Materials for High Temperature Power Generation and Process Plant Applications PDF

Marked improvements in both the unit size and the thermal efficiency of steam turbines have occurred over the last forty years. To a large degree this has been the direct result of advances in the available size, quality and mechanical properties of the forgings and castings from which the most critical components are manufactured. The typical unit size in the 1950s was about 100 MW whereas fossil-fired units currently being tendered can develop as much as 1000 MW and nuclear powered units up to 1500 MW from one single line machine. Over this period the thermal efficiency of fossil-fired units has been improved from 30% to 49%. This increase in the efficiency of fuel conversion not only provides economic benefit but also serves to reduce power station emissions, a 1% efficiency increase of a 680 MW unit resulting in a lifetime reduction of some 0.8 million tonnes of carbon dioxide. The improvements in unit size and efficiency have been achieved by advances in the steam conditions from 100 bar/SOO°C to 300 bar/600°C, made possible by the improved high temperature strength of available alloy steels, and technological progress in the manufacture of large forgings and castings.

The metallurgical developments underpinning these advances have been in a variety of disciplines which include steelmaking, forging, heat treatment, foundry technology, alloy design and fabrication processes.

Edited by: A. Strang