Categories: Steel
Published 14 Sep 2023

Electrification of heating processes is one of the key strategies on the route to greener steel production. But converting from gas to electricity is not entirely without challenges. Dilip Chandrasekaran, Kanthal Business Development Manager, shares his hot take on how best to make the switch.

Although there are still many misconceptions about the benefits of electric heating, more and more steel producers are becoming aware of the advantages of going electric. From reducing CO2 emissions, to improving both efficiency and the workplace environment, electric heating comes with plenty of benefits and few drawbacks.

Once a steel company has the willingness to switch to electric, we can help out with the rest.

“Some steel companies may still be concerned that electric elements don’t have the absolute power or power density to get the job done,” says Dilip Chandrasekaran, Kanthal Business Development Manager. “But, these days, most steel companies are aware that electric heating elements are not only powerful enough but also improve thermal efficiency and the work environment, while contributing to quality improvements.

“Once a steel company has the willingness to switch to electric, we can help out with the rest.”

Choosing what processes to electrify

CaptionDilip Chandrasekaran, Kanthal Business Development Manager.For some, the greatest obstacle on the road to making the switch may simply be knowing where to start.

Chandrasekaran explains that Kanthal has identified three heating processes in downstream steel production that are among the easiest to convert to electric – the Continuous Annealing Line (CAL), Continuous Galvanizing Line (CGL), and Roller Hearth Furnaces.

“You can retrofit an existing furnace simply by replacing the existing gas burners in the furnace with tubes and electric heating elements, and making a few small modifications,” says Chandrasekaran.

Making adjustments for a new heat source

He highlights that the most straightforward process to convert is a gas-fired furnace that uses a technology called single-ended recuperative burner systems (SER). Here, it is possible to install bayonet or electric cartridge heaters, such as Tubothal®, either in the existing radiant tubes or by replacing both tubes and elements.

“No changes need to be made to the interior of the furnace or the furnace insulation,” continues Chandrasekaran.

When it comes to converting furnaces that use gas burners and U, W, P or double P-type gas-fired radiation tubes, things get a bit more complicated. Chandrasekaran explains that this technology may require the support and insulation in the furnace wall to be modified.

Both cases requires some work to be done to the outside of the furnace, where existing gas lines and exhaust pipes need to be removed and replaced with cabling for feeding the electric heating elements.

Redefining the electric power

Another factor that can prove tricky is redefining the total electric power.

“Accurately defining the efficiency of the electric solution versus the efficiency of the gas solution isn’t easy,” admits Chandrasekaran, adding that steel companies tend to have limited knowledge of the impact that changes in heat transfer and efficiency may have on the properties of their end product.

While thermal engineering calculations can be made, these will only provide an approximate picture of the outcome.

“The only way to obtain a reliable prediction is through testing – for example, by carrying out a stepwise conversion of parts of a heating zone or converting it zone by zone. Additionally, the end user must ensure that sufficient electrical power is available, and that the factory has the necessary infrastructure in place for distribution to the electrically heated furnaces,” says Chandrasekaran.

Furthermore, the power control system will need to be redesigned.

“With a gas furnace the control system can be quite simple, but running an electrical solution could be more complex, you need to understand how to control and regulate the power on the elements to avoid overheating and maximizing the lifetime of the elements,” Chandrasekaran adds. “However, the upside is that the temperature control in the furnace will be significantly more accurate when using electric heaters.”

Securing access to renewable electricity

Electric heating provides the opportunity to fully eliminate CO2 emissions. For this to happen, access to renewable electricity is a must, but there’s no quick-fix solution. The volume available and its cost varies enormously from country to country. The good news is that most governments are working to solve the problem.

In the meantime, Chandrasekaran believes it is only a matter of time before switching away from fossil-based power becomes less of a choice and more of an imperative.

“All over the world, governments are requiring companies to move away from fossil fuels and most major steelmakers all looking for ways reduce their emissions,” he says. “Only they can make the decision but, once they do, we have the expertise and experience to make the switch to electric happen.”