Flue gas desulphurisation (FGD) is a crucial method to minimise the SO2 emissions from industrial processes. The FGD system utilise an alkaline sorbent to remove SO2 from the flue gases. Calcium in form of limestone is a commonly used sorbent where gypsum is produced asa by-product. However, the limestone reactivity, along with impurities within the sorbent, can significantly influence the effectiveness of SO2 removal and the quality of the by-products. At Heidelberg materials Cement Sverige an intermediate product, raw meal (RM) 8, is used assorbent in the FGD and gypsum is used as setting retarder in the cement. The aim with this project is to examine if raw meal 7 or A-sten is a better sorbent than raw meal 8 with respect to consumption rate, gypsum quality and its effect on the cement properties, and economic viability. To accomplish this a theoretical study was performed along with data analysis. RM 7 and A-sten are both purer than RM 8 but the raw material cost for RM 7 is about 1.24 times the raw material cost for RM 8 and the production costs and transportation costs are greater for RM 7 than for RM 8. The raw material cost for A-sten is about 0.45 times the cost for RM 8 but is not produced on site. All sorbents contain magnesium which can react with sulphur and precipitate as epsomite or hexahydrite, which also acts as retarders, where epsomite retard the cement setting time significantly compared to gypsum. To calculate the consumption rate of raw meal and A-sten into the scrubber three different methods were used. The difference between the methods lies in the consideration of how the calcium and magnesium species in the sorbent react with sulphur, with all calcium and magnesium reacting with sulphur in method 1, method 2 take the mass fraction of sulphurcontaining species into consideration, and method 3 incorporating mole fractions of calcium and magnesium species as well as sulphur from the sorbent. The pH and SO2 emissions were analysed for two different time periods where the first analysed period shows a correlation between low pH and high SO2 emissions, while the latter analysed period lacks a clear pH-SO2 correlation. A correlation between a lower pH and a lower percentage of MgSO4⸱6H2O and MgSO4⸱7H2O in the slurry could be made. The calculated rawmeal flow rate for RM 8 is between 520 and 554 kg/h, depending on the method used. To achieve the same desulphurisation efficiency with RM 7 the flow was calculated to 499-538kg/h and 427-464 kg/h for A-sten. Given the comparable mass flow rates of RM 8 and RM 7 it is advisable to retain RM 8 as asorbent in the scrubber regardless of the higher magnesium content due the higher cost associated with RM 7. However, the epsomite content in the slurry should be considered when optimising sulphur in cement production. Using A-sten as sorbent would minimise the rawmaterial costs and result in purer gypsum slurry with a lower epsomite content. Operating with a purer sorbent can also enhance the efficiency of the FGD process, leading to lower SO2 emissions. The calculations in the report assume that calcium and magnesium in the different sorbents react similarly, further analysis of their reactivity is recommended for more accurate results. / Rökgasavsvavling är en avgörande metod för att minimera SO2-utsläppen från industriella processer. Rökgasavsvaling använder en alkalisk sorbent för att avlägsna SO2 från rökgaserna. Kalcium i form av kalksten är en vanligt förekommande sorbent där gips produceras som en biprodukt. Kalkstensreaktiviteten, tillsammans med föroreningar i sorbenten kan emellertid avsevärt påverka avsvavlingseffektiviteten och biproduktens kvalitet. På Heidelberg materials Cement Sverige används en mellanprodukt, råmjöl (RM) 8, somsorbent i avsvavlingsprocessen och gipset används som härdningshämmare i cementet. Syftet med detta projekt är att undersöka om råmjöl 7 eller A-sten är en bättre sorbent än råmjöl 8 med avseende på konsumtionshastighet, gipskvalitet och dess effekt på cementens egenskapersamt ekonomisk bärkraft. För att uppnå syftet genomfördes en teoretisk studie tillsammans med dataanalys. RM 7 och A-sten är båda renare än RM 8 men råvarukostnaden för RM 7 är cirka 1,24 gånger råvarukostnaden för RM8. Dessutom är produktions- och transportkostnaderna högre för RM7 än för RM 8. Råvarukostnaden för A-sten är cirka 0,45 gånger råvarukostnaden för RM 8, dock mals inte A-sten på plats. Alla sorbenter innehåller magnesium som kan reagera med svavel och fälla ut som epsomit eller hexahydrit, vilka också har en härdningshämmande effekt, där epsomit fördröjer cementens härdning signifikant jämfört med gips. För att beräkna konsumtionshastigheten för råmjöl och A-sten i skrubbern användes tre olika metoder. Skillnaden mellan metoderna är hur kalcium- och magnesiumarterna i sorbenten reagerar med svavel, där allt kalcium och magnesium reagerar med svavel i metod 1. Metod 2 tar hänsyn till massfraktionen av svavelhaltiga ämnen och metod 3 innehåller molfraktioner av kalcium- och magnesiumarter samt svavel från sorbenten. pH och SO2-utsläppen analyserades under två olika tidsperioder där den första perioden visar ett samband mellan lågt pH och höga SO2-utsläpp, medan den senare analyserade perioden saknar ett tydligt pH-SO2-samband. En korrelation mellan ett lägre pH och en lägre andel MgSO4⸱6H2O och MgSO4⸱7H2O i gipsslurryn skulle kunna göras. Det beräknade flödet av råmjöl för RM 8 är mellan 520 och 554 kg/h, beroende på vilken metod som används. För att uppnå samma avsvavlingseffektivitet med RM 7 måste flödet vara 499–538 kg/h och 427–464 kg/h för A-sten. Med tanke på de jämförbara massflödena för RM 8 och RM 7 är det lämpligt att behålla RM 8 som sorbent i skrubbern, trots den högre magnesiumhalten, på grund av de högre kostnaderna för RM 7. Epsomithalten i slurryn bör dock tas i beakting vid optimering av svavel i cementproduktionen. Att använda A-sten som sorbent skulle minimera råvarukostnaderna och resultera i en renare gipsslurry med lägre epsomithalt. Att använda med en renare sorbent kan också förbättra avsvavlingseffektiviteten, vilket leder till lägre SO2-utsläpp. Beräkningarna i rapporten förutsätter att kalcium och magnesium i de olika sorbenterna reagerar lika, ytterligare analys av deras reaktivitet rekommenderas för mer exakta resultat.

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

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

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

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

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

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

This master thesis deals with the feasibility studies desulphurization of powder granulation K3 boiler at Olomouc heating station. K3 boiler burns black energetic coal and after January 1st, 2016 will not meet new more strict emission limits. The theoretical part of the thesis charts usable desulphurization methods from which the semi-dry NID appears as the most appropriate one. In the practical part there is performed a stoichiometric calculation of the flue gas and the balance of raw materials and output products. The possibility of NID method usage is confirmed here. Next the annual operating cost of the desulfurization process is calculated and some NID systems already installed references are presented.