Macek Power has more than 25 years of steam turbine rerate experience
Few non-OEM options in the world combine steam turbine engineering and component part manufacturing capability in one place. Macek Power offers the convenience and value of both as a single supplier to steam turbine parts buyers.
Steam Turbine Rerates and Redesign
Macek Power typically completes two to three steam turbine rerate projects per year. Company owner and General Manager, Michael Macek, has been rerating steam turbines for more than 25 years. Whether to increase efficiency, improve reliability, achieve greater power, suit a new application, or accommodate changed operating conditions, the steam turbine rerate involves the following steps:
- Acquisition of existing steam path geometry
- Development of computer model for performance simulation
- Performance simulation and evaluation of results
- Steam path redesign
- Iteration
Steps 3 and 4 often must be repeated, as design influences such as rotordynamics, structural mechanics, thermodynamics, and manufacturing cost will conflict with each other. For example, the thermodynamically optimum shaft speed may not be compatible with damping coefficients provided by fluid film bearings. Consequently The steam turbine rerate sometimes requires new component manufacturing. With experience on turbines ranging in capacity from several hundred kilowatts to 500 MW, Macek Power is a sensible choice for steam turbine rerates, performance evaluation, efficiency improvement, and application engineering.
The Illustrated Steps
The first step in the steam turbine rerate process is to obtain steam path geometry, which can be done manually with precision and semi-precision measurement tools for small turbines, or digitally, for larger turbines that feature varying cross-section stator and rotor blades. The image to the left shows digital-method reverse engineering in progress.
After acquiring original geometry, the next step in the steam turbine rerate process is to develop the computer model, The computer model specifies both steam path geometry and boundary conditions including shaft speed, extraction flows, and steam states. . A 35-MW extraction-condensing steam path model (rotating elements) is shown here.
The third steam turbine rerate step simulates thermodynamic performance using either in-house developed or commercially available the software. A myriad of model parameters related to geometry, steam conditions, extraction flows, shaft speed, and running clearances can be varied to study effects on performance. The image to the left illustrates select results of a single stage, including enthalpy drop, velocity triangles, and efficiency.
The final step in the steam turbine rerate process is redesign, which is usually iterative because of the many factors that influence design. The rerate may be as simple as removing stages from the steam path and/or reducing stationary flow area, or it could be as involved as complete replacement of the original steam path. The image above shows redesigned rotor blades installed into the submerged arc weld-reconstructed wheels of an integral rotor.