF technology...
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Prediction of emissions and profits from a biomass, tyre, and coal fired co-gasification CHP plant using artificial neural network: Nigerian and South African perspectives
- Ozonoh, M, Aniokete, T C, Oboirien, B O, Udeh, B C, Yoro, K O, Daramola, M O
- Authors: Ozonoh, M , Aniokete, T C , Oboirien, B O , Udeh, B C , Yoro, K O , Daramola, M O
- Date: 2019
- Subjects: Artificial Neural Networks , Biomass , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/406563 , uj:34187 , Citation: Ozonoh, M. et al. 2019 : Prediction of emissions and profits from a biomass, tyre, and coal fired co-gasification CHP plant using artificial neural network: Nigerian and South African perspectives. DOI: 10.1088/1742-6596/1378/2/022021.
- Description: Abstract : The local sourcing of feedstock for energy generation will reduce costs in the power plant, and promote energy sustainability. Most times, potential investors in this area show interest about understanding the profitability of the business because, the information boosts the confidence of the investors in the project, and gives them the opportunity of making a short and long term plans about the business. The emissions arising from the energy plant is an important aspect of the venture that requires proper attention, otherwise the costs of emission control may consume a greater part of the profit, hence rendering the business un-viable. Nigeria and South Africa (SA) have abundant biomass (e.g. corn cob, sugarcane bagasse, & pine saw dust) coal and tyre that can be used as fuel in an energy plant. A 10 MW CHP plant was fired with coal and biomass, and tyre obtained from Nigeria and South Africa (SA) respectively, at ratios of 1:1, 3:2, and 4:1 to study the emissions and profits in the plant. An empirical model was employed to estimate the annual amount of feedstock and feed rate required for the plant, after which, an artificial neural network (ANN); LevenbergMarquardt algorithm was used to predict the emissions and profits in the plant for 20-year- investment period with feedstock costing (WFC) and without feedstock costing (WOFC). The profit obtained from the South African feedstock, WFC and WOFC; produced about 45.18 % and 36.83 % ($3,900,000.07 and $3,179,184.49) higher profits than the Nigerian feedstock, but the CO, NOX, & SO2 emissions from Nigerian feedstock were lower than that of SA. The findings from this study could be used as a platform for decision making by potential investors and stake-holders, and further research and development in the area.
- Full Text:
- Authors: Ozonoh, M , Aniokete, T C , Oboirien, B O , Udeh, B C , Yoro, K O , Daramola, M O
- Date: 2019
- Subjects: Artificial Neural Networks , Biomass , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/406563 , uj:34187 , Citation: Ozonoh, M. et al. 2019 : Prediction of emissions and profits from a biomass, tyre, and coal fired co-gasification CHP plant using artificial neural network: Nigerian and South African perspectives. DOI: 10.1088/1742-6596/1378/2/022021.
- Description: Abstract : The local sourcing of feedstock for energy generation will reduce costs in the power plant, and promote energy sustainability. Most times, potential investors in this area show interest about understanding the profitability of the business because, the information boosts the confidence of the investors in the project, and gives them the opportunity of making a short and long term plans about the business. The emissions arising from the energy plant is an important aspect of the venture that requires proper attention, otherwise the costs of emission control may consume a greater part of the profit, hence rendering the business un-viable. Nigeria and South Africa (SA) have abundant biomass (e.g. corn cob, sugarcane bagasse, & pine saw dust) coal and tyre that can be used as fuel in an energy plant. A 10 MW CHP plant was fired with coal and biomass, and tyre obtained from Nigeria and South Africa (SA) respectively, at ratios of 1:1, 3:2, and 4:1 to study the emissions and profits in the plant. An empirical model was employed to estimate the annual amount of feedstock and feed rate required for the plant, after which, an artificial neural network (ANN); LevenbergMarquardt algorithm was used to predict the emissions and profits in the plant for 20-year- investment period with feedstock costing (WFC) and without feedstock costing (WOFC). The profit obtained from the South African feedstock, WFC and WOFC; produced about 45.18 % and 36.83 % ($3,900,000.07 and $3,179,184.49) higher profits than the Nigerian feedstock, but the CO, NOX, & SO2 emissions from Nigerian feedstock were lower than that of SA. The findings from this study could be used as a platform for decision making by potential investors and stake-holders, and further research and development in the area.
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Techno-economic analysis of electricity and heat production by co-gasification of coal, biomass and waste tyre in South Africa
- Ozonoh, M., Aniokete, T. C., Oboirien, B. O., Daramola, M. O.
- Authors: Ozonoh, M. , Aniokete, T. C. , Oboirien, B. O. , Daramola, M. O.
- Date: 2018
- Subjects: Co-gasification , Biomass waste , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/282999 , uj:30506 , Citation: Ozonoh, M. et al. 2018. Techno-economic analysis of electricity and heat production by co-gasification of coal, biomass and waste tyre in South Africa.
- Description: Abstract: South Africa has large deposit of coal that supports about 95 % of electric power generation in the country. The fuel is fast depleting, though the current reserve may serve for the next century. However, the emissions from the coal projects huge threat to the environment. Similarly, the country has abundant solid wastes that can be co-gasified with coal to H2 enriched syngas for clean energy production. A 5 MW combined heat and power plant was studied using different coal-to-solid waste ratios including 1:1, 3:2, and 4:1 with feedstocks costing, and without feedstock costing. The lower heating value of the fuels, determined from a model equation was applied to estimate the annual feedstocks requirement and the feed rate...
- Full Text:
- Authors: Ozonoh, M. , Aniokete, T. C. , Oboirien, B. O. , Daramola, M. O.
- Date: 2018
- Subjects: Co-gasification , Biomass waste , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/282999 , uj:30506 , Citation: Ozonoh, M. et al. 2018. Techno-economic analysis of electricity and heat production by co-gasification of coal, biomass and waste tyre in South Africa.
- Description: Abstract: South Africa has large deposit of coal that supports about 95 % of electric power generation in the country. The fuel is fast depleting, though the current reserve may serve for the next century. However, the emissions from the coal projects huge threat to the environment. Similarly, the country has abundant solid wastes that can be co-gasified with coal to H2 enriched syngas for clean energy production. A 5 MW combined heat and power plant was studied using different coal-to-solid waste ratios including 1:1, 3:2, and 4:1 with feedstocks costing, and without feedstock costing. The lower heating value of the fuels, determined from a model equation was applied to estimate the annual feedstocks requirement and the feed rate...
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Geological controls on no. 4 seam roof conditions at New Denmark Colliery, Highveld Coal Field, Karoo Basin, South Africa
- Authors: Stanimirovic, Jasmina
- Date: 2009-01-28T09:43:30Z
- Subjects: Facies (Geology) , Coal , Stratigraphic geology , Sedimentology , Mine roof control , Karoo Supergroup , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:14849 , http://hdl.handle.net/10210/1971
- Description: M.Sc. , The coal-bearing Permian Vryheid Formation of the Ecca Group (Karoo Supergroup) was investigated at New Denmark Colliery, situated in the north east section of the Karoo Basin, South Africa. The lithostratigraphy of the sequence is defined in terms of conventional lithostratigraphic terminology but also by applying detailed genetic stratigraphic schemes that have previously been proposed for the adjacent coalfields. The succession is divided up into depositional sequences named after the underlying and overlying coal seams, the No. 2, 3, 4 and 5 seam sequences. The sedimentary succession was divided up into five facies, namely: conglomerate facies, sandstone facies, interlaminated sandstone-siltstone facies, siltstone facies and coal facies. These were interpreted hydrodynamically. Facies assemblages were then interpreted palaeoenvironmentally. Glacial, fluvial, deltaic and transgressive marine sequences were responsible for forming this sedimentary succession. Attention was then focussed on the main economic No. 4 seam, which is mined underground at the colliery. Detailed subsurface geological cross-sections, core sequences and isopach maps of the No. 4 seam coal and the lithologies above, were used to determine specific aspects of the depositional environment that could contribute to unstable roof conditions above No. 4 seam. Coarsening-upward deltaic cycles, fining-upward bedload fluvial cycles, glauconite sandstone marine transgressions and crevasse-splay deposits are recognized in the overlying strata. Poor roof conditions occur parallel to palaeochannel margins because the interbedded channel sandstone and adjacent flood plain argillites cause collapsing along bedding plane surfaces. Rider coals overlying thin crevasse-splay sequences in close proximity to the No. 4 seam, create one of the most serious roof conditions; complete collapse occurs along the rider coal contact with the underlying splay deposits. Differential compaction of mudrock/shale/siltstone over more competent sandstone causes slickensided surfaces that weaken the roof lithologies. Correct identification of these sedimentological features will enable the prediction of potential poor roof conditions during mining operations and mine planning.
- Full Text:
- Authors: Stanimirovic, Jasmina
- Date: 2009-01-28T09:43:30Z
- Subjects: Facies (Geology) , Coal , Stratigraphic geology , Sedimentology , Mine roof control , Karoo Supergroup , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:14849 , http://hdl.handle.net/10210/1971
- Description: M.Sc. , The coal-bearing Permian Vryheid Formation of the Ecca Group (Karoo Supergroup) was investigated at New Denmark Colliery, situated in the north east section of the Karoo Basin, South Africa. The lithostratigraphy of the sequence is defined in terms of conventional lithostratigraphic terminology but also by applying detailed genetic stratigraphic schemes that have previously been proposed for the adjacent coalfields. The succession is divided up into depositional sequences named after the underlying and overlying coal seams, the No. 2, 3, 4 and 5 seam sequences. The sedimentary succession was divided up into five facies, namely: conglomerate facies, sandstone facies, interlaminated sandstone-siltstone facies, siltstone facies and coal facies. These were interpreted hydrodynamically. Facies assemblages were then interpreted palaeoenvironmentally. Glacial, fluvial, deltaic and transgressive marine sequences were responsible for forming this sedimentary succession. Attention was then focussed on the main economic No. 4 seam, which is mined underground at the colliery. Detailed subsurface geological cross-sections, core sequences and isopach maps of the No. 4 seam coal and the lithologies above, were used to determine specific aspects of the depositional environment that could contribute to unstable roof conditions above No. 4 seam. Coarsening-upward deltaic cycles, fining-upward bedload fluvial cycles, glauconite sandstone marine transgressions and crevasse-splay deposits are recognized in the overlying strata. Poor roof conditions occur parallel to palaeochannel margins because the interbedded channel sandstone and adjacent flood plain argillites cause collapsing along bedding plane surfaces. Rider coals overlying thin crevasse-splay sequences in close proximity to the No. 4 seam, create one of the most serious roof conditions; complete collapse occurs along the rider coal contact with the underlying splay deposits. Differential compaction of mudrock/shale/siltstone over more competent sandstone causes slickensided surfaces that weaken the roof lithologies. Correct identification of these sedimentological features will enable the prediction of potential poor roof conditions during mining operations and mine planning.
- Full Text:
Upgrade of coal using dry X-Ray transmission sorting
- Authors: Tshambo, Neo
- Date: 2018
- Subjects: Coal , Coal - Analysis
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280236 , uj:30109
- Description: M.Ing. (Engineering Management) , Abstract: Run-off-Mine (ROM) coal processing will become more difficult in the future as the quality of raw coal mined continues to decline in the Witbank coalfields. The extensive reserves of coal that remain in the Waterberg and Soutpansberg coalfields are of relatively low quality compared to that from the Witbank area. Coal processing plants will have to deal with lower yields and employ robust processes that can cope with high mounts of waste rejection. The effective use of water in coal processing plants will also become more important as water availability is expected to decrease significantly in the future. Dry sorting techniques such as x-ray transmission (XRT) have been successfully implemented for de-stoning/waste rejection applications both locally and abroad in mining applications. Mintek investigated the possibility of using XRT to produce both low-grade Eskomspecification product and high–grade, niche quality product for the metallurgical sector. Preliminary laboratory XRT test work results on coal from Vlakfontein mine (4 Upper and 4 Lower seams) indicated that different grades of coal could be distinguished by XRT sensors as the basis of an upgrading process. However, in order to evaluate sorter separation efficiency at industrial throughput rates, a production scale XRT sorting plant was commissioned at Vlakfontein mine with a design capacity of 125 tons/hr of sorter feed. The 4 Upper seam was not able to achieve high quality coal with calorific values (CVs) in excess of 25 MJ/kg. This was evident from the feed washability analysis, as the seam is inherently of a low quality with only 30% of the feed mass having CVs in excess of 25 MJ/kg. However, this material could be upgraded to a saleable Eskom grade product by XRT. The 4 Lower seam was more encouraging, the feed washability analysis indicates that 67.5% of the feed mass has CVs in excess of 25 MJ/kg. The 4 Lower high grade products, are suitable for Richards bay terminal 3 (RB3) export grade coal. The CV values obtained after XRT sorting are on-specification for export and the metallurgical markets. XRT Sorting was able to separate coal from waste and in addition upgrade a low grade coal to a saleable grade of thermal coal. The process has lower operating and capital expenditure compared to conventional coal processing methods, however at lower efficiencies. The Ecart-probable (Ep) of the sorters ranges between 0.1-0.20 which is high in comparison to the 0.02-0.03 typically expected for dense medium circuits. It is thus necessary to balance separation efficiency which leads to lower product yields against the lower capital and operating cost of the dry XRT sorting facilities. The study has demonstrated that the addition of sensor-based particle ore sorting to the mineral processing value chain can have significant influence on the overall economic and environmental aspects of the minerals processing plant.
- Full Text:
- Authors: Tshambo, Neo
- Date: 2018
- Subjects: Coal , Coal - Analysis
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280236 , uj:30109
- Description: M.Ing. (Engineering Management) , Abstract: Run-off-Mine (ROM) coal processing will become more difficult in the future as the quality of raw coal mined continues to decline in the Witbank coalfields. The extensive reserves of coal that remain in the Waterberg and Soutpansberg coalfields are of relatively low quality compared to that from the Witbank area. Coal processing plants will have to deal with lower yields and employ robust processes that can cope with high mounts of waste rejection. The effective use of water in coal processing plants will also become more important as water availability is expected to decrease significantly in the future. Dry sorting techniques such as x-ray transmission (XRT) have been successfully implemented for de-stoning/waste rejection applications both locally and abroad in mining applications. Mintek investigated the possibility of using XRT to produce both low-grade Eskomspecification product and high–grade, niche quality product for the metallurgical sector. Preliminary laboratory XRT test work results on coal from Vlakfontein mine (4 Upper and 4 Lower seams) indicated that different grades of coal could be distinguished by XRT sensors as the basis of an upgrading process. However, in order to evaluate sorter separation efficiency at industrial throughput rates, a production scale XRT sorting plant was commissioned at Vlakfontein mine with a design capacity of 125 tons/hr of sorter feed. The 4 Upper seam was not able to achieve high quality coal with calorific values (CVs) in excess of 25 MJ/kg. This was evident from the feed washability analysis, as the seam is inherently of a low quality with only 30% of the feed mass having CVs in excess of 25 MJ/kg. However, this material could be upgraded to a saleable Eskom grade product by XRT. The 4 Lower seam was more encouraging, the feed washability analysis indicates that 67.5% of the feed mass has CVs in excess of 25 MJ/kg. The 4 Lower high grade products, are suitable for Richards bay terminal 3 (RB3) export grade coal. The CV values obtained after XRT sorting are on-specification for export and the metallurgical markets. XRT Sorting was able to separate coal from waste and in addition upgrade a low grade coal to a saleable grade of thermal coal. The process has lower operating and capital expenditure compared to conventional coal processing methods, however at lower efficiencies. The Ecart-probable (Ep) of the sorters ranges between 0.1-0.20 which is high in comparison to the 0.02-0.03 typically expected for dense medium circuits. It is thus necessary to balance separation efficiency which leads to lower product yields against the lower capital and operating cost of the dry XRT sorting facilities. The study has demonstrated that the addition of sensor-based particle ore sorting to the mineral processing value chain can have significant influence on the overall economic and environmental aspects of the minerals processing plant.
- Full Text:
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