Journal articles: 'Fluidized-bed combustion Mathematical models'

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Saxena, S. "Mathematical models for fluidized-bed coal combustion and sulfur retention." Energy 13, no. 7 (July 1988): 557–607. http://dx.doi.org/10.1016/0360-5442(88)90011-4.

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Wang, Zhong Jie, Ning Han, and Jia Wang. "The Study on the Fuzzy Control Algorithm for Main Steam Pressure Control of Circulated Fluidized Bed Boiler." Advanced Materials Research 383-390 (November 2011): 2092–96. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.2092.

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The main steam Pressure is one of the most important guidelines on Circulating Fluidized Bed Boiler (CFBB) operation quality and an important part in control system of CFBB. However, It is very difficult to establish the exact mathematical models of controlled objects because the combustion system of circulating fluidized bed boiler is an object that has many features: distributed parameters, nonlinear, time-varying and long time-delaying. it is unfavorable to control it with traditional controller. Therefore , In this paper fuzzy controller is used in controlling main vapor pressure systems of CFBB, and the fuzzy cascade control system is designed. In computer simulation, the fuzzy cascade control system exert stably, and has perfect control effect to main vapor pressure systems of CFBB.

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Ma, Yunpeng, Chenheng Xu, Hua Wang, Ran Wang, Shilin Liu, and Xiaoying Gu. "Model NOx, SO2 Emissions Concentration and Thermal Efficiency of CFBB Based on a Hyper-Parameter Self-Optimized Broad Learning System." Energies 15, no. 20 (October 18, 2022): 7700. http://dx.doi.org/10.3390/en15207700.

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At present, establishing a multidimensional characteristic model of a boiler combustion system plays an important role in realizing its dynamic optimization and real-time control, so as to achieve the purpose of reducing environmental pollution and saving coal resources. However, the complexity of the boiler combustion process makes it difficult to model it using traditional mathematical methods. In this paper, a kind of hyper-parameter self-optimized broad learning system by a sparrow search algorithm is proposed to model the NOx, SO2 emissions concentration and thermal efficiency of a circulation fluidized bed boiler (CFBB). A broad learning system (BLS) is a novel neural network algorithm, which shows good performance in multidimensional feature learning. However, the BLS has several hyper-parameters to be set in a wide range, so that the optimal combination between hyper-parameters is difficult to determine. This paper uses a sparrow search algorithm (SSA) to select the optimal hyper-parameters combination of the broad learning system, namely as SSA-BLS. To verify the effectiveness of SSA-BLS, ten benchmark regression datasets are applied. Experimental results show that SSA-BLS obtains good regression accuracy and model stability. Additionally, the proposed SSA-BLS is applied to model the combustion process parameters of a 300MW circulating fluidized bed boiler. Experimental results reveal that SSA-BLS can establish the accurate prediction models for thermal efficiency, NOx emission concentration and SO2 emission concentration, separately. Altogether, SSA-BLS is an effective modelling method.

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Mladenovic, Milica, Stevan Nemoda, Mirko Komatina, and Dragoljub Dakic. "Numerical simulation of non-conventional liquid fuels feeding in a bubbling fluidized bed combustor." Thermal Science 17, no. 4 (2013): 1163–79. http://dx.doi.org/10.2298/tsci121116007m.

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The paper deals with the development of mathematical models for detailed simulation of lateral jet penetration into the fluidized bed (FB), primarily from the aspect of feeding of gaseous and liquid fuels into FB furnaces. For that purpose a series of comparisons has been performed between the results of in-house developed procedure- fluid-porous medium numerical simulation of gaseous jet penetration into the fluidized bed, Fluent?s two-fluid Euler-Euler FB simulation model, and experimental results (from the literature) of gaseous jet penetration into the 2D FB. The calculation results, using both models, and experimental data are in good agreement. The developed simulation procedures of jet penetration into the FB are applied to the analysis of the effects, which are registered during the experiments on a fluidized pilot furnace with feeding of liquid waste fuels into the bed, and brief description of the experiments is also presented in the paper. Registered effect suggests that the water in the fuel improved mixing of fuel and oxidizer in the FB furnace, by increasing jet penetration into the FB due to sudden evaporation of water at the entry into the furnace. In order to clarify this effect, numerical simulations of jet penetration into the FB with three-phase systems: gas (fuel, oxidizer, and water vapour), bed particles and water, have been carried out.

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Wang, Liu, Zhang, Zhang, and Jin. "Numerical Investigation of Solid-Fueled Chemical Looping Combustion Process Utilizing Char for Carbon Capture." Processes 7, no. 9 (September 6, 2019): 603. http://dx.doi.org/10.3390/pr7090603.

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The in-depth understanding of the gas–solid flow and reaction behaviors, and their coupling characteristics during the chemical looping combustion (CLC) process has the guiding significance for the operation and optimization of a chemical looping combustor. A three-dimensional numerical model is applied to investigate the char-fueled CLC characteristics in a fuel reactor for efficient CO2 separation and capture. Simulations are carried out in a bubbling fluidized bed fuel reactor with a height of 2.0 m and a diameter of 0.22 m. The initial bed height is 1.1 m, and hence the height–diameter ratio of the slumped bed is five. The oxygen carrier is prepared with 14 wt% of CuO on 86 wt% of inert Al2O3. In the process of mathematical modeling, a Eulerian-Eulerian two-fluid model is adopted for both of the gas and solid phases. Gas turbulence is modeled on the basis of a k–ε turbulent model. The reaction kinetics parameters are addressed based upon previous experimental investigations from literature. During the simulation, the gas–solid flow patterns, composition distributions, and reaction characteristics are obtained. Moreover, the effects of solids inventory and fluidizing number on the reaction performance are elucidated in-depth. The results have shown that the reaction rates have close relationship with the flow patterns and the distributions of gas concentrations. Compared to the steam-char gasification over sand, the application of char-fueled CLC can effectively promote the conversion of gasification products. In addition, higher CO2 concentration at the outlet can be achieved by increasing the initial solids inventory or decreasing the fluidizing number. Some calculated values are verified by the previous data, indicating that the current three-dimensional models are reasonable to study the process mechanism of char-fueled CLC.

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Mei, Joseph S., Esmail R. Monazam, and Lawrence J. Shadle. "Flow Regime Study of a Light Material in an Industrial Scale Cold Flow Circulating Fluidized Bed." Journal of Energy Resources Technology 128, no. 2 (March 22, 2006): 129–34. http://dx.doi.org/10.1115/1.2199566.

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A series of experiments was conducted in the 0.3meter diameter circulating fluidized bed test facility at the National Energy Technology Laboratory (NETL) of the U. S. Department of Energy. The particle used in this study was a coarse, light material, cork, which has a particle density of 189kg∕m3 and a mean diameter of 812μm. Fluidizing this material in ambient air approximates the same gas-solids density ratio as coal and coal char in a pressurized gasifier. The purpose of this study is twofold. First, this study is to provide a better understanding on the fundamentals of flow regimes and their transitions. The second purpose of this study is to generate reliable data to validate the mathematical models, which are currently under development at NETL. Utilization of such coarse, light material can greatly facilitate the computation of these mathematical models. Furthermore, the ratio of density of cork to air under ambient conditions is similar to the density ratio of coal to gas at the gasification and pressurized fluidized bed combustion environment. This paper presents and discusses the data, which covered operating flow regime from dilute phase, fast fluidization, and to dense phase transport by varying the solid flux, Gs at a constant gas velocity, Ug. Data are presented by mapping the flow regime for coarse cork particles in a ΔP∕ΔL‐Gs‐Ug plot. The coarse cork particles exhibited different behavior than the published literature measurements on heavier materials such as alumina, sand, FCC, silica gel, etc. A stable operation can be obtained at a fixed riser gas velocity higher than the transport velocity, e.g., at Ug=3.2m∕s, even though the riser is operated within the fast fluidization flow regime. Depending upon the solids influx, the riser can also be operated at dilute phase or dense phase flow regimes. Experimental data were compared to empirical correlations in published literature for flow regime boundaries as well as solids fractions in the upper dilute and the lower dense regions for fast fluidization flow regime. Comparisons of measured data with these empirical correlations show rather poor agreements. These discrepancies, however, are not surprising since the correlations for these transitions were derived from experimental data of comparative heavier materials such as sands, FCC, iron ore, alumina, etc.

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Shimizu, Tadaaki, Mirko Peglow, Kazuaki Yamagiwa, and Masato Tanaka. "Comparison among attrition-reaction models of SO2 capture by uncalcined limestone under pressurized fluidized bed combustion conditions." Chemical Engineering Science 58, no. 13 (July 2003): 3053–57. http://dx.doi.org/10.1016/s0009-2509(03)00157-x.

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de Lasa, Hugo. "The CREC Fluidized Riser Simulator a Unique Tool for Catalytic Process Development." Catalysts 12, no. 8 (August 12, 2022): 888. http://dx.doi.org/10.3390/catal12080888.

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The CREC Riser Simulator is a mini-fluidized bench scale unit invented and implemented in 1992, at the CREC (Chemical Reactor Engineering Centre), University of Western Ontario The CREC Riser Simulator can be operated at short reaction times, in the 3 s to 20 s range. The present review describes and evaluates the original basic concept of the 1992-CREC Riser Simulator Unit, and the improved design of the 2019-CREC Riser Simulator. Both the initial and the enhanced units are specially engineered to allow the rigorous assessment of both catalyst performance and catalytic reaction kinetics. Kinetic parameters of relatively simple and accurate mathematical models can be calculated using experimental data from the CREC Riser Simulator. Since its inception in 1992, the CREC Riser Simulator has been licensed to and manufactured for a significant number of universities and companies around the world. Several examples of scenarios where the CREC Riser Simulator can be employed to develop fluidized bed catalytic and heterogeneous reactor simulations are reported in this review. Among others, they include (a) hydrocarbon catalytic cracking, (b) the catalytic conversion of tar derived biomass chemical species, (c) steam and dry catalytic methane reforming, (d) the catalytic oxydehydrogenation of light paraffins, (e) the catalytic desulfurization of gasoline, and (f) biomass derived syngas combustion via chemical looping. In this review, special emphasis is given to the application of the CREC Riser Simulator to TIPB (tri-iso-propyl-benzene) catalytic cracking and the light paraffins catalytic oxydehydrogenation (PODH).

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Hajra, Sugato, and Abhishek Aditya Patra. "STUDY OF CIRCULATING COAL FLUIDIZED BOILERS." International Journal of Students' Research in Technology & Management 3, no. 6 (September 30, 2015): 396. http://dx.doi.org/10.18510/ijsrtm.2015.363.

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In the days of modernization, industrialization, technological world we find out a new method of steam production with help of coal. This state of act systems are manufactured over a range of 500 TPH.This boilers are highly efficient, multi coal firing capacity, less emission of so2 and nox gases, utilize high ignite cokes, petcoats,washery rejects. This survey paper is intended to comprehensively give an account of domain knowledge related to CFBC boiler. The authors touch upon the design changes which are introduced in the component levels in order to ease the operation, enhance the performance and to meet the regulatory compliance. In addition, salient correlations related to hydrodynamics, heat transfer and combustion are narrated to facilitate the control and system engineers to develop mathematical models using conservation of mass, energy and momentum equations.

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Khasanov, I. R., A. V. Karpov, S. F. Lobova, and N. V. Petrova. "Field modeling of the ﬁre dynamics as an answer to the question about the ﬁre alarm performance." Pozharovzryvobezopasnost/Fire and Explosion Safety 29, no. 5 (December 2, 2020): 40–50. http://dx.doi.org/10.22227/pvb.2020.29.05.40-50.

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Introduction. The performance of a ﬁre alarm needs to be analyzed to answer the question about its compliance with ﬁre safety requirements. This type of research is frequently performed in the course of a forensic ﬁre investigation. Therefore, it is necessary to identify conditions of ﬁre escalation and safe evacuation of people to assess the ﬁre alarm performance.Purposes and objectives. The purpose of this work is the numerical study of the impact, produced by mathematical models of combustion, characteristics of ﬁre loads and locations of ﬁre beds, on ﬁre alarm performance. Methods. Fire dynamics was ﬁeld modeled to achieve the goal of this research. The analysis of ﬂame propagation was performed with regard for various ﬁre bed locations to simulate the ﬁre alarm operation.Results and discussion. The fulﬁllment of safe evacuation conditions for cases of irregular arrangement of smoke detectors was analyzed to develop and test the algorithm for the calculation of the evacuation start time. It is shown that the estimated time of ﬁre detection depends on combustion models employed (their average or complex level), the size of the computational grid, ﬁre load speciﬁcations and the location of the ﬁre bed.Conclusions. It is shown that the results of the ﬁeld modeling of ﬁre propagation and detection time are inﬂuenced by combustion models used, ﬁre load speciﬁcations and the location of the ﬁre bed in relation to smoke detectors. If the ﬁre alarm fails to perform its functions and, consequently, safe evacuation conditions are not fulﬁlled, it is necessary either to improve the combustion model or to compare the modeling results obtained for actual and standard smoke detector location patterns.

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11

Malko, Mihail, Sergey Vasilevich, Andrei Mitrofanov, and Vadim Mizonov. "Development of the Method for Predicting and Calculating the Operation of Sorption Systems for Cleaning the Generator Gas based on Dolomite Use. Part II." Problems of the Regional Energetics, no. 4(52) (November 2021): 31–42. http://dx.doi.org/10.52254/1857-0070.2021.4-52.04.

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At present, instead of a direct combustion of solid fuel, its thermochemical conversion is exten-sively used to produce a generator gas. The use of this technology is connected with the need for gas purification. One of the promising and widely spread sorbents for the purification of the generator gas is dolomite, whose particles compose the active component of the bed filters. Forecasting the technological characteristics of the functioning of the bed filters of a various de-sign is an extremely urgent task. The objective of the study is to develop a method for forecast-ing and calculating the operation of sorption systems for purification of the generator gas based on dolomite. It is achieved by constructing and verifying a mathematical model of the function-ing of the bed sorption filter with a radial-axial flow pattern of the generator gas through the do-lomite filling. The Markov chains theory of a mathematical apparatus is used to design the one-dimensional mathematical model of the process with discrete space and time. The main recurrent balance ratio is formed at each calculation step taking into account the current characteristics of the process, which makes the model nonlinear. The significance of the research is that an approach to the problem of increasing the reliability of the description and reliability of forecasting technological processes in a bed filter was proposed based on the construction of mathematical models of these processes, in which the filter is considered as a system with distributed characteristics, and the calculation was based on local exchange potentials between particles and gas.

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Донской, Игорь Геннадьевич. "Mathematical modelling of woody particles pyrolysis in a fixed bed." Вычислительные технологии, no. 6(23) (January 16, 2019): 14–24. http://dx.doi.org/10.25743/ict.2018.23.6.003.

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Рассмотрена задача термического разложения совокупности последовательно расположенных древесных частиц с учетом внешнего тепломассообмена с газовым потоком и внутренних физико-химических процессов (теплопроводность, диффузия, фильтрация, сушка и химическая реакция). Математическая модель строится из субмоделей одиночных частиц, сопряженных по потокам теплоты и массы. Результаты численных расчетов позволяют исследовать динамическое поведение частиц в условиях плотного слоя, что представляет интерес при проектировании малых энергетических установок на биотопливе. The development of new energy technologies requires the improvement of mathematical models to describe the physical and chemical processes taking place in power plants. The process of wood particles fixed-bed pyrolysis is investigated in this paper: this process takes place both in the traditional combustion of wood fuels in fixed-bed boilers and in energotechnology processes aimed at producing combustible gases and chemical products (tar, charcoal). The problem of pyrolysis of a set of successively located wood particles is considered. Each particle is considered as an object with an internal distribution of temperature, pressure and concentrations. A system of equations is constructed for a single particle, including external heat and mass transfer between the particles and the ambient gas flow combined with internal physicochemical processes (heat conduction, diffusion, filtration, drying and chemical brutto-reaction of the organic mass decomposition producing gases and solid residue). The temperature of the gas in the pores of the particles is equal to the temperature of the solid. Using the model of pyrolysis of a single particle, it is possible to reproduce the known experimental data. The mathematical model of a fixed-bed pyrolysis is based on submodels of single particles, conjugated over heat and mass flows. The interaction between the particles composing the layer is reduced to heat fluxes: radiant heat transfer between the surfaces of adjacent particles occurs in the bed, as well as convective heat transfer between the heated gas and particles. The result is that each next particle layer is heated at a smaller temperature difference. On the one hand, the intensity of heat transfer decreases, on the other hand, the efficiency of using heat increases. The results of numerical calculations make it possible to study the dynamic behavior of particles in a fixed bed, which is of interest in the design of small power plants using biofuels.

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Sriramulu, Suresh, Samir Sane, Pradeep Agarwal, and Tarek Mathews. "Mathematical modelling of fluidized bed combustion." Fuel 75, no. 12 (October 1996): 1351–62. http://dx.doi.org/10.1016/0016-2361(96)00122-6.

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Srinivasan, Raj A., Suresh Sriramulu, Sivakumar Kulasekaran, and Pradeep K. Agarwal. "Mathematical modeling of fluidized bed combustion — 2: combustion of gases." Fuel 77, no. 9-10 (July 1998): 1033–49. http://dx.doi.org/10.1016/s0016-2361(97)00269-x.

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Van der Vaart, Donald R. "Mathematical modeling of methane combustion in a fluidized bed." Industrial & Engineering Chemistry Research 31, no. 4 (April 1992): 999–1007. http://dx.doi.org/10.1021/ie00004a003.

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Cui, Lin Lin, Hua Lai, Xiao Qian Yu, and Ming Jie Qi. "Modeling and Simulation of Circulating Fluidized Bed Boiler Combustion System Based on Neural Network." Advanced Materials Research 706-708 (June 2013): 859–63. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.859.

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According to the multivariable coupling、 large time delay, non-linearity and time-varying and other difficulties of circulating fluidized bed boiler combustion system, a kind of control technology based on neural network to circulating fluidized bed boiler combustion system was presented. Actual parameter data of a paper mill in Kunming and neural network control principle were used in the establishment of a circulating fluidized bed boiler combustion system mathematical model and modified BP neural network algorithm training. Results of MATLAB simulation show that boiler combustion system control precision was effectively improved and good effects in production and application were got.

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Simeiko, K. V. "DEVELOPMENT AND VERIFICATION OF APPROPRIATENESS FOR MATHEMATICAL MODEL OF HEAT BALANCE OF ELECTROTHERMAL FLUIDIZED BED REACTOR." Thermophysics and Thermal Power Engineering 41, no. 2 (December 3, 2018): 35–40. http://dx.doi.org/10.31472/ttpe.2.2019.5.

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Supply of heat through combustion of organic fuel is impossible or economically unviable for the raw of high temperature processes due to it’s technological peculiarities. Some of these processes can be carried out in electrothermal fluidized bed reactors. Development of appropriate mathematical model for heat balance will allow prognostication of capacity needed to carry out specific process and improvement of electrothermal fluidized bed reactor. During the development of mathematical model methods of heat-mass exchange theory were applied. Verification of appropriateness for mathematical model was carried out through comparison of experimental results and calculated values of the amount of heat needed to perform the process of methane pyrolysis in electrothermal fluidized bed and coefficient of thermal efficiency of electrothermal fluidized bed reactor. Comparison with real thermochemical process in electrothermal fluidized bed reactor confirms the appropriateness of mathematical model. Average deviation of mathematical model of heat balance and coefficient of thermal efficiency from obtained experimental values is 5…7 % and 6…9 % respectively. Proposed mathematical model can be applied in design of electrothermal fluidized bed reactors.

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Mladenovic, Milica, Stevan Nemoda, Milijana Paprika, and Ana Marinkovic. "Application of analytical and CFD models of liquid fuels combustion in a fluidized bed." Thermal Science 23, Suppl. 5 (2019): 1627–36. http://dx.doi.org/10.2298/tsci180226317m.

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In Laboratory for Thermal Engineering and Energy of Institute Vinca, University of Belgrade, a 2-D CFD modeling procedure of numerical simulation of unconventional liquid fuel combustion in bubbling fluidized bed has been developed. This procedure is based on a two-fluid Euler-Euler approach modeling a fluidized bed with the determination of the velocities field of gas and particulates in two-phase, granular flows, analog to the kinetic theory of gases. This model describes in detail the unsteady motion of gas and solid phases, the formation and movement of bubbles with the combustion process in the fluidized bed, but temperature profiles calculated by the bed height differ to some extent from the experimentally obtained profiles. This discrepancy is probably due to the inability of a two-fluid CFD model to give a realistic simulation of the liquid fuel mixing in a fluidized bed. Therefore, an analytical model has been developed, where one of the basic assumptions is that the particles are mixed in the vertical direction of fluidized bed mainly by the bubble wakes. The proposed zonal type of calculating procedure is based on Davidson and Harrison two-phase model of the bubbling fluidized bed, where fluidized bed is divided into zones within which material and energy balances are set.

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Nemoda, Stevan, Milijana Paprika, Milica Mladenovic, Ana Marinkovic, and Goran Zivkovic. "Two-dimensional mathematical model of liquid fuel combustion in bubbling fluidized bed applied for a fluidized furnace numerical simulation." Thermal Science 22, no. 2 (2018): 1121–35. http://dx.doi.org/10.2298/tsci170922307n.

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Lately, experimental methods and numerical simulations are equally employed for the purpose of developing incineration bubbling fluidized bed (BFB) facilities. The paper presents the results of the 2-D CFD model of liquid fuel combustion in BFB, applied for numerical simulation of a fluidized bed furnace. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The proposed numerical model comprises energy equations for all three phases (gas, inert fluidized particles, and liquid fuel), as well as the transport equations of chemical components that are participating in the reactions of combustion and devolatilization. The model equations are solved applying a commercial CFD package, whereby the user submodels were developed for heterogenic fluidized bed combustion of liquid fuels and for interphase drag forces for all three phases. The results of temperature field calculation were compared with the experiments, carried out in-house, on a BFB pilot facility. The numerical experiments, based on the proposed mathematical model, have been used for the purposes of analyzing the impacts of various fuel flow rates, and fluidization numbers, on the combustion efficiency and on the temperature fields in the combustion zone.

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Cojbasic, Zarko, Vlastimir Nikolic, Ivan Ciric, and Ljubica Cojbasic. "Computationally intelligent modeling and control of fluidized bed combustion process." Thermal Science 15, no. 2 (2011): 321–38. http://dx.doi.org/10.2298/tsci101205031c.

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In this paper modelling and control approaches for fluidized bed combustion process have been considered, that are based on the use of computational intelligence. Proposed adaptive neuro-fuzzy-genetic modeling and intelligent control strategies provide for efficient combining of available expert knowledge with experimental data. Firstly, based on the qualitative information on the desulphurization process, models of the SO2 emission in fluidized bed combustion have been developed, which provides for economical and efficient reduction of SO2 in FBC by estimation of optimal process parameters and by design of intelligent control systems based on defined emission models. Also, efficient fuzzy nonlinear FBC process modelling strategy by combining several linearized combustion models has been presented. Finally, fuzzy and conventional process control systems for fuel flow and primary air flow regulation based on developed models and optimized by genetic algorithms have also been developed. Obtained results indicate that computationally intelligent approach can be successfully applied for modelling and control of complex fluidized bed combustion process.

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Kulasekaran, Sivakumar, Temi M. Linjewile, and Pradeep K. Agarwal. "Mathematical modeling of fluidized bed combustion 3. Simultaneous combustion of char and combustible gases." Fuel 78, no. 4 (March 1999): 403–17. http://dx.doi.org/10.1016/s0016-2361(98)00163-x.

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Mitrofanov, A. V., O. V. Sizova, N. S. Shpeynova, A. A. Zhemchugov, and S. M. Mikhailova. "A study of stability of difference scheme of Markov counting chain method for fluidization modeling." Vestnik IGEU, no. 4 (August 31, 2021): 65–74. http://dx.doi.org/10.17588/2072-2672.2021.4.065-074.

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Devices with a fluidized bed of granular material are applied in many energy power technology processes. The fluidized bed is a heterogeneous system, so mathematical models assuming its spatial discretization are necessary for its proper description. Markov chain theory is one of the most effective tools for the mathematical description of the fluidized bed structure. Many research papers are devoted to the issues of the theory application when developing mathematical models of various technological processes in the fluidized bed. At the same time, much less attention is paid to the issue of stability analysis of the proposed algorithms. Thus, it is a highly topical issue to analyze the computational stability of models of fluidized bed based on the mathematical principles of the Markov chain theory. The Markov chain approach is used as a mathematical basis for modeling of the flow patterns in a fluidized bed. The parametric identification of the model is performed using the dependencies known from the scientific papers, and the transition matrices are aligned with the physical parameters of the mass flows, which makes the proposed model nonlinear. The mixed criterion of the stability algorithm is formulated. It shows the influence of the spatiotemporal parameters of the problem sampling on the stability of computational procedures. The stability of the difference scheme to calculate formation of a fluidized bed of a monodisperse granular material is studied. The influence of the time sampling frequency on the stability of the resulting solution is considered. The effect of various parameters of the model on the loss of computational stability is estimated. It is proved that the time and spatial sampling frequencies should be chosen as a result of a mixed stability criterion. The study proves that the methodology of the Markov chain theory is an acceptable tool to describe the structure of such particle systems as a fluidized bed. It is established that macro-diffusion parameter of particle motion is the most influential in the process of computational stability loss. Thus, on the one hand, it is relevant to conduct further comparative studies of existing models of macrodiffusion, and on the other hand, it is possible to use models based on the theory of Markov chains considering the proposed stability criterion.

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LI, S., and J. QIAN. "A MATHEMATICAL MODEL FOR EVALUATING FLUIDIZED BED COMBUSTION EFFICIENCY OF OIL SHALE." Oil Shale 9, no. 2 (1992): 97. http://dx.doi.org/10.3176/oil.1992.2.01.

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Volkov, �. P., M. N. Egai, and R. Yu Shakaryan. "Mathematical model of coal combustion in a furnace with a fluidized bed." Journal of Engineering Physics 52, no. 6 (June 1987): 688–95. http://dx.doi.org/10.1007/bf00873424.

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Mitrofanov, A. V., S. V. Vasilevich, M. V. Malko, L. N. Ovchinnikov, and N. S. Shpeynova. "Development of mathematical model of fluidization of particles in presence of internal heat sources." Vestnik IGEU, no. 6 (December 28, 2022): 49–57. http://dx.doi.org/10.17588/2072-2672.2022.6.049-057.

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Devices for heat treatment of bulk media due to the supply of high-temperature agent from an external source are widely used. In this case using the fluidization technique, the thermal agent also performs the function of a fluidizing medium. The ohmic heating of particles directly in the fluidized bed can be considered as an alternative and preferred technology in some cases. However, to organize such processes effectively we need reliable models to predict the structure of the fluidized bed itself, since it largely determines the conductivity, and, hence, the intensity of heating. The fluidized bed is an inhomogeneous heterogeneous system, therefore, mathematical models assuming its spatial discretization are necessary for its adequate description. Thus, the development of such models is an urgent task. The mathematical apparatus of the Markov chain theory is used as a mathematical basis to model the structure of a bulk medium in a fluidized bed. Parametric identification of the model is performed using the dependencies known from the literature. The transition matrices have been aligned with the physical parameters of the mass flows, which makes the proposed model nonlinear. The electrothermal process in the fluidized bed is described at a qualitative level with an assumption that the heating intensity of the representative volume of the bed is inversely proportional to the volume concentration of particles in it. The gas-particle heat and mass transfer process is a limiting factor that determine the asymptotic temperature in the bed. The authors have studied numerically the influence of the structure and expansion of the fluidized bed on the heating intensity of its phases in case we have internal heat sources, the intensity of which is inversely related to the concentration of the solid phase. The influence of various parameters of the model on the formation of the thermal regime in the apparatus is estimated. It is shown that for an appropriate description of processes in the apparatus, its analysis as an object with distributed spatial parameters is necessary. The paper shows that the methodology of the Markov chain approach is an acceptable tool to describe the structure of such particle systems as a fluidized bed. The obtained results of numerical experiments are in good qualitative agreement with the fluidized bed theory. They can be considered as a reliable scientific basis to calculate the system of ohmic heating of media in a fluidized bed.

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Permatasari, Rosyida, Tholudin Mat Lazim, Tono Sukarnoto, and Supriyadi. "Fluidization of Gas-Solid in Atmospheric Bubbling Fluidized Bed Combustor." Applied Mechanics and Materials 819 (January 2016): 265–71. http://dx.doi.org/10.4028/www.scientific.net/amm.819.265.

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The fluidization behavior of a non-reactive gas-solid in the ABFBC was studied. Experiments were conducted using laser based Particle Imaged Velocimetry (PIV) with B Geldart silica sand (diameter, Ø = 300 – 425 μm) in 2 m high cylindrical combustion chamber. The PIV was used to determine the particle velocity distribution in the combustion chamber. The experiments established the distribution of the sand along the height of the combustion chamber. Consequently, 3D CFD simulations were conducted using ANSYS FLUENT 13.0 software, of which their results were compared with the experimental counterpart. The comparison between the results of the developed CFD models and the experimental data showed very close agreement.

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Chen, Z., Mu Lin, J. Ignowski, B. Kelly, T. M. Linjewile, and P. K. Agarwal. "Mathematical modeling of fluidized bed combustion. 4: N2O and NOX emissions from the combustion of char." Fuel 80, no. 9 (July 2001): 1259–72. http://dx.doi.org/10.1016/s0016-2361(01)00007-2.

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Bibrzycki, Jakub, Marco Mancini, Andrzej Szlęk, and Roman Weber. "A char combustion sub-model for CFD-predictions of fluidized bed combustion - experiments and mathematical modeling." Combustion and Flame 163 (January 2016): 188–201. http://dx.doi.org/10.1016/j.combustflame.2015.09.024.

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Poós, T., and V. Szabó. "Determination of entry length of a fluidized bed dryer using volumetric heat transfer coefficient." International Review of Applied Sciences and Engineering 8, no. 1 (June 2017): 57–65. http://dx.doi.org/10.1556/1848.2017.8.1.9.

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Fluidized bed dryers are widely used in several fields of industry. Sufficiently accurate thermal models provide an opportunity to increase the effectiveness of dryers. The required size of a fluidized bed dryer can be defined with the application of mathematical model. This work is aimed at developing mathematical model to investigate the influence of operating parameters in a fluidized bed dryer using volumetric heat transfer coefficient. After the defining the input parameters of the differential equations, the required entry length of the dryer which effective heat and mass transfer between gas and particles takes place can be estimated. The correct estimation of the entry length is useful in optimal design of a fluidized bed dryer. Using the model the impact of the drying parameters can be determined to the required length.

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Wang, Shuang, Qian Wang, Xiumin Jiang, Shannan Xu, Hengsong Ji, Zhixia He, Yamin Hu, and Ru Wang. "Combustion mathematical simulation of single seaweed particle in a bench-scale fluidized bed." Journal of Renewable and Sustainable Energy 7, no. 2 (March 2015): 023137. http://dx.doi.org/10.1063/1.4919357.

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Kijo-Kleczkowska, Agnieszka. "Analysis of cyclic combustion of the coal-water suspension." Archives of Thermodynamics 32, no. 1 (April 1, 2011): 45–75. http://dx.doi.org/10.2478/v10173-011-0003-7.

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Analysis of cyclic combustion of the coal-water suspension Combustion technology of the coal-water suspension creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements, e.g. in the environment protection. Therefore the in-depth analysis is necessary to examine the technical application of coal as a fuel in the form of suspension. The research undertakes the complex investigations of the continuous coal-water suspension as well as cyclic combustion. The cyclic nature of fuel combustion results from the movement of the loose material in the flow contour of the circulating fluidized bed (CFB): combustion chamber, cyclone and downcomer. The experimental results proved that the cyclic change of oxygen concentration around fuel, led to the vital change of both combustion mechanisms and combustion kinetics. The mathematical model of the process of fuel combustion has been presented. Its original concept is based on the allowance for cyclic changes of concentrations of oxygen around the fuel. It enables the prognosis for change of the surface and the centre temperatures as well as mass loss of the fuel during combustion in air, in the fluidized bed and during the cyclic combustion.

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Nemoda, Stevan, Milica Mladenovic, Milijana Paprika, Aleksandar Eric, and Borislav Grubor. "Three phase Eulerian-granular model applied on numerical simulation of non-conventional liquid fuels combustion in a bubbling fluidized bed." Thermal Science 20, suppl. 1 (2016): 133–49. http://dx.doi.org/10.2298/tsci151025196n.

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The paper presents a two-dimensional CFD model of liquid fuel combustion in bubbling fluidized bed. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The model is taking into account also the third - liquid phase, as well as its interaction with the solid and gas phase. The proposed numerical model comprise energy equations for all three phases, as well as the transport equations of chemical components with source terms originated from the component conversion. In the frame of the proposed model, user sub-models were developed for heterogenic fluidized bed combustion of liquid fuels, with or without water. The results of the calculation were compared with experiments on a pilot-facility (power up to 100 kW), combusting, among other fuels, oil. The temperature profiles along the combustion chamber were compared for the two basic cases: combustion with or without water. On the basis of numerical experiments, influence of the fluid-dynamic characteristics of the fluidized bed on the combustion efficiency was analyzed, as well as the influence of the fuel characteristics (reactivity, water content) on the intensive combustion zone.

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Poós, Tibor, and Viktor Szabó. "Application of Mathematical Models Using Volumetric Transfer Coefficients in Fluidized Bed Dryers." Energy Procedia 112 (March 2017): 374–81. http://dx.doi.org/10.1016/j.egypro.2017.03.1079.

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Vogtenhuber, Hannes, Dominik Pernsteiner, and René Hofmann. "Experimental and Numerical Investigations on Heat Transfer of Bare Tubes in a Bubbling Fluidized Bed with Respect to Better Heat Integration in Temperature Swing Adsorption Systems." Energies 12, no. 14 (July 10, 2019): 2646. http://dx.doi.org/10.3390/en12142646.

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In this paper experimental and numerical investigations on heat transfer within a bubbling fluidized bed will be presented with respect to better heat integration in continuous temperature swing adsorption (TSA) processes for biogas upgrading. In the literature, mainly heat transfer measurements with glass or sand particles are carried out, thus special reference measurements with adsorbent material in a fluidized bed are missing. Therefore firstly, a series of experiments were carried out in the fluidized bed test facility to obtain heat transfer coefficients between tube surface and bed which were then compared to calculated heat transfer coefficients to determine whether suitable models were available. Horizontal bare tubes with different arrangements (i.e., single tubes and especially tube bundles) are immersed in fluidized amine layered particles with a mean diameter of 650 μ m which are used in the adsorption industry as adsorbent. The test facility enables a cross-current flow of the solids and gas phase as it prevails in a multi-stage fluidized bed reactor for TSA-applications. The heat transfer measurements with different arrangements and adsorbent material show very similar values in the range of 200 W/m 2 K. The mathematical model for single tubes multiplied by a tube diameter factor shows approximate agreement with the experimental results. However, the mathematical models for tube bundles were not able to predict the measured heat transfer coefficients with the required accuracy. Secondly, a computer fluid dynamics (CFD) program was used to perform a numerical investigation of the test facility using the Euler–Euler method in order to describe the required two-phase characteristic of a fluidized bed. The results of the numerical simulation were compared and validated with the experimental results. Bubbling fluidized bed flow regimes could be reproduced well but the heat transfer coefficients between tube and bed were clearly underestimated. However, a numerical study for a bubbling fluidized bed with external circulation, as used in novel continuous TSA systems, could be carried out and thus a tool for better heat integration measures was developed.

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Butt, Jawad Abdullah, Yasmin Nergis, Ahmad Hussain, Mughal Sharif, and Arjan Das. "Emissions Reduction by Combustion Modeling in the Riser of Fluidized Bed Combustor for Thar Coal Pakistan." Proceedings of the Pakistan Academy of Sciences: B. Life and Environmental Sciences 59, no. 4 (December 21, 2022): 61–70. http://dx.doi.org/10.53560/ppasb(59-4)754.

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Pakistan has experienced a protracted electricity shortage for the past few years. However, despite Pakistan’s abundant coal deposits, modern coal combustion technology is still required to reduce emissions. Pakistan is struggling to utilize its energy resources and currently experiencing an electrical shortage of more than 8000 MW. The research study models the combustion performance in a fluidized bed riser using ANSYS FLUENT software to understand the combustion behavior of low-rank Thar coal. A simple circulating fluidized bed (CFB) combustion riser was modeled for computational fluid dynamics (CFD) to study the hydrodynamics of gas-solid flow in a circulating fluidized bed riser to reduce emissions and operating costs. Three different types of risers/combustors geometries were used center flow, counter flow, and parallel flow. The CFD model for the solids segment with a k-e turbulence model and the viscosity of static particles in the gas segment both showed excellent mixing performance. According to the FLUENT data, the riser/combustor maximum temperature is around 1400 K or 1130 o C at the primary burning sector in the bed center. According to velocity contours, the greatest velocity in the center-oriented riser/combustor peaks at 3.3 m/s. The CO and CO2 both mass fraction counters show maximum concentration in the center geometry, whereas lower CO concentration is found in parallel geometry. The lowest level of NOx is established in the parallel geometry at around 15 ppm, whereas the counter contours establish the maximum level of NOx at about 31 ppm. Circulating Fluidized Bed Combustor is found to be the most advantageous and effective technology for producing power from Thar lignite coal and reducing emissions.

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Atan, Mohd, Mohd Hussain, Mohammad Abbasi, Mohammad Khan, and Muhamad Fazly Abdul Patah. "Advances in Mathematical Modeling of Gas-Phase Olefin Polymerization." Processes 7, no. 2 (January 30, 2019): 67. http://dx.doi.org/10.3390/pr7020067.

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Mathematical modeling of olefin polymerization processes has advanced significantly, driven by factors such as the need for higher-quality end products and more environmentally-friendly processes. The modeling studies have had a wide scope, from reactant and catalyst characterization and polymer synthesis to model validation with plant data. This article reviews mathematical models developed for olefin polymerization processes. Coordination and free-radical mechanisms occurring in different types of reactors, such as fluidized bed reactor (FBR), horizontal-stirred-bed reactor (HSBR), vertical-stirred-bed reactor (VSBR), and tubular reactor are reviewed. A guideline for the development of mathematical models of gas-phase olefin polymerization processes is presented.

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Kijo-Kleczkowska, Agnieszka. "Analysis of Coal With Coal-Mule and Biomass Co-Combustion in Slurry Form/Analiza Współspalania Węgla Z Mułem Węglowym I Biomasą W Postaci Zawiesiny." Archives of Mining Sciences 59, no. 2 (June 1, 2014): 347–66. http://dx.doi.org/10.2478/amsc-2014-0025.

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Abstract Combustion technology of coal-water fuels creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements e. g in the environment protection. Therefore an in-depth analysis is necessary to examine the technical application of coal as energy fuel in the form of suspension. The paper undertakes the complex research of the coal with coal-mule and biomass co-combustion. The mathematical model enables the prognosis for change of the surface and the centre temperatures and a mass loss of the fuel during combustion in air and in the fluidized bed.

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Liu, Xuemin, Hairui Yang, and Junfu Lyu. "Optimization of Fluidization State of a Circulating Fluidized Bed Boiler for Economical Operation." Energies 13, no. 2 (January 13, 2020): 376. http://dx.doi.org/10.3390/en13020376.

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To reduce the auxiliary power consumption and improve the reliability of large-scale circulating fluidized bed (CFB) boilers, we developed energy-saving CFB combustion technology based on the fluidization state re-specification. A calculation model of coal comminution energy consumption was used to analyze the change in comminution energy consumption, and a 1D CFB combustion model was modified to predict the operation parameters under the fluidization state optimization conditions. With a CFB boiler of 480 t/h, the effect of fluidization state optimization on the economical operation was analyzed using the above two models. We found that combustion efficiency presents a nonmonotonic trend with the change in the bed pressure drop and feeding coal size. There are an optimal bed pressure drop and a corresponding feeding coal size distribution, under which the net coal consumption is the lowest. Low bed pressure drop operation achieved by reducing the coal particle size is not beneficial to SO2 and NOx emission control, and the pollutant control cost increases. The effect of fluidization state optimization on the gross cost of power supply can be calculated, and the optimal bed pressure drop can be obtained.

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Korniyenko, Bogdan, and Andrii Nesteruk. "Mathematical modelling of granulation process in fluidised bed (overview of models)." Proceedings of the NTUU “Igor Sikorsky KPI”. Series: Chemical engineering, ecology and resource saving, no. 2 (June 30, 2022): 51–59. http://dx.doi.org/10.20535/2617-9741.2.2022.260349.

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One of the most common methods of making mineral fertilizers is granulation. Fertilizers in the form of granules have a number of advantages over conventional fertilizers in the form of powder or liquid, namely, ease of transportation, well absorbed and less susceptible to weathering from the soil, convenient to use. To obtain solid particles from liquid starting material such as solutions, emulsions or suspensions, the following processes are used: crystallization, granulation, spray drying. Depending on the focus of the study, the fluidized bed granulation process can be modeled at different levels of abstraction. The dynamics of individual particles is modeled on a microscopic scale. The interaction of a particle with a liquid, equipment or other particles is considered. The next rougher level of abstraction is the mesoscale. Here the particles are divided into classes according to their characteristics. It is assumed that the particles of the class have the same properties and dynamics. On a macroscopic scale, the roughest level of approximation, attention is focused on the integral behavior of the whole set of particles. As a result, the selected characteristic values describe the state of the particle layer. There are different approaches to modeling for each scale. It is proposed to describe the microscopic scale using the hydrodynamics model, the mesoscale using the balance model, and the macroscopic scale using the moments method or the Lagrange-Euler model. A combined balance-hydrodynamics model and a multi-chamber balance model that can be used for the tasks of building information technology for fluidized bed granulation process control technology are also considered.

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Han, Xin Feng, Jian Long Li, and Ning Xu. "CFD Simulation of the Fluidized Bed Applied in the Synthesis of Benzene Series Organosilicon." Advanced Materials Research 753-755 (August 2013): 2663–66. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2663.

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The mathematical model of gas-solid flow 2D fluidized bed was established. The CFD simulation was carried out with commercial software FLUENT6.3 by using Eulerian-Eulerian multiphase models, based on the kinetic theory of granular flow and PC-SIMPLE algorithm. In order to provide a basis on optimizing the operating conditions of the fluidized bed applied in benzene series organosilicon reactor, the processes of bubble formation, growth and disappearance under different cases were analyzed.

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Wang, Sheng Dian, Xue Yao Wang, Xiang Xu, and Yun Han Xiao. "Flow Phenomena in the Riser of a Circulating Fluidized Bed." Advanced Materials Research 516-517 (May 2012): 906–9. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.906.

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Numerical simulation of gas-solid two-phase flows in circulating fluidized bed is proved to be a low-cost and high-efficient method to research the instability essence of flow character. In this work, numerical simulation based on the discrete element (DEM) method is applied to analyze behaviors in a rectangular cross-section fluidized bed. The models of physical and mathematical models are introduced in detail, and the schematic of DEM method also described clearly. It indicates that the DEM method may be used as a powerful tool for the simulation of the gas-solid flow.

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Mitrofanov, A. V., V. E. Mizonov, A. N. Belyakov, and N. S. Shpeynova. "Development of stochastic model of particulate coal fluidized bed expansion and axial structure." Vestnik IGEU, no. 6 (December 28, 2020): 68–76. http://dx.doi.org/10.17588/2072-2672.2020.6.068-076.

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Particulate solids are in the state of fluidization at many stages of preparation and treatment of solid fuels. An effective drag force coefficient Cd is used to describe a mechanical contact between gas stream and an individual particle. The evaluation of the effective drag force coefficient is not limited by the force of hydraulic resistance but also includes a set of different forces. This set of forces is rather indeterminate, and a lot of empirical equations for effective drag force coefficient calculations can be found in the scientific papers. Choosing the applicable formula for calculation is often difficult. In addition, it requires taking into account the flow patterns around an individual particle. Thus, a comparative study to examine the most well-known drag force models with a uniform approach to account the flow patterns around an individual particle is important. The Markov chain approach is used as a mathematical basis for modeling of the flow patterns in a fluidized bed. The identification of the model parameters is completed and the complementation of transition matrices with the current physical properties of substances involved into the flow makes the model non-linear. The comparative study of the results obtained with using of the two correlations for drag force coefficient is performed. The stochastic model of fluidized bed expansion and axial structure has been proposed. The comparative analysis of two different scenarios of fluidized bed expansion using different drag force models has been performed. The authors developed and tested the model to describe fluidized bed expansion and axial structure on the basis of the Markov chain approach. The low certainty of physical drag coefficients models under conditions of flow patterns around an individual particle has been shown. The conducted research proves that consistent description of structure inhomogeneity of fluidized bed is possible using the nonlinear mathematical models based on mesoscale level of the object decomposition. Predictive efficiency of similar models is limited by low reliability of formula for calculation of drag force coefficient. Thus, it is possible to state the importance of further comparative research to check different formulas for calculation of gas-particle drag force coefficient in order to provide a reliable forecast of the fluidized bed height.

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Liu, Ya-Ya, Lei Pan, Shan-Jian Liu, Yong-Jun Li, Wei-Dong Liu, and Shuai-Chao Wang. "Modeling and dynamic characteristics of the dense phase region of a biomass-fired circulating fluidized bed combustion system using Modelica." BioResources 15, no. 4 (August 10, 2020): 7443–57. http://dx.doi.org/10.15376/biores.15.4.7443-7457.

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Using Modelica language, a mathematical model combining static and dynamic contributions of the dense phase region of a 130 t/h biomass circulating fluidized bed boiler combustion system was established on MWorks simulation platform. The mathematical model adopted modular packaging to increase the universality of the model, and it used an implicit, high-order, and multi-step Dassl integration algorithm to conduct the simulation. Under the design condition parameters, the relative error between the bed temperature of the dense phase region obtained by the simulation model and the actual temperature was less than 3.8%, which indicated that the static characteristics of the established simulation model were accurate. The effects of biomass feed and primary air volume step changes on the bed temperature, oxygen content in the flue gas, height of the dense phase region, and the bed pressure difference in the dense phase region were investigated. Both the biomass feeding and the primary wind step of 10% reduced the temperature, and it was obvious that the primary wind had a greater impact on the bed temperature. Meanwhile, the primary wind had a greater impact on the bed pressure difference than the biomass feeding.

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Bizon, Katarzyna. "Application of Pseudohomogeneous and Heterogeneous Models in Assessing the Behavior of a Fluidized-Bed Catalytic Reactor." Energies 14, no. 1 (January 3, 2021): 208. http://dx.doi.org/10.3390/en14010208.

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Comparative analysis of the steady-state and transient properties of a bubbling fluidized-bed catalytic reactor obtained according to different mathematical models of the emulsion zone was performed to verify the commonly used assumption regarding the pseudohomogeneous nature of this zone. Four different mathematical models of the fluidized-bed reactor dynamics were formulated, based on different thermal and diffusional conditions at the gas-solid interface and within the catalyst pellet, namely the model based on the assumption of pseudohomogeneous character for the emulsion zone, and a group of two-scale models accounting for the heterogeneous character of this zone. It was demonstrated that, while the pseudohomogeneous model of the emulsion zone predicts almost identical behavior of the reactor at steady-state as the proposed heterogeneous models, it may fail in the prediction of the reactor start-up behavior, especially when dealing with highly exothermic processes run at relatively high fluidization velocity.

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Sierra Jimenez, Valentina, Carlos M. Ceballos Marín, and Farid Chejne Janna. "Simulation of thermochemical processes in Aspen Plus as a tool for biorefinery analysis." CT&F - Ciencia, Tecnología y Futuro 11, no. 2 (December 27, 2021): 27–38. http://dx.doi.org/10.29047/01225383.372.

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The development of tools for the synthesis, design, and optimization of biorefineries requires deep knowledge of the thermochemical processes involved in these schemes. For this project, three models from scientific literature were implemented to simulate the processes: fast pyrolysis in a fluidized bed, fixed-bed, and fluidized-bed gasification using the Aspen PlusTM software. These models allow the user to obtain performance, consumption, and cost parameters necessary for the design and optimization of biorefineries schemes. The fast pyrolysis model encompasses a detailed description of biomass decomposition and kinetics of the process (149 reactions). In the fixed-bed gasification process, seven reactions that model the process have been integrated into two equilibrium reactors that minimize the Gibbs free energy. The model used for fluidized bed gasification considers both hydrodynamic and kinetic parameters, as well as a kinetic model that considers the change in the combustion reaction rate of biomass with oxygen leading to a change in temperature. Due to the complexity and detail of all these models, it was necessary to use FORTRAN subroutines and iterative Excel macros linked to Aspen PlusTM. Finally, the results of each simulation were validated with data from the model sources, as well as experimental results from the literature.

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Kotowicz, Janusz, Adrian Balicki, and Sebastian Michalski. "Thermodynamic evaluation of supercritical oxy-type power plant with high-temperature three-end membrane for air separation." Archives of Thermodynamics 35, no. 3 (September 1, 2014): 105–16. http://dx.doi.org/10.2478/aoter-2014-0023.

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Abstract Among the technologies which allow to reduce greenhouse gas emissions, mainly of carbon dioxide, special attention deserves the idea of ‘zero-emission’ technology based on boilers working in oxy-combustion technology. In the paper a thermodynamic analysis of supercritical power plant fed by lignite was made. Power plant consists of: 600 MW steam power unit with live steam parameters of 650 °C/30 MPa and reheated steam parameters of 670 °C/6 MPa; circulating fluidized bed boiler working in oxy-combustion technology; air separation unit and installation of the carbon dioxide compression. Air separation unit is based on high temperature membrane working in three-end technology. Models of steam cycle, circulation fluidized bed boiler, air separation unit and carbon capture installation were made using commercial software. After integration of these models the net electricity generation efficiency as a function of the degree of oxygen recovery in high temperature membrane was analyzed.

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Chyou, Yau-Pin, Der-Ming Chang, Po-Chuang Chen, Hsiu-Yun Chien, Keng-Tung Wu, and Rei-Yu Chein. "Development of Biomass Gasification Technology with Fluidized-Bed Reactors for Enhancing Hydrogen Generation: Part I, Hydrodynamic Characterization of Dual Fluidized-Bed Gasifiers." Applied Sciences 10, no. 1 (December 18, 2019): 2. http://dx.doi.org/10.3390/app10010002.

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Various means for enhancing hydrogen content in the syngas from gasification of solid biomass in fluidized-bed reactors were investigated in this study. Steam or oxygen-rich gas can be supplied as gasification medium, to improve the syngas characteristics. Alternatively, a so-called “indirect gasification technology” realizes the thermo-chemical conversion processes in dual reactors, respectively, for combustion and gasification, where gaseous streams in between are separated while solid materials are circulated through. Hence, with air as oxidant for combustion this system features the advantage of producing nearly nitrogen-free syngas. Baseline experiments were firstly carried out to identify performance features; then, parametric studies were conducted and positive trends for enhancing hydrogen generation via biomass gasification were revealed. Moreover, hydrodynamic characteristics in dual reactors were comprehensively envisaged in the cold-flow models to facilitate subsequent investigation into thermo-chemical processes. The experimental results indicated that the circulation mass of the bed material driven by the operating air exceeded the design value, which gave a comfortable safety factor of the engineering design. In addition, the average pressure distribution measured by the cyclic operation of the system was similar to that of the published literature. Based on the experimental results of the cold model, the suggestions of the operating tests in the hot model were addressed. Further efforts will be pursued to establish databases for clean energy and carbon abatement technologies.

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Zambrano, D., J. Soler, J. Herguido, and M. Menéndez. "Conventional and improved fluidized bed reactors for dry reforming of methane: Mathematical models." Chemical Engineering Journal 393 (August 2020): 124775. http://dx.doi.org/10.1016/j.cej.2020.124775.

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Kim, Seongil, Sangmin Choi, Jari Lappalainen, and Tae-Ho Song. "Dynamic simulation of the circulating fluidized bed loop performance under the various operating conditions." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 7 (March 27, 2019): 901–13. http://dx.doi.org/10.1177/0957650919838111.

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In a circulating fluidized bed boiler, the large thermal mass and flow characteristics of the solids strongly affect the transient response of the circulating fluidized bed loop temperature, which determines the heat transfer rate to steam flow. Therefore, it is essential to interpret the dynamic response of the solid behavior in the circulating fluidized bed loop for the stable and efficient operation of the circulating fluidized bed boiler. In this study, the dynamic simulation of the solid behavior along with the flue gas flow in a circulating fluidized bed loop was performed by applying the core-annulus approach for the solid-gas flow inside the furnace and selected models for other physical phenomena of the fluidized bed. The circulating fluidized bed loop of a commercial boiler was selected as the target system. Especially, the model simulates the characteristics of the solid behavior, such as the local solid mass distribution, and the solid flow inside the furnace and the circulating solid according to the various operating conditions. These aspects are difficult to measure and quantify in a real power plant. In this paper, the simulated furnace temperature behavior as the representative performance parameter of the circulating fluidized bed loop was discussed along with the qualitative operation experiences reported in the literature. The operating conditions include the feed rate of fuel and air, the particle size, the solid inventory and the solid circulation rate. Furnace temperature behavior was reproduced through the simulation for each operating case in the literature and was analyzed with the solid behavior along with the combustion rate and heat transfer rate of the circulating fluidized bed loop. The simulation enables quantitative evaluation of the effect of the solid behavior on the temperatures of the furnace and return part in the various operating conditions.

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Salomatov, Vladimir, Andrey Gil, Aleksandr Starchenko, and Roman Arkhipov. "Numerical Research Of Influence Of Disperse Composition On Characteristics Of Combustion Of Coal-Fired Circulating Fluidized Bed." Siberian Journal of Physics 11, no. 3 (October 1, 2016): 53–61. http://dx.doi.org/10.54362/1818-7919-2016-11-3-53-61.

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The peculiarity of mathematical modeling of the circulating fluidized bed (CFB) is that the solid phase (fuel and ash particles) is always a polydispersed medium. The paper constructed a mathematical model of gas dynamics, heat and mass transfer and combustion in the furnace volume of CFB steam generator with a highly concentrated content of the dispersed phase in relation to the investigation of processes in aerothermochemical CFB furnace. Taking into account: the turbulent structure of the two-phase flow, radiation heat transfer in a dusty environment, the chemical reaction kinetics of ignition and combustion, the effects of the power and thermal interactions between the particles and the particles with the wall. A model of such an environment has been chosen phenomenological model of interpenetrating continua Rahmatulina HA. The characteristic features of CFB technology are: firstly organized circulation of solid particles; Second, the repeated return unburned coarse fractions in the fluidised bed. As a result, during the low-temperature burn-in CFB increased almost two orders of magnitude compared with torch mode, allowing you to burn the most difficult fuels in the energy sector. Numerical analysis of data showed that the best results on the effects of polydisperse composition for fuel combustion characteristics in CFB process provides a particle size distribution in which a small fraction predominates.

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Journal articles on the topic 'Fluidized-bed combustion Mathematical models'

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