Introduction to Steam turbine | Parts Of Steam turbine and its Function

Introduction to Steam turbine | Parts Of Steam turbine and its Function

Introduction to Steam Turbines

A steam turbine is a device that converts the thermal energy of steam into mechanical energy by turning the blades of a rotor.

• Steam turbine convert a part of the energy of the steam evidenced by high temperature and pressure into mechanical power-in turn electrical power
• The steam from the boiler is expanded in a nozzle, resulting in the emission of a high velocity jet. This jet of steam impinges on the moving vanes or blades, mounted on a shaft. Here it undergoes a change of direction of motion which gives rise to a change in momentum and therefore a force.
• The motive power in a steam turbine is obtained by the rate of change in momentum of a high velocity jet of steam impinging on a curved blade which is free to rotate.
• The conversion of energy in the blades takes place by impulse, reaction or impulse reaction principle.
• Steam turbines are available in a few kW(as prime mover) to 1500 MW

As prime movers in all thermal and nuclear power plants to produce electricity, large ships, pumps and fans at petrochemical plants.

Parts of Steam Engine and Its Functions.

Steam engines are used very widely in engineering up to 1930 for generation of power but after it are replaced by internal combustion engine. Diesel engine, petrol engine are the common example of internal combustion engine. Steam engines are widely used on ships in old days at present they are replaced by diesel engines. To disclose some more important information about this old machine, I am giving some details about its parts and their functions in operating.

01) Frame: –
It is the heavy casting which supports all the stationary and moving parts of the engine and holds them in proper alignment. It requires foundation to rest upon or engine bed plate fixed on engine foundation.

02) Cylinder: –
It is the cast iron cylindrical hollow vessel in which the piston moves to and fro under the pressure of steam. Crank side end and outer end of cylinder is closed by end covers and made steam-tight.

03) Steam Chest: –
It is the closed chamber integral with the cylinder. It supplies steam to the cylinder with the movement of slide valve.

04) Stuffing Box and Gland: –
This part is fitted on the crank end cover of the cylinder and their function is to prevent the leakage of steam past the piston rod.

05) Piston: –
It is the cast iron cylindrical disc moving to and fro in the cylinder under the action of the steam pressure. This part converts heat energy of steam into mechanical work. Cast iron piston rings make the piston steam tight in the cylinder and thereby prevent the leakage of steam past the piston.

06) Cross head: –
It is the link between piston rod and the connecting rod. It guides the motion of the piston rod and prevents it from bending.

07) Connecting Rod: –
It is cast iron part which helps to convert reciprocating motion of piston into rotary motion of the crank. Gudgeon pin is used to connect one end of connecting rod to cross head and its open end is connected to the crankshaft.

08) Crankshaft: –
It is made from mild steel on which flywheel is mounted on it. It is supported on the main bearings of the engine and it is free to rotate in them.

09) Slide Valve: –
Fixed on the steam chest and its function are to admit the steam from steam chest to the cylinder, and exhaust the steam from the cylinder at the proper moment. The valve gets to and fro motion from the eccentric fitted on the crankshaft.

10) Main Bearings: –
This part support crank shaft and fitted in the engine frame known as main bearing journal.

11) Flywheel: –
It is made from cast iron or cast steel and mounted on the crankshaft to prevent the fluctuation of engine speed throughout the stroke and to carry the crank smoothly over the dead centers.

12) Governor: –
To control the speed of the engine according to the load conditions, the governor is used. The speed of the engine is controls either by the quantity or pressure of the steam supplied to the engine.