a steam turbine cogeneration installation, large gas boilers heat water to produce
high-pressure steam. Steam boilers produce steam with temperatures up to 950 degrees
under as much as 1300 pounds of pressure. Natural gas usually fuels the boilers,
but fuel oil can also be used when necessary, providing uninterrupted service
when natural gas is in short supply.
steam from the boilers turns the turbines at a speed of 3600 rpm. The rotating
turbines drive the AC (Alternating Current) generators to produce electrical power.
Steam turbines are classified into two general groups: Impulse Turbines
and Reaction Turbines, depending on the method used
to cause the steam to be useful.
be further classified according to the following:
- Type and arrangement
of steam flow
of steam flow
- Division of
turbine may also be classified by whether it is a condensing unit (exhausts to
a condenser at a pressure below atmospheric pressure) or a non-condensing unit
(exhausts to another system such as the auxiliary exhaust steam system at a pressure
above atmospheric pressure).
the operating and controlling equipment, similarity exists in both the impulse
and reaction turbines. These include foundations, casings, nozzles, rotors, bearings,
and shaft glands.
function of the nozzles is to convert the thermal energy of steam into kinetic
energy. The secondary function of the nozzles is to direct the steam against the
rotors (forged wheels and shaft) are manufactured from steel alloys. The primary
purpose of a turbine rotor is to carry the moving blades that convert the steam's
kinetic energy to rotating mechanical energy.