Martin Stapper

Successful Power Limit Increase Testing of SGT5/6-2000E Gas Turbines on the Basis of Si3D Turbine Blading

One of the most innovative solutions for making SGTx-2000E gas turbines more competitive and more cost-effective is the Si3D upgrade product. The profile of the Si3D turbine blades and vanes is aerodynamically optimized. Based on this new Si3D design optimization, a Power Limit Increase (PLI) upgrade was developed in close cooperation with customers. The Power Limit Increase upgrade is a change of the engines rating which allows operating the engine at a higher maximum electrical power output. The PLI not only shows a much higher power output of up to 16 % but also a significant increase in efficiency at low ambient temperatures — especially for district heating power plants.In 2011/2012 at a Finnish SGT5-2000E an opportunity arose to carry out an extensive program of measurements for testing and validating how the power limit can be increased in parallel with the blading upgrade (no compressor modification). The essential feature of this campaign was a non-intrusive stress measurement of blade vibration by means of optical probes. The campaign was successfully completed, and the Finnish customer is able to take advantage of optimized winter operation. The main benefit is operation of the engine at base load, especially at very low ambient temperatures with a higher power output and efficiency potential. On the basis of these encouraging results, Siemens prepared a fleet release for a power limit increase of all SGT5-2000E gas turbines with Si3D airfoils in stages 1 to 4 from 173 MW to 186 MW (with compressor mass flow increase) or even up to 196.5 MW.In addition, a second opportunity arose 2013 to execute the similar test campaign in the USA for the 60 Hz Si3D turbine blading with a compressor mass flow increase. Thereby not only the same test equipment was used, but several additional investigations had to be done prior to the test campaign.This publication describes details of the technical evaluation and conversions required to perform these tests and accomplish an increase of the power limit of the SGTx-2000E fleet.Copyright