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Analysis of a natural gas combined cycle powerplant modeled for carbon capture with variance of oxy-combustion characteristics

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dc.contributorWoodbury, Keith A.
dc.contributorWilliamson, Derek G.
dc.contributor.advisorMidkiff, K. Clark
dc.contributor.authorBreshears, Matthew Joseph
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2017-03-01T14:41:32Z
dc.date.available2017-03-01T14:41:32Z
dc.date.issued2011
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractThe world's ever growing demand for energy has resulted in increased consumption of fossil fuels for electricity generation. The emissions from this combustion have contributed to increasing ambient levels of carbon dioxide in the atmosphere. Many efforts have been made to curb and reduce carbon dioxide emissions in the most efficient manner. The computer process modeling software CHEMCAD was used to model a natural gas combined cycle powerplant for carbon capture and sequestration. Equipment for two proven carbon capture techniques, oxy-combustion and post-combustion amine scrubbing, were modeled. The necessary components modeled included an air separation unit, powerplant, amine scrubbing unit, and a carbon dioxide compression and drying unit. The oxygen concentration in the oxidizer supplied to the powerplant was varied from ambient air, 21%, to nearly pure oxygen, 99.6%. Exhaust gas recirculation was incorporated to maintain a constant combustion temperature. At ambient conditions no air separation unit was necessary and all carbon capture was provided by the amine scrubbing unit. At concentrations ranging from 22 - 99% both oxy-combustion and amine scrubbing techniques are used at inversely varying degrees. At 99.6%, no amine scrubbing unit was necessary. As the oxygen concentration was varied operational parameters were investigated with the goal of identifying optimum operational conditions. Across the varying oxygen concentrations, the First Law efficiency losses ranged from 3.3 - 13.6%. The optimal operational point occurred when ambient air was supplied and exhaust gas recirculation was utilized for flame temperature control. A Second Law efficiency of 52.2% was maximized at an oxygen concentration of 22%. This corresponds to a 2.28% reduction in Second Law efficiency. An exergy analysis of each component identified the air separation unit as the component where the most improvements are possible. At 99% oxygen concentration, the Second Law efficiency of the air separation unit was 3%. Through modeling a natural gas combined cycle powerplant for carbon capture and varying the oxy-combustion characteristics, valuable information was gained in the understanding of operational losses associated with carbon capture.en_US
dc.format.extent113 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0000609
dc.identifier.otherBreshears_alatus_0004M_10606
dc.identifier.urihttps://ir.ua.edu/handle/123456789/1114
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectMechanical engineering
dc.subjectAlternative energy
dc.titleAnalysis of a natural gas combined cycle powerplant modeled for carbon capture with variance of oxy-combustion characteristicsen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Mechanical Engineering
etdms.degree.disciplineMechanical Engineering
etdms.degree.grantorThe University of Alabama
etdms.degree.levelmaster's
etdms.degree.nameM.S.

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