Steam-power system for the turbing-genra for plant

    The steam-power system consists of a single 1035- MW( e) gross electrical capacity turbine-generator unit, condensing system, condensate polishing and regenerative feedwater heating systems, steam-turbine-driven main feedwater pumps, feedwater and reheat steam preheating equipment, and associated controls, switchgear, station output transformers, etc. All the steampower system equipment, with the exception of the feedwater and reheat steam preheating facilities, is conventional in present-day power stations and will not be described in detail.

    A simplified steam system flowsheet is shown, and some of the principal data are summarized in table S.l. About 7.15 X 106 lb/hr of steam at 3500 psia and 1000° F is delivered to the turbine throttle. The high-pressure turbine exhaust steam is first preheated to 650°F and then reheated to 1000°F before readmission to the intermediate-pressure turbine. The turbine exhausts at 11 /? in. Hg abs to water-cooiP.ci r.()ndPns':"rs. The turbine is indicated on the flowsheet as a crosscompounded unit, but a tandem-compound machine could be used.
    Eight stages of feedwater heating are shown, with extraction steam taken from the high- and low-pressure turbines and from the two turbine-driven boiler feed pumps. The 600-psia, 552°F steam from the highpressure turbine exhaust is preheated to about 650°F in a steam-to-steam U-shell, U-tube type heat exchanger, with steam (at about 3600 psia and 1000°F) from the steam generator outlet entering the tube side and leaving at about 866aF. This exit steam is directly mixed with the high-pressure 551 °F feedwater leaving the top extraction heater to raise the water temperature to about 695°F. Motor-driven canned-rotor centrifugal pumps then boost the water from about 3500 to 3800 psia and 700°F before entering the steam generator.
    A supercritical-pressure steam system was chosen for the MSBR because the 700°F feedwater needed for the steam generator because of the coolant-salt characteristics can be conveniently and efficiently attained through mixing of the supercritical-pressure steam with high-pressure feedwater. Also, the supercritical-pressure system affords a thermal efficiency of 44.4%, as compared with 41.1% for a 2400-psia cycle using a Loeffler boiler principle to attain the 700°F feedwater temperature. Further, the capital cost of a supercritical-pressure system for the MSBR is judged to be about the same as, and possibly less than, the cost of the 2400-psia system.