A Numerical Study on the Performance of the H2 Shaft Furnace with Dual-Row Top Gas Recycling

Given the urgent pursuit of carbon neutrality and stringent climate policies, the H2 shaft furnace (H2-SF) is starting to gain widespread attention in the steel industry. In this study, the performance of the H2-SF under operation with a dual-row injection top gas recycling system was investigated by a one-dimensional mathematical model. The potential of microwave heating as a means to supply thermal energy in regions of energy deficit was also assessed briefly. The results showed that for scenarios without microwave heating, increasing the upper-row injection rate can improve the furnace performance, and increasing the distance of the upper-row injection level from the furnace top also has a positive effect. A high microwave heating efficiency is expected in regions above the upper-row injection level. For scenarios with microwave heating, a higher microwave power leads to a better furnace performance. Thus, a higher furnace productivity can be achieved by increasing either the upper-row injection rate or the microwave power. However, the latter seems more promising as it decreases the total energy demand due to a better utilization of thermal energy. Based on the comparison of two representative examples, the decrease in the total energy demand is about 0.2 GJ/t-Fe.

CO2 Abatement in the Steel Industry through Carbon Recycle and Electrification by Means of Advanced Polymer Membranes

The potential of advanced polymer or hybrid polymer membranes to reduce CO2 emissions in steel production was evaluated. For this, a conceptual process design and assessment was performed for a process that is a combination of carbon recycling and electrification of the steel making process. The results indicate a CO2 avoidance of 9%. CO2 emissions were reduced by factor 1.78 when using renewable electricity according to the proposed scheme compared to feeding this renewable electricity to the electrical grid. The CO2 abatement potential of the studied concept is highly dependent on the CO2 conversion in the plasma torch. If CO2 conversion in the plasma torch could be increased from 84.4% to 95.0%, the overall CO2 avoidance could be further increased to 16.5%, which is comparable to the values reported for the top gas recycling blast furnace. In this case, the CO2 emissions reduction achieved when using renewable electricity in the proposed scheme compared to using the same electricity in the electrical grid increases a factor from 1.78 to 3.27.

Challenges and Outlines of Steelmaking toward the Year 2030 and Beyond—Indian Perspective

In FY-20, India’s steel production was 109 MT, and it is the second-largest steel producer on the planet, after China. India’s per capita consumption of steel was around 75 kg, which has risen from 59 kg in FY-14. Despite the increase in consumption, it is much lower than the average global consumption of 230 kg. The per capita consumption of steel is one of the strongest indicators of economic development across the nation. Thus, India has an ambitious plan of increasing steel production to around 250 MT and per capita consumption to around 160 kg by the year 2030. Steel manufacturers in India can be classified based on production routes as (a) oxygen route (BF/BOF route) and (b) electric route (electric arc furnace and induction furnace). One of the major issues for manufacturers of both routes is the availability of raw materials such as iron ore, direct reduced iron (DRI), and scrap. To achieve the level of 250 MT, steel manufacturers have to focus on improving the current process and product scenario as well as on research and development activities. The challenge to stop global warming has forced the global steel industry to strongly cut its CO2 emissions. In the case of India, this target will be extremely difficult by ruling in the production duplication planned by the year 2030. This work focuses on the recent developments of various processes and challenges associated with them. Possibilities and opportunities for improving the current processes such as top gas recycling, increasing pulverized coal injection, and hydrogenation as well as the implementation of new processes such as HIsarna and other CO2-lean iron production technologies are discussed. In addition, the eventual transition to hydrogen ironmaking and “green” electricity in smelting are considered. By fast-acting improvements in current facilities and brave investments in new carbon-lean technologies, the CO2 emissions of the Indian steel industry can peak and turn downward toward carbon-neutral production.

A downscaling cold model for solid flow behaviour in a top gas recycling-oxygen blast furnace

The top gas recycling-oxygen blast furnace (TGR-OBF) is a reasonable method used to reduce both coke rate and energy consumption in the steel industry. An important feature of this process is shaft gas injection. This article presents an experimental study on the gas–solid flow characteristics in a TGR-OBF using a two-dimensional cold model. The experimental conditions and parameters were determined using a series of similarity criteria. The results showed that the whole flow area in the TGR-OBF can be divided into four distinct flow zones, namely, the stagnant zone, the plug flow zone in the upper part of the shaft, the converging flow zone and the quasi-stagnant flow zone, which is similar to that in a traditional blast furnace. Then the effects of batch weight and the ratio (X) of the shaft injected gas flow rate to the total gas flow rate on solid flow behaviour were investigated in detail. With the increase in batch weight, the shape of the stagnant zone tends to be shorter and thicker. Furthermore, with the increase in X value from 0 to 1, the stagnant zone gradually becomes thinner and higher. The results obtained from the experiments provide fundamental data and a validation for the discrete element method–computational fluid dynamics-coupled mathematical model for TGR-OBFs for future studies.

Numerical Investigation on Coal Combustion in Ultralow CO2 Blast Furnace: Effect of Oxygen Temperature

The cooling effect of room-temperature oxygen in oxygen blast furnaces with top gas recycling (TGR-OBF) delays the coal combustion process. To further explore the oxygen–coal combustion mechanism and intensify coal combustion in TGR-OBF, the effect of oxygen temperature on coal combustion was investigated using computational fluid dynamics (CFD). A three-dimensional model was developed to simulate the lance–blowpipe–tuyere–raceway of TGR-OBF. The effect of oxygen temperature at the same oxygen velocity and mass flow on coal combustion was investigated. Results showed the cooling effect of room-temperature oxygen was weakened, and the coal burnout was greatly increased with the increase in oxygen temperature. In particular, the coal burnout increased from 21.64% to 81.98% at the same oxygen velocity when the oxygen temperature increased from 300 to 500 K. The results provide useful reference for the development of TGR-OBF and coal combustion technology.