Academic literature on the topic 'Recirculation of flue-gas'
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Journal articles on the topic "Recirculation of flue-gas"
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Vilardi, Giorgio, and Nicola Verdone. "Exergy Analysis of Waste Incineration Plant: Flue Gas Recirculation and Process Optimization." Proceedings 58, no. 1 (November 17, 2020): 29. http://dx.doi.org/10.3390/wef-06923.
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Simulations of two incineration processes, with and without flue gas recirculation, have been carried out performing an exergy analysis to investigate the most critical equipment unit in terms of second-law efficiency. Flue gas from the economizer outlet is employed to partially replace secondary combustion air to reduce, at the same time, incinerator temperature and oxygen concentration. Conversely, in the proposed configuration, the recirculated flue gas flow rate is used to control incinerator temperature, while the air flow rate is used to control the oxygen content of the fumes, leaving the incinerator as close to 6% as possible—i.e., the minimum allowed for existing plants to ensure completion of the combustion reactions and according to environmental regulations—and determines the corresponding minimum flue gas flow rate. The flue gas recirculation guarantees a larger level of energy recovery (up to +3%) and, at the same time, lower investment costs for the lower flow rate of fumes actually emitted if compared to the plant configuration without flue gas recirculation. Various operating parameters were varied (incinerator’s effluent gas temperature, air flowrate and flue gas recirculation flowrate) to investigate their influence on process exergy efficiency. Exergy analysis allowed the individuation of the equipment units characterized by larger exergy destruction and demonstrated that the flue gas recirculation led to an overall process exergy efficiency increase of about 3%.
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Frolov, Yu A., Aggarwal Nokesh, and L. I. Polotskii. "Study of Flue-Gas Recirculation Sintering." Metallurgist 61, no. 7-8 (November 2017): 629–37. http://dx.doi.org/10.1007/s11015-017-0544-3.
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Chmielniak, Tadeusz, Paweł Mońka, and Paweł Pilarz. "Investigation of a combined gas-steam system with flue gas recirculation." Chemical and Process Engineering 37, no. 2 (June 1, 2016): 305–16. http://dx.doi.org/10.1515/cpe-2016-0025.
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Abstract This article presents changes in the operating parameters of a combined gas-steam cycle with a CO2 capture installation and flue gas recirculation. Parametric equations are solved in a purpose-built mathematical model of the system using the Ebsilon Professional code. Recirculated flue gases from the heat recovery boiler outlet, after being cooled and dried, are fed together with primary air into the mixer and then into the gas turbine compressor. This leads to an increase in carbon dioxide concentration in the flue gases fed into the CO2 capture installation from 7.12 to 15.7%. As a consequence, there is a reduction in the demand for heat in the form of steam extracted from the turbine for the amine solution regeneration in the CO2 capture reactor. In addition, the flue gas recirculation involves a rise in the flue gas temperature (by 18 K) at the heat recovery boiler inlet and makes it possible to produce more steam. These changes contribute to an increase in net electricity generation efficiency by 1%. The proposed model and the obtained results of numerical simulations are useful in the analysis of combined gas-steam cycles integrated with carbon dioxide separation from flue gases.
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Han, Juntao, Guofeng Lou, Sizong Zhang, Zhi Wen, Xunliang Liu, and Jiada Liu. "The Effects of Coke Parameters and Circulating Flue Gas Characteristics on NOx Emission during Flue Gas Recirculation Sintering Process." Energies 12, no. 20 (October 10, 2019): 3828. http://dx.doi.org/10.3390/en12203828.
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The new process of flue gas recirculation, which reduces coke consumption and reducing NOx emissions, is now extensively used. Compared with traditional sintering, the characteristics of circulating flue gas and coke parameters significantly affect the combustion atmosphere and coke combustion efficiency. Based on the actual complex process of sintering machine, this study proposes a relatively comprehensive one-dimensional, unsteady mathematical model for flue gas recirculation research. The model encompasses NOx pollutant generation and reduction, as well as SO2 generation and adsorption. We focus on the effects of cyclic flue gas characteristics on the sintering-bed temperature and NOx emissions, which are rarely studied, and provide a theoretical basis for NOx emission reduction. Simulation results show that during sintering, the fuel NOx is reduced by 50% and 10% when passing through the surface of coke particles and CO, respectively. During flue gas recirculation sintering, the increase in circulating gas O2 content, temperature, and supply-gas volume cause increased combustion efficiency of coke, reducing atmosphere, and NOx content in the circulating area; the temperature of the material layer also increases significantly and the sintering endpoint advances. During cyclic sintering, the small coke size and increased coke content increase the char-N release rate while promoting sufficient contact of NOx with the coke surface. Consequently, the NOx reduction rate increases. Compared with the conventional sintering, the designed flue gas recirculation condition saves 3.75% of coke consumption, i.e., for 1.2 kg of solid fuel per ton of sinter, the amount of flue gas treatment is reduced by 21.64% and NOx emissions is reduced by 23.59%. Moreover, without changing the existing sintering equipment, sintering capacity increases by about 5.56%.
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Terada, Shinya, Ryosuke Matsumoto, Isao Ishihara, and Mamoru Ozawa. "D211 DME combustion with flue gas recirculation." Proceedings of the Thermal Engineering Conference 2006 (2006): 319–20. http://dx.doi.org/10.1299/jsmeted.2006.319.
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Stenin, Valery Alexandrovich, and Irina Valer’yevna Ershova. "Improvement of power efficiency and environmental safety of ship boilers." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2020, no. 3 (August 19, 2020): 40–46. http://dx.doi.org/10.24143/2073-1574-2020-3-40-46.
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The article focuses on the methods of reducing nitrogen oxide emissions that are important to consider and apply in operation of ship boilers and thermal power plants, along with other activities aimed to protect the environment. Nitrogen oxide emissions can be restrained by using the technological (primary, in-process) operations. Flue gas recirculation is the most popular method of restraining nitrogen oxide emissions in oil-gas boilers, reducing the temperature and nitrogen oxide concentration in flue gases. Besides affecting the environment, the combustion products recirculation greatly lowers the technical and economic performance of the boiler by decreasing its performance that is why using the method remains limited. There has been described the scheme of flue gas recirculation in the ship auxiliary boilers that ensures reduction of nitrogen oxide emissions and increase in efficiency of boiler furnace. It has been proposed to combine steam and carbon dioxide fuel conversion with power combustion and thermochemical heat regeneration. Thermodynamic feasibility of combustion product recirculation in ship auxiliary boiler has been given. Using the power and stoichiometric analyses of reference liquid fuel combustion, the possibility of fuel conversion has been illustrated for the case when both fuel and recirculation gases are supplied into reburning zone of the furnace. The calculations determine air oxygen ratio for reburning and oxidative zones, flue gas recirculation factor and furnace efficiency change at thermochemical heat regeneration. The study results are proposed to use in non-stoichiometric and staged fuel combustion.
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Barry, Louis T., Richard Gramlich, and Joseph Megale. "FLUE GAS RECIRCULATION IN MULTIPLE HEARTH BIOSOLIDS INCINERATORS." Proceedings of the Water Environment Federation 2002, no. 3 (January 1, 2002): 532–47. http://dx.doi.org/10.2175/193864702785302203.
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Fan, X., Z. Yu, M. Gan, X. Chen, and Y. Huang. "Flue gas recirculation in iron ore sintering process." Ironmaking & Steelmaking 43, no. 6 (June 7, 2016): 403–10. http://dx.doi.org/10.1179/1743281215y.0000000029.
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Alexanda Petrovic, Ben, and Salman Masoudi Soltani. "Optimization of Post Combustion CO2 Capture from a Combined-Cycle Gas Turbine Power Plant via Taguchi Design of Experiment." Processes 7, no. 6 (June 12, 2019): 364. http://dx.doi.org/10.3390/pr7060364.
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The potential of carbon capture and storage to provide a low carbon fossil-fueled power generation sector that complements the continuously growing renewable sector is becoming ever more apparent. An optimization of a post combustion capture unit employing the solvent monoethanolamine (MEA) was carried out using a Taguchi design of experiment to mitigate the parasitic energy demands of the system. An equilibrium-based approach was employed in Aspen Plus to simulate 90% capture of the CO2 emitted from a 600 MW natural gas combined-cycle gas turbine power plant. The effects of varying the inlet flue gas temperature, absorber column operating pressure, amount of exhaust gas recycle, and amine concentration were evaluated using signal to noise ratios and analysis of variance. The optimum levels that minimized the specific energy requirements were a: flue gas temperature = 50 °C; absorber pressure = 1 bar; exhaust gas recirculation = 20% and; amine concentration = 35 wt%, with a relative importance of: amine concentration > absorber column pressure > exhaust gas recirculation > flue gas temperature. This configuration gave a total capture unit energy requirement of 5.05 GJ/tonneCO2, with an energy requirement in the reboiler of 3.94 GJ/tonneCO2. All the studied factors except the flue gas temperature, demonstrated a statistically significant association to the response.
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Gao, Jian Qiang, Ning Wang, Yu Lan Wang, and Liang Jie Shen. "Pulverizing System Simulation Model of a 300MW Oxy-Fuel Coal Fired Boiler." Advanced Materials Research 997 (August 2014): 670–73. http://dx.doi.org/10.4028/www.scientific.net/amr.997.670.
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This paper focused on researching the pulverizing system of a 300MW oxy-fuel coal fired boiler, which took dehydrated recirculation flue gas as the drying medium. According to the working principle, the paper established the simulation model, and completed dynamic simulation tests basing on the IMMS platform. The dynamic simulation tests included the disturbances of the pressure of the flue gas inlet and the opening degree of the main flue gas valve. The results demonstrate that the model is precise, stable and it possesses good dynamic characteristic.
Dissertations / Theses on the topic "Recirculation of flue-gas"
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Anuar, Shahrani Haji. "Environmental performance of air staged combuster with flue gas recirculation to burn coal/biomass /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848891512393.
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Stimpson, Curtis K. "The Composition and Morphology of Coal Ash Deposits Collected in an Oxy-Fuel, Pulverized Coal Reactor." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3225.
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Coal ash deposits were collected in a 160 kWth, down-fired oxy-coal reactor under staged and unstaged conditions for four different coals (PRB, Gatling, Illinois #6, and Mahoning). Concentration measurements of carbon, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, chromium, manganese, iron, nickel, strontium, and barium were gathered from each deposit sample using scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Backscattered electron micrographs for each deposit sample were analyzed to gather morphological data. Particle size and shape were studied for each deposit collected. The average particle sizes of the particles in upstream deposits were much larger than the average particle sizes of the downstream deposits. The downstream deposits consisted primarily of spherical particles while the upstream deposits consisted of round, irregular polygonal, and porous particles. Deposit particles are believed to have deposited at all stages of burnout; those depositing early during pyrolysis may have continued to react after deposition. Element maps for the aforementioned elements were collected with SEM-EDS and analyzed to quantify both average composition and composition of individual particles. These values were compared to ASTM ash analyses performed for each coal and ash collected from the flue gas stream with a cyclonic particle separator. It was found that sulfur concentrations of deposits do not correlate with corresponding sulfur concentrations of the coal. Comparison of similar experiments performed with air-combustion show that oxy-combustion deposits contain about twice as much sulfur as air-combustion deposits when burning the same coal. Deposition propensity of each coal was also examined, and the PRB and Gatling coals were found to have a moderately high deposition propensity whereas the deposition propensity of the Mahoning and Illinois #6 coals was fairly low.
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Pawlitko, David. "Návrh mlýnice s kroužkovými mlýny s recirkulací spalin a bez recirkulace spalin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232168.
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This master’s thesis deals with the issue of recirculating of flue-gas of pulverized coal-fired boiler. Part of the thesis are thermal calculations of mills for operational status with and without flue-gas recirculation and design of routes of recirculated flue-gas into the mills at the level of feasibility study.
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Macenauerová, Tereza. "Vliv vnitřní recirkulace spalin na charakteristické parametry spalování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232140.
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This thesis deals with the evaluation of emissions of NOx and CO formed during the combustion process when the burner utilizing fuel staging and internal flue gas recirculation is used. In the theoretical part the NOx formation mechanisms and methods used to suppress their formation are described. This is followed with the currently valid legislation in the Czech Republic in terms of the emission limits for NOx and CO in stationary sources. In the work, combustion tests were performed at the burners testing facility at UPEI BUT. The tests revealed that the most important parameters, which influence the NOx formation, are fuel staging, increasing combustion air excess and the utilization of new equipment that induces the flue gas to be drawn back into the burner. The equipment is installed in the burner’s air channel. The dependence of flue gas temperature, heat flux to the combustion chamber’s section walls and in-flame temperatures distribution in the horizontal symmetry plane of the combustion chamber on various parameters were investigated. The parameters included the geometry of the equipment for flue gas recirculation, primary/secondary ratio, geometry of nozzles for secondary fuel supply, tangential orientation of these nozzles towards the burner axis, and the excess of combustion air.
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Zheng, Ya. "Etude d'un écoulement réactif turbulent stabilisé par un dièdre dans un canal bidimensionnel." Poitiers, 1988. http://www.theses.fr/1988POIT2325.
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Etude theorique de la situation d'ecoulements reactifs dans un canal bidimensionnel stabilises par un obstacle de section triangulaire au niveau du plan median du canal. Les resultats de calculs concernent des ecoulements non reactifs d'une part et des ecoulements reactifs a faible taux d'expansion thermique
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Müller, Jan. "Kondenzační technika a odvody spalin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226844.
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This thesis is developed as a proposal for heating for a primary school and kindergarten in the region of Brno-countryside. For the insulated building, a combination of heating and air-conditioning is proposed. The concept is designed so that the air-conditioning preheats the exterior air and the heating system warms the incoming air to a comfortable temperature. For the required thermal performance, sources of heat (for gas and pellets) and a layout solution for the boiler room is designed. Drainage of combustion products is proposed for both solutions. The project solution is per the extent of the construction permit. The theoretical part is linked with the practical part through the condensation boilers, their function and division, and drainage of combustion products. The experiment for the given topic was conducted on the drainage of combustion products. The pressure loss of the reverse knob was determined in relation to the flow rate of air in the condensation boilers as this loss is essential in assessing the drainage of combustion products.
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Tsai, Ching-Chao, and 蔡景昭. "Formation of NO in staged-air combustion with flue gas recirculation." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/13856964859023225127.
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碩士國立臺灣大學
機械工程研究所
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The purpose of this research is to study the control of NOx formation and destruction by using air-staged combustion tech- nology with natural gas fuel. The experiments include changing the strength of swirl in primary combustion zone ( PCZ ), lowing the local combustion temperature, and adjusting flue gas re- circulation ( FGR ) amount to optimize the reduction of NOx emission in a small-scale 70,000 Btu/hr furnace. The available experimental results are used to identify the best operating condition for controling NOx emission. The exhausting amount of NO is mainly dependent upon the fuel-air mixing in the PCZ by using air-staged combustion. The moderate adjusting the staged air and the strength of swirl can efficiency are found in L/ D=5.2 region when in the case .PHI.= 1.00 and S=0.56. It is also found that the adding of 17% FGR into PCZ may improve the NO-reduction. However, while increasing the amount of FGR over 17%, the NO-emission will not be improved and the flame is in instable condition.
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Hu, Chun-Hsuan, and 胡駿軒. "Combustion of Sawdust in a Vortexing Fluidized Bed Combustor with Flue Gas Recirculation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51008207342506854315.
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碩士中原大學
化學工程研究所
100
Sawdust is an easily available bio-fuel, it usually has high concentration of CO emission when using in a fluidized bed combustor. In this study, combustion of sawdust was investigated in a vortexing fluidized bed combustor with flue gas recirculation. The second air was introduced into the freeboard tangentially to enhance the residence time of fine fuel particle in the combustor. Bed temperature, excess air ratio, stoichiometric oxygen ratio in the bed and particle size were studied to compare the difference of combustion proportion, axial distribution and pollutant emissions. The results showed that the combustion proportion had less effect by bed temperature, stoichiometric oxygen ratio in the bed share impact for splashing zone and secondary air injection region significantly. Besides, the larger particle size, the higher the combustion proportion in the bed. CO emission decreased as bed temperature, excess oxygen ratio, stoichiometric oxygen ratio in the bed and particle size increased. The particle size had the greatest impact for CO emission. The CO emission decreased from 1759 to 849 ppm when the particle size of sawdust from maximum to minimum. The lowest CO concentration 11 ppm was obtained while RDF employed. The effect of operation conditions on NOX emission is minimum, and NOX emission is below regulation. Therefore, sawdust is a clean bio-fuel. Generally speaking, the optimum operating conditions is at 750℃, with 70% excess oxygen ratio and 100% stoichiometric oxygen ratio in the bed. Although the CO emission is too high, the change of operating conditions suitability or prepared it to RDF fuel. It still has much potential using in FBC.
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Lin, chien-Wei, and 林建瑋. "Combustion of Rice Husk in a Vortexing Fluidized Bed Combustor with Flue Gas Recirculation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/83248595275226621008.
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碩士中原大學
化學工程研究所
100
Rice husk is a large amount of biomass energy, because of its high yield and bulk density, so that it’s a problem for disposal, it can be a fuel for converting to useful energy. In this study, combustion of rice husk was investigated in a vortexing fluidized bed combustor. Use silica sand as bed material. The combustor has a 4.6m height, 0.8m × 0.4m of combustion chamber and a 0.75 inner diameter of freeboard. The second air was inducted into the freeboard tangentially at 2.05m height above the air distributor. A vortexing fluidized bed combustor, was tested for combustion characteristics of rice-husk, feed rate maintain 40kg/hr, total primary air is 3Nm3/min, secondary air is 2Nm3/min; different operating conditions (excess oxygen ratio, air ratio, stoichiometric oxygen percentage in the bed) at flue gas recirculation operating (FGR) was utilized to discuss the axial temperature distribution, CO and NOx emissions, combustion efficiency and combustion proportion, then compare to direct combustion and stage combustion which doesn’t use FGR . The experimental results showed that the optimum operating condition is FGR, which can lower CO and NOx emissions to 61ppm and 86ppm individualy, and combustion efficiency is about 95%~99%; if taking combustion efficiency and pollutant emissions into consideration, 50% excess oxygen ratio and 100% stoichiometric oxygen percentage in the bed is the optimum operating. As stoichiometric oxygen percentage increase, the combustion proportion of bed region increase ; excess oxygen ratio increase, because the excess oxygen inject into secondary air, which provide good combustion atmosphere, causing the increasement of combustion proportion in freeboard .
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Wang, Yuan-Jie, and 王源杰. "Combustion of Peanut Shell in a Vortexing Fluidized Bed Combustor with Flue Gas Recirculation." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/26426894465545238676.
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碩士中原大學
化學工程研究所
101
Peanut shell is common agricultural waste in Taiwan, and its high calorific value is suitable to be used as biomass fuel for fluidized bed combustion. In this study, the experiments are conducted in a vortexing fluidized bed combustor (VFBC) using silica sand as bed materials. The combustor has a height of 4.6 m. The combustion chamber is 0.8 m × 0.4 m in area and freeboard has an ID of 0.75 m. The secondary gas is introduced into the freeboard tangentially at 2.05 m above the air distributor plate. Different operating conditions, including excess oxygen ratio, stoichiometric oxygen ratio in the bed, and particle sizes, are used to investigate their effects on the axial temperature profile, pollutant emissions, combustion efficiency, and combustion fractions. Furthermore, in order to understand the vortexing effect, with a fixed total oxygen rate of 0.8175 Nm3/min and primary gas rate of 3 Nm3/min in the furnace, nitrogen is added to secondary gas in 4 separate runs with the rate of (0, 0.44, 0.75 and 1 Nm3/min), respectively. The results showed that crushed peanut shell can cause bridging in the hopper during the feeding process; therefore, compressed shell pellets is the best way to solve the feeding problem. As excess oxygen ratio increases, both of crushed and pelletized peanut shell have higher bed temperature and combustion efficiency. As stoichiometric oxygen ratio increases, different results for crushed and pelletized peanut shell are observed. This is due to the different major combustion locations from different particle densities of the two fuels. Axial CO and NOx profiles indicate there are two specific regions inside the reactor, i.e. formation and decomposition. The CO emission from the vortexing FBC is found to be in the range of 55-73 ppm for crushed peanut shell and of 45-60 ppm for pelletized peanut shell, with excess oxygen ratio of 40-60%. In every experiment, combustion efficiency of peanut shell is always over 99%.
Book chapters on the topic "Recirculation of flue-gas"
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Matsumoto, Ryosuke, Mamoru Ozawa, Shinya Terada, and Takenori Iio. "Low NO x Combustion of DME by Means of Flue Gas Recirculation." In Challenges of Power Engineering and Environment, 1247–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-76694-0_233.
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Wiswall, James T., Mark Kruzynski, and Srinivas Garimella. "An Experimental Investigation of a Flue Gas Recirculation System for Aluminum Melting Furnaces." In Energy Technology 2014, 165–74. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118888735.ch21.
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Li, Gao-liang, Fang Niu, Yan-yan Gong, and Nai-ji Wang. "Research on Flue Gas Recirculation Coupled Air Staging in an Industrial Pulverized Coal Boiler." In Clean Coal Technology and Sustainable Development, 221–27. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2023-0_29.
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Sidorkin, Vladimir, and Andrey Tugov. "Flue Gas Recirculation Impact on NO x Formation in TP-101-Type Boiler at Estonian Power Plant." In Clean Coal Technology and Sustainable Development, 387–91. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2023-0_52.
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Croiset, E., and K. V. Thambimuthu. "Coal combustion with flue gas recirculation for CO2 recovery." In Greenhouse Gas Control Technologies 4, 581–86. Elsevier, 1999. http://dx.doi.org/10.1016/b978-008043018-8/50093-x.
Full textConference papers on the topic "Recirculation of flue-gas"
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Chudnovsky, Yaroslav, Serguei Zelepouga, Alexei Saveliev, John Wagner, and Vitaly Gnatenko. "NOx Reduction in Partially Premixed Flames by Flue Gas Recirculation." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-39367.
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The authors are currently investigating new technical (both design and operation) approach, which is expected to enable the improvement of the performance of partially premixed type burners without jeopardizing the simplicity, cost, and reliability that this type of burners are well known for. The improvements include significant reduction of the NOx emission without substantial redesign of the combustion system. The results of the experimental investigation of burner operation and design improvements are to be presented and further discussed at the podium.
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Guethe, Felix, Marta de la Cruz Garci´a, and Andre´ Burdet. "Flue Gas Recirculation in Gas Turbine: Investigation of Combustion Reactivity and NOX Emission." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59221.
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Flue gas recirculation (FGR) is a promising technology for the optimization of post-combustion CO2 capture in natural gas combined cycle (NGCC) plants. In this work, the impact of FGR on lean gas turbine premix combustion is predicted by analytical and numerical investigations as well as comparison to experiments. In particular the impact of vitiated air condition and moderate increase of CO2 concentration into combustion reactivity and NOx emission is studied. The influence of inlet pressure, temperature and recirculated NOx are taken as parameters of this study. Two different kinetic schemes are used to predict the impact that FGR has on the combustion process: the GRI3.0 and the RDO6_NO, which is a newly compiled mechanism from the DLR Stuttgart. The effects of the FGR on the NOx emissions are predicted using a chemical reactor network including unmixedness as presumed probability density function (PDF) to account for real effects. The magnitude and ratio of prompt to post-flame thermal NOx changes with the FGR-ratio producing less post flame NOx at reduced O2 content. For technical mixtures (i. e. an industrial fuel injector), NOx emission can be expected to be lower with the vitiation of the oxidizer. This is due to several effects: at low O2 concentration, the highest possible adiabatic flame temperatures for stoichiometric conditions decreases resulting in lower NOx when averaged over all mixing fractions. Further effects result from lower post flame NOx production and the role of “reburn” chemistry, actually reducing NOx (recirculated from the exhaust), which might become relevant for the high recirculation ratios, where parts of the flame would operate at rich stoichiometry at given unmixedness. Therefore in general for each combustor technical mixing could decrease NOx with respect to perfect mixing at high FGR-ratio assuming the engine can still be operated. Although the findings are quite general for gas turbines the advantage that reheat engines have in terms of operation are highlighted. For reheat engines this can be understood as an extension of the “reheat concept” and used as the next step in the goal to achieve minimal emissions at increasing power. In addition, NOx emission obtained in FGR combustion reduces even further when the engine pressure ratio increases, making the concept particularly well suited for reheat engines.
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Burdet, Andre´, Thierry Lachaux, Marta de la Cruz Garci´a, and Dieter Winkler. "Combustion Under Flue Gas Recirculation Conditions in a Gas Turbine Lean Premix Burner." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23396.
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An EV burner as installed in Alstom’s dry low NOx gas turbines was experimentally investigated under different Flue Gas Recirculation (FGR) and engine conditions. FGR enables the reduction of the high exhaust volume flow while significantly increasing the exhaust CO2 concentration. This may substantially improve the post-combustion capture of CO2. However, FGR introduces consequent changes in the gas turbine combustion process mainly because of the oxygen depletion and CO2 increase within the oxidizer. N2 and CO2 were mixed with air in order to obtain at the burner inlet a synthetic oxidizer mixture reproducing O2 and CO2 levels spanning different FGR levels of interest for engine operation. In addition, various degrees of unmixedness of the reactive mixture were investigated by varying the ratio of fuel injected at different port locations in the investigated burner set. Stable operation was achieved in all tested conditions. The lean premix flame shifts downstream when O2 is depleted due to the decrease of the reactivity, although it always stays well within the combustion chamber. The potential for NOx reduction when using FGR is demonstrated. Changes of the NOx formation mechanism are described and compared to the experimental data for validation. Unmixedness appears to be less detrimental to NOx emission when under high FGR ratio. However, CO emission is shown to increase when FGR ratio is increased. Meanwhile, with the present gas turbine combustor, the CO emission follows the equilibrium limit even at high FGR ratio. Interestingly, it is observed that when the burner inlet pressure is increased (and consequently the inlet burner temperature), the increase of CO emission due to FGR is lowered while the NOx emission stays at a very low level. This present an argument for using a higher cycle pressure in gas turbines optimized for FGR operation.
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Sander, Frank, Richard Carroni, Stefan Rofka, and Eribert Benz. "Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45608.
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The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.
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Fischer, Stefan, David Kluß, and Franz Joos. "Experimental Investigation of a Fuel Flexible Generic Gas Turbine Combustor With External Flue Gas Recirculation." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25388.
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Flue gas recirculation in combined cycle power plants using hydrocarbon fuels is a promising technology for increasing the efficiency of the post combustion carbon capture and storage process. However, the operation with flue gas recirculation significantly changes the combustion behavior within the gas turbine. In this paper the effects of external flue gas recirculation on the combustion behavior of a generic gas turbine combustor was experimentally investigated. While prior studies have been performed with natural gas, the focus of this paper lies on the investigation of the combustion behavior of alternative fuel gases at atmospheric conditions, namely typical biogas mixtures and syngas. The flue gas recirculation ratio and the fuel mass flow were varied to establish the operating region of stable flammability. In addition to the experimental investigations, a numerical study of the combustive reactivity under flue gas recirculation conditions was performed. Finally, a prediction of blowout limits was performed using a perfectly stirred reactor approach and the experimental natural gas lean extinction data as a reference. The extinction limits under normal (non-vitiated) and flue gas recirculation conditions can be predicted well for all the fuels investigated.
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Guethe, Felix, Dragan Stankovic, Franklin Genin, Khawar Syed, and Dieter Winkler. "Flue Gas Recirculation of the Alstom Sequential Gas Turbine Combustor Tested at High Pressure." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45379.
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Concerning the efforts in reducing the impact of fossil fuel combustion on climate change for power production utilizing gas turbine engines Flue Gas Recirculation (FGR) in combination with post combustion carbon capture and storage (CCS) is one promising approach. In this technique part of the flue gas is recirculated and introduced back into the compressor inlet reducing the flue gas flow (to the CCS) and increasing CO2 concentrations. Therefore FGR has a direct impact on the efficiency and size of the CO2 capture plant, with significant impact on the total cost. However, operating a GT under depleted O2 and increased CO2 conditions extends the range of normal combustor experience into a new regime. High pressure combustion tests were performed on a full scale single burner reheat combustor high-pressure test rig. The impact of FGR on NOx and CO emissions is analyzed and discussed in this paper. While NOx emissions are reduced by FGR, CO emissions increase due to decreasing O2 content although the SEV reheat combustor could be operated without problem over a wide range of operating conditions and FGR. A mechanism uncommon for GTs is identified whereby CO emissions increase at very high FGR ratios as stoichiometric conditions are approached. The feasibility to operate Alstom’s reheat engine (GT24/GT26) under FGR conditions up to high FGR ratios is demonstrated. FGR can be seen as continuation of the sequential combustion system which already uses a combustor operating in vitiated air conditions. Particularly promising is the increased flexibility of the sequential combustion system allowing to address the limiting factors for FGR operation (stability and CO emissions) through separated combustion chambers.
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Winkler, Dieter, Simon Reimer, Pascal Mu¨ller, and Timothy Griffin. "Comparison of Methane and Natural Gas Combustion Behavior at Gas Turbine Conditions With Flue Gas Recirculation." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22571.
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The efficiency and economics of carbon dioxide capture in gas turbine combined cycle power plants can be significantly improved by introducing Flue Gas Recirculation (FGR) to increase the CO2 concentration in the flue gas and reduce the volume of the flue gas treated in the CO2 capture plant [1], [2]. The maximum possible level of FGR is limited to that corresponding to stoichiometric conditions in the combustor. Reduced excess oxygen, however, leads to negative effects on overall fuel reactivity and thus increased CO emissions. Combustion tests have been carried out in a generic burner under typical gas turbine conditions with methane, synthetic natural gas (mixtures of methane and ethane) and natural gas from the Swiss net to investigate the effect of different C2+ contents in the fuel on CO burnout. To locate the flame front and to measure emissions for different residence times a traversable gas probe was designed and employed. Increasing the FGR ratio led to lower reactivity indicated by a movement of the flame front downstream. Thus, sufficient flame burnout—indicated by low emissions of unburned components (CO, UHC)—required a longer residence time in the combustion chamber. Adding C2+ or H2 to the fuel moved the flame zone back upstream and reduced the burnout time. Tests were performed for the various fuel compositions at different FGR ratios and oxidant preheat temperatures. For all conditions the addition of ethane (6 and 16% vol.) or hydrogen (20% vol.) to methane shows comparable trends. Addition of hydrogen to (synthetic) natural gas which already contains C2+ has less of a beneficial effect on reactivity and CO burnout than the addition of hydrogen to pure methane. A simple ideal reactor network based on plug flow reactors with internal hot gas recirculation was used to model combustion in the generic combustor. The purpose of such a simple model is to generate a design basis for future tests with varying operating conditions. The model was able to reproduce the trends found in the experimental investigation, for example the level of H2 required to offset the effect of oxygen depletion due to simulated FGR.
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Camporeale, S. M., F. Casalini, and A. Saponaro. "Mild Combustion in a Novel CCGT Cycle With Partial Flue Gas Recirculation." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38743.
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A novel Combined Cycle Gas Turbine layout is proposed for using heavy fuel oil in a combustion mode called “Mild Combustion”, characterized by a very low adiabatic flame temperature and flat temperature field in the combustion chamber and low pollutant emissions. “Mild Combustion” is obtained by means of the dilution of reactants with inert gas like combustion product resulting in a very low oxygen concentration of the mixture at the ignition. To stabilize the combustion process in such a condition the reactants temperature has to be raised above the self ignition value. In industrial application this particular preconditioning of the reactants can be reached partially before the combustion chamber and finally in process by means of a performed aerodynamic that further dilute and heat-up the mixture. An experimental analysis of the oil combustion behaviour inside the gas turbine exhaust flow has been arranged at Centro Combustione of Ansaldo Caldaie in Gioia del Colle (Italy). The turbine exhaust gases are simulated by mixing those produced in a gas burner with external air preheated at different temperatures in order to have different final oxygen concentrations and temperature levels. The influence of the main combustion parameters regarding the process feasibility and environmental impact are presented and analysed. Good results in terms of NOx emissions and soot formation have been obtained for heavy oil combustion in a 10% oxygen oxidizer concentration requiring a combustion chamber inlet temperature of about 900K. In order to meet these conditions, a novel CCGT cycle in which about 64% of combustion products are re-circulated before entering the combustion chamber, is proposed. The thermodynamic analysis shows that the efficiency that could be achieved by the proposed cycle is a few percent lower than the efficiency of a combined cycle power plant fuelling natural gas, with the same turbine inlet temperature and similar turbine blade cooling technology.
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Qubbaj, Ala R. "Flue-Gas Versus Fuel-Injection Recirculation: Effects on Structure and Pollutant Emissions." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82098.
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In this study, a co-flow methane/air diffusion flame at Reynolds number of 6000 was numerically simulated. The co-flow air and fuel streams were diluted with Nitrogen in the range of 0% to 20%. The thermal and composition fields in the far-burner reaction zone (close to the exhaust) were computed, and the effects of diluent’s addition to the air stream (simulating FGR) and to the fuel stream (simulating FIR) were investigated. The results show that air-side dilution is very effective up to 5% diluent’s addition. For which, 95% and 65% drops in NO and CO emissions, respectively, along with a 16% increase in temperature, are predicted compared to the baseline case (0% dilution). However, beyond 5% dilution, no effect (reaction) has been predicted. On the other hand, the fuel-side dilution has shown an effect for all simulated diluent’s addition (i.e. 0%–20%). However, that effect is not systematic neither on temperature, CO or NO concentrations. For a similar 5% dilution to the fuel-side, a 14% increase in NO and a 97% decrease in CO are predicted, along with a 5.6% increase in temperature. The simulated results revealed that air-side dilution (simulating FGR) has a dramatic greater effectiveness in NO reduction, whereas, fuel-side dilution (simulating FIR) has a greater effectiveness in CO reduction. Besides, the results suggest an important role for Prompt-NO Fenimore mechanism.
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Winkler, Dieter, Pascal Mu¨ller, Simon Reimer, Timothy Griffin, Andre´ Burdet, John Mantzaras, and Yohannes Ghermay. "Improvement of Gas Turbine Combustion Reactivity Under Flue Gas Recirculation Condition With In-Situ Hydrogen Addition." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59182.
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Carbon Capture and Storage (CCS) solutions are currently being assessed in order to address appropriately the climate change challenge. Post-combustion CO2 capture is one of the technologies proposed for both coal-fired and gas-fired power plants. In Natural Gas Combined Cycle (NGCC), the flue gas is treated after the Heat Recovery Steam Generator (HRSG) in a so-called post-combustion CO2 capture module through use of solvents. The size of systems envisaged for the capture of CO2 scales with volumetric flow to be treated together with the CO2 concentration contained in the flue gas. Flue Gas Recirculation (FGR) is proposed as a means to increase CO2 concentration in the flue gas together with a net reduction of volumetric flow to be treated by the CO2 capture module. One of the limiting factors of this technology is the vitiation of air within gas turbine combustor and the associated reduction in oxygen concentration. This paper analyses the influence of air vitiation upon combustion in a generic premix lean industrial burner. Tests are carried out under representative inlet pressure and temperature levels. Variation of inlet oxidizer composition is simulated with the addition of nitrogen and carbon dioxide to the inlet air. It is observed that CO emission increases with oxygen depletion at a fixed residence time, signaling a reduction of combustion reactivity. In addition, NOx emission is shown to be sensitive to oxygen depletion. In order to mitigate reduction of combustion reactivity, hydrogen is added to the fuel, up to 20% in volume. As another alternative, a Catalytic Partial Oxidation (CPO) reactor is used in-situ in order to reform the fuel to different syngas blends. These syngas is then used as fuel, which enables the enhancement of the combustion reactivity counter-acting the impact of FGR conditions. The hydrogen addition appears to help improving the reactivity of the flame, making this concept relevant for operation under vitiated air condition.
Reports on the topic "Recirculation of flue-gas"
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Rue, David. Next Generation Pressurized Oxy-Coal Combustion: High Efficiency and No Flue Gas Recirculation. Office of Scientific and Technical Information (OSTI), September 2013. http://dx.doi.org/10.2172/1165572.
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Doctor, R. D., J. C. Molburg, N. F. Brockmeier, and M. Mendelsohn. CO{sub 2} capture for PC boilers using flue-gas recirculation : evaluation of CO{sub 2} recovery, transport, and utilization. Office of Scientific and Technical Information (OSTI), March 2002. http://dx.doi.org/10.2172/793089.
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