The feedwater pumps increase the pressure of the condensate (~1MPa) to the pressure in the steam generator. Feedwater flow to each steam generator is controlled by feedwater regulating valves (FRVs) in each feedwater line. Thermal Engineering
Schema of a steam turbine of a typical 3000MWth PWR.
From Feedwater Pumps to Steam Generator
The system of feedwater pumps usually contains of three parallel lines (3×50%) of feedwater pumps with common suction and discharge headers. Each feedwater pump consist of the booster and the main feedwater pump. The feedwater pumps (usually driven by steam turbines) increase the pressure of the condensate (~1MPa) to the pressure in the steam generator (~6.5MPa).
The booster pumps provide the required main feedwater pump suction pressure. These pumps (both feedwater pumps) are normally high pressure pumps (usually of the centrifugal pump type) that take suction from the deaerator water storage tank, which is mounted directly below the deaerator, and supply the main feedwater pumps. The water discharge from the feedwater pumps flows through the high pressure feedwater heaters, enters the containment and then flows into the steam generators.
Feedwater flow to each steam generator is controlled by feedwater regulating valves (FRVs) in each feedwater line. The regulator is controlled automatically by steam generator level, steam flow and feedwater flow.
The high pressure feedwater heaters are heated by extraction steam from the high pressure turbine, HP Turbine. Drains from the high-pressure feedwater heaters are usually routed to the deaerator.
Steam Generator – vertical
The feedwater (water 230°C; 446°F; 6,5MPa) is pumped into the steam generator through the feedwater inlet. In the steam generator is the feedwater (secondary circuit) heated from ~230°C 446°F to the boiling point of that fluid (280°C; 536°F; 6,5MPa). Feedwater is then evaporated and the pressurized steam (saturated steam 280°C; 536°F; 6,5 MPa) leaves the steam generator through steam outlet and continues to the steam turbine, thereby completing the cycle.
Isentropic Compression
Isentropic compression (compression in centrifugal pumps) – The liquid condensate is compressed adiabatically from state 1 to state 2 by centrifugal pumps (usually by condensate pumps and then by feedwater pumps). The liquid condensate is pumped from the condenser into the higher pressure boiler. In this process, the surroundings do work on the fluid, increasing its enthalpy (h = u+pv) and compressing it (increasing its pressure). On the other hand the entropy remains unchanged. The work required for the compressor is given by WPumps = H2 – H1.
References:
Nuclear and Reactor Physics:
J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.
U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.
Advanced Reactor Physics:
K. O. Ott, W. A. Bezella, Introductory Nuclear Reactor Statics, American Nuclear Society, Revised edition (1989), 1989, ISBN: 0-894-48033-2.
K. O. Ott, R. J. Neuhold, Introductory Nuclear Reactor Dynamics, American Nuclear Society, 1985, ISBN: 0-894-48029-4.
D. L. Hetrick, Dynamics of Nuclear Reactors, American Nuclear Society, 1993, ISBN: 0-894-48453-2.
E. E. Lewis, W. F. Miller, Computational Methods of Neutron Transport, American Nuclear Society, 1993, ISBN: 0-894-48452-4.
See also:
Turbine Generator
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The system of feedwater pumps usually contains of three parallel lines (3×50%) of feedwater pumps with common suction and discharge headers. Each feedwater pump consist of the booster and the main feedwater pump. The feedwater pumps (usually driven by steam turbines) increase the pressure of the condensate (~1MPa) to the pressure in the steam generator (~6.5MPa).
