In recent years, India’s iron & steel production has maintained rapid growth on an on-going basis. In 2018, India surpassed Japan to become the world’s second-largest iron & steel manufacturer after China with an annual crude steel output of 106.5 million tons. According to the national iron & steel development plan formulated by the Indian government, India’s iron & steel manufacturing capacity will reach 300 million tons in 2030. By then, it will be difficult for the countries behind India to surpass its second position.

Compared with China’s major blast furnace ironmaking process, with non-coking coal and non-metallurgical coke as the main ironmaking raw materials, India mainly produces direct reduced iron, accounting for about 44% of the pig iron output. Given that the direct reduced iron process is not suitable for large-scale production and that India lacks coking coal, India has great potential for the long-term development of blast furnaces. The iron & steel industry in India is highly concentrated; in 2016, the steel CR3 level reached 44%, and large steel mills including JSW and TATA hit the level of world-class level. Currently, oxygen-enriched coal injection for blast furnaces in India has followed the trend of China’s iron & steel industry in choosing oxygen generation technologies. In 2016, VPSA oxygen generation process was applied for blast furnaces for the first time in India. Subsequently, large Indian iron & steel groups including JSW, JSPL and BPSL have successively built multiple sets of VPSA oxygen units, all of which are used for oxygen-enriched blast furnace ironmaking.

Diversified Oxygen Enrichment Solutions

Oxygen enrichment plays the most important role in the production increase of blast furnaces. Despite that Indian iron & steel companies have practiced oxygen enrichment technology for a long time, they began to popularize and promote oxygen enrichment before the blast furnace (BF) blower only a few years ago. Part of the reason is that they can only choose oxygen enrichment after the blower, combining VPSA oxygen generator with the compressor, due to the limitation of the BF blower to the operating conditions and oxygen purity.

Compared with cryogenic air separation, VPSA oxygen generation technology can greatly lower the energy consumption, thereby reducing the ironmaking cost. Indian iron & steel mills have fully applied the advanced experience of China iron and steel companies in oxy-coal injection of blast furnace, recognizing the process & solutions of partial use (subject to the limitation of blast furnace blower) or complete use of oxygen enrichment before the BF blower, which can not only save the investment on oxygen compressors, but also save more energy.

1. Oxygen Enrichment Before Blower

If the maximum oxygen enrichment rate of the blower could reach 30%，sending oxygen into blast furnace system by the suction of the BF blower is the most suitable oxygen enrichment technique for blast furnaces, which could not only lower the investment on oxygen compressors, but also save the relevant manual operation and maintenance costs. In line with the oxygen demand of iron & steel mills, the systematical solutions of VPSA oxygen system in conjunction with oxygen enrichment before the blower has shown great maturity, including the VPSA oxygen plant, oxygen pipeline system with flow and pressure control device, security nitrogen pipeline, oxygen mixing devices at the inlet of the blast furnace blower, and system control device, etc. The fluctuation of the oxygen-enriched air concentration after the mixer can be controlled within 0.5% through the joint control of the system, and a series of safety precautions including real-time monitoring of the oxygen purity at the blower inlet, automatic flow adjustment, automatic oxygen cutoff & nitrogen charging protection in emergency situations are available to maximumly ensure oxygen enrichment under normal conditions and full safety in emergencies.

PKU Pioneer’s VPSA Oxygen Equipment-Offer Superb Solution to Blast Furnace Oxygen Enrichment Before the Blower

2.  Big Difference in BF Oxygen Enrichment Rates

Every 1% increase of oxygen enrichment rate witnesses at least 3% growth in the output. Most companies in the world reckon that the enriched oxygen volume for blast furnaces shall be controlled within 30%. Different from many China iron & steel companies that adopt oxygen enrichment rate of about 6%, some conventional iron and steel plants in India require 3~4%, while others require 8~9%. With the growing public acceptance of oxygen enrichment before the blower in India, oxygen enrichment rates ranging from the lowest 4% to the highest 9% are all applied. For iron and steel plants requiring 3~4%, the oxygen enrichment before the BF blower can fully meet the demands; but 8~9% will be limited by the BF blower, thus it’s achieved by making the oxygen enrichment rate 4~5% before the blower and 4~5% after the blower respectively.

Table 3 Data Comparison of Oxygen Enrichment Solution (*Oxygen Enrichment Before Blower: 6000*90%, After Blower: 6000*90%+7000)

Oxygen enrichment in blast furnace (BF) ironmaking can not only raise coal injection quantity & lower the coke ratio but also helps to improve the smelting intensity and output as well as increase the BFG heat value. Based on these advantages, more and more Indian iron & steel mills tend to adopt BF oxygen enrichment technology to reduce energy consumption and lift profit margins. With the rapid development of VPSA oxygen generation technology, especially the breakthrough of radial adsorbers, the total capacity of oxygen systems in a single iron & steel mill has reached 70,000Nm3/h (pure oxygen). The low power consumption, easy load regulation and high degree of automation of VPSA oxygen plant make it the preferred choice of oxygen production equipment for blast furnaces.