Technical Concept, Objectives and Host Plant
Basis of the COMTES700-project is a general technical concept for a Component Test Facility (CTF) which allows the testing of all major components at affordable costs and which was developed by the power plant suppliers until 2003. The COMTES700-concept is an agreement between suppliers and generators on the requirements of a comprehensive testing programme for materials, financing possibilities and political constraints.
The steam for the testing purpose of the CTF (12 kg/s) is taken from the inlet header of the superheater 1 and is led to the evaporator panel, where it is heated up to 600 °C. Between the evaporator panel and the superheater an injection is foreseen, which can quickly control the temperature level before the test superheater inlet. The steam is heated in the test superheater at 705 °C and will then either enter the high pressure bypass test valve, or will be cooled down at superheater 4 temperature level and mixed with the main superheater steam. In the first case the steam after leaving the high pressure bypass test valve will be cooled down and led to the reheater 1 outlet header.
Figure: CTF Flow Diagram
Thus the CTF allows the testing of the following components:
- Evaporator,
- Superheater tubes,
- High pressure headers,
- High pressure piping,
- High pressure bypass,
- Safety valves.
The objective of the COMTES700-project is to design in detail, manufacture, erect and operate such CTF based on advanced materials. The materials used are T 24, HCM 12, TP 310 N, HR 3 C, Alloy 174, Alloy 617 and Alloy 740.
The testing period of app. 20,000 operating hours has the following focuses:
- manufacturing, bending and welding - also dissimilar - of the materials used,
- in-plant monitoring,
- determination and evaluation of residual service life,
- in-service inspections,
- operational testing of Ni-based alloys for tubes, pipes and valves,
- gaining information on magnetite layer on the rib of internal rifled tubes,
- operational behaviour of all components,
- flue gas corrosion and steam oxidation behaviour of the materials and
- erosion effects due to soot blowing.
The results of the operation of the CTF are evaluated in a special working group and flow back into engineering and design of components to optimise them for the future 700 °C demonstration power plant.
The CTF is installed in the coal-fired power plant Scholven F located
in Gelsenkirchen (Germany). The operating conditions of the host power
plant are a steam temperature of 535 °C and a high pressure of 230
bar. The steam flow of 2,200 t/h produces a net output capacity of 676
MW.