Specifications for steam turbine oil filtration

The filtration specifications for turbine oil involve many indicators such as cleanliness, moisture, gas content and chemical properties, and must strictly comply with international standards (such as ISO, ASTM) and manufacturer technical specifications (such as GE, Siemens). The following are key specification points and operation guidelines:

Cleanliness level standard

1. Particle contamination (core indicator)

| Standard system | Maximum allowed level | Applicable scenarios | Detection method |

|----------------|-------------------------|---------------------------|--------------------------|

| ISO 4406 | 14/12/10 (gas turbine) | GE/Siemens unit | Automatic particle counter (≥4/6/14μm) |

| | 15/13/11 (steam turbine) | Conventional power plant | |

| NAS 1638 | Level 6 (gas turbine) | Combined cycle unit | Microscope method (100mL oil sample) |

| | Level 7 (industrial steam turbine) | Petrochemical drive equipment | |

| SAE AS4059 | Level 5 (aero-derivative) | Aero-derivative gas turbine | Laser particle counting |

2. Filtration accuracy requirements

- Main oil line filter: β≥200 (3μm particle retention rate ≥99.5%)

- Servo system bypass: β≥1000 (1μm particle retention rate ≥99.9%)

- Before new oil is injected, it must pass through a 1μm absolute filter (β≥1000)

Moisture and gas control

| Parameters | New oil standard | Operating oil limit | Treatment method |

|----------------|-------------|---------------------|--------------------------|

| Moisture content | ≤50ppm | ≤100ppm (conventional) | Vacuum dehydration (-95kPa, 60℃) |

| | | ≤30ppm (nuclear power) | Molecular sieve adsorption |

| Air release value | ≤3min | ≤5min (ASTM D3427) | Degassing tower or coalescing separator |

| Foam characteristics | ≤300mL | ≤500mL (ASTM D892) | Silica gel adsorption or anti-foaming agent addition |

Chemical performance maintenance

| Indicators | Control limits | Exceeding treatment measures |

|------------------|-------------------------|---------------------------|

| Acid value | ≤0.2mg KOH/g (new oil) | White clay filtration or alkali washing neutralization |

| | ≤0.5mg KOH/g (operating oil) | |

| Oxidation stability | RPVOT≥300min (ASTM D2272) | Add antioxidant (T501) |

| Flash point | ≥200℃ (closed cup) | Eliminate light oil pollution |

Technical requirements for filtration equipment

1. Offline oil filter

- Vacuum oil filter:

- Vacuum degree ≤1mbar (such as Alfa Laval MAB series)

- Heating temperature ≤65℃ (anti-oxidation)

- Centrifugal separator:

- Separation factor Z ≥ 8000 (Westfalia OSA series)

- Processing volume ≥ 20% of system oil volume

2. Online filtration system

- Main pump outlet filter:

- Pressure differential alarm setting value: 0.15MPa

- Filter element material: glass fiber (high temperature resistant)

- Bypass fine filter device:

- Continuous operation flow: 5%~10% system oil volume

Operation process specification

1. New oil treatment:

- Three-stage filtration: storage tank → transfer pump → refueling truck → unit oil tank (all require 1μm filtration).

2. Daily maintenance:

- Monthly particle size/water content test, quarterly full analysis (including RPVOT).

3. Start-up after overhaul:

- Oil circulation for 48 hours, cleanliness meets the standard (ISO≤14/12/10) before flushing.

Safety and environmental protection

- Explosion-proof requirements: ATEX certification (equipment in gas turbine cabin).

- Waste oil disposal:

- PCB oil: high temperature incineration (≥1200℃)

- Ordinary waste oil: recycling (GB/T 14541)

Manufacturer's special requirements

| Manufacturer | Cleanliness requirements | Other specifications |

|------------|---------------------|-----------------------------|

| GE | ISO 14/12/10 | Silica gel adsorption is prohibited (to avoid loss of anti-foaming agent) |

| Siemens | NAS Level 6 | Moisture ≤50ppm (VGB standard) |

| Mitsubishi | JIS B 9930 Class 4 | Foam characteristics ≤200mL |

Common violation risks

- Excessive particles: causing wear of bearing babbitt alloy (repair cost ≥￥500,000).

- Excessive moisture: causes oil film oscillation (vibration value exceeds the standard and the machine trips).

- Increased acid value: accelerates seal aging (leakage risk ↑300%).

Turbine oil filtration must strictly implement the "monitoring → filtration → verification" closed-loop management. It is recommended to configure an online monitoring + bypass fine filtration system (such as Pall Ultipor + Donaldson combination), which can reduce unplanned downtime by more than 70%. The specific parameters must be based on the equipment O&M manual. If necessary, consult the oil supplier (such as Shell, Mobil) for a customized solution design.