Tap Hole Research Articles

Wear Mechanisms of Carbon-Based Refractory Materials in Silicomanganese Tap Holes—Part I: Equilibrium Calculations and Slag and Refractory Characterization

Silicomanganese (SiMn) as an alloy supplies silicon and manganese to the steelmaking industry. It is produced through carbothermic reduction in a submerged arc furnace. The slag and metal are typically tapped through a single-level tap hole at 50 K (50 °C) below the process temperature of 1873 K to 1923 K (1600 °C to 1650 °C). In one tapblock refractory design configuration, the tap hole is installed as a carbon tapblock and rebuilt during the life of the lining using carbon-based cold ramming paste. The carbon tapblock lasts for a number of years and ramming paste only for months. The purpose of the study presented here was to determine to what extent chemical reactions between carbon-based refractory and slag or metal in the tap hole of a SiMn furnace can contribute to wear of tap-hole refractory. The results of the study are reported in two parts. In Part I, the results of thermodynamic calculations of the potential for chemical reaction between carbon-based refractory material and slag or metal are reported. The results were tested experimentally using pure graphite and synthetic SiMn slag (produced from pure oxides). The paper also reports the composition, microstructure, and phases of industrial SiMn slag, and commercially available carbon block and cold ramming paste refractory materials. These compositions were used in predicted equilibria of refractory–slag reactions. Thermodynamic calculations suggest that reaction between SiMn slag and carbon-based tap-hole refractory is possible, and experiments with nominally pure materials support this. However, practical refractory materials are by no means pure materials, and contain secondary phases and porosity which can be expected to affect reaction with slag. Such reactions are examined in Part II.

Preparation of experimental and numerical research on unsteady cavitating flow around hydrofoil

This paper describes the preparation of the experimental setup and the results of the CFD analysis for the investigation of the unsteady cavitating flow around a prismatic NACA 2412 hydrofoil at different flow conditions. The experimental research is carried out in the cavitation water tunnel located in the Centre of Hydraulic Research in Lutin. The tunnel is integrated into the closed horizontal loop of the hydraulic test rig. The transparent test section provides a full view of the flow around the hydrofoil. The hydrofoil incidence angle is fully adjustable. Two variants of hydrofoil of the same geometry have been designed. One variant is equipped with pressure tap holes for the measurement of the static pressure, and the other variant is covered with a grid of five PVDF films, fully integrated in the hydrofoil. The PVDF films enable to measure the impact forces exerted on the hydrofoil surface by the collapsing cavitation structures. The high-frequency pressure oscillations downstream of the hydrofoil trailing edge are measured using the PVDF hydrophone. The cavitating flow is visualized using two simultaneously operating high-speed cameras providing the top and side views of the flow. A preliminary CFD analysis using the ANSYS CFX package helped to determine the flow regimes for the experimental study. The obtained CFD results agree well with the preliminary measurements.

Pressure on the conical surface of needle valves

Author investigated needle valves in their basic geometry, with conical needle body inserted into the entrance of a sharp-edged cylindrical exit channel. Investigations of two alternative geometries having 90 and 60° included angles were made with scaled-up laboratory model provided with large number of pressure tap holes on the surfaces – together with numerical flowfield computations. Effect of Reynolds number was found generally weak, but variations of the needle lift caused significant changes in the character of the flowfield, with typical three local pressure extremes. A newly observed phenomenon is flow separation from the surface of the cone near its tip.

Properties and Performance of a Mud Gun Mass (Tap Hole Clay) with Respect to the Stable Application of the Product in Blast Furnaces

The new generation of blast furnaces have large volumes, operate at high maximum pressures, and increased blast temperatures. This has resulted in an increase in tapping rate, tapping temperature, and the duration of tapping. This has prompted changes in relation to material and application of refractories in cast house particularly in tap hole clays. The mud gun mass is prone to early erosion and therefore to obtain a trouble free cast, a good and strong tap hole mass with appropriate physical and chemical properties is required. The main physical need is to achieve trouble free tapping of hot metal, and for there to be a constant tap hole length during the tap hole opening operation, which usually takes an hour and ten minutes. Additionally there should be smooth flow of the hot metal and slag. The delivery speed of the hot needs to be as smooth as possible. These are physical requirements to protect the hearth of the blast furnace. This paper deals with the design, performance criteria, property evaluation, and application of a mud gun mass at blast furnace tap hole sites.

Application of Improved Quality Tap Hole Sleeve to Increase Shop Productivity at Rourkela Steel Plant

Rourkela Steel Plant (RSP) has undergone massive modernization to increase production from the existing level of 2.18 Mt to 4.2 Mt crude steel after commissioning of one additional 4060 m3 blast furnace and a third converter of 150 t capacity in Steel Melting Shop-II (SMS-II). The increased volume of quality steel production will largely depend on shop productivity with higher converter availability along with a lower down time for maintenance. The design and refractory quality of the tap hole sleeve for the converter plays an important role in the production of liquid steel and availability of the converter. At RSP, MgO-C quality zonal lining material is manufactured at the in-house brick plant (LDBP) while the tap hole sleeve for the converter is procured from various reputed refractory manufacturers. The life of the sleeve varies between 58 heats and 100 heats with an average of around 70 heats. The frequent change of tap hole sleeves not only affects converter lining life due to thermal spalling but also decreases availability of the converter. Improved dense quality tap hole sleeves with less material segregation leading to uniform density, chemical composition and strength across the entire tap hole length were procured and tried in converter A of SMS-II. These tap hole sleeves were manufactured in small pieces, pre-assembled to the required size and delivered as single entities of varying denominations. The service life of these tap hole sleeves reached an average level of 93 heats with a peak of 130 heats and the major portion of heats fell within 5–7 min tap duration which helped in less slag carryover and suggestive of reduced consumption of deoxidants.

밀폐형 임펠러의 5축 드릴링 모듈의 개발

An impeller is difficult to machine due to the complex, overlapping and twisted shapes that form the blades of an impeller. Therefore, most CAM software companies have developed a CAM module for manufacturing an impeller in addition to their CAM software. However, it is not easy for inexperienced users to machine impellers. The purpose of this paper is to outline the development of an automatic CAM module for the manufacturing of an impeller (E-ICAM) which is based on visual basic language and which uses a CATIA graphical environment in order to simplify the machining of impellers. The automatic CAM module generates a tool path and proposes the recommended cutting condition according to the stock and tool material. In addition, it includes a post-processor for five-axis control machining. Therefore, a user can easily machine impellers using this automation module. There are two types of impellers: the closed and open types. The closed-type impeller consists of the body and cover parts. To combine these two parts, it is necessary to create tap holes on the shroud of the body. Therefore, in the study, a drilling CAM program for a closed-type impeller is developed and manufactured by creating NC data from the developed drilling program. After manufacturing the test specimen, its compatibility was verified.

Measurements of heat loss and its distribution for the COREX-3000 ironmaking process

The accuracy of the parameters is of great importance in the calculation and simulation of the COREX process. Therefore, it is necessary to measure some parameters, especially the heat loss and its distribution, which have not been reported before. Based on the characteristics of the two sets of the Baosteel COREX-3000 process, a method and standard are established for the heat loss and its distribution. Then the heat loss and distri- bution are calculated based on the measured parameters. The results show that the total heat loss of the two COREX processes is 495.4 MJ/tHM and 413.7 MJ/tHM. The heat loss caused by cooling water accounts for more than 93% of the total heat loss while the heat loss of furnace shells is less than 7%. The main heat loss caused by cooling water takes place at the tap hole zone, which is also the part of the COREX system with the most heat loss Its heat loss is about 30% of the heat loss caused by cooling water and 28% of the total heat loss of the COREX system. The main heat loss of furnace shells takes place at the dome of the melter-gasifier and the reducing gas entrance position of the shaft furnace, where the heat loss accounts for nearly 90% of the heat loss of furnace shells. It is also found that the energy utilization efficiency of the 1# COREX system is much lower than that of the 2# COREX system after comparison.

Mechanical Model and Movement Analysis of Self-Adjusting Bolt in Converter

The movement model of self-adjusting bolt is built in this paper, then the kinematical and mechanical analysis is taken to determine the movement of bolt under the converters working condition.Via the mechanical model analysis of self-adjusting bolts, the load applied to the self-adjusting bolt support including the static weight load of converter and steel liquid, the tilting torque, the dynamic load produced by frequent startup, brake, impact, and the boiling of steel liquid is calculated to determine the distribution of load forcing on the three groups of the self-adjusting bolt. According to the results of stress analysis, the bolt facing tapping hole is the most dangerous when converter tilts 63°. The maximum torque is 281.5101tm.

Failure analysis of a high pressure natural gas pipe under split tee by computer simulations and metallurgical assessment

Crack failure of a 36inch high pressure gas pipe observed during regular inspection of a station has been investigated and the results are presented in this paper. The crack, approximately one meter long, was initiated from a notch inside the hot tapped hole in a pipeline installed about 30years ago. The study was conducted by reviewing the design history and construction data, visual inspection, pipe material characterization, stress and modal analysis by using finite element method. Investigations revealed that the valve, directly connected to the split tee, faced large dynamic periodic forces due to a pressure drop between two pipelines. Metallurgical evaluation of the pipe material by optical microscope and fractography of the crack surface by scanning electron microscopy indicated the presence of elongated inclusions in the steel microstructure together with some indications of fatigue fracture as a poorly formed sawtooth profile. Based on dynamic analysis, it was found that the first mode shape, the maximum displacement and, therefore, the maximum stress were exactly situated within the crack initiation zone. It was concluded that the notch effect in the hot tapped hole, the position of the supports under the split tee and the presence of a large periodic stress were responsible for the initiation and fatigue propagation of the crack in the gas pipe.

Conversion of byproduct carbon obtained from spent pot liner treatment plant of aluminum industries to blast furnace tap hole mass[

The paper describes a method for converting carbon powder obtained as byproduct while decontaminating pot liner by acid treatment route, into blast furnace tap hole mass. Producing an useful industrial product from waste helps in paying back the cost incurred during decontamination process of pot liner and thus improves the overall economics of the process. Blast furnace tap hole mass is a prepared muddy material used to close the tap hole of iron making blast furnace. At iron melting temperature the material carbonizes and becomes hard in order to hold the metallostatic pressure inside blast furnace hearth. Since iron gets oxidized at high temperature this tap hole compound is prepared predominantly from carbonaceous material. Further these carbonaceous materials used needs to be semicrystalline in nature in order to withstand high temperature of the furnace. With rising cost of such carbonaceous material used in tap hole compound, it will be advantageous if a source of cheap carbon material matching the properties of carbon material already in use in the tap hole recipe , could be found in order to bring down cost of production of commercial taphole recipe. The aim of this research was to find such a carbonaceous material from an industrial waste which is difficult to dispose because of its toxic contaminants. Such a material chosen for this work is called SPENT POT LINER of aluminum smelter plant. At present majority of the aluminum smelter plants round the world use Hall-Heraoult's electrolysis process for extracting aluminum metal from molten cryolite. The electrolysis cell used for this purpose constitute large carbon blocks as cathode laid at the bottom and side wall of the cell. These carbon electrodes are known as pot and basically made of anthracite, graphite and binder/electrode pitch. Various manufactures uses 20-30% (1) graphite in their recipe in order to meet electrical properties needed for the pot liner. While graphite is a superior electrical conductor than anthracite (which has similar structure to graphite), 100% graphite is never used in the manufacture of pot as it is soft and can not withstand turbulent molten cryolite contained in the cell. Anthracite on the other hand provides required mechanical property to the finished pot liner. The prefabricated pot liner produces carbon matrix with short range order. Thus prepared pot ultimately contain both crystalline (graphite) and amorphous carbon. During service molten cryolite slowly gets reduced and the sodium fluoride crystal deposits within the fine crevices of pot liner creating defect spots . As time passes, these crystals grow and exert pressure within these crevices resulting in the propagation of crack. As a consequence, with time the pot liner looses its electrical property and ultimately being discarded. These rejected waste pot are called spent pot liners (in short SPL). Spent pot are not only contaminated by fluoride but also by other toxic elements such as cyanides (formed at high temperature reaction with atmospheric nitrogen), alkalis and aluminum. Table-1 below shows typical range of the contaminants in such discarded pot along with concentration of these toxic elements in SPL carbon powder after decontamination with oxidizing acids. In practice suitability of a specific component in a commercial recipe is tested by evaluating some gross property of the modified recipe against the production recipe of the compound. For example, in development of foundry chemicals (like mould coating, tundish cover , hot tops etc) which basically a combination of various components in a formulation , various substitutes are being tried with above procedure of gross evaluation of certain properties of the compound in order to determine its suitability. Similarly in present case of developing suitable substitute of carbonaceous material in commercial tap hole compound recipe, following properties are important in order to determine its suitability. Apparent porosity. This property determines the ease with which gas generated in the tap hole compound during carbonization can escape easily without breaking or decreasing strength of the carbonized tap hole mass. This value is generally maintained in the range 25-35%. a) Bulk density. This is maintained in the range 1.3-1.6 gm/cc in all commercial recipe in order to match with standard pushing length required by the equipment to fill the tap hole.

压裂完井工具高压模拟井筒壁厚的研究

介绍了压裂完井工具高压模拟井筒试验装置的组成和作用。建立了高压模拟井筒的三维仿真模型，并对模拟井筒上的测压孔进行了处理。利用ANSYS软件，对不同壁厚的模拟井筒进行了数值模拟分析。仿真结果表明，当模拟井筒承受105 MPa内压时，测压孔处屈服应力最大，且模拟井筒材料选用35CrMo，壁厚为40 mm时，内径121 mm的模拟井筒可满足设计要求。 Composition and function of high pressure simulation wellbore experimental equipment with crushing com- pletion tools are introduced. A three-dimensional simulation model of high pressure simulation wellbore is established and the pressure tapping hole is also processed. By means of ANSYS software, the numerical simulations of simulation wellbore with different wall thicknesses are carried out. The simulation results show that the yield stress at pressure tapping hole is maximal when the simulation wellbore bears 105 MPa pressure. For 35CrMo material, the simulation wellbore with the internal diameter 121 mm can meet the design requirements, and its wall thickness is 40 mm.

Analysis on the Refractory Erosion of the Electric Arc Furnace and Study on the Measures of Protecting the Furnace Lining

The erosion situation of the refractories of the deep reduction electric arc furnace have been introduced firstly, including the regions such as furnace wall, tapping hole and slag hole, and analyzing on the causes of the erosion shows that high temperature, chemical erosion of oxides in slag, as well as physical scour are the main causes of the serious erosion to the lining. Based on the practical production conditions three solutions are provided including preventing oxidation of metallized pellets, control the temperature and carrying out hot-spray-mending on the furnace.

Experimental and numerical study on slag deposition and growth at the slag tap hole region of Shell gasifier

Cold model experimental and dynamic modeling studies on the slag flow and heat transfer at the slag tap hole region of Shell gasifier have been carried out. The cold model experiment was set up to observe the simulated slag deposition. The dynamic model was proposed to clarify the slag accumulation on the wall of slag screen. The results show that the simulated slag can be broken up to slender liquid filaments by the high-speed swirling gas flow, and a part of the filaments can deposit on the slag screen wall. When the surface temperature is below the critical temperature, the slag is totally solidified to solid slag layer. At equilibrium, a liquid slag layer covers the solid slag layer and its surface temperature is higher than the critical temperature. The solid slag layer thickness increases along the slag flow. In addition, the solid slag thickness can be decreased by increasing the operating load and operating temperature.

New Techniques to Detect the Suitable Time to Close the Tap Hole of a Blast Furnace

AbstractThe closing of a BF tap hole, as a final end to an optimum pig iron and slag tapping contained in the hearth, is an operation that requires the plant operator's complex background to recognize the instant in which the tap hole must be closed; this way avoiding dangerous phenomena relating to whistlinga. In this paper, two systems are described – which may act concurrently – of advisement to the plant's operator in order to warn him of when he must close the tap hole. One of them is based in the processing of the EMF probe signals, which measure the electromotive force between two points of the hearth shell. These probes are welded to the BF shell under study and are located on top and underneath the respective tap hole. The second system uses image treatment of pig iron and slag flow casting coming out of the tap hole in this hostile environment.

Numerical simulation of flow characteristics in settler of flash furnace

A computational fluid dynamics (CFD) simulation was carried out with CFX4.3 to investigate the melt flow and temperature distributions in the settler of a flash furnace. Sixteen cases of one slag tap hole adopted with one matte tap hole (1-to-1) and one slag tap hole adopted with two matte tap holes (1-to-2) operation modes were modelled. The simulation results show that the melt flows are similar in both two operation modes, but evident circulations can be found in the case of the 1-to-2 operation mode. The combination modes of the slag and matte tap holes are found to have a significant effect on the temperature distributions of the melt. The melt temperature is more uniform in the case of the 1-to-2 mode. Selection of a matte tap hole farther away from the inlet is more conducive to achieve a uniform distribution of the melt temperature in the settler in practical tapping operation.

A methodology to investigate the wear of blast furnace hearth carbon refractory lining

AbstractIn this work it is presented a methodology applied by Companhia Siderúrgica Nacional (CSN, Brazil) in order to assess its blast furnace 3 carbon refractory hearth lining conditions. The aim of the investigation was the gathering of critical data base for blast furnace refractories life cycle follow up and eventual repair decision taking.The sample drilling locations were chosen around the tap holes and hearth bottom areas. The advancing drilling depths were based on local temperature profiles. The isotherm limit of 500 °C was elected as a control parameter to assess the critical carbon refractory condition. The guidelines for sampling and testing as well as the results obtained through the physical and chemical characterizations of the cored samples are presented. The condition of the refractory lining is discussed under the light of the different known wear mechanisms of blast furnace hearth carbon refractories.

Experimental Analysis of Strain of Blast Furnaces Shell During the Start up to

Abstract Circumferential BF hearth shell stress was measured during the two blast furnaces blow-in periods. BF1 had the hearth with not developed salamander. It was blew down after reline and few days of full tuyeres operation. BF3 hearth had fully developed salamander after 12 years of operation. Before start up both BF hearths were identical cleaned up 1 m bellow the tap hole elevation. Blow in line on BF1 also BF3 salamander were circumferential trenched out up to the hearth bottom elevation down. Maximal measured BF1 hearth shell tension level reached 100 MPa. 160 MPa was the detected maximal BF3 hearth shell tension. Tension level 100 MPa was detected 6 days after start up on both furnaces, This level stayed identical on BF1 for the next four days but on BF3 tension rose during the next two days period up to level 160 MPa. Maximal pressure started relieve on both furnaces 8 days after start up. Hearth shell stress stabilized on both furnaces on range 30 – 50 MPa when hearth thermocouples readings started stabilize. Data shows significant contribution of hearth refractory to hearth shell stress creation. Melting rate, tuyeres opening strategy, casting schedule can contribute to BF hearth shell stress control during the blow in period.

Main properties for the selection of converter tap-hole materials

In the basic oxygen steelmaking (BOF) steel is tapped through the tap-hole. This piece is made of MgO-C refractories and may contain metallic agents, such as aluminium, silicon, magnesium or a combination of them. There are different alternatives to improve tap hole performance during service, one of them is to improve refractory material properties according to the main stresses and another one is to optimize the design of the inner channel in order to control steel flow patron and pressure distribution to minimize turbulences. The aim of this paper is to evaluate un-used tap-holes from different sources in order to select the adequate quality in terms of operational requirements and to establish a characterization procedure.

Effect of Si-SiC Additives on Properties of Tap Hole Clay

Non-water taphole clay was prepared by using high alumina ((Al2O3)>85%,Particle Size is 3~1, ≤1 mm),coke, clay, kyanite, Ferrosilicon Nitride Powder and Corundum powder, adding more 15% tar as the binder and Si-SiC (0,4%,8%,12%) to replace Ferrosilicon Nitride. Specimens with dimensions of φ50mm × 50mm and 125mm × 25mm × 25mm were prepared under a uniaxial pressure of 5MPa. The microstructure, high temperature bending strength (600oC,800 oC,1000 oC,1200 oC,1400 oC) and apparent porosity and sinter ability of the tap hole clay were studied. The influence of the substitution content of Si-SiC of the tap hole Clay was also investigated. The results showed that the high temperature bending strength of the samples decreased with the increasing of Si-SiC and apparent porosity almost no changing, but it could still met the need of the actual requirement. The Si-SiC substitution content within 5% of the tap hole clay has also good performance. Through the analysis of the microscopic structure of the tap hole clay, the tap hole clay with Si-SiC has good sinter ability.

An examination of suitability of multi-hole pressure probe technique for skin friction measurement in turbulent flow

The problems of misalignment to flow direction and the need to drill a tapping hole on a measurement surface to obtain total and static pressures make the use of Preston probe in skin friction measurement in a turbulent flow a cumbersome task. The suitability of a multi-hole pressure probe in a non-nulling mode to overcome these problems was, therefore, investigated. The near-wall effect on multi-hole pressure probe readings was examined both experimentally and theoretically. The results indicate that the presence of the wall had negligible overall effect. Experiments were carried out in a pipe, on a flat plate and on a swept forward facing step to simulate one-, two-, and three-dimensional turbulent flows. The skin friction coefficient determined using the multi-hole pressure probe was found to have good agreement with published data. Since the technique is based on similarity principle with probe diameter as a characteristic parameter, it is expected that the method would be effective with probe geometries of different sizes provided that they are small enough to be submerged in the boundary layer and that their calibration coefficients are accurately determined.