types of hydro turbines

DIFFERENT HYDRO TURBINE TYPES AND

THEIR APPLICATIONS.

Group : 06

What is a turbine ?Rotary engine that exact energy from a fluid flow and convert in to useful work.Consists of rotor assembly with blades attached.Moving fluid acts on the blades.Water, Steam, Gas turbines….

Water turbine.Developed in the 19th century.Two types of water turbines.

o Reaction turbine.o Impulse turbine.

Turbine selection mostly based on available water head, less on water flow rate.

Reaction turbine.Water pressure drops when passing through

the turbine wheels.i.e. increase the kinetic energy.That energy transfer to the turbine wheels. Have a housing to contain the water

pressure.Used in low and medium head applications.

Reaction turbine runner.

Impulse turbineWater is injected to the turbine by nozzles.That high velocity water jet impact with

curved turbine blades which change the direction of water flow.

That change in momentum(impulse) creates a force on the blades, which causes to spin the turbine runner.

No pressure change occurs at the turbine blades. So turbine needn’t a housing.

Used in very high head applications.

Impulse turbine runner

Francis turbineDeveloped by James B. Francis.Type of inward flow reaction turbine.Most common water turbine type.Water inlet is spiral shaped.

Francis Inlet Scroll, Grand Coulee Dam

Francis turbine cont….Wicket gates direct water tangentially to the

turbine wheels.Water flow is controlled by adjusting wicket

gates.

Francis turbine cont…Efficiency is typically over 90%.Efficiency is reduced with flow rate.Can be used with 20m-700m water heads.Output power may vary from just a few kWs

to 1 GW.During law power demand this can be used as

a pump to fill the reservoir.

Graph

Francis turbine cont…Francis turbine employed PS in Sri Lanka.

PS Rated Power(MW)

Water Head(m)

Kothmale 3*67 227-189

Victoria 3*70 208-140

Randenigala 2*61 84-51

Rantambe 2*24.5 33.73-22

Ukuwela 2*20 89.39-70.1

Bowatenna 1*40 52.73-44.8

Wimalasurendra

2*25 227.4-245

Canyon 2*30 198.2-222

Polpitiya 2*37.5 259-265

Samanala Wewa

2*60 300-341

Kukule Ganga 2*40 140

Kaplan turbineDeveloped by Viktor kaplan in 1913.Evolution of Francis turbine, but

revolutionized ability to develop the low head hydro sites.

Propeller type inward flow reaction turbine that has adjustable blades.

Used in high flow, low head power production.

Operation of Kaplan turbine

Kaplan turbine cont…Efficiency can be improved by varying the

geometry of wicket gates and turbine blades for a range of flow conditions.

Efficiency is typically over 90%.Lower in very low head Applications.

Graph

Efficiency Vs Water Head

Kaplan turbine cont…Udawalawe PS employs Three kaplan turbine

units.(water head is 13m and rated power is 2MW per unit).

Because propeller blades are rotated by high pressure hydraulic oil, positive seal must provided to prevent emission oil to the waterway.

Pelton wheel turbine…Invented by Lester Allen Pelton in 1870.Impulse type water terbine.Most efficient type of water turbine.

Plan view of a Pelton turbine

Pelton wheel turbine cont…Used in relatively high water heads with low

flow rate.To get maximum power and efficiency, the

velocity of water jet should twice as the turbine runner periphery.

used mostly in mini and micro hydro power plants.

Can be run even in light loads efficiently, which does not occur in Fracis or Kaplan turbines.Grap

h

Pelton wheel turbine cont…Pelton wheel turbine employed PS in Sri

Lanka

PS Rated power(MW)

Water head(m)

Old Laxapana 2*12.5 472.5-476.7

New Lakxapana

2*50 518-527

Nilambe 2*1.6 113.3-107.7

Erathne mini hydro

2*5.15 450

Turgo turbineDeveloped in 1919 by Gilkes as a modification

of the Pelton wheel.Impulse type water turbine.Operates in head ranges where francis and

Pelton wheel overlap(i.e. medium head).Populer for small hydro projects.Runner is less expensive than Pelton wheel.Runner is one half times larger than a same

power pelton wheel runner.

Turgo turbine cont…

Efficiency Vs Flow Rate

Francis

Kaplan

Pelton

Selection of Turbine.

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