Supercritical fossil-fired power plant

A supercritical fossil-fired power plant with a once-through steam cycle is usually operated with a sliding pressure the turbine governor valve is kept open in the upper load range and the boiler outlet temperature is kept constant such that the boiler outlet pressure increases proportionally with the steam mass flow and thus with load. Consequently, the boiler is operated at subcritical pressure below approximately 80—90% load. However, such control is not permitted for the SCWR because dryout... 

The basic idea for development of the SCWR is to use the long-term experience of PWRs and BWRs on the one hand, and the experience with supercritical fossil-fired power plants on the other hand, to derive an innovative plant concept with a minimum of research needs. Obviously, the reactor core of such a power plant will be new then, and the core outiet temperatures as well as the enthalpy increase of coolant in the core will exceed by far the current experience. However, all other components of the SCWR power plant, including the steam cycle components and the containment with its safety systems, are not considered to cause any major challenge because the latest fossil-fired power plants are operated even with a life steam temperature of 600°C at pressures above 30 MPa. 

J. Matsuda, N. Shimono and K. Tamura, Supercritical fossil fired power plants design and developments, Proc. SCR 2000, Tokyo, November 6-9, 2000, 79-89 (2000)... 

Appendix A Supercritical Fossil Fired Power Plants - Design and Developments... 

ABWR PWR Supercritical fossil-fired power plant Supercritical watercooled reactor SCLWR-H... 

Table 1.1 Supercritical fossil-fuel fired power plants in USA and Japan...

The Super LWRs can utilize the existing mature technology of the supercritical turbine from supercritical water cooled FPPs, so significant research in this area is not needed. Table 3.2 summarizes the worldwide distribution of fossil-fired supercritical plants. Most new coal-fired power plants are supercritical. Design and developments of supercritical FPPs are introduced in Appendix A of this book. 

In the 1950s, in Japan, the number of large capacity supercritical pressure fossil fuel-fired power plants increased, making good use of rich deposits and cheaply priced imported oil by measure of its scale merit in facility costs, as an alternative to former smaller capacity subcritical pressure fossil fuel-fired plants using domestic coal for fuel. 

Reviews of supercritical fossil-fuel fired power plant technologies and high temperature water and steam cooled reactor concepts in the past are described in the Appendix. 

LWRs were developed 50 years ago. Their successful implementation was based in part on experiences with subcritical fossil-fuel fired power technologies at that time. The number of supercritical FPPs worldwide is larger than that of nuclear power plants. Considering the evolutionary history of boilers and the abundant experiences with supercritical FPP technologies, the supercritical pressure light water cooled reactor is the natural evolution of LWRs. 

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