GAZIANTEP UNIVERSITY

FACULTY OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING

HYDROPOWER ENGINEERINGWATER CONVEYANCE SYSTEM

Submitted by: KHABAT STAR MOHAMMED

MARIF MAHMOOD KARIM

ISRAR NAJAT JABBAR

YASIR SHAKIR MAHMOOD

Submitted to :

Doç.Dr.Aytaç Güven

Water Conveyance system

Introduction

Any structure that conveys water from

one location to another.

Hydropower Block Diagram

Water resource

Head work

Storage head work

Dam

Diversion head work

Weir Barrage

Plan ( 1 )

Dam, weir or barrage

Tunnel

Surge tank

Open channel or power canal

Fore-bay

Intake Directly form U/S

Penstock Power house

Surge tank Some time

River again

Plan ( 2 )

Intake

Definition of diversion head work

A structure constructed across a river to raise the

normal water level and drive the required supply

in to main canal or power canal

Diversion Head work

Fig. ( 1 )

Components of diversion

head work1. Barrage or weir

2. Canal head regulator

3. Divide wall

4. Fish ladder

5. Under sluice portion

6. Silt excluder

7. Marginal bunds

8. Guide bank

Weir Barrage

Canal head regulator

Function of head work

1. A head work raises the water level in the

river.

2. It regulates the intake of water into the canal.

3. It also controls the entry of silt into the canal.

4. A headwork can also store water for small

periods of time.

5. Reduces fluctuations in the level of supply in

river.

What is intake

A hydraulic-engineering installation for obtaining water from a source of supply (river, lake, reservoir, and so on) for purposes of hydroelectric power engineering, water supply, or irrigation.

amounts, of the proper quality, and according to a water-consumption or demand

Intake

Elements of intake

1. Trash rack and supporting structure.

2. Smolt screens.

3. Bell mouth entrance.

4. Gate slot closing devices with air vents.

5. Ice, log trash boom.

6. Silt excluders and silt ejectors.

7. Under sluices.

1- Trash rack

2- screen • A trash rack is a wooden or metal structure, that

prevents water-borne debris (such as logs,

boats, animals, masses of cut waterweed, etc.)

from entering the intake of a water mill,

pumping station or water conveyance. This

protects penstock, and sluice gates from

destruction during floods..

• Usually positioned in forebay or intake structure.

Trash Rack

Trash rack Trash rack

Removing or cleaning process to

trash rack

Smolt Screen

3- Bell mouth entrance

.

4 – gate slot closing It is control regulates the entry of water into the intake.

Gates

5- ICE,LOG,AND TRASH

BOOMS

Floating boom use to perform one or more of the

following functions

1. Deflection of logs and trash from the intake

screens.

2. Deflection of ice away from the intake.

3. Prevention of the boats form being carried into

the intake

Trash Boom .

6- silt excluders and silt ejectors

• Silt Control Devices

A. Silt Excluder: The silt excluder is located on the u/s of diversion weir and in front of the head regulator and the object is to remove silt that has entered in the stilling basin through scouring sluices.

B. Silt Ejector: Silt Ejector is located in the canal take off from the diversion weir at 6 to 10 km in the canal reach and it ejects the silt that has entered in the canal

Silt control

Silt excluder Silt Ejector

LOCATION OF INTAKE The various factors influencing the choice of location of intake structure are:

1- Type of storage reservoir

2- Location and type of dam/weir

3- Type of water conductor system that is canal or tunnel

4- Topographical features of the river.

5- should not be located on curves or at least on shape curves

6- should remain easily accessible during floods.

7- located at place from where can draw water even during the driest period of the year

TYPE OF INTAKE

•Depending on the function served and the range in

reservoir head under which it is to operate,

•The discharging capacity and frequency of the reservoir

drawdown, intake for hydroelectric projects or more

elaborate structure raised as a tower above maximum

reservoir level.

Type of Intake Intake

a- According to type of source

River intake

Reservoir intake

Canal intake

Lake intake

b- According to position of intake

Submerged intake

Exposed intake

c- According to presence of water in the

tower

Wet intake

Dry intake

PLAN ( 3 )

A- According to source

1- River Intake

River intake

2- Reservoir intake

3- Lake intake

4 - Canal intake

B- According to position of intake

• An Intake structure which remains entirely under water during its operation is termed as submerged intake.

• It is provided where the structure serves only as an entrance to the outlet required.

• The conduct intake may be inclined, vertical or horizontal in accordingly with the intake requirements.

• An inclined intake may be provided with gates and operated on the upstream slopes of a low dam.

1-submerged intake

submerged intake

2- Exposed intake

• Is in the form of well or tower constructed near

the bank of river or in some cases even away

from the bank of river, they are more common

due to ease in operation and maintenance .

Exposed intake

C – According to presence of water in

the tower

• In dry intake tower the entry ports are directly

connected with the withdrawal conduit and water

inside the tower when gates are in a closed

position.

• Dry Intake tower has a merit that the intake tower

being dry is made accessible for inspection and

operation besides that the water can be withdrawn

from any level by opening the port at that level.

1- Dry intake tower

2- Wet Intake Tower

• A wet intake tower has entry ports at various levels and

the vertical shaft is filled with water up to reservoir

level.

• It differs from the dry intake tower is that the water

enters from the ports into the tower and then into the

withdrawal conduct through separate gated openings.

Wet intake tower

Wet intake tower

QUALITY WATER

1- Location of intake is required to be such as to draw

the best quality of water from the reservoir.

2- Depth of water at intake is important.

3- Quality of water varies at different levels in the

reservoir and it is necessary to draw water from

different elevation of the reservoir at different

seasons of the Year for which multi-level intakes

are frequently provided.

OPTIMUM WATER UTILIZATION

1- Intake is located in the deepest part of the impounding

reservoir to enable full utilization of capacity of reservoir

and to protect intake from sediments in the reservoir.

2- In the reservoir with wide variation in the water level.

3- The intake is better located at the lowest stage so that

one inlet is always submerged and operative to draw

supply and minimum operating head is always available.

Water conveyance system

The main components are :

A. Open channel flow

system

B. Pressure flow system

Open channel flow and pressure flow systems

What is Open channel?

A covered or uncovered conduit in which

liquid (usually water) flows with

its top surface bounded by the atmosphere. Typical

open channels are

rivers, streams, canals, flumes, or

sewers, and water-supply or hydropower aqueducts

Classification of open channel

Based on :

1. shape

2. natural / artificial (man made)

3. change in cross section and slope

4. boundary characteristic

Classification based on a shape

1.Rectangular

2.Trapezoidal

3. Triangular

4. semi-Circular

5.Parabolic

6.Compound

Trapezoidal open

channelRectangular

open channel

semi-circular

open channel

Triangular

open channel

Compound open

channel

Parabolic

open channel

Open channel geometric relationships for varies cross-section

Classification based on

• Natural channel

All watercourses that exist naturally on the earth like Brooke ,creeks , tidal

• Artificial channel

Those constructed to perform various project requirements and termed canals

Flumes , culverts

Natural channel Artificial channel

Classification based on change in

slope and cross sectionPrismatic : a channel in which cross section shape

and size also the bottom slope are constant , most of

man-made channels(artificial) are prismatic channels

like rectangular ,trapezoidal , triangular ,circular

channels

• Non – prismatic : slope or cross section

changes, all natural channels generally have varying in cross section and consequently are non- prismatic.

Classification based on boundary

characteristic

Mobile boundary channel Rigid boundary channel

Forebay

• A forebay is an artificial pool of water in

which located before and connected with

penstocks

• Provided in case of run-off- river plants

• The major use of forebay was to distribution

Flow of water in to penstocks , store water

which is rejected by hydropower plant

, Containing a trash rack and bye-pass channel.

Forebay connecting with penstock and

Containing a trash rack and bye-pass channel

Forebay in nature

Trashrack that which used to prevent undesirable

material (planate , dead animals) for entering to

penstock that may choke the system

BANK AND CHANNEL

PROTECTIVE LINING Lining are Protective layer artificial or natural

material which placed in a channel bottom and

banks that may be used to:

• prevent erosion resulting from high velocities

of water

• breaking down resulting from entering water

in Cracks and gaps

• shapely appearance and proper

Lining classification

The main classifications of open channel linings are based on the material which that covered the channel and we have two items :

• Rigid Linings

• Flexible linings

Rigid Linings

Rigid linings are generally constructed of

concrete, pvc, or concrete blocks pavement

they are more expensive , prevent

infiltration and Require periodic

maintenance

whose smoothness offers a higher capacity

for a given cross-sectional area and Higher

Velocities

The following are examples of Rigid

Linings:

Pri –cast concrete channel

concrete blocks channel Pvc channel

Flexible linings

Flexible linings have several advantages compared to

rigid linings They are generally less expensive,

permit infiltration and exhilaration and can be

vegetated to have a natural appearance, have self-

healing qualities which reduce maintenance

In many cases flexible linings are designed to

provide only transitional protection against erosion

The following are examples of Flexible linings:

Grasses or natural vegetation

Grass linings are suitable for applications where they will be

exposed to periodic relatively slow flow of water

This type of lining has a pleasing appearance,

is economical and is not subject to damage as a result of

undermining or settlement of the supporting soils

Rubble riprap

Wire-enclosed riprap

B:Pressure flow system1- Low-pressure conduits and tunnels

2- High-pressure conduits, commonly called the

penstocks

TunnelsTunnels can be designed as underground passages

made without removing the overlying rock or soil.

TBM: also known as a "mole", is a machine used to excavate

tunnels with a circular cross section through a variety of soil and

rock strata. They may also be used for micro tunneling. They can

bore through anything from hard rock to sand.

Layout of a tunnel alignmentThe first aspect that needs to be decided for a tunnel is the

alignment .

Hydropower tunnel•

Hydraulic tunnels can be divided

into the following categories:1- Pressure tunnels

2- Free flowing tunnels

Depending on their shape, tunnels may be classified as:

1- D-shaped

2- Horse-shoe shaped

3- Circular shaped

4- Egg Shaped and Egglipse Sections

Tunnel section

Cross – section of a tunnel depends on the

following factors:

1- Geological conditions prevailing along the

alignment,

2- Structural considerations, and

3- Hydraulic requirements,

4- Functional requirements.

D-SHAPED SECTION:• D-shaped section is found to be suitable in tunnels located

in good quality, intact sedimentary rocks and massive

external igneous, hard ,compacted , metamorphic rocks

where the external or internal pressures.

Horse-Shoe sectionThis sections are strong in their resistance to external pressure. Quality of rock and

adequate rock cover in terms of the internal pressure to which the tunnel is subjected

govern the use of these sections. This section offers the advantage of flat base for

constructional ease and change over to circular section with minimum additional

expenditure in reaches of inadequate rock cover and poor rock formation.

Note: For tunnel excavated to horse -shoe section

and concreted to circular section.

Modify horse shoe section

Egg Shaped and Egglipse Sections• Where the rock is stratified soft and very closely laminated (as

laminated sand stones, slates, micaceous schists , etc) and where the

external pressure and tensile forces in the crown are likely to be high

so as to cause serious rock falls, those sections should be

considered.

Circular sectionThe circular section is most suitable from structural consideration. It is

difficult to excavation where cross-sectional area is small. In case where the

tunnel is subjected to high internal pressure, but does not have good quality

of rock and/or adequate rock cover around it. circular section is considered

to be most suitable.

Steel supports These are built of steel sections, usually I-sections, either shaped or

welded in pieces in the form of a curve or a straight section

Installing steel supports

ROOF BOLTS OF ROCK• Rock bolts were used to support the roof and walls of major structures

such as tunnels and power stations

• These steel bolts, of different length and spacing, were inserted into the

rock where they were found to be an excellent anchorage for the rock.

Tunnel Lining• Tunnel linings: main types. Tunnel linings are grouped into three

main forms some or all of which may be used in the construction of a tunnel.

• Temporary ground support

• Primary lining

• Secondary lining

• Temporary ground support: In rock tunnels where the ground has insufficient stand-up time to allow the construction of the primary lining some distance behind the face.

• Primary lining. A primary lining is the main structural component of the tunnel support system which is required to sustain the loads and deformations that the ground may induce during the tunnel's intended working life.

• Secondary lining. Various tunnels require smooth bore profiles for their intended use, eg sewer and water tunnels or aesthetic finishes for public usage, eg highway and pedestrian tunnels.

Arch steel support

Shotcrete in tunnel

Tunnel Grouting: This is a cement mortar with

proportion of cement, sand and water in the ratio 1:1:1 by weight

usually, though it may be modified suitably according to site

conditions.

types of grouting:

• Back-fill grouting :to fill spaces between initial lining and

rock.

• − Contact grouting: to fill gaps between initial lining and plug

concrete.

• − Consolidation grouting: to improve the quality of the

surrounding rock.

• − Curtain grouting: To preventing water seepage from the

waterway end portion.

• Grouting

• Grouting process

• Pattern of Holes for Grouting

• Backfill or Contact Grouting - Backfill grouting is limited to the arch portion of the tunnel. The number of holes normally three in each section, the pattern being staggered in each subsequent sections located 3 m center to center.

Consolidation or Pressure Grouting -• Consolidation grouting is done to consolidate the shattered rock

all around the cavity. The pattern of holes is such that these are distributed all along the periphery but staggered in alternate sections space 3 m center to center. The number of holes may be four for smaller tunnels six for bigger tunnels.

Consolidation or Pressure Grouting 6

holes

What is surge tankSurge tank is located between the headrace pressure conduit

and the steeply sloping penstock pipe and is designed either as

a chamber excavated in the mountain or as a tower raising high

above the surrounding terrain.

The main functions of a surge tank are:• Reduces the amplitude of pressure

fluctuations by reflecting the incoming

pressure waves.

• Improves the regulating characteristics of a

hydraulic turbine because; it reduces the

water starting time of a hydropower scheme.

• Surge tanks, which are used to dissipate

water hammer pressure

Water Hammer

• Water Hammer is a pressure surge or wave that

occurs when there is a sudden momentum change

of a fluid (the motion of a fluid is abruptly forced

to stop or change direction) within an enclosed

space (Water Hammer).

• This commonly occurs in pipelines when a valve

is closed suddenly at the end of a pipeline where

the velocity of the fluid is high. The pressure

wave created will propagate within the pipeline.

Depending upon its configuration, a surge tank may be

classified as follows;

• 1- Simple surge tank: A simple surge tank is a shaft

connected to pressure tunnel directly or by a short

connection of cross-sectional area not less than the area of

the head race tunnel.

2- Orifice surge tank: if the entrance to the surge tank

is restricted by means of an orifice, it is called an orifice

tank.

3- Differential surge tank: an orifice tank having a

riser is called differential tank.

4-Closed surge tank:If the top of the tank is closed and there is compressed air between the water surface and the top of the tank, then the tank is called closed surge tank, a tank with air cushion.

5-Surge Tank with Spilling Chamber

PENSTOCK

What is penstock ?

•A penstock is one of the parts of conveyance system that

construct from a steel or reinforced concrete to resist high

pressure in the water conveyance system

• What is the Function of penstock?

• It’s function is conveying water from for bay

or surge tank to the turbine in the power hous

and it’s help to increase the kinetic energy of

water that comes from the end of head race.

Type of penstock

1. Buried penstocks 2. Exposed penstocks

Buried penstocks:

are supported continuously on the soil at the bottom of a trench

backfilled after placing the pipe. The thickness of the cover over

the pipe should be about 1.o to 1.2 m.

Advantage:• The soil cover protects the penstock against effect of

temperature variations,

• It protects the conveyed water against freezing.

• Buried pipes do not spoil the landscape.

• They are safer against rock slides, avalanches and falling

trees.

Disadvantage:

• the inspection and faults cannot be determined easily.

• It’s installation expensive Especially For large diameters and

rocky soils.

• On steep hillsides, especially if the friction coefficient of the

soil is low, such pipes may slide.

• Maintenance and repair of the pipe is difficult.

are installed above the terrain surface and supported on piers

(briefly called supports or saddles). Consequently, there is no

contact between the terrain and the pipe itself, and the support is

not continuous but confined piers.

Advantage:• The possibility of continuous and adequate inspection during

operation.

• Its installation is less expensive in case of large diameters of

rocky terrain.

• Safety against sliding may be ensured by properly designed

anchorages.

• Such pipes are readily accessible and maintenance and repair

operations can be carried out easily

Exposed penstocks:

Disadvantage:

• Full exposure to external variations in temperature.

• The water conveyed may freeze.

• Owing to the spacing of supports and anchorages

significant longitudinal stresses may develop especially

in pipes of large diameters designed for low internal

pressures

Design of penstock:

• According to the Bureau of Indian Standards code IS: 11625-1986 “Criteria for hydraulic design of penstocks” The determination of penstock diameter based on the following losses may be expected for a penstock:

a. Head loss at trash rock .

b. Head loss at intake entrance .

c. Friction losses, and .

d. Other losses as at bends, bifurcations, transitions, values, etc.

Bends

Depending on topography, the alignment of the penstock is often

required to be changed, in direction, to obtain the most

economical profile.

Reducer piece:

In the case of very long penstocks, it is often necessary to reduce the diameter

of the pipe as the head on the pipe increases. This reduction from one

diameter to another should be effected gradually by introducing a special

pipe piece called reducer piece.

Branch pipe: Depending upon the number of

units a single penstock feeds.

Expansion joints :are installed in exposed penstocks to prevent longitudinal expansion or contraction when changes in temperature occur.

Manholes: Manholes are provided in the course

of the penstock length to provide access to the

pipe interior for inspection, maintenance and

repair.

Bulk heads: Bulkheads are required for the purpose of

hydrostatic pressure testing of individual bends, after

fabrication, and sections or whole of steel penstock and

expansion joints, before commissioning. Bulkheads are

also provided whenever the penstocks are to be closed

for temporary periods, as in phased construction.

Air vents and valves: These are provided on

the immediate downstream side of the control gate or

valve to facilitate connection with the atmosphere.

How hydropower

system work ?

• Tailraces:

After passing through the turbine the water

returns to the river trough a short canal called a

tailrace.

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