PENSTOCK THICKNESS CALCULATION (CASE STUDY )

A hydroelectric plant is planned to be built by utilizing the waste water from the reservoir of 3.5 m3 / s, which flowed into a penstock with a diameter of 1600 mm and the thickness (e) 9 mm. As you know, the more thick penstock then the price will also be more expensive.

Try to analyze whether the specifications of the pipe can still be revised, especially for the thickness of pipe used, whether the thickness can be reduced to (e) 6 mm, thus decreasing the cost of piping.

Existing data:

• The material used is Mild steel ( rolled welded steel pipe)
• The diameter of the pipe /penstock (Dp) = 1.6 m (1600 mm)
• Pipe thickness (e) = 9 mm(which will be in the analysis)
• Penstock length (Lp) = 66 m
• Flow of water (Qp) = 3.5m3/det
• High gross ( H gross) = 7.3 m
• Head Loss (H loss)= 0.3 m
• Net Head = 7 m
• Water velocity in thepenstock (V) = 1.74 m / s
• Efficiency of penstock (pipe eff) = H net /  H gross * 100% = 96%
• visc µ = 0.00114 kg / (m.det)
• Density of  water = 1000 kg/m3
• K (bulk modulus of water) = 2.1*10^9 N/m2
• ts (Tensile strength pipe) = 400 * 10^6 N/m2
• E (modulus of elasticity) = 206 * 10^9 (N/m2)
• In this design, penstock is used having a thickness (e) = 9 mm

Working pressure (P work) of the penstock (Mild steel )
 The desired pressure of 1.5 * Gross Head (Hg)

Note: ...[3]

The addition of pressure on the penstock :

Head up to 50 m is not more 50%

Head of 50 to150 is no more than 25%

Head up to 250 m is not more 15%

Then :
Working pressure (P)   = 1.5 *  7.3  = 10.95 m
                                    = 1.5 * (7.3 / 10) = 1.095 kgf/cm2 (Bars)
                                    = 1.095 kg/cm2 *10000 cm2/m2 * 9.81 m/s2
                                    = 107,419 N/m2 (pascal)
                                    = 107,419 N/m2 * (kN/1000N) * (m2/1000000 mm2)
                                    = 0.000107419 kN/mm2

The formula for a thin tube ( if  Dp / e > 20)...[3]
Where:
e     = thickness of penstock in mm
es    = extra thickness for corrosion (1-3 mm )...[3]
Working pressure (P) = 0.000107419 kN/mm2
Dp = diameter of 1600 mm penstock
ts (Tensile strength)  = 400* 10^6 N/m2
                               = (400 * 10^6 N/m2) * (kN/1000N) * (m2/1000.000 mm2)
                               = 0.400 kN/mm2
Minimum penstock thickness (e)
e = (P * Dp) / (2 ts) + es...[2]
        Taken extra thick for corrosion es) = 3 mm
e = (0.000107419 kN/mm2x 1600 mm) / (2 x 0.400 kN/mm2) + 3 mm
e = 3.21 mm

Check the use of penstock thickness formula
Category of penstock used , Dp / e = 1600 / 3.21
                                                      = 498 > 20 (a thin tube, the formulas is ok)

The impact of pipe handling in transportation, laying, deformation, etc., it is necessary to add more rapidly the penstock thickness (in the wills of 3 mm). So thick of penstock (e) is = 3+3.21= 6.21 mm, the thickness of the penstock taken at least 6 mm (see the availability of the thickness of the penstock in the market)

Effect of Water Hammer
In the design of penstock also must take into account the effects of water and control the speed lacing.

If the H / L> 5, the surge tank is required ...[1]
In this design:
H / L   = H gross / length of pipe (L)
           = 7.3 / 66
           = 0.11 < 5
 (Not required surge tank but the effects of  water hammer still be calculated)
The thickness of the penstock (e) = 6 mm is to be used

At wills:
% Closure of the valve flow (z) = 50%
With the closing time (T close)  = 4 seconds (fast enough)
Corrosion allowed (es)             = 3 mm
Overall safety factor (SF)         = 4

Calculation:
The speed of water waves:
C wave = [(10^ (-3)* K) / (1 + (K* Dp / E* e)]^ (0.5) ...[2]
where:

• K = bulk modulus of water 2.1x10^ 9 N/m2
• E = modulus of elasticity of pipe material 206 * 10^9 (N/m2)
• D = pipe diameter 1600 mm
• e = wall thickness 6 mm
• L = length of pipe, 66 m

By entering values:
C.wave         = [(10^(-3)* 2.1*10^9) / (1 + (2.1*10^9 x 1600 / (206 * 10^9 * 6)] ^0.5
                    = 751.5 m / s
Critical closing time of the penstock (Tc) 

The time it takes the pressure wave (pressure wave) to return again to the valve after the sudden closure, known as the critical time.

Tc = 2 L / C...[2]
     = 2 x 66 m / 751.5 m / s.
     = 0.716 seconds
T.Close  (4 sec)> Tc  (0.716 sec)... [4]

Kc   = L* z * V / ( g * Water density * H.gross *  T Close)
        = 66 m * 50 * 1.74 m / s / (9.8 * 1000 kg/m3 m/s2 * 7.3 mx 4 s)
        = 0.2
Surge pressure (H.surge )...[4]

H.surge       = H gross * [(Kc / 2) + ((Kc + (Kc^2 / 4)) ^0.5]
                  = 7.3 * [0.2 / 2 + ((0.2 + (0.22/ 4))^ 0.5
                  = 4.07 m
H.total        = H.surge + H.gross
                  = 4.07 m + 7.3 m
                  = 11.37 m (exceeds the pressure of work, a total of 11.37 m >P work 10.95 m)

For a Total Head ( H.total ) of 11.37 m , the required minimum thicknessof the penstock (e)
e     = (H.total * Dp * SF / 83700) + es
       = (11.37 m * 1600 mm * 4 / 83700) + 3 mm
       = 3, 87 mm ( penstock with a thickness of 6 mm is adequate)

Ref :

1. AHEC/MNRE/SHP Standards/ Civil Works –  Guidelines For Layout Of Small Hydro Plants /Feb 2008. (p-77)
2. ESHA (European Small Hydropower Association),”Layman’s Handbook on How To Develop a
   Small Hydro Site,”2nd ed, 1998 (p-144/145)
3. Patty O.F., Tenaga Air, Erlangga, Jakarta1995 (p-62/64)
4. STEEL PENSTOCK LOSSES & THICKNESS CALCULATION (p-1)
   http://www.energyservices.lk/pdf/techspecs/vh_w_b/pensteel.pdf

Design of the cross flow runner

The equations in this section are taken from:

• Arter, A., Meier, U., Harnessing Water Power on a Small Scale Hydraulics Engineering Manual(SKAT)
• Mockmore, C. A. Prof CEng, Merryfield, F. Prof CEng, The Banki Water Turbine, 1949
• Harvey, A, Micro Hydro Design Manual, (1993), ISBN 1-85339-103-4

Download PDF

Permanent Magnet Generator (PMG) Construction Manual

Hugh Piggott - Scoraig Wind Electric - February 2001

This manual describes how to build a 'permanent magnet generator' (PMG). We can also call it an 'alternator', because it generates alternating current (AC). It will not generate 'mains voltage' or 'utility power' AC. It generates low voltage, 'three phase' AC, and then changes it into 'direct current' (DC) for charging a 12 volt battery.

Download Pdf

Hydraulic losses in a penstock

Hydraulic losses in a penstock reduce the effective head in proportion to the length and approximately as the square of the water velocity.

Here you can download the way of calculation in xls

SLING PUMP

Written By : Lance Brown

This pump is commonly known by its commercial name of Sling Pump. It is based on a principle similar to the Archimedean screw, except it operates in a horizontal position with coiled pipe, rather than a sloped and open screw.

Read More

Crossflow Water Turbine Design Manual

By ; Abhiroop Chattopadhyay

The crossflow water turbine is widely considered by many to be the most efficient and apt type of turbine for applications in micro‐hydro and picohydro projects. However, it should also be noted that designing this kind of a turbine is no child’s play.Nevertheless, in this article, I will show you exactly how the designing of the turbine is to take place. With a very basic knowledge of mathematics, it is possible to design and construct an efficient working water turbine. Before, designing, just get an idea about how must hydraulic power is theoretically available at a particular site.

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The breastshot waterwheel: design and model tests

By: G. Muller and C. Wolter

The waterwheel is one of the oldest hydraulic machines known to humankind and has been in use since antiquity. Originally built of wood, the availability of new materials, namely wrought iron, and the increasing demand for mechanical power during the industrial revolution led, in combination with the development of hydraulic engineering, to the rational design of waterwheels, resulting in much increased performance and efficiency. Three distinct types of waterwheels evolved: the overshot, the breastshot and the undershot wheel.

Overshot wheels were investigated quite thoroughly and were found to have efficiencies of more than 85% for a broad range of flowrates from 0.2 to 1.0 Q/Qmax. Only one measurement of an undershot or Zuppinger wheel is known to the authors. Researchers from the Technical University of Stuttgart in 1977 measured the efficiencies of a 42 kW Zuppinger wheel which was built in 1886 and had been in continuous operation since. The measurements showed efficiencies of 71–77%. The breastshot wheel however, which was particularly popular in Britain,was never investigated. Read more

Speed control of run-of-river variable speed hydro plants

By : J. Fraile-Ardanuy1, J. R. Wilhelmi, J. Fraile-Mora, J. I. Pérez and I. Sarasúa

The advantages of adjustable speed hydroelectric generation have been highlighted by several authors. The optimum speed for actual working conditions must be continuously implemented by means of an appropriate control system. This process gives rise to dynamic changes in operation variables. In this paper a speed control of run-of-river adjustable speed hydro plant is presented.

Read more (pdf)

Calculation of Kaplan turbine / propeller

By Ahmad Suhendra

In this post, we present an example calculation of pipelines, power generators, turbines in the form of Exel spreadsheets.

download xls

Building an Undershot Water Wheel

http://www.builditsolar.com

By Gary

An undershot wheel is a vertically-mounted water wheel that is rotated by water striking paddles or blades at the bottom of the wheel. The name undershot comes from this striking at the bottom of the wheel. This type of water wheel is the oldest type of wheel.

Downloads :

Building an Undershot Water Wheel (Pdf)

Waterwheel design xls

SMALL MICHELL (BANKI) TURBINE

SMALL MICHELL (BANKI) TURBINE:

A CONSTRUCTION MANUAL

BY

W.R. BRESLIN

The Michell or Banki turbine is a relatively easy to build and highly efficient means of harnessing a small stream to provide enough power to generate electricity or drive different types of mechanical devices.

Read more

The documents required in the construction of hydroelectric power in Indonesia

Did you know?

How many documents are needed for the construction of mini-hydro power plant in Indonesia?

The documents required in the construction of hydroelectric power in Indonesia, quite a lot and cumbersome and therefore has not seen government efforts to accelerate the utilization of renewable energy.

1. Principles of forestry land use permit from the Ministry of Forestry.
2. Principle permit replacement of land forest from the Ministry of Forestry.
3. Official recommendation of the Energy and Mineral Resources. (Provincial level).
4. Recommendations from the Governor
5. Principle permit the use of land forest (from the Province).
6. Permit principle of Regents.
7. Utilization and land use permits (IPPT)
8. Principle permit the use of land forest from the Regent.
9. Building permit (IMB)

And many more documents are needed.

Application of micro hydro power plant in Indonesia

By Ahmad Suhendra

Scheme "on the grid" is less attractive to investors because the electrical energy produced by microhydro or minihidro power plant valued more cheaply by PLN (in Java Rp 432/kWh) than the electrical energy produced by other sources (eg fossil) , resulting in payback period becomes longer than 5 years. Also invested too risky, because the rate of environmental degradation (forest), which is high at 1.08 million hectares per year that could threaten the availability of water for the survival of micro hydropower plant so that the old design is not achieved. For the scheme "off the grid" there are still opportunities for investors because they do not have to sell electricity to PLN, but directly to consumers, particularly for rural areas that are not grid.

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Wind Turbines

This book is concerned with the subject of wind energy, as source of clean and renewable and free for all. The need for this type of book is very well documented, the current consumption of energy is unsustainable and humans have to change their habits and or utilise this source, but there is so much work before we can rely completely an renewable energy. This book aims to describe the fundamentals of wind energy and the pertinent parameters that control the amount of energy available from given win turbine.

Wind Turbines
(c) 2010 T.Al-Shemmeri & Ventus Publishing ApS
ISBN 978-87-7681-692-6

Benchmark prices in the Framework of Power Purchase Accelerating Indonesia's Energy Diversification

The benchmark prices of the Power Purchase are as follows :

(According to the Minister of Energy and Mineral Resources Regulation No. 044 of 2006)
Prices are stated in U.S. dollars

• 4. 95 U.S. cents / kWh for capacity to 25 MW per-unit;
• 4.75 U.S. cents / kWh for capacity > 25 MW sd 150 MW per-unit;
• 4.50 U.S. cents / kWh for capacity > 150 MW per-unit.

Or prices set by the Electricity Basic Tariff (Tarif Dasar Listrik/TDL)

• 70% of TDL to capacity to 25 MW per-unit;
• 65% of TDL to capacity> 25 MW to 150 MW per-unit;
• 60% of TDL to capacity> 150 MW per-unit.

Note:

Power purchase price may change if there is agreement between both parties regarding changes to the indicator, inflation, factors generating capacity, and coal prices.

Conclusion:

1. Purchase price of electricity set by the Government is the highest benchmark price.
2. While the amount of the contract is an agreement of both parties according to the mechanism of Bussiness to Bussiness.
3. The benchmark price setting process is "bottom-up", which is based on the proposal of PT. PLN (Persero).
4. Power purchase price adjustment is possible, as long as agreed by both parties and stated in the contract of sale of electricity.

Download Electricity Basic Tariff 2010 (Tarif Dasar Listrik/TDL)

Ref :
http://www.elektroindonesia.com/seminar/20080814/dirjen-lpe.pdf

GUIDELINES FOR BUSINESS ELECTRICITY IN INDONESIA

For those of you who will do business power in Indonesia for a small or medium then you should know the basic laws and regulations that exist in Indonesia.

Photo by Departemen Energi dan Sumber Daya Mineral

News of the Republic of Indonesia No: 46 of 2009
MINISTER OF ENERGY AND MINERAL RESOURCES
REPUBLIC OF INDONESIA NUMBER: 05 OF 2009

Business guide for small-scale Power Generation and spread in Indonesia
MINISTER OF ENERGY AND MINERAL RESOURCES
NO: 1122 K/30/MEM/2002
June 12, 2002

Micro Pelton Turbines E.Book

If you want to make micro Pelton turbines , then you must read this e-book as a reference. This publication (e-book ) has its origin in a workshop on "Micro hydro power energy", organized by GATE, which was held in Eschbom, Germany. The aim of the workshop was to discuss relevant experience in planning and implementation of very small hydro power plants in developing countries, to determine problems and deficits in the technical and socioeconomic fields and to discuss masters on direct utilization of mechanical power. One of the deficits stated at this workshop concerned micro Pelton turbine installations.

Niederuzwil, September 1991
Markus Eisenring

Read E.Book

Saddles, supporting blocks and expansion joints

By Ahmad Suhendra

The saddles are designed to support the weight of the penstock full of water, but not to resist significant longitudinal forces. The vertical component of the weight to be supported, in kN, has a value of :

F1 = (Wp + Ww) * L Cos θ
where :
Wp = weight of pipe per meter (kN/m)
Ww = weight of water per meter of pipe (kN/m)
L = length of pipe between mid points of each span (m)
θ = Angle of pipe with horizontal

The design of support rings is based on the elastic theory of thin cylindrical shells. The pipe shell is subject to beam and hoop stresses, and the loads are transmitted to the support ring by shear. If penstocks are continuously supported at a number of points, the bending moment at any point of penstock may be calculated assuming that it is a continuous beam, and using the corresponding equation. The rings are welded to the pipe shell with two full length fillet welds and are tied together with diaphragm plates.

The span between supports L is determined by the value of the maximum permissible deflection L/65000. Therefore the maximum length between supports is given by the equation:

L= 182.61 * [(Dp + 0.0147)^4 - Dp^4)]^(1/3) / (Wp + Ww)

Example :
What is The vertical component of the weight to be supported if such data is given below:

1.Diameter of pipe (Dp) = 0.636 m
2.Pipe thickness (e) = 0.005 m (5 mm)
3.Density of pipe (ρ steel) =7.9 ton/m^3
4.Density of water (ρ water) = 1 ton/m^3
5.Angle of pipe with horizontal (θ )= 5 deg


I. Wp (weight of pipe per meter)
= phi * ( Dp + e) * e * ρ steel
= 3.14 (0.636 + 0.005)* 0.005 * 7.9
= 0.079 ton/m

II. Ww (weight of water per meter of pipe)
= [(phi x ( Dp^2) / 4] * ρ water
= [(3.14 x 0.636^2)/4] * 1
= 0.32 ton /m

III. Total weight (Wp + Ww)
= 0.399 ton/m (Wtotal)
= 0.399 * 9.81
= 3.914 kN/m

IV. The maximum length between supports.
L= 182.61 * [(Dp + 0.0147)^4 - Dp^4)]^(1/3) / (Wp + Ww)
= 182.61 * [(0.636 + 0.0147)^4 - 0.636^4]^(1/3) / (3.914)
= 182.61 * [0. 01566 ]^(1/3) / (3.914)
= 182.61 *[0.2502]/3.914
= 11.67 m

V. The vertical component of the weight to be supported.
F1 = (Wp + Ww) * L Cos θ
=3.914 kN/m * 11.67 m* Cos 5
= 45.503 kN

Ref :
ESHA (European Small Hydropower Association),”Layman’s Handbook on How To Develop a Small Hydro Site,”2nd ed, 1998 http://www.scribd.com/doc/8885765/Layman-Handbook-for-hydro-electric-power-plants

Photo
http://www.fr.aps-sales.com/documentos/downloads/HydroPower%20and%20penstock%20applications.pdf

Sebintang River (0 36 22.4N ; 113 02 41.7E) in West Borneo, Indonesia

The Choice of Materials For Water Turbines

Photo by Ahmad Suhendra

Determination of material for water turbine is very important, because turbines work on conditions such as high pressure, abrasion caused by sand carried by the flow, and also of pH levels and salinity that can cause corrosion, so that the appropriate materials needed to treat the condition. There are several types of water turbines and materials used in their manufacture.
Penentuan bahan untuk membuat turbin air sangatlah penting, karena turbin bekerja pada tekanan tinggi, adanya pengikisan karena pasir yang terbawa air , juga derajat keasaman (pH air) dan kadar garam dalam air yang dapat menyebabkan korosi, maka untuk itu diperlukan bahan yang tepat untuk mengatasi hal tersebut.
Disini diperlihatkan beberapa jenis turbin air dan bahan yang digunakan untuk membuatnya.

Read More

Ref:
http://www.ivt.ntnu.no/ept/fag/tep4200/innhold/The%20choice%20of%20materials.pdf