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INTRODUCTION—OUTLINE OF SOME DESCRIPTIVE SYSTEMS 3

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4. Condenser. It condenses steam used by the steam turbine. The condensed steam (known
   as condensate) is used as a feed water.


5. Cooling tower. It cools the condenser circulating water. Condenser cooling water ab-
   sorbs heat from steam. This heat is discharged to atmosphere in cooling water.


6. Condenser circulating water pump. It circulates water through the condenser and
   the cooling tower.


7. Feed water pump. It pumps water in the water tubes of boiler against boiler steam
   pressure.


8. Economiser. In economiser heat in flue gases is partially used to heat incoming feed
   water.


9. Air preheater. In air preheater heat in flue gases (the products of combustion) is par-
   tially used to heat incoming air.

1.2. Nuclear Power Plant

Fig. 1.2 shows schematically a nuclear power plant.

Steam

turbine Generator

Steam

Cooling

water

Steam

generator

Water Water

Feed pump

Steam

Coolant pump

Coolant

Hot coolant

Reactor

core

Reactor

Fig. 1.2. Nuclear power plant.

The main components of a nuclear power plant are :

1. Nuclear reactor


2. Heat exchanger (steam generator)


3. Steam turbine


4. Condenser


5. Electric generator.
   In a nuclear power plant the reactor performs the same function as that of the furnace of
   steam power plant (i.e., produces heat). The heat liberated in the reactor as a result of the nuclear
   fission of the fuel is taken up by the coolants circulating through the reactor core. Hot coolant
   leaves the reactor at the top and then flows through the tubes of steam generator and passes on its
   heat to the feed water. The steam so produced expands in the steam turbine, producing work, and
   thereafter is condensed in the condenser. The steam turbine in turn runs an electric generator
   thereby producing electrical energy. In order to maintain the flow of coolant, condensate and feed
   water pumps are provided as shown in Fig. 1.2.