Product Introduction
The Generator Hydrogen Sealing Ring, also called sealing bearing, is installed at the generator rotor ends and inside the bearing to seal the hydrogen in the generator stator. It has an internal oil ring which inlets sealing oil with higher pressure than hydrogen to seal hydrogen. Because the generator rotor shaft must go through the generator end cover, the sealing ring is the key to the hydrogen sealing inside the generator, which can effectively prevent the high-pressure hydrogen leakage along the gap between the end cover and rotor.Core Function of Sealing Bearing
The Sealing Bearing is installed at both ends of the generator shaft and works together with the sealing oil system to form a stable oil film seal. The geometric accuracy and surface finish of the sealing bearing directly affect sealing performance and vibration levels of the unit.
Performance Specifications and Material Properties
YOYIK sealing bearings are manufactured according to strict industry standards to ensure durability and reliability in hydrogen-cooled generators.
| Item | Specification / Feature |
|---|---|
| Applicable Equipment | Hydrogen-cooled generators (Turbine End / Exciter End) |
| Material | High-tin Babbitt alloy (ZChSnSb11-6 / 8-4) or phosphor bronze QSn6.5-0.1 |
| Hardness | Babbitt layer ≥ 27 HB; Base ≥ 80 HB |
| Ovality | ≤ 0.03 mm |
| Surface Roughness | Ra ≤ 0.8 μm (sealing surface) |
| Radial Clearance | According to drawing |
| Operating Temperature | -20°C to 120°C |
| Hydrogen Pressure | 0.1 – 0.6 MPa |
Manufacturing Process and Quality Control
1. Precision Manufacturing Process
- Casting: Ensures no porosity or defects in the base material.
- Rough machining: CNC turning for inner/outer diameters and faces.
- Finish machining: Precision grinding ensures tight tolerances and ovality control.
- Manual scraping: Adjusts oil grooves and contact surface based on shaft size for optimal lubrication.
2. Non-Destructive Testing
- PT testing: Detects cracks and surface defects in the Babbitt layer.
- UT testing: Ensures bonding integrity between alloy and base.
- Full dimensional inspection: CMM measurement ensures accuracy and provides reports.
Installation and Maintenance Guide
Installation Guidelines
| Step | Key Notes |
|---|---|
| Cleaning | Clean bearing, shaft, and housing. Remove debris and check for scratches. |
| Clearance Check | Measure radial clearance (typically 0.20–0.35 mm). Adjust if uneven. |
| Oil Alignment | Ensure oil holes are aligned with the oil supply system. |
| Tightening | Apply correct torque to avoid deformation or loosening. |
| Startup | Start oil system first, then purge air before hydrogen charging. |
Maintenance Recommendations
- Maintain oil pressure difference at 0.03–0.05 MPa
- Monitor oil tank level for abnormal rise
- Check hydrogen purity and refill frequency
- Inspect sealing bearing during shutdown
- Keep oil cleanliness within NAS 7 level
Common Faults and Solutions
| Issue | Cause | Solution |
|---|---|---|
| High hydrogen leakage | Excess clearance or wear | Measure and replace sealing bearing if needed |
| Oil level drop | Internal leakage | Check valve and repair or replace bearing |
| Oil ingress into generator | Excess clearance | Adjust clearance and repair oil deflector |
| High temperature | Small clearance or blocked oil path | Inspect and clean oil passages |
FAQ
Q1: Can turbine-end and exciter-end sealing bearings be interchangeable?
No. Shaft size and structure differ. Always confirm TE or EE before ordering.
Q2: When should a sealing bearing be replaced?
Replace if clearance exceeds 20%, ovality > 0.05 mm, Babbitt damage occurs, or hydrogen leakage exceeds limits.
Q3: How to prevent early wear?
Maintain clean oil (NAS ≤7), avoid long low-speed operation, and monitor oil condition regularly.
Q4: What tests are required after installation?
Oil circulation test, leak test, and monitoring of temperature, vibration, and hydrogen purity.
Q5: Can clearance be adjusted with shims?
No. Shims affect oil film distribution. Replace or repair the bearing instead.
