Continuous casting — Modern techniques to solve an old industrial problem
Most of the steel we use every day comes from continuous casting, over 90%. This is a process which was industrially introduced in the 1950s, but the first patents are hundred years older. Before continuous casting, the steel was poured into closed molds to form ingots. With the development of continuous caster became possible to produce continuous billet, blooms or slabs. It allowed to have very long pieces, with better quality, much faster. The technology has improved since its invention and nowadays these casters can produce up to 10 meters of steel per minute.
Based in Friuli Venezia Giulia, there is a worldwide leader in the production of continuous caster, Danieli & C. Officine Meccaniche SpA. According to the SISSA mathLab DNA, the company came up with a bold challenge, and together we work to find the solution. This is also an international cooperation with the ITMATI of Santiago de Compostela (Spain) and one of the European Union funded projects of ROMSOC, a Marie Skłodowska-Curie project that involves universities and companies all over Europe to work together on challenging industrial problems as this one.
The problem proposed by Danieli is related to the control of continuous casters. As they go faster and faster, to control the quality of the product becomes harder and harder. The main problems arise at the mold. There, the steel begins its solidification and strong heat fluxes are involved. The quick solidification of the steel can lead to several issues, form the steel sticking to the mold to surface imperfections. Then, it is essential to properly control the process and to be able to detect malfunctions.
Until now, steel makers used thermocouples to measure the temperature at some points in the mold. However, the coarse temperature maps provided by the measurements are not sufficient for a proper understanding of the behaviour of the mold. In fact, we need to information on what is happening at the mold-steel interface. In particular in this research, we have been focusing on the heat flux at the interface.
The objective of my research is then to develop a method for estimating the heat flux at the mold-steel interface based on the measurements of the thermocouples made inside the mold domain. Moreover, this has to be done in real time since we want to detect a casting problem as soon as it starts.
In general, these kind of problems are called inverse problems. In fact, we are given the state (temperature) in the interior of our domain and we want to estimate the boundary condition. While in a classical “direct” problem, the boundary conditions are given and we want to compute the state in our domain.
As you may know, it ain’t easy to work with inverse problems which, by the way, are ill-posed. Several techniques have been developed for solving this kind of problems. However they are generally computationally expensive. Here is where Model Order Reduction comes into the picture. In this project, we have been working on model order reduction techniques to speed up the solution of this inverse heat transfer problem allowing the real time estimation of the mold-steel heat flux.
Science transfer can be a key driver for both research and industry. This is only one example that working on a real world application can lead to improvements in both fields, generating research results and companies advantages. In the near future, this process will probably be the game changer to face the industrial revolution that is undergoing worldwide. Together we can!
References
[1] U. E. Morelli, P. Barral, P. Quintela, G. Rozza, G. Stabile. A numerical approach for heat flux estimation in thin slabs continuous casting molds using data assimilation. arXiv preprint arXiv:2101.11985
