Title

SUCCESSFUL USE OF FLAMELESS OXYFUEL REHEATING OF SLABS IN A WALKING BEAM FURNACE AT SSAB

SUCCESSFUL USE OF FLAMELESS OXYFUEL REHEATING OF SLABS IN A WALKING BEAM FURNACE AT SSAB

Authorship

Engdahl, Jonas; Lugnet, Anders; Schéele, Joachim von; Nunes, Paulo Rogério

Engdahl, Jonas

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Lugnet, Anders

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Schéele, Joachim von

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Nunes, Paulo Rogério

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DOI

10.5151/2594-5297-17466

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Abstract

The installation in a 300 tonnes/hour walking beam furnace at SSAB uses the REBOX technology, which creates a type of flameless oxyfuel without replacing the existing air-fuel burners. By reducing the air flow and substituting high velocity oxygen injection into the combustion, great benefits can be achieved. Approximately 75% of the oxygen needed for the combustion is supplied with this technique. The fluegas volume is less than 45% that of air-fuel. System start-up took only one day as the REBOX HLL technology continues using the existing air-fuel burners. This eliminates any potential risk relating to implementing the technology because it enables operating technique to be flexible, and optimized in response to fluctuating fuel cost and production requirements. The walking beam furnace had prior to the installation good permance data, including a fuel (oil) rate at 440 kWh/t (1.58 GJ/t). Following is a summary of achieved results from the REBOX HLL installation: emission of NOX can be reduced by 45% (-14% by one zone); fuel consumption can be decreased by 25% (-7% by one zone); leading to the same reductions in SO2 and CO2 emissions, the use of flameless oxyfuel has no negative impact on the surface quality; flameless combustion has a positive impact on the temperature uniformity of the slabs; production throughput can be increased by 15-20% (+6% by one zone); the ideal heating curve suggested by the control system can be achieved more easily and there is less smoke emanating from the furnace, greatly improving the plant environment.

The installation in a 300 tonnes/hour walking beam furnace at SSAB uses the REBOX technology, which creates a type of flameless oxyfuel without replacing the existing air-fuel burners. By reducing the air flow and substituting high velocity oxygen injection into the combustion, great benefits can be achieved. Approximately 75% of the oxygen needed for the combustion is supplied with this technique. The fluegas volume is less than 45% that of air-fuel. System start-up took only one day as the REBOX HLL technology continues using the existing air-fuel burners. This eliminates any potential risk relating to implementing the technology because it enables operating technique to be flexible, and optimized in response to fluctuating fuel cost and production requirements. The walking beam furnace had prior to the installation good permance data, including a fuel (oil) rate at 440 kWh/t (1.58 GJ/t). Following is a summary of achieved results from the REBOX HLL installation: emission of NOX can be reduced by 45% (-14% by one zone); fuel consumption can be decreased by 25% (-7% by one zone); leading to the same reductions in SO2 and CO2 emissions, the use of flameless oxyfuel has no negative impact on the surface quality; flameless combustion has a positive impact on the temperature uniformity of the slabs; production throughput can be increased by 15-20% (+6% by one zone); the ideal heating curve suggested by the control system can be achieved more easily and there is less smoke emanating from the furnace, greatly improving the plant environment.

Keywords

Flameless; Oxyfuel; Reheating; REBOX HLL

Flameless; Oxyfuel; Reheating; REBOX HLL