Services for Steam Turbine SST-200
General Information
- Description
The SST-200 is a single-casing steam turbine in a packaged base frame-mounted design. Developed to achieve high efficiency for generator drives combined with high reliability for mechanical drives, the SST-200 is characterized by easy handling.
For SST-200 steam turbines, Siemens feature a major portfolio of service solutions and products to help optimize efficient plant operation.
This service can include:
- Performance Maintenance
- Performance Enhancement
- Service Programs
- Product-Related Services
- Training and Consulting
Our Portfolio (2)
Replacement of Guide Blade Spacers
- Background
- Benefits
- Scope Considerations
In the past, spacers were used to secure the guide blades made of section material in the groove in the guide blade carriers with the requisite spacing. Production and installation of the spacers matched to the blade contour and fitted in the groove were complex processes and required a great deal of manual work and expertise (Fig. 1). Thanks to the advances made in production technology these spacers can be replaced with simple rings in which the blade contour is EDM-machined.
The profile contour of the guide blades is machined into the chromium steel rings by means of EDM. The blades are then inserted and pinned in the machined hole (Fig. 2). The guide blade half-ring fitted with the blades is inserted in the guide blade carrier groove and secured by locking in the joint (Fig. 3). Installation, riveting of the shrouds and finish-turning are performed – as in the past – after installation of the guide ring in the guide blade carrier.
Benefits can include:
- No manual fitting-up work when fitting the blades
- To minimize flow losses the leading edges of the guide-rings are optimally rounded and the guide ring / blade clearances reduced.
- If the steam path necessitates it, the guide rings can be readily designed with expansion bevels.
- If required, the guide ring can be provided with integral cover plates for the guide blade carrier inner diameters as protection against erosion-corrosion (Fig. 4).
- The blade pitch remains constant at the joint, which can help avoid additional excitation forces acting on the subsequent moving blades.
- The holding groove at the guide blades is no longer required.
- The chromium steel guide rings are resistant to erosion-corrosion in the saturated steam regime.
- In the saturated steam regime simple ducts can be provided on the EDM rings for condensate drainage.
- On replacement of the spacers with EDM rings the axial and radial clearances remain unchanged, meaning that fit-up work on the rotor can be avoided.
- The EDM hole contour can be matched to virtually any blade profile shape.
- In the event of replacement of EDM rings with guide blades the disassembly and reassembly work required is reduced.
Scope of retrofit considerations:
- The guide-rings should preferably be installed in a Siemens workshop. If necessary machine tools are available, it may also be possible for installation to be performed on site by Siemens personnel.
- The grooves in the guide blade carrier need to be remachined appropriately to accommodate the EDM rings and the shrouds finish-turned after riveting.