mechanical equipment-narrative (1)

7/31/2019 Mechanical Equipment-Narrative (1)

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6.3. Hydromechanics and Mechanics Equipment

Introduction

Based on the data from the hydro-construction part of the project, to facilitate the

production of the mechanical part of the project, the following startup data are

derived:

Installed flow of the power plant

Qinst=18 m3/s

Installed flow of the bigger aggregate 14,5

m3/s

Installed flow of the smaller aggregate 3,5

m3/s

Elevation of normal slow

194,50 mnm

Elevation of the lower water for the installed flow 191,75

mnm

Number of aggregates 2

(bigger and smaller)

Losses in the flow tractHg=0,2 m (In consideration

taken losses in siphons

output,

while the rest of losses are

of inconsiderable size)

For the provided downfalls, of around 3 meters, the priority is given to the

tube-axial- aggregates, comparing to the rest aggregates types. Intoconsideration are taken 3 types of tube aggregates:

Classical tube turbine has been discarded because of the small diameter of the

impeller (not recommended if the impellers diameter is less than 3 meters)

S-turbine has been discarded because of the mechanicals construction size


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BEVAL-GEAR tube turbine, which has been accepted as the best solution for

both aggregates (see the picture below)

Picture 1: An example of the tube turbine BEVAL-GEAR

construction

Axial turbines can be effectively used in the small hydro-electric plants, as

per requests in the terms of flows (power) variation, they can be managed tohave double regulation regulation by the blades of the rotating field and by

the blades of pilot machine.

As hydro-turbines for the small downfalls have small rotating frequency, in the

most frequent use within the axial-turbines is the multiplicator, with a purpose

of use a standard generator, with its economic justified rotating frequency.

2. Basic equipment in the mechanical construction

Biserka, hydro-electric plants mechanical construction, is a dam type.

Dimensions of the mechanicals construction base are defined: by the

geometry of the turbines flow parts, by quantity of the equipment and by

the areas, which is needed to set on the various appropriate elevations:

turbines, generators, head covers, electric tables and cupboards, and

supporting machines based on the adequate norms and rules. Outside

dimensions of the mechanical hall are 12.25m x 20,17m. Inside the


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mechanical building dimensions of 11,25m x 13,80m, there are two turbines

aggregates situated, of the 4,70m axis spacing.

Montage space has not been anticipated, yet the aggregates will be handled

by the boom truck through the holes on the mechanical constructions roof.

2.1. Turbine

The tube turbines have been chosen, with the conic multiplicator and dual

regulation: regulation by the blades of impeller and by the blades of pilot

machine. In such a way, a wide range of turbine work is covered with optimal

range of usefulness, though turbine and turbines regulator are slightly more

expensive.

Basic technical data of bigger turbine:

the type of turbine tube

(BEVEL-GEAR)

type of generator

(synchronus)

nominal downfall 2,55 m

maximal downfall 3,29 m nominal flow 14,5 m3/s

minimal flow 3,6 m3/s

number of the rotating frequency 111,87min -1

diameter of impeller cca. D1=2,10 m

nominal turbines power 334 kW

expected level of the turbines efficiency in the normal working point

0,925

Basic technical data of smaller turbine:

the type of turbine tube

(BEVEL-GEAR)

type of generator


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(synchronus)

nominal downfall 2,55 m

maximal downfall 3,31 m

nominal flow 3,5 m3/s

minimal flow 1 m3/s number of the rotating frequency 250 min -1

diameter of impeller cca. D1=1,0 m

nominal turbines power 80 kW

expected level of the turbines efficiency in the normal working point

0,91

The main units of the both turbines types, smaller and the bigger are:

penstock valve

stator with pilot machine

impeller

impeller housing with siphons cone

turbine housing

The penstock valve is made of concrete, whose right angled pipe section is of

dimensions: in the bigger 3.40m x 6.24m and 1,70m x 1,80m in the smaller

aggregate and shift to the circuit, of the diameter 3,40m (bigger aggregate) i

1,70m (smaller aggregate). Intakes dimensions are defined in such a way,

that the stream speed through the lattice, on the water well is of

approximately 1 m/s. A cavity is done just in the vertical direction, by the

hydraulic shaped grasp, yet the sideways are vertical. Stator of the turbine is

joined with the penstock valve, and by the flanges, with the armature of the

impeller.

On the upstream part of the stator are stairs for the leaning on the concrete

panels implemented into bearer concrete pillars.


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The impellers housing and cone of siphon are one complex, divided

horizontally, because of the turbines montage of the impeller and joined with

turbines stator on the upstream side, and with the siphon on the downfall

side. It has been constructed of the stainless steel in the zone of runners

blades.

Upper leg of the siphon is ribbed, of the steel construction which can be

divided horizontally as well. It leans on the concrete panels and pipes. On the

lowest elevation of the siphon is a drainage sink-hole for the soaking-out.

In the parallel processing of the hydro-electric plant and the network, the

upper water level is kept on the 194,50 mnm elevation, yet the water

energy has been transformed to electricity which has been placed into

distribution. The excess water which inflows to the hydro-electric plant andcant be transformed to the power, overflows through spillways.

Productive aggregates in the parallel processing with the network, work

automatically without permanent human input. Beside that, turbine i.e.

generator could be conducted locally and from the turbine i.e. generator

control apparatus.

Fast blocking (shutdown) of aggregates is needed:

if the cyclic shift goes excessively which is a protection of

runaways

if a hydrodinamic lubrication stops, and a water flows stops in the

supporting machines and

if the pressure in the hydrodinamic lubrication declines to some

point.

2.2. Equipment of turbine regulation


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Based on the feature of a small hydro-electric plant in the electrical

network, the level of automation, turbine category and system flow, as well

as the consumers characteristics, the most profitable choice of the control

equipment has been made.

a) Mode and type of regulation

Within the parallel functioning of aggregates with a large electrical network,

a regulator performs to the turbines regulatory organs. Regulatory

quantities are:

level of the upper water

potency of aggregate

the flow through turbine

b) Basic technical requirements for the turbines control apparatus

Regulation system of the hydro-aggregates with the tube turbine (i.e. when

the blades of directed apparatus and impellers are regulated) is based on

the combinatorial conjunction.

Equipment of the turbines regulation has to fulfill the following main

functions:

startups sequences and shutdowns of the turbine and supporting

machines

setting and descent of the regulatory loading

aggregate shutdown following the security measures signals

Control apparatus must have a facility of the manual conduction on themechanism for startup and mechanism for shifting aggregates power.

Apparatus for the rotation frequency speed control must to provide a stable

regulation within the functioning of aggregate namely:

in the idle motion when the generator is disconnected from the network


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without loading or with loading up to 10%, for the supply of private

consumption consumers

in the idle motion parallel with the network

Within load changes

Rotating frequency regulator is acting by hydraulic system within oil-

lubrication under pressure. Regulatory system of turbine must have enough

standby energy within all working strokes, to ensure expected regulation and

turbines shutdown in the emergency case. Regulation speed response, which

determinates quality of regulation, is needed to adjust with characteristics of

water flow system and impetus aggregates volumes. This process will ensure

required safety and operation reliability of small hydro-electric plant.

System of turbine regulation is made of device for the rotating frequencyspeed, programmable logic controllers (PLC), hydroelectric governor system

and unit for the turbine pump oil-lubrication.

Programmable logic controller is situated in the cupboard of hydro-electric

power and its delivery is included in the equipment supply. Sensors for the

level measuring in the accumulation, outflow, rotation frequency and the

placement of servo motors pistons, are included as well in the shipment of the

controller.

Electro hydraulic-managing unit of the regulator, accommodate the

elements; they operate servo motor of the pilot machine and impeller, in theaccordance with orders from digital regulator; pilot dividing valves

(commensurable valves) are involved for automatic-continual operating with

servo motors, and electro-magnetic and hydraulic commanded valves, for

common average shutdown.

Device for the oil-lubrication under pressure is anticipated, for both

aggregates, and is made of steel reservoir for oil, two operating and one

spare oil-pump fitted on the reservoir, oil-hydraulic accumulator, pipeline and

pipe fittings. Pressure level of oil-installation would be accordingly

maintained to a standardized technical solution of equipment distributor, for

the pressure of 100 bar or more.


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Mechanism of pilot machine is equipped with contra-weight which acts in the

case of trapped blades (one or more) of pilot machine.

2.3. Multiplicator

To increase a number of the rotating frequency turbine to a number of

synchronic generator, it is anticipated conic one-level multiplication.

a)Bigger aggregate:

Inlet number of rotation 111,87min -1

Outlet number of rotation 750 min -1

Expected level of efficiency 0.96

Multiplicator number 1

a) Smaller aggregate

Inlet number of rotation 250 min -1

Outlet number of rotation 1000 min -1

Expected level of efficiency 0.96

Multiplicator number 1

2.4. Supporting equipment in mechanical construction

2.4.1 Drainage and discharge

Equipment for drainage of mechanical construction and equipment for

discharge of water flow are implemented to one complex.

Oozed waters through the walls of hydro-electric plants and turbines are

collected by gravitational drainage watercourses, and carried on into drain

hole; the hole that is situated on the lowest elevation of mechanical

construction. From this drain hole, by the pipeline, water goes to the

cumulative drain outflow of mechanical construction.

Drainage of pre-turbine chamber is done by grasp on the penstock valve and

the concrete part of concrete pipeline; on the spot where pipeline penetrates

into hydro-electric plant, is flat gate valve, operated manually. Siphons


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drainage is done through grasp on the lowest point of the siphon, by steel

concrete pipe. On this pipe is flat gate valve. Via pipeline system, water goes

gravitationally to the cumulative drain outflow and by pumps, there, is

soaking-out of the outflow turbines tract. Drainage and soaking-out of the

outflow of the turbine tract, is done by one or two pumps for each of

aggregates. Each pump has separated pipeline with back circuit. Soaking-out

of back-circuit is to the tailwater, downfall of the siphon head-cover, above

the reservoirs elevation. (hundred years high water)

2.4.2. Hitting and aeration

It is not required to warm up mechanical construction with extra energy

sources, for the minimal positive temperature in nominal working conditions,

considering that generators release heat in the working phase, by dissipation.

To maintain hitting in the winter period which is needed for equipment

service in the mechanical building (screenings, repairs, breakups, etc.) while

generators are not in drive, it is anticipated to have plug box for an electric

hitter.

While summer, mechanical building is aerated naturally via gateways of waste

heat, in the generators working phase. For that purpose, is lattice maintained on

the outside wall, above the entrance of mechanical construction.

2.5. Hydro-mechanical equipment of

mechanical construction

2.5.1. Inlet lattice

Lattice prevents penetration of floating objects (traversals, wood, plastic bottles,

etc.) inside the turbine. It is consisted of two panels, whereas each of them has

strips, in the brazing process mutually, solidly coupled with transversed girders.

Basic technical data of lattice of bigger aggregate:

Lattice width 3.9 m

Lattice height 6.5 m

Elevation sill lattice 187.47 mnm

The upper elevation in front of lattice 194.50


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Bevel of lattice toward horizontal level 85

Number of segment 2

Gaps between strips 80 mm

Dimensions of strips 80 mm x 10

mm Number of lattice 1

Basic technical data of lattice of smaller aggregate:

Lattice width 1.97 m

Lattice height 3.2 m

Elevation sill lattice 188.60 mnm

The upper elevation in front of lattice 194.50

Bevel of lattice toward horizontal level 85

Number of segment 2

Gaps between strips 50 mm

Dimensions of strips 70 mm x 8 mm

Number of lattice 1

2.5.2. Upstream multi-pieced head-cover

On the entry of penstock valve, beside the inlet lattice in the upstream

direction, is recess situated, for the rigging of head-cover. Its feature is to

prevent water inflow into the turbines flow tract, if turbine is under screening or

repair. The head-cover is multi-pieced, paneled shape (stop-log). It can be lifted

and lowered by boom-truck of adequate capacity.

Basic technical data of head-cover of bigger aggregate:

Type of head-cover Multi-pieced paneled


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Width of light hole 3.91 m

Height of light hole 6.10 m

Elevation of head-covers sill 187.50 mnm

Elevation of platform for 197.00 mnm

Manipulation Boom truck Number of head-cover 1

Basic technical data of head-cover of smaller aggregate:

Type of head-cover Multi-pieced paneled



Elevation of head-covers sill 188.60 mnm

Elevation of platform for maintaining 197.00 mnm

Manipulation Boom truck

Number of head-cover 1

2.5.3 Siphons head-cover

For the purpose of water isolation from the downfall side of hydro-electric

plant, in cases of screening and repair of turbine flow tract, siphons head-

cover is anticipated. Head-cover has been lifted and lowered by bridge crane.

While the normal turbines work, head-cover is always in complete open

degree, and is situated in concrete slideways.

A siphons head-cover is without an automatic shutdown possibility and the

protection of turbines move off, as the lower price and considering the type

of hydro-electric plant, of relatively small power. To provide intervention in

emergency cases (in the case of canceled shutdown by pilot machine), the

head-cover needs an access capability into waters power by its own weight,

under all levels of upper water. In this sense, stopping plate of head-cover

would be from the downfall side, while the head-cover itself, would be hard

with needed overweight.

Basic technical data of head-cover of bigger aggregate:

Type of head-cover Paneled with wheels




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Elevation of head-covers still 188.01 mnm

Elevation of platform for maintaining 197.00 mnm

Elevation of lower water with Qinst=18 191.75 mnm

Nominal flow through head-cover 14,5 m3/s


Basic technical data of head-cover of smaller aggregate:

Type of head-cover Paneled with wheels



Elevation of head-covers still 188.01 mnm

Elevation of platform for 197.00 mnm

Elevation of lower water with Qinst=18 191.75 mnm

Nominal flow through head-cover 3,5 m3/s


mechanical equipment-narrative (1)

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