Siemens VAI Research Articles

ELASTOPLASTIC BEND OF ROUND STEEL BEAM. REPORT 1. SPRINGBACK COEFFICIENT

The round steel beam is widely used in metallurgy, mechanical engineering, construction and is one of the major players in the engine industry. Having the excellent anti-corrosion properties, combined with a remarkable strength, the round steel beam is often indispensable in the production of the various mechanical machines and devices. The cylindrical springs for the railway and motor transport are made from the round beam with the help of the special bending machines. Billets from the round beam are also used in the metallurgy at the manufacture of seamless pipes for the oil and gas industry. The rollers of the sheet-straightening machines and rolling mills in metallurgy have the form of stepped round beam. The steel construction armature is made from the round beam and is close to it by geometric dimensions. The main foreign producers of continuous-casting-billets machines for production of round-cross-section blanks are SMS-Demag (Germany), Danieli (Italy), SMS Concast (Switzerland) and Siemens VAI (Austria). The modern production of round steel beam has place on many Russian metallurgical plants, for example, on JSC “Chusovskoy metallurgical plant”, PJSC “Chelyabinsk metallurgical plant”, JSC “Volzhsky pipe plant”, OJSC “Nizhneserginsky metizno-metallurgical plant”, JSC “Chepetsky mechanical plant”, PJSC “Seversky pipe plant” and PJSC “Taganrog metallurgical plant”. In manufacture of articles from round beam and under their exploitation, they often have an elastic or elastoplastic deformation of bending or have a complex deformation of torsion with bending. The analytical method for determining residual curvature of round steel beam under elastoplastic bend is proposed in this paper. The calculations allow us to determine residual curvature of round beam after bending and the bending moments of beam’s cross section at bending depending on the beam’ radius, elastic modulus, yield stress and hardening modulus of beam’s metal. The research results can be widely used at engineering and metallurgical plants.

Elastoplastic Flexure of Round Steel Beams. 1. Springback Coefficient

Round steel beams are widely used in metallurgy, manufacturing, and construction. It is often irreplaceable in the production of machines and mechanical equipment on account of its excellent corrosion resistance and remarkable strength. Cylindrical springs for road and railroad vehicles are manufactured from round beams by means of special bending machines. Round beams also serve as blanks in the production of seamless pipe for the oil and gas industry. Stepped round beams are used as rollers in rolling and straightening mills. Steel rebar is manufactured from round beams of similar size. Outside Russia, the main producers of continuous-casting machines for the production of round billet are SMS Demag (Germany), Danieli (Italy), SMS Concast (Switzerland), and Siemens VAI (Austria). Russian producers include AO Chusovskii Metallurgicheskii Zavod, PAO Chelyabinskii Metallurgicheskii Kombinat, AO Volzhskii Trunbnyi Zavod, OAO Nizhneserginskii Metizno-Metallurgicheskii Zavod, AO Chepetskii Mekhanicheskii Zavod, PAO Severskii Trubnyi Zavod, and PAO Taganrogskii Metallurgicheskii Zavod. In the manufacture of parts from round beams and their use, they often experience elastic or elastoplastic flexure or complex torsion and flexure. In the present work, we propose an analytical method of calculating the residual curvature of round steel beams in elastoplastic flexure. In the calculations, the residual curvature of the round beam after flexure and the bending moments of the beam cross section in flexure are determined as a function of the beam radius, the Young’s modulus, the yield point, and the hardening modulus of the steel. The results may be widely used at manufacturing and metallurgical plants.

Dynaphase: Online Calculation of Thermodynamic Properties during Continuous Casting

The Siemens VAI software model DynaPhase calculates thermodynamic properties depending on the chemical analysis of steel. It can be used online together with Siemens VAI’s secondary cooling model Dynacs 3D, which is a unique feature. Offline it can be used to investigate the thermodynamic properties of steel grades and therefore supports the development of new grades. The core of DynaPhase is a substitutional solution model for the Gibbs free energy for calculating multi-component phase diagrams. The parameters of this model are determined by employing the CALPHAD approach. This model is combined with a microsegregation model to account for the interdendritic solidification process. New differential scanning calometry measurements of the Department of Metallurgy at the Mining University of Leoben have been used to extend the DynaPhase database for high Al or Si concentrations. This paper shows how important correct thermodynamic properties calculations with DynaPhase are, for controlling the secondary cooling system in continuous casting.

Разработка усовершенствованной системы автоматического управления положением электродов дуговых сталеплавильных печей и агрегатов ковш-печь

The paper deals with consideration of the improved mathematical model of the automatic electrodes’ position control system of electric arc furnaces (EAF) and ladle furnaces (LF). As a simplification the mathematical model has been presented in one-phase form. It consists of: 1) model of furnace’s electric circuit with non-linear equation Cassie describes instantaneous admittance of electric arcs, 2) model of hydraulic electric drives with servovalves which have non-linear regulation characteristic, 3) adaptive non-linear impedance regulator. Comparison between traditional structures of the non-linear impedance regulators using inside electrodes position control systems “ARCOS” (Siemens VAI) and “HI-REG” (Danieli) and improved regulator in new control system “RADUGA PK” is considered.

Modernizing steel-smelting equipment

The development and operation of the steel-smelting system at AO Liepayas Metalurgs is considered. The system consists of a 100-t arc furnace (STG Group), with a lateral scrap heater (COSS system, Fuchs Technology GmbH), a ladle-furnace unit (STG Group), and a continuous-casting machine introduced in 2006 (Siemens VAI).

Trends in the Steel Industry: Innovative Solutions to Drive Sustainability

Megatrends will shape the future. Climate change, urbanization, demographic change and globalization challenge all industries. The key to success will be the speed how the steel industry adapts to this fast changing environment. In order to sustainably maintain a competitive position, steel producers must focus on innovative technological solutions which provide advantages regarding costs, quality, production and maintenance. Siemens VAI Metals Technologies therefore focuses on sustainability in their research and development activities which provide benefits to steel producers now and in future. The biggest growth rates can be expected in India in the years to come. However, tightened competition must be expected, especially from China and other high developed steel producing countries. In recent years Siemens VAI Metals Technologies has increased its numbers of innovations with focus on flexibility regarding raw material quality, energy saving and recovery solutions, operational enhancements, reduction of process steps by compact plant designs and linking of processes, productivity and quality gains and maintenance improvements. An outlook into the future is provided in brief showing some future scenarios derived from an internal study called Pictures of the Future, made by Siemens VAI Metals Technologies recently.

Performance comparison of a blast furnace gravity dust-catcher vs. tangential triple inlet gas separation cyclone using computational fluid dynamics

A gravity dust-catcher is a high tonnage device that is widely used to separate a mixture of dusts from blast furnace (BF) top gas flow. Dusts include limestone, iron ore and coke/coal. For decades, the gravity dust-catcher has been the equipment of choice to clean blast furnace top gas generated from the energy intensive iron making process. However, in recent years there has been an increase in demand for gas separation cyclones in place of the gravity dust-catcher due to the substantially higher particle separation efficiencies that can be achieved. Yet, reliability still remains an issue due to higher maintenance costs associated with regular repair of refractory lining within the cyclone.The effect on particle separation efficiency is analysed as a result of these two different dust separation approaches. Using a modified gravity dust-catcher design, together with a new design developed by Siemens VAI for a triple inlet gas separation cyclone, computational fluid dynamics (CFD) simulations are used to predict the potential performance of the two types of equipment. It is concluded that whilst the patented gravity dust-catcher substantially increases the particle separation efficiency over existing dust-catcher designs, the gas cyclone is some 48% more efficient. The modified dust-catcher design may however provide an effective low cost alternative to a gas separation cyclone if it can be retro-fitted to existing operations.

The Flash-Reactor as Special Melting Unit for Powdery Materials in DSG (Dry Slag Granulation) Application

The Flash-Reactor is a new facility for recycling of zinc containing dusts from the steel industry. Therefore the facility must have the capabilities to process a wide range of dusts with varying zinc content. The Flash-Reactor pilot plant was successfully set into operation at the Montanuniversitat in Leoben in 2010 and another series of experiments was conducted in February 2011. Because of the various operating conditions adjustable in the facility and the compact design the Flash-Reactor can be used as a special melting unit for powdery goods. Siemens VAI wants to build a pilot plant for dry slag granulation for testing the possibility of integrated heat recovery, needing small amounts of liquid slag for the test performance. This is where the Flash-Reactor enters the project as upstream melting unit. Heat recovery during slag granulation provides energy recovery of 20 MWth or 6 MWel regarded to a slag mass flow of 1 t/min. Tests in the beginning of the last decade have proven the functionality of the compact dry granulation process, industrial application has failed due to uncertain economic lookout for the steel industry in that time.

Next Generation Mold Level Control: Development of LevCon 2.0

Siemens VAI develops the next generation of the successful mold level controller LevCon. The new controller uses the most modern control principles from optimal control theory while being robust enough to operate in the difficult conditions of a steel work. One prerequisite for the application of modern control theory is a good mathematical model of the process. In the past, the models used for mold level control design were quite simple, neglecting some of the important limiting factors such as surface resonance waves of the mold level. For the derivation of a resonance surface wave model, extensive water model trials have been carried out. With the help of the plant model, modern control theory is applied and a mathematically optimal controller feedback is designed. It offers an increased disturbance rejection compared to earlier algorithms, which is significantly reducing the mold level deviation due to disturbances as, e.g., unclogging events. However, there are still disturbances that cannot be eliminated completely, like mold level hunting caused by instationary bulging. In the past, mold level hunting was reported to be a very slow disturbance with a wavelength of approximately one roller pitch and a frequency below 0.1 Hz. During the development work, it turned out that also higher harmonics of this base frequency exist with wavelengths of 1/2, 1/3, up to 1/7 of the roller pitch. These high frequency fluctuations cannot be eliminated by feedback control only. However, an additional feed-forward loop which utilizes the withdrawal drives power for direct compensation of the mold level hunting steel flow is developed. With this approach, it is possible to reduce even fast mold level hunting.

Investigation of Spray Cooling Heat Transfer for Continuous Slab Casting

The spray cooling technology is a key technology in the continuous casting process, which has a significant influence on the product quality. In order to ensure high quality standards at different operating conditions, modern continuous casting machines provide the possibility to vary the cooling with respect to intensity, width, stand off distances, etc. For design purposes, numerical simulation is used to calculate the feasible operating range of the caster. During casting operation, an online thermal tracking model, e.g., Dynacs, computes the set points of the cooling intensity depending on the actual casting conditions. Both tools use mathematical models which require precise information about the cooling characteristics of spray nozzles. The subject of the present work is the modeling of the convective heat transfer due to spray cooling using flat spray air-mist nozzles, which are widely used in slab casting machines. Measurements of the spray pattern and air/water flows were carried out on a spray test stand in order to investigate the profiles of the water flux at different air/water pressures and different distances from the nozzle tip to the surface. The air-to-water ratio was chosen according to the well-proven Siemens VAI air pressure control curve. The heat transfer coefficients due to spray cooling were measured using an experimental stand which allows spray cooling experiments up to a surface temperature of 1250°C. Based on the obtained experimental data a heat transfer correlation for air-mist sprays is developed to describe the effect of the different operating conditions on the spray cooling heat transfer coefficient. The correlation shows good agreement between the heat transfer coefficient profiles from prediction and experiment.

Arvedi ESP first thin slab endless casting and rolling results

The Italian steel producer Acciaieria Arvedi SpA operates a minimill for flat rolled products with a single casting line (maximum width, 1300 mm) in Cremona, Italy, with an annual output of 1·3 million tonnes per year of flat products using inline strip production (ISP) technology, patented by Arvedi. Following this positive experience with its continuous thin slab casting and rolling process, improved in several stages over the years and resulting in a stable production unit of high quality hot rolled strip, it was decided to invest in a new line adopting endless strip production (ESP) technology, also patented by Arvedi, a direct evolution of ISP. Owing to its highly compact layout with a total length of ∼180 m, lower investment costs are incurred for an Arvedi ESP line compared with conventional thin slab casting and direct rolling plants. Production costs are also noticeably lower than those of other thin slab plants and also of the ISP plant already operating in Cremona. Productivity of the ESP plant, based on a single casting line, will be ∼2 million tonnes per year for the first phase and a possible increase in mass flow from the caster may take capacity up to 3 million tonnes per year. Total energy and water consumption of the Arvedi ESP process is very low compared with that of a conventional casting and rolling process: depending on the final product, energy consumption will be 50–70% lower. Owing to endless rolling operations, the production of strip with uniform and repeatable mechanical properties will be possible along the entire strip width and length and with the line's ability to produce ultrathin hot rolled strip gauges of 0·8 mm (and lower), a subsequent cold rolling process will no longer be necessary for many strip applications. The Arvedi ESP plant is the first example of fully continuous production from liquid steel to hot rolled coil on the downcoiler in 4·5 min, and the Cremona plant is the reference plant (master plant) for sales of future ESP lines. The aim of this presentation is to provide data relative to the new plant and the first production results of the endless casting and rolling line. A contract was signed in 2006 with Siemens VAI as principal process and plant supplier of the new plant, and construction was completed in Cremona in autumn 2008. Start-up was completed in the first half of 2009.

VAiron Sinter – integrated optimisation of ore preparation and sintering

The proven VAiron sinter-process automation system has been enhanced with innovations developed as a result of close collaboration between voestalpine and Siemens VAI. A sophisticated tracking system for bulk materials throughout the ironmaking plant, from ore preparation to the blast furnace, provides the basis for an advanced process optimisation system. Material control in the blending yard and sinter plant has been integrated into a common control model. Diagnosis and control functions have been bundled into a sinter expert system. The chemical properties are stabilised by automatic adaption of the raw material mix. An enhanced burn-through point control system that considers physical and chemical properties has been developed. The waste gas control minimises environmental impact through reduction of SO2 emissions.

Blast furnace optimization, The Next Generation

Previous experience achieved with two of the leading systems, namely the VAIron closed-loop expert system of Siemens VAI Metals Technologies and the VAIF blast furnace expert system are described for several installations. The advantages of both systems have since been combined into an advanced, state-of-the-art system referred to as VAIron–The Next Generation. This paper outlines the structure and highlights of this new expert system.

METALLURGICAL SIMULATION OF THE EAF-PROCESS

The electric arc furnace (EAF) is the starting point in most stainless-steel and in many carbon-steel melt shops. Usually the automation environment consists besides the basic automation system (Level 1) of a real time collection of process related data and some static calculations for the required process-inputs like energy, oxygen, alloys, etc. Siemens VAI developed a dynamic Cyclic Calculation which allows the online-description of the system of steel, slag and scrap during the complete treatment at the EAF. This includes heating and melting of scrap, temperature losses and chemical reactions. The same routines are used for a full cyclic Precalculation of the process before the heat is started, in order to optimize the treatment at the EAF. A Charge Calculation to determine the loading of the scrap-buckets is implemented using a simplex-algorithm.The comprehensive group of Siemens VAI process models is referred to as SteelExpert. This process optimization system (Level 2) has been applied successfully to a wide range of treatment practices like using scrap buckets only, scrap buckets and liquids combined, and also liquid only.

Innovative developments by Siemens VAI in hot-rolling technology

In this paper, Siemens VAI presents its SmartCrown Technology package, which includes innovative solutions for the improvement of dimensional tolerances, of profil and flatness, and for the achievement of high mechanical properties of hot rolled strips. Steel producers can thus benefit from advantages in terms of product quality and cost.