Masters Theses

Date of Award

12-2003

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Mancil Milligan

Abstract

One of the major issues surrounding energy generation and use is the impact it has on the global climate Any process that includes the combustion of fossil fuels, such as coal, oil and natural gas, contains carbon dioxide among its exhaust products. The natural greenhouse effect is what makes the earth habitable, but if it is intensified by increased carbon dioxide concentration in the atmosphere, it may cause changes in global temperature, growing seasons or weather patterns that will alter the way of life for many people. The fact that carbon dioxide concentrations have increased by around 30 percent since the dawn of the industrial revolution has been shown by numerous studies. Because energy has such a central role in the global economy it is no simple matter to change the method of producing it. The infrastructure and technology in use today is geared toward the combustion of fossil fuels. Therefore, it seems logical to plot a path forward that uses fossil fuels in the generation of power while finding a way to mitigate the carbon dioxide emissions from such a process. The proposed MATIANT cycle is one way of meeting both these criteria. This process uses natural gas as its fuel, but allows for the removal of a carbon dioxide stream from the process, which can then be sequestered by any number of methods. In addition to using well established technology, any new method of generating power much provide a performance equal to that of conventional systems. This thesis analyzes the MATIANT cycle on a technical basis to determine if it is a feasible alternative to producing power. A model of the cycle is built using HYSYS process simulation software and then investigated for fuel use, efficiency and power output. These findings are compared the performance of a traditional power plant that has statepoints similar to those of the MATIANT cycle, such as maximum cycle pressure and temperature. In addition, the individual component performance of the MATIANT cycle is studied in order to gain a better understanding of the process. Furthermore, the MATIANT cycle is subjected to a parametric study whereby certain statepoints in the process are changed to gain an appreciation of their impact on cycle performance. The results of these parametric studies are compared to the base case MATIANT cycle performance. The parametric studies reveal that first law efficiency increases as the maximum cycle temperature increases and decreases as intercooler exit temperature increases. These parameters both have a more significant impact on the performance of the MATIANT cycle than changes in oxygen delivery temperature, fuel pressure or maximum cycle pressure. Cycle performance can be enhanced by adding an extra stage of compression and by eliminating the air separation unit powered by the MATIANT cycle. Compared to a simple cycle with similar process statepoints, the MATIANT cycle has a significantly higher first law efficiency, but the second law efficiency is appreciably lower. A component by component analysis of the MATIANT cycle reveals that the combustion chambers contribute the most irreversibility to the process, while the compressors are the least efficient components. A large amount of work is destroyed in the intercoolers, but they are useful to remove water from the process and to lower the compression power. Although further work on the MATIANT cycle is warranted, including a detailed economic analysis, this work proves that there is a technical basis to accepting the MATIANT cycle as an alternative to conventional power generation.

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