Improved Recovery of Blast Furnace Gas

A typical BF produces 1200 – 2000 Nm3 of furnace gas per ton of pig iron, containing 20–28% CO and 1–5% H2. The energy content of this gas may equal to an energy export of around 5 GJ/t-pig iron, or approximately 30% of the gross energy consumption in BF. This energy content can be utilized by recovering, cleaning, and storing the BF gas and using it as a fuel or for the generation of electricity. The energy content of the gas varies but is usually low (between 2.7–4.0 MJ/Nm3 depending on CO concentration). Therefore, BF gas is often enriched by coke oven gas or natural gas prior to use.

In cases where the BF is fitted with a two bell charging system, approximately 1.5% of the BF gas is lost every time the furnace is charged. Most of this gas could be recovered by discharging the high pressure gas between the two bells into the low pressure side of the gas collection system just prior to opening the top bell for charging.

Development Status Products
Commercial
iron, steel

Improved Recovery of Blast Furnace GasCosts & Benefits

Parent Process: Blast Furnace System
Energy Savings Potential

Energy savings of 35 MJ/t-HM (Worrell et al, 2010. p. 86) to 66 MJ/t-HM (US EPA, 2010. p.19) are reported. 

CO2 Emission Reduction Potential

US flag Emissions can be reduced by 4.0 Kg CO2/t hot metal.

Costs

EU Flag Retrofit capital costs are $0.47/t-HM have been reported from a plant in Netherlands.  Payback time was estimated to be 2.3 years (US EPA, 2010. p.19).

Improved Recovery of Blast Furnace Gas Publications

Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry

The U.S. Environmental Protection Agency’s (EPA) energy guide, Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry, discusses energy efficiency practices and technologies that can be implemented in iron and steel manufacturing plants. This guide provides current real world examples of iron and steel plants saving energy and reducing cost and carbon dioxide emissions.

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