TURBINE and ENGINE GOVERNORS.pptx

7/29/2019 TURBINE and ENGINE GOVERNORS.pptx

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Power Plant Engineering (ME 3125)

k.j.k krishantha anurudha

10/273

Mechanical(Production)

TURBINE and ENGINE

GOVERNORS


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TURBINES

A turbine is defined as a device which draws energy from a fluid moving at a high speed

and converts that energy into work. The purpose of turbines is basically to produceelectricity and to propel various machinery and objects via the mechanical energyproduced.

Every turbine has a one basic principle that is: a moving fluid which can be water, steam,wind or gas is made to run over blades at a high speed, the blades induced by the moving

fluid start rotating and as a result they start the rotor engine attached to the device whichis responsible for converting the energy into work.

The first turbines to be used were the steam turbines but now on the basis of the fluidfrom which energy is extracted there are four major types of turbines:

Steam turbines Water turbines

Wind turbines

Gas turbines


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STEAM TURBINE

The steam which is produced by the burning of coal, oil or from nuclear reactor

is made to pass through blades which spin at a very high speed to drive the

generator which produces energy.

The principle on which it works is that the thermal energy which is extracted

from the steam is converted into mechanical energy.


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Blade material must have some or all of the following properties, depending on the

position and role.

Corrosion resistance (especially in the wet LP stage)

Tensile strength (to resist centrifugal and bending stresses)

Ductility (to accommodate stress peaks and stress concentrations)

Impact strength (to resist water slugs)

Material damping (to reduce vibration stresses)

creep resistance

12% Cr stainless steels are a widely used material


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WATER TURBINE

Water turbines work on the same principle as the steam turbines but thedifference is that they use water instead of steam. The water used by these

turbines comes from lakes and rivers.

Dams which are built in these huge water bodies store the water at one end, at

the other end they possess hydraulic turbines which possess a shaft bearingvertical blades and a generator which produces hydroelectric power which is in

turn used as electricity.


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Water droplets in the last stages of a turbine can cause erosion at the leading

edge of moving blades, and cracks can form. Leading edges can be protected

by surface hardening or by welding a shield of hard material such as tungsten

chromium tool steel or satellite (an alloy of cobalt and chromium). Shields

will probably need to be replaced once during the lifetime of the turbine.

Rotor of a water turbine


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WIND TURBINES Wind turbines use up the moving wind to produce electricity.

These turbines might not be as popular as water and steam turbines but in manyparts of the world like in Scotland and some parts of America this turbine is used toproduce electricity.

Long egg beater- like shafts, possessing bow shaped blades, are placed high inthe sky. These blades move with the moving wind to produce electricity.

Producing electricity from wind may sound a good option as wind is a resourcewhich can never end; however this process has huge restrictions as wind is asreliable as water.

It can only be applicable in parts of the world where wind moves fast continuously.


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WIND BLADE COMPOSITION

*Wood

Strong, light weight, cheap, abundant, flexible

Popular on do-it yourself turbines

*Metal

Steel

Heavy & expensive

Aluminum

Lighter-weight and easy to work with

Expensive

Subject to metal fatigue

*Blade Construction FiberglassLightweight, strong, inexpensive, good fatigue characteristics

Variety of manufacturing processes can be used

Most modern large turbines use fiberglass


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GAS TURBI NE

Gas turbines use up high pressure gas to produce energy.

These turbines are not used for producing electricity but they are used to propel

jet engines.

Gas turbines are the latest types of turbines. Their structure is advanced but the

principle is same.


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Applications:

Jet Engines

Gas Turbine Generators

Materials should be:

Very high temperatures

Strength / Fatigue Life

Machinability Material used:

Initially Steel

Nickel Alloys

Most common material is Titanium

Laser peening

Ceramic Coatings


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GOVERNORS

Generally governors are used to maintain a fixed speed not readily adjustable

by the operator or to maintain a speed selected by means of a throttle control

lever. In either case, the governor protects against over speeding.

Governors serve three basic purposes:

Maintain a speed selected by the operator which is within the range

of the governor.

Prevent over-speed which may cause engine damage.

Limit both high and low speeds.


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HOW DOES IT WORK?

If the load is removed on an operating engine, the governor immediately

closes the throttle. If the engine load is increased, the throttle will be opened to prevent

engine speed form being reduced.

Function

To maintain the engine speed at the desire value by controlling the fuelinjection.

Mainly there are three types of governor. They are,

Centrifugal Governor

Pneumatic Governors

Electronic Governor


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Mainly used for power generation and their function remains the same in this

situation as well. The power delivered by the alternator needs to be constant

despite load variations and this depends to a great degree on the speed at

which the prime mover of the generator diesel engine is rotating since the

alternator is getting its movement from that engine only. Hence the role ofthe governor is equally important in this case as well.


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THANK YOU !!!!!Presented by

K.J.K. Krishantha Anurudha

(10/273)

Mechanical (Production)

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TURBINE and ENGINE GOVERNORS.pptx