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dc.contributor.authorZheng, Yaoyao
dc.date.accessioned2018-11-28T14:49:06Z
dc.date.available2018-11-28T14:49:06Z
dc.date.submitted2018-06-22
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/286023
dc.description.abstractThe thesis, entitled ‘Investigation of the conversion of fuels in the presence of solid oxygen carriers and the development of a plasma-assisted chemical looping system for H2 production’, presents the work of Yaoyao Zheng in the Department of Engineering, University of Cambridge, for the degree of Doctor of Philosophy. The thesis focused on chemical looping conversion of fuels, which employ oxygen carriers to supply oxygen, followed by the regeneration of the reduced oxygen carriers in air. Combustion of a Polish coal-derived char was first carried out in a fluidised bed reactor in the presence of Fe2O3 or ZrO2-supported Fe2O3. CO2 was introduced to the fluidised bed, to allow the char to be gasified in situ, prior to the reaction with the oxygen carriers. The presence of Fe2O3 did not alter the gasification step, given that the gasification of the char was free of external mass transfer limitation. A numerical model was developed to describe the gasification behaviour, as well as predicting the effect of CO on gasification. The inhibition effect of CO on char gasification was found more significant than expected. Combustion of biomass (wood pellets), by Fe2O3 or mayenite-supported CuO was studied in a fluidised bed. This was to understand how efficient the wood pellets were combusted by the oxygen carriers, as well as the distribution of the products. A tar measurement system, based on a plasma reactor, was first developed. With the developed measuring system, it was found that both Fe2O3 and mayenite-supported CuO were efficient for combusting wood pellets. Particularly, the CLOU nature of CuO makes mayenite-supported CuO a promising candidate for direct combustion, without introducing any reactive gaseous oxidant. The final part of the dissertation was focused on developing a plasma-assisted chemical looping system for H2-rich gas production (PCLH) from CH4 at mild temperatures (~ 673 K). SrFeO3-, Fe2O3, and Ni-doped SrFeO3- and Fe2O3 were investigated as the packing material. Total combustion of CH4 was observed in SrFeO3-. The addition of Ni onto SrFeO3- significantly improved the selectivity towards H2; whilst it was only active in the fresh cycle. Fe2O3 was found to be inert for converting CH4; however, the addition of Ni to form NiO/Fe2O3 dramatically improved H2 production and the reactivity maintained high for three redox cycles. The energy cost of such PCLH was comparable to that of water electrolysis.
dc.description.sponsorshipChina Scholarship Council Cambridge Trust Cambridge Philosophical Society EPSRC grant EP/L022427/1
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectchemical looping
dc.subjecthydrogen production
dc.subjectgasification
dc.subjectfuel conversion
dc.subjectplasma-assisted processing
dc.subjectNi-impregnated Fe2O3
dc.titleInvestigation of the conversion of fuels in the presence of solid oxygen carriers and the development of a plasma-assisted chemical looping system for H2 production
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentDepartment of engineering
dc.date.updated2018-11-28T11:43:15Z
dc.identifier.doi10.17863/CAM.33343
dc.publisher.collegeQueens' College Cambridge
dc.type.qualificationtitlePhD in Engineering
cam.supervisorScott, Stuart
cam.thesis.fundingfalse
rioxxterms.freetoread.startdate2019-11-28


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