In steelmaking and chemical production, a continuous and stable oxygen supply directly affects output, energy consumption, and operational safety. Compared to traditional liquid oxygen purchasing, on-site industrial oxygen generators are becoming a practical choice for many manufacturers. Shenger Gas, as a player in the gas separation field, focuses on how oxygen generation technologies fit different real-world conditions. This article looks at how industrial oxygen generators bring value to steel and chemical sectors, and what to consider when selecting a system.
Steel Industry: From Oxygen Enrichment to Blast Furnace Support
Steel production consumes large amounts of oxygen. On average, producing one ton of crude steel requires about 100 to 150 cubic meters of pure oxygen. The main applications include:
1. Oxygen-enriched blast furnace injection
Adding pure oxygen to the blast furnace air increases combustion temperature at the tuyere, allows more pulverized coal injection, and reduces coke usage. In practice, every 1% increase in oxygen enrichment raises coal injection by 15–20 kg per ton of iron, and lowers coke consumption by about 5–8 kg per ton of iron. Industrial oxygen generators provide 90% to 99.6% oxygen concentration. Both VPSA (vacuum pressure swing adsorption) and cryogenic air separation units can meet the continuous oxygen demand of blast furnaces.
2. Basic oxygen furnace (BOF) steelmaking
BOF processes require high-purity oxygen (≥99.5%) for decarburization and temperature control. Oxygen demand fluctuates sharply, with peak flows reaching 20,000 to 80,000 Nm³/h. Cryogenic air separation units handle high flow rates and high purity, while liquid oxygen backup ensures stability. Byproduct nitrogen and argon also improve overall economics.
3. Electric arc furnace (EAF) and ladle refining
EAF melting benefits from oxygen-assisted combustion, shortening melting cycles. In ladle refining furnaces (LF), oxygen supports desulfurization and dephosphorization reactions. These applications require intermittent oxygen supply at 0.8–1.2 MPa. VPSA oxygen generators, with their flexible start-stop capability and easier maintenance, are adopted by many medium-sized steel plants.
Selection tip
For large integrated steel mills producing over 3 million tons per year, cryogenic air separation with liquid backup is the standard choice. For smaller mills under 1 million tons, or for heating furnace enrichment, VPSA units offer 30–40% lower upfront investment and 15–25% lower overall operating costs.
Chemical Industry: Rigid Demand for Oxidation and Gasification
Chemical plants are more demanding when it comes to oxygen purity, pressure, and reliability, because oxygen cost directly impacts final product margins.
1. Ammonia and methanol production
In natural gas or coal-based ammonia production, pure oxygen is required for partial oxidation gasification to produce syngas (CO + H₂). Oxygen purity should be at least 99.5%, with tight limits on impurities like argon. Producing one ton of ammonia consumes about 700–850 Nm³ of oxygen. Large chemical projects typically install cryogenic air separation units, which also supply nitrogen for purging and sealing.
2. Ethylene oxide / ethylene glycol (EO/EG)
The catalyst used to oxidize ethylene into ethylene oxide is highly sensitive to oxygen purity. Methane content in oxygen must stay below 0.1%, and total sulfur below 0.1 ppm. This kind of application requires cryogenic oxygen production, followed by additional desulfurization and drying steps.
3. Coal gasification and IGCC
Entrained-flow gasification technologies (such as Shell, GSP, or opposed multi-burner designs) need oxygen at 4.0–8.5 MPa with stable flow. The industry standard is cryogenic oxygen production combined with high-pressure liquid oxygen pumps and vaporization. For lower-pressure fixed-bed gasifiers, 90–93% oxygen-enriched air can improve gasification intensity. In those cases, VPSA units offer a lower-cost alternative.
4. Wastewater treatment and ozone oxidation
Chemical industrial parks frequently use ozone oxidation to break down refractory organic compounds in wastewater. Ozone generation requires an oxygen feed. Small flows (≤500 Nm³/h) at 90–95% purity are sufficient. Compact PSA oxygen generators are a good fit here - they run automatically, require little space, and can be installed outdoors.
Key cost indicator
In chemical projects, calculating oxygen cost per unit of product is essential. If electricity costs exceed 0.6 yuan/kWh and oxygen demand is stable, cryogenic units show better efficiency. If electricity is cheaper and there is no demand for byproducts (argon, helium), VPSA oxygen generators consume only 0.35–0.45 kWh per Nm³ (at 90% purity) - a cost-effective option for fine chemicals or early-stage coal chemical investments.
Comparison of Industrial Oxygen Generator Technologies
|
Parameter |
Cryogenic Air Separation |
VPSA |
PSA |
|
Oxygen purity |
99.5%–99.99% |
90%–94% |
90%–95% |
|
Typical capacity |
1,000–100,000+ Nm³/h |
100–8,000 Nm³/h |
5–500 Nm³/h |
|
Start-up time |
6–24 hours (cold start) |
15–30 minutes |
5–10 minutes |
|
Best for |
Large scale, high purity, byproduct recovery |
Medium scale, flexible or batch use |
Small scale, unattended operation |
In some actual projects, plants use a combination: cryogenic units for main production (high purity) and VPSA for lower-grade oxygen demand (e.g., environmental treatment). This balances capital and energy costs.
Three Real-World Factors That Affect Oxygen Generator Performance
Based on feedback from multiple operating sites, these factors deserve attention before selection:
1. Inlet air quality
Steel plants and chemical facilities often release SO₂, NOx, dust, and hydrocarbons into the air. For cryogenic units, this means adding molecular sieve adsorbers and scheduling periodic cleaning. For VPSA systems, the zeolite molecular sieve has limited tolerance to acidic gases. Inlet air must pass through desulfurization towers and high-efficiency filters; otherwise, molecular sieve life may drop from 5–8 years down to 2–3 years.
2. Vent rate and load flexibility
Steel plant oxygen demand can swing by 30–40% between peak and off-peak hours. Cryogenic units need liquid oxygen storage tanks for peak shaving, or integration with an argon system. VPSA units adjust load between 50% and 100% by changing blower speed and adsorption timing, but the response takes about 30 seconds - fast enough for most mills.
3. Maintenance crew capability
Cryogenic air separation requires skilled operators who understand turbomachinery, distillation column control, and safety relief procedures. Training takes 6–12 months. PSA and VPSA units run on PLC-based automation. Daily maintenance mainly involves changing filters and topping up molecular sieve, making them suitable for smaller teams.
In the past two years, energy price swings and pressure to cut carbon have pushed many steel and chemical plants to re-evaluate on-site oxygen generation. Two approaches are gaining traction. One is using waste heat from blast furnace slag flushing water to preheat molecular sieve regeneration gas, cutting steam use. The other is the growing use of low-purity oxygen enrichment (25%-35%) in reheating furnaces and rotary kilns, which has driven demand for many small VPSA oxygen generators.
Choosing an oxygen generator isn't just about comparing equipment prices. You need to factor in oxygen purity, pressure, flow variation, electricity cost, what you can sell byproducts for, and maintenance intervals - all into the final cost per ton of oxygen. Shenger Gas gives pretty straightforward advice to customers: first, honestly track your oxygen usage data for six months, then decide on the process route. Otherwise, you either overpay for features you'll never use, or you get stuck with a bottleneck you can't break.
