Design and Development of Intake Systems for HEPP

Conserve the Potential till the Entrance to Turbo-machine …….

P M V SubbaraoProfessor

Mechanical Engineering Department

Methodology of HEPP Development

• Site Survey: Hydrological & geological Survey.• Estimation of Potential• Regulations & Environmental Concerns• Feasible Supply• Turbine Selection• Costing and Payback.

River Characterization using Flow Duration Curve

Classification of Hydro Power Plants

• Runoff river plant (Diversion plant)• Storage plant (Impoundment plant)• Pumped storage plant• Tidal plant

Typical Arrangement of Natural RoR Hydro Plant

Creation of Reservoir

Creation of Reservoir : Srisailam

Height of Dam: 143.90mMaximum Depth of Reservoir : 214.76 mCapacity of the Reservoir: 8,700 M cum

Final Acceptable design of Srisailam Project

• Techno-economically viable capacity 1670 MW• Head Available : 91.46 m• No. of units : 7 + 6

Final Acceptable design of Srisailam ProjectSrisailam Right Bank Hydro Electric Scheme

Unit No Capacity(MW)

Date of Commissioning MakeTurbine Generator

1 110 30-08-1982    BHEL    BHEL   2 110 14-12-1982    BHEL    BHEL   3 110 19-11-1983    BHEL    BHEL   4 110 27-08-1984    BHEL    BHEL   5 110 31-03-1986    BHEL    BHEL   6 110 30-10-1986    BHEL    BHEL   

7 110 19-03-1987    BHEL    BHEL   770

Srisailam Left Bank Hydro Electric SchemenUnit No Capacity

(MW)Date of

CommissioningMake

Turbine Generator1 150 26-04-2001    Hitachi - Japan    Mitshubushi - Japan   2 150 12-11-2001    Hitachi - Japan    Mitshubushi - Japan   3 150 19-04-2002    Hitachi - Japan    Mitshubushi - Japan   4 150 29-11-2002    Hitachi - Japan    Mitshubushi - Japan   5 150 28-03-2003    Hitachi - Japan    Mitshubushi - Japan   6 150 04-09-2003    Hitachi - Japan    Mitshubushi - Japan   

900

The Power House

Global Layout of A Hydro Power Plant

Structure of Intake Systems

Power Tunnel:Diameter: 15000mmLength= 746mSlope= 1 in 120Actual velocity: 5.563m/s

Penstock

Intake Hydraulic Structures

• These structures include • Intakes;• Headrace channels; • Conveyance tunnels; • Penstocks; • Surge tanks; • Penstock manifolds;

Principles for the arrangement of the intake structure on the river

• With the discharge, each river entrains solid matter in the form of suspended matter or as bed load.

• The location of an intake structure must be so chosen that the largest possible portion of the bed load remains in the river and is not taken in the intake canal system.

• A satisfactory arrangement of the intake structure does not remove the suspended matter.

• To hold off the bed load the natural hydraulic behaviour of the river can be exploited through physical laws.

Physical Laws of Natural Rivers• Law 1: In straight sections of river or stream, the water

flows approximately in the cross-section of the channel, parallel to the banks.

• When the bed load transport begins, the bed load is transported accordingly on the bottom of the river.

• Law 2: In bends the direction of the bottom flow changes compared with the surface flow .

• A spiral flow forms which transports the bed load to the inner side of the river.

• On all streams and rivers it can be observed that gravel and sand banks form at the inside bend, i.e. the bed load is diverted from the intake bank.

Dynamics of Deposits in a river bend

Strategies to Enhance the life of Turbine

Intake from Straight River

Hydraulic Design of Intake Weir

Q = discharge over the downstream face in m³/s, c = correction factor for submerged overfall, μ =weir coefficient, b = weir crest width in m, g = acceleration due to gravity = 9.81 m/s², hü = weir head in m.

Global Layout of Intake system for HEPP

Structure of Intake Systems

Power Tunnels : Constant Pressure & Accelerating Flow

Power Tunnel

hgDfVS

24 2

0

Channel Bed Slope

PADh

4

High Pressure Piping : Penstock

General Design of Under Ground Power Tunnels

penstock

penstockfriction gd

fLVHxh

24 2

2

9.0Re74.5

7.3log

0625.0

hDk

f

Pipe Material Absolute Roughness, emicron

(unless noted)drawn brass 1.5drawn copper 1.5commercial steel 45wrought iron 45asphalted cast iron 120galvanized iron 150cast iron 260wood stave 0.2 to 0.9 mm

concrete 0.3 to 3 mm

riveted steel 0.9 to 9 mm

Estimate net Head available at the inlet of turbine casing

Optimum Diameter of Power Tunnel

• With increasing diameter, • the head losses and consequent energy losses in a power

tunnel decreases,• While construction cost increases.• The objection of economic analysis is to minimize total

annual costs.• Total cost consists of the annual charges from the

investment and monetary value of lost energy.

The energy lost per day

• The energy loss during particular day i, due to friction is:

ii

i tDfQE

5

3

7.0

• Energy loss, E• Darcy –Weisbach friction factor, f• Discharge through tubine system, Q• Duration of plant running, ti (h/day)

Monetary Loss due to Unavailable Energy & Annual Capital Cost

N

iii tQ

DfeML

1

357.0

Annual Capital cost:2DnCRFC

CRF : Capital Recovery Factorn= Economic scaling factor

Total annual cost, T = ML+C