Carbon Capture & CCUS
Carbon capture, utilization and storage (CCUS) compressor lubricants are selected for compressors handling captured CO₂ across conditioning, compression, transport, utilization and permanent geologic storage systems.
Unlike high-purity industrial CO₂, captured CO₂ composition depends on the emission source, capture technology and purification process. Residual moisture, oxygen, nitrogen, hydrogen, sulfur compounds, hydrocarbons and capture-solvent residues can influence corrosion, phase behavior, compression work and lubricant compatibility.
NEXT Lubricants works with PAO and PAG formulations for CCUS compression. Final lubricant selection depends on the conditioned CO₂ composition, compressor design, lubrication point, pressure, temperature and required operating viscosity.
This page covers captured CO₂ moving through the CCUS value chain. General industrial CO₂ compression and reservoir injection for enhanced oil recovery are addressed on their dedicated application pages.
Key takeaways
- CCUS captures CO₂ from industrial facilities, power generation or the atmosphere and conditions it for utilization or permanent geologic storage.
- Captured CO₂ composition varies with the emission source, capture method and purification process, making the actual stream specification important for lubricant selection.
- Moisture and impurities influence corrosion, phase behavior, compression requirements, materials compatibility and lubricant performance.
- Where CO₂ directly contacts the lubricant, dissolved gas can reduce operating viscosity and the film thickness available to protect compressor components.
- Lubricant exposure depends on compressor design. Bearing oil in many centrifugal compressors remains isolated from the process gas, while reciprocating and oil-injected compressors create different contact conditions.
- A preliminary recommendation can begin with the compressor model, current lubricant, available CO₂ specification and approximate operating conditions.
Compression process
How Carbon Capture and CCUS Work and the Compressor's Role
CCUS separates CO₂ from industrial process streams, combustion exhaust or ambient air. The captured stream is then purified, conditioned, dehydrated and compressed for transport, utilization or injection into a suitable geologic formation.
Compression frequently takes place in several stages with intercooling and condensate removal between stages. Large-volume CCUS projects often use integrally geared centrifugal compressors, while reciprocating or rotary screw compressors may be used for smaller flows, initial compression, booster service or specialized duties.
The lubricant protects bearings, gears, cylinders, piston rings, packing, rotors and other moving components. Its exposure to the CO₂ depends on the compressor design and lubrication point. Selection must therefore distinguish between bearing or gear oil isolated from the gas and lubricant that directly contacts the process stream.
Post-Combustion & Industrial CO₂ Capture
CO₂ is captured from cement, steel, hydrogen, chemical, refining, power-generation and other industrial processes before being conditioned and compressed.
CO₂ Conditioning & Dehydration
Water, capture-solvent residues and other impurities are reduced to meet the requirements of the compressor, transport system and final destination.
Dense-Phase Pipeline Transport
Captured CO₂ from one or more sources is compressed for collection hubs, pipeline transport, liquefaction, ship loading or onward movement to a storage or utilization site.
Geological Storage Injection
Compressed CO₂ is injected into deep saline formations or depleted reservoirs for permanent storage, or supplied to an industrial utilization process with its own pressure and purity requirements.
CO₂ Utilisation
Captured CO₂ may also be routed to industrial or chemical utilisation pathways rather than permanent storage. Where compression is part of the CCU chain, downstream purity requirements and process conditions also influence lubricant selection.
Direct Air Capture
Direct air capture removes CO₂ from ambient air. The initially low-pressure CO₂ stream requires compression and conditioning before transport, utilization or storage.
Selection
Factors Affecting Lubricant Selection
CCUS lubricant selection must account for the conditioned CO₂ composition, compressor design and complete operating envelope. The following factors determine the required chemistry and viscosity.
- Compressor Design and Lubrication Point Determine which components are lubricated, whether the oil contacts the CO₂ and whether separate bearing, gear, cylinder or seal-oil systems are used.
- Conditioned CO₂ Composition Identifies the CO₂ concentration and any oxygen, nitrogen, hydrogen, hydrocarbons, H₂S, sulfur oxides, nitrogen oxides or capture-solvent residues remaining in the stream.
- Moisture and Contamination Influence corrosion risk, lubricant condition, water separation, deposit formation and the effectiveness of the CO₂-conditioning system.
- Pressure, Temperature and Phase Behavior Determine compressor loading, CO₂ density, gas solubility, operating viscosity and whether the stream is gaseous, liquid-like, dense-phase or supercritical.
- Operating Profile and Project Requirements Include flow variation, continuous duty, startup conditions, required availability, materials, purity limits, carryover restrictions and OEM lubricant specifications.
Process
What NEXT needs to recommend a lubricant
A lubricant recommendation is based on the information below. Provide whatever information is available; NEXT will identify whether any additional details are required.
- Compressor Details Manufacturer, model, serial number and compressor type, such as reciprocating, rotary screw or centrifugal.
- Current Lubricant and Performance Current oil, oil volume, operating hours and any problems with viscosity, deposits, consumption, carryover or lubricant life.
- Gas Composition CO₂ concentration and any water, oxygen, nitrogen, hydrogen, hydrocarbons, H₂S, sulfur oxides, nitrogen oxides or capture-solvent residues. An existing CO₂ stream specification can also be provided.
- Operating Conditions Suction and discharge pressures and temperatures, oil temperature and relevant operating limits for each compression stage.
- Application and Specific Requirements How the compressor is used and any purity, catalyst, material-compatibility, minimum-viscosity or other application-specific requirements.
- Final Recommendation NEXT evaluates the available information and confirms the recommended product, lubricant chemistry and ISO viscosity grade, with compatibility and changeover guidance where required.
Benefits
Operational Benefits of Correct Lubricant Selection
Selecting the lubricant according to the CO₂ stream, compressor and complete operating envelope provides several operational benefits.
- Stable Operating Viscosity Helps maintain sufficient film strength at operating temperature and where pressurized CO₂ dissolves into the lubricant.
- Reduced Unplanned Downtime Helps prevent lubrication-related wear, overheating, deposits, contamination and unexpected compressor shutdowns.
- Extended Component Life Supports the protection of bearings, gears, cylinders, piston rings, packing, rotors and other lubricated components.
- Reliable High-Pressure CCUS Operation Supports continuous compression across capture, conditioning, transport and storage-injection duties.
- Clean Running and Deposit Control Helps minimize varnish, carbon, sludge and deposits for cleaner compressor and lubricant-system components.
- Longer and More Predictable Service Intervals Improves resistance to oxidation, contamination and viscosity change for more controlled maintenance planning.
products
Recommended NEXT Carbon Capture & CCUS Compressor Lubricants
NEXT GPL PAG-WS
High-Pressure / Dilution-Resistant CCUS Compression
Base Oil: PAG (EO/PO)
ISO Range: 32 – 320
Cross reference tool
Our technical team can help identify the right product.
TECHNICAL SUPPORT
Lubricant Selection, Technical Support and Compatibility Documentation
NEXT combines application knowledge, laboratory data and an extensive internal cross-reference database to support lubricant selection, conversions and compressor troubleshooting.
Depending on the application, we can provide:
- Application-Specific Product Recommendations Lubricant recommendations based on gas or refrigerant composition, compressor design, operating conditions and current performance issues.
- Lubricant Cross-Referencing Identifies suitable NEXT alternatives by comparing base-oil chemistry, viscosity, application, specifications and operating requirements.
- Compatibility and Conversion Documentation Provides chemistry comparisons, mixture-test data, material compatibility, flushing requirements and top-off or changeover guidance.
- Dilution Data and PVT Graphs Shows how gas or refrigerant concentration, pressure and temperature affect lubricant dilution, density and operating viscosity.
- Troubleshooting and Root-Cause Support Supports investigations into foaming, oil carryover, dilution, deposits, corrosion, high lubricant consumption and reduced oil life.
Frequently Asked question
What type of oil is used in carbon capture and CCUS compressors?
CCUS compressors can use PAO or PAG-based lubricants depending on compressor design, CO₂ purity, impurities, pressure, temperature and whether the process gas directly contacts the oil. NEXT’s current CCUS range includes GPL PAO, GPL PAG-WS and NEXT PAO.
Why are CO₂ impurities important in CCUS compression?
Captured CO₂ can contain residual water, oxygen, nitrogen, hydrogen, sulphur compounds and other impurities depending on the source and purification process. These components can influence corrosion, compression work, phase behavior and materials compatibility, so the actual conditioned CO₂ composition should be used for lubricant selection.
Why is moisture particularly important in captured CO₂?
Water can significantly increase corrosion risk, especially when sulphur or nitrogen compounds are also present. NETL notes that water with SOx or NOx can form acidic species and that dehydration is therefore an important part of CO₂ conditioning and transport design.
Does CO₂ become supercritical above 74 bar?
Not automatically. Pure CO₂ becomes supercritical only when both pressure and temperature are above its critical point, approximately 73.8 bar and 31°C. CCUS pipelines commonly transport CO₂ in a dense phase, which can include liquid-like or supercritical conditions depending on temperature and stream composition.
Does CO₂ reduce compressor oil viscosity in CCUS applications?
It can where CO₂ directly contacts the lubricant. Dissolved CO₂ can lower the viscosity of the oil-CO₂ mixture, so lubricant selection should consider expected in-service viscosity rather than fresh-oil ISO grade alone. The detailed solubility and viscosity-selection discussion is covered on the CO₂ Compression page.
Is captured CO₂ always more aggressive than industrial CO₂?
Not automatically. Captured CO₂ can contain more impurities than high-purity merchant CO₂, but conditioning and purification may reduce those contaminants substantially before transport. The correct approach is therefore to evaluate the actual stream specification at the compressor, rather than assuming every captured CO₂ stream is highly contaminated. NETL’s guidance shows wide impurity ranges depending on source and design.
Why is dehydration required before CO₂ pipeline transport?
Water increases corrosion risk and can interact with other impurities. DOE transport guidance therefore calls for CO₂ dehydration before dense-phase pipeline transport.
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