Process Control & Automation
As an introduction to expert systems, individual judgment of process conditions and required actions receive support by rule-based decision systems with an incorporated, standardized operation strategy that has been jointly elaborated for the individual furnace. By model-supported analysis of the operational condition, an early detection of undesired deviations allows for safely going closer to the operational limits. By this, improved results regarding blast furnace performance, fuel rates and operational stability can be achieved. This paper shows practical examples of critical operational conditions of the blast furnace and the corrective actions automatically suggested and executed by the expert system.
In the production of flat-rolled steel sheet, surface quality is a key factor in distinguishing steel products between automotive and other applications. Due to the growth of market competitiveness, which requires the product to be checked on-line in terms of defect detection and classification, steel producers have increasingly turned to the use of commercially available automated surface inspection systems (ASIS) to aid in the detection and classification of surface defects. High defect detection and classification performance of an ASIS is an important prerequisite for efficient use of ASIS for improved surface quality control and assurance. This is especially useful for the hot rolling process since it is the earlier rolling process, and ASIS results with good classification performance could be used to avoid defect crisis and reduce costs in the following processes. This paper focuses on classification performance optimization using ArcelorMittal Cleveland’s hot strip mill ASIS as an example.
By means of the theorem of three moments and the empirical theory of elastoplasticity, a real-time program for leveling hot-rolled strip has been developed by Nucor Steel Tuscaloosa Inc. (NSTI). Development work was composed of establishing an algorithm for the leveling process and programming it using C#. The application features a graphical user interface with flight load prediction, roll gap setting and shape correction. In addition, the application links to a database for existing mechanical properties to further the accuracy of the algorithm. The application has been installed to provide successful production setups, control shape quality and prevent equipment failure for the levelers at NSTI.
Reheating furnaces are used by steel plants for the hot rolling process, in which steel slabs (or billets or blooms) are reheated to a target rolling temperature. The reheating furnace heats slabs to high temperatures in a highly oxidizing environment, which results in the formation of iron oxide scale on the slab surface. Scale formation poses an ongoing material (and economic) loss to industry and should be minimized where feasible. The kinetics of scale growth are complex and are still not fully understood. Previous studies that modeled scale formation with mathematical methods have been limited to simple case studies. In this study, computational fluid dynamics was used to simulate slab reheating furnace operations and to investigate complicated physical phenomenon. In this paper, a new numerical method has been developed to model the growth of scale under varying conditions/characteristics including temperature, gas atmosphere composition and steel grade.
To ensure continued reliable operation, something had to be done about Galvanizing Line No. 1 at Steel Dynamics Inc.’s plant in Butler, Ind., USA. Computers, programmable logic controllers and I/Os were 20 years old, and obviously needed replacement. Not so obvious was what to do with the DC motors that still had useful life remaining. The solution was a dual-purpose drive suitable for controlling both AC and DC motors while providing an upgrade path to all AC. AC-DC converters operating at unity power factor relieved the plant of significant kVA loading with lower-cost operation. This paper will review the successful upgrading of Galvanizing Line No. 1.
The Control of Hazardous Energy (lockout-tagout-tryout) is an important U.S. Occupational Safety and Health Administration (OSHA) compliance program in the steel industry, designed to ensure that dangerous energy sources are properly neutralized before performing maintenance, in order to prevent serious injury or death. This paper describes the development of an interactive 3D software with a virtual environment and hands-on experience, where employees follow OSHA guidelines and complete a lockout-tagout procedure. The software teaches workplace procedures and intuitively allows monitoring of how behavior impacts personal safety.