Steam Engine Defination | Types and Principle Of Steam Engine
WHAT IS THE DEFINATION OF STEAM ENGINE?
Steam engine is a device which converts heat energy into mechanical energy and heat is supplied into the engine through the medium of steam.This is a mechine where steam is used as a working substance.Steam engine works on the principle of first law of thermodynamics where work and heat are mutually convertible.This is a very basic defination of steam engine.
In a steam engine there is a cylinder fitted with a piston. Then steam from the boiler enters to the engine cylinder and the cylinder is made act on the piston which thereby reciprocates to and fro motion of the piston. So heat energy in the steam is converted into mechanical work, thus, it is called Reciprocating steam engine.
First steam engine was invented in 1712 by Thomas Newcomen and his assistant John Calley.
HOW TO MAKE A STEAM ENGINE?
In a steam engine, high-pressure superheated steam from boiler is fed into the steam chest. Here a D-shaped valve V,called D-slide valve, moves to and fro in a steam chest and this valve regulates the supply of steam into the engine cylinder is operated by a mechanism E, called eccentric which is situated on the crankshaft. There are two different ports A and B in which steam is led into the cylinder on the two sides of the piston and K is the exhaust port in which steam is led out of the cylinder.
When D slide valve moves to the right, steam from steam chest enters from the left side through port A. This high-pressure steam pushes the piston to the right side of the crank end. This is called the forward stroke of the piston. With the movement of piston, crosshead moves to the right thus pushing the connecting rod which also pushes the crank to the right side. Now the crank and crankshaft both rotate in clockwise direction,show in the picture.
When piston is in extremely right side or nearer to crank end cover, the V valve is moving towards the left direction and open the steam port B in which steam is entering into the cylinder through this port. So, the piston is now moving left side direction or away from the crank.This is called the returned stroke of the piston.The piston is starting to move in left direction and left side steam leaves the cylinder through the exhaust port K via port A.
Again when the piston is in the extreme left condition, the valve V are starting to move the right direction and open the port A.As a result, steam enters the cylinder through port A and piston starts to move at right direction. Now the right side cylinder's steam leaves the cylinder through the exhaust port K via port B.
In this way, the piston is moving to and fro motion in the cylinder's chamber and it circulates crankshaft through piston rod, connecting rod and crank. This process is continuously running and as such the steam engine works. At the end of the each stroke, the piston changes its direction of motion and it is momentarily stopped.this is called dead centres of the crank.The above steam engine is called single cylinder double acting horizontal reciprocating steam engine.
TYPES OF STEAM ENGINE
Steam Engines are different categories.Here we will disscuss some important categories:
1. According to the position of cylinder:-
a. Horizontal Steam Engine: When axis is horizontal position in steam engine,it is called horizontal steam engine.
b. Vertical Steam Engine: When axis is vertical position in steam engine,it is called vertical steam engine.
2. According to the number of working stroke:-
a. Single Acting Steam Engine: When steam is coming in one side of the piston and it produces one single working stroke in each revelution of the crankshaft,is called single acting steam engine.
b. Double Acting Steam Engine: When steam is coming in both side of the piston and it produces double working stroke in each revelution,is called double acting steam engine.It produces double power than single acting steam engine.
3. According to the number of cylinders in which steam expands:-
a. Simple Steam Engine: When expansion of steam is carried out in a single cylinder,called simple steam engine.
b. Compound Steam Engine: When expansion of steam is carried out in a two or more cylinders,called compound steam engine.
4. According to the type of exhaust:-
a. Condensing Steam Engine: When steam is exhausted in a condenser called condensing steam engine.
b. Non-Condensing Steam Engine: When steam is exhausted in the atmosphere called non-condensing steam engine.
5. According to the method of governing:-
a. Throttling Steam Engine: When steam engine speed is controlled by throttle valve in the steam pipe which regulates the pressure of steam to the engine.
b. Automatic cut-off Steam Engine: When steam engine speed is controlled by an automatic cut-off governor which controls the steam pressure to the engine.
6. According to the speed of crankshaft:-
a. Slow Speed Steam Engine: When the speed of the crankshaft is below 100 revolution per munite,called slow speed steam engine.
b. Medium Speed Steam Engine: When the speed of the crankshaft is in between 100-250 revolution per munite,called medium speed steam engine.
c. High Speed Steam Engine: When the speed of the crankshaft is above 250 revolution per munite,called high speed steam engine.
7. According to the field of application:-
a. Stationary Engine
b. Locomotive Engine
c. Marine Engine
8. According to the valve gear used:-
a. Slide Valve Engine
b. Corlis Valve Engine