Steam Engine

Presented by:

P . Deepak Kumar

Overview of presentation

• History of steam engine

• Classification of steam engine

• Working principle of steam engine

• Components of steam engine

• References/Bibliography

1. History of steam engine

-Thomas Savery (1650-1715)

-Thomas Newcomen 1663-1729

-James Watt (1736-1819)

A steam engine is a heat

engine that performs

mechanical work using

steam as its working fluid.

…history continuedThomas Savery (1650-1715)

Thomas Savery was an English military

engineer. He had been working on solving

the problem of pumping water out of coal

mines. His machine consisted of a closed

vessel filled with water into which steam

under pressure was introduced. This

forced the water upwards and out of the

mine shaft. Then a cold water sprinkler

was used to condense the steam. This

created a vacuum which sucked more

water out of the mine shaft through a

bottom valve.

Thomas Newcomen (1663-1729)

Thomas Newcomen was an English

blacksmith. The Newcomen steam

engine used the force of atmospheric

pressure to do the work. Thomas

Newcomen's engine pumped steam

into a cylinder. The steam was then

condensed by cold water which

created a vacuum on the inside of the

cylinder. The resulting atmospheric

pressure operated a piston, creating

downward strokes.

http://en.wikipedia.org/wiki/File:Newcomen_atmospheric_engine_animation.gif

James Watt (1736-1819)

James Watt was a Scottish inventor and

mechanical engineer, born in Greenock, who was

renowned for his improvements of the steam

engine. In 1765, James Watt while working for

the University of Glasgow was assigned the task

of repairing a Newcomen engine, which was

deemed inefficient but the best steam engine of

its time. Most notable was Watt's 1769 patent for

a separate condenser connected to a cylinder by a

valve. Unlike Newcomen's engine, Watt's design

had a condenser that could be cool while the

cylinder was hot.

Modern Steam Engine is based on

the principle of Rankine Cycle

Classification of Steam Engines

1. Based on axis of engine:

Orientation of cylinder axis

I. Horizontal steam engine

II. Vertical steam engine

2. Based on speed of engine:

I. High speed engine- speed of 250rpm and above

II. Medium speed engine- speed 100 to 250 rpm

III. Slow speed engine- speed 100rpm and below

3. Based on type of steam action:

I. Double acting steam engine

II. Single acting steam engine

Horizontal Steam Engine

Double Action Steam Engine

Single Action Steam Engine

4. Based on expansive or non expansive type of working:

I. Steam is injected throughout the piston stroke

II. Steam is injected partially piston stroke and partially expansion

5. Based on type of exhaust from engine:

I. Condensing engine

II. Non-condensing engine

6. Based on number of stages:

Number of stages of expansion in steam engine

I. Single stage

II. Two stage

III. Three stage

IV. Four stage

7. Based on number of cylinders:

I. Simple steam engine: one cylinder

II. Compound steam engine: more than one

cylinder

8. Based on type of governing:

I. Throttle governed engine

II. Cut-off governed engine

9. Based on type of application:

I. Stationary engine

II. Marine engine

III. Locomotive engine

Marine Steam Engine

Compound Steam Engine

Working of Steam Engine

Steam from the boiler

enters the steam chest

and is admitted to the

front end of the cylinder

by the valve slide.

The high pressure steam

presses the piston

backward, driving

the engine wheels

around one half turn

At the end of the piston

stroke the valve shifts,

allowing the expended

steam to escape through

the exhaust port.

Sliding valve

At the end of the

forward stroke, the

steam is released

from the rear portion

of the cylinder

At the same time, the

valve slide begins

admitting high pressure

steam to the back end

of the cylinder.

This presses the piston

forward, pulling the

engine wheels around

another half turn.

Working of Steam Engine

Components of Steam Engine

1. Piston and Piston rod

2. Piston rings

3. Connecting rod

4. Crank and crank shaft

5. Stuffing box

6. Crosshead and guide

ways

8. Eccentric

9. Slide valve

Piston and Piston Rod

• A piston is made of cast iron and acts as a sliding

round plug inside of the cylinder. It is secured to

the piston rod by a nut.

• The piston rod is round, made of steel, the top end

is secured to the piston, the bottom end to the

crosshead. To prevent steam from blowing out of

the cylinder around the rod, metallic type packing

is installed around the rod in the stuffing box.

Piston Rings

• To prevent the steam from flowing through the

clearance between the piston and cylinder walls

piston rings are installed.

• They are constructed of fine grade cast iron and

have a sliding fit in a groove around the outside of

the piston. The plain snap type piston ring is made

oversize and is held out tight against the cylinder

wall by the tension in the ring, set up by its having

to be compressed when installed.

Connecting Rod

• The connecting rod is made of steel.

• It connects piston with the crosshead with

bearings so that the crankpin is free to turn as the

crank moves.

Crank and Crank Shaft

• The crank is made of steel and consists of the

following parts.

– Webs which are the two side pieces connecting

the crankshaft with the crankpin.

– Crankpin which is a round steel pin between

the outer ends of the crank webs, around which

the crankpin bearing is fitted.

• The crankshaft is a large round steel shaft to

which the cranks are attached.

Stuffing Box

• Stuffing box is a kind of packing box through

which the reciprocating shaft/rod passes and

leakage across the reciprocating member is

prevented.

Crosshead and Guide ways

• A crosshead is a square steel block rigidly fastened

to the bottom end of the piston rod. On the

forward and after side of the block is a round steel

pin known as the crosshead pin, around which the

crosshead bearings fit.

• The guide is a flat face made of cast iron and

bolted against the column. The astern guide

consists of two cast iron side bars which fit around

the outside of the slipper preventing it from being

pulled away from the guide when the engine is

turning in the astern motion.

Eccentric

• The eccentrics which move the engine valves up

and down are merely an off center or eccentric

wheel secured around and keyed to the outside of

the crankshaft.

• The motion of the moving eccentric is transmitted

to the eccentric rod by the eccentric strap which

extends entirely around the outside of the

eccentric, the eccentric turning inside of it.

Slide Valve

• Slide valve is used in steam engine for quantitative regulation of supply of live steam into cylinder and exhaust of dead steam from cylinder.

• Slide valve is operated by the valve rod connected to eccentric rod and eccentric.

• It is of two type:

1. D-slide valve

2. Piston valve

References/ Bibliography

1. Animated engines-Illustrates a variety of engines

2. Howstuffworks- “How Steam Engines Work”

3. http://en.wikipedia.org/wiki/Steam_engine

4. http://en.wikipedia.org/wiki/Steam_engine_history

Thanks for your

kind attention