Oxygen Lance Research Articles

氧枪射流对转炉内钢液喷溅行为的影响研究

氧枪射流对转炉内钢液喷溅行为的影响研究

The Design of the Oxygen Gun with the Powder Injection for Converter

For the process that massive limestone is added into converter directly, the problem of slow slagging and low dephosphorization rate can generate. The transformation of converter oxygen lance has been considered in the paper, realizing the oxygen lance blowing powder of granular limestone slag and the rapid slagging and high efficiency of dephosphorization. Based on 120t converter smelting, the consumption of limestone in this process has been calculated in this paper, and a multi-function oxygen gun has been designed to provide guidance for actual production.

Improvement of the smelting efficiency based on the use of composite nozzles in the oxygen lances of high-capacity converters

The nozzle designs of oxygen lances are proposed, which ensure the improvement of technical and economic parameters of converter smelting and metallurgical quality of steel. The developed solutions make it possible to ensure the operation of composite lance nozzles without possible erosion wear of the supercritical part of the nozzle with an acceptable off-design degree. The cylindrical nozzle allows the supersonic flow of oxygen to be stabilized, the length of the initial and transitional sections of the jet to be increased, which is important for organizing a “tough” blowing of the converter bath at the final stage of the operation in order to reduce the oxidation of metal and slag.

ОЦЕНКА ВЛИЯНИЯ КОНСТРУКЦИЙ МНОГОЯРУСНЫХ КИСЛОРОДНЫХ ФУРМ НА ЭФФЕКТИВНОСТЬ ПРОДУВКИ КОНВЕРТЕРНОЙ ВАННЫ С ДОЖИГАНИЕМ ОТХОДЯЩИХ ГАЗОВ

The aim of the work is to carry out an economic assessment of the effect of various structures of multi-tiered oxygen lances and methods for flushing the converter bath with the afterburning of waste gases on the efficiency of the production of iron-carbon semi-products in a modern metallurgical plant. The study was conducted for the process of steel smelting in converters of combined blowing with supply of oxygen from above and neutral gas through the bottom in the conditions of using conventional and multi-tiered oxygen tuyeres. Studies on the afterburning of converter gas in the converter cavity showed that, in proportion to the increase in the proportion of CO2 in the exhaust gases, the costs of steel production are reduced. Compared with the use of tuyeres of classical construction, they amount to 3.23 US dollars / ton of steel for double-circuit, 6.81 US dollars / ton of steel for bunk, and 11.61 US dollars / ton of steel for three-tier. It was determined that when using the classic design of the upper oxygen tuyere, the lower heat of combustion of the converter gas is 10 MJ / m3. In comparison with the classical design, the two-tier, double-circuit and three-tier tuyeres ensure a reduction in the lower heat of combustion of the converter gas by 8,5; 4.4 and 27.1% (rel.), Respectively. On the basis of the data obtained, it is possible to draw a conclusion about the effectiveness of using the technology of combined blowing of the converter bath with the afterburning of exhaust gases in the converter cavity.

Effect of oxygen flow rate and temperature on supersonic jet characteristics and fluid flow in an EAF molten bath

ABSTRACTA new operation method for the oxygen lance of an electric arc furnace (EAF) was proposed, meeting the simultaneous demand for low oxygen flow rate and high stirring power in a particular smelting stage. When the oxygen flow rate needs to be reduced, the stirring power of the jet can be improved by increasing oxygen temperature properly. Free supersonic jet characteristics at different flow rates and stagnation temperatures were studied by numerical simulation and validated by a jet measurement experiment. The results showed that the designed Mach number can be maintained by coupling adjustment of flow rate and stagnation temperature. Meanwhile, a three-phase, full-scaled numerical model for a commercial 75t EAF with three oxygen lances on the side-wall was established to study the fluid flow in the molten bath. The velocity distribution, cavity profile and total kinetic energy of the EAF bath induced by the impingement of supersonic jets onto the liquid bath were discussed and compared. It was found that the fluid flow characteristics of the EAF molten bath can be improved even if the oxygen flow rate was reduced as long as the oxygen temperature could be increased reasonably.

Effect of methane-hydrogen mixtures on flow and combustion of coherent jets

Coherent jets are widely used in electric arc furnace (EAF) steelmaking to increase the oxygen utilization and chemical reaction rates. However, the influence of fuel gas combustion on jet behavior is not fully understood yet. The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software, and a detailed chemical kinetic reaction mechanism was used in the combustion reaction model. The axial velocity and total temperature of the supersonic jet were measured via hot state experiments. The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained. The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas. Besides, the behavior of the supersonic jet in the subsonic section was also investigated, as it is an important factor for controlling the position of the oxygen lance. The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.

Elaboration of the Thermodynamic Model of Refining the Converter Bath when Blowing through Three-Tier Oxygen Lance

Background. In modern conditions, the BOP-process is the main method of mass use steel product production. At the same time, due to the shortage of high-quality charge materials, resource and energy-saving technologies are particularly relevant. To optimize the BOP-process under modern conditions, it is promising to use improved oxygen lances for top blowing in comparison with known designs.Objective. An important stage in the development of advanced steel production technologies is obtaining information on the thermodynamic model of blowing a converter bath through a three-tier lance with the elaboration of the regularities of oxidation processes within the reaction zone of a 160-ton industrial converter.Methods. The analysis that was carried out has a theoretical nature and is based on the definition of the influence of temperature and pressure on the regularities of oxidation processes within the reaction zones formed when oxygen jets are introduced into the volume of a metal bath, foamed slag-metallic emulsion and waste gases in the working space of the converter. As a thermodynamic parameter, the Gibbs energy was used to estimate the probability of chemical reactions. The pressure effect on the oxidation processes in the converter bath was evaluated in accordance with the Van’t Hoff formula.Results. The thermodynamic features of oxidation processes in the 160-ton BOF bath using a three-tier lance are presented. Primary reaction zone is characterized by the occurrence of oxidation of manganese, silicon, carbon, and iron by gaseous oxygen. In the secondary reaction zone there are chemical reactions of the oxidation of silicon and carbon dissolved in the metal by oxygen, as well as the reduction of iron oxide by carbon. The presence or absence of a slag phase on the melt surface practically does not affect the occurrence probability of chemical transformations within the boundary of primary and secondary reaction zones. The additional secondary oxygen jets are characterized by oxidation of the oxide components of the slag and gas phases.Conclusions. During the research it was clarified the thermodynamical model of the oxidation processes in primary and secondary reaction zones, that were formed due to the interaction of 160-ton BOF bath with the supersonic and sonic oxygen jets flowing out of the separate groups of nozzles (of Laval and cylindrical shapes) of top three-level oxygen lance.

Modelling and Analysis of Oxygen Enrichment to Hot Stoves

The paper presents some research work on applying the oxygen enrichment technique to hot stoves that was carried out in one European RFCS project. In the presented work, both theoretical and practical work was studied. A dynamic model was used to investigate the effects of oxygen enrichment on hot stoves’ performance under the condition that only blast furnace gas was used as the fuel gas. The modelling results showed that SOE will enhance the combustion process in hot stoves by increasing hot blast temperature and shortening the on-gas time, which were further verified by industrial trials performed at an iron-making plant. In addition, CFD modelling was performed by simulating different oxygen levels and lance positions at the burner to avoid the hot spot formation during the combustion.

Разработка методов и алгоритмов системы оценки параметров режимов обезуглероживания и дожигания горючих газов в дуговой сталеплавильной печи

Introduction. Currently, in the Russian metallurgy, waste-gas heat under steelmaking in the electric arc furnace (EAF) is used inefficiently. This determines the urgency of the task to develop methods for СО to СО 2 afterburning degree control under steelmaking in the EAF. Materials and Methods . A mathematical model of the decarburization and combustible gas afterburning modes under the reduced pellets electrosmelting at their continuous feed to the EAF bath is used to solve the problem. The proposed model allows estimating the mode parameters of the decarburization and combustible gas afterburning in the electric arc furnace. The role of the rate of carbon oxidation components in the common mode of decarburization and gas afterburning in the EAF is studied. Research Results . The possibility and efficiency of the CO afterburning by the oxygen beams in the counter gas flow system is experimentally confirmed. This allows accelerate the processes of metal heating and decarburization, as well as improve other technological parameters of the steel electrosmelting. Discussion and Conclusions . The mathematical modeling results show that a new method of supplying oxygen through the oxyfuel burners and the oxygen lance provides an increase in the energy efficiency of the steel electrosmelting in the electric arc furnace.

Numerical simulation and application of oxygen lance in 120t BOF of PANSTEEL

In this study, the numerical simulations were carried out to analyse the structure of the oxygen lance nozzle, the flow conditions of oxygen and the flow status of molten steel in the converter. Through the quantitative comparison of the mixing time of the bath under different angles of oxygen lance nozzle, the angle parameter of the oxygen lance nozzle is finalised to be 16°. There are significant improvements on the industrial applications of optimised oxygen lance 536-16, in which the average time of early slag formed is decreased from 5.25 to 4.1 min, the rate of dephosphorisation is increased from 80.02 to 82.49%, the life of oxygen lance is raised from 428 heats to 800 heats, and all technical-and-economic indexes are improved.

Effect of nozzle twisted oxygen lance on flow field and dephosphorisation rate in converter steelmaking process

The stirring ability and flow field characteristic of conventional and nozzle twisted oxygen lance (Twisted angles are 4°, 8° and 12°, respectively) on the molten bath were analysed. The mixing time, impacting depth and impacting radius are measured. Flow field characteristics of multi-phase flow are calculated by numerical simulation. Compared with conventional oxygen lance at industrial application research, it shows that the 8° oxygen lance could stir molten better in steelmaking process for the 120t dephosphorisation converter. These findings agree well with the experimental results of the water experiments and the numerical simulations. Finally, an optimal twisted angle is determined.

AERODYNAMICS AND TEMPERATURE FIELD FEATURES IN THE MODERN EAF WORKSPACE

The paper presents the results of the design study of the material and heat balance on the existing furnace EAF-120 of company «Danieli». It is shown that the arrival of the heat in the oxidation of iron and other components of the charge is signifi cant, and the thermal regime and the whole process become signs of autogenous process. Signifi cant loss of chemical underburning indicate unsatisfactory organization of aerodynamic fl ows in the amount of working space of the furnace. Using a computer program SolidWorks Flow simulation the aerodynamic fl ow and the temperature fi eld in the cold charge location disposed between the electrodes and the inner wall surface of the furnace has been considered. The authors have recommended the rational way to install oxy-fuel burners, oxygen lances and the eductors for inputting carbonaceous material into the bath of the furnace.

Aerodynamics and temperature field within an arc smelting furnace

Results of analyzing the overall balance of materials, the oxygen balance, and the thermal balance within a 120-t arc smelting furnace are presented. It is found that the heat influx in the oxidation of iron and other batch components is so great that the thermal conditions and the process as a whole become autogenous. The significant losses in complete chemical combustion indicate unsatisfactory organization of the aerodynamic fluxes within the furnace. The aerodynamic fluxes and temperature fields in the region of the cold batch between the electrodes and the inner surface of the furnace wall are discussed on the basis of SolidWorks Flow Simulation software. Recommendations are made regarding the configuration of the gas–oxygen burners, the oxygen lances, and the units for injection of the carbon-based materials into the bath.

FORMATION PECULARITIES OF METALL-SLAG SKULLS ON TWO-LEVEL OXYGEN LANCES AT BLOWING OF CONVERTER BATH

The paper considers technological options of converter melting when using two-level lances of different design. The formation peculiarities of metal and slag scaffold on the surface of two-level oxygen lances at top bath blowing of 160-ton converters, depending on the blowing progress with different levels of foamed slag-metal emulsion formation in the working space of the aggregate are reported. An adjoined three-dimensional mathematical model of hydrodynamic and mass-transferring processes in the slag and metal converter phases is proposed; it can be used for the study of circulation process regularities in the converter cavity at different positions of two-level lance, nozzle number in the upper and lower levels, nozzle angles of inclination, the oxygen consumption through the nozzle and other process parameters. Numerical simulation of metal blowing in a 160-ton converter with the use of two-level lance with fi ve Laval nozzles in the bottom tip and eight nozzles in the top row was carried out. These data form an idea of the nature of the metal and gas and slag phase in the converter.

Power efficiency of intensive cast iron desulfurization in a ladle

The evaluation results of resource- and energy-saving efficiency of improved technological route blast furnace - oxygen steel-making for the conditions of PJSC ArcelorMittal Kryvyi Rih with the application of innovative technologies and devices for the pig iron desulphurization intensification in the ladle, converter melting using dual-flow oxygen lance, slag scull application on the converter lining were presented. The proposed method for sulfur removal from the pig iron before casting to converter provides secure insertion of dispersed magnesium deep into the melt with an intensity of more than 24 kg/min by increasing the interfacial contact surface of gas-magnesium bubbles with the melt at the movement of the lance nozzles, reduction of the specific reactant consumption and treatment duration by 20-25%, and increase in the degree of magnesium recovery to sulfur by 15-19% in comparison with the stationary lance. Using the proposed dual-flow lance design in converter melting improves the thermal balance and prevents process equipment metallization without reducing the unit lining resistance. Blowing of the final slag on the lining by moving gaspowder jets provides the regulation of physicochemical properties of the slag bath and formation of a skull protective layer of increased resistance. Expected cumulative reduction of energy costs in comparison with the standard technologies is 0.973 GJ/t of steel.

Metal-slag buildup at two-level oxygen lances in the converter bath

Converter smelting using various two-level lances is considered. Metal-slag buildup on the lance barrel is investigated in top injection of a 160-t converter bath as a function of the injection time with different degrees of formation of foaming slag-metal emulsion in the converter’s working chamber. A three-dimensional mathematical model of the hydrodynamic and mass-transfer processes in the slag and metallic phases is proposed. This model may be used to study the circulation within the converter cavity, with different lance positions, different numbers of nozzles in the upper and lower levels, different nozzle inclinations, different oxygen flow rates, and so on. Numerical modeling of injection in a 160-t converter using a two-level lance—with five Laval nozzles in the lower row and eight nozzles in the upper row—provides information regarding the motion of the metal and gas-slag phases in the converter.

Design of Acoustic Tubes Array and Application to Measuring Acoustic Loads in Supersonic Airflow

Abstract In the acoustic fatigue experiment for hypersonic vehicle in simulated harsh service environment on ground, acoustic loads on the surface of test pieces of the vehicle need to be measured. However, for the normal microphones without high temperature resistance ability, the near field sound measurement cannot be achieved. In this work, on the basis of previous researches, an acoustic tubes array is designed to achieve the near field measurement of acoustic loads on the surface of the test piece in the supersonic airflow with high temperature achieved by coherent jet oxygen lance. Firstly, the process of designing this acoustic tubes array is introduced. Secondly, the equality of phase differences at the front and at the end of the tubes is stated and proved using a phase differences test with an acoustic tubes array whose design is presented in this text; therefore, the phase differences of signals acquired by microphones can be directly applied to beamforming algorithm to determine the acoustic load source. Finally, using above mentioned acoustic tubes array, measurement of acoustic load, with and without a test piece in the supersonic airflow made by the coherent jet oxygen lance, is conducted respectively, and the measurements results are analyzed.

Coalescence Characteristics of Supersonic Jets From Multi-Nozzle Oxygen Lance in Steelmaking BOF

Hydrodynamic behaviors of multiple supersonic jets, especially their coalescence, are of paramount importance to effective design and operation of the oxygen lance in steelmaking basic oxygen furnace (BOF) but not well understood. This paper presents a numerical study on the coalescence of supersonic jets from the multi-nozzle oxygen lance at a practical Mach number by a compressible and non-isothermal computational fluid dynamics model. The model is firstly validated and then used to study the effects of key variables (i.e. ambient temperature and arrangement of nozzles including inclination angle and number) on coalescence behavior under various operational conditions. The results show that the jets prefer to deviate from their own nozzle axes and tend to coalescence with decreasing ambient temperature/nozzle inclination angle or increasing nozzle number. The attenuations of the velocity and dynamic pressure at the jet centerline are delayed with the increase of ambient temperature or the decrease of nozzle number/inclination angle. The critical condition where the jets are free from interaction is identified with increasing nozzle inclination angle, and the critical value is 25° for the four-nozzle lance considered. The simulation results are then used to estimate the cavity shape and splashing modes in BOFs.

Simulation Study on Performance of Novel Oxygen-coal Lances for Pulverized Coal Combustion in Blast Furnace Tuyere

Pulverized coal injection (PCI) into blast furnace tuyere using two novel oxygen-coal lances has been designed by MCC Company. In this paper, a three-dimensional multi-phase model with Discrete Particle Model (DPM) approach has been developed to examine the performance of the novel oxygen-coal lance for PCI operation. Simulation conditions and properties of the PCI were obtained from the real operation conditions of the blast furnace of 580 m3 with molten iron output of 1775 t/d in the industrial experimental base of MCC Incorporation. The simulation results of novel PCI style were also compared with the results of traditional one. Results show PCI using sing coal lance and single oxygen lance pattern is inferior to the conventional PCI mode. Its disadvantages include low BR increase, poor oxygen utilization level and potential damages to the tuyere. PCI using twin oxygen-coal lances is superior to the conventional PCI pattern. Its advantages include doubled burnout ratio, satisfying oxygen consumption level in the raceway and high temperature zone in a safe distance from the nozzle.

Effect of Ambient Temperature on Characteristics of Jets from Oxygen Lance in BOF Steelmaking

Effect of Ambient Temperature on Characteristics of Jets from Oxygen Lance in BOF Steelmaking