This study introduces an evaluation of the downstream utilization of oxygen produced by the hybrid sulfur process (HYS). Both technical and economic aspects were considered in the production of primarily synthesis gas and hydrogen. Both products could increase the economic potential of the hybrid sulfur process. Based on an assumed 500MWt pebble bed modular nuclear reactor, the volume of hydrogen and oxygen produced by the scaled down HYS was found to be 121 and 959 ton per day respectively. The partial oxidation plant (POX) could produce approximately 1840 ton synthesis gas per day based on the oxygen obtained from the HYS. The capital cost of the POX plant is in the order of $104 million (US dollars, Base year 2008). Compared to the capital cost of the HYS, this seems to be a relatively small additional investment. The production cost varied from a best case scenario $9.21 to a worst case scenario of $19.36 per GJ synthesis gas. The profitability analysis conducted showed favourable results, indicating that under the assumed conditions, and with 20 years of operation, a NPV of $87 mil. and an IRR of 19.5% could be obtained, for the assumed base case. The economic sensitivity analysis conducted, provided insight into the upper and lower limitations of favourable operation. The second product that could be produced was hydrogen. With the addition of a water gas shift and a pressure swing adsorption process to the POX, it was found that an additional 221 ton of hydrogen per day could be produced. The hydrogen could be produced in the best case at $2.34/kg and in the worst case at $3.76/kg. The investment required would be in the order of $50 million. The profitability analysis for the base case analysis predicts an NPV of $206 million and a high IRR of 23.0% under the assumed conditions. On financial grounds it therefore seemed that the hydrogen production process was favourable. The thermal efficiency of the synthesis gas production section was calculated and was in good agreement with that obtained from literature. The hydrogen production section’s thermal efficiency was compared to that of steam methane reforming of natural gas (SMR) and it was found that the efficiencies were comparable but the SMR process was superior. The hydrogen production capacity of the HYS process was increased by a factor of 1.83. This implied that for every 1 kg of hydrogen produced by the HYS an additional 1.83 kg was produced by the proposed process addition. This lowers the cost of hydrogen produced by the HYS from $6.83 to the range of approximately $3.93 - $4.85/kg. In the event of a global hydrogen economy, traditional production methods could very well be supplemented with new and innovative methods. The integration of the wellknown methods incorporated with the new nuclear based methods of hydrogen production and chemical synthesis could facilitate the smooth transition from fossil fuel based to environmentally friendly methods. This study presents one possible integration method of nuclear based hydrogen production and conventional processing methods. This process is technically possible, efficient and economically feasible. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

The production of synthetic fuels (synfuels) in coal–to–liquids (CTL) facilities has contributed to global warming due to the huge CO2 emissions of the process. This corresponds to inefficient carbon conversion, a problem growing in importance particularly given the limited lifespan of coal reserves. These simultaneous challenges of environmental sustainability and energy security associated with CTL facilities have been defined in earlier studies. To reduce the environmental impact and improve the carbon conversion of existing CTL facilities, this paper proposes the concept of a nuclear–assisted CTL plant where a hybrid sulphur (HyS) plant powered by 10 modules of the high temperature nuclear reactor (HTR) splits water to produce hydrogen (nuclear hydrogen) and oxygen, which are in turn utilised in the CTL plant. A synthesis gas (syngas) plant mass–analysis model described in this paper demonstrates that the water–gas shift (WGS) and combustion reactions occurring in hypothetical gasifiers contribute 67% and 33% to the CO2 emissions, respectively. The nuclear–assisted CTL plant concept that we have developed is entirely based on the elimination of the WGS reaction, and the consequent benefits are investigated. In this kind of plant, the nuclear hydrogen is mixed with the outlet stream of the Rectisol unit and the oxygen forms part of the feed to the gasifier. The significant potential benefits include a 75% reduction in CO2 emissions, a 40% reduction in the coal requirement for the gasification plant and a 50% reduction in installed syngas plant costs, all to achieve the same syngas output. In addition, we have developed a financial model for use as a strategic decision analysis (SDA) tool that compares the relative syngas manufacturing costs for conventional and nuclear–assisted syngas plants. Our model predicts that syngas manufactured in the nuclear–assisted CTL plant would cost 21% more than that produced in the conventional CTL plant when the average cost of producing nuclear hydrogen is US$3/kg H2. The model also evaluates the cost of CO2 avoided as $58/t CO2. Sensitivity analyses performed on the costing model reveal, however, that the cost of CO2 avoided is zero at a hydrogen production cost of US$2/kg H2 or at a delivered coal cost of US$128/t coal. The economic advantages of the nuclear–assisted plant are lost above the threshold cost of $100/t CO2. However, the cost of CO2 avoided in our model works out to below this threshold for the range of critical assumptions considered in the sensitivity analyses. Consequently, this paper demonstrates the practicality, feasibility and economic attractiveness of the nuclear–assisted CTL plant. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.

This study introduces an evaluation of the downstream utilization of oxygen produced by the hybrid sulfur process (HYS). Both technical and economic aspects were considered in the production of primarily synthesis gas and hydrogen. Both products could increase the economic potential of the hybrid sulfur process. Based on an assumed 500MWt pebble bed modular nuclear reactor, the volume of hydrogen and oxygen produced by the scaled down HYS was found to be 121 and 959 ton per day respectively. The partial oxidation plant (POX) could produce approximately 1840 ton synthesis gas per day based on the oxygen obtained from the HYS. The capital cost of the POX plant is in the order of $104 million (US dollars, Base year 2008). Compared to the capital cost of the HYS, this seems to be a relatively small additional investment. The production cost varied from a best case scenario $9.21 to a worst case scenario of $19.36 per GJ synthesis gas. The profitability analysis conducted showed favourable results, indicating that under the assumed conditions, and with 20 years of operation, a NPV of $87 mil. and an IRR of 19.5% could be obtained, for the assumed base case. The economic sensitivity analysis conducted, provided insight into the upper and lower limitations of favourable operation. The second product that could be produced was hydrogen. With the addition of a water gas shift and a pressure swing adsorption process to the POX, it was found that an additional 221 ton of hydrogen per day could be produced. The hydrogen could be produced in the best case at $2.34/kg and in the worst case at $3.76/kg. The investment required would be in the order of $50 million. The profitability analysis for the base case analysis predicts an NPV of $206 million and a high IRR of 23.0% under the assumed conditions. On financial grounds it therefore seemed that the hydrogen production process was favourable. The thermal efficiency of the synthesis gas production section was calculated and was in good agreement with that obtained from literature. The hydrogen production section’s thermal efficiency was compared to that of steam methane reforming of natural gas (SMR) and it was found that the efficiencies were comparable but the SMR process was superior. The hydrogen production capacity of the HYS process was increased by a factor of 1.83. This implied that for every 1 kg of hydrogen produced by the HYS an additional 1.83 kg was produced by the proposed process addition. This lowers the cost of hydrogen produced by the HYS from $6.83 to the range of approximately $3.93 - $4.85/kg. In the event of a global hydrogen economy, traditional production methods could very well be supplemented with new and innovative methods. The integration of the wellknown methods incorporated with the new nuclear based methods of hydrogen production and chemical synthesis could facilitate the smooth transition from fossil fuel based to environmentally friendly methods. This study presents one possible integration method of nuclear based hydrogen production and conventional processing methods. This process is technically possible, efficient and economically feasible. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

The production of synthetic fuels (synfuels) in coal–to–liquids (CTL) facilities has contributed to global warming due to the huge CO2 emissions of the process. This corresponds to inefficient carbon conversion, a problem growing in importance particularly given the limited lifespan of coal reserves. These simultaneous challenges of environmental sustainability and energy security associated with CTL facilities have been defined in earlier studies. To reduce the environmental impact and improve the carbon conversion of existing CTL facilities, this paper proposes the concept of a nuclear–assisted CTL plant where a hybrid sulphur (HyS) plant powered by 10 modules of the high temperature nuclear reactor (HTR) splits water to produce hydrogen (nuclear hydrogen) and oxygen, which are in turn utilised in the CTL plant. A synthesis gas (syngas) plant mass–analysis model described in this paper demonstrates that the water–gas shift (WGS) and combustion reactions occurring in hypothetical gasifiers contribute 67% and 33% to the CO2 emissions, respectively. The nuclear–assisted CTL plant concept that we have developed is entirely based on the elimination of the WGS reaction, and the consequent benefits are investigated. In this kind of plant, the nuclear hydrogen is mixed with the outlet stream of the Rectisol unit and the oxygen forms part of the feed to the gasifier. The significant potential benefits include a 75% reduction in CO2 emissions, a 40% reduction in the coal requirement for the gasification plant and a 50% reduction in installed syngas plant costs, all to achieve the same syngas output. In addition, we have developed a financial model for use as a strategic decision analysis (SDA) tool that compares the relative syngas manufacturing costs for conventional and nuclear–assisted syngas plants. Our model predicts that syngas manufactured in the nuclear–assisted CTL plant would cost 21% more than that produced in the conventional CTL plant when the average cost of producing nuclear hydrogen is US$3/kg H2. The model also evaluates the cost of CO2 avoided as $58/t CO2. Sensitivity analyses performed on the costing model reveal, however, that the cost of CO2 avoided is zero at a hydrogen production cost of US$2/kg H2 or at a delivered coal cost of US$128/t coal. The economic advantages of the nuclear–assisted plant are lost above the threshold cost of $100/t CO2. However, the cost of CO2 avoided in our model works out to below this threshold for the range of critical assumptions considered in the sensitivity analyses. Consequently, this paper demonstrates the practicality, feasibility and economic attractiveness of the nuclear–assisted CTL plant. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.