1 selection criteria for turbine and drive krishna b. nakarmi

7/22/2019 1 Selection Criteria for Turbine and Drive Krishna B. Nakarmi

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TRUBINE AND DRIVE SYSTEM

Krishna B. Nakarmi

Krishna B. Nakarmi /UTSS 121st

April 2010


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Development steps on the

Turbine Manufacturing of Micro

Hydro Plants of NEPAL

.

21st

April 2010 2Krishna B. Nakarmi /UTSS


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3

Krishna Bahadur NakarmiMicro Hydro Consultant

IOE, CES

Project Coordinator

Technical Associates Addresses

Tel: 00 977 1 4244313

Email : kbnakarmi @ ntc.net.npResidence : 00 977 1 4276686,Post Box No.: 10996

21st

April 2010 Krishna B. Nakarmi /UTSS


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21st

April 2010 4

Professional Experience30 Years of experience in the Mechanical Field as aTechnical In-charge of Engineering Department atBalaju Yantra Shala (P) Ltd.

Hydropower Technology

Feasibility Study Designing of MHP equipment Supervision on production in the work shop Installation and Commissioning of equipment at

site .

Machine constructions, R & D of Mech. Devices,Repair and Maintenance, Any kinds of general services

Krishna B. Nakarmi /UTSS


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General Layout of MHP

521st



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Traditional Ghatta(Nepalise Indegenous Technology)

621st



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Water Mill (Ghatta)

Krishna B. Nakarmi /UTSS 721st

April 2010


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Improved Water Mill

821st



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Water mill with flour fortificationdevice

21st



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T1- CF Turbine

This model is a hand regulatedstraight forward design tomechanically drive a flat belttransmission for the operation ofagro-processing machineries such asflour-mill, rice huskers and oil

expellers etc.

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21st



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T1- turbine design

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T2- Turbine

This model is an attempt to come upwith a low cost design. The expensiveturbine housing is omitted to a large

extent. It result in having watersplashing all round the equipment,increasing the humidity in the mill

house and spoiling the flour. Thisdesign is obsolete.



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T3 - Turbine

This model is a compact design, andthe first machine with butterfly valvefor flow regulation. The bearingconcept is under design and notsuitable for outputs higher than20kW.

This design is modified to avoid thebearing problem that rotor can beremoved from the side flange.



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T3-turbine design



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Split flow Turbine

This turbine is designed for high headlow flow site and expecting it willhave high efficiency. But result showopposite way. So, stop productionand obsolete.



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Split flow turbine design



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T4 - Turbine

T4 model has a circular wing foe flowregulation. It was the first turbinewith automatic governor control usedin village electrification projects.



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T5 - Turbine

T5 model is basically the concept ofan enlarged T3 model. However themachine size was not adequate forthe production facility in Nepal. Thisdesign was phased out.



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T6- Turbine

T6 model suitable for governorcontrol, having a butterfly valve asthe flow regulating device. Thismachine is much stiffer thanprevious design, therefore has lowvibration and noise level during

operations. It is a good design forhigh specific discharge.



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T6-turbine design



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T7- Turbine

T7 is first model with fully machineturbine blades in order to increaseits efficiency. This advancedtechnology led to a runner failure dueto fatigue stress problem, so bladedesign was changed and used for

agro processing only.This model also recommended for 20kW plant only.



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T7- turbine design



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T8- Turbine

T8 model is the replacement of T7turbine in case of electrificationprojects. It is fully tested machine

with known characteristics. Thisallowed to define the applicationranges and to standardize the design.



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T8- turbine design



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T9 T11 Turbine

T9 T11 models are test model forthe following T12 Models. Allperformance tests were conducted atthe University of Hong Kong. Theefficiency hill diagram is the result ofthese tests. The design adheres to theconcept of the T8 series with themodified hydraulic profile and securedquality Control to guarantee theexchangeability of the spare parts.



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T12- Turbine

T12 model is the collection of pastexperiences, emphasizing longevity,rugged design etc. It used a newconcept to ventilate the jet (Free jetapproach) and is specially suited for

jet flow control. The main advantage

of this machine is good part loadefficiency as in full load.



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T12-turbine design



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T13- Turbine

T13 is the test model turbine. It ismade for testing purpose with fewmodifications on some parts. Theperformance result shows that theefficiency is increased by somepercent.



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T14- turbine design



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T15- Turbine

T15 model is the advance modelturbine with T 12 turbinecharacteristic and efficiency wise T14turbine. It is now being familiarthrough GTZ as T15 turbine inNepal.



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T16- Turbine

T16 model is developed with newconcept. It is basically upgradedversion model or combination of T7and T12 Turbine and few designparameters changed.This is not tested at any laboratory.But it is installed at existing plantwhere only turbine has to be replaced.



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T16

The client informed that they foundthe electric power output is increasedsignificantly. It means the turbineefficiency is increased. So the turbineefficiency can be guessed that itreached up to 78% to 80%



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T16

On the basis of this experience if theturbine components are madeprecisely the turbine efficiency canbe considered as 80%



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A Typical Cross Flow Turbine DesignDesign by: Krishna B. NakarmiModel: UTSS-08KBN/CF-03



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A typical Pelton Turbine DesignDesign by: Krishna B. NakarmiModel: UTSS-08KBN/PT-03

Krishna B. Nakarmi /UTSS21 st April 2010 38


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Uses of turbine1. Micro Hydro

Electricity Generating

Saw MillingHeat Generating Agro-ProcessingStone Crushing



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1. Selection of turbinePlant SizeLocally / ImportedSkill Man power for O & MEfficiency of TurbineCost of Equipment



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Working principle of differentturbines



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EXAMPLE (IMAGINARY SITE)SITE DATA

Gross Head H g 36 mDischarge Q l/s 600 l/s (AT Rriver)

Designed net head Hn = 32.4 m(Gross Head minus Pipe Lie Losses = 5 to 10 % H g)

Designed discharge Q = 480 l/s Available flow at river * 0.8 (80% of flow of the river)



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Turbine speed

Desired turbine speed is 1500 rpm.(Because normal gen. operating speed is 1500rpm)

Turbine speed depends upon the working pressure andselected turbine rotor diameter.



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Desired speed of the turbine n turb is 1500 rpm.( because operating speed of the commercialstandard alternator is 1500 rpm )

Turbine Speed to be calculatedBut the speed of turbine varies according to theavailable net head and selected turbine rotordiameter



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Turbine Specification(T12 / T15 CF Turbine)

Unit speed n 11 40 normally

Unit discharge Q 11 80

Efficiency of turbine 0.75

Turbine Rotor Diameter D 0.3 m

Rotor shaft Diameter d 80 mm



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(H m)0.5

n turb = 40* ----------Dm

(32.4 m)0.5

n turb = 40* -------------(0.3)

nturb

= 758.9 rpm



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Specific speed

(Q m3/s .)^0.5

n s = 3.65 * n turb rpm * ----------------(Hm) ^0.75

(0.480) ^ 0.5

n s = 3.65 * 758.9 * ------------------- = 141.3(32.4 0) ^.75

(REFERING THIS ns CROSSFLOW OR FRANCIS TURBINECAN BE SELLECTED)



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Hydraulic Power

Hnet * Q l/sP hy = -------------- (kW)

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32.4 m * 480 l/sP hy = ----------------- (kW)

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P hy = 152.4 kW(available power at the site)



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Plant efficiency ( plant )is determined as follows:

Electrical Power Output

P el = P hy * turb * trans * gen



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Turbine Efficiency

0.70 to 0.80 in case of Cross Flow

0.75 to 0.90 in case of Pelton / Francis



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Efficiency of transmission system(belt , coupling system)

= 0.9 to 0.95 in case of normal belts

= 0.95 to 0.98 in case of Habasit flat belt

= 0.98 to 0.99 in case of Flexible Coupling



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Efficiency of generator

= 0.76 to 0.92 in case of Synchronous Generator

( gen = 0.85 can be confirmed )



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Electrical power output

P turb = P hy * turb * Trans * gen

= 152.4 * 0.75*0.95*0.85

= 92.3 kW el

So, plant equipment efficiency can be determined to be 0.6 .



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5521 st April 2010

Thank You

1 selection criteria for turbine and drive krishna b. nakarmi

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