Top Gas Recycling Blast Furnace Process Mar09

Top Gas Recycling Blast Furnace Process...

Top Gas Recycling Blast Furnace Process In the area of production of hot metal (HM) by blast furnace (BF), the most promising technology to significantly reduce the CO2 (carbon di-oxide) emission is recycling of CO (carbon mono oxide) and H2 (hydrogen) from the gas leaving the BF top. CO and H2 content of the top BF gas has a potential to act as reducing gas elements, and hence their recirculation to the BF is considered as an effective alternative to improve the BF performance, enhance the utilization of C (carbon) and H2, and reduce the emission of CO2. This ‘top gas recycling’ (TGR) technology is mainly based on lowering the usage of fossil C (coke and coal) with the re-usage of the reducing agents (CO and H2), after the removal of the CO2 from the top BF gas. This leads to lower the energy requirements. Because of the advantages of high productivity, high PCI (pulverized coal injection) rate, low fuel rate, and low CO2 emission etc., the TGR-BF process is considered to be one of the promising ironmaking processes in future. In TGR-BF, oxygen (O2) is blown into the BF instead of hot air to eliminate nitrogen (N2) in the top BF gas. Part of the top BF gas containing CO and H2 is utilized again as the reducing agent in the BF. CO2 from the BF top gas is captured and then stored. Several recycling processes have been suggested, evaluated or practically applied for different objectives. These processes are distinguished by (i) with or without CO2 removal, (ii) with or without preheating, and (iii) the position of injection. The concept of the TGR-BF (Fig 1) involves many technologies which include (i) injection of reducing top BF gas components CO and H2 in the...

Ironmaking by Blast Furnace and Carbon di Oxide Emissions Jan14

Ironmaking by Blast Furnace and Carbon di Oxide Emissions...

Ironmaking by Blast Furnace and Carbon di Oxide Emissions It is widely recognised that carbon di-oxide (CO2) in the atmosphere is the main component influencing global warming through the green-house effect. Since 1896 the concentration of CO2 in the atmosphere has increased by 25 %. The iron and steel industry is known as an energy intensive industry and as a significant emitter of CO2. Hence, climate change is identified by the iron and steel industry as a major environmental challenge. Long before the findings of the Inter-governmental Panel on Climate Change in 2007, major producers of iron and steel recognized that long term solutions are needed to tackle the CO2 emissions from the iron and steel industry. Therefore, the iron and steel industry has been highly proactive in improving energy consumption and reducing greenhouse gas (GHG) emissions. In the present environment of the climate change, within the iron and steel industry, there is a constant drive to reduce energy costs, reduce emissions and ensure maximum waste energy re-use. In the traditional processes for producing iron and steel, emission of CO2 is inevitable, especially for the blast furnace (BF) process, which requires carbon (C) as a fuel and reducing agent to convert iron oxide to the metallic state, and hence is the main process for the generation of CO2 in an integrated iron and steel plant. Climate policy is in fact, an important driver for further development of the ironmaking technology by BF. Critically, amongst the challenges facing the BF operation is decarbonization. Significant steps have been made by the iron and steel industry to increase the thermal efficiency of the BF operation, but ultimately there is a hard limit in decarbonization, associated with the need for C as a chemical reductant. Since the 1950s,...