Academic literature on the topic 'Coal-fired furnaces – Mathematical models'
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Journal articles on the topic "Coal-fired furnaces – Mathematical models"
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Askarova A.S., Bolegenova S.A., Safarik P., Bolegenova S.A., Maximov V.Yu, Beketayeva M.T., and Nugymanova A.O. "MODERN COMPUTING EXPERIMENTS ON PULVERIZED COAL COMBUSTION PROCESSES IN BOILER FURNACES." PHYSICO-MATHEMATICAL SERIES, no. 6 (December 15, 2018): 5–14. http://dx.doi.org/10.32014/2018.2518-1726.11.
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The aim of the work is to create new computer technologies for 3D modeling of heat and mass transfer processes in high-temperature physico-chemical-reactive environments that will allow to determine the aerodynamics of the flow, heat and mass transfer characteristics of technological processes occurring in the combustion chambers in the operating coal TPP RK. The novelty of the research lies in the use of the latest information technologies of 3D modeling, which will allow project participants to obtain new data on the complex processes of heat and mass transfer during the burning of pulverized coal in real combustion chambers operating in the CHP of RK. Numerical simulation, including thermodynamic, kinetic and three-dimensional computer simulation of heat and mass transfer processes when burning low-grade fuel, will allow finding optimal conditions for setting adequate physical, mathematical and chemical models of the technological process of combustion, as well as conduct a comprehensive study and thereby develop ways to optimize the process of ignition, gasification and burning high ash coals. The proposed methods of computer simulation are new and technically feasible when burning all types of coal used in pulverized coal-fired power plants around the world. The developed technologies will allow replacing or eliminating the conduct of expensive and labor-consuming natural experiments on coal-fired power plants.
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Wan, Wen Jun, Zhi Yuan Fan, Wei Jian Huang, and Shi He Chen. "Dynamic Characteristics and Mathematical Models of Filled Level for Ball Mills with Double Inlets and Outlets." Advanced Materials Research 1008-1009 (August 2014): 988–94. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.988.
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Ball mills with double inlets and outlets (BMDIO) are widely equipped in milling systems of thermal power plants because of BMDIOs’ vantage on being able to pulverize various raw coal. In this paper, dynamic characteristics of mill’s coal level were studied by pulverizing coal mechanism analysis. Furthermore, models for filled level of mill were obtained with mathematical Equations. The nonlinear, strong coupling and large lag features of BMDIO’s dynamic characteristics were demonstrated by the model for level of materiel constructed in this paper. And, the model would be become the available theory basis for the calculation of pulverized coal into furnace and design of combustion in fossil-fired thermal unit.
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Crnomarkovic, Nenad, Miroslav Sijercic, Srdjan Belosevic, Dragan Tucakovic, and Titoslav Zivanovic. "Influence of application of Hottel’s zonal model and six-flux model of thermal radiation on numerical simulations results of pulverized coal fired furnace." Thermal Science 16, no. 1 (2012): 271–82. http://dx.doi.org/10.2298/tsci110627126c.
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Difference of results of numerical simulation of pulverized coal fired furnace when mathematical models contain various radiation models has been described in paper. Two sets of numerical simulations of pulverized coal fired furnace of 210 MWe power boiler have been performed. One numerical simulation has contained Hottel?s zonal model, whereas the other numerical simulation has contained six-flux model. Other details of numerical simulations have been identical. The influence of radiation models has been examined through comparison of selected variables (gas-phase temperature, oxygen concentration, and absorbed radiative heat rate of surface zones of rear and right furnace walls), selected global parameters of furnace operation (total absorbed heat rate by all furnace walls and furnace exit gas-phase temperature). Computation time has been compared as well. Spatially distributed variables have been compared through maximal local differences and mean differences. Maximal local difference of gas-phase temperature has been 8.44%. Maximal local difference of absorbed radiative heat rate of the surface zones has been almost 80.0%. Difference of global parameters of furnace operation has been expressed in percents of value obtained by mathematical model containing Hottel?s zonal model and has not been bigger than 7.0%. Computation time for calculation of 1000 iterations has been approximately the same. Comparison with other radiation models is necessary for assessment of differences.
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Wen, Xiao Qiang. "Comparison and Application of Two Mathematical Models in Predicting and Determining the State of Deposition and Slagging of Coal Burning Boiler." Advanced Materials Research 818 (September 2013): 240–45. http://dx.doi.org/10.4028/www.scientific.net/amr.818.240.
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Building a model to predict the state of slag on coal-fired boilers is a good way to optimize the coal combustion and reduce the risk of boiler slag. This paper built new models based on vague sets to predict the state of slag on coal-fired boilers, in which there were six input vectors, which were softening temperature, SiO2-Al2O3 ratio, alkali-acid ratio, percentage of silicon content, the dimensionless average temperature furnace and the dimensionless inscribed circle diameter furnace, and one output vectors, which was slagging degree. Two methods, which were based on the sense of distance and symmetric fuzzy cross entropy, were proposed to calculate the similarity between vague sets. 10 coal burning boilers were selected as known samples and the feasibility of the new methods was proved by the result of predicting the state of slag on the four coal burning boilers from Jilin heat and power plant, Xinli power plant, Jinzhou power plant and Qinhuangdao power plant. Through predicting and determining, it proves that the two pattern recognition models are high in prediction accuracy. Compared with the normal method, it is easier for operators to predict, determine the slagging state and reduce disturbance as far as possible. Besides, a prediction system has been developed by object-oriented high-level language accordingly.
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Heng, Li Jun, Kun Jie Duan, and Chang Zheng He. "Study on Mathematical Simulation of Nitrogen Oxides (NOx) Formation of Coal-Fired Boiler." Advanced Materials Research 354-355 (October 2011): 319–24. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.319.
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There exist certain limitations to research the law and influence factors of the nitrogen oxides formation only with the help of field tests, because the nitrogen oxides formation of the boiler is influenced by various factors. The flow, combustion mathematical models interrelated and so on are established taking the 410t/h boiler fired tangentially as a prototype by the use of the fluent software. All the mathematical models are verified and modified with the aid of routine field test data, and the accuracy and reliability of the mathematical models are improved. Then NOx formation performance is stimulated in allusion to the influence factors without field test conditions. The mathematical simulation results show that mathematical models can provide a sufficient theoretical basis to analyze accurately combustion and NOx formation law in furnace, and the deficiencies of field tests have been made up.
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Milicevic, Aleksandar, Srdjan Belosevic, Ivan Tomanovic, Nenad Crnomarkovic, and Dragan Tucakovic. "Development of mathematical model for co-firing pulverized coal and biomass in experimental furnace." Thermal Science 22, no. 1 Part B (2018): 709–19. http://dx.doi.org/10.2298/tsci170525206m.
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A comprehensive mathematical model for prediction of turbulent transport processes and reactions during co-combustion of pulverized fuels in furnace fired by 150 kW swirl stabilized-burner has been developed. Numerical simulations have been carried out by using an in-house developed computer code, with Euler-Lagrangian approach to the two-phase flow modelling and sub-models for individual phases during complex combustion process: evaporation, devolatilization, combustion of volatiles, and char combustion. For sub-model of coal devolatilization the approach of Merrick is adopted, while for biomass devolatilization the combination models of Merrick, and of Xu and Tomita are selected. Products of devolatilization of both the pulverized coal and biomass are considered to contain the primary gaseous volatiles and tar, which further decomposes to secondary gaseous volatiles and residual soot. The residual soot in tar and carbon in coal and biomass char are oxidized directly, with ash remaining. For volatiles combustion the finite rate/eddy break-up model is chosen, while for char oxidation the combined kinetic-diffusion model is used. The comprehensive combustion model is validated against available experimental data from the case-study cylindrical furnace. The agreement of the simulations with the data for the main species in the furnace is quite good, while some discrepancies from experimental values are found in the core zone. The presented model is a good basis for further research of co-combustion processes and is able to provide analysis of wide range of pulverized fuels, i. e. coal and biomass. At the same time, the model is relatively simple numerical tool for effective and practical use.
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Adili, Tahmineh, Zohreh Rostamnezhad, Ali Chaibakhsh, and Ali Jamali. "Flame Failures and Recovery in Industrial Furnaces: A Neural Network Steady-State Model for the Firing Rate Setpoint Rearrangement." International Journal of Chemical Engineering 2018 (June 20, 2018): 1–15. http://dx.doi.org/10.1155/2018/3790849.
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Burner failures are common abnormal conditions associated with industrial fired heaters. Preventing from economic loss and major equipment damages can be attained by compensating the lost heat due to burners’ failures, which can be possible by defining appropriate setpoints to rearrange the firing rates for healthy burners. In this study, artificial neural network models were developed for estimating the appropriate setpoints for the combustion control system to recover an industrial fired-heater furnace from abnormal conditions. For this purpose, based on an accurate high-order mathematical model, constrained nonlinear optimization problems were solved using the genetic algorithm. For different failure scenarios, the best possible excess firing rates for healthy burners to recover the furnace from abnormal conditions were obtained and data were recorded for training and testing stages. The performances of the developed neural steady-state models were evaluated through simulation experiments. The obtained results indicated the feasibility of the proposed technique to deal with the failures in the combustion system.
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Glushkov, Dmitrii, Kristina Paushkina, Ksenia Vershinina, and Olga Vysokomornaya. "Slagging Characteristics of a Steam Boiler Furnace with Flare Combustion of Solid Fuel When Switching to Composite Slurry Fuel." Applied Sciences 13, no. 1 (December 29, 2022): 434. http://dx.doi.org/10.3390/app13010434.
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Two interconnected mathematical models have been developed to describe slagging of a steam boiler furnace at the macro and micro levels. The macro-level model is implemented in Ansys Fluent. Using the fuel characteristics and temperature in the furnace, this model can predict the characteristics of ash formation on heat exchanger tubes when the melting temperature of the mineral part of solid fossil fuel is exceeded. The obtained values of slagging rates are used as initial data in the software implementation of the original Matlab microlevel model. Under conditions of dynamic change in the thickness of the slag layer, this model can evaluate the heat transfer characteristics in the hot gas/slag layer/tube wall/water coolant system. The results showed that switching a coal-fired boiler from a solid fossil fuel to a fuel slurry will improve stability and uninterrupted boiler operation due to a lower slagging rate. The combustion of coal water slurries with petrochemicals compared with coal–water fuel is characterized by higher maximum temperatures in the furnace (13–38% higher) and a lower average growth rate of slag deposits (5% lower), which reduces losses during heat transfer from flue gases to water coolant by 2%.
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Ban, Cai Ying, Xu Ao Lu, Jian Meng Yang, Xu Ran, and Feng Ying Liang. "The Partition Period of Thermodynamic Calculation and the Numerical Simulation for Lignite Blended Supercritical Boiler." Advanced Materials Research 1030-1032 (September 2014): 648–52. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.648.
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The purpose of this paper is to study the impact of furnace temperature and load after blending in lignite, based on CFD software FLUENT-6.3,this paper choose the appropriate geometry model and the physical and mathematical models, and numerical simulation of the different conditions 600MW supercritical once-through boiler blending lignite furnace combustion process is curried out. And through a 600MW supercritical coal-fired boiler furnace lignite blended performed sections thermodynamic calculation under different conditions, worked out the furnace flue gas temperature, CO, CO2concentration distribute trend and radiant heat each section surface heat load conditions. The specific amount were blended with 5%, 10%, 15%, 20% were not dried lignite and dried lignite 20% after five conditions. And obtained a conclusion is the temperature and radiation heating surface flue gas heat load in the overall trend under the various conditions.
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Crnomarkovic, Nenad, Srdjan Belosevic, Ivan Tomanovic, and Aleksandar Milicevic. "Influence of the gray gases number in the weighted sum of gray gases model on the radiative heat exchange calculation inside pulverized coal-fired furnaces." Thermal Science 20, suppl. 1 (2016): 197–206. http://dx.doi.org/10.2298/tsci150603206c.
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The influence of the number of gray gases in the weighted sum in the gray gases model on the calculation of the radiative heat transfer is discussed in the paper. A computer code which solved the set of equations of the mathematical model describing the reactive two-phase turbulent flow with radiative heat exchange and with thermal equilibrium between phases inside the pulverized coal-fired furnace was used. Gas-phase radiative properties were determined by the simple gray gas model and two combinations of the weighted sum of the gray gases models: one gray gas plus a clear gas and two gray gases plus a clear gas. Investigation was carried out for two values of the total extinction coefficient of the dispersed phase, for the clean furnace walls and furnace walls covered by an ash layer deposit, and for three levels of the approximation accuracy of the weighting coefficients. The influence of the number of gray gases was analyzed through the relative differences of the wall fluxes, wall temperatures, medium temperatures, and heat transfer rate through all furnace walls. The investigation showed that there were conditions of the numerical investigations for which the relative differences of the variables describing the radiative heat exchange decrease with the increase in the number of gray gases. The results of this investigation show that if the weighted sum of the gray gases model is used, the complexity of the computer code and calculation time can be reduced by optimizing the number of gray gases.
Dissertations / Theses on the topic "Coal-fired furnaces – Mathematical models"
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Boyd, Rodney Kenneth. "Computer modelling of a coal fired furnace." Phd thesis, Mechanical Engineering, 1986. http://hdl.handle.net/2123/5337.
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Correia, Sara Alexandra Chanoca. "Development of improved mathematical models for the design and control of gas-fired furnaces." Thesis, University of South Wales, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369080.
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Shen, Yansong Materials Science & Engineering Faculty of Science UNSW. "Mathematical modelling of the flow and combustion of pulverized coal injected in ironmaking blast furnace." Awarded by:University of New South Wales. Materials Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41108.
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Pulverized coal injection (PCI) technology is widely practised in blast furnace ironmaking due to economic, operational and environmental benefits. High burnout of pulverized coal in the tuyere and raceway is required for high PCI rate operation. A comprehensive review reveals that although there have been a variety of PCI models, there is still an evident need for a more realistic model for PCI operation in blast furnace. Aiming to build a comprehensive PCI model of a full-scale blast furnace, this thesis presents a series of three-dimensional mathematical models, in terms of model development, validation and application, in a sequence from a pilot-scale to a full-scale, from a simple to complicated geometry, from a coal only system to a coupled coal/coke system. Firstly a three-dimensional model of pulverized coal combustion is developed and applied to a pilot-scale PCI test rig. This model is validated against the measurements from two pilot-scale test rigs in terms of gas species composition and coal burnout. The gas-solid flow and coal combustion are simulated and analysed. The results indicate that the model is able to describe the evolutions of coal particles and provide detailed gas species distributions. It is also sensitive to various parameters and hence robust in examining various blast furnace operations. This model is then extended to examine the combustion of coal blends. The coal blend model is also validated against the experimental results for a range of coal blends conditions. The overall performance of a coal blend and the individual behaviours of its component coals are analysed. More importantly, the synergistic effect of coal blending on overall burnout is examined and the underlying mechanisms are explored. It is indicated that such synergistic effect can be optimized by adjusting the blending fraction, so as to compensate for the decreased burnout under high coal rate operation. The model provides an effective tool for the optimum design of coal blends. As a scale-up phase, the coal combustion model is applied to the blowpipe-tuyereraceway region of a full-scale blast furnace, where the raceway is simplified as a tube with a slight expansion. The in-furnace phenomena are simulated and analysed, focusing on the main coal plume. The effect of cooling gas conditions on combustion behaviours is investigated. Among the three types of cooling gas (methane, air, and oxygen), oxygen gives the highest coal burnout. Finally, a three-dimensional integrated mathematical model of pulverized coaVcoke combustion is developed. The model is applied to the blowpipe-tuyere-raceway-coke bed region of a full-scale blast furnace, which features a complicated raceway geometry and coke bed properties. The model is validated against the measurements in terms of coal burnout from a test rig and gas composition from a blast furnace, respectively. The model gives a comprehensive full-scale picture of the flow and thermo-chemical characteristics of PCI process. The typical operational parameters are then examined in terms of coal burnout and gas composition. It is indicated that the final burnout along the tuyere axis is insensitive to some operational parameters. The average burnout over the raceway surface can better represent the amount of unburnt coal particles entering the surrounding coke bed and it is also found to be more sensitive to the changes of most parameters. In addition, the underlying mechanisms of coal combustion are obtained. The coal burnout strongly depends on both oxygen availability and residence time. The existence of recirculation region gives a more realistic coal particle residence time and burnout. Compared with the fore-mentioned two models, this model is considered as a more comprehensive model of PCI operation for understanding the infurnace behaviours and provides more reliable information for the design of operational parameters.
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Ko, Daekwun. "A numerical study of solid fuel combustion in a moving bed." Thesis, 1993. http://hdl.handle.net/1957/35623.
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Coal continues to be burned by direct combustion in packed or moving bed in
small size domestic furnaces, medium size industrial furnaces, as well as small power
stations. Recent stringent restrictions on exhaust emissions call for a better
understanding of the process of combustion of coal in beds.
The present study is a prelude to developing methods of analysis to obtain this
improved understanding. A one-dimensional steady-state computational model for
combustion of a bed of solid fuel particles with a counterflowing oxidant gas has
been developed. Air, with or without preheating, is supplied at the bottom of the bed.
Spherical solid fuel particles (composed of carbon and ash) are supplied at the top of
the bed. Upon sufficient heating in their downward descent, the carbon in particles
reacts with oxygen of the flowing gas.
The governing equations of conservation of mass, energy, and species are
integrated numerically to obtain the solid supply rate whose carbon content can be
completely consumed by a given gas supply rate. The distributions of solid and gas
temperatures, of concentrations of various gas species, of carbon content in solid, and
of velocity and density of gas mixture are also calculated along the bed length. The
dependence of these distributions on the solid and gas supply rates, the air supply
temperature, the size of solid fuel particle, and the initial carbon content in solid is
also investigated.
The calculated distributions are compared with the available measurements
from literature to find reasonable agreement. More gas supply is needed for complete
combustion at higher solid supply rate. At a given gas supply rate, more solid fuel
particles can be consumed at higher gas supply temperature, for larger particle size,
and for lower initial carbon content in solid. The temperature of the bed becomes
higher for higher solid supply rate, higher gas supply temperature, larger solid
particle diameter, or lower initial carbon content in solid. These reasonable results
lead one to encourage extension of the model presented here to more complex
problems involving combustion of coals in beds including the effects of drying and
pyrolysis.Graduation date: 1994
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Eichhorn, Niels Wilhelm. "Combustion modelling of pulverised coal boiler furnaces fuelled with Eskom coals." Thesis, 1998. http://hdl.handle.net/10539/22714.
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A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the degree of Master in Science in
Engineering,
Johannesburg September 1998Combustion modelling of utility furnace chambers provides a cost efficient means to extrapolate the combustion behaviour of pulverised fuel (pf) as determined from drop tube furnace (DTF) experiments to full scale plant by making use of computational fluid dynamics (CFD). The combustion model will be used to assimilate essential information for the evaluation and prediction of the effect of • changing coal feedstocks • proposed operational changes • boiler modifications. TRI comrnlssloned a DTF in 1989 which has to date been primarily used for the comparative characterisation of coals in terms of combustion behaviour. An analysis of the DTF results allows the determination of certain combustion parameters used to define a mathematical model describing the rate at which the combustion reaction takes place. This model has been incorporated into a reactor model which can simulate the processes occurring in the furnace region of a boiler, thereby allowing the extrapolation of the DTF determined combustion assessment to the full scale. This provides information about combustion conditions in the boiler which in turn are used in the evaluation of the furnace performance. Extensive furnace testwork of one of Eskom's wall fired plant (Hendrina Unit 9) during 1996, intended to validate the model for the ar plications outlined above, included the measurement {If : • gas temperatures • O2, C02, CO, NOx and S02 concentrations • residence time distributions • combustible matter in combustion residues extracted from the furnace • furnace heat fluxes. The coal used during the tests was sampled and subjected to a series of chemical and other lab-scale analyses to determine the following: • physical properties • composition • devolatilisation properties " combustion properties The same furnace was modelled using the University of Stuttgart's AIOLOS combustion code, the results of Which are compared with the measured data. A DTF derived combustion assessment of a coal sampled from the same site but from a different part of the beneficiation plant, which was found to burn differently, was subsequently used in a further simulation to assess the sensitivity of the model to char combustion rate data. The results of these predictions are compared to the predictions of the validation simulation. It was found that the model produces results that compare well with the measured data. Furthermore. the model was found to be sufficiently sensitive to reactivity parameters of the coal. The model has thereby demonstrated that it can be used in the envisaged application of extrapolating DTF reactivity assessments to full scale plant. In using the model, it has become apparent that the evaluations of furnace modifications and assessments of boiler operation lie well within the capabilities of the model.
MT2017
Books on the topic "Coal-fired furnaces – Mathematical models"
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Correia, Sara Alexandra Chanoca. Development of improved mathematical models for the design and control of gas-fired furnaces. 2001.
Find full textBook chapters on the topic "Coal-fired furnaces – Mathematical models"
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Harb, J. N., P. N. Slater, and G. H. Richards. "A Mathematical Model for the Build-Up of Furnace Wall Deposits." In The Impact of Ash Deposition on Coal Fired Plants, 637–44. Boca Raton: Routledge, 2022. http://dx.doi.org/10.1201/9780203736616-56.
Full textConference papers on the topic "Coal-fired furnaces – Mathematical models"
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Ward, J., S. J. Wilcox, O. H. Tan, C. K. Tan, R. J. Payne, and D. R. Garwood. "Simulation of a Range of Thermal Systems by Artificial Neural Networks." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24284.
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Abstract The Mechanical & Manufacturing Engineering Research Unit at the University of Glamorgan has been involved for the last 5 years in the application of neural networks to simulate the behaviour of a range of high temperature systems. Consequently this paper presents results from a number of studies concerned with boilers, furnaces and heat treatment processes. The first of these studies involves the prediction of heat transfer rates from air-assisted atomised water sprays for cooling aerospace forgings from high temperatures using the nozzle air and water pressures as inputs to the network. The second case is concerned with prediction of pollutant emissions from a coal-fired boiler using previous measured emission concentrations and an indication of the current boiler load and combustion air flow rate. In both these cases experimental results were used to train the networks. The final example deals with the prediction of load temperatures in an intermittently operated, gas-fired, metal reheating furnace. In contrast, in this example, data generated from a previously validated mathematical model of the furnace were employed for training purposes. Artificial neural networks were found to provide adequate representation of all three systems.
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Correia, Sara A. C., John Ward, and João L. V. A. Sousa. "Numerical Prediction of the Transient Operation of a Gas-Fired Reheating Furnace." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1660.
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Abstract The well-known “zone method”, treats thermal radiation in an enclosure in a global manner so that reliable estimates of this mode of heat transfer can be obtained in systems such as gas-fired furnaces. Consequently the paper employs a two-dimensional thermal radiation model in which both the height and length of the furnace was divided into surface and volume zones. An isothermal computational fluid dynamics simulation was used to estimate the relative mass flow rates, and hence enthalpy flows, into or out of each volume zone. This simplified approach was considered to provide a reasonable estimate of the appropriate inter-zone mass flows since the use of small-scale experimental, near ambient temperature models has been shown in the past to give useful data on flow related behaviour of combustion systems. The computing times resulting from the coupling of a multi-zone model with a single isothermal computation of the flows are relatively short so that the transient performance of the reheating furnace can be analysed. The mathematical model was thus used to predict the fuel consumptions and load temperatures in a gas-fired furnace heating steel bars to a nominal discharge temperature of 1250°C over a typical transient operating period of 8 hours including the start-up from cold. The influences of burner geometry as well as the effects of changes to the value of the roof set point temperature which was used to control the thermal input to the burners were studied. The effects of varying the position of the roof temperature control sensor relative to the burners and of changes in the roof construction were also investigated.
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Zhu, Zaixing, Jiemin Zhou, Ying Wang, Ping Zhou, and Aichun Ma. "Numerical Simulation on Fluid Flow and Combustion in a Subcritical Pressure Boiler With Various Hybrid Coal." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68927.
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With a 300t/h Hg1025/18.2-YM13 sub-critical natural circulation tangentially corner-fired boiler serving as a prototype, a realizable k–ε turbulent mathematical model was established. This model used computational fluid dynamics software FLUENT6.2 and unstructured mesh generating technique of Gambit to reduce numerical false diffusion of the computational results. The fluid flow, heat transfer and combustion processes in the boiler were investigated numerically with different types of coal. The simulation data was compared and analyzed. The influences of primary air ratio, excess air ratio, pulverized fuel feeder on the combustion processes have been studied. These results could be of great help in the operation of tangentially fired furnace of pulverized coal boilers.
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Jorgensen, Kris L., Scott A. Dudek, and Mitchell W. Hopkins. "Use of Combustion Modeling in the Design and Development of Coal Fired Furnaces and Boilers." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68349.
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The design and development of industrial combustion systems often involves the use of advanced modeling tools. In pulverized coal combustion these tools must include several different effects: fluid flow, energy transport, radiation heat transfer, chemical reactions, particle transport and combustion, and the interaction between all these models. Advances in modeling the combustion of coal particles have made these tools even more useful in the design and development of coal fired combustion systems. This paper presents a comprehensive combustion model that has been developed to model the combustion processes in coal fired furnaces. This model is described in detail in the current work along with details of the individual sub-models. Examples of modeling results are presented for two applications to demonstrate the usefulness and importance of modeling coal fired furnaces and boilers.
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Jiang, Zeyi, Yan Xie, Peng Jin, Qingguo Xue, and Xinxin Zhang. "Three-Dimensional Mathematical Model of Multiphase Combustion in Full Oxygen Blast Furnace." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17107.
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The complicated combustion of pulverized coal, free coke and cycle gas in the raceway of full oxygen blast furnace (FOBF) is different from the process in a traditional blast furnace. The differences of free nitrogen, cycle gas mixture, increased coal rate and decreased blast temperature contribute to the complexity of reductive conditions with temperature and composition. A three-dimensional CFD model considering the processes in the regions of raceway, blowpipe, deadman and dropping-zone is developed to describe the kinetic, thermal and chemical behaviors of the fuel combustion. The qualitative and quantitative analysis is conducted to evaluate the effects of operating conditions including temperature of cycle gas, injecting rate and particle diameter of pulverized coal. Simulation results show that large amount of pulverized coal injection (PCI) and also cycle gas injection is feasible with the high oxygen concentration for oxygen blast furnace. The coal injecting rate is a sensitive parameter for the combustion effect in raceway and corresponding measures must be considered for the enhancement of PCI. FOBF process could construct stronger reductive atmosphere than traditional blast furnace, which is beneficial to improve the productivity.
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Coelho, P. J., J. L. T. Azevedo, and L. M. R. Coelho. "The Mathematical Modeling of Utility Boilers at IST." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1554.
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Abstract The mathematical modeling of utility boilers is a difficult problem due to the multiplicity of physical phenomena involved and to the interaction between different phenomena. However, reliable models are extremely useful since they can be used to design new equipment, and to optimize and retrofit units in operation. In this paper a survey of the work carried out at Institute superior Técnico (IST) in Lisbon is reported. Only the work based on comprehensive models, i.e., those accounting for all the relevant physical phenomena taking place in the combustion chamber is addressed. The models employed are briefly outlined. Then, four examples of application are given, two of them for coal-fired boilers where the effect of low NOx burners and coal over coal reburning is investigated, and the other two for oil-fired boilers where parallelization of the code and simulation of the convection chamber are reported.
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Correia, Sara A. C., John Ward, Robert J. Tucker, and Jeff Rhine. "Numerical Simulation of the Application of Porous Ceramic Linings in a Gas-Fired Furnace." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41372.
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This paper describes the development and application of a mathematical model, which simulates the installation of a porous ceramic section as a replacement for part of the conventional lining in a continuously operated, high temperature, gas-fired furnace for heating steel bars prior to a hot forming process. The overall model iteratively links a sub-model of the flow and heat transfer through the porous section with a zone model of heat transfer in the furnace chamber. The resultant predicted heat fluxes at the top surface of the load are then used in a finite-difference calculation of conduction through the thickness of the bars to predict the temperature distribution within the load and the thermal performance of the furnace. The model is used to investigate the effects of the size and positioning of the porous lining as well as changes in its emissivity. In addition simulations were undertaken for a range of thermal inputs to the furnace. Overall the predictions demonstrate that the replacement of part of the conventional refractory lining by a porous ceramic section can result in enhanced radiative heat transfer to the load and hence significantly improved furnace performance.
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Ward, John, Sara A. C. Correia, and João L. V. A. Sousa. "The Application of Multi-Zone Thermal Radiation Models to Investigate the Energy Efficiency of a Metal Reheating Furnace Under Start Up Conditions." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0874.
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Abstract The zone method of radiation analysis has been widely used in mathematical models of a range of industrial heating processes. This paper is thus concerned with the use of a two-dimensional, multi-zone model to predict fuel consumptions, heating rates and load temperatures following the “cold start up” of a gas-fired furnace heating steel bars to a nominal discharge temperature of 1250°C. The model takes into account variations in the flows of the combustion products and in particular examines the influence of the re-circulation of these hot gases within the furnace chamber. The predictions of this complex two-dimensional model are compared with those of a one-dimensional so-called “long furnace model” to illustrate the differences resulting from the use of a more sophisticated multi-zone model.
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Ward, John, Robert J. Tucker, Sara A. C. Correia-Eicher, Alex Z. S. Chong, and Jeff Rhine. "The Effect of Installing Porous Refractory Panels on the Transient Start Up Performance of a Gas-Fired Reheating Furnace." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67216.
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The replacement of part of a conventional refractory lining in a furnace by a porous ceramic panel can enhance the thermal efficiency and increase the furnace throughput. If the hot furnace exhaust gases are passed through the panel (instead of leaving through the normal exhaust) heat is transferred, largely by convection, to the fine porous structure. Most of the heat which is recovered in the porous refractory in this fashion is then re-radiated back into the furnace chamber so that the overall radiative heat transfer to the load is substantially enhanced. The paper describes the development, validation and application of a mathematical model which simulates the installation of such a panel in an intermittently operated, gas-fired furnace heating steel bars to temperatures of approximately 1200°C. The overall model iteratively linked a sub-model of the flow and heat transfer through the porous section with a transient zone model of the radiation heat transfer in the furnace chamber. This procedure is then repeated sequentially throughout the period of the furnace operating cycle to predict the overall thermal performance of the furnace. The model was validated by measurements obtained during a series of tests on a gas-fired furnace. The predicted load temperatures and furnace energy consumptions were in good agreement with the corresponding measurements and indicated that reductions in energy consumption of up to 20% can be obtained depending upon the method of operating the furnace. Following the successful validation of the model it was then employed to predict the thermal behaviour of a small furnace heating steel bars or billets from a “cold start up”. The radiative heat transfer to the load was significantly enhanced throughout the heating period and this led to substantial improvements in the thermal efficiency and reductions in the time required to heat the load to its specified discharge temperature.
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Ghenai, C., and I. Janajreh. "Numerical Modeling of Coal/Biomass Co-Firing." In ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55204.
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Biomass co-firing within existing infrastructure of pulverized coal utility boilers is viewed as a practical near-term means of encouraging renewable energy while minimizing capital requirements, maintaining the high efficiency of pulverized coal boilers and reducing the emissions. Numerical investigation of coal/biomass co-firing is presented in this study. Co-combustion of biomass and coal is a complex problem that involves gas and particle phases, along with the effect of the turbulence on the chemical reactions. The transport equations for the continuous phase (gas) and discrete phase (spherical particles) are solved respectively in the Eulerian and Lagrangian frame of reference. The mathematical models used for co-pulverized coal/biomass particles combustion consist of models for turbulent flow (RNG k-ε model); gas phase combustion (two mixture fractions/PDF model: one mixture fraction is used for the fuel (char) and the second for the volatiles); particles dispersion by turbulent flow (stochastic tracking model); coal/biomass particles devolatilization (two competing rates Kobayashi model); heterogeneous char reaction (kinetics/diffusion limited rate model); and radiation (P-1 radiation model). The coal used is a Canadian high sulfur bituminous coal. The coal was blended with 5 to 20% wheat straw (thermal basis) for co-firing. The effect of the percentage of biomass blended with coal on the velocity field, temperature distribution, particles trajectories and pollutant emissions at the exit of the furnace is presented in this paper. One important result is the reduction of NO and CO2 emissions when using co-combustion. This reduction depends on the proportion of biomass (wheat straw) blended with coal.