growth of the steam-engine
DESCRIPTION
Growth of the STEAM-ENGINE.pptTRANSCRIPT
Department of Mechanical Engineering, UET Peshawar
Steam Engine
Presentation by: Muhammad Fahad
Khan Abdul Rizwan Rahat Saeed Fahim Ullah Fazal Haq
Contents
Introduction to Steam EngineTypes of Steam EngineParts of Steam EngineWorking of Steam EngineAdvantages, Disadvantages & Uses of Steam Engine
Outlines Introduction to steam engine Growth of the steam engine
Opening Temple-Doors by Steam Brancas Steam-Engine, A.D. 1629
The Steam Engine as a train mechanism Newcomen's Engine, A. D. 1705
The development of modern steam engine JAMES WATT
The Modern Steam Engine and application to locomotives
Introduction to Steam Engine
Introduction
Steam engine is an external combustion heat engine in which steam is used as a working fluid.
Heat engine works on first law of thermodynamics i.e heat energy is converted to mechanical work.
It is among the ancient Egyptian civilization that we find the first records in the early history of the steam-engine.
Growth of the Steam Engine Opening Temple-Doors
by Steam
HERO, a learned writer in ancient Egyptian civilization
Spherical vessel containing water
A pipe connects the upper part of this sphere with the hollow and air-tight shell.
Fire on the altar, the heated air expands
On extinguishing the fire, the air condenses, the water returns from the bucket to the sphere
Growth of the Steam Engine conti..
Brancas Steam-Engine. A.D. 1629
Metal vessel partly filled with water
Pipe fitted, leading nearly to the bottom, and open at the top
Fire being applied, the steam formed by drove the water out through the vertical pipe
The Steam Engine as a train mechanism
Newcomen's Engine, A. D. 1705
A jet of water was thrown directly into the cylinder, thus effecting for the Newcomen engine
A jet of water from the reservoir, g, enters the cylinder, producing a vacuum by the condensation of the steam
The Development Of Modern Steam Engine “JAMES WATT”
Watt's Experiment
14‑inch diameter and 10 inches long brass surgeon's syringe.
At each end was a pipe leading steam from the boiler, and fitted with a cock to act as a steam valve.
A pipe led also from the top of the cylinder to the condenser.
The Modern Steam Engine
Leopold's Engine, 1720
Two single‑acting cylinders
Receives steam alternately from the same steam‑pipe through a " four‑way cock," and exhausts into the atmosphere.
The alternate action of the steam pistons is secured by turning the four‑way cock into the reverse position
Steam Engine To Locomotives
Newton's Steam‑Carriage,1680
Spherical boiler mounted on a carriage.
Reaction on the carriage, drives the latter ahead.
The driver controls the steam by the handle and cock.
Steam Engine To Locomotives
Read's Steam Carriage, 1790
A A A A are the wheels; B B, pinions on the hubs of the rear wheels .
CO is the boiler.
Cocks, serve to shut off steam from the engine .
Objectives:
Reciprocatory Engines
Single Stage Reciprocatory
Engines
Compound Engines
Turbine Engines
Stationary Engines
Types Of Steam Engine
Classification
Steam engines can be classified in two main ways:
By the technology used
By the application
By The Technology:
Most steam engines use either
Piston Engines
Turbines
By The Application:
By application the steam engines are classified further into two main groups:
Engines providing power, which stop rarely and do not need to reverse i.e. power stations
Engines that frequently stop and reverse i.e. stationary engines
Reciprocatory Engine:
These engines are further divided into two categories:
Single stage Reciprocatory Engines
Compound or multi stage Reciprocatory Engines
Single Stage Reciprocatory Engine:
A reciprocating engine, also often known as a piston engine, is an engine that utilizes one or more pistons in order to convert pressure into a rotating motion.
In single stage all the cylinders must produce same pressure.
Single Stage Reciprocatory Engine:
Working:
Each piston is located inside a cylinder, into which a fuel and air mixture is introduced, and then ignited.
The now hot gases expand, pushing the piston away. The linear movement of the piston is converted to a circular movement via a connecting rod and a crankshaft.
The more cylinders a piston engine has, the more power it is capable of producing.
Compound Engine:
A compound engine unit is a type of steam engine where steam is expanded in two or more phases.
Steam is first expanded in a high-pressure (HP) cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger volume low-pressure (LP) cylinders.
An animation of a double-acting inverted triple-expansion marine engine
inlet
exhaust
Stage one Stage two
Stage three
High pressure stage
Low pressure stage
Compound Engine With Two Pistons
Working
The complete expansion of the steam occurs across multiple cylinders and, as less expansion now occurs in each cylinder, less heat is lost by the steam in each. This reduces the magnitude of cylinder heating and cooling, increasing the efficiency of the engine.
Working of reciprocatory engine
Turbine or Rotary Engines:
A turbine is a rotary engine that extracts energy from a fluid flow.
Moving fluid acts on the blades to spin them and impart energy to the rotor. Early turbine examples are windmills and water wheels.
A turbine operating in reverse is called a compressor or Turbo pump.
Steam Turbine:
Turbine Blades
Stationary Engines
A stationary engine is an engine that does not move. Usually, a stationary engine is used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tools.
Stationary engines come in a wide variety of sizes and use a wide variety of technologies.
Examples
Small stationary engines were frequently used on a farm to drive various kinds of power tools and equipment such as circular saws, pumps, and hay elevators.
Power stations of all sizes.
Beam engines used in mills and factories before the widespread use of electric power.
Dry Power Station
Power Station
Parts Of A Steam Engine
• Crank Shaft• Eccentric• Eccentric Rod• Valve Rod• Fly Wheel• Governor• Cross Head• Connecting
Rod
• Frame• Cylinder• Steam Chest• D-Sliding Valve• Inlet & Exit Port• Piston• Piston Rod
Following are the main parts of the Steam Engine:
Frame
Frame
Supports the stationary and moving parts.
Hold the parts in proper position.
Rests on engine foundation.
Cylinder
Cylinder
Cylinder
Cylindrical hollow vessel in which the piston moves to & fro under the pressure of steam.
Steam Chest
Steam Chest
Acts as reservoir of steam for cylinder.
Contains valve system.
D-Sliding Valve
D-Sliding Valve
Moves with simple harmonic motion with in steam chest.
Connected to eccentric.
Provides inlet and exhaust of steam at proper timing.
Piston
Piston
Cylindrical disc, which moves to & fro inside the cylinder under the pressure of steam.
Converts the heat energy of steam ino mechanical work.
Piston Rod
Piston Rod
Circular rod connects the piston with the cross head.
Cross Head
Cross Head
Cross Head
Link Between Piston rod & connecting rod.
Provides guidance to the motion of piston rod.
Connecting Rod
Connecting Rod
One end connected to the connecting rod & other to the crank shaft.
Converts the reciprocating motion of the piston into the rotary motion of the crank shaft.
Eccentric
Eccentric
Eccentric
Fitted to crank shaft.
Provides the reciprocating motion to the slide valve.
Fly Wheel
Fly Wheel
Heavy Cast Iron Wheel mounted on crank shaft.
Prevents the fluctuations of the engine by storing mechanical energy.
Governor
Governor
Keeps the speed of the engine uniform at different load conditions by controlling the amount of steam supplied to the engine.
Governor
The Working of Steam Engine is based on the Rankine Cycle.
Working Of Steam Engine
RANKINE CYCLE
•The Rankine cycle is a thermodynamic cycle which converts heat into work. •Water is used as the working fluid in this cycle.•80% of all electric power used throughout the world is produced using this cycle.•It is named after William Rankine, a Scottish polymath.•It is referred to as a practical Carnot cycle.•A Rankine cycle describes a model of steam operated heat engine.
RANKINE CYCLE(CONTINUED)
The main difference is that heat addition and rejection are isobaric in the Rankine cycle and isothermal in the theoretical Carnot cycle.
A pump is used to pressurize liquid instead of gas. This requires a very small fraction of the energy compared to compressing a gas in a compressor (as in the Carnot cycle).
The efficiency of a Rankine cycle is usually limited by the working fluid.
One of the principal advantages the Rankine cycle holds over others is that during the compression stage relatively little work is required to drive the pump.
Processes of the Rankine cycle
PROCESSES(CONTINUED)
Process 4-1: The working fluid is pumped from low to high pressure, as the fluid is a liquid at this stage the pump requires little input energy.
Process 1-2: The high pressure liquid enters a boiler where it is heated at constant pressure by an external heat source to become a dry saturated vapor.
Process 2-3: The dry saturated vapor expands through a steam engine, generating power. This decreases the temperature and pressure of the vapor, and some condensation may occur.
Process 3-4: The wet vapor then enters a condenser where it is condensed at a constant pressure to become a saturated liquid.
THERMAL EFFICIENCY OF RANKINE CYCLE
Heat Supplied during Process,1-2=QS=h2-h1
Heat Rejected during Process,3-4=QR=h4-h3
Work Input=h4-h1
Useful Work Output=h2-h3
Net Work= (h2-h3) + (h4-h1) Thermal Efficiency= η= Net Work/ QS
= (h2-h3) + (h4-h1)
(h2-h1)
WORKING OF STEAM ENGINE
WORKING(CONTINUED) Steam is generated, under pressure, in a boiler. From the
boiler the steam enters the cylinder at the front of the piston, through the port A. This is called the inlet or steam port.
The pressure of the steam pushes the piston, along the cylinder, in the direction of arrow C.
The steam at the back of the piston, (from the previous stroke), is pushed out through port B. This is called the exhaust port.
As the piston, moves along the cylinder so does the piston rod, which is fixed to the crosshead. The crosshead keeps the piston, and piston rod, moving horizontally.
Also fastened to to the crosshead is one end of the connecting rod. The other end is fastened to the crank.
As the piston and piston rod move backwards and forwards, the connecting rod causes the crank, crankshaft and flywheel to rotate in the direction shown.
VALVE MECHANISM
The admission of steam into the cylinder has to be controlled so that live steam (steam from the boiler) pushes the piston backwards and forwards to obtain a continuous rotary motion to the crank. The mechanism that controls the steam admission is called the valve gear or valve mechanism.
ECCENTRIC
The valve is moved backwards and forwards over the cylinder ports by the action of the eccentric. The eccentric consists of a circular disc, which is fastened to the crankshaft and rotates with it. The centre of crankshaft is made offset (eccentric) to the centre of the disc. Thus, when the crankshaft rotates, a point on the centre of the eccentric disc forms a circle around the crankshaft centre. The diameter of this circle will be twice the offset.
If the slide valve is connected to the eccentric by means of an eccentric rod, then as the crankshaft rotates, the valve will move backwards and forwards by a distance which is twice the offset of the centers. This distance is known as the throw of the eccentric.
ECCENTRIC(CONTINUED)
SLIDE VALVE OPERATION
VALVE OPERATION (CONTINUED)
VALVE OPERATION (CONTINUED)
VALVE OPERATION (CONTINUED)
It is used for driving machinery in factories and mills. Steam-powered transport on both sea and land. Very low power engines are used to power models and speciality application such as
the steam clock. power supplied to the electric grid is predominantly generated
using steam turbine plant. Transport applications
engines have been used to power a wide array of transport appliances:
* Marine: Steamboat, Steamship* Rail: Steam locomotive, Fireless locomotive* Agriculture: Traction engine, Steam tractor* Road: Steam wagon, Steam bus, Steam tricycle, Steam car* Construction: Steam roller, Steam shovel* Military: Steam tank (tracked), Steam tank (wheeled)* Space: Steam rocket
It convert heat from almost any source to mechanical work. Steam engines are no adversely effect by atmospheric pressure . For road vehicles steam propulsion has the advantage of having high torque
from stationary, removing the need for a clutch and transmission. Also a steam train with similar speed and capacity is 50 percent lighter than an
electric or diesel train. Thus, especially rack railways, significantly reducing wear and tear on the track.
improvements like roller bearings, heat insulation, light-oil firing, improved inner streamlining, one-man-driving and so on. These resulted in 60 percent lower fuel consumption per passenger and massively reduced costs for maintenance and handling.
They are noisy and require a lot of fuel. Low efficiency, which means you have to put
more energy in (as compared to other modes)
than you get out. The disadvantages of using a steam train is the efficiency, it is low. Typical steam
engine efficiency cannot reach more than 30%. The other problem is obviously it needs plenty of fossil fuel in order to create
steam for the engine. Fossil fuel will be gone soon if people do not look for alternative.
Its parts were large and difficult to keep in proper alignment. Great power loss through friction because parts are being cast and not properly
machined.