EcoLowNOx: Auxiliary Combustion System for Efficient Combustion with Low-NOx Emissions for Foundation Industries

Nitrogen oxides (NOx) are a group of gases mainly formed during fossil fuel combustion. A more potent greenhouse gas than carbon dioxide and a contributor to acid rain, governments worldwide – including the UK – are increasingly placing restrictions on NOx emissions.

The high volumes of gas and extreme heat of steel manufacturing furnaces mean there is an urgent need to develop technology that reduces NOx emissions to meet ever-tightening regulatory requirements. Industrial combustion systems specialists Global Combustion Systems (GCS) aims to provide a solution with ‘Auxiliary Injection’ technology designed specifically for the steel industry.

“Since 2016, our Auxiliary Injection system, which has the potential to reduce NOx by 80%, has been made operational at several glass plants in Europe. This patented technology was developed by GCS, together with the University of South Wales and ENGIE,” explains Iain Shoveller, Director of GCS.

“In this process, a proportion of the fuel is injected into the furnace so that it mixes with the recirculating combustion products before mixing with the mainstream combustion air. This means combustion occurs at a lower rate in a high proportion of inert gases. Hence, the flame temperature is low and, therefore, NOx formation is reduced compared with conventional firing.”

With funding from the Transforming Foundation Industries Challenge, GCS investigated whether its glass Auxiliary Injection system could be adapted and transferred to meet the needs of the steel industry.

“The project demonstrated that our Auxiliary Injection technology could reduce NOx with the type of burner used in steel furnaces.”

Landscape of the steelmaking site at Port Talbot, South Wales

Using the Glass Futures combustion-test-bed furnace, the project team assessed the performance of the technology in a range of scenarios designed to simulate a steel furnace. Meanwhile, a team at the University of South Wales fed data from industry partners Tata Steel and Liberty Steel UK into computer models to better understand the transfer of GCS’s technology into steel applications and quantify potential benefits.

“The project demonstrated that our Auxiliary Injection technology could reduce NOx with the type of burners used in steel furnaces. The modelling also suggests the technology has the potential to save fuel, too,” says Shoveller.

Importantly, GCS’s system can be fitted retrospectively. “Another technology exists to reduce NOx, such as Synthetic Catalytic Reduction, but this requires a separate piece of plant to be installed, which takes up a lot of space, and uses Ammonia as a reducing agent, which comes with its own environmental issues. On top of that, it’s very expensive,” explains Shoveller. “Our technology is cheaper, doesn’t require space or extra chemicals, and can be retrofitted on the run to an operating furnace, meaning no downtime for production.”

The next stage is for the technology to be tested in industrial settings. “We also want to explore the impact of hydrogen firing, too,” says Shoveller. “Increasingly, hydrogen is being added to the natural gas network, which has implications for the combustion process, which may further increase the benefits of using auxiliary injection technology in furnaces.”

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