What is the function of turbine oil filter?

The turbine oil filter is a key component in the turbine lubrication system. It is mainly used to protect the normal operation of turbine units (such as steam turbines, gas turbines, aircraft engines, etc.). Its core function is to purify lubricating oil and ensure that the cleanliness of the oil meets the equipment requirements. The following is a detailed description of its specific functions and working principles:

The main functions of turbine oil filters

1. Removal of solid particle pollutants

-Intercept metal wear particles in the oil (such as metal chips generated by bearing and gear wear), dust, sealing material debris, etc., to prevent particles from scratching precision friction pairs (such as bearings and gears) and avoid abnormal wear of equipment.

2. Separation of free water

- Some high-efficiency filters (such as coalescing or vacuum types) can separate free water in the oil to prevent water from causing oil emulsification, additive failure, or metal parts rust.

3. Extend the life of oil products

- By filtering oxidation products (such as sludge, colloid) and external pollutants, it slows down oil aging, reduces oil change frequency and operation and maintenance costs.

4. Protect lubrication system components

- Prevent contaminants from clogging the oil circuit, control valve, or nozzle, and ensure that the lubricating oil is stably supplied to key parts such as bearings and gears.

5. Maintain oil film strength

- Clean oil can form a stable lubricating oil film to avoid oil film rupture caused by particles or moisture, causing dry grinding or high-temperature sintering of friction pairs.

Working principle of the turbine oil filter

Turbine oil filter usually adopts a multi-stage filtration design, combining mechanical filtration and separation technology:

1. Primary filtration (coarse filtration)

- Use a metal mesh or a low-precision filter element (such as 20~50μm) to intercept large particles and protect the downstream precision filter element.

2. Fine filtration (main filtration)

- Use high-precision filter materials (such as glass fiber, sintered metal, precision 1~10μm) for deep purification to ensure that the oil reaches ISO 4406 or NAS 1638 cleanliness standards (such as NAS 6~8).

3. Optional additional functions

- Coalescing and dehydration: The coalescing filter element merges tiny water droplets into large droplets, which are then discharged through the separator.

- Magnetic adsorption: The built-in magnet captures ferromagnetic particles (common in gearbox oil filtration).

- Online monitoring: The differential pressure sensor indicates that the filter element is blocked, and the flow meter monitors the oil status.

Key performance requirements of turbine oil filters

1. High filtration accuracy

- Usually, 3~5μm (β≥200) is required to ensure that more than 99.5% of the target particles in the oil are intercepted.

2. High temperature and high pressure resistance

- The oil temperature of the turbine system can reach 60~80℃, and the filter material (such as glass fiber, stainless steel) and sealing material need to withstand high temperatures and not deform.

3. Low flow resistance

- To avoid affecting the oil supply pressure of the lubrication system due to excessive pressure ｄｒｏｐ, the filter element structure needs to be optimized (such as a pleated design to increase the filtration area).

4. Long life and easy maintenance

- The filter element needs to have high dirt holding capacity, reduce the frequency of replacement, and some designs support backwashing regeneration.

Typical application scenarios

1. Power plant steam turbine: prevent the bearing from vibrating beyond the standard due to particle wear.

2. Gas turbine: protect high-speed bearings and avoid failure caused by oil film failure.

3. Ship power system: maintain lubricating oil cleanliness in harsh environments.

4. Aircraft engine: ensure lubrication reliability under extreme conditions (must meet MIL standards).

 Maintenance points

- Regular inspection: evaluate the filter performance through oil particle counting and water content analysis.

- Pressure difference monitoring: the filter element needs to be replaced immediately if the pressure difference before and after exceeds the set value (such as 0.2MPa).

- Compatibility: when replacing the filter element, the chemical compatibility of the material and the oil (such as mineral oil, synthetic ester) must be confirmed.

The turbine oil filter is the "kidney" of the stable operation of the turbine, and its performance directly affects the equipment life and failure rate. The selection needs to be made based on comprehensive matching of unit parameters, oil type and pollution control standards.