The document discusses the theory and evolution of steam generation, highlighting the differences between steam generators and conventional steam boilers. It explains the processes of water boiling and evaporation at different pressures, and the advantages of steam generators such as ease of operation and rapid start-up. Additionally, it presents progress in Rankine cycle power generation with historical data on megawatt outputs and efficiencies over the years.

1. Theory of Steam Generation
Progressive Development of Power Generation through
Steam Generation……

2. The Theory of Producing Steam
• Water boils and evaporates at 100°C under atmospheric pressure.
• By higher pressure, water evaporates at higher temperature - e.g. a
pressure of 10 bar equals an evaporation temperature of 184°C.
• During the evaporation process, pressure and temperature are
constant, and a substantial amount of thermal energy is used for
bringing the water from liquid to vapour phase.
• When all the water is evaporated, the steam is called dry saturated.
• In this condition the steam contains a large amount of latent heat.
• Further heating of dry saturated steam will lead to increase in
temperature of the steam.
• Superheated steam.

3. Steam generator versus steam boiler
• Opposite the principle of the steam boilers, the water in the
steam generators evaporates inside the tube winded up into
serial connected tube coils.
• The feed water is heated up to the evaporation temperature and
then evaporated.
• The intensity of the heat, the feed water flow and the
size/length of the tube are adapted, so that the water is exactly
fully evaporated at the exit of the tube.
• This ensures a very small water and steam volume (content of
the pressure vessel).
• Thus there are no buffer in a steam generator, and is it
temporary overloaded.
• The advantages using a steam generator compare to
conventional steam boilers.

4. • Easy to operate - normally no requirement for boiler
authorisation
• Rapid start-up and establishing full steam pressure Compact
and easy to adapt in the existing machinery arrangement
• Price attractive - especially at low steam rates.
• The advantages using a steam generator compare to
conventional steam boilers:
• Easy to operate - normally no requirement for boiler
authorisation
• Rapid start-up and establishing full steam pressure Compact
and easy to adapt in the existing machinery arrangement
• Price attractive - especially at low steam rates.

5. Progress in Rankine Cycle Power Generation
Year 1907 1919 1938 1950 1958 1959 1966 1973 1975
MW 5 20 30 60 120 200 500 660 1300
p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 15.9 24.1
Th
o
C 260 316 454 482 538 566 566 565 538
Tr
o
C -- -- -- -- 538 538 566 565 538
FHW -- 2 3 4 6 6 7 8 8
Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1
,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40

6. Steam Generation Theory
• Within the boiler, fuel and air are
force into the furnace by the
burner.
• There, it burns to produce heat.
• From there, the heat (flue gases)
travel throughout the boiler.
• The water absorbs the heat, and
eventually absorb enough to
change into a gaseous state -
steam.
• To the left is the basic theoretical
design of a modern boiler.
• Boiler makers have developed
various designs to squeeze the
most energy out of fuel and to
maximized its transfer to the
water.