Compounding.pptx

Compounding in Steam Turbine

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

2. 1. Velocity Compounding :- This method is used in  CURTIS TURBINE .

3. Advantages 1.This arrangement needs small space. 2. This is very reliable and easy to operate. 3.Initial cost is low for this arrangement. 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.

4. 2. Pressure Compounding:- This method is used in  RETEAU and ZOELLY TURBINE .

5. 3. Pressure-velocity Compounding:- A  CURTIS TURBINE  is an example of pressure velocity compounded method.