Single Crystal Materials for Advanced IGT Application

摘要

Large gas turbines now have firing temperatures in excess of 1425°C(2600°F). Burning fuel at these temperatures provides combined cycle efficiencies near 60% with very low emissions. The good news is that future generations of these engines will exceed 60% and help with global energy supply issues. Technologies associated with this higher firing temperature are arbitrarily called "H". The most economical use of these turbines is to run them at base load for very long times to take advantage of their high efficiency. Earlier technologies, called "E" or "F" had lower efficiencies and firing temperatures. Figure 1 summarizes these trends. Most E and F units use directionally solidified (DS) materials as buckets and nozzles as their most capable materials. Taking power turbines to new extreme conditions requires an upgrade from DS to single crystal (SX) substrates. Some of the background and challenges of the journey will be discussed with emphasis on the step change in improved performance for SX components.