November 2022 Volume 4

EQUIPMENT & TECHNOLOGY

Figure 2: CO2 reduction as a function of hydrogen volume blended with natural gas.

Therefore, a combustion system decarbonization strategy focused solely on hydrogen fuels can potentially require significant changes to the burner and system design to combat the challenges associated with firing fuels that contain large amounts of hydrogen. The high level of hydrogen content required to achieve significant CO2 reduction, and the design challenges and steep fuel cost associated with hydrogen fuels point to heat recovery with regenerative burners as a logical step on the path towards decarbonization. Overview of Heat Recovery - Regenerative Burners Regenerative burners have played a significant role in the metals industry for many years due to their ability to increase production and lower fuel cost. By reclaiming heat from the furnace exhaust gases and using it to preheat the combustion air, regenerative

burners reduce the amount of fuel needed to heat the product. Regenerative burners operate in pairs, which can be seen in Figure 1. Burner A begins firing while burner B is extracting hot furnace gases through its regenerator. The heat from the furnace gases is stored in the ceramic regenerative media of burner B, and the gases exit the regenerator at a much cooler temperature than the furnace temperature. The burners then switch operation, and burner B, which was previously extracting the furnace gases, now operates in firing mode. Cold combustion air enters through the regenerator of burner B and reclaims the stored heat from the media. This process increases combustion efficiency by up to 45% compared to a conventional cold air combustion system.

Figure 1: Illustration of North American TwinBed®II regenerative burner operation.

Although the historic implementation of regenerative burners has been focused on increasing production and minimizing fuel cost, the current drive towards decarbonization has given regenerative

burners a new purpose in the industry – lowering the carbon footprint of production.

FIA MAGAZINE | NOVEMBER 2022 19