The main functionalities of the software system are process modelling, supervision, control and optimization. The approach illustrated in the figure applies to all metallurgical processes, i.e. starting with the melting of the raw materials in the electric arc furnace (EAF) through all secondary metallurgy processes up to the casting area.
Whenever possible, the system automatically records and tracks process data and events (temperature measurements, material additions, sample analysis) in context of the heat to be produced. Thus, the following information is available to the software user at any times:
- Heats number and grade to be produced in the steel shop.
- Values of all measurements (temperature, oxygen, hydrogen).
- All relevant process data as charts/ diagrams or numeric values.
- Calculated temperatures as well as steel and slag composition.
- Treatment time, delays (power on / power off time).
- Operator instructions and dynamically calculated set-points.
- Warnings and alarms.
- Event logs (send and receive).
Data recording represents a basic functionality of the software system and is realized by the configurable interface manager. The interface, which can be adapted quickly and flexibly, enables process data to be received in real time and set points to be sent to control the metallurgical processes.
Tracking is the process that monitors the state of the entire steelmaking process. The following functionalities are part of this application:
- Overall tracking of the heats to be produces
- Tracking of all material additions
- Tracking of sampling and the chemical analysis of all analysed samples.
- Equipment tracking (ladles, lances, molds, etc.)
- Start and end of the metallurgical processes (chronology9
- Tracking of liquid steel and slag mass (mass balance).
Based on the process data, the process models calculate and predicts the current state of the heat. The current state of a heat is expressed by the chemical composition of the liquid steel and the slag as well as by temperature. The results will be displayed for the operator by means of software cockpits and act as input parameters for control and optimization functions.
Tthe digital model represents the heart of the entire solution. It is based on a fundamental and holistic approach, in which the fundamentals of thermophysics, thermodynamics, reaction kinetics and all energy and mass balances are developed in a general approach for melting and refining.
Workflow and recipe management enables static set-point control for process standardization. The following important information will be provided for the operator:
- Activities (work instructions) to be carried out.
- Treatment goals (duration, target temperatures).
- Target composition for melt and slag.
- Plant-specific setpoints (e.g. blowing pattern including stirring rate, oxygen and inert gas rate and ratio).
Based on the current temperature, composition and mass of the melt and slag as well as the defined target values, the software system dynamically calculates the following set-points:
- Transformer tap set-points for melting (EAF) and heating (LF).
- Set-points for EAF burner and carbon/lime injection.
- Set-points for stirring (gas rate), pressure (RH/VD/VOD) and oxygen blowing (VOD/AOD)
- Alloy additions (cost-optimized).
- Target composition for melt and slag.
- Type and mass of material additions for deoxidation.
- Type and mass of material additions for slag reduction.
- Type and mass of material to adjust the slag conditions (basicity).
All dynamic set-point models take optimization criteria such as economic advantages as well as process related requirements into account. The following optimization criteria are considered in the dedicated metallurgical unit:
- Optimized process gas input (oxygen, nitrogen and aron).
- Optimized material input (scrap, alloying agent, carbon, slag-forming agent).
- Minimizing electrode and energy consumption.
- Optimized dephosphorization and sulphurisation.
- Optimized degassing.
- Optimized decarburization.
- Minimizing the need for reducing agents.
- Minimizing the treatment time.
- Minimization of refractory wear (temperature control).
- Guarantee of process stability.