DynaVec AS | LIV-bygget | N-7125 Vanvikan | Tel+ 47 934 63 700 | epost | Norway

Innovative Pelton runner with exchangeable buckets as spare parts.

Pelton

The Dynavec Pelton runner consists of separate disk and the optimal number of replaceable buckets connected to the disk each by one bolt only. This gives the opportunity for easier access to fully apply hard coating (HVOF) at the wetted surfaces and the possibility of easily exchanging the buckets (spare parts).

Introduction
Flow analysis

The bucket design is performed by an in-house program for the lay-out of the bucket, both inside and outside.  After the layout, the performance is evaluated by a two-phase transient CFD calculation. The design as e.g.  angles at the inflow, outflow, depth and width of the bucket are changes to get the best performance over the entire operation range.

The bolted pelton runner from DynaVec can easily be assemble and disassemble by standard hand tools. This can easily be performed at site if a lifting arrangement is present. A customized assembly procedure will follow each delivery.

As the buckets can be removed, all wetted surfaces can easily be HVOF coated. The thermal spray coating (HVOF - High Velocity OXY-Fuel) is applied with robots. Typical coating thickness will be between 0.2 – 0.3 mm.

Maintenance
Value proposition
  1. Buckets as spare parts/replaceable

  2. Easy cost effective manufacturing of buckets

  3. Possibilities to apply coating easier and more successful

  4. Extended lifetime of disk (no impact of thermal stress forced by welding)

  5. No impact of thermal stress forced by welding. No heat treatment to remove the thermal stress

  6. Easy maintenance of bucket vs. traditional

  7. Both for new turbines as well as the refurbishment market

Finite element analysis

The runner will be analysed using modern Finite Element Analysis (FEA) to ensure a safe operation of the runner.  The worst condition at maximum torque and early / late interaction of the water jet on the bucket and support are analysed to keep the dynamic stresses below the design criteria. In addition the centrifugal forces both at nominal speed and runaway speed are evaluated.

Assembly and disassembly
Coating

There are two types of maintenance for the bolted pelton runner. The most efficient is the preventive maintenance  where sandblasting and recoating are performed before the coating surface is broken.

The alternative is to reshape the geometry if it is damaged before coating as normally in a planned maintenance schedule. Since the bolted runner can easily be disassemble this will simplify the maintenance and repair compared to a welded runner.