Abstract

The worldwide demand for electricity is continually increasing. Deregulation in the power generation business is driving rapid changes in the global energy market. This results in higher premiums on steam turbine efficiency and opportunities to structure several new Steam Turbine products to meet these challenging requirements. The “Dense Pack” high pressure section replacement and offering is one of the newest advanced designs to address these needs by delivering more power for the least amount of fuel. The intense competition to serve the electric power utility industry combined with the drive for new product introductions to be of the highest development life-cycle quality demands that verification of performance benefits be established very early in the new product development process.

To answer this and establish pre-field installation credibility with customers, a new multi-stage Steam Turbine Test Vehicle (STTV) has been designed and constructed. The turbine faithfully models a typical, 4-admission, large utility steam turbine and preserves geometric and flow similarity while operating at reduced pressure. The basic train is comprised of a nominal 3.5 MW (4700 hp) test turbine, a 5:1 speed reducing load gear, and two tandem 3.0 MW (4000 hp) dynamometers. The thermodynamic cycle is straight through superheated steam entering the turbine through a turbine bowl pressure regulator control valve and exhausted to the atmosphere via a back pressure control valve and roof-mounted silencer. A rigorous Design for Six Sigma (DFSS) process was used to establish the test turbine facility and to ensure all of the new product program objectives were met.

A detailed description of the facility is given with discussion of the major sub-systems, prototypical model hardware, unique steampath instrumentation, and the test procedures used to ensure accurate, repeatable data. The timeline for accomplishing the design, construction, and early testing is chronicled. Key test results are summarized including baseline testing to validate the new test facility, testing of the “Dense Pack” aerodynamic design methodology for power generation steam turbines, and the performance evaluation of developments such as new shaft, advanced aerodynamics and bucket tip seals.

In addition to developing the new design technologies and verifying their predicted efficiency increases, the Steam Turbine Test Vehicle is key for conducting Form-Fit-Function studies. Model hardware built using the standard manufacturing methods and materials intended for production parts provides invaluable insight ahead of finalizing production specifications. New features such as advanced seals and Integral Cover Buckets (ICB) benefit from being more thoroughly understood in terms of assembly and procedures ahead of new product production.

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