Top gas recycling: This removes the CO2 and recycles the carbon monoxide (CO) back into the blast furnace, potentially using less than half the emissions of today's state-of-the-art blast furnaces.
Top Gas Recycling Blast Furnace
CO and H2 content of the top gas has a potential to act as reducing gas elements, and therefore their re-circulation to the furnace is considered as an effective alternative to improve the blast furnace performance, enhance the utilization of carbon and hydrogen, and reduce the emission of carbon oxides. In Top Gas Recycling Blast Furnace, oxygen is blown into the blast furnace instead of hot air to eliminate N2 in off-gas. Part of the off-gas containing CO and H2 is utilized again as the reducing agent in the blast furnace. CO2 from the off-gas is captured and subsequently stored. Various recycling processes have been suggested, evaluated or practically applied for different objectives. These processes are distinguished by: 1) with or without CO2 removal, 2) with or without preheating, and 3) the position of injection.
Top Gas Recycling
The concept of the Top Gas Recycling Blast Furnace relies on separation of the off gases so that the useful components can be recycled back into the furnace and used as a reducing agent. This would reduce the amount of coke needed in the furnace. In addition, the concept of injecting Oxygen (O2) into the furnace instead of preheated air, removes unwanted Nitrogen (N2) from the gas, facilitating Carbon dioxide(CO2) Capture and Storage (CCS). On the experimental blast furnace, facilities were installed to operate with pure Oxygen(O2) and with re-injection of Carbon monoxide(CO) gas.
Here a gas separation plant will need to be used,