HYDROPOWER

1. Hydromechanical and
electro-mechanical
equipment
Prepared By:
Binu Karki
Lecturer
Msc.iWRM

2. Hydro-electric power plant
Working principle
 Hydro-electric power plant
utilizes the potential energy
of water stored in a dam
built across the river.
 The potential energy of the
water is used to run water
turbine to which the
electric generator is
coupled.
 The mechanical energy
available at the shaft of the
turbine is converted into
electrical energy by means
of the generator.

3. Hydropower????

5. Layout of Hydropower plant

6. Run of river hydropower

7. Run of river :micro-hydropower

8. Hydro-mechanical
installation in
powerhouse

11. Turbine: Definition
 The device in which the kinetic ,potential or
intermolecular energy held by the fluid is
converted in the form of mechanical energy
of a rotating member is known as a turbine
 Also , defined as all machines in which
hydraulic energy is transferred into
mechanical energy (in the form of rotating
shaft ) ,or in some other moving parts are
known as ‘turbines’ or hydraulic motors.

12. Working Principle of Turbine

14. Types of Hydroelectric
installation

17. Difference between Impulse and
Reaction turbine
Impulse turbine Reaction turbine
All available energy of fluid is
converted into kinetic energy by
an efficient nozzle that forms a
free jet.
Only a portion of fluid energy is
transformed into kinetic energy
before the fluid enters the runner
Unit is installed above the
tailrace
Unit is kept entirely submerged in
water below tailrace
Flow can be regulated without
loss of energy
Flow regulation is always
accompanied by loss of energy
Work-done is entirely due to
change in velocity
Work-done is due to change in
pressure and velocity
Turbine components are easily
accessible and repairs of
components are easy
Turbine components are not easily
accessible and repairs of
components are difficult
Suitable for high heads Suitable for relatively low heads
e.g. Pelton, Turgo turbine e.g. Francis, Kaplan turbine

18. Pelton, Francis and Kaplan
turbine

19. Pelton turbine

21. Pelton turbine

22. Components of Pelton turbine

26. Kaplan turbine video!!

27. specific speed, synchronous
speed and runaway speed of
turbine
 Specific Speed (Ns):
The specific speed is the speed with which the turbine
turns for a particular discharge Q, with unit head in order
to produce unit power. It is dimensionless quantity.
Ns=N 𝑃/H3/4
Where,Ns=dimensionless
N=speed of actual turbine
P=Power developed on shaft power,KW
H=Head under which turbine is working

28. Specific Speed for different
turbine
Specific speed Type of turbine
Less than 30 Single jet pelton turbine
30-50 Multi jet pelton turbine
50-260 Francis turbine
260-860 Kaplan turbine

33. Advantages of Kaplan turbine:
It can be used for the sites having very low Head.
Kaplan turbine has efficiency up to 90 percent
Because of small dimension of the power house there is
saving in excavation and civil Engineering works.
The frictional loss is less because of less number of blades.
Disadvantages of Kaplan turbine:
Leakage of water into generator chamber and condensation
are source of trouble.
Cost is very high for maintenance.

34. Applications of Kaplan turbine:
Kaplan turbines are widely used throughout the world
for electrical power production.
They cover the lowest head hydro sites and are
especially suited for high flow conditions.
Inexpensive micro turbines on the Kaplan turbine
model are manufactured for individual power
production with as little as two feet of head.
Large Kaplan turbines are individually designed for
each site to operate at the highest possible efficiency,
typically over 90%.
They are very expensive to design, manufacture and
install, but operate for decades.

37. Francis turbine animation

39. Francis Turbine

44. Bulb Turbine

45. Application of Bulb turbine: Tidal
power generation in England

46. Bulb/Tubular Turbine
 Tubular turbine is a reaction turbine of Kaplan type
which is used for lowest head.
 These are frequent for drops under 10m.
 In this turbine water flows with a mixed axial-radial
direction into the guide vane which are inclined at
normally 60o to the turbine shaft.
 Its runner is of the same design as the Kaplan turbine
runner.
 It is equipped with adjustable wicket gates and
adjustable runner blades .This arrangement provides
the greatest possible flexibility in adapting to changing
net head and changing demands for power output,
because the gates and blades can be adjusted to their
optimum openings.

47. Advantages of bulb turbine
 Reduction in runner diameter by about 15% as compared
to the conventional designs for a given discharge rating.
 Improved in efficiency as the losses are less
 Reduced danger of cavitation
 Smaller powerhouse dimensions for given output.
Elimination of spiral casing in this design contributes
greatly to space saving
 Comparative saving in civil engineering works as well as
other equipment as compared to conventional design.
 Bulb turbines are most suitable for tidal power plants
and for small hydro projects.

48. specific speed, synchronous
speed and runaway speed of
turbine
 Synchronous speed
If the turbine is directly connected to the generator, the
turbine speed N must be synchronous speed. For turbine speed
n to be synchronous, following equation must be fulfilled.
N=120f/Np
Where,
N=rotational speed
f= electrical frequency in hertz(take 50 Hz in Nepal)
Np=number of generator pole
 Runaway speed
The runaway speed of a water turbine is its speed at full flow,
and no shaft load. The turbine will be designed to survive the
mechanical forces of this speed. The manufacturer will supply
the runaway speed rating.

49. Factors governing turbine
selection
1) Specific speed:
 High specific speed is essential where the head is low and
output is large, because otherwise the rotational speed will
be low which means cost of turbo-generator and powerhouse
will be high.
 On the other hand there is practically no need of choosing a
high value of specific speed for high installations, because
even with low specific speed high rotational speed can be
attained with medium capacity plants.
2) Rotational speed:
 Rotational speed depends upon specific speed.
 Also the rotational speed of an electrical generator with
which the turbine is to be directly coupled depends on the
frequency and number of pair of poles.
 The value of specific speed adopted should be such that it
will give the synchronous speed of the generator.

50. Factors governing turbine
selection
3) Efficiency:
 The efficiency selected should be such that it gives the
highest overall efficiency of various conditions.
4) Part load operation:
 In general the efficiency at part loads and overloads is less
than that with rated (design) parameters. For the sake of
economy the turbine should always run with maximum
possible efficiency to get more revenue.
 When the turbine has to run at part or overload conditions
Deriaz turbine is employed. Similarly, for low heads, Kaplan
turbine will be useful for such purposes in place of propeller
turbine.
5) Cavitations:
 The installation of water turbines of reaction type over the
tailrace is effected by cavitations. The critical values of
cavitations indices must be obtained to see that the turbine
works in safe zone. Such values of cavitations indices also
affect the design of turbine, especially of Kaplan, propeller
and bulb types.

51. Factors governing turbine selection
6) Position of turbine shaft:
 Experience has shown that the vertical shaft arrangement is
better for large-sized reaction turbines, therefore, it is
almost universally adopted, whereas, in case of large size
impulse turbines, horizontal shaft arrangement is
preferable.
7) Available head and its fluctuation:
a) Very high (350m and above): For heads greater than 350m,
Pelton Turbine is generally employed and practically there is no
any choice except in very special cases.
b) High heads (150 m to 350 m): In this range either Pelton or
Francis turbine may employ. For higher specific needs Francis
turbine is more compact and economical than the Pelton
turbine that for the same working conditions would have to be
much bigger and rather cumbersome.

52. Factors governing turbine selection
c) Medium heads (60 m to 150 m): A Francis turbine is usually
employed in this range. Whether a high or low specific speed
would be used depends on the selection of the speed.
d) Low heads (below 60m): Between 30m to 60m both Kaplan
and Francis turbines may be used. Francis is more expensive
but yields higher efficiency at part loads and over loads. It is
therefore preferable for variable loads. Kaplan turbine is
generally employed less than 30m. Propeller turbines are
however, commonly used for heads up to 15m. They are
adopted only when there is practically no load variation.
8) Water quality(i.e. sand content ,chemical or other
impurities)
 Quality of water is more crucial in case of reaction turbines.
Reaction turbine may undergo for rapid wear in case of bad
water quality.

53. Turbine Selection

54. Turbine Selection

55. OPERATING ENVELOPE DIAGRAM

56. Design of Pelton turbine

57. Design of Pelton turbine

58. Design of Pelton turbine

59. Design of Francis turbine

60. Design of Francis turbine

61. Scroll Case, Draft tube an tailrace
canal and their importance
Scroll case:
A spiral-shaped steel/concrete intake guiding the flow into the
wicket gates located just prior to the turbine.
This maintains a constant flow rate despite the fact that
numerous openings have been provided for the fluid to enter the
blades, as the cross-sectional area of this casing decreases
uniformly along the circumference.
Functions of scroll case:
1.By providing decreasing area of casing in proportionate to the
volume leaving the casing ,the velocity of water is maintained
constant along the path.
2.To avoid loss of head scroll or spiral casing is provided
3.In low head up to 40m,concrete spiral case is provided but for
high head greater than 40m ,steel spiral case is provided.

62. Scroll Case, Draft tube an tailrace
canal and their importance
Draft tube:
A water conduit, which can be straight or
curved depending upon the turbine
installation, which maintains a column of
water from the turbine outlet and the
downstream water level.

63. Draft Tube

64. Draft Tube

65. Scroll Case, Draft tube an tailrace
canal and their importance
Tailrace:
The tail race, containing tail water, is a channel that
carries water away from a hydroelectric plant or water wheel. The
water in this channel has already been used to rotate turbine blades or
the water wheel itself. This water has served its purpose, and leaves
the power generation unit or water wheel area.
In hydroelectric dams, the tail race is at a much lower level than the
height of the reservoir behind the dam.

66. Electro-
mechanical
installation

68. Governing of Impulse turbine
 Governing in case of
impulse turbine is
regulation of quantity of
water rejected from nozzle
for controlling the speed of
turbine as load varies.

69. Governing of Impulse turbine
Parts:
 Oil sump with oil
 Relay/Control valve with piston/piston rod
 Cylinder with piston connected to
spear(servomotor)
 Impulse turbine
 Governor
 Nozzle
 Bell crank
 Oil pump
 Pipes connecting oil sump with control valve and
servomotor

70. Governing of Impulse turbine

71. Working principle of governors in
Francis(Reaction) turbines
Governing of reaction turbine is
related to
 regulation of water
rejected from guide vanes
and
 For controlling the speed of
turbine as the load varies

72. Working principle of governors in
Francis(Reaction) turbines
Parts:
 Reaction turbine with rotor and guide
vanes
 Oil sump
 Relay/control valve
 Cylinder with piston and linking
mechanism connected to guide vanes
which open and close guide vanes
 Governor
 Pipes connecting from oil sump to
control valve and then to cylinder with
linking mechanism

73. Working principle of governors in
Francis(Reaction) turbines

74. Motor Vs Generator

75. Introduction to generator and
their types
 Two types of generators are:
Synchronous generator:
They run isolated from the grid and produce power. They
are expensive than induction generator.
Asynchronous generator/Induction generator:
They run connected to the grid .

76. Introduction to Centrifugal
and Reciprocating pumps

77. Centrifugal pumps

78. Centrifugal Pump

81. Reciprocating pumps