Steam power plant content arrangement efficiency advantages disadvantages
comparison with diesel engine powered vessels basic glossary main elements of
a steam power plant auxiliaries the arrangement mechanical power is produced
by a heat engine that transforms thermal energy from combustion of fuel into
rotational energy heat generated in the furnace is transmitted to the boiler
where water forced into the boiler by the feed pump is converted into steam
the arrangement steam drives turbine blade shaft efficiency the efficiency of
a steam turbine is limited by the maximum temperature of the steam
produced and is not directly a function of the fuel used for the same steam
conditions coal nuclear and gas power plants all have the same theoretical
efficiency advantages of SPP low noise low weight little or no vibration
relatively easy and simple plant maintaining and handling cargo in a
suitable form of energy can be used to make steam can be used as bunker fuel
onboard LNG and LPG carriers disadvantages of SPP higher specific
fuel consumption however reheating less efficient than reciprocating engines at
idle speeds comparison with diesel engine powered vessels diesel engines
steam propulsion most efficient prime mover
lower fuel consumption less Bunker space more expensive to build and maintain
more noise and vibration heavier less efficient than reciprocating engines at
idle speeds higher specific fuel consumption cargo can be used as bunker
fuel onboard LNG and LPG carriers relatively easy and simple plant
maintaining and handling low noise little or no vibration low weight basic
glossary operating pressure boiler efficiency steaming hours heating
surface generating surface superheat esteem basic glossary operating pressure
the pressure at which the boiler is operated in surface boiler efficiency of
the ratio between the thermal energy actually absorbed by water and the
thermal energy available and fuel 80 to 90 percent basic glossary steaming hours
the time during which the boiler generates steam heating surface the
total surface of all parts exposed to combustion gases tubes superheater
economizer basic glossary generating surface a part of the surface in which
water is heated and steam is generated drum superheated steam equals saturated
steam plus more heat at constant pressure - greater than dry steam to
avoid damage to turbine blades
main elements of SPP furnace boiler superheater
turbine condenser furnace a chamber in which heat is produced combustion of
fuel and generation of hot gases burners brake fuel into fine particles to ensure
efficient combustion boiler steam generator saturated and superheated
steam steam drum a reservoir of water / steam at the top end of the water tubes
it acts as a separator for the steam / water mixture a difference in densities
water circulation natural or forced boiler boiler water tube boiler firetube
boiler firetube boiler hot gases passed through the tubes feed water surrounds
them water tube boiler steam and water circulate through small diameter tubes
and drum gases of combustion path surround them more commonly used lighter
occupies less space and has increased efficiency higher pressure and
temperature water tube boiler
superheater consists of headers and superheater tubes converts saturated
steam into dry steam turbine steam is admitted to the turbine heat energy is
converted into mechanical energy useful work high-pressure turbine low-pressure
turbine condenser heat exchanger tubes sea water steam water condensate the
vacuum is created due to steam condensate volume difference vacuum is
maintained by constant cool water circulation through the tubes condenser
auxiliaries condensate collecting tank hot well main condensate pump air
ejector garrotting feed tank make up tank emergency feed tank feed pump
economizer main condensate pump condensate collecting tank hot well to
pump water from the hot well through the main area to the dairy tank feed tank
air rejecter no moving parts jet pump Bernoulli's principle to remove air and
gases from the condensate Darington feed tank to remove air from the system
to heat the condensate to be used as storage tank for heated feed water dairy
king feed tank form cylindrical tank in three sections first section the lowest
storage space equals beginning of the feed phase middle section atomizing
valve assembly to release entrapped air from the water upper section preheat our
compartment make up thang losses in cycle when the feed water level in the
dairy tank tank drops to a minimum make up feed water enters the system feed
pump pump that forces feed water into the boiler