Study on Combustion Performances of Burners in Furnace in Coal Fired Power Plants (original) (raw)
Related papers
Energy, 2018
We report on numerical analysis of the effects of inflow conditions on sub-optimal combustion in a coal-dust utility boiler of 230 MW e , believed to be the cause of the observed high-temperature corrosion on fireside membrane walls in the furnace diffuser. To this purpose, a precursor simulation of coal-air mixture in a real double-swirl burner in its full complexity was carried out, and the results extrapolated to 24 burner exits for the simulation of combustion in the boiler. The simulations were performed using Ansys Fluent CFD software for solving RANS equations for turbulent flow, combustion of dispersed coal-dust particles, species transport and reactions with the standard chemical kinetics and radiation models. The comparison of combustion results obtained with precursor burner simulations and those with the commonly imposed uniform burner-exit properties revealed considerable differences in the furnace diffuser. Especially notable are different distributions of CO and O 2 concentrations in the burner-exits near field, which are suspected to be the precursors of the membrane wall corrosion. The simulation of the burner reveals also a sub-optimal and incomplete coal-air mixing with a consequent non-uniform and asymmetric particles distribution in the mixture entering the furnace.
3-D MODELLING OF PULVERISED-COAL COMBUSTION IN POWER BOILER WITH TANGENTIAL FURNACE
The present paper describes a numerical modelling approach and some distinctive results concerning the performance of pulverized coal-fired boiler with tangential disposition of burners, which belongs to a power station with an electrical output of 120 MW. Fluent CFD software is utilised for creation of a 3-D model of the boiler furnace, including the platen superheater installed in the upper part of the furnace. A standard steady semi-empirical k-ε model is employed for description of the turbulent flow. The coupling of velocity and pressure is achieved by the SIMPLEC method. Coal combustion is modelled by the mixture fraction/PDF approach for the reaction chemistry, with equilibrium assumption applied for description of the system chemistry. Radiation heat transfer is computed by means of the simplified P-N model, based on the expansion of the radiation intensity into an orthogonal series of spherical harmonics.
A Numerical Analysis of Pulverized Coal Combustion in a Multiburner Furnace
Energy & Fuels, 2007
A three-dimensional numerical simulation is applied to a pulverized coal combustion field in a furnace equipped with three burners, and the trajectories of the coal particles with respect to each burner, which are hardly obtained experimentally, are also investigated in detail. Simulation results are compared with experimental results. The results show that the numerical and experimental results are consistent generally. Also, the examination of the particle trajectories shows that most of the unburned carbon originates from the upperstage burner. This result suggests that the overall unburned fraction can be reduced by supplying coal with a low combustibility to lower-or middle-stage burners and supplying coal with a high combustibility to the upper-stage burner.
Three-dimensional Modelling of Coal Combustion in Blast Furnace
ISIJ International, 2008
Pulverized coal injection technology is widely used in blast furnace ironmaking due to economic, operational and environmental benefits. High burnout within the tuyere and raceway is required for high coal injection rate operation. In order to analyze the flow and combustion in the tuyere and raceway more accurately and reliably, a three-dimensional model of coal combustion is developed. 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 compared to our previous model, the present model is able to provide more detailed gas species distributions and better describe the evolutions of coal particles. It is more sensitive to various parameters and hence more robust in examining various blast furnace operations.
Two approaches for numerical simulation of processes in systems for pulverised coal combustion
2005
The paper presents the overall frame, principal steps and some results of numerical modelling of power boiler furnace on pulverised coal, with tangential disposition of the burners. Complex 3D furnace geometry, two-phase turbulent flow, coal combustion, as well as heat transfer, have been emphasized. Two approaches of numerical modelling were employed in the investigation, both based on Euler-Lagrangean two-phase flow concept and gas phase semiempirical k-ε turbulence model. The first approach is based on specially developed comprehensive model of processes in pulverised coal furnace. In the second case, commercial CFD code is utilised for creation of 3-D furnace model. Some distinctive results concerning the examined boiler performance are presented graphically. On a basis of comparison between the simulation predictions and available site measurements, a conclusion can be drawn that the models produce realistic insight into the furnace processes. Qualitative agreement indicates reasonability of the calculations and validates the employed sub-models.
Large Eddy Simulation of coal combustion in a large-scale laboratory furnace
2014
A detailed Large Eddy Simulation (LES) of pulverised coal combustion in a large-scale laboratory furnace is presented. To achieve a detailed representation of the flow, mixing and particle dispersion, a massively parallel LES was performed. Different phenomenological network models were applied and compared to each other in order to obtain the most adequate devolatilization kinetic data for the LES. An iterative procedure allowed to optimise the devolatilization kinetic data for the studied coal and operating conditions. The particle combustion history is studied by analysing particle instantaneous properties giving a perspective on coal combustion that currently is not available by other means than LES. Predicted major species and temperature were compared with measurements and a good agreement was obtained. The finely resolved near burner region revealed that the flame is stabilised very close to the burner. Furthermore, two distinct zones of CO 2 production were found-one in the internal recirculation zone (IRZ) due to gaseous combustion, and one downstream of the vortex breakdown, due to intense char combustion. It was found that particle properties are inhomogeneous within the IRZ, whereas in the external recirculation zone (ERZ) and downstream of the vortex breakdown they were found to be homogeneous.
Comparative Study with Numerical Simulation of Fossil Fuels Combustion for Industrial Furnaces
International Journal for Research in Applied Science and Engineering Technology, 2017
The selection of liquid or gas fuel to be used in an industrial furnace can be of extreme importance, having a direct effect on its performance, of the equipment. These factors are highly dependent on the combustion process and on factors such as the flame shape droplet path, temperature variation and heat flux distributions within the furnace. In the present work, numerical simulations were carried out, using the finite volume method, with the purpose of analyzing and comparing the combustion process inside a furnace when operating with three types of fuel: Pentane, Hexane and Heptane all are reacting with air with different mass flow rate and air velocity. The results will be showing the temperature distribution, droplet profiles, and mass fraction of emissions. Liquid fuels or high hydrocarbon have a great advantages over other low carbon fuels because they are in liquid form so that they are easily vaporized in combustion process and there is no need for compressing the fuels. Simulation results shows that Heptane fuel has released great amount of energy and high temperature profile as compare to other liquid fuels. Emission after the combustion process is lowest in high hydrocarbon fuel because of rapid evaporation and high combustible in nature.
Numerical Model Analysis of Natural Gas Combustion Burners
International Journal of Engineering and Management Sciences
Traditional power plants still the dominating power source for all the major industries and powerdemanding facilities, the most crucial facility for the whole plant operations is the industrial boiler which generatessteam, heating energy or electrical power. Boilers generate energy by combustion. The improvement of combustion efficiency could greatly influence the energy consumption and will make the boiler more efficient and cleaner (less emissions), that’s why it is important to understand the combustion and thermal flow behaviours inside the boiler. Beside experimental testing, computational work nowadays becoming more and more important due to lower cost and acceptable accuracy with minimum error. With numerical calculations method, the computational model created by a Computational Fluid Dynamics (CFD) software could reduce a lot of trial and error on experimental work. In this paper utilizing the ANSYS FLUENT 19.1 software to make crate the combustion model. The ratio of air t...
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright " CFD modeling study was performed for the combustion of the brown coal in a large-scale tangentially-fired furnace. " Performance of the boiler under ten different operating conditions was investigated. " The temperature distributions were better when the turned off burners are set in the opposite direction. " The results showed improvements on the combustion characteristics in comparison with the standard operating case. a b s t r a c t In the present paper, a computational fluid dynamics (CFD) modeling study was performed for the combustion of the brown coal in a large-scale tangentially-fired furnace (550 MW) under different operating conditions. The AVL Fire CFD code has been used to model the combustion processes. The mathematical models of coal combustion with the appropriate kinetic parameters were written and incorporated to the code as user defined functions. These models consist of pulverised coal (PC) devolatilization, char burnout , and heat and mass transfer. The simulation of the PC combustion was carried out using multi-step reaction chemistry mechanisms. The level of confidence of this numerical model was based on the previous validations of the lignite combustion in a lab-scale furnace, as well as the validation parameters of the present furnace at the standard existing conditions in terms of temperature values and species concentrations. Performance of the boiler under ten different operating conditions was investigated. The strategy of operation schemes for the first six combustion scenarios were based on the change of the out-of-service (turned off) burners under full load operation, while the rest cases were carried out at 20% lower and 20% higher loads than the standard operating conditions. The validated model was used to perform the following investigation parameters: furnace gas temperatures, species concentrations (O 2 , CO and CO 2), velocity distributions, and char consumption. The predictions demonstrated that there are good temperature distributions in the furnace when the turned off burners are set in the opposite direction under full load operation. For higher aerodynamic effect, the numerical results showed improvements on the combustion characteristics in terms of species concentrations and char burnout rates in comparison with the standard operating case. The findings of this study provide good information to optimize the operations of the utility tangentially coal-fired boiler with less emission.