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Cross compound steam turbine arrangement
Compounding is the splitting up, into two or more stages, of the steam
pressure or velocity change through a turbine.
Pressure compounding of an impulse turbine is the use of a number
of stages of nozzle and blade to reduce progressively the steam pressure.
This results in lower or more acceptable steam flow speeds and a better
Velocity compounding of an impulse turbine is the use of a single
nozzle with an arrangement of several moving blades on a single disc.
Between the moving blades are fitted guide blades which are connected
to the turbine casing. This arrangement produces a short lightweight
turbine with a poorer efficiency which would be acceptable in, for
example, an astern turbine.
The two arrangements may be combined to give what is called
The reaction turbine as a result of its blade arrangement changes the
steam velocity in both fixed and moving blades with consequent gradual
steam pressure reduction. Its basic arrangement therefore provides
Fig: Cross compound steam turbine arrangement
The term 'cross-compound' is used to describe a steam turbine unit
made up of a high pressure and a low pressure turbine . This
is the usual main propulsion turbine arrangement. The alternative is a
single cylinder unit which would be usual for turbo-generator sets,
although some have been fitted for main propulsion service.
Reheating is a means of improving the thermal efficiency of the
complete turbine plant. Steam, after expansion in the high-pressure
turbine, is returned to the boiler to be reheated to the original superheat
temperature. It is then returned to the turbine and further expanded
through any remaining stages of the high-pressure turbine and then the
Temperature measurement instruments - use of Thermometers, Thermocouple, Radiation pyrometer & Thermistor
- Marine steam turbines operating procedure
The steam turbine has until recently been the first choice for very large
power marine propulsion units. Its advantages of little or no vibration, low
weight, minimal space requirements and low maintenance costs are
considerable. Furthermore a turbine can be provided for any power
rating likely to be required for marine propulsion.
- Impulse steam turbine and reaction steam turbine
The steam turbine is a device for obtaining mechanical work from the
energy stored in steam. There are two main types of turbine, the 'impulse' and the 'reaction'.
The names refer to the type of force which acts on the blades to turn the
- Turbine control and protection
A turbine protection system is provided with all installations to prevent damage resulting from an internal turbine fault or the malfunction of
some associated equipment. Arrangements are made in the system to
shut the turbine down using an emergency stop and solenoid valve.
- Various turbine gearing -Epicyclic gearing,Helical gearing,Flexible coupling &Turning gear
Helical gears have been used for many years
and remain a part of most systems of gearing. Epicyclic gears with their
compact, lightweight, construction are being increasingly used in marine
- Construction of the steam to steam generator - how it works
Steam-to-steam generators produce low-pressure saturated steam for domestic and other services. They are used in conjunction with
watertube boilers to provide a secondary steam circuit which avoids any
possible contamination of the primary-circuit feedwater. .
- Cross compound steam turbine arrangement for marine use
Compounding is the splitting up, into two or more stages, of the steam pressure or velocity change through a turbine. Pressure compounding of an impulse turbine is the use of a number of stages of nozzle and blade to reduce progressively the steam pressure..
Marine machineries - Useful tags
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