The Experts below are selected from a list of 2571 Experts worldwide ranked by ideXlab platform
Alfons Kather - One of the best experts on this subject based on the ideXlab platform.
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flue gas concentrations and efficiencies of a coal fired Oxyfuel power plant with circulating fluidised bed combustion
Energy Procedia, 2013Co-Authors: Matthias Weng, Claas Gunther, Alfons KatherAbstract:Abstract In contrast to an Oxyfuel process with pulverised coal (PC) firing, possible advantages of a circulating fluidised bed combustion (CFBC) are the in-furnace sulphur dioxide removal no additional sulphur dioxide removal downstream the steam generator might be necessary and the feasibility for concepts with a reduced flue gas recirculation. In [1] design conditions for the overall process of an Oxyfuel CFBC with highest flue gas recirculation up to 75% are compared to concepts with less recycled flue gas. Compared to [1], this work is not focussed on design aspects of the steam generator but rather on the changing structure of auxiliary power demand of an integrated overall process caused by a reduced flue gas recirculation. At full load operation and under realistic boundary conditions achievable efficiencies of an Oxyfuel CFBC will be examined and compared to the PC-fired Oxyfuel process.
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evaluation and comparison of the part load behaviour of the co2 capture technologies Oxyfuel and post combustion
Energy Procedia, 2013Co-Authors: Volker Roeder, Christoph Hasenbein, Alfons KatherAbstract:Abstract The rising share of fluctuating renewable energies increasingly demand flexible and part load operation of fossil-fuelled power plants with and without CCS. In this work the part load behaviour of the Oxyfuel and the post-combustion CO2 capture processes are evaluated and compared. The net efficiency of the conventional hard-coal-fired power plant decreases from 45.2% at full load to 41.6% at 40% load. The net efficiency with post-combustion CO2 capture using 7 m MEA as solvent decreases to 34.7% at full load and 30.2% at 40% load. The Oxyfuel process reaches in turn a net efficiency of 36.6% at full load and 32.3% at 40% load and shows therefore a benefit of 1.9%-points at full load compared to the post- combustion CO2 capture with MEA. The efficiency advantage of the Oxyfuel process compared to the post-combustion CO2 capture process remains constant at part load.
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restrictions and limitations for the design of a steam generator for a coal fired Oxyfuel power plant with circulating fluidised bed combustion
Energy Procedia, 2013Co-Authors: Claas Gunther, Matthias Weng, Alfons KatherAbstract:Abstract As general restrictions for the design of Oxyfuel pulverised coal-fired (PC) steam generators are commonly known, the purpose of this work is to show general restrictions for the design of an Oxyfuel coal-fired steam generator using a circulating fluidised bed combustor (CFBC) with external heat exchangers (EHEs). For the CFBC restrictions result on the one hand out of the used fuels composition. On the other hand certain restrictions out of state-of-the-art and steam generator geometries have to be considered within the design.
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comparative thermodynamic analysis and integration issues of ccs steam power plants based on oxy combustion with cryogenic or membrane based air separation
Energy Procedia, 2009Co-Authors: Imo Pfaff, Alfons KatherAbstract:Abstract When realizing CSS steam power plants based on oxy-combustion, the energy demand for oxygen production is one of the main causes for efficiency losses. This comparative study focuses on the impact of the air separation technology - cryogenic as well as high temperature membrane based - on the efficiency of a coal-fired Oxyfuel steam power plant. As a result of this study both show comparable efficiency potentials whereas the membrane based technology needs a higher degree of integration into the power cycle to compete efficiencies of the Oxyfuel power plant with cryogenic ASU.
Günter Scheffknecht - One of the best experts on this subject based on the ideXlab platform.
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Oxyfuel combustion for co2 capture in power plants
International Journal of Greenhouse Gas Control, 2015Co-Authors: Rohan Stanger, Manoj Paneru, Simon Grathwohl, Max Weidmann, Denny Mcdonald, Kari Myohanen, Reinhold Spörl, Günter Scheffknecht, T F Wall, Jouni RitvanenAbstract:Oxyfuel combustion is one of the leading technologies considered for capturing CO2 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 CO2 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 CO2 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.
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Oxyfuel technology no reduction during oxy oil shale combustion
Fuel, 2014Co-Authors: Leema A Almakhadmeh, J Maier, Günter ScheffknechtAbstract:Abstract Nitrogen oxides are one of the major environmental problems arising from fossil fuels combustion. Oxyfuel combustion is one of the most promising clean coal technologies for pulverized fuel-fired power plants to control and avoid CO 2 emissions; with this technology NO x emissions are significantly reduced. Due to the importance of oil shale utilization in Jordan and all over the world, this study continues with our previous work on oil shale combustion. Unstaged and staged air-firing and Oxyfuel combustion were carried out using Jordanian oil shale collected from El-Lajjun area. The reduction of simulated recycled NO has been investigated in a 20 kW vertical reactor. The actual situation has been simulated by injecting NO in the reactor through the burner. It was found that the simulated recycled NO reduction efficiency is affected by the media and the mode of firing. The simulated recycled NO is reduced efficiently (60–70%) during unstaged Oxyfuel combustion as well as air-firing of El-Lajjun oil shale. The reduction of the injected NO is more efficient with staging compared to unstaged combustion mode for both air-firing and Oxyfuel combustion. The reduction of the injected NO for combustion in air ranges from 61% (without staging) to 100% (with staging) whereas for combustion in 27% O 2 /73% CO 2 , it ranges from 57% (without staging) to 100% (with staging). Moreover, El-Lajjun oil shale ashes are characterized as being high in CaO and SiO 2 , low in Al 2 O 3 , SO 3 , and P 2 O 5 and with minor amounts of F 2 O 3 , MgO, Na 2 O, K 2 O, and TiO 2 .
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Oxyfuel technology no reduction during oxy oil shale combustion
Fuel, 2014Co-Authors: Leema A Almakhadmeh, J Maier, Günter ScheffknechtAbstract:Abstract Nitrogen oxides are one of the major environmental problems arising from fossil fuels combustion. Oxyfuel combustion is one of the most promising clean coal technologies for pulverized fuel-fired power plants to control and avoid CO 2 emissions; with this technology NO x emissions are significantly reduced. Due to the importance of oil shale utilization in Jordan and all over the world, this study continues with our previous work on oil shale combustion. Unstaged and staged air-firing and Oxyfuel combustion were carried out using Jordanian oil shale collected from El-Lajjun area. The reduction of simulated recycled NO has been investigated in a 20 kW vertical reactor. The actual situation has been simulated by injecting NO in the reactor through the burner. It was found that the simulated recycled NO reduction efficiency is affected by the media and the mode of firing. The simulated recycled NO is reduced efficiently (60–70%) during unstaged Oxyfuel combustion as well as air-firing of El-Lajjun oil shale. The reduction of the injected NO is more efficient with staging compared to unstaged combustion mode for both air-firing and Oxyfuel combustion. The reduction of the injected NO for combustion in air ranges from 61% (without staging) to 100% (with staging) whereas for combustion in 27% O 2 /73% CO 2 , it ranges from 57% (without staging) to 100% (with staging). Moreover, El-Lajjun oil shale ashes are characterized as being high in CaO and SiO 2 , low in Al 2 O 3 , SO 3 , and P 2 O 5 and with minor amounts of F 2 O 3 , MgO, Na 2 O, K 2 O, and TiO 2 .
Chuguang Zheng - One of the best experts on this subject based on the ideXlab platform.
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mercury adsorption and oxidation over magnetic biochar in Oxyfuel combustion atmosphere impact of enriched co2 and h2o
Fuel, 2019Co-Authors: Yuming Zhou, Yongchun Zhao, Junying Zhang, Chuguang ZhengAbstract:Abstract The abatement of mercury from Oxyfuel combustion flue gas should be paid special attention due to the metal embrittlement and aluminum corrosion for CO2 compression device. The effects of enriched CO2 and H2O in Oxyfuel combustion atmosphere on mercury removal over biochar (BC) and magnetic biochar (MBC) was studied. Hg0 was firstly captured by physical adsorption and then oxidized to various mercury compounds. A large amount of organic groups, especially C O group, were formed with the assistance of enriched CO2. As a result, more Hg0 was oxidized over BC and more organic Hg (Hg-OM) was formed on BC and MBC. However, the content of chemisorbed oxygen on MBC was reduced under Oxyfuel combustion atmosphere, hence reducing the formation of HgO on MBC compared with air combustion atmosphere. The enriched H2O significantly inhibited the removal of mercury over MBC. Chlorine was demonstrated as the most significant active components for mercury removal, since HgCl2 was the dominant species on MBC. This work clarified the effects of enriched CO2 and H2O on Hg0 adsorption over BC and MBC, which is essential for further improving the adsorption activity.
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mercury emission and speciation in fly ash from a 35 mwth large pilot boiler of Oxyfuel combustion with different flue gas recycle
Fuel, 2017Co-Authors: Jianping Yang, Yongxin Feng, Yongchun Zhao, Kai Xu, Junying Zhang, Jun Xiang, Shihong Zhang, Yi Zhang, Chuguang ZhengAbstract:Abstract The behaviour of mercury is investigated in a 35 MW th large pilot boiler of Oxyfuel combustion with dry and wet flue gas recycle (FGR). The mercury species in fly ash particles as well as the involved reaction mechanism are systematically investigated. The results suggest that higher concentration of gas–phase mercury (Hg g ) is contained in Oxyfuel combustion flue gas. The conversion of Hg g to particulate associated mercury (Hg p ) is enhanced in Oxyfuel combustion. Different mercury species are presented in fly ash collected from air and Oxyfuel combustion: trigonal red HgS is the main mercury species in air combustion; mercury bound to organic matter (Hg–OM) and trigonal red HgS are both dominant in the samples from Oxyfuel combustion. The prominent difference is the significantly increase of Hg–OM in Oxyfuel combustion atmosphere. The Oxyfuel combustion atmosphere would favor the formation of oxygen–rich functional groups, especially the C O group, which is responsible for the adsorption of mercury and formation of Hg–OM in fly ash.
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methane combustion in mild Oxyfuel regime influences of dilution atmosphere in co flow configuration
Energy, 2017Co-Authors: Sheng Chen, Chuguang ZhengAbstract:MILD (moderate or intense low oxygen dilution) Oxyfuel combustion is a recently proposed clean combustion mode which can remedy the shortcomings of the standard Oxyfuel combustion technology. Nowadays most available studies on MILD Oxyfuel combustion focus on how to realize this new combustion regime in O2/CO2 atmosphere. The open research on methane MILD Oxyfuel combustion in O2/H2O atmosphere is quite sparse. In the present work, we carry out a comprehensive comparison study on methane MILD Oxyfuel combustion in different dilution atmosphere for the first time. The JHC (jet in hot co-flow) burner is adopted as a research prototype. The investigation is based on numerical simulation, so firstly the adopted numerical approach is validated by some experimental data in open literature. The numerical comparison is conducted by varying the mass fraction of oxygen in the co-flow and the temperature of the hot co-flow, two key parameters affecting fine reaction structures in JHC. Through the present investigation, a number of findings are reported for the first time and some conclusions presented in previous publications are checked with analyses, especially on some conflicted claims between the previous publications. In addition, several new questions are raised, which may inspire further research activities in future.
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A numerical investigation on flame stability of oxy-coal combustion: Effects of blockage ratio, swirl number, recycle ratio and partial pressure ratio of oxygen
International Journal of Greenhouse Gas Control, 2017Co-Authors: Sheng Chen, Stanley Santos, Chuguang ZhengAbstract:Abstract Keeping the flame stable and having the appropriate flame shape is essential in operating an Oxyfuel combustion coal fired power plant with CO 2 capture. This is more critical if the boiler is required to operate in full and partial thermal load with varying volume of flue gas recycled. Therefore, in designing the Oxyfuel combustion burner, it is important to evaluate the burner stability, shape structure and flame type. This work presents numerical investigation of a burner designed for Oxyfuel combustion coal fired boiler. The study evaluated the effects of the blockage ratio, swirl number, flue gas recycle ratio, and oxygen partial pressure in the primary RFG stream on the flame stability, type, shape and structure. The model results were validated against experimental data obtained from a novel Oxyfuel combustion burner designed and operated in a 2.5MWt test pilot facility. The model developed for this study incorporated a modified chemical reaction mechanism that allows the addition of CO and Boudouard reaction that is considered significant in an Oxyfuel combustion flame. The results show that the stability of an Oxyfuel combustion flame is greatly improved by having a moderate to strong internal recirculation zone to produce a Type-II flame; and could also be easily destabilized by a high velocity jet of unburned carbon/char as illustrated by a dark central region emanating from the centre of the burner. Additionally, it could also be illustrated that the swirl number and flue gas recycle ratio have a strong influence to the formation of the central dark region along the centerline of the burner. It could be concluded that maintaining the flame Type-II over the whole range of thermal load should maintain the necessary flame stability appropriate to an Oxyfuel combustion boiler.
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methane combustion in various regimes first and second thermodynamic law comparison between air firing and Oxyfuel condition
Energy, 2016Co-Authors: Yongxin Feng, Kai Xu, Sheng Chen, Chuguang ZhengAbstract:MILD Oxyfuel combustion has been attracting increasing attention as a promising clean combustion technology. How to design a pathway to reach MILD Oxyfuel combustion regime and what can provide a theoretical guide to design such a pathway are two critical questions that need to be answered. So far there has been no open literature on these issues. A type of combustion regime classification map proposed in our previous work, based on the so-called ”Hot Diluted Diffusion Ignition” (HDDI) configuration, is adopted here as a simple but useful tool to solve these problems. Firstly, we analyze comprehensively the influences of various dilution atmosphere and fuel type on combustion regimes. The combustion regime classification maps are made out according to the analyses. In succession, we conduct a comparison between the map in air-firing condition and its Oxyfuel counterpart. With the aid of the second thermodynamic-law analysis on the maps, it is easy to identify the major contributors to entropy generation in various combustion regimes in advance, which is crucial for combustion system optimization. Moreover, we find that, for the first time, a combustion regime classification map also may be used as a safety indicator. With the aid of these maps, some conclusions in previous publications can be explained more straightforwardly.
Christian Bergins - One of the best experts on this subject based on the ideXlab platform.
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first test results of Oxyfuel combustion with hitachi s dst burner at vattenfall s 30 mwth pilot plant at schwarze pumpe
Energy Procedia, 2011Co-Authors: Sebastian Rehfeldt, Christian Kuhr, Franz-peter Schiffer, Patrick Weckes, Christian BerginsAbstract:Abstract Situated in the near of Schwarze Pumpe power station southeast of Berlin, Germany, Vattenfall operates a 30 MWth pilot plant in order to investigate the Oxyfuel process. Hitachi Power Europe delivered a DST-burner (DST-Brenner ® ) for the indirect firing system of the plant which was installed without modifications to the pressure part of the boiler. The combustion behavior during Oxyfuel operation was investigated and optimal burner settings for different operation points were established. The results show that the burner can be operated in a wide range of oxygen concentrations in the oxidant gas flow. The burner is characterized by low emissions of carbon monoxide and nitrogen oxides. The high flame stability was found to be unaffected by operational influences such as fluctuations in the coal mass flow, coal quality or soot blowing. Due to the high flame stability the change-over from air blown to Oxyfuel combustion can be realized very easily and is automated. During Oxyfuel operation measurements of temperatures and flue gas species in the flame were performed. The measurement values were compared with the values of the combustion modeling by computational fluid dynamics. The good agreement between both measurement and modeling shows the suitability of the applied models to predict the combustion behavior under Oxyfuel conditions.
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conversion of existing coal fired power plants to Oxyfuel combustion case study with experimental results and cfd simulations
Energy Procedia, 2009Co-Authors: K D Tigges, Friedrich Klauke, K Busekrus, J Niesbach, Martin Ehmann, Christian Kuhr, F Hoffmeister, Bernd Vollmer, Christian Bergins, Thorsten BuddenbergAbstract:Abstract Oxyfuel combustion is one of the promising technologies to enable CCS for new and existing coal-fired power plants. For retrofit applications, Oxyfuel is an attractive option because it does not have major impact on the boiler-turbine steam cycle. This paper presents a case study for retrofitting Oxyfuel combustion technology in large state-of-the-art power plants that are originally commissioned and operated in air-fired mode. The overall process design for the modified power plant is outlined; necessary modifications of relevant components are explained. The paper also discusses results of experiments and numerical calculations on combustion behavior in the furnace. Retrofit measures ensure that the power stations still can run under both air-fired and Oxyfuel-fired conditions if required by regulations/market conditions. This provides additional operational and commercial benefits for the operator of the plant and reduces the technical risk of implementing new components and processes not yet proven in the power sector.
Leema A Almakhadmeh - One of the best experts on this subject based on the ideXlab platform.
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Oxyfuel technology no reduction during oxy oil shale combustion
Fuel, 2014Co-Authors: Leema A Almakhadmeh, J Maier, Günter ScheffknechtAbstract:Abstract Nitrogen oxides are one of the major environmental problems arising from fossil fuels combustion. Oxyfuel combustion is one of the most promising clean coal technologies for pulverized fuel-fired power plants to control and avoid CO 2 emissions; with this technology NO x emissions are significantly reduced. Due to the importance of oil shale utilization in Jordan and all over the world, this study continues with our previous work on oil shale combustion. Unstaged and staged air-firing and Oxyfuel combustion were carried out using Jordanian oil shale collected from El-Lajjun area. The reduction of simulated recycled NO has been investigated in a 20 kW vertical reactor. The actual situation has been simulated by injecting NO in the reactor through the burner. It was found that the simulated recycled NO reduction efficiency is affected by the media and the mode of firing. The simulated recycled NO is reduced efficiently (60–70%) during unstaged Oxyfuel combustion as well as air-firing of El-Lajjun oil shale. The reduction of the injected NO is more efficient with staging compared to unstaged combustion mode for both air-firing and Oxyfuel combustion. The reduction of the injected NO for combustion in air ranges from 61% (without staging) to 100% (with staging) whereas for combustion in 27% O 2 /73% CO 2 , it ranges from 57% (without staging) to 100% (with staging). Moreover, El-Lajjun oil shale ashes are characterized as being high in CaO and SiO 2 , low in Al 2 O 3 , SO 3 , and P 2 O 5 and with minor amounts of F 2 O 3 , MgO, Na 2 O, K 2 O, and TiO 2 .
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Oxyfuel technology no reduction during oxy oil shale combustion
Fuel, 2014Co-Authors: Leema A Almakhadmeh, J Maier, Günter ScheffknechtAbstract:Abstract Nitrogen oxides are one of the major environmental problems arising from fossil fuels combustion. Oxyfuel combustion is one of the most promising clean coal technologies for pulverized fuel-fired power plants to control and avoid CO 2 emissions; with this technology NO x emissions are significantly reduced. Due to the importance of oil shale utilization in Jordan and all over the world, this study continues with our previous work on oil shale combustion. Unstaged and staged air-firing and Oxyfuel combustion were carried out using Jordanian oil shale collected from El-Lajjun area. The reduction of simulated recycled NO has been investigated in a 20 kW vertical reactor. The actual situation has been simulated by injecting NO in the reactor through the burner. It was found that the simulated recycled NO reduction efficiency is affected by the media and the mode of firing. The simulated recycled NO is reduced efficiently (60–70%) during unstaged Oxyfuel combustion as well as air-firing of El-Lajjun oil shale. The reduction of the injected NO is more efficient with staging compared to unstaged combustion mode for both air-firing and Oxyfuel combustion. The reduction of the injected NO for combustion in air ranges from 61% (without staging) to 100% (with staging) whereas for combustion in 27% O 2 /73% CO 2 , it ranges from 57% (without staging) to 100% (with staging). Moreover, El-Lajjun oil shale ashes are characterized as being high in CaO and SiO 2 , low in Al 2 O 3 , SO 3 , and P 2 O 5 and with minor amounts of F 2 O 3 , MgO, Na 2 O, K 2 O, and TiO 2 .
