1. A furnace to burn the fuel.
2. Steam generator or boiler containing water. Heat generated in the furnace is utilized to convert
water in steam.
3. Main power unit such as an engine or turbine to use the heat energy of steam and perform
work.
4. Piping system to convey steam and water.
In addition to the above equipment the plant requires various auxiliaries and accessories depending
upon the availability of water, fuel and the service for which the plant is intended.
The flow sheet of a thermal power plant consists of the following four main circuits :
(i) Feed water and steam flow circuit
(ii) Coal and ash circuit
(iii) Air and gas circuit
(iv) Cooling water circuit.
A steam power plant using steam as working substance works basically on Rankine cycle.
Steam is generated in a boiler, expanded in the prime mover and condensed in the condenser and
fed into the boiler again.
The different types of systems and components used in steam power plant are as follows :
(i) High pressure boiler
(ii) Prime mover
(iii) Condensers and cooling towers
(iv) Coal handling system
(v) Ash and dust handling system
(vi) Draught system
(vii) Feed water purification plant
(viii) Pumping system
(ix) Air preheater, economizer, super heater, feed heaters.
Fig. 4.1 shows a schematic arrangement of equipment of a steam power station. Coal received in
coal storage yard of power station is transferred in the furnace by coal handling unit. Heat produced due
to burning of coal is utilized in converting water contained in boiler drum into steam at suitable pressure
and temperature. The steam generated is passed through the superheater. Superheated steam then flows
through the turbine. After doing work in the turbine die pressure of steam is reduced. Steam leaving the
turbine passes through the condenser which maintain the low pressure of steam at the exhaust of turbine.
Steam pressure in the condenser depends upon flow rate and temperature of cooling water and on effectiveness
of air removal equipment. Water circulating through the condenser may be taken from the
various sources such as river, lake or sea. If sufficient quantity of water is not available the hot water
coming out of the condenser may be cooled in cooling towers and circulated again through the condenser.
Bled steam taken from the turbine at suitable extraction points is sent to low pressure and high
pressure water heaters.