Yes, turbine oil can and should be filtered to ensure that it remains clean, efficient, and capable of performing its critical functions in turbine systems. Turbine oil serves multiple purposes: it acts as a lubricant, a coolant, and a sealant for turbine components. Over time, turbine oil can become contaminated with solid particles, water, gases, and oxidation products, which can degrade its performance and the efficiency of the turbine. Regular filtration helps remove these contaminants, improving the longevity and reliability of both the oil and the turbine.
Types of Contaminants in Turbine Oil
- Solid Particulates: Dust, dirt, metal shavings, and sludge from internal wear or external sources.
- Water: Free water, emulsified water, or dissolved water that can cause corrosion, oxidation, and loss of lubrication properties.
- Gases: Dissolved gases (e.g., oxygen, nitrogen, carbon dioxide) can lower the oil’s performance and insulation properties.
- Oxidation Products: Acids, varnish, and sludge from the oil breaking down due to heat and oxygen exposure.
Benefits of Filtering Turbine Oil:
- Improves Lubrication: Removes solid particles that could cause wear and tear on turbine components.
- Prevents Corrosion: Removes water that can cause rusting and corrosion of internal metal parts.
- Restores Dielectric Strength: Removes dissolved gases and moisture, helping to maintain the oil’s electrical insulating properties (especially important for steam turbines).
- Reduces Varnish Formation: Filters out oxidation byproducts and varnish, keeping the oil clean and reducing the risk of varnish buildup on turbine components.
- Extends Oil Life: Filtering contaminants prolongs the service life of the oil, reducing the need for oil changes.
Methods for Filtering Turbine Oil:
Mechanical Filtration:
- Coarse Filtration: Removes larger particles and contaminants (typically larger than 10 microns) such as dust and debris.
- Fine Filtration: Removes smaller particles (typically less than 1 micron), such as carbon, wear particles, and sludge. High-efficiency filters can achieve filtration down to 0.5 microns.
- Magnetic Filtration: A specialized method used to remove ferrous (magnetic) particles from the oil. It uses a magnetic field to attract and capture metallic debris, such as iron or steel particles.
- Pleated Filters: Often used for fine filtration, pleated filters provide a larger surface area for trapping contaminants.
- Bag Filters: These are commonly used for larger volumes of oil and can capture solid particles that are larger in size.
Centrifugal Filtration:
- Centrifugal Purifiers use centrifugal force to separate contaminants from the oil. The oil is spun at high speeds, forcing heavier particles, water, and sludge to the outer edges of the separator, leaving cleaner oil in the center.
- Benefits: Effective for removing both solid particles and free water from turbine oil.
Vacuum Filtration:
- Vacuum Dehydration removes free and dissolved water, and sometimes gases, from the oil by applying a vacuum. This process lowers the boiling point of water, allowing it to evaporate and separate from the oil without affecting the oil itself.
- Application: This method is often used for large-volume applications where water contamination is significant and needs to be removed from the oil.
Clay Filtration:
- Fuller's Earth or activated clay can be used to adsorb contaminants like oxidation byproducts, acids, and sludge. This type of filtration is typically used for removing chemical contaminants that affect the oil’s properties and performance.
- Application: Clay filtration can also help remove varnish and discoloration in turbine oils.
Electrostatic Filtration:
- Electrostatic oil purifiers use electrical charges to attract and remove tiny particles from the oil. This is particularly useful for removing fine particulate matter and is often used for oils that have varnish or other fine contaminants.
- Application: Electrostatic filtration can be highly effective for turbine oils, particularly when varnish or micro-contaminants are present in the oil.
Portable Oil Filtration Units:
- Mobile Filtration Systems are often used for on-site purification of turbine oil. These systems can be connected to the turbine oil system and filter the oil without the need to shut down the machinery, providing continuous purification.
- Benefits: These portable units are ideal for emergency oil filtration or routine maintenance, especially in large power plants or industrial settings.
Key Considerations When Filtering Turbine Oil:
- Filter Size and Efficiency: The size of the filter and its ability to capture specific types of contaminants is crucial. Fine filtration may be needed for varnish and oxidation byproducts, while coarse filtration may suffice for larger debris.
- Water and Gas Removal: For turbines, it’s essential to remove both water (which causes corrosion) and dissolved gases (which degrade insulation properties). Vacuum dehydration and centrifugal separators are highly effective for water and gas removal.
- Maintenance: Filters need to be monitored and changed regularly to ensure they remain effective. Overused filters can become clogged and inefficient, potentially allowing contaminants to pass through.
- Oil Type and Application: Different turbines may require specific oil purification methods based on the type of oil (mineral, synthetic, or biodegradable) and the operational conditions (high heat, exposure to moisture, etc.).
Popular Turbine Oil Filtration Systems:
- CJC (Continuous Oil Cleaning) – Known for its offline filtration systems that remove both solid particles and water, prolonging oil life and improving performance.
- Alfa Laval – Offers centrifugal oil purifiers and vacuum dehydration systems that can remove both particulate and water contaminants effectively.
- Pall Corporation – Specializes in high-efficiency filtration systems, including portable and electrostatic filters for turbine oils.
- Des-Case – Provides portable filtration units and filtration systems designed for turbine oil, including both fine and coarse filtration options.
- Sorbtech – Offers systems that focus on the removal of oxidation products, sludge, and water from turbine oils.
Turbine oil can and should be filtered regularly to maintain its quality and protect turbine machinery. Filtration removes contaminants like solid particles, water, and oxidation byproducts, ensuring that the oil remains effective as a lubricant, coolant, and insulator. Several filtration methods—such as mechanical filtration, centrifugal separation, vacuum dehydration, and electrostatic purification—can be employed depending on the specific needs of the turbine system and the type of contaminants present. Regular oil filtration can extend the life of both the turbine and the oil, reduce maintenance costs, and prevent failures in turbine operations.
