6. HYDRO-MECHANICAL EQUIPMENT The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka 6. HYDRO-MECHANICAL EQUIPMENT The outline of the site survey results for hydro-mechanical equipment is as follows. Also, attached are the main features for the hydro-mechanical equipment. Wimalasurendra Old Laxapana Canyon Equipment Hydropower Station Hydropower Station Hydropower Station Penstock No significant defects No significant defects Leakage from expansion Repair for the remote joints control of the penstock valve Spillway Plan for regulating the Plan for regulating Installation of accesses spillway gates spillway gates to anchorage Intake Repairing the intake No significant defects Plan for intake air valve equipment by CEB modification Bottom outlet CEB Plans for repairing No significant defects No significant defects the needle valve Tailrace No significant defects No gate Repairing the tailrace gate by CEB Other - - - New Laxapana Polpitiya Equipment Hydropower Station Hydropower Station Penstock Repair the drain and Touch up painting for passages corroded portions Spillway Installation of accesses Touch up painting to anchorage Drain holes at gate leafs Installation of accesses to anchorage Plan for a dam control system Intake Plan for Raking Plan for Raking machine machine Bottom outlet No significant defects No significant defects Tailrace No gate No significant defects Other Plan for Removing Plan for Removing sedimentation sedimentation Final Report 6 - 1 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka Table 6.1 Main Features of Hydro-mechanical Equipment Power Station Wimalasurendra Old Laxapana Canyon New Laxapana Poipitiya Capacity(MW) 25 × 2 10 × 5 30 × 2 50 × 2 37.5 × 2 Completion Date 1965 Stage I, 1950 (54years) 1983 1974 1969 (39years) Stage II, 1958 (21years) (30years) (35years) (46years) Reservoir Castlereagh Reservoir Norton Pond Maussakelle Reservoir Canyon Pond Laxpana Pond Storage capacity (103m3) 59,700 394 14,714 92 202 Usable capacity (103m3) 53,583 245 107,929 629 113 Dam Concrete Gravity Concrete Gravity Concrete Gravity Concrete Gravity Concrete Gravity Length (m) x Height (m) 236.8 × 47.2 103.0 × 28.7 187.5 × 41.1 182.9 × 27.4 137.2 × 29.6 Headrace Tunnel Length (km) 6.1 2.6 4.1 5.6 7.7 Penstock Type Welded, Ring support Spigot & socket, Ring Welded, Ring support Welded, Saddle support Mechanical joint, (wheel) support (wheel) (slide) (concrete) Saddle support (steel) Lines 2 4 2 2 2 Length (m) 887.7 1,527.4 823.0 1,889.8 603.5 Diameter (m) 1.98 (78in) 1.22 (48in) 2.51 (99in) 1.68 (66in) 2.29 (90in) Design head (m) (227.4) (472.4) 314.5(204.2) 724.8(541.0) (259.1) Material JIS SM50 9.5 – 28.5mm ASTM A537 CL1 SELCO 56CN CASG 40.8 Grade B Design thickness 17 – 23mm SOUTH DURAHAM 12 -24mm 8 – 31mm 18 -27mm Fabricator SAKAI IRON WORKS STEEL & IRON B.V.S-JONNERET GIOVANOLA FREES SWITZERLAND S.A Penstock Guard Valve Penstock valve Penstock valve Tunnel inlet valve Penstock valve Penstock valve Penstock valve Flow (m3/s) / line 14 2.1 (Stage I) 18 11.5 17 3.25 (Stage II) Final Report 6 - 2 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka Power Station Wimalasurendra Old Laxapana Canyon New Laxapana Poipitiya Capacity(MW) 25 × 2 10 × 5 30 × 2 50 × 2 37.5 × 2 Spillway Gate Type Natural spillway Natural spillway Radial Gate Radial Gate Radial Gate Quantity Flash board 4ft × 14 3 2 3 Width (m) x Height (m) 10.7 × 4.6 12.2 × 8.8 10.7 × 7.3 Hoist Wire rope type Wire rope type Wire rope type Design flood Max. Flood level Max. Flood level Max. Flood level Max. Flood level Max. Flood level 1096.4m 870.2m 1170.43m 963.17m 381m Intake Equipment Intake Gate Intake Service Gate Sliding gate Stoplogs (wooden) 1-Roller Gate Fixed wheel gate Fixed wheel gate Width x Height 1.83m × 4.42m 4.11 m × 4.72 m 3.2m × 3.2m 4.11m × 4.72m Hoist Overhead gantry crane Electric motor Intake Guard Gate Roller gate Width – 2.06m 1-Slide Gate Bulk head gate Fixed wheel gate Width x Height 1.83m × 3.96m 3.2m × 3.2m 4.11m × 4.72m Hoist Intake Trashrack Rotary screen Moving Glory type Fixed screen 03 Nos. Fixed screen 2.44m × 4.57m 2.33m × 5.94m × 03 Raking Machine No By high pressure water No No No spraying Bottom Outlet Works Hydraulic-operated Stoplog gate – 02 nos Hovel bunger valve 1.525m × 2.135m Fixed wheel gate Needle valve Lifting by chain blocks D=2.43m Control gate Electric motor D=1.5m 1.525m × 2.135m Emergency gate Guard gate Fixed wheel gate Final Report 6 - 3 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka Power Station Wimalasurendra Old Laxapana Canyon New Laxapana Poipitiya Capacity(MW) 25 × 2 10 × 5 30 × 2 50 × 2 37.5 × 2 Tailrace Gate Type Slide Gate No Slide Gate No Slide Gate Quantity 2 2 2 Width x Height Overhead gantry crane Hoist for stoplog gate Monorail hoist Separate electric motor driven and bulk head gate Other Trashrack placed inside Hydro-mechanical of the intake with grab Equipment mechanism Remarks Intake gate & structures There is a pipe piece in completely repaired between the dam and the tunnel. Nearby the dam there is a butterfly valve. According to the reports, this intake has been designed for only one machine Final Report 6 - 4 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka Attached are the rough rehabilitation costs for the hydro-mechanical equipment. Table 6.2 Rehabilitation Work Cost of Hydro-mechanical Equipment Hydropower Cost Estimate Rehabilitation Item Station (103 US$) Wimalasurendra New spillway gate(SR gate) Width 9.1m × Height 1.2 m 14 nos. 5,600 Old Laxapana New spillway gate(SR gate) Width 9.1m × Height 1.2 m 8 nos. 3,200 Repair for remote control at penstock valve 200 Canyon Improving the air valve of the intake valve (an anti-negative pressure valve) 300 Change the air valve position New Laxapana Intake Trash rake machine 500 Polpitiya Intake Trash rake machine 500 Common Removal Sedimentation of Canyon & Laxapana reservoir 3 Dredging grab 1m 100 Mobile crane 30t 300 Dam control system of Canyon & Laxapana 600 Robot for repainting the inside penstock Blasting machine & Painting machine 1,500 Equipment for outside repainting machine Blasting machine & airless spray 200 Consulting fee 1,300 Contingency 1,400 Total cost 15,700 (Note) The purchase of the robot for repainting the inside penstock will be discussed by CEB due to the expensive. Final Report 6 - 5 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka 6.1 Wimalasurendra Hydropower Station 6.1.1 Site Survey (1) Penstock The exposed outer surface of the penstock was visually inspected for excessive leakage, corrosion, pitting, coating deficiency, etc. <Appearance investigation> The penstock’s exterior was visually inspected while the penstock was under full pressure in order to observe any leakage. Deformation of steel pipes, loosed bolts, anchor blocks and concrete saddles were visually inspected. <Plate thickness measurements> The shell plate thickness of the steel penstock was checked using an ultrasonic thickness meter at the mean of the anchor blocks. <Vibration measurements> Vibration of the steel penstock was checked using a vibration meter at the mean of the anchor blocks. <Painting film thickness measurements> Painting film thickness was checked using an electromagnetic coating thickness meter at the mean of the anchor blocks. Table 6.3 Measurement Instrument Measurement instrument Type Model Plate thickness Ultrasonic 0.1mm JFE TI-50K Vibration Digital Showa Model 1332A Painting film thickness Electromagnetic Sanko SDM-3000T (2) Gate and Trashrack The gates and trashracks were visually inspected. 6.1.2 Penstock (1) Present Status The penstock was constructed in 1965 and has been in peroration for more than 39 years. No serious problems have been observed so far. The penstock is 887.7m long and extends from the penstock valve house to the powerhouse. General penstock data are as follows. Final Report 6 - 6 The Follow-up Study on the Rehabilitation of Hydropower Stations in the Kelani River Basin for The Study of Hydropower Optimization in Sri Lanka Type : Welded type, Ring support with wheel No. of Penstock : 2 Length : 887.7m Diameter : 1.980 – 1.600m Design head : 227.4m (static design head) Material : JIS SM50 Design thickness : 17 – 23mm Picture 6.1 Panorama view of penstock Picture 6.2 Ring girder support with wheels The collected data of the plate thickness for the penstock were consistent and reasonable. According to the data, there was no significant loss in metal due to corrosion. Also, there were no significant vibrations in the penstock. More specific information can be found on the attached checklist. (2) Rehabilitation plan May not be necessary 6.1.3 Flashboard of Spillway (1) Present Status The spillway was designed as an ungated ogee crest with 14 bays that are 9.1m in width. A 1.2m flashboard system was installed in the dam crest. This flashboard system was designed by Preece Cardew in 1982.