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Lower energy consumption when gas is used in a new way
Swerim has developed and tested two new methods for improving the use of process gases from the steel industry. Both methods, steam reforming and membrane-based gas separation, can potentially lower overall energy use in steelmills.
Ore-based steelmaking generates large volumes of carbon dioxide (CO2) and carbon monoxide (CO). CO is an energy-rich gas that is used internally in steelmills, principally for preheating, or as fuel for combined heat and power plants for production of electricity and heat for district heating.
2 methods for richer gas
Today, use of this gas in steelworks is limited due to its low energy content. By increasing the energy content, it may be possible to use these gases, for example, as a substitute for oil or fossil reducing agents in the blast furnace.
Swerim has developed and assessed two new methods for increasing the energy content in process gases:
- Converting CO2 to CO via an electrically heated shaft.
- Membrane-based separation of CO2.
100 % increased energy content
The concept shows that it is possible to achieve up to a hundred percent conversion of CO2 to CO, which also means a hundred percent increase in energy content. CO2 separation with the help of zeolite membranes, a technology currently under development, also showed good results for separation from synthesis gas. Both methods have the potential to lower overall steelmill energy consumption.
The energy-rich gas could be used to replace oil and coal. This could reduce energy consumption by up to 2 TWh/ year and CO2 emissions by up to 35 percent, or 2,000 ktonne CO2/year. This reduction corresponds to more than 12,000 round-trip flights between Stockholm Arlanda Airport and Bangkok.
The project has been partly funded by the Swedish Energy Agency.
Photo: Jernkontoret/Stig-Göran Nilsson