scholarly journals CFD ANALYSIS OF PULVERIZED COAL COMBUSTION IN A BLAST FURNACE TUYERE: COMPARISON BETWEEN WSGG AND GG MODELS FOR RADIATION MODELING

2016 ◽  
Vol 15 (2) ◽  
pp. 60
Author(s):  
C. V. Da Silva ◽  
G. Weber ◽  
F. R. Centeno ◽  
F. H. R. França
Keyword(s):  
Blast Furnace ◽  
Radiation Heat Transfer ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Base Case ◽  
Combustion Gases ◽  
Gas Radiation ◽  
Spectral Models ◽  
Industrial Operations ◽  
Radiation Modeling

Combustion processes are being employed for many years, and remains a major source of energy for industrial operations through the conversion of chemical energy in thermal energy, besides being usually accompanied by formation of pollutants. This work presents a numerical investigation using the software Ansys CFX to model the process of combustion of pulverized coal injected into a blast furnace for production of pig iron making a comparison between WSGG and GG spectral models for gas radiation aim to verify the influence on the radiation heat transfer and the temperature field. Since global coal reserves are being constantly reduced, new techniques using coal are being studied. Among some effective techniques, there is the injection of pulverized coal through a tuyere installed at the bottom of the blast furnace. Thus, among the objectives of this work is to obtain information about the pulverized coal burning process injected. Firstly, it will be employed a North American coal as a base case in order to better understand the involved phenomena. Simulations were made using the actual operating conditions of a blast furnace, which uses atmospheric air enriched with oxygen for burning the coal. The same boundary conditions and operation of other investigations were considered in order to validate the model developed for this work, and so that it can be applied in similar situations, either in assessments or in projects of coal injection systems and combustion in blast furnaces. The results include temperature and velocity fields, oxygen concentration, and the formation of CO and CO2 and they are in agreement with data from literature. Comparing the results of this study with the results obtained in the work (Gu et al., 2010) It observed a qualitative similarity between them and also quantitative. Furthermore, it was found that, in this case, modeling the absorption spectrum of the combustion gases resulting in changes in flame form, but did not significantly alter the magnitude of temperatures, since the walls of the equipment are considered adiabatic.

Three-Dimensional Mathematical Model of Multiphase Combustion in Full Oxygen Blast Furnace

2013 ◽  
Author(s):  
Zeyi Jiang ◽  
Yan Xie ◽  
Peng Jin ◽  
Qingguo Xue ◽  
Xinxin Zhang
Keyword(s):  
Blast Furnace ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Oxygen Blast Furnace ◽  
Oxygen Blast ◽  
Reductive Atmosphere

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.

Heat Transfer Analysis in a Blast Furnace Tuyere Nose

2005 ◽  
Author(s):  
David Roldan ◽  
Clifford Tetrault ◽  
Yongfu Zhao ◽  
Mark Atkinson ◽  
Chenn Q. Zhou
Keyword(s):  
Heat Transfer ◽  
Blast Furnace ◽  
Radiation Heat Transfer ◽  
Cooling Water ◽  
Chemical Reactor ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Large Area ◽  
Fuel Gas ◽  
Hot Air

The Blast furnace process is a counter current moving bed chemical reactor to reduce iron oxides to iron for iron/steel making. In the process, tuyeres are used to introduce hot air (blast) and fuel (gas or pulverized coal) into the furnace for combustion. The nose of a tuyere, composed of copper material, that is exposed to a high temperature environment and a cooling water pipe is embedded to prevent melting of the material. In this work, heat transfer and temperature distributions have been analyzed using the computational fluid dynamics commercial software, FLUENT®. The computations have included the cooling water flow and conjugate heat transfer in the tuyere nose. Both convection and radiation heat transfer on the surfaces are included. Different geometry and operating conditions were considered. The results have indicated that insufficient cooling in a large area between the nose inlet and outlet pipe can cause failures of the tuyere nose.

scholarly journals Comparisons of Radiative Heat Transfer Calculations in a Jet Diffusion Flame Using Spherical Harmonics and k-Distributions

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Jian Cai ◽  
Ricardo Marquez ◽  
Michael F. Modest
Keyword(s):  
Spherical Harmonics ◽  
Radiative Heat ◽  
Single Species ◽  
Full Spectrum ◽  
Combustion Gases ◽  
Spectral Models ◽  
Gray Correlation ◽  
Solution Methods ◽  
Radiation Modeling ◽  
Correlation Tables

A new nongray radiation modeling library for combustion gases has been implemented in OpenFOAM. The spectral models for single species include gray, correlation tables and full spectrum k-distributions (FSK) assembled from a narrow-band database. Mixing models for k-distributions include the multiplication and uncorrelated mixture models. Radiative transfer equation solvers for the library include spherical harmonics such as P1, P3, SP3 and SP5 as well as the optically thin approximation. The performance of the different solution methods is compared for accuracy and speed as a tool for future model strategy selection.

scholarly journals INFLUENCE OF BLOWING PARAMETERS AND SLAG REGIME ON SILICON AND SULFUR CONTENT IN BLAST-FURNACE CAST IRON

2021 ◽  
Vol 1 (38) ◽  
pp. 7-14
Author(s):  
M. Kuznetsov ◽  
G. Kryachko
Keyword(s):  
Blast Furnace ◽  
Cast Iron ◽  
Sulfur Content ◽  
Silicon Content ◽  
Furnace Operation ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Noticeable Effect ◽  
Silicon Oxides ◽  
Coal Fuel

At two blast furnaces (BF) with a volume of 1386 and 1500 m³, the influence of the parameters of blast and slag modes on the content of silicon and sulfur in cast iron was investigated. The blast mode was evaluated by the consumption of pulverized coal fuel (PCF) and oxygen, the slag mode was evaluated by its basicity CaO / SiO₂. It was found that the injection of pulverized coal into the hearth of 1500 m³ BF in the range of flow rates from 108 to 120 g/m³·s, and in the hearth of 1386 m³ BF in the range from 90 to 110 g/m³·s was accompanied by a decrease in the silicon content in cast iron. The deterioration of the transition of silicon into cast iron with an increase in the consumption of pulverized coal is explained by the complex effect of factors that retard the reduction of its oxides. Extreme relationships were also established between the intensity of melting in terms of oxygen consumption and the silicon content in the cast iron of the furnaces under study. The extreme dependences of the studied variables are due to the dual effect of the melting intensity on the reduction of silicon oxides: a reduction in the time of contact of the metal with furnace gases reduces the possibility of transition of silicon into metal, and an increase in the volume of the silicon reduction zone improves these possibilities. When operating a 1386 m³ furnace on calcium slag in the range of CaO / SiO₂ basicity change from 0.9 to 1.3 without removing the blast furnace operation periods associated with a change in operating conditions, the absence of dependence of the silicon content in cast iron on the CaO/SiO₂ modulus was found/ In its turn this indicated the complexity of factors influencing the reduction of silicon oxides. In the same range of changes in basicity and different operating modes of the furnace, a noticeable effect of basicity on the sulfur content in cast iron was observed, which indicates the decisive role of basicity in the process of blast-furnace desulfurization.

Comparisons of Radiative Heat Transfer Calculations Using Spherical Harmonics and K-Distributions

2013 ◽  
Author(s):  
Jian Cai ◽  
Michael F. Modest
Keyword(s):  
Spherical Harmonics ◽  
Radiative Heat ◽  
Radiative Transfer Equation ◽  
Single Species ◽  
Combustion Gases ◽  
Spectral Models ◽  
Gray Correlation ◽  
Solution Methods ◽  
Radiation Modeling ◽  
Correlation Tables

A new nongray radiation modeling library for combustion gases has been implemented in OpenFOAM. The spectral models for single species include gray, correlation tables and narrowband k-distributions. Mixing models for k-distributions include the multiplication and uncorrelated mixture models. Radiative transfer equation solvers for the library include spherical harmonics such as P1, SP3 and SP5 as well as the optically thin approximation. The performance of the different solution methods is compared for accuracy and speed as a tool for future model strategy selection.

Fuel-Composition Effects on High-Temperature Corrosion in Industrial/Commercial Boilers and Furnaces: A Review

1985 ◽  
Vol 107 (3) ◽  
pp. 744-757 ◽  
Author(s):  
J. Bellan ◽  
S. Elghobashi
Keyword(s):  
Metal Surfaces ◽  
Review Literature ◽  
Operating Conditions ◽  
Fuel Oil ◽  
Batch Distillation ◽  
Liquid Form ◽  
Combustion Gases ◽  
Initial Fuel ◽  
Trace Compounds ◽  
Ignition And Combustion

In this review, literature relevant to the problems of deposits and corrosion in industrial/commercial furnaces and boilers is analyzed, and the facts are synthesized into a picture that addresses corrosion problems expected with the use of unconventional fuels. Corrosion is found to depend greatly on the phenomena occurring during the combustion of fuel-oil sprays introduced into the furnace. In a first step, the drops that form the spray heat up and evaporate in a way that closely resembles a batch distillation process. Eventually, ignition and combustion occur with the subsequent change of the liquid fuel drops into carbonaceous, porous, sphere-like particles called cenospheres. In a second step, these cenospheres burn and the products of this combustion step determine the majority of the deposits on metal surfaces. This observation is very important since nonvolatile, non-combustible, corrosive trace compounds existing in the initial fuel-oil drop will have a much higher concentration in the cenosphere than in the original fuel. Accordingly, it is recommended that the theoretical and experimental study of oil spray combustion, cenosphere formation, and cenosphere combustion in a cloud of cenospheres receive a very high priority. Corrosion by gases is found to be unimportant. Deposits are found to be much more corrosive when in liquid form, although corrosion by solid deposits is by no means negligible. As a result, it is suggested in the study that corrosion on highly polished metal surfaces should be studied in order to evaluate the potential of this method of inhibiting deposition and thus hindering corrosion. Recent advances in the theory of deposition from combustion gases are also outlined in this study. The literature survey shows that the main corrosion-causing fuel constituents present in unconventional fuels are sulfur, alkali, vanadium, carbon and carbon monoxide, iron, and chloride. It is found that sometimes one of these compounds might act as a catalyst in corrosive reactions initiated by another compound, and therefore great care must be taken to identify the corrosion-causing compound in the deposits on metal surfaces. It is also found that in some cases a corrosive compound will inhibit the corrosive action of another corrosive compound. It is recommended that such situations be studied further so as to investigate the possibility of an optimum concentration of two such corrosive compounds that would minimize metal wastage. The problem of performing meaningful corrosion experiments is also addressed in this report and specific recommendations are made to achieve this goal. Finally, the effects of additives and the furnace operating conditions are discussed, and potential problems with both additives and new operating conditions are mentioned. The recommendations at the end of this study present a comprehensive set of areas to be investigated in order to better understand and be able to mitigate corrosion problems associated with unconventional fuels. High-priority experimental and theoretical studies are also outlined.

Parametric height influence analysis on thermal radiation and convection applied to real ovens

2021 ◽  
pp. 095440892110375
Author(s):  
Sílvio Aparecido Verdério Júnior ◽  
Vicente Luiz Scalon ◽  
Santiago del Rio Oliveira ◽  
Elson Avallone ◽  
Paulo César Mioralli ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Numerical Models ◽  
Radiation Heat Transfer ◽  
Geometric Optimization ◽  
Operating Conditions ◽  
High Productivity ◽  
Order Of Magnitude ◽  
Lower Height ◽  
Heat Exchanges

Due to their greater flexibility in heating and high productivity, continuous tunnel-type ovens have become the best option for industrial processes. The geometric optimization of ovens to better take advantage of the heat transfer mechanisms by convection and thermal radiation is increasingly researched; with the search for designs that combine lower fuel consumption, greater efficiency and competitiveness, and lower costs. In this sense, this work studied the influence of height on heat exchanges by radiation and convection and other flow parameters to define the best geometric height for the real oven under study. From the dimensions and real operating conditions of continuous tunnel-type ovens were built five numerical models of parametric variation, which were simulated with the free and open-source software OpenFOAM®. The turbulent forced convection regime was characterized in all models. The use of greater heights in the ovens increased and intensified the recirculation regions, reduced the rates of heat transfer by thermal radiation, and reduced the losses of heat by convection. The order of magnitude of heat exchanges by radiation proved to be much higher than heat exchanges by convection, confirming the results of the main references in the technical-scientific literature. It was concluded that the use of ovens with a lower height provides significant increases in the thermal radiation heat transfer rates.

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