Study of oxy-fuel power plants with CO2 capture

Abstract

Consulta en la Biblioteca ETSI Industriales (8411)

[EN] It is well known that the energy demand in the world is constantly and quickly increasing. For this reason, it is needed to develop new ways for more efficient, economical and environmentally sustainable of energy production. Furthermore, society is forcing countries to reduce carbon emissions and to show an environmental friendly image. This makes so many companies and governments to reconsider the conventional ways for power generation. Furthermore, nuclear energy is not appreciated in most countries, whereas extra energy is needed in the short term. So, all new methods of electricity generation without carbon dioxide emissions could have an important future. Oxy-fuel power plants with CO2 capture are a chance to reduce carbon dioxide emissions and a technology with a promising future. They could be worthwhile and competitive in a short period of time. The first aim of this study is basically to do a thorough literature review to evaluate the most recent advances in oxy-fuel power plants with CO2 capture. The thesis contains a description of the process, the sources of pollutant emissions, the environmental impacts and the technology used to control and to mitigate the effects of these pollutants. Then, the Spanish and European legislation concerning the oxy-fuel power plants with CO2 capture is explained. After that, the study is focused on oxy-fuel power plants modelling and simulation with the software Aspen HYSYS. The last aim of the project is to investigate new ideas and the economic feasibility of the system. In this way, it will become necessary to find the optimal O2 mass fraction in the air separation unit and the optimal recycle rate for the flue gas to furnace. The optimisation results show that the optimal O2 mass fraction in the ASU is 98.45 %. The recycle rate for the flue gas to furnace is 68 %, which has not changed after the optimisation process. The key issues for the oxy-fuel technology are to reduce the Air Separation Unit (ASU) power consumption and to try the ASU and the CO2 capture unit heat train integration in the whole process. Besides, the economic analysis of the process shows that oxy-fuel power plants with CO2 capture are viable only if CO2 capture is needed and externally supported. However, they are not competitive with conventional post-combustion plants. If the carbon dioxide capture is neither required nor monetary supported, oxy-fuel power plants are not able to make money. Nevertheless, for the oxy-fuel case, only improvements in the steam turbine technology have been accounted for. Therefore, there is still a huge potential to improve process parts related to the oxy-fuel and air separation processes. Furthermore, if the high initial capital cost of oxy-fuel power plants can be reduced, they will become competitive rapidly.