The Experts below are selected from a list of 147303 Experts worldwide ranked by ideXlab platform
Ahmed F Ghoniem - One of the best experts on this subject based on the ideXlab platform.
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oxy Fuel Combustion of pulverized coal characterization fundamentals stabilization and cfd modeling
Progress in Energy and Combustion Science, 2012Co-Authors: Lei Chen, Sze Zheng Yong, Ahmed F GhoniemAbstract:Oxy-Fuel Combustion has generated significant interest since it was proposed as a carbon capture technology for newly built and retrofitted coal-fired power plants. Research, development and demonstration of oxy-Fuel Combustion technologies has been advancing in recent years; however, there are still fundamental issues and technological challenges that must be addressed before this technology can reach its full potential, especially in the areas of Combustion in oxygen-carbon dioxide environments and potentially at elevated pressures. This paper presents a technical review of oxy-coal Combustion covering the most recent experimental and simulation studies, and numerical models for sub-processes are also used to examine the differences between Combustion in an oxidizing stream diluted by nitrogen and carbon dioxide. The evolution of this technology from its original inception for high temperature processes to its current form for carbon capture is introduced, followed by a discussion of various oxy-Fuel systems proposed for carbon capture. Of all these oxy-Fuel systems, recent research has primarily focused on atmospheric air-like oxy-Fuel Combustion in a CO2-rich environment. Distinct heat and mass transfer, as well as reaction kinetics, have been reported in this environment because of the difference between the physical and chemical properties of CO2 and N2, which in turn changes the flame characteristics. By tracing the physical and chemical processes that coal particles experience during Combustion, the characteristics of oxy-Fuel Combustion are reviewed in the context of heat and mass transfer, Fuel delivery and injection, coal particle heating and moisture evaporation, devolatilization and ignition, char oxidation and gasification, as well as pollutants formation. Operation under elevated pressures has also been proposed for oxy-coal Combustion systems in order to improve the overall energy efficiency. The potential impact of elevated pressures on oxy-Fuel Combustion is discussed when applicable. Narrower flammable regimes and lower laminar burning velocity under oxy-Fuel Combustion conditions may lead to new stability challenges in operating oxy-coal burners. Recent research on stabilization of oxy-Fuel Combustion is reviewed, and some guiding principles for retrofit are summarized. Distinct characteristics in oxy-coal Combustion necessitate modifications of CFD sub-models because the approximations and assumptions for air-Fuel Combustion may no longer be valid. Advances in sub-models for turbulent flow, heat transfer and reactions in oxy-coal Combustion simulations, and the results obtained using CFD are reviewed. Based on the review, research needs in this Combustion technology are suggested.
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operating pressure dependence of the pressurized oxy Fuel Combustion power cycle
Energy, 2010Co-Authors: Jongsup Hong, Marco Gazzino, Randall P Field, Ahmed F GhoniemAbstract:Oxy-Fuel Combustion technology is an attractive option for capturing carbon dioxide (CO2) in power generation systems utilizing hydrocarbon Fuels. However, conventional atmospheric oxy-Fuel Combustion systems require substantial parasitic energy in the compression step within the air separation unit (ASU), the flue gas recirculation system and the carbon dioxide purification and compression unit (CPU). Moreover, a large amount of flue gas latent enthalpy, which has high water concentration, is wasted. Both lower the overall cycle efficiency. Pressurized oxy-Fuel Combustion power cycles have been investigated as alternatives. Our previous study showed the importance of operating pressure for these cycles. In this paper, as the extended work of our previous study, we perform a pressure sensitivity analysis to determine the optimal combustor operating pressure for the pressurized oxy-Fuel Combustion power cycle. We calculate the energy requirements of the ASU and the CPU, which vary in opposite directions as the combustor operating pressure is increased. We also determine the pressure dependence of the water-condensing thermal energy recovery and its relation to the gross power output. The paper presents a detailed study on the variation of the thermal energy recovery rate, the overall compression power demand, the gross power output and the overall net efficiency.
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Techno-Economic Evaluation of Pressurized Oxy-Fuel Combustion Systems
Volume 5: Energy Systems Analysis Thermodynamics and Sustainability; NanoEngineering for Energy; Engineering to Address Climate Change Parts A and B, 2010Co-Authors: Jongsup Hong, Ahmed F Ghoniem, Randall P Field, Marco GazzinoAbstract:Oxy-Fuel Combustion coal-fired power plants can achieve significant reduction in carbon dioxide emissions, but at the cost of lowering their efficiency. Research and development are conducted to reduce the efficiency penalty and to improve their reliability. High-pressure oxy-Fuel Combustion has been shown to improve the overall performance by recuperating more of the Fuel enthalpy into the power cycle. In our previous papers, we demonstrated how pressurized oxy-Fuel Combustion indeed achieves higher net efficiency than that of conventional atmospheric oxy-Fuel power cycles. The system utilizes a cryogenic air separation unit, a carbon dioxide purification/compression unit, and flue gas recirculation system, adding to its cost. In this study, we perform a techno-economic feasibility study of pressurized oxy-Fuel Combustion power systems. A number of reports and papers have been used to develop reliable models which can predict the costs of power plant components, its operation, and carbon dioxide capture specific systems, etc. We evaluate different metrics including capital investments, cost of electricity, and CO2 avoidance costs. Based on our cost analysis, we show that the pressurized oxy-Fuel power system is an effective solution in comparison to other carbon dioxide capture technologies. The higher heat recovery displaces some of the regeneration components of the feedwater system. Moreover, pressurized operating conditions lead to reduction in the size of several other critical components. Sensitivity analysis with respect to important parameters such as coal price and plant capacity is performed. The analysis suggests a guideline to operate pressurized oxy-Fuel Combustion power plants in a more cost-effective way.Copyright © 2010 by ASME
Anker Degn Jensen - One of the best experts on this subject based on the ideXlab platform.
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a model for nitrogen chemistry in oxy Fuel Combustion of pulverized coal
Energy & Fuels, 2011Co-Authors: Hamid Hashemi, Stine Hansen, Maja Bog Toftegaard, Kim Hougaard Pedersen, Anker Degn Jensen, Kim Damjohansen, Peter GlarborgAbstract:In this work, a model for the nitrogen chemistry in the oxy-Fuel Combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gas–solid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal Combustion in O2/CO2 and air, covering the effects of Fuel, mixing conditions, temperature, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-Fuel Combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N2 with CO2. According to the model, differences in the NO yield between the oxy-Fuel Combustion and the conventional Combustion of pulverized coal can mostly be attributed to the recycling of NO (...
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oxy Fuel Combustion of solid Fuels
Progress in Energy and Combustion Science, 2010Co-Authors: Maja Bog Toftegaard, Peter Glarborg, Jacob Brix, Peter Arendt Jensen, Anker Degn JensenAbstract:Abstract Oxy-Fuel Combustion is suggested as one of the possible, promising technologies for capturing CO 2 from power plants. The concept of oxy-Fuel Combustion is removal of nitrogen from the oxidizer to carry out the Combustion process in oxygen and, in most concepts, recycled flue gas to lower the flame temperature. The flue gas produced thus consists primarily of carbon dioxide and water. Much research on the different aspects of an oxy-Fuel power plant has been performed during the last decade. Focus has mainly been on retrofits of existing pulverized-coal-fired power plant units. Green-field plants which provide additional options for improvement of process economics are however likewise investigated. Of particular interest is the change of the Combustion process induced by the exchange of carbon dioxide and water vapor for nitrogen as diluent. This paper reviews the published knowledge on the oxy-Fuel process and focuses particularly on the Combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics. Knowledge is currently available regarding both an entire oxy-Fuel power plant and the Combustion fundamentals. However, several questions remain unanswered and more research and pilot plant testing of heat transfer profiles, emission levels, the optimum oxygen excess and inlet oxygen concentration levels, high and low-temperature fire-side corrosion, ash quality, plant operability, and models to predict NO x and SO 3 formation is required.
Peter Glarborg - One of the best experts on this subject based on the ideXlab platform.
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a model for nitrogen chemistry in oxy Fuel Combustion of pulverized coal
Energy & Fuels, 2011Co-Authors: Hamid Hashemi, Stine Hansen, Maja Bog Toftegaard, Kim Hougaard Pedersen, Anker Degn Jensen, Kim Damjohansen, Peter GlarborgAbstract:In this work, a model for the nitrogen chemistry in the oxy-Fuel Combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gas–solid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal Combustion in O2/CO2 and air, covering the effects of Fuel, mixing conditions, temperature, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-Fuel Combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N2 with CO2. According to the model, differences in the NO yield between the oxy-Fuel Combustion and the conventional Combustion of pulverized coal can mostly be attributed to the recycling of NO (...
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oxy Fuel Combustion of solid Fuels
Progress in Energy and Combustion Science, 2010Co-Authors: Maja Bog Toftegaard, Peter Glarborg, Jacob Brix, Peter Arendt Jensen, Anker Degn JensenAbstract:Abstract Oxy-Fuel Combustion is suggested as one of the possible, promising technologies for capturing CO 2 from power plants. The concept of oxy-Fuel Combustion is removal of nitrogen from the oxidizer to carry out the Combustion process in oxygen and, in most concepts, recycled flue gas to lower the flame temperature. The flue gas produced thus consists primarily of carbon dioxide and water. Much research on the different aspects of an oxy-Fuel power plant has been performed during the last decade. Focus has mainly been on retrofits of existing pulverized-coal-fired power plant units. Green-field plants which provide additional options for improvement of process economics are however likewise investigated. Of particular interest is the change of the Combustion process induced by the exchange of carbon dioxide and water vapor for nitrogen as diluent. This paper reviews the published knowledge on the oxy-Fuel process and focuses particularly on the Combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics. Knowledge is currently available regarding both an entire oxy-Fuel power plant and the Combustion fundamentals. However, several questions remain unanswered and more research and pilot plant testing of heat transfer profiles, emission levels, the optimum oxygen excess and inlet oxygen concentration levels, high and low-temperature fire-side corrosion, ash quality, plant operability, and models to predict NO x and SO 3 formation is required.
Zhaohui Liu - One of the best experts on this subject based on the ideXlab platform.
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Experimental research on the characteristics of ash in oxy-Fuel Combustion
Fuel, 2020Co-Authors: Yi Zhang, Wei Chen, Zhaohui Liu, Tai Zhang, Qing Sun, Zhimin ZhengAbstract:Abstract CO2 capture and storage technology plays an important role in global carbon emission reduction, and oxy-Fuel Combustion is one of the key future technologies. The slagging and deposition characteristics of ash under oxy-Fuel Combustion restrict the competitiveness and development of this technology. In this study, an ash sample of Shenhua coal was obtained in a flat flame-assisted entrained flow reactor under different conditions, and an X-ray diffraction, X-ray fluorescence probe, and scanning electron microscope–energy dispersive spectrometer were used. The slagging tendency under oxy-Fuel Combustion was thoroughly analyzed. Results showed that the characteristics of the ash samples obtained under oxy-Fuel and air Combustion varied. Obvious differences existed in the mineral characteristics and relative content, and these may have affected the slagging characteristics. The presence of Ca in ash was mainly in the form of CaO, and Fe was likely to react with Si, Ca, Al, and other minerals. Compounds with low melting points were generated under oxy-Fuel Combustion, indicating that the slagging tendency was aggravated. Moreover, the slagging tendency of Shenhua coal in different atmospheres was predicted with common and viscosity slagging indexes, and the result was consistent with the experimental ones. The sphericity of the ash samples obtained under oxy-Fuel Combustion was better than that of the samples under air Combustion.
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Dynamic Modeling on the Mode Switching Strategy of a 35 MWth Oxy-Fuel Combustion Pilot Plant
Energy & Fuels, 2019Co-Authors: Zihan Chen, Junjun Guo, Xiang Zhang, Wei Luo, Zhang Tai, Zhaohui LiuAbstract:Large-scale pilot studies of oxy-Fuel Combustion have demonstrated that it is a promising CO2 capture technology. In this study, steady-state and dynamic models of oxy-Fuel Combustion were developed using the Yingcheng 35 MWth oxy-Fuel Combustion pilot facility as a prototype. Using specific features of Aspen software, a customized drum and furnace radiation model was developed to make it easier to represent the real features of the 35 MWth facility. The mode switching process between air Combustion and oxy-Fuel Combustion is focused on in particular, using both a ‘step by step’ and a ‘simultaneous’ switching scheme. It is found that maintaining the gas flow in the oxygen and recirculation flue at different slopes for different switching stages can be an effective switching strategy. ‘Simultaneous’ switching produces a better and smoother dynamic response during the switching process and is more exergy efficient. Together, these results can help to improve the operation of facilities and control system de...
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Opportunities and Challenges of Oxy-Fuel Combustion
Oxy-Fuel Combustion, 2018Co-Authors: Xiaohong Huang, Junjun Guo, Zhaohui Liu, Chuguang ZhengAbstract:This chapter briefly reviews the background, concept, components, R&D history, and opportunities related to the use of oxy-Fuel Combustion and then discusses the theoretical and practical challenges of oxy-Fuel Combustion. An outline for subsequent chapters is also provided.
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Flame Characteristics of Oxy-Fuel Combustion and Burner Design
Oxy-Fuel Combustion, 2018Co-Authors: Junjun Guo, Zhaohui LiuAbstract:Abstract The stability of pulverized coal flames under oxy-Fuel Combustion is one of the most critical issues in engineering practices. After providing a review of the design principles of conventional air Combustion burners, this chapter illustrates the flame features of oxy-Fuel Combustion. The influence of oxy-Fuel Combustion conditions on coal ignition and flame stability are discussed. The design principle and methodology of oxy-coal burners intended for application in utility boilers is proposed, relative to traditional air Combustion burners. For example, we analyze new uses for a 3 MW oxy-coal burner.
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Pilot and Industrial Demonstration of Oxy-Fuel Combustion
Oxy-Fuel Combustion, 2018Co-Authors: Zhaohui Liu, Tai ZhangAbstract:Small and large pilot-scale oxy-Fuel demonstration projects conducted worldwide have provided critical steps toward utilizing this technology on a large scale. No large technical obstacles were found in pilot-scale experiments. Therefore, based on the studies conducted in small pilot facilities, the oxy-Fuel Combustion technology of pulverized coal is now seen as being feasible. The oxy-Fuel Combustion concept was confirmed over the past 5 years by the Schwarze Pumpe, CIUDEN, Callide, and Yingcheng projects. This chapter aims to summarize the information that came out of the small and large oxy-Fuel Combustion pilot projects. The features of the 3 MW full chain system and the Yingcheng 35 MW demonstration system are highlighted.
Maja Bog Toftegaard - One of the best experts on this subject based on the ideXlab platform.
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a model for nitrogen chemistry in oxy Fuel Combustion of pulverized coal
Energy & Fuels, 2011Co-Authors: Hamid Hashemi, Stine Hansen, Maja Bog Toftegaard, Kim Hougaard Pedersen, Anker Degn Jensen, Kim Damjohansen, Peter GlarborgAbstract:In this work, a model for the nitrogen chemistry in the oxy-Fuel Combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gas–solid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal Combustion in O2/CO2 and air, covering the effects of Fuel, mixing conditions, temperature, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-Fuel Combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N2 with CO2. According to the model, differences in the NO yield between the oxy-Fuel Combustion and the conventional Combustion of pulverized coal can mostly be attributed to the recycling of NO (...
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oxy Fuel Combustion of solid Fuels
Progress in Energy and Combustion Science, 2010Co-Authors: Maja Bog Toftegaard, Peter Glarborg, Jacob Brix, Peter Arendt Jensen, Anker Degn JensenAbstract:Abstract Oxy-Fuel Combustion is suggested as one of the possible, promising technologies for capturing CO 2 from power plants. The concept of oxy-Fuel Combustion is removal of nitrogen from the oxidizer to carry out the Combustion process in oxygen and, in most concepts, recycled flue gas to lower the flame temperature. The flue gas produced thus consists primarily of carbon dioxide and water. Much research on the different aspects of an oxy-Fuel power plant has been performed during the last decade. Focus has mainly been on retrofits of existing pulverized-coal-fired power plant units. Green-field plants which provide additional options for improvement of process economics are however likewise investigated. Of particular interest is the change of the Combustion process induced by the exchange of carbon dioxide and water vapor for nitrogen as diluent. This paper reviews the published knowledge on the oxy-Fuel process and focuses particularly on the Combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics. Knowledge is currently available regarding both an entire oxy-Fuel power plant and the Combustion fundamentals. However, several questions remain unanswered and more research and pilot plant testing of heat transfer profiles, emission levels, the optimum oxygen excess and inlet oxygen concentration levels, high and low-temperature fire-side corrosion, ash quality, plant operability, and models to predict NO x and SO 3 formation is required.
