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Less energy consumption and more safety due to Chameleon

More sustainable production is a current challenge in the steel industry, as it is in many industries. Steel producers strive to use less energy and reduce emissions to protect the environment, counteract climate change and ultimately cut costs. An important process variable in steel production is the temperature of the liquid steel in the so-called Electric Arc Furnace (EAF).

While a Basic Oxygen Furnace (BOF) uses iron ore and coal, an Electric Arc Furnace (EAF) produces steel from recycled steel scrap. Since no additional coal is used in the EAF process, the CO2 emissions are much lower compared to the BOF.

The more accurate and reliable the temperature measurement, the better the optimum time for tapping can be predicted, which in turn has an impact on the steel quality. Furthermore, precise control of the final temperature is key to operating the furnace efficiently.

Electric Arc Furnace

Our contribution: Optical measurement to determine best timing for tapping

The temperature of the steel bath is usually measured by immersing lances with disposable probes into the liquid steel. Such an immersion measurement process with a thermocouple takes two to three minutes. It is done at the slagdoor side – but the heat distribution in an EAF is not homogenous: the coldest spot in the furnace is usually at the eccentric bottom tap-hole (EBT).

Different Components of Chameleon
Chameleon components

Since the temperature at the EBT tapping side is quite unknown, the furnace is overheated to avoid problems with tapping blockages, resulting in spending too much energy, CO2 and time. While tapping too early could result in process blockages due to unmelted scrap. With Chameleon, experts at Heraeus Electro-Nite have developed an innovative system that allows to measure at the right place which is the EBT.

Illustration: Measurement of the thermal radiation
Thermal radiation

Faster response due to reliable data

Chameleon is a novel application of optical fiber-based measuring, delivering accurate temperature readings in seconds. It is run remotely from a control room – an advantage in terms of safety, as no operator needs to come close to the furnace.

In sequence mode, the system decides independently when to initiate the next measurement. A Chameleon measurement takes only ten seconds. Due to instant data availability the temperature can be observed almost in real time. A semi-continuous temperature profile helps to define the desired end point of each melting cycle, meaning the operator can reliably tap at the optimal time - not too early, not too fast.

Depiciton of Results
Measurement result

Chameleon allows maximum process control for an optimal temperature of the liquid steel during the operation of electric furnaces. The power-on time of the EAF can be optimized and overheating can be reduced. This results in saving energy, which in turn means less CO2 emissions. Chameleon thus contributes to a “greener” steel production.