1. COMPOUNDING OF STEAM TURBINE
To improve the thermal efficiency of any power plant, generally high pressure (near about
120 to 140 bar), high temperature and high-velocity steam is used.
Steam expands from boiler pressure to the condenser in one stage. So, steam's pressure
drop and it will increase its velocity. This high-velocity strikes the turbines rotor and the
speed of the rotor becomes high.
Compounding of steam turbine is used to reduce the rotor speed. It is the process by
which rotor speed come to its desired value. A multiple system of rotors are connected in
series keyed to a common shaft and the steam pressure or velocity is absorbed in stages
as it flows over the blades. Generally, three different types of compounding are used to
reduce the rotor speed of steam turbine.
1. Velocity Compounding
2. Pressure Compounding
3. Pressure Velocity Compounding
3. Advantages
• 1.This arrangement needs small space.
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2. This is very reliable and easy to operate.
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3.Initial cost is low for this arrangement.
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4. Since nozzle's steam is considerable, the turbine does not need to work in high
pressure and turbines structure need not be very strong.
Disadvantages
1.Friction loss is high due to high velocity of steam of nozzle.
2.Its efficiency is low. Because the ratio of blade velocity and steam velocity is not
optimum.
3. First, row is developed maximum power in this system. Later rows are developed
very small power rather than first row.. But fabrication and cost of materials will be
same in all rows.
