Performance Enhancement - Steam Turbine

Answers for energy.

Scope of supplyWhen it’s time to modernize your steam turbine, we know that improving performance at the highest reliability is the top priority. The Siemens BB71 and BB72 modernization is designed to meet this goal. Our fully integrated, monoblock rotor uses an advanced design blade path with an increased annulus area to help increase your plant’s output.

The Siemens BB71 and BB72 LP Turbine modernizations are based on a common, proven design. The replacement LP turbines for both the BB71 and BB72 share the same design features, but vary in blade sizing and staging. The modernized turbines are designated by their nominal annulus exhaust areas: BB71 exhaust area measures 5.6m2, and the BB72 exhaust area measures 6.9m2.

Both LP designs feature:

Fully integral, monoblock rotor

Free-standing design L-0 rotating blades with a nominal 29.5” and 32” blade height and standard side-entry roots of the robust Siemens design. Blade roots are 2 to 3 times larger than original LP turbine blades

Drum stages with rotating blades that are integrally shrouded

Optimized exhaust flow guides

Bladepath seals on integral shrouds are a tip-to-tip design for improved efficiency and long-term thermal performance

Fabricated single-piece inner cylinder (two halves) designed for easier installation and maintenance.

Please note the 5.6m2 modernized turbine also applies to the BB271, BB371 and

Typical LP turbine modernization

BB71 and BB72 (5.6m2 and 6.9m2) LP Turbine Modernization

BB471 variants, and the 6.9m2 modernized turbine also applies to prior BB72 and BB272 variants.

Customer benefitsThe modernization of your LP turbine can be one of the most cost effective ways to improve the long-term performance of your steam turbine plant and to help reduce maintenance costs.

Benefits of the 5.6m2 and 6.9m2 LP turbine modernizations can include:

Increased output

Improved efficiency

Improved integrity and reliability

Improved long-term thermal performance

Reduced maintenance costs

100,000 equivalent operating hours (EOH) outage inspection interval

Optimal installation time

Improved resistance to stress corrosion cracking and high-cycle fatigue

Potential to increase system output without increasing emissions.

For more information, please contact

your local Siemens representative.

Features

Bladed LP rotor

The Siemens advanced monoblock rotor is manufactured from a single forging with no thru-bore. This design significantly reduces rotor body stresses, and boresonic exams are no longer required. Material selection and detailed design features help avoid stress corrosion cracking that may be found on other LP rotor designs in fossil applications.

New, single-piece inner cylinder fabrication

The single-piece LP inner cylinder is con-structed of a combination carbon steel casting and steel plate fabrication split at the horizontal joint. The improved cylinder was designed with the latest finite element tools to help improve reliability and reduce maintenance costs.

Advanced technology blading

Optimized 3-D rotating and stationary blading with enhanced sealing

Integrally shrouded, high-efficiency blading in the front-end stages/drum stages

Free-standing 29.5” and 32” last stage blades, giving an exhaust area of approximately 5.6m2 and 6.9m2

respectively

Leading edges of the LP free-standing rotating blades are flame or laser hardened to help reduce moisture erosion.

Additional features

Reduced exhaust losses

8.7” HgA exhaust pressure limits at high loads

Compatible with existing rotor train to ensure system integration.

Moisture removal features incorporated in the design to minimize erosion.

This improved design has been successfully installed and is in operation.

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Siemens Energy, Inc.4400 Alafaya TrailOrlando, FL 32826-2399, USA

For more information, contact our Customer Support Center.Phone: +49 180/524 70 00 Fax: +49 180/524 24 71 (Charges depending on provider)E-mail: support.energy@siemens.com

Energy Service DivisionOrder No. E50001-D520-A257-X-76USPrinted in USA BU 2009917132620872F IN 0110.2

All rights reserved. Trademarks mentioned in this document are the property of Siemens AG, its affiliates, or their respective owners.

Subject to change without prior notice. The information in this document contains general descriptions of the technical options available, which may not apply in all cases. The required technical options should therefore be specified in the contract.

Fully integrated monoblock rotor features an advanced design blade path with increased annulus area.