Balances Speed Controller

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BALANCES SPEED CONTROLLER


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As the steam flows through the nozzle itspressure falls from inlet pressure to the exit

pressure (atmospheric pressure, or more usually,the condenser vacuum).

Due to this higher ratio of expansion of steam inthe nozzle the steam leaves the nozzle with a

very high velocity. The steam leaving the moving blades has a large

portion of the maximum velocity of the steamwhen leaving the nozzle.

The loss of energy due to this higher exit velocityis commonly called the carry over velocityorleaving loss.


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Reaction turbines working

principle In the reaction turbine, the rotor blades

themselves are arranged to form convergentnozzles.

This type of turbine makes use of the reactionforce produced as the steam acceleratesthrough the nozzles formed by the rotor.

Steam is directed onto the rotor by the fixedvanes of the stator.

It leaves the stator as a jet that fills the entirecircumference of the rotor.


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Impulse VS Reaction Turbine

Impulse turbine

All available energy of the fluid isconverted into kinetic energy by anefficient nozzle that forms a free jet.

The jet is unconfined and atatmospheric pressure throughout the

action of water on the runner and duringits subsequent flow to the tail race.

Blades are only on action when they

are in front of the nozzle.Water may be allowed to enter a partor whole of the wheel circumference.

The wheel does not run full and air hasfree access to the bucket.

Reaction turbine

Only the portion of the fluid energy istransformed into kinetic energy before

the fluid enters the turbine runners.

water enters the runner with an excesspressure, and then both the velocity andpressure change as the water passesthrough the runner.

Blades are in action all the time.

Water is admitted over thecircumference of the wheel.

Water completely fills the vanepassages throughout the operation of

the turbine.


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high vacuum requirements in

turbine operating High vacuum were important in turbine

operand because steam expansion number is

directly proportional with vacuum number inturbine.

Massive power can in achieve from expansion

in depression and the result very beneficial

than steam energy.


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Turbine speed control through

nozzle. When steam pass through nozzle, the velocitydepends on equilibrium condition or superheated.

In C3 figure, enthalpy (h) fight entropy (s) for steambalance expansion process through nozzle from

inlet pressure , P1 to outward pressure P2. At point a, steam in superheated condition, if

expansion happen by adiabatic frictionless inequilibrium condition, so steam will become

saturated dry at point b and become wet at point e. Steam has no opportunity to experience phase

change in during nozzle because expansion duringnozzle was too high.


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In C4 figure, steam is reheated to superheated,entry pressure P1 in a.

Due to development at b dropped too fast, steamcannot manage condensation on the other hand in asituation superheated vapour to point c

Constant pressure line, enthalpy entropy chart is acurve line for superheated steam. straight line onthe other hand for wet steam.

Imbalance characteristic of superheated steam not

remain long. at point c balance will happen fast. For addition , small increase of pressure at P4. that

state demonstrated at cd line.


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From point d, steam experience expansion inbalance to outward pressure, P2 at point e.

In this type of expansion, it alleges insupersaturated state.

At c state, it experience extreme cold.

Because of expansion happen by unbalanced sothat state called mestabil

Due to this, it is clear that the flow rate / steamspeed through nozzle in supersaturated

expansion found slightly higher than expansionflow rate in a situation balance. this due to theexist of the higher density result of morerefrigerant.


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Turbine speed control through

valve.

Valve is equipment which received inner

direction whether in form human (insani),mechanical, electric or pneumatic to releaseor stop or channel back air flow through it.


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Valve fall into 5 major type :

Check valve

Directioncontrol valve

Pressurecontrol valve

Combinedvalve

Flow controlvalve


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THERE IS 4 CHIEF METHOD HOWVALVE BEING MOVED.


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Governor.

A governor, or speed limiter, is a device used

to measure and regulate the speed of a

machine, such as an engine. for example, when engine burden increase,

engine speed will be diminished and currently

guard speed are going to act by adding fuel

supply in engine so that engine speedincrease to original magnitude.


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Types of governer


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Centrifugal governor working

principle. The centrifugal governors are based on the

balancing of centrifugal force on the rotating

balls by an equal and opposite radial force,known as the controlling force.

It consists of two balls of equal mass, which

are attached to the arms as shown in fig.

These balls are known as governor balls or flyballs.


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The balls revolve with a spindle, which is driven

by the engine through bevel gears.

The upper ends of the arms are pivoted to thespindle, so that the balls may rise up or fall downas they revolve about the vertical axis.

The arms are connected by the links to a sleeve,which is keyed to the spindle.

This sleeve revolves with the spindle but can

slide up & down.


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The balls and the sleeve rise when the spindlespeed increases and falls when the speed

decreases. In order to limit the travel of the sleeve in

upward and downward directions,two stops S, S

are provided on the spindle. The sleeve is connected by a bell crank lever to a

throttle valve.

The supply of the working fluid decreases when

the sleeve rises and increases when it falls.


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When the loads on the engine increases, theengine and the governor speed decreases.

This results in the decrease of centrifugal forceon the balls. Hence the balls move inwards and

the sleeve move downwards. The downward

movement of the sleeve operates a throttlevalve at the other end of the bell crank lever to

increase the supply of working fluid.


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Figure : Centrifugal governer

Balances Speed Controller

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