A full-scale turbine control valve was selected for COMTES700 as a steam turbine test component. It is integrated into the Component Test Facility (CTF) for the exposure to steam conditions of 212 bar and 705 °C at 12 kg/s. The COMTES700 Turbine Valve is a separate R&D project and is financed by a group of European Power Generators and the suppliers Siemens and Alstom without public sponsorship.
The main steam control valve was selected because it is one of the most critical components of a 700 °C turboset. It has both high safety relevance and high loading due to internal working pressure at a high metal temperature which is close to the main steam temperature.
Due to the fact that the heat transfer at supercritical steam pressure in the CTF is nearly independent from steam velocity and mass flow, the stationary and transient metal temperatures of the COMTES700-Turbine Valve will be the same as for full load conditions. Thus, the thermomechanical loads for valve casing and internals will be representative for those of other 700 °C steam turbine components.
The valve has a weight of 4 tons and is positioned lying flat on its side. It is a proven design which would be used in turbosets up to 600 MW. The material selection for the valve was made by both suppliers cooperatively. Further, Siemens and Alstom cooperate in manufacturing and testing.
In the interest of optimal quality assurance, E.ON Engineering as well as the Rheinisch Westfalian TÜV and MPA Stuttgart have been involved in material evaluation, mechanical design and component inspections. A material test program which has been started in advance will evaluate long-term properties parallel to the component test.
During its planned test operation from July 2005 to June 2009, the measurement of metal temperatures, deformations and strains will be carried out. In agreement between host plant and the suppliers, shutdowns of the block will be used for inspections. After the test phase the valve components will be destructively tested.