SXH COATINGS. Successfully combating abrasive wear on hydraulic turbine parts since 1986

Transcription

1 SXH COATINGS Successfully combating abrasive wear on hydraulic turbine parts since 1986

2 The source of the problem Example: Aletsch-Mörel intake water passing the turbine with high concentration of particles (high Mohs hardness) river water 2

3 Damages due to hydro-abrasive erosion Example: Nathpa Jhakri Guide vanes more damages efficiency loss decreased TBO (time between overhaul), longer overhaul duration Runner 3

4 Damages due to hydro-abrasive erosion Effect on energy production minimising the damage The goal of hydropower plants is a continued energy production at low costs and thereby minimisation of down time and repair costs. Possibilities to reduce the impact of hydro-abrasive erosion: Decrease of the particle concentration due to measures in the catchment area and the course of the river due to plant design Desander / Desilter / sand trap Reduction of costs due to erosion by changes to the turbine: Changes of hydraulic design cavitation resistant, better flow conditions, decreasing the relative velocity, better coating suitability (access) Changes in the mechanic design better overhaul possibilities, more stable design/construction Mechanical protection of the components coating with high quality and full robotic 4

5 Factors for a development and application of a successful coating 5

6 SXH TM : Coating at ANDRITZ HYDRO (2012) SXH 70/80 and SXH 7X/8X-Type: WC-CoCr Micro hardness: > 900 HV0.3 (Vickers hardness, DPH 0.3 kg Load) Surface SXH 70 Bonding strength: > 70 MPa (in tensile test, perpendicular to the surface) Base material Surface roughness: as sprayed: Ra = 4-8µm after operation in particle loaded water: Ra = 2-3µm Since 1986: Coating of Runners and other components at ANDRITZ HYDRO : SXH 48 (Cr-oxid basis // Plasmaspray) & different coating developments since 1996: SXH 70 since 2009: SXH 7X (for Pelton runner) Since 2013: SXH 80 and SXH 8X Low resistance against cavitation: Avoid bad flow condition (immediate removal of flow disturbances such as foreign objects, no partial load for Francis and Kaplan) Preferably do not use on components with high cavitation 6

7 SXH TM: Coating at ANDRITZ HYDRO Coating technique, advantages and limitations HVOF Coating (HVOF = High Velocity Oxygen Fuel) Advantages Very good resistance against erosion Tight tolerances High material strength High adhesive strength SXH7X: increased stability of the splitter Limitations Geometrical limitations due to geometry of gun and necessary spray parameters (distance, angle) On-site coating possible but difficult Low resistance against impact Low resistance against cavitation 7

8 ANDRITZ HYDRO SXH TM - Coating Standard Parts: Pelton & Francis Francis Pelton 8

9 Customer benefits due to coating in power plants with erosion Loss in revenue (Loss in production + repairs) Profit Investment without SXH70 with SXH70 overhaul overhaul with coating Amount of particles 9

10 Experience: Pradella (Switzerland), partially coated TBO increase: >3x SXH TM 70 coated Data as per unit: Head Runner diameter D 1 Power Hard Particles Repair after m 1800 mm 75 MW 56% of all particles t after h 10

11 Experience: Pradella (Switzerland), partially coated 92 Influence of the coating surface roughness at the beginning of operations with SXH70 Coating Geometry is retained for a long time Efficiency, % Uncoated Rapid loss of original geometry, therefore increased efficiency loss Efficiency Gain Break-even point depends on the energy price and the type and size of the runner (possibilities of protection) and the amount of hydroabrasive erosion Operation time, h 11

12 Experience: STALDEN (Switzerland), SXH TM 70 TBO increase: x 4 000h h Repair cycle for uncoated runner: - annually: partial repair on site (grinding) - every 2 years: full overhaul Repair cycle for coated runner: - every 4 years: full overhaul including new coating Balance for 2 runner, for SXH70 Investment: Return: cost for coating Avoid cost for 6 partial repairs and 2 full repairs every 4 years Increase of productivity (decrease in efficiency loss) Overhaul with drastically reduced repair cost Data as per unit: Power 46.2 MW Head 1017 m Discharge 5.15 m 3 /s Pitch diameter 2860 mm Nozzles 1 Hard particles 71 % Repair after t 12

13 Experience: Alfalfal (Chile), 2 vertical Pelton units, SXH TM 70 Uncoated after 30'000 tons of sand Coated with SXH TM 70 after tons of sand Coated with SXH TM 70 after tons of sand Data as per unit: Output MW Head 690 m Discharge 13.9 m 3 /s Pitch diameter 2105 mm Nozzles 6 Hard Particles 69 % of all particles Repair after t Intermediate maintenance: worn edges restored by grinding Full overhaul: Coating removed, welding, grinded, heat treatment, application of new coating 13

14 Customer benefit ALFALFAL (Chile): 2 vertical Pelton turbines 14

15 Development for Francis turbines: full coating by robot Fully coated runners since 2009: Nathpa Jhakri: 4 runners Karcham Wangtoo: 8 runners San Fransisco: 2 runners 15 WIK / Sales B_ver 00

16 Experience: Nathpa Jhakri (India): fully coated Uncoated: large damages after 1 monsoon season Data as per unit: Head Runner diameter D 1 : Power Hard Particles Repair after m 4238 mm MW 90% of all particles t Uncoated Uncoated: large damages after 1 monsoon season SXH TM 70 coated: very small damages on two guide vanes after 1 monsoon season Coated SXH TM 70 coated: very small damages in a few locations after 1 monsoon season 16

17 Development for Pelton runners: SXH TM 7X = Better stability of the splitter SXH TM 70: worldwide standard IMG_2465a.JPG SXH TM 7X coated runners since 2010: SXH TM 7X: 20% higher TBO (time between overhaul) Aletsch-Mörel Stalden IMG_2331a.JPG 17

18 Comparison SXH TM 70-SXH TM 80 (WearLab-tests) 18 WIK / Sales B_ver 00

19 Wear Lab - Test Rigs to analyse hydro-abrasive erosion R&D on hydro-abrasive erosion: Fundamental Quantitative influence of parameters Better predictability Design optimisation New coatings Test parameters: Jet diameter: 8-14 mm Jet speed: 30 to 95 m/s Test medium: water/particles (quartz, feldspar, ) concentration up to 50 g/l 19

20 Comparison of damages: prototype - sample Pelton splitter (prototype) Same cross section of sample and prototype identical features of the damages Pelton splitter sample (test rig) 20

21 Dec