Steam Turbine Essay

Operating Principles
A steam turbine's two main parts are the cylinder and the rotor. As the steam passes through the fixed blades or nozzles it expands and its velocity increases. The high-velocity jet of steam strikes the first set of moving blades. The kinetic energy of the steam changes into mechanical energy, causing the shaft to rotate. The steam then enters the next set of fixed blades and strikes the next row of moving blades. As the steam flows through the turbine, its pressure and temperature decreases, while its volume increases. The decrease in pressure and temperature occurs as the steam transmits energy to the shaft and performs work. After passing through the last turbine stage, the steam exhausts into the condenser or process steam system. The kinetic energy of the steam changes into mechanical erringly through the impact (impulse) or reaction of the steam against the blades.

TURBINE CLASSIFICATION:

1. Impulse Turbine:- In Impulse Turbine steam expands in fixed nozzles. The high velocity steam from nozzles does work on moving blades which causes the shaft to rotate. The essential features of impulse turbine are that all pressure drops occur at nozzles and not on blades. A simple impulse turbine is not very efficient because it does not fully use the velocity of

turbine via interceptor valves and control valves and after expanding enters the L.P. turbine stage via 2 numbers of cross over pipes. In the L.P. stage the steam expands in axially opposite direction to counteract the trust and enters the condenser placed directly below the L.P. turbine. The cooling water flowing throughout the condenser tubes condenses the steam and the condensate collected in the hot well of the condenser. The condensate collected is pumped by means of 3*50% duty condensate pumps through L.P. heaters to deaerator from where the boiler feed pump delivers the water to boiler through H.P. heaters thus forming a closed