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The Solid Oxide Fuel Cell (SOFC) is a promising technology for electricity generation. It converts the chemical energy of the fuel gas directly to electricity energy and therefore, very high electrical efficiencies can be achieved. The high operating temperature of the SOFC also provides excellent possibilities for cogeneration applications. In addition to producing power very efficiently, the SOFC has the potential to concentrate CO₂ with a minimum of an overall efficiency loss. Concentration of CO₂ is a desirable feature of a power generation process so that the CO₂ may be subsequently sequestered thus preventing its contribution to global warming. The primary purpose of this research project was to investigate the role of the SOFC technology in power generation processes and explore its potential for CO₂ capture in power plants. <br /><br /> This thesis introduces an AspenPlus^TM SOFC stack model based on the natural gas feed tubular internal reforming SOFC technology. It was developed utilizing existing AspenPlus^TM functions and unit operation models. This SOFC model is able to provide detailed thermodynamic and parametric analysis of the SOFC operation and can easily be extended to study the entire process consisting of the SOFC stack and balance of plant. <br /><br /> Various SOFC-based power generation cycles were studied in this thesis. Various options for concentrating CO₂ in these power generation systems were also investigated and discussed in detail. All the processes simulations were implemented in AspenPlus^TM extending from the developed natural gas feed tubular SOFC stack model. The study shows that the SOFC technology has a promising future not only in generating electricity in high efficiency but also in facilitating CO₂ concentration, but the cost of the proposed processes still need be reduced so SOFCs can become a technical as well as economic feasible solution for power generation.

A solid oxide fuel cell (SOFC) is an energy conversion device that has the potential to efficiently generate electricity in an environmentally-friendly manner. In general, a SOFC operates between 750&deg;C and 1000&deg;C utilizing hydrogen or hydrocarbons as fuel and air as an oxidant. The three major components comprising a fuel cell are the electrolyte, the cathode, and the anode. At present, the state-of-the-art SOFC is made from a dense yttria-stabilized zirconia (YSZ) electrolyte, a porous lanthanum manganite cathode, and a porous nickel/YSZ composite anode. With the advent of the anode-supported SOFC and the increased interest in using a wider range of fuels, such as those containing sulphur, knowledge of the anode properties is becoming more important. <br /> The properties of the current anodes are limited due to the narrow range of nickel loadings imposed by the minimum nickel content for electrical conductivity and the maximum allowable nickel loading to avoid thermal mismatch with the YSZ electrolyte. In addition, there is little research presented in the literature regarding the use of nickel metal as a starting anode material, rather than the traditional nickel oxide powder, and how porosity may affect the anode properties. <br /> The purpose of this investigation is to determine the influence nickel morphology and porosity distribution have on the processing and properties of tape cast Ni/YSZ composites. Specifically, the sintering characteristics, electrical conductivity, and thermal expansion behaviour of tape cast composites created from YSZ, nickel, nickel oxide (NiO), nickel coated graphite (NiGr), and/or graphite (Gr) powders are investigated. In addition to samples made from 100% YSZ, 100% Ni, and 100% NiO powders, five composite types were created for this investigation: NiO/YSZ, NiO&Gr/YSZ, Ni/YSZ, NiGr/YSZ, and Ni&Gr/YSZ each with nickel loadings varying between 4 vol% Ni of total solids and 77 vol% Ni of total solids. Another set of composites with a fixed nickel loading of 27 vol% Ni and 47 vol% Ni of total solids and varying graphite loadings were also created. <br /> During the burnout stage, the composites made from nickel oxide powder shrink slightly while the composites made from nickel metal expand due to nickel oxidation. Graphite additions below 20 vol% of the green volume do not alter the dimensional changes of the composites during burnout, but graphite loadings greater than 25 vol% of the green volume cause significant expansion in the thickness of the composites. <br /> After sintering, the amount of volumetric sintering shrinkage decreases with higher nickel loadings and is greater for the composites made with nickel oxide compared to the composites made from nickel metal. The porosity generated in the composites containing graphite is slightly higher than the volume of graphite added to the composite and is much greater than the porosity contained in the graphite-free composites. <br /> Dimensional changes of the porous Ni/YSZ and NiO/YSZ composites during both burnout and sintering were analysed based on concepts of constrained sintering of composite powder mixtures. In some cases constrained sintering was evident, while in others, a more simple rule of mixtures behaviour for shrinkage as a function of YSZ content was observed. <br /> When nickel oxide is reduced to nickel metal during the reduction stage there is essentially no change in the composite volume for the composites containing YSZ because the YSZ prevents the composites from shrinking. After reduction the additional porosity generated in the composites is equivalent to the change in volume due to the reduction of nickel oxide to nickel metal. <br /> When measuring the electrical conductivity, each composite type demonstrated classic percolation behaviour. The NiGr/YSZ composites had the lowest percolation threshold, followed by the Ni/YSZ and NiO/YSZ composites. When graphite was added with a nickel coating, the added porosity did not disrupt the nickel percolation network and allowed the nickel to occupy a larger effective volume compared to a composite made with similar sized solid nickel particles. When graphite was added to the composites, the electrical conductivity was reduced and the percolation threshold increased. <br /> Generally, the coefficient of thermal expansion (CTE) for Ni/YSZ composites are expected to follow the rule of mixtures prediction since the elastic properties for nickel and YSZ are similar. However when porosity is distributed unevenly between the YSZ and nickel phases, the CTE prediction will deviate from the rule of mixtures. When cornstarch was added to the NiGr/YSZ composites, the CTE increased as the amount of porosity in the YSZ phase increased. The CTE of the NiGr/YSZ composites followed the rule of mixtures indicating that the porosity was evenly distributed between the nickel and YSZ phases. For the other composite types, the measured CTE was higher than the rule of mixtures prediction suggesting that more porosity was contained within the YSZ phase.

There has always been a desire to develop industrial processes that minimize the resources they use, and the wastes they generate. The problem is when new guidelines are forced upon long established processes, such as solvent based coating operations. This means instead of integrating an emission reduction technology into the original design of the process, it is added on after the fact. This significantly increases the costs associated with treating emissions. In this work the ultimate goal is the design of an “add-on” abatement system to treat emissions from solvent based coating processes with high destruction efficiency, and lower costs than systems in current use. Since emissions from processes that utilize solvent based coatings are primarily comprised of volatile organic compounds (VOCs), the treatment of these compounds will be the focus. VOCs themselves contain a significant amount of energy. If these compounds could be destroyed by simultaneously extracting the energy they release, operational costs could be substantially reduced. This thesis examines the use of model-based design to develop and optimize a VOC abatement technology that uses a Solid Oxide Fuel Cell (SOFC) for energy recovery. The model was built using existing HYSYS unit operation models, and was able to provide a detailed thermodynamic and parametric analysis of this technology. The model was validated by comparison to published literature results and through the use of several Design of Experiment factorial analyses. The model itself illustrated that this type of system could achieve 95% destruction efficiency with performance that was superior to that of Thermal Oxidation, Biological Oxidation, or Adsorption VOC abatement technologies. This was based upon design criteria that included ten year lifecycle costs and operational flexibility, as well as the constraint of meeting (or exceeding) current regulatory thresholds.

The Solid Oxide Fuel Cell (SOFC) is a promising technology for electricity generation. It converts the chemical energy of the fuel gas directly to electricity energy and therefore, very high electrical efficiencies can be achieved. The high operating temperature of the SOFC also provides excellent possibilities for cogeneration applications. In addition to producing power very efficiently, the SOFC has the potential to concentrate CO₂ with a minimum of an overall efficiency loss. Concentration of CO₂ is a desirable feature of a power generation process so that the CO₂ may be subsequently sequestered thus preventing its contribution to global warming. The primary purpose of this research project was to investigate the role of the SOFC technology in power generation processes and explore its potential for CO₂ capture in power plants. <br /><br /> This thesis introduces an AspenPlus^TM SOFC stack model based on the natural gas feed tubular internal reforming SOFC technology. It was developed utilizing existing AspenPlus^TM functions and unit operation models. This SOFC model is able to provide detailed thermodynamic and parametric analysis of the SOFC operation and can easily be extended to study the entire process consisting of the SOFC stack and balance of plant. <br /><br /> Various SOFC-based power generation cycles were studied in this thesis. Various options for concentrating CO₂ in these power generation systems were also investigated and discussed in detail. All the processes simulations were implemented in AspenPlus^TM extending from the developed natural gas feed tubular SOFC stack model. The study shows that the SOFC technology has a promising future not only in generating electricity in high efficiency but also in facilitating CO₂ concentration, but the cost of the proposed processes still need be reduced so SOFCs can become a technical as well as economic feasible solution for power generation.

A solid oxide fuel cell (SOFC) is an energy conversion device that has the potential to efficiently generate electricity in an environmentally-friendly manner. In general, a SOFC operates between 750&deg;C and 1000&deg;C utilizing hydrogen or hydrocarbons as fuel and air as an oxidant. The three major components comprising a fuel cell are the electrolyte, the cathode, and the anode. At present, the state-of-the-art SOFC is made from a dense yttria-stabilized zirconia (YSZ) electrolyte, a porous lanthanum manganite cathode, and a porous nickel/YSZ composite anode. With the advent of the anode-supported SOFC and the increased interest in using a wider range of fuels, such as those containing sulphur, knowledge of the anode properties is becoming more important. <br /> The properties of the current anodes are limited due to the narrow range of nickel loadings imposed by the minimum nickel content for electrical conductivity and the maximum allowable nickel loading to avoid thermal mismatch with the YSZ electrolyte. In addition, there is little research presented in the literature regarding the use of nickel metal as a starting anode material, rather than the traditional nickel oxide powder, and how porosity may affect the anode properties. <br /> The purpose of this investigation is to determine the influence nickel morphology and porosity distribution have on the processing and properties of tape cast Ni/YSZ composites. Specifically, the sintering characteristics, electrical conductivity, and thermal expansion behaviour of tape cast composites created from YSZ, nickel, nickel oxide (NiO), nickel coated graphite (NiGr), and/or graphite (Gr) powders are investigated. In addition to samples made from 100% YSZ, 100% Ni, and 100% NiO powders, five composite types were created for this investigation: NiO/YSZ, NiO&Gr/YSZ, Ni/YSZ, NiGr/YSZ, and Ni&Gr/YSZ each with nickel loadings varying between 4 vol% Ni of total solids and 77 vol% Ni of total solids. Another set of composites with a fixed nickel loading of 27 vol% Ni and 47 vol% Ni of total solids and varying graphite loadings were also created. <br /> During the burnout stage, the composites made from nickel oxide powder shrink slightly while the composites made from nickel metal expand due to nickel oxidation. Graphite additions below 20 vol% of the green volume do not alter the dimensional changes of the composites during burnout, but graphite loadings greater than 25 vol% of the green volume cause significant expansion in the thickness of the composites. <br /> After sintering, the amount of volumetric sintering shrinkage decreases with higher nickel loadings and is greater for the composites made with nickel oxide compared to the composites made from nickel metal. The porosity generated in the composites containing graphite is slightly higher than the volume of graphite added to the composite and is much greater than the porosity contained in the graphite-free composites. <br /> Dimensional changes of the porous Ni/YSZ and NiO/YSZ composites during both burnout and sintering were analysed based on concepts of constrained sintering of composite powder mixtures. In some cases constrained sintering was evident, while in others, a more simple rule of mixtures behaviour for shrinkage as a function of YSZ content was observed. <br /> When nickel oxide is reduced to nickel metal during the reduction stage there is essentially no change in the composite volume for the composites containing YSZ because the YSZ prevents the composites from shrinking. After reduction the additional porosity generated in the composites is equivalent to the change in volume due to the reduction of nickel oxide to nickel metal. <br /> When measuring the electrical conductivity, each composite type demonstrated classic percolation behaviour. The NiGr/YSZ composites had the lowest percolation threshold, followed by the Ni/YSZ and NiO/YSZ composites. When graphite was added with a nickel coating, the added porosity did not disrupt the nickel percolation network and allowed the nickel to occupy a larger effective volume compared to a composite made with similar sized solid nickel particles. When graphite was added to the composites, the electrical conductivity was reduced and the percolation threshold increased. <br /> Generally, the coefficient of thermal expansion (CTE) for Ni/YSZ composites are expected to follow the rule of mixtures prediction since the elastic properties for nickel and YSZ are similar. However when porosity is distributed unevenly between the YSZ and nickel phases, the CTE prediction will deviate from the rule of mixtures. When cornstarch was added to the NiGr/YSZ composites, the CTE increased as the amount of porosity in the YSZ phase increased. The CTE of the NiGr/YSZ composites followed the rule of mixtures indicating that the porosity was evenly distributed between the nickel and YSZ phases. For the other composite types, the measured CTE was higher than the rule of mixtures prediction suggesting that more porosity was contained within the YSZ phase.

There has always been a desire to develop industrial processes that minimize the resources they use, and the wastes they generate. The problem is when new guidelines are forced upon long established processes, such as solvent based coating operations. This means instead of integrating an emission reduction technology into the original design of the process, it is added on after the fact. This significantly increases the costs associated with treating emissions. In this work the ultimate goal is the design of an “add-on” abatement system to treat emissions from solvent based coating processes with high destruction efficiency, and lower costs than systems in current use. Since emissions from processes that utilize solvent based coatings are primarily comprised of volatile organic compounds (VOCs), the treatment of these compounds will be the focus. VOCs themselves contain a significant amount of energy. If these compounds could be destroyed by simultaneously extracting the energy they release, operational costs could be substantially reduced. This thesis examines the use of model-based design to develop and optimize a VOC abatement technology that uses a Solid Oxide Fuel Cell (SOFC) for energy recovery. The model was built using existing HYSYS unit operation models, and was able to provide a detailed thermodynamic and parametric analysis of this technology. The model was validated by comparison to published literature results and through the use of several Design of Experiment factorial analyses. The model itself illustrated that this type of system could achieve 95% destruction efficiency with performance that was superior to that of Thermal Oxidation, Biological Oxidation, or Adsorption VOC abatement technologies. This was based upon design criteria that included ten year lifecycle costs and operational flexibility, as well as the constraint of meeting (or exceeding) current regulatory thresholds.