Blast Furnace Tuyere Research Articles

Application of Efficient Channel Attention Residual Mechanism in Blast Furnace Tuyere Image Anomaly Detection

In the steelmaking industry, the state of the blast furnace tuyere is an important basis for obtaining the internal information of the blast furnace. Traditional detections mainly rely on manual experience judgment, which is a time-consuming and tiring procedure for a human. In order to improve the efficiency of the detection, this paper is devoted to applying artificial intelligence methods to blast furnace anomaly detection. However, because of the low imaging degree of the abnormal state monitoring of the furnace mouth, the difference in the abnormal category is inconspicuous, and it is difficulty to extract the features with the existing intelligent models. To solve these problems, a novel and stable method is proposed in this paper to classify the image recognition of the abnormal state of the tuyere into one category; this is a new architecture that combines multiple technologies. For the fine-grained image classification task, an improved abnormal state recognition algorithm of the blast furnace tuyere based on the channel attention residual mechanism is proposed. In the model, the dataset is augmented by rotating it at random angles to balance the amount of data in each category; then, the residual module is used to integrate high- and low-order feature information and optimize the network; then, the multi-layer channel attention module is added based on the channel attention residual mechanism, and it obtains the optimal parameter combination of the model through k-fold cross-validation. Moreover, the number of channels was reduced by half after channel fusion, which could effectively reduce the model parameters and model complexity. It is shown in our experiments that the proposed method has an accuracy rate of 97.10% in identifying the abnormal state of the tuyere in our collection of blast furnace tuyere datasets. In order to test the performance of the proposed method, some existing models, such as SERNet, ResNeXt, and repVGG, are involved for comparison, and the proposed method has a better classification effect in comparison to them.

Temperature field simulation of Ni60A coating with different copper content on blast furnace tuyere

This paper systematically analyzed the heat transfer characteristics of Ni60A coating on the surface of the blast furnace tuyere using ANSYS software. To improve the accuracy of simulation results, the influence of copper dilutions ratio (copper content) on the thermal-physical parameters of the Ni60A coating was considered. The functional expressions between copper content and thermal-physical parameters of coating were created for the first time by the method of nonlinear fitting. Based on the fitting results, the temperature field model of the blast furnace tuyere was calculated by using the fluid-solid thermal coupling algorithm. Compared with the uncoated tuyere, the surface temperature of tuyere was increased by about 309.69 K after cladding a coating with 10% dilution ratio (copper content). However, this temperature is still lower than the allowable temperature of the coating material. With the increase of dilution ratio (copper content), the surface temperature gradually decreased. However, the internal temperature of tuyere substrate exceeded that of the uncoated tuyere when the dilution ratio (copper content) was more than 40%. During the actual cladding process, it is necessary to control the dilution ratio (copper content) of Ni60A coating as far as possible not higher than 40%.

Improvement of the Function of Blast-Furnace Air Tuyeres

Improvement of the Function of Blast-Furnace Air Tuyeres

Failure mode and mechanism of a blast furnace tuyere

In this study, the failure modes of a blast furnace tuyere after service damage were systematically investigated. The high ambient temperature caused grain growth and hardness reduction at the front end of the tuyere. Owing to scraping by gyratory coke in the blast furnace, a perforation formed at the front end of the tuyere, causing damage. Owing to the uneven distribution of components caused by repair welding, cracks occurred in the front coating of the inner wall of the tuyere. The wear of the inner wall of the tuyere was related to the angle and depth of the coal injection gun, and the wear mechanism differed at different positions. Thus, tuyere failure is mainly attributed to the wear of the front end and inner wall. Therefore, it is necessary to develop a coating with excellent high-temperature wear resistance to protect the inner wall and the front end of tuyeres, thereby extending their service life.

Investigation of the influence of design parameters on thermal processes in a blast furnace tuyere using ANSYS software

It is known that the maximum heat losses in a water­cooled tuyere of a blast furnace are in the blowing channel. An effective way to reduce them is to install a heat­insulating ceramic insert. Such inserts installed in the inner cup of air tuyeres for the blast furnace no. 5 of PJSC “Severstal” reduce heat losses through the tuyere by 30 %, and inserts, which, in addition, insulate most of the inner surface of the snout part, further reduce heat losses through the tuyere by 26.2 %. The ANSYS software was used to study the effect of design parameters on thermal processes in a blast furnace tuyere with heat­insulating insert. To make the simulation more realistic the entire air tuyere, including water­cooling circuit, was considered as the modeling object. Protrusion of the insert into the blowing channel by 2 mm improves the mixing of natural gas and blast, promotes gas combustion, which leads to an increase in heat losses through the blowing channel and a decrease in resistance of the insert. To increase durability of the insert and reduce heat losses through the blowing channel, it is justified to use an elongated insert with a thickness varying from 13 to 8 mm in the blowing direction, which does not protrude into the blowing channel, having an angle between the normal to the side of the inner cup and the axis of the hole for natural gas supplying about 30°. It is shown that to obtain the maximum heat content of the blast, which is influenced by the combustion of natural gas and heat losses with cooling water in the blowing channel, it is preferable to have an elongated insert of variable thickness, varying from 10 to 8 mm in the blowing direction, and axis of the hole for natural gas supply perpendicular to the wall of the inner cup.

Intelligent decision support system based on video recognition of the blast furnace tuyeres

An approach to creation of an intelligent system for predicting the state of a technological process in real time is presented. The approach is based on the analysis of a video sequence of images obtained as a result of streaming video by cameras installed on the tuyeres of a blast furnace. Algorithms for recognizing video images of tuyere foci, as well as scenario forecasting of the evolution of technological situations are proposed. A historical background regarding the development of methods for automatic control of the blast-furnace process, in particular, the use of artificial intelligence, is presented. The study is aimed at the ability of rapid analysis of the production situation (PS) and prediction of the PS evolution in the course of functioning of the blast furnace process, which will provide the possibility of timely decisions on adjusting control in an automatic or automated mode. Using the developed algorithm for analysis and prediction of the process dynamics and proceeding from the revealed regularities of the change in video data, a method for early detection of a tendency to the occurrence of certain events on tuyeres, including those leading to the destabilization of the blast furnace process, is proposed. The novelty of the presented approach lies in the fact that not only the state of the process at the next moment of time, but also the most probable chain of several subsequent states is predicted. Real-time forecasting algorithms are based on the construction and replenishment of the base of inductive knowledge — regularities revealed through the intellectual analysis of the revealed information — in the course of real functioning. Methods of studying Markov chains, machine learning and wavelet analysis are used for the associative search for patterns. The algorithms developed by the authors can be used in decision support systems for blast-furnace control. The results of practical research, confirming the effectiveness and viability of the proposed approach, are presented.

Impact of Flow Boiling on Blast Furnace Tuyere Life: A Designer's Perspective

Water‐cooled copper tuyeres of blast furnace are subjected to intense thermal conditions. Several modifications are attempted to prevent tuyere failure as the impact of failure is severe. What has, however, gone unnoticed is the peak “Cold face” temperature in tuyere and its implication. Numerical model incorporating water flow and conjugate heat transfer with a feature to identify onset of boiling by analytical correlations is developed. It is ascertained that, in tuyeres, the temperature of the Cold face exceeds the saturation temperature at the prevailing pressure by an amount high enough to cause nucleate boiling. The implication of the onset of boiling is discussed and a design modification is suggested by changing the aspect ratio of cooling passage. The impact of velocity distribution to achieve lower peak “Cold face” temperature is discussed. Modified design shows almost zero boiling prone zone for the range of operating parameters studied. Fourteen modified tuyeres are placed alongside original designed tuyeres in an blast furnace. The newly designed tuyeres outperform their counterparts. This approach to identifying and suppressing boiling of water in the cooling channel—a hitherto neglected phenomenon—gives an additional input towards designing a more robust tuyere.

Diameter Selection of Blast Furnace Tuyeres Based on the Rate and Energy of the Fuel-Enriched Blast and Tuyere Gas Flows with the Injection of the Pulverized Coal

Diameter Selection of Blast Furnace Tuyeres Based on the Rate and Energy of the Fuel-Enriched Blast and Tuyere Gas Flows with the Injection of the Pulverized Coal

Increasing the Operational Efficiency of Insulation Liners in the Air Passage of Blast-Furnace Tuyeres

Increasing the Operational Efficiency of Insulation Liners in the Air Passage of Blast-Furnace Tuyeres

Effect of CO2 injection into blast furnace tuyeres on the pulverized coal combustion

Abstract CO2 injection into blast furnace tuyeres is a new technology to utilize CO2, aiming at expanding the way of CO2 self-absorption in the metallurgical industry. The decisive factor of whether CO2 can be mixed into a blast-furnace hot blast and the proper mixing ratio is the effect of CO2 injection on pulverized coal burnout. To investigate the effect of CO2 injection into tuyeres on pulverized coal burnout, a three-dimensional mathematical model of pulverized coal flow and combustion in the lower part of the pulverized coal injection lance-blowpipe-tuyere-raceway was established, and the effect of CO2 injection into tuyeres on pulverized coal combustion rate and outlet temperature is analyzed. The numerical simulation results show that the delay of pulverized coal combustion in the early stage is caused by the endothermic effect of the reaction of CO2 with carbon, and the burnout of pulverized coal is increased in the later stage due to the oxidation of CO2.

Simulation of water-circulating path and heat transfer in blast-furnace tuyeres with simple and spiral double-chamfer design

Tuyeres or air-blowing nozzles are considered sensitive parts of blast furnaces responsible for blowing hot air into the furnace, and their proper operation has a direct effect on the iron-melting process in the blast furnace. These parts are usually damaged or destroyed by exposure to high temperatures, radiation, slag or molten iron scattering, improper design of the water-circulating system, low thermal conductivity, operator problems, etc.In this paper, the two simple and spiral water-circulating designs are simulated and examined in heat transfer and fluid pressure drop under furnace conditions. Based on the results obtained from the spiral design, water is directed to the critical areas of the body at a lower temperature and passes through these areas quicker than the simple design.; Additionally, the cooling power of the spiral design is more efficient for the body of the tuyeres and will help prevent this part from burning in these areas. According to the simulation, the spiral design’s water pressure will drop slightly further than the simple design.

Effect of the Step in the Blow Channel of a Blast Furnace Tuyere on Improving Natural Gas Combustion

The paper demonstrates the effect of the step in the blow channel and the insulating lining on the intensity of mixing natural gas with the air blast and its combustion in the blow channel, as well as on the increase in the air blast temperature at the tuyere outlet. This allows to increase natural gas consumption and reduce coke consumption.

Improving the heat insulation efficiency of the blast furnace tuyere

A proposed method to increase the service life of the heat-insulating insert in the air passage of the blast furnace tuyere suggested gluing heat-resistant siliceous fabric onto its outer surface, and to reduce heat loss and increase the tuyere resistance to burnout, fixing a ceramic disk to the end of the tuyere’s nose. The necessity of measures to increase the service life of a heat-insulating insert in the tuyere was justified by simulating its stress state in Ansys. The use of heat-resistant siliceous fabric on the entire outer surface of the insert allowed a more than twofold increase in the insert’s service life compared to the option when the fabric was glued to the insert part from the flange to the gas pipe. Using simulation of the tuyere’s thermal state in a DEFORM–2D environment and industrial experiments, the possibility of reducing heat loss and protecting the tuyere from burnout by thermal insulation of the end of its nose using a ceramic disk is shown.

Failure Analysis and Preventive Measure Proposition of Self-Flow Castable Blow Pipe of Blast Furnace Tuyere Stock for Enhancing Reliability

In this present study, the failure incidents of self-flow castable blow pipe of high volume blast furnace tuyere stock have been critically investigated. Based on failure analysis of failed blowpipes, possible preventive measures have been proposed. High hot blast pressure has been found to be the condition for occurrence of blowpipe failure. Hence, proper regulation of hot blast pressure is of utmost importance as a preventive measure. To analyse the cause of failure, after installation of blowpipe, the shell temperature is measured on a daily basis. It is observed that when the shell temperature crosses 350 °C, blowpipe jamming occurs. According to preventive step proposition, if the temperature crosses 350 °C and attains 480 °C, the blowpipes are advised to be replaced for maintaining the operation of blast furnace. This study has been done in high volume blast furnace where it is found that the impact of failure is immense with regard to productivity and safety. It has also been found that the compendium of this investigation can be replicated in other high volume blast furnaces and can also be extended to any low volume blast furnace.

СИСТЕМА АВТОМАТИЧНОГО РОЗПОДІЛУ ГАРЯЧОГО ДУТТЯ ПО ФУРМАХ ДОМЕННОЇ ПЕЧІ

The article considers the current issue of automatic control of the distribution of the blast through the blast furnace tuyeres. Ensuring a uniform distribution of blast over the furnace hearth allows you to even out the heating around its circumference, improve the distribution of gas flows in the column of charge materials and the full use of chemical and thermal energy of gases. Studies of existing blast distribution systems have shown the reasons for their inoperability. This was because the measuring equipment, the control devices and the actuators do not withstand high temperatures. As a solution to this problem, it was proposed to add carbon fiber in the development of the actuators that will significantly reduce the abrasive wear and increase the resistance to high temperatures. A system of automatic control of the blast distribution for each tuyere separately was also developed. The airflow in the system is measured with Venturi tubes using a variable differential method. Regulation in the system is carried out by means of a carbon fiber-reinforced butterfly valve installed in the fixed knee of the tuyere device befind Venturi tube. In the environment of object-oriented programming, special software for controlling the process of the blast distribution through the tuyeres, its uniform distribution and redistribution between all tuyeres, with the option to set the total flow rate and the flow rate for a single tuyere was developed. Using the developed system of automatic distribution of blast by tuyeres will ensure a uniform supply of blast to the furnace of the blast furnace through separate tuyeres, which will increase the productivity of the furnace itself while reducing coke consumption

Development of information modeling system of coal-dust fuel injection into tuyeres of blast furnace

The article considers a mathematical model of combustion zone of blast furnace working with the use of injection of coal-dust fuel. In this model, two subsystems were identified: 1) subsystem of heating the particles of coal dust and volatiles release in the combustion zone; 2) subsystem of heat exchange and combustion processes in the tuyere. A two-dimensional velocity field of gas in the combustion zone was investigated. The combustion processes are considered as a set of simultaneously developing phenomena of coke burning in a layer, single pieces of coke and particles of coal dust. The model includes following equations: total gas mass balance, gas component mass balance, gas heat balance, movement of coal dust particles and heat balance of coal dust particles. The model calculates maximum burning temperature in combustion zone; the distance from the cut of the tuyere to the focus of combustion; the length of the oxygen combustion zone; gas temperature; the content of gas phase components and the degree of carbon burnout of pulverized coal at the outlet of the tuyere combustion zone. Information-modeling system has been developed. It allows investigation of influence of combined blast characteristics, the properties of coke and coal-dust fuel, the geometric dimensions of tuyeres and other factors on temperature fields and concentrations of components of gas phase in combustion zone. The model also helps to select a rational mode of pulverized coal that will ensure completeness of its combustion in the tuyere combustion zone. Main functions of the program are as follows: representation of results of calculation in form of tables and diagrams, storage of options of basic data in a database and export of results of calculation to Microsoft Excel. Conclusions were made on reduction of combustion temperature in combustion zone and the approach of focus of combustion to the tuyere when pulverized coal was injected. The authors also have established the need to use coals with certain quality characteristics and place where coal dust was introduced into the blast stream.

Reducing Heat Losses Through Blast Furnace Tuyeres

This paper proposes to improve the durability of the heat insulating insert for the air passage of the blast furnace tuyere by applying a slurry coating to the tuyere’s inner surface. In addition, the tuyere installation variant after assembling and exposing it to hydraulic tests is considered, as well as heat loss reduction by attaching refractory fabric to the tuyere nose. The slurry coating applied to the insert’s inner surface has made it more durable by at least 30%. Theoretically, the insert can be made more durable when installed in the air passage after assembling the tuyere and exposing it to hydraulic tests. Studies have shown that the heat losses can be reduced by 10% on average by using refractory siliciferous fabric to ensure the heat insulation of the tuyere nose.

The effect of CaO and MgO on the structure and properties of coal ash in the blast furnace: A molecular dynamics simulation and thermodynamic calculation

The influence of ash composition on the structure and properties of coal ash in the blast furnace was studied using molecular dynamics simulation and thermodynamic calculation. The change in the relative content of CaO and MgO does not cause a large variation of bond length between different ion-oxygen bonds. In the process of increasing the CaO content, more tricluster oxygen are converted into bridge oxygen and non-Bridge oxygen, which reduces the degree of structural complexity of the system. In addition, Ca2+ ions could provide more charge compensation than Mg2+ ions. The ternary phase diagram proved that during the change of relative content of CaO and MgO, there is only a mineral transformation process in which the spinel changes to CaAl2Si2O8. Finally, it is found that in the blast furnace tuyere, the ability of CaO to improve the viscosity of coal ash is obviously better than that of MgO.

Erosion Behavior of Blast Furnace Tuyere

Erosion Behavior of Blast Furnace Tuyere

Decreasing the Heat Losses at the Air Tuyeres in Blast Furnaces

Abstract—In an experiment, insulating inserts are introduced in the blast channel at the air tuyeres of blast furnace 5 at PAO Severstal, so as to decrease the heat losses. The experiment shows that two thirds of the inserts remain intact during tuyere operation. Most often, the tuyeres disintegrate near the gas slot—in particular, between the gas channel and the flange. Insert life may be increased if the slot in the insert and its junction with the gas pipe are protected by means of a thermostable seal. In manufacturing the tuyeres for blast furnaces 1 and 2 at PAO Severstal, the inserts are elongated in the nozzle region, with decrease in the heat losses.