Flexibility in EAF Operations at Nucor Steel-Arkansas with DRI

摘要

Nucor Steel-Arkansas NSA has two 150 ton DC electric arc furnaces (EAF) that operate in a range of 500 to 950 volts and 140 KA. In early 2012 NSA started increasing the DRI percentage in the scrap mix from 12% to as much as 50%, replacing mainly Pig Iron. The main challenge was to adapt to the continuous changes in our scrap mix, for the main purpose of when to efficiently start feeding DRI and at what flow rate. AMI GE's Smart Furnace Technology for DC furnaces was installed to help optimize EAF operations. The Smart Furnace control system includes: Smart arc (power control), Burner control, and DRI control. Before the Smart Furnace was installed, there was a large variation between furnace operator's performances; including but not limited to average voltages, electricity usage, power on times and consistent slag chemistry. These variations were highly dependent on the DRI profiles defined by each operator. The Smart Furnace System was installed to analyze inputs and to "learn" the best operating practices. This technology helped to optimize furnace operations and allowed the operator to adapt quicker to changes in the scrap market. The system was first installed on EAF #2 in November of 2011 and then in EAF #lin August of 2013. Results indicate flexibility while optimizing performance when using varying levels of DRI.