Automation control technology for the world's largest slab caster, at Nucor Hertford, USA

摘要

On October 16th, 2000, the new Danieli Wean United slab caster started operating at Nucor Steel's new plate mill (Hertford, N.C., USA). This caster is equipped with unique mechanical and automation systems, which make it possible to cast 4″ to 6″ thick slabs in widths from 72″ to 123″, and in a wide range of grades such as low, medium and high carbon, alloyed steels, perirectic steel, and structural steels, at speed of 50″/min. In order to achieve the above targets, advanced automation control technologies were used by Danieli Automation, providing: 1. Coordination of the caster activities with both the upstream processes (EAF, LF) and the downstream processes (Reheating Furnace, Mill). Sequences, heats, siabs production and pacing requirements are generated in order to optimize the overall plant production. 2. Management of the casting practices for each step such as ladle arrival, treatment at the caster, start of casting and end of casting. 3. LPC~R, Liquid Pool Control calculation model that estimates parameters for the liquid cone, the mushy section and the solidified thickness. 4. Optimization of the slab cutting, with increased material yields. 5. QUART~R, Quality Control System that tracks and certifies any slice of the slabs produced. 6. Optimization of the usage of moulds and tundishes. 7. Generation of production and quality reports. Optimum performance of the equipment and support to the operators is guaranteed by the following functions: 1. Automatic tundish level control. 2. Mould level control with auto-start. 3. Hydraulic mould oscillation with "Synchro-parallel" control. 4. Dynamic spray cooling control. 5. Dynamic soft reduction control. 6. Breakout and sticking prevention. 7. Automatic mould width adjustment. 8. "Easy set-up" function. 9. "Ready to cast" support. 10. "Ghost casting " simulation. 11. Automatic kick-in of emergency systems in case of failures. As a result of the above, each phase of the process is automatically controlled and continuously monitored, thus making the treatment repeatable, and achieving prime quality in the finished products. This paper describes how this project was carried out, with particular focus on the architecture of the automation system, the principles of the process modelling, the control strategy used, and the results achieved.