Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System

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dc.contributor.advisorFletcher, Jacken_ZA
dc.contributor.authorSteynberg, Andre Peteren_ZA
dc.date.accessioned2015-07-02T08:35:22Z
dc.date.available2015-07-02T08:35:22Z
dc.date.issued2014en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractA set of operating conditions was identified with the potential to enable improved slurryphase reactor productivity for hydrocarbon production using Fischer-Tropsch synthesis. Compared to the most relevant prior art publication, this requires operation at higher gas velocity, higher catalyst concentration and at higher temperature and/or pressure. The closest prior art proposal was published by Van der Laan et al. (1999) and a target was set to improve the reactor productivity by at least 50 %, relative to this reference, while also ensuring stable catalyst performance. Prediction of gas holdup in the reactor is essential to determine the reactor productivity and previous correlations used to predict gas holdup are potentially unreliable for extrapolation to the new proposed conditions. A new approach is adapted, from previous theoretical approaches, to provide a more fundamental and reliable basis for gas holdup prediction. Referred to as the ¡®adapted two-phase theory¡¯ it predicts the gas holdup at any slurry solids concentration using data from a representative solids-free liquid. This approach is shown to provide accurate predictions for paraffinic liquids using data covering a wide range of solids concentrations. Two laboratory reactor experiments were performed, at 260 and 270 ¢ªC, to characterise the selected catalyst performance at conditions relevant to the newly proposed operating regime. An achievable reactor performance was calculated corresponding to the catalyst performance from the experiment at 270 ¢ªC and using the new approach to predict gas holdup. Compared to the proposal by Van der Laan et al. (1999), a reactor with a given diameter is able to produce almost double the amount of product (94 % more with a lower slurry bed height). This is achievable by using higher catalyst concentrations and, most importantly, using a higher operating temperature. The undesirable methane selectivity, at or below 4 %, is still acceptable when operating at 270 ¢ªC. In spite of the higher reactor productivity with increasing temperature, the optimum operating temperature, in the range from 250 to 270 ¢ªC, may depend on the selectivity to the desired hydrocarbon products. The scope for further potential reactor productivity improvement is described. More work is needed to accurately quantify the selected iron catalyst selectivity performance, in the proposed temperature range, but the hydrocarbon selectivity was found to be insensitive to other operating conditions (i.e. pressure and gas composition). It is now possible to better quantify the reactor productivity in the trade-offs which are made with the selectivity performance and the overall plant design configuration which requires recycle of carbon dioxide to the methane reformers to adjust feed gas H2/CO ratio for natural gas applications. The carbon dioxide selectivity for the selected catalyst at the conditions tested was found to be too high for gas-to-liquid (GTL) applications using a natural gas feed.en_ZA
dc.identifier.apacitationSteynberg, A. P. (2014). <i>Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering. Retrieved from http://hdl.handle.net/11427/13279en_ZA
dc.identifier.chicagocitationSteynberg, Andre Peter. <i>"Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2014. http://hdl.handle.net/11427/13279en_ZA
dc.identifier.citationSteynberg, A. 2014. Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Steynberg, Andre Peter AB - A set of operating conditions was identified with the potential to enable improved slurryphase reactor productivity for hydrocarbon production using Fischer-Tropsch synthesis. Compared to the most relevant prior art publication, this requires operation at higher gas velocity, higher catalyst concentration and at higher temperature and/or pressure. The closest prior art proposal was published by Van der Laan et al. (1999) and a target was set to improve the reactor productivity by at least 50 %, relative to this reference, while also ensuring stable catalyst performance. Prediction of gas holdup in the reactor is essential to determine the reactor productivity and previous correlations used to predict gas holdup are potentially unreliable for extrapolation to the new proposed conditions. A new approach is adapted, from previous theoretical approaches, to provide a more fundamental and reliable basis for gas holdup prediction. Referred to as the ¡®adapted two-phase theory¡¯ it predicts the gas holdup at any slurry solids concentration using data from a representative solids-free liquid. This approach is shown to provide accurate predictions for paraffinic liquids using data covering a wide range of solids concentrations. Two laboratory reactor experiments were performed, at 260 and 270 ¢ªC, to characterise the selected catalyst performance at conditions relevant to the newly proposed operating regime. An achievable reactor performance was calculated corresponding to the catalyst performance from the experiment at 270 ¢ªC and using the new approach to predict gas holdup. Compared to the proposal by Van der Laan et al. (1999), a reactor with a given diameter is able to produce almost double the amount of product (94 % more with a lower slurry bed height). This is achievable by using higher catalyst concentrations and, most importantly, using a higher operating temperature. The undesirable methane selectivity, at or below 4 %, is still acceptable when operating at 270 ¢ªC. In spite of the higher reactor productivity with increasing temperature, the optimum operating temperature, in the range from 250 to 270 ¢ªC, may depend on the selectivity to the desired hydrocarbon products. The scope for further potential reactor productivity improvement is described. More work is needed to accurately quantify the selected iron catalyst selectivity performance, in the proposed temperature range, but the hydrocarbon selectivity was found to be insensitive to other operating conditions (i.e. pressure and gas composition). It is now possible to better quantify the reactor productivity in the trade-offs which are made with the selectivity performance and the overall plant design configuration which requires recycle of carbon dioxide to the methane reformers to adjust feed gas H2/CO ratio for natural gas applications. The carbon dioxide selectivity for the selected catalyst at the conditions tested was found to be too high for gas-to-liquid (GTL) applications using a natural gas feed. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System TI - Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System UR - http://hdl.handle.net/11427/13279 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/13279
dc.identifier.vancouvercitationSteynberg AP. Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/13279en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Chemical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemical Engineeringen_ZA
dc.titleProcess intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor Systemen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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