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Item type:Publication, Access status: without files , Energetische Untersuchung des Gesamtprozesses eines erdgasbefeuerten Gas- und Dampfturbinenkraftwerks mit Oxyfuel-TechnologiePublicationtype: Doctoral Thesis138 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Oxyfuel combustion for CO2 capture in power plants(Elsevier, 2015-08-04); ; ; ; Oxyfuel combustion is one of the leading technologies considered for capturing CO from power plants with CCS. This involves the process of burning the fuel with nearly pure oxygen instead of air. In order to control the flame temperature, some part of the flue gas are recycled back into the furnace/boiler. Since the publication of the Special Report on CO Capture and Storage by the International Panel for Climate Change (IPCC, 2005), the development of oxyfuel combustion technology has progressed significantly and could be considered at par in terms of technology maturity as compared to other leading CO capture technologies. This paper presents an overview to the current state-of-the-art technology on the development of oxyfuel combustion applied to (a) PC and CFB coal fired power plants and (b) gas turbine based power plant. It should be noted that it is not the intention of this paper to provide a comprehensive review but to present what have been achieved in the past 10 years of RD&D efforts. For coal fired power plant using oxyfuel combustion, this paper primarily presents the different development aspects of the burners and boilers (combustion and heat transfer), emissions, operation of the plant (i.e. start-up and turndown) and its integration to the ASU and CPU. For gas turbine based power plant using oxyfuel combustion, the different GT cycles are described, looking at the different aspects in combustion, emissions, cycle efficiency and development of the turbomachineries. Also presented in this paper is a snapshot to what we have learned from the operation of the different large-scale pilot plants and development of large scale demonstration projects worldwide. The paper concludes by presenting the potential of this technology and highlighting the importance of realizing large scale demonstration plant as a necessary step to achieve its ultimate goal of technology commercialization. 2 2 2Publicationtype: Journal Article232 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Comparison of natural gas combined cycle power plants with post combustion and oxyfuel technology at different CO₂ capture ratesWithin this work a natural gas-fired combined cycle plant is investigated with post-combustion CO₂ capture (PCC) and as a semi-closed oxyfuel combustion combined cycle (SCOC-CC) using process simulation tools. In most studies the CO₂ capture rate of PCC units is set to 90% while the SCOC-CC is often considered for zero emission plants. To allow a comparison between the processes the capture rate needs to be taken into account. If a certain CO₂ emission value is required a different capture rate may be economically attractive. The effect of the capture rate is investigated from 60% to 97.5% for PCC and from 75% to 100% for the SCOC-CC. For PCC the capture rate has a strong influence on the efficiency penalty. For a broad range of capture rates the specific heat duty is found to be approx. constant. However, for very high capture rates the heat duty strongly increases. The efficiency penalty of the SCOC-CC is much less affected by the chosen capture rate, because the duty of the air separation unit (ASU) is independent on the capture rate. However to achieve a sufficient CO₂ purity a reduced capture rate can be necessary. The processes are compared regarding the loss of electrical energy per kg CO₂ captured. PCC has a significantly lower specific loss for low capture rates of approx. 0.38 kWhel/kg CO₂ compared to the SCOC-CC with more than 0.48 kWhel/kg CO₂. For capture rates of > 90% the losses of both processes approach each other. With high purity oxygen the SCOC-CC can achieve a capture rate of 100% as well as a CO₂ purity of >96 vol.-% at a specific loss of 0.49 kWhel/kg CO₂.Publicationtype: Conference PaperScopus© Citations 38 488 455 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimisation potentials for the heat recovery in a semi-closed oxyfuel-combustion combined cycle with a reheat gas turbineSemi-closed oxyfuel-combustion combined cycle plants are one possibility to realise CCS technologies with natural gas-fired power plants. Due to the recirculation of exhaust gas the working fluid in the gas turbine consists mainly of CO2. This leads to the necessity for an increased pressure ratio to achieve the efficiency and the exhaust gas temperatures of conventional gas turbines. In this work a conventional natural gas-fired combined cycle plant with a reheat gas turbine modified for oxyfuel operation will be presented. As it is assumed that the necessary pressure ratio is not realisable with axial compressors two different scenarios are considered. On the one hand the pressure ratio is the same as in the conventional process and on the other hand the pressure ratio is set to an assumed maximum of 60. The exhaust gas temperature lies significantly above the values of the conventional plant. Generally the higher pressure ratio results in a higher net efficiency of the plant. An unchanged heat recovery process results in a loss of efficiency of at least 9.3 to 10.8 %-pts. depending on the pressure ratio. Increasing the steam parameters can achieve a reduction of this loss ranging from 0.5 %-pts for the high pressure ratio to 1.0 %-pts for the low pressure ratio. An alternative approach for the heat recovery is the application of an internal recuperator in the gas turbine. When the achievable pressure ratio is far from the optimum value, as in the low pressure ratio case, this approach can lead to significantly lower losses of 9.1 %-pts. With a higher pressure ratio the effects of the optimisation options are similar.Publicationtype: Conference PaperScopus© Citations 9 316 235