skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Numerical analysis for the multi-phase flow of pulverized coal injection inside blast furnace tuyere

Abstract

The pulverized coal injection (PCI) system was modified from single lance injection into double lance injection at No. 3 Blast Furnace of CSC. It is beneficial to reduce the cost of coke. However, the injected coal was found very close to the inner wall of the tuyere during the operation, such as to cause the possibility of erosion for the tuyere. In this study a three-dimensional mathematical model has been developed based on a computational fluid dynamics software PHOENICS to simulate the fluid flow phenomena inside blast furnace tuyere. The model was capable of handling steady-state, three-dimensional multi-phase flow of pulverized coal injection. The model was applied to simulate the flow patterns of the injection coal inside the tuyere with two kinds of lance design for the PCI system. The distribution of injection coal was simulated such as to estimate the possibility of erosion for the tuyere. The calculated results agreed with the operating experience of CSC plant and the optimum design of double lance was suggested. The model was also applied to simulate the oxygen concentration distribution with these different oxygen enrichments for the coal/oxygen lance system. The calculated results agreed with the experimental measurement. These test results demonstratemore » that the model is both reasonably reliable and efficient.« less

Authors:
 [1]
  1. Diwan College of Management, Tainan (Taiwan)
Publication Date:
OSTI Identifier:
20647589
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Mathematical Modelling; Journal Volume: 29; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; INJECTION; COAL; PULVERIZED FUELS; BLAST FURNACES; MATHEMATICAL MODELS; FLUID FLOW; COMPUTERIZED SIMULATION; THREE-DIMENSIONAL CALCULATIONS; DESIGN; OXYGEN; TWO-PHASE FLOW

Citation Formats

Chen, C.W. Numerical analysis for the multi-phase flow of pulverized coal injection inside blast furnace tuyere. United States: N. p., 2005. Web. doi:10.1016/j.apm.2004.11.004.
Chen, C.W. Numerical analysis for the multi-phase flow of pulverized coal injection inside blast furnace tuyere. United States. doi:10.1016/j.apm.2004.11.004.
Chen, C.W. Thu . "Numerical analysis for the multi-phase flow of pulverized coal injection inside blast furnace tuyere". United States. doi:10.1016/j.apm.2004.11.004.
@article{osti_20647589,
title = {Numerical analysis for the multi-phase flow of pulverized coal injection inside blast furnace tuyere},
author = {Chen, C.W.},
abstractNote = {The pulverized coal injection (PCI) system was modified from single lance injection into double lance injection at No. 3 Blast Furnace of CSC. It is beneficial to reduce the cost of coke. However, the injected coal was found very close to the inner wall of the tuyere during the operation, such as to cause the possibility of erosion for the tuyere. In this study a three-dimensional mathematical model has been developed based on a computational fluid dynamics software PHOENICS to simulate the fluid flow phenomena inside blast furnace tuyere. The model was capable of handling steady-state, three-dimensional multi-phase flow of pulverized coal injection. The model was applied to simulate the flow patterns of the injection coal inside the tuyere with two kinds of lance design for the PCI system. The distribution of injection coal was simulated such as to estimate the possibility of erosion for the tuyere. The calculated results agreed with the operating experience of CSC plant and the optimum design of double lance was suggested. The model was also applied to simulate the oxygen concentration distribution with these different oxygen enrichments for the coal/oxygen lance system. The calculated results agreed with the experimental measurement. These test results demonstrate that the model is both reasonably reliable and efficient.},
doi = {10.1016/j.apm.2004.11.004},
journal = {Applied Mathematical Modelling},
number = 9,
volume = 29,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2005},
month = {Thu Sep 01 00:00:00 EDT 2005}
}
  • Studies were made of features of a blast-furnace smelting technology that involves the injection of natural gas (NG), oxygen (O{sub 2}) and pulverized-coal fuel (PCF) into the hearth. The technology has been implemented in the compensation and overcompensation regimes, which has made it possible to maintain or improve the gas dynamics of the furnace, the conditions for the reduction of iron oxides, the heating of the charge, and PCF combustion in the tuyere zone as PCF consumption is increased and coke use is decreased. Under the given conditions, with the blast having an oxygen content of 25.64-25.7%, the hearth injectionmore » of 131-138 kg PCF and 65-69 m{sup 3} NG for each ton of pig iron has made it possible to reduce coke consumption by 171-185 kg/ton pig (30.2-32.7%), reduce the consumption of comparison fuel by 36-37 kg/ton (5.2-5.3%), and lower the production cost of the pig iron by 43-49 hryvnas/ton (3.7-6.4%). Here, furnace productivity has increased 3.8-6.5%, while the quality of the conversion pig iron remains the same as before. Measures are being implemented to further increase the level and efficiency of PCF use.« less
  • Improvement in the combustion efficiency of pulverized coal (PC) is required to secure good permeability and stable operation in blast furnaces at high PC injection rates. Model simulations and combustion tests in a packed bed were carried out to develop a high-turbulence burner with intense mixing of the pulverized coal flow and hot blast. Simulations of the PC flow in the tuyere indicated that enlargement of the outer diameter would enhance the dispersion and heating of the pulverized coal downstream of the burner. Combustion tests in a furnace with a coke bed then showed that combustion efficiency improved by approximatelymore » 10% with the high-turbulence burner. Temperature measurements and gas sampling were carried out at a tuyere of a blast furnace to examine the effect of the high-turbulence burner under practical conditions. The temperature drop in the main coal stream decreased to 100 K with the high-turbulence burner due to more effective mixing of the coal and hot blast. A carbon dioxide concentration of 0.06% was also detected as a sign of fast ignition. Measurements confirmed that better dispersion and faster ignition were obtained with the high-turbulence burner. The newly developed burner was installed at all tuyeres of No. 5 and No. 6 blast furnaces at Chiba Works to enable increased PC injection rates.« less
  • 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 upper-stage burner. This result suggests that the overall unburned fraction can be reduced by supplying coal with a low combustibility to lower- ormore » middle-stage burners and supplying coal with a high combustibility to the upper-stage burner. 50 refs., 14 figs., 4 tabs.« less
  • A wire mesh reactor has been modified to investigate reactions of coal particles in the tuyeres and raceways of blast furnaces. At temperatures above 1000{sup o}C, pyrolysis reactions are completed within 1 s. The release of organic volatiles is probably completed by 1500{sup o}C, but the volatile yield shows a small increase up to 2000{sup o}C. The additional weight loss at the higher temperature may be due to weight loss from inorganic material. The residence time in the raceway is typically 20 ms, so it is likely that pyrolysis of the coal will continue throughout the passage along the racewaymore » and into the base of the furnace shaft. Combustion reactions were investigated using a trapped air injection system, which admitted a short pulse of air into the wire mesh reactor sweep gas stream. In these experiments, the temperature and partial pressure of O{sub 2} were limited by the oxidation of the molybdenum mesh. However, the tests have provided valid insight into the extent of this reaction at conditions close to those experienced in the raceway. Extents of combustion of the char were low (mostly, less than 5%, daf basis). The work indicates that the extent of this reaction is limited in the raceway by the low residence time and by the effect of released volatiles, which scavenge the O{sub 2} and prevent access to the char. CO{sub 2} gasification has also been studied and high conversions achieved within a residence time of 5-10 s. The latter residence time is far longer than that in the raceway and more typical of small particles travelling upward in the furnace shaft. The results indicate that this reaction is capable of destroying most of the char. However, the extent of the gasification reaction appears limited by the decrease in temperature as the material moves up through the furnace. 44 refs., 12 figs., 6 tabs.« less
  • A suite of tuyere-level coke samples have been withdrawn from a working blast furnace during coal injection, using the core-drilling technique. The samples have been characterized by size exclusion chromatography (SEC), Fourier transform Raman spectroscopy (FT-RS), and X-ray powder diffraction (XRD) spectroscopy. The 1-methyl-2-pyrrolidinone (NMP) extracts of the cokes sampled from the 'bosh', the rear of the 'bird's nest', and the 'dead man' zones were found by SEC to contain heavy soot-like materials (ca. 10{sup 7}-10{sup 8} apparent mass units). In contrast, NMP extracts of cokes taken from the raceway and the front of the 'bird's nest' only contained amore » small amount of material of relatively lower apparent molecular mass (up to ca. 10{sup 5} u). Since the feed coke contained no materials extractable by the present method, the soot-like materials are thought to have formed during the reactions of volatile matter released from the injectant coal, probably via dehydrogenation and repolymerization of the tars. The Raman spectra of the NMP-extracted core-drilled coke samples showed variations reflecting their temperature histories. Area ratios of D-band to G-band decreased as the exposure temperature increased, while intensity ratios of D to G band and those of 2D to G bands increased with temperature. The graphitic (G), defect (D), and random (R) fractions of the carbon structure of the cokes were also derived from the Raman spectra. The R fractions decreased with increasing temperature, whereas G fractions increased, while the D fractions showed a more complex variation with temperature. These data appear to give clues regarding the graphitization mechanism of tuyere-level cokes in the blast furnace. 41 refs., 9 figs., 6 tabs.« less