Siemens received the final acceptance certificate from SDI Roanoke for its holistic process model with Lomas offgas monitoring which is reducing conversion costs in its electric steel plant.

In April, U.S. steelmaker, Steel Dynamics Inc. (SDI) of Roanoke, Va., USA, issued the final acceptance certificate for the Simetal EAF Heatopt system installed by Siemens. The newly developed holistic process model combines modern measurement technologies like the Lomas off-gas analyzer with an intelligent control strategy. The system is used to monitor the offgases from an electric arc furnace, and makes an important contribution toward optimizing the process. It has reduced conversion costs by more than $1.50 per ton. This was the first time that a Lomas system had been installed in an electric arc furnace. Siemens is already the market leader for installing this technology in LD steelmaking converters.

Paul Schuler, Melt Shop Manager at SDI Roanoke, said: "The Simetal EAF Heatopt system (Holistic Energy And Transparency Optimizing-System) with the Lomas measurement tool has completely fulfilled our expectations, and in some areas exceeded them. The real-time monitoring and control of the melting process in our 100-ton electric arc furnace has significantly reduced the specific conversion costs. We have also been able to raise productivity and increase operational safety."

The Lomas system and an integrated offgas flow speed meter continuously monitor and analyze the flow of offgas from a furnace. The measured values are fed into the holistic process model and evaluated. This gives the operator’s personnel continual, up-to-date information about the progress of the process in the furnace. The system also generates recommendations for adapting and optimizing the process control. Output deficits arising in the process can be corrected by closed-loop control of the injection of natural gas, oxygen and carbon injection by means of burners and lances. In this way, the consumption of energy and electrodes can be reduced, and the use of oxygen, coal and combustion gas optimized for the process. This increases the efficiency and productivity of the electric arc furnace as well as the output of liquid steel. The Lomas system also increases operational safety by quickly detecting hazardous gas compositions forming during the melting and decarburization processes.