STUDY OF STEAM TURBINE ROTOR PROJECT REPORT

INTRODUCTION
Generation of power in abundance is needed for any country to develop into an industrial nation. It is possible to generate power using thermal, tidal or nuclear energy. Thermal power plants play a key role in the generation of power in view of the abundant coal supplies in our country. Steam turbine, mechanical rotating equipment which consists of stationary and moving blade rows, is the main component of a thermal power plant. A steam turbine based power plant involves raising high-pressure steam in a boiler from the thermal energy and expanding the steam in a turbine to generate shaft power, which in turn is converted into electricity in a generator. In the power generation industry gas turbines and steam turbines are widely used for generating power. These industrial machines are capable of producing power in hundreds of megawatts. Industrial applications need mechanical energy to drive the generator..

Steam Turbines

Introduction to the Steam Turbine
De Laval, Parsons and Curtis developed the concept for the steam turbine in the 1880's.Steam turbines are used in all of our major coal-fired power stations to drive the generators or alternators, which produce electricity. The turbines themselves are driven by steam generated in 'Boilers' or 'Steam Generators' as they are sometimes called.

PARTS OF A TURBINE

1. Main oiling pump.

2. Journal Bearing.

3. Outer Casing.

4. Inner Casing.

5. Combined thrust and Journal bearing.

6. Turbine Rotor.

7. Turbine Rotor.

8. Cross cover piping.

9. Outer casing.

10.Exhaust hood.

11.HP Guide Blade Carrier.

12.LP Guide Blade Carrier.

13.Diffuser.

14.Bellows.

15.Journal Bearing.

16.Balance Piston Gland.

Working principle of Steam Turbine
A steam turbine is a prime mover, which converts the energy stored in the steam into rotational mechanical energy. In general, nozzle and blade are the two most important elements of a steam turbine. As the steam passes through the nozzle, the steam pressure falls and due to this fall in the pressure certain amount of heat energy is converted into kinetic energy i.e. steam is given a high velocity. The rotor blades (moving part of the turbine) change the direction of motion of this high velocity steam and thus give rise to change in momentum and therefore a force. The force acts on the blades and thus rotates the shaft on which the blades are mounted. Thus the energy stored in the steam is converted into rotational mechanical energy and then this energy is used to drive the generators coupled to the shaft. The turbine shaft is connected to a generator, which produces the electrical energy. The rotational speed is 3,000 rpm for Australian (50 hertz (Hz)) systems and 3,600 for American (60 Hz) systems.

The Turbine is a rotary device that affects an exchange of energy between a flowing fluid and a rotating shaft. In a steam turbine, the energy transfer takes place in two
steps:

1. The available energy in the hot and high pressure steam is first converted into kinetic energy by the expansion of steam in a suitably shaped passage known as nozzle from which it issues as a high velocity jet having a high tangential component.

2. Then a part of this kinetic energy and sometimes part of the pressure energy are converted into mechanical energy by directing the jet at a proper angle, against curved blades mounted on a rotating disc. The rotor compiled to generator produces the electricity.

A turbo machine consists of a rotating part having a series of vanes or buckets arranged around its periphery and a set of stationary vanes used to control the angular momentum of the fluid passing through it. The pressure falls in the flow through a turbine stage and a high loading may not lead to excessive boundary layer growth or separation. The same level of energy exchange in a turbine can be affected with fewer stages.

Many of the utility steam turbines are of three cylinder construction i.e. High pressure cylinder in which pressure is maximum with minimum specific volume so that blade height is minimum, Intermediate pressure cylinder in which pressure is intermediate so that the blade height is intermediate and subsequently low pressure cylinder which has a minimum pressure level and maximum specific volume hence maximum blade height is maximum.

After the steam has passed through the HP stage, it is returned to the boiler to be re-heated to its original temperature although the pressure remains greatly reduced. The reheated steam then passes through the IP stage and finally to the LP stage of the turbine. Of all heat engines and prime movers the steam turbine is nearest to the ideal and it is widely used in power plants and in all industries where power and/or heat are needed for processes. These include: pulp mills, refineries, petro-chemical plants, food processing plants, desalination plants, refuse incinerating and district heating plants.