Innovative Low Head Hydro The StreamDiver in Action NWHA Small Hydro Workshop 2016, Wenatchee, WA USA
Agenda 1. StreamDiver Introduction 2. Design Concept and Testing 3. Nussdorf Pilot Plant Operations 4. Summary, Results and Outlook
Worldwide, there is still tremendous potential for the use of low head hydropower for power generation. Decentralized hydropower generation is sustainable, renewable and supports economic development of remote areas. However, decentral, low head power plants have specific requirements regarding commercial viability, availability, maintenance and environmental aspects.
StreamDiver Application Range Covers Heads From 2-8 m (up to 26 ft.) Turbine classification Application by head and flow range The StreamDiver covers the low head, low power range next to conventional designs like Kaplan, Francis or Pelton. StreamDiver application range (single unit) 5 different runner sizes (modules) A single unit generation ranges from below 50 kw up to above 750 kw depending on the available head and flow.
Reduction of O&M Costs is One Key Premise and Today s Focus Reduction of Civil Cost Ease of Project Execution Reduced O&M Cost & Risk Oil-free Plant Solution
Clarity: The Simplified Design of the StreamDiver Ensures the Highest Reliability Standard version: Non-regulated, direct-driven turbine generator unit No dynamic seals, cooling water system, lubrication oil system, excitation system, or runner or guide vane regulation 6 2 1 1 Turbine housing with guide vanes 2 Radial and axial bearing 3 Shaft ends 4 PMG generator 5 Runner 6 Bulb nose 3 4 3 5 2 Generator & terminals Stator vane Runner Housing Shaft, bearing assembly
Two Unique Features are Most Relevant: Bearing Lifetime and Cooling Concept (1/2) Water inlet Heat transfer Lubrication Water flow Heat transfer Water inlet Water flow
Two Unique Features are Most Relevant: Bearing Lifetime and Cooling Concept (2/2) 1. Water exchange Bulb fills with river water before start-up Minimal exchange during operation (minimal sediment exchange) 2. Water circulation Shaft rotation will circulate water in bulb to avoid hotspots Circulation transports heat to the housing elements 3. Heat transfer Discharged flow passes the bulb and housing Passive, convective cooling of the bulb 4. Lubrication River water inside the bulb generates lubrication film Contained sediments are processed by hard coated shaft
Bearing Performance and Lifetime: Endurance Tests at the Test Rig in Heidenheim Test rig assembly and installation Scaled model with same drive-train dimensions Brenz river installation Low head of 2 meter results in relatively low bearing load factor Intermediate measurements of wear (interval of 6 w) Hard-coated surface at shaft, soft shells and pads >18,000 hours of operation Tested with different densities of quartz in bulb 1 1 Due to the high hardness rate (Brinell scale), quartz is considered as most relevant sediment which causes wear of the shaft coat
Results Indicated Wear on Hard Coat with No Significant Correlation with Quartz Density The axial thrust bearing shows most significant wear Degradation of hard coat on thrust ring by a factor of 2.7 compared to radial bearing at the non-driven end (NDE) Relative wear [%] 7.00 3.50 6.00 3.00 5.00 2.50 4.00 2.00 3.00 1.50 2.00 1.00 1.00 0.50 axial bearing radial bearing DE radial bearing NDE 0.00 0 3,000 6,000 9,000 12,000 15,000 18,000 21,000 Quartz content river water << 0.5 g/l Operating hours [hrs] 0,5 g/l 1 g/l 2 g/l Relative wear: Ax 2.7 rad DE 1.7 rad NDE 1.0 NDE DE Weight (drive train) Hydraulic force (runner)
Test Rig Configuration Transferred to Nussdorf Prototype Design Bearing lifetime influencing factors: test rig compared to prototype design Nussdorf (module size SD 13.10) Additional factors: capacity factor (full load hours per year, number of start & stops, ambient conditions (temperatures,...) Factor Test rig Nussdorf Stationary loads 1 different sizes + generator Load factor (hydraulic) Head = 2 m, 7.7 kw Head = 3.6 m, 314 kw Water quality 2 Up to 2 g/l (Quartz) < 0.5 g/l (Quartz) 3 NDE DE Hydraulic force (runner) Expected relative wear (average) Factor compared to test rig Expected lifetime (in years, full load) 75% wear allowed, max. value applied Weight (drive train) Axial 2-3 Radial DE 6-7 Radial NDE 4-5 Axial 16 Radial DE 11 Radial NDE 26 1 Considers design dimensions (bearing distance, clearances, size), stationary loads from drive-train The 2 Due StreamDiver to the high hardness in Action rate (Brinell NWHA scale), Small quartz Hydro is considered Workshop as 2016, most Wenatchee relevant sediment,, WA which USA causes 2016-09-21 wear of the shaft coat 3 Based on assessment report about sediment transport in the Danube river
Prototype in Nussdorf (Austria) Now Completing 4 Years of Maintenance-free Operation Turbine Data: Power Unit: SD 13.10 (Ø 1310 mm) Power: 314 kw / max. 450 kw Net head: 3.58 m / max. 4.68 m Flow: 9.96 cms Generator speed: 333 rpm, 50 Hz Project Status: In operation since August 2012 Operating hours: > 30,000 hrs 1 Exported electricity: > 8.0 GWh 1 On-site inspections: 2 (down: 3 days) Maintenance services: 0 Status: April 2016
Housing After 42 Months of Operation Shows Slight Organic Layer, but Intact Coating Generator leakage test okay, temperature and leakage sensors in function Anti-corrosion coating intact (covered by thin organic layer)
The Stainless Steel Runner is in Excellent Condition and Shows No Notable Abrasion Runner blade condition excellent, no issue with clearances of rotating parts (blade tip, runner housing,...) Guide vane coating intact with some impacts on leading edge
The Power Output Versus Measured Gross Head Per Year The performance of the machine has been stable (constant slope); tendency to have improved over the years (A) (B): Power spread (bias of data for same gross head) mainly influenced by intake conditions (head losses due to pollution level) B A
Temperature Levels in Bulb and Generator Stator Confirm Passive Cooling Concept Generator phase temperature vs. power output Seasonal effects (quarter 1 to 4) A. Delta of 25 C between hottest and coldest period (river water) B. Linear correlation of generator temperature and power Generator phase temperature vs. water temperature in bulb Temperature rise of generator below design value (class F/B) A. Temperature rise of up to ~40 C (design class B: 80 C) A B B A
Measured Wear at the Radial Bearing (NDE) Confirms Projections from Endurance Test Expected replacement of the radial NDE shaft end is required after 23 years (initial projection: 26 years) Replacement is recommended when 25% of the remaining layer is reached extrapolated: 30,000 x 75/11 = 204,000 hours = 23 yrs Wear is not constant over measured profiles on shaft line Relative wear with maximum of 7-11% after 30,000 operating hours Additional sensors detect wear limit for predictable and planned replacement Profile 1 3 2 7 11 %
Summary and Outlook StreamDiver low head technology for heads up to 8 m The innovative design minimizes support systems to maximize reliability Passive cooling concept and bearing design are core features Test and proof of design successful Lifetime projections exceed initial design values Full-scale Nussdorf prototype now goes into its fifth year of operation Full load operation, no maintenance required so far Retrieval and detailed inspection planned after 5 years
Bearing Lifetime Projection and Monitoring: Project Application Band for 50-100 % full load Standard design configuration (SD 7.90 SD 13.10) Recommended replacement at 25% of the remaining hard coat layer Radial NDE Axial Radial DE Application Content of hard particles < 2 g/l (e.g. quartz) Water temperature up to 30 C Maximum wear is monitored: Maximizing lifetime Predictive maintenance Lifetime Projection (Radial DE): Full load 3 m head 8 m head 50% 24 yrs 14 yrs 100% 12 yrs 7 yrs