Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - ATHOR (Advanced THermomechanical mOdelling of Refractory linings)

Teaser

Research carried out in the ATHOR project is contributing to and advancing our knowledge of refractory materials. Refractories are heat-resistant materials used as inner linings of high temperature furnaces, reactors and processing units. As the only low cost material able to...

Summary

Research carried out in the ATHOR project is contributing to and advancing our knowledge of refractory materials. Refractories are heat-resistant materials used as inner linings of high temperature furnaces, reactors and processing units. As the only low cost material able to sustain operating conditions at temperatures above 1000°C, refractories are used to contain and process fluids, such as molten metal and glass. Due to the harsh working environment, a constant engineering of refractories is needed, making R+D in the sector vital. Refractories are directly related to the competitiveness of European steel companies and the development of major economic sectors, the impact of any innovation will be felt across Europe.
Through the adaptation and development of the most advanced modelling strategies and experimental technologies, reliable computations and measurements can be achieved at high temperature. Refractory materials used in the lining of a steel ladle, operate in the temperature range 1200-1600oC. ATHOR is targeting the development of high-end engineering technologies in the fields of material’s science and numerical simulations to make a substantial contribution through the design of more robust and reliable refractory linings. Ultimately, the aim is to reduce refractory costs, increase the equipment’s availability and enhance the process control. In addition to meeting our industrial partner’s interests through the reduction in energy use, ATHOR will also contribute to tackling environmental issues.
Refractories used in a steel ladle require a wide range of properties, e.g. high thermal stability, high erosion resistance, high corrosion resistance, penetration resistance, thermomechanical stability, impact resistance, flexibility and creep resistance. The constant reengineering required by the ladle permits analyse of refractories under real world conditions and direct application of the results. The steel ladle was thus chosen as the focus of ATHOR.

Work performed

Development of experimental methods (e.g., strain gauges and contactless optical techniques) in order to collect mechanical data necessary to study refractory materials in service conditions (temperature up to 1500°C, large structures, industrial environment) have been investigated. Improvements to experimental optical methods allow the accurate quantification of low level strain fields and the making of measurements in extreme conditions.
Recent expertise developed by ATHOR partners, in Digital Image Correlation, mark tracking in 2D and stereovision configuration have also been exploited. These technologies are being applied to monitor deformation and temperature of the steel shell of industrial ladle to validate the results of numerical modelling based on mesoscopic characterization. Moreover, bi-axial high temperature testing devices, for a 1m2 masonry wall is being improved.
Selected refractory materials have been characterized at room and elevated temperature, in virgin and corroded state, by conventional and specific experimental techniques. These techniques include; thermal expansion and thermal conductivity, tested by laser flash or hot wire method, Young’s modulus, by ultrasonic echography or RFDA, damage monitoring, by acoustic emission, and the fracture process, by the wedge splitting test. The stress-strain and creep laws have also been determined for tension and compression. This will provide all the experimental results needed for characterisation and understanding of material behaviour at room and elevated temperature.
Dedicated modelling methods and numerical tools to optimize the design of industrial refractory linings have been produced. Different numerical approaches cover the full scale of the thermomechanical refractory lining behaviour. Results predicted via modelling are compared to and validated by experimental results, allowing further refinement of the models.
During the first half of the project one paper has been published and dozens have been presented at conferences around the world. Several dissemination actions have also taken place for the technical community and general public.

Final results

The research is organised into scientific work packages (WP). The WPs are organised so refractory materials are analysed from the micro to the meso scale. WPs 1 and 2 focus on experimental aspects, WP1 develops the measurement tools used so that the accuracy achieved is suitable in extreme environments and WP2 characterises raw materials, refractories and joints to develop a database of material properties. WPs 3 and 4 focus on modelling of industrial systems. WP3, fed with data from WP2, focuses on innovating systems modelling from the microstructure to the industrial scale. Finally, WP4 will incorporate the measurement tools developed in WP1 to help validate the modelling results obtained in WP3. The progress beyond state of the art is detailed below.
WP1 - Improvement of measurement tools
• Experimental protocols for optical techniques have been optimized (100%) and developed for measurements in laboratory furnaces up to 1500°C (100%)
• Improvements have been made for optical measurements taking place in extreme environments: high temperature, thermal gradients, measurement stability of devices, large structure size (100%)
• Due to differences in laboratory and industrial conditions, the effect of environment at each step has been assessed (100%)
• For thermomechanical data interpretations, measured strain fields (obtained by optical techniques) have been correlated to thermal fields (obtained with an infrared camera). Thermocouples with wireless recording were also considered (100%)
• Strain gauges at high temperature have been investigated (100%)
WP2 - Advanced characterization of raw materials,
refractories and joints
• Temperature history for determination of mechanical and thermal properties has been considered (100%)
• Influence of corrosion on thermal and mechanical properties; especially on the RUL (refractoriness under load) and creep in tension and compression, has been studied (60%)
• Fundamental corrosion mechanisms for selected systems, to improve the durability of refractory linings (45%)
• Thermal fatigue behaviour for refractories at room and high temperature (55%)
• Fracture mechanical testing in the SEM for the clarification of fracture mechanisms on the micro-level (50%)
• Inverse evaluation of creep parameters for asymmetric creep out of the Brazilian test by use of FEM-u: DIC coupled with finite-element simulation (60%)
WP3 - Innovative modelling approach from microstructure to industrial scale
• Identification of the best model in the literature for the thermomechanical behaviour of refractories, involving the micro to macro scales (40%)
• Enhancement of the identified model to add the effect of corrosion (40%)
• Identification of the parameters, from raw material to masonry lining, to optimize the design and to improve industrial vessels lifespan (45%)
• Use of innovative modelling, such as DEM, able to deal with multi-fractured media (40%)
WP4 - Advanced measurements for validation
• The ATHORNA device has been developed to carry out advanced measurements in-situ
• Planning of a 3D pilot model of the industrial steel ladle is underway
• Preparation for the use of large-scale testing experiments on conventional masonry, applied to refractory masonry, is ongoing

Website & more info

More info: http://www.etn-athor.eu/.