Requirements for producing steel with lower CO2 emissions are increasing all the time. One way to cut the emissions is to transfer from the Blast Furnace route to the Electric Arc Furnace (EAF) process. The EAF process is effective, but a very energy-intensive way of making steel. There is a lot of room for improvement and optimizing the EAF process could lead to significant cost reductions. This article discusses how to optimize the EAF process and what kind of savings that might lead to!
Steel factories usually control the EAF processes with static methods. These methods are not ideal as there is no exact information about the input material content and material differences between heats. In addition, traditionally there has not been information available about the melting progress due to the extreme conditions inside of the furnace which disables the use of conventional measurement methods. In some cases, process control may be based only on the operator’s knowledge and expertise. What if we could see and measure what happens inside the EAF in real-time?
With real-time melting information, dynamic control of different phases, and optimizing the EAF process becomes possible. For example, the timing of additional scrap charges can be done optimally with this method. The system monitors the status of scrap melting and loads the additional charge exactly when there is enough room in the furnace for the new charge. The furnace power can be controlled optimally when the scrap melting information is available. Adjusting the EAF power based on the melting information will improve the energy efficiency and tap-to-tap times. Also, oxygen and carbon injection timing could benefit from scrap melting information.
How to measure the EAF process in real-time?
The conventional ways to measure the EAFs and the phenomena inside of EAF have had some limitations. For example, off-gas analysis and side panel cooling water analysis suffer from significant delays. It takes time for the gas to travel to the sensors or for the water to heat up in the side panels. Furthermore, it is very difficult to interpret why has the off-gas temperature or side panel temperature increased. These limitations have prevented reliable real-time control – until now.
Optical emission spectrometry (OES) is an analytical technique to break down and examine light emitted from different sources. This method is usually used in detecting different elements in a sample by analyzing the light that they emit when excited (with laser/spark). However, this can be applied to hot metallurgical processes too. For example, EAF emits an excessive amount of light during the heat and the melting progress can be measured by observing the changes in emitted light. This makes real-time measurements possible but gives also other information such as slag composition and temperature.
Luxmet’s optical technology monitors light from the EAF process. This makes it possible to gain real-time measurements from inside the EAF enabling dynamic and automated process control. Luxmet’s solution ArcSpec, a system for measuring and controlling EAF’s, has been proven to significantly improve EAF energy and process efficiency. In addition, the environmental benefits are significant. With our technology is possible to make more steel with fewer emissions!
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