Our specialist team is conducting routine maintenance on the Kaplan power plant.

Due to the characteristics of Kaplan turbine units, which primarily involve double regulation of guide vanes and runner blades, making them suitable for low-head, high-flow conditions, our maintenance focus revolves around specialized components such as blade seals/operating mechanisms, dual linkage systems, water guiding mechanisms, and main shaft seals, while also covering conventional hydraulic, electrical, and governor system maintenance.

Core Procedures:

Shutdown and dewatering → Draft tube dewatering and air purging → Runner lifting → Blade disassembly → Operating mechanism (servomotor, connecting rod, pivot) maintenance → Seal replacement → Blade reassembly and commissioning → Runner static balance test → Lifting and positioning

Key Maintenance Points:

Blade Seals: Replace radial seals + end face seals (commonly using fluororubber/nitrile rubber parts), inspect seal groove wear, repair scratches by welding (depth ≤0.2mm) to prevent excessive water leakage during operation;

Blade Pivot: Check journal roundness, cylindricity, surface roughness Ra≤0.8μm, no corrosion or pitting; repair excessive clearance by hard chrome plating;

Runner Internal Operating Mechanism: Check servomotor piston and cylinder wear, connecting rod pin bushing clearance (≤0.15mm), clean hydraulic pipelines, replace filter elements to prevent jamming leading to blade adjustment failure;

Static Balance Test: Perform static balance after the runner is lifted out, remaining unbalance ≤ design value (generally ≤50g·m), to prevent excessive vibration during operation.

Quality Standards:

After blade seal installation, perform a 0.5 times working water pressure leakage test; no significant leakage within 30 minutes;

Blade opening/closing synchronicity ≤1°, uniform clearance between blades and runner chamber when fully closed (circumferential deviation ≤0.5mm);

Operating mechanism operates flexibly without jamming, and the blade adjustment range meets the design requirements (generally -5°~+25°). 2. Water Guiding Mechanism Overhaul

Core Procedures

Guide vane full closure and locking → Guide vane clearance measurement → Guide vane bushing/connecting rod overhaul → Guide vane seal replacement → Servomotor overhaul → Clearance adjustment and locking

Key Overhaul Points

Guide vane clearance: Measure the vertical clearance + end face clearance. For Kaplan units, due to the large flow rate, the vertical clearance needs to be adjusted for each vane, and the cumulative clearance should be ≤0.1mm/m (guide vane height);

Guide vane bushing: Check the wear of the copper bushing. Replace if the clearance exceeds the limit (single side ≥0.2mm). Ensure the bushing is pressed in without loosening, and the grease is fully filled (molybdenum disulfide lithium-based grease);

Guide vane seal: Replace the rubber water stop strip to prevent water leakage from the spiral casing leading to water accumulation after shutdown;

Water guiding servomotor: Check the piston seal and cylinder inner wall for scratches. Test the servomotor's operating speed (should conform to the governor system design, generally 5-10s for opening and 3-5s for closing).

Quality Standards

After the guide vanes are fully closed, and the spiral casing is filled with water to the working head, there should be no significant leakage from the guide vane vertical surface;

The synchronization of guide vane opening/closing should be ≤2°, the servomotor should have no external leakage, and the oil pressure drop after 30 minutes of pressure holding should be ≤0.1MPa. 3. Main Shaft Seal and Bearing Overhaul

Core Procedures

Main shaft seal disassembly → Seal replacement → Bearing (guide bearing / thrust bearing) inspection → Oil quality testing / replacement → Clearance adjustment → Seal testing

Key Overhaul Points

Main shaft seal: Kaplan units mostly use face-contact seals/water pump seals; replace the rotating ring/stationary ring and sealing O-rings; check the flatness of the sealing surface (no scratches or pits); rotating ring runout ≤ 0.05mm;

Guide bearing: Check the wear of the Babbitt metal bearing shells; the alloy layer should be free of peeling and cracks; adjust the bearing clearance to the design value (generally 0.1~0.2mm);

Thrust bearing: Check the accuracy of the bearing temperature measurement points; check the contact between the thrust head and the thrust plate; the surface roughness of the thrust plate Ra ≤ 0.4μm, and free from corrosion.

Quality Standards

The main shaft seal undergoes a working water pressure test; no leakage within 30 minutes; the seal leakage rate during operation ≤ design value (generally ≤ 10L/min);

Bearing oil temperature is stable at ≤ 65℃; no abnormal noise from the bearings; vibration value ≤ 0.03mm (double amplitude).