Internal Compression Process Air Separation Equipment
Overview
Internal Compression Air Separation Equipment (ASU) produces high-pressure gaseous oxygen (GOX), nitrogen (GAN), and liquid co-products without external high-pressure gaseous oxygen compressors. This removes the need for downstream high-pressure oxygen gas compressors, reducing rotating equipment and associated oxygen ignition risks.
Technical Specifications
|
Parameter |
Specification |
|
Process Type |
Internal Compression Air Separation |
|
Oxygen Capacity |
10,000 Nm³/h |
|
Oxygen Purity |
99.6% O₂ |
|
Oxygen Pressure |
4.0–8.25 MPa (Gauge) |
|
Nitrogen Capacity |
12,000 Nm³/h |
|
Nitrogen Purity |
≤10 ppm O₂ |
|
Nitrogen Pressure |
0.8 MPa (Gauge) |
|
Refined Argon Capacity |
320 Nm³/h |
|
Specific Power Consumption |
~0.41–0.48 kWh/Nm³ GOX at 4.0 MPa |
|
Cold Start-Up Time |
~24 hours |
|
Primary Power Supply |
6/10/11 kV, 50/60 Hz |
|
Control System |
DCS/PLC (Siemens/ABB/Yokogawa or equivalent) |
Oxygen & Nitrogen Capacity
|
Parameter |
Scalable Capacity Range |
|
Oxygen Design Capacity Range |
5,000 – 30,000 Nm³/h |
|
Nitrogen Design Capacity Range |
5,000 – 35,000 Nm³/h |
|
Liquid Oxygen (LOX) Co-product |
Up to 10% of total oxygen flow |
|
Liquid Nitrogen (LIN) Co-product |
Up to 10% of total nitrogen flow |
|
Crude / Refined Argon Capacity Range |
150 – 900 Nm³/h |
|
Normal Plant Turndown Limit |
Down to 70% of rated capacity |
|
Maximum Operating Capacity |
Up to 105% of rated capacity (subject to project design) |
Internal Compression Process Flow
Air Compression: Atmospheric air passes through a self-cleaning filter into a multi-stage centrifugal air compressor.
Pre-Cooling: Compressed air enters a direct-contact cooling tower to lower process temperature before purification.
Molecular Sieve Purification: A dual-bed thermal swing adsorption (TSA) system removes moisture, carbon dioxide, acetylene, and other hydrocarbons.
Main Heat Exchange: Purified air enters a brazed aluminum plate-fin heat exchanger (BAHX) to exchange heat with cold return streams.
Cryogenic Distillation: Air enters a double-column system (high-pressure and low-pressure columns) for separation into oxygen, nitrogen, and argon fractions.
Liquid Oxygen Pumping: Liquid oxygen (LOX) from the low-pressure column is pressurized by a cryogenic liquid pump to the required project pressure.
Internal Vaporization: High-pressure LOX vaporizes within the main heat exchanger, discharging directly as high-pressure GOX to the battery limit.
Energy Consumption & Operating Performance
Specific Power Consumption: ~0.41 – 0.48 kWh/Nm³ GOX (at 4.0 MPa delivery pressure; final value depends on local ambient temperature and cooling water conditions).
Liquid Oxygen Compression Power Demand: Liquid oxygen pumping generally requires less electrical power than compressing the equivalent oxygen flow in the gaseous state.
Partial-Load Performance: Automated control logic adjusts feed air volume during reduced demand, maintaining product purity while lowering power usage.
Pump Redundancy: 1 operating + 1 full-capacity standby pump configuration for both LOX and LIN services to prevent process trips upon pump switchover.
Safety Design
Reduced Ignition Hazard: Removing the need for high-pressure oxygen gas compressors reduces the associated rotating-equipment and ignition risks.
LOX Pump: Bronze or Monel fluid ends, barrier gas seals, and motor enclosures with electrical protection are selected according to the applicable area classification and project requirements.
Safety Instrumented System (SIS): Independent interlocks trigger automated isolation or safe shutdown upon detection of high bearing temperatures, overpressure, or off-spec product purity.
Compliance
Quality Management Systems: ISO 9001 and ISO 14001 certified management systems.
Pressure Equipment Compliance: ASME Code Section VIII Div. 1 / Div. 2 (U Stamp available upon request); European Pressure Equipment Directive (PED 2014/68/EU / CE Mark).
Technical Documentation Package: EN 10204 3.1 material test certificates, hydrostatic pressure test reports, NDT inspection logs, factory acceptance test (FAT) reports, and installation manuals delivered with each project.
FAQ
Q: What is the typical lead time from contract signing to start-up?
A: A 10,000 Nm³/h unit ships in 12–16 months, with on-site installation taking 6–9 months and commissioning taking another 4–6 weeks. Units above 20,000 Nm³/h may take 18–22 months.
Q: How much does energy use change with delivery pressure and ambient temperature?
A: Specific power rises by roughly 0.02–0.03 kWh/Nm³ when oxygen pressure increases from 4.0 to 8.0 MPa. Every 10°C rise in cooling-water temperature adds about 1.5–2.5% to total power consumption.
Q: How long do the LOX pump and main components last?
A: LOX pumps need seal and bearing service every 16,000–24,000 hours, while the cold box and BAHX last 25–30 years. The molecular sieve is replaced every 5–7 years, and the main air compressor overhaul is typically every 40,000–50,000 hours.
Q: Should I choose internal or external compression for my project?
A: Choose internal compression when oxygen is required at 4.0 MPa or above, such as for coal or biomass gasification and cylinder filling. Below 3.0 MPa, as in most steelmaking and glass furnaces, external compression usually has lower capital cost and wider load flexibility.
Q: When does an on-site plant beat buying liquid oxygen?
A: On-site production usually pays back in 3–5 years when continuous oxygen demand exceeds about 3,000 Nm³/h, or when liquid delivery distance exceeds 300 km. Intermittent demand under 1,000 Nm³/h generally favors liquid supply.
Q: What site conditions and utilities does the plant require?
A: A 10,000 Nm³/h plant typically needs about 60 m × 40 m of plot area, 45–55 m of cold box clearance, and 100–150 tons of crane capacity. Cooling water consumption is about 1,800–2,200 m³/h, with 10 kV power supply.
Q: What after-sales support do you provide?
A: Warranty is 12 months from acceptance or 18 months from shipment, whichever ends first, with 24/7 remote diagnostics and on-site engineers dispatched within 7 days.
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