Recently, Beijing Peking University Pioneer Technology Corporation Ltd. (hereinafter referred to as PKU Pioneer) issued an analysis report on the application of VPSA oxygen generation technology in blast furnace oxygen enrichment in India, which has caused an ardent response in related industries. PKU Pioneer’s VPSA oxygen production process has been applied in industrial areas for over 20 years. Through continuous technical optimization and product iteration, the ultra-large-capacity application of VPSA oxygen generation technology in the iron & steel industry has been realized. The total oxygen generation capacity of VPSA oxygen system in a single iron & steel mill has reached 87,500Nm3/h, which enables this technology to gain core competitiveness in the international market.
Abstract: Based on characteristics of blast furnace oxy-coal injection, this report expounds the process optimization and performance improvement of VPSA oxygen generation technology for Indian iron & steel mills.
Keywords: VPSA oxygen generation; blast furnace oxygen enrichment; oxygen enrichment rate
Introduction
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.
Body
Relying on the self-developed high-efficiency oxygen adsorbent, radial-bed adsorbers, excellent equipment performance and professional international business teams, PKU Pioneer has gradually opened up the international market of VPSA oxygen units with numerous successful industrial application cases in Asia, Africa, Europe and America. In India alone, PKU Pioneer has built and put into production over 20 sets of VPSA oxygen generators in the past 5 years, covering various industries including metal smelting and petrochemicals, among which the projects for top iron & steel companies make up the majority. Therefore, PKU Pioneer has accumulated rich experience in the design and service of both VPSA oxygen generation technology and supporting equipment in the overseas oxygen-rich coal injection projects for blast furnaces. Taking India as an example, the technical characteristics of PKU Pioneer’s blast furnace oxygen enrichment technology are summarized in the following four aspects:
1. Numerous Advantages of VPSA Oxygen Plant Projects
For many years, driven by PKU Pioneer, iron and steel companies in India have well recognized the VPSA oxygen equipment for its advantages of excellent performance, high level of automation and diversified customized services.
1.1. Excellent Performance
Compared with the local traditional cryogenic air separator, VPSA oxygen gas plant is superior in terms of safety, energy consumption, start-up and shut-down time, load regulation, construction period and profits on the investment.
1.2. High Level of Automation
In response to the diel temperature variations and seasonal characteristics in India, during the construction of the first 200TPD VPSA oxygen system for a steel mill in India, after a theoretical analysis on the impact of temperature changes on the oxygen system, according to the equipment composition and operation principles, PKU Pioneer proposed the automatic adjustment control scheme of capacity & purity, which was realized by the PLC control system. Through automatic adjustment of the valve opening and the travel time of each step by comparing the feedback data, a more stable, energy-saving and efficient oxygen source for blast oxygen enrichment is realized by VPSA oxygen generation technology. In the Phase II oxygen generation project of another steel plant, PKU Pioneer added such automatic functions as load regulation, fault removal and temperature control to further improve the automaticity of the oxygen unit and ensure its stable operation [1] .
1.3. Diversified Services
In addition to conventional design, installation, commissioning, operation and maintenance services for India projects, PKU Pioneer provides oxygen enrichment solutions, overall relocation guidance and remote instruction services as well.
2. Diversified Oxygen Enrichment Solutions
Oxygen enrichment plays the most important role in the production increase of blast furnaces [2]. 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 into 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.
2.1. Oxygen Enrichment Before Blower
If the maximum oxygen enrichment rate of the blower could reach 30% [3], 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. [4]. 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.
2.2 Big Difference in BF Oxygen Enrichment Rates
Every 1% increase of oxygen enrichment rate witnesses at least 3% growth in the output [5]. 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.
3. Integral Relocation
Large iron & steel mills in India are usually distributed in various places, and the VPSA oxygen equipment relocation is frequently needed due to insufficient oxygen supply or slow construction of air separation units, so as to quickly make up the oxygen shortage. When prepared, VPSA oxygen generator system can be well reinstalled on site during only over 1 month for oxygen generation with no need of unloading or refilling, thus realizing one-off relocation of complete sets of VPSA oxygen plants. Under the premises that the iron & steel mill well cooperated with the overall relocation scheme and reconstruction plans, it takes only less than 3 months to cross-provincially resettle an oxygen generating unit (6000Nm3/h) being constructed to a city 300 kilometers away upon the request of a steel mill headquarters in India under the remote guidance of PKU Pioneer’s technical team; After years of use, another 3 oxygen generating units (5000Nm3/h) were relocated to a site 766 kilometers away as per the overall plan of the customer in less than 4 months.
4. Offering Remote Services in the COVID-19 Pandemic
Since 2020, India has been hard hit by the COVID-19 outbreak, causing severe economic downturn and bringing a huge challenge for Chinese companies to implement localized engineering services as well. Currently, although China has been carrying out COVID-19 prevention and control measures on an on-going basis, it is still impossible for PKU Pioneer technical teams to guide the installation on site in India even after coordinating among multiple parties. In this regard, PKU Pioneer has reached an agreement with clients on the premise of ensuring equivalent construction quality, and completed the whole-process guidance from construction, debugging to commissioning of at least 5 VPSA oxygen generating system projects through remote services, with the implementation procedures and final results of each oxygen units receiving high compliments from the users. PKU Pioneer is greatly encouraged to promote international business and more diversified service models at present and in the future: Chinese VPSA oxygen plants could be sent to any places where Chinese goods can reach.
Conclusion
In conclusion, judging from PKU Pioneer’s practical project implementations in India, VPSA oxygen plant applies to a variety of blast furnace oxygen enrichment solutions. It’s able to meet manifold needs of global users, and can well adapt to ever changing international situations. In the context of the Belt and Road Initiative, VPSA oxygen units will usher in a broader application prospect in oxygen-enriched blast furnace ironmaking projects around the world in the future by virtue of their huge advantages in construction period, investment, level of automation, installation and maintenance, coupled with professional service teams.
References
[1] Li Jian, Shan Yi. Application of Automatic Control in VPSA Oxygen Production System [J]. Automatic Instrumentation, 2021, (1st Issue).
[2] Tu Chunlin. The Intensified Smelting Practice of No.7 Blast Furnace in LY Steel [J]. Metal Materials and Metallurgy Engineering, 2011, (1st Issue).
[3] Liu Dianyao. The Current Situation of Oxygen-enriched Blast of Blast Furnace and Oxygen Supply Before the Blower [J]. Metallurgical Power, 2003, (6th Issue).
[4] Li Kunpeng1, Wu Xianjie1, Sun Yonglai1, Han Jiangwen2, Wang Zengbei2. Practical Analysis for Innovation of Oxygen Enrichment Before Blower [J]. Energy for Metallurgical Industry, 2017, (4th Issue).
[5] Jiang He. Advancement of VPSA Oxygen Generation Technology [J]. China Nonferrous Metallurgy, 2014, (2nd Issue).
Media Contact
Contact Person: Joyce Young
Company Name: Beijing Peking University Pioneer Technology Corporation Ltd.
Address: 4-5th Floor, New Times Mansion, No. 7 Huayuan Road, Haidian District, Beijing, China
Website: www.vpsatech.com / www.vpsagas.com
Email: [email protected]/ [email protected]
