Presentation Main Turbine

7/31/2019 Presentation Main Turbine

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MAIN TURBINE

SPECIFICATION:

MAKE : BHELDESIGN :KWU, GERMANY

TYPE :THREE CYLINDER REHEATCONDENSING,SINGLE FLOW BARRELTYPE CASING,IP&LP DOUBLE FLOW WITH

2&3AXIAL SPLIT CASING RESPECTIVELY

STAGES :HPT 1x17 REACTION STAGESIPT 2X12 REACTION STAGESLPT2X6 REACTION STAGES

VALVES :HPT 2 MAIN STOP&CONTROL VALVESIPT 2 RH STOP& CONTROL VALVESCRH LINE-1 SWING CHECK VALVELP BYPASS 2 STOP &CONTROL VALVE

LOAD SHARING :HP 26%, IP 34%, LP 40%


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GENERATOR EXCITER

1 2 34 5 6 7

TURBINE LAYOUT

Fromboiler ESV1 CV1

CRH

HP BYPASS

IPSV1 IPCV 1

CONDEN

FROM RH

LPBYPASS

TO LP HEATERS

HPT 1X17IPT 2X12 LPT 2X6


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HP TURBINE

The HP turbine has 2 main stop valves and 2 control valves located symmetricallyto the right and left of the casing .The main steam is admitted through the main steam inlet passing first the mainstop valves and then the control valves. From the control valves the steam passesto the turbine casing.The HP outer casing is designed as a barrel-type casing without axial joint .

Because of its symmetrical construction, the barrel-type casing retains itscylindrical shape and remains leak proof during quick changes in temperature (e.g.on start-up and shut down, on load changes and under high pressures.The inner casing, too, is almost cylindrical in shape and axially split.

The inner using is attached in the horizontal and vertical planes in the barrel-typeusing so that it can freely expand radially in all directions and axially from a fixedpoint when heating up while maintaining concentricity relative to the turbine rotor.

On the admission side, four projections of the inner casing and on the exhaustside three projections into corresponding grooves in the barrel.


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TURBINE BLADES

MOST COSTLY ELEMENT OF TURBINE

BLADES FIXED IN STATIONARY PART ARE CALLED GUIDEBLADES/NOZZLES AND THOSE FITTED IN MOVING PART ARE CALLEDROTATING/WORKING BLADES.

BLADES HAVE THREE MAIN PARTS

1. AEROFOIL: WORKING PART2. ROOT3. SHROUDS

SHROUD ARE USED TO PREVENT STEAM LEAKAGE & TO GUIDE STEAMTO NEXT SET OF MOVING BLADES.


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HP TURBINEThe HP turbine balding consists of 17 drum stages.

All stages are reaction stages with 50% reaction.

The stationary and moving blades of all stages are provided with inverted T-roots, whichalso determine the distance, between the blades. The shrouds are machined integralwith the blades and forms a continuous shrouding after insertion.

The moving and stationary blades are inserted into corresponding grooves inthe shaft and inner casing and are caulked at bottom with caulking material.

The insertion slot in the shaft is closed by a locking blade ,which is fixed by grub screws.


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Shaft Seals and Balance Piston

FUNCTION:The H P turbine has shaft seals in front and rear. The front shaft seal islabyrinth type,while the rear shaft seal is see through type. The function of these shaftseals is to seal the interior of the casing from the atmosphere at the ends of the shaft on

the admission and exhaust sides. The difference in pressure before and after the raisedpart of the shaft seal on the admission side serves to counteract the axial thrust causedby steam forces. The effective seal diameter is suited to the requirements for balancing

the axial thrust.

GAP SEALS : Sealing between the rotating and stationary parts of the turbine is

achieved by means of seal strip caulked into seal rings and into the rotor.SEAL RING: The seal rings the number of which depends on the pressure gradient tobe scaled are divided into several segments, mounted in T-shaped annular grooves inthe inner casing and shaft seal cover. In the region subjected to the low relativeexpansion in the vicinity of the combined journal and thrust bearing, the seal strips arecaulked alternately into the shaft and into spring-supported segmented seal rings in the

casing, forming a labyrinth to impede the outflow of steam.In the region subject to greater relative expansion at the exhaust end, see through sealsare used. in which the seal strips are located opposite each other, caulked into the Shaftand into seal rings cantered in the outer casing.STEAM SPACES: Steam spaces are provided within the shaft seals.For HP turbineconnection is given to IP/LP crossover, seal steam supply header and gland steam

condensor.


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Front Bearing PedestalArrangement : The front bearing pedestal Is located at the turbine-side end of theturbine generator unit. Its function is to support the turbine casing andbear the turbine rotor. It houses the following components and instruments:

Journal bearing Hydraulic turning gear Main oil pump with hydraulic speed transducerElectric speed transducer Over speed trip Shaft vibration pick-up

Bearing pedestal vibration pick-up.

The bearing pedestal is anchored to the foundation by means of anchor bolts. Theanchor bolt holes are filled with gravel, which gives a considerable vibration dampingeffect.Lubricating oil is admitted to the bearing shells from one side and flows to oil spacesthat are milled into the upper shell at the horizontal joint and are open to the rotor. Therotor picks up oil from oil pockets machined into the babbitting.


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Rear Bearing Pedestal

Arrangement: The bearing pedestal is located between the HP and IP turbines. Itsfunction is to support the turbine casing and bear the HP and IP turbine rotors. Thebearing pedestal houses the following turbine components:

Combined journal and thrust bearing Shaft vibration pick-up Bearing pedestal vibration pick -up Thrust bearing trip (electrical).

Oil Supply: Lubricating oil is admitted to the bearing shell, fro, one side via oil linefrom where it flows to the oil spaces milled into the upper and lower bearing shellsat the hi joint. Oil leaving the journal bearing flows to the two annular groovesadjacent to the bearing surface and then to the thrust pads. Through the two returncowlings, is discharged into the drain area in the pedestal.

Passages are located at the lowest point in the lower bearing shell through whichhigh pressure jacking oil is supplied ' ed under the journal at low speed of the.turbine reef (on start-up or shutdown)


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CASING SUPPORT& FIXED POINT

The turbine casing Is supported on the support horns such as to make allowance forthermal expansion. It is essential for the casing to retain concentric alignment withthe rotor, which is supported independently.The turbine casing is supported With its two front and two rear support horns on thehorn supports of the bearing pedestals.

Fixed Point: The fixed point for the turbine casing is located at the rear horn supporton HP-IP pedestal at the turbine centreline level and is formed by the parallel keys.


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IP Turbine

Casing : The casing of the IP turbine is split horizontally and is of double-shellconstruction. Inner casing is supported in the outer casing.

Steam from the HP turbine after reheating enters the inner casing from top andbottom through two admission branches which are integral with the mid section ofthe outer casing.

This arrangement provides opposed double flow in the two blade sections andcompensates axial thrust.

The provision of an inner casing confines the steam inlet conditions to the admissionsection of this casing, while the joint flange of the outer casing is subjected only tothe lower pressure and temperature effective at the exhaust from the inner casing. Inthis way, difficulties arising from deformation of a casing with flange joint due to non-uniform temperature rise, e.g. on start-up and shut-down, are avoided.


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IP TURBINE

INNER CASING ATTACHMENT

Due to the different temperatures of the inner casing relative to the outercasing, the inner casing is attached to the outer casing in such a manner as tobe free to expand axially from a fixed point and radially in all directions, whilemaintaining the concentricity of the inner casing relative to the shaft.

In the horizontal plane, the four support horns of the top half inner casing reston plates. which are supported by the joint surface of the bottom half outercasing. The shoulder screws are provided with sufficient clearance to permitthe inner casing to expand freely in all directions in the horizontal plane. Thesupport horns provided at the bottom half inner casing, project into therecesses in bottom half outer casing with clearance on all sides.


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IP TURBINE

MOVING & STATIONARY BLADES

The IP turbine balding consists of 12 drum stages in each steam flow direction. Allstages are reaction stages with 50% reaction. The stationary and moving blades ofall stages are provided with inverted T-roots, which also determine the distance

between the blades. All these blades are provided with integral shrouds, which afterInstallation form a continuous shroud.

The moving am stationery blades are inserted grooves in the rotor and in the innercasing and are bottom caulked with caulking material . The insertion slot in therotor is sealed by a locking blade, which is fixed by grub screws.


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GAP & SHAFT SEAL : The function of the shaft seals is to seal the interior of theturbine casing against the atmosphere at the front (thrust bearing end) and rear shaftpenetrations of the IP turbine.

In the region subject to low relative expansion in the vicinity of the combined journaland thrust bearing, the seal strips are caulked alternatively into the shaft and intospring-supported segmented rings in the casing, forming a labyrinth to impede theoutflow of steam.

In the region subject to greater relative expansion at the exhaust end, see-throughseals are used, in which the seal strips are located opposite each other, caulked intothe shaft and into seal rings cantered in the Outer, casing.

Sealing between the rotating and stationary elements of the turbine is achieved bymeans of seal strip caulked into seal rings and into the rotor.

Steam Spaces Steam spaces are provided within the shaft seals. One connectionis drawn off to the steam seal header. The slight amount of leakage steam which arestill able to pass the seal ring are conducted from the space into the seal steam

condenser.

IP TURBINE


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The bearing pedestal is located between the IP and LP turbines. Its function is tosupport the turbine casing and bear the weight of IP and LP rotors.

The bearing pedestal houses the following turbine components:

Journal bearing

Shaft vibration pick -up Bearing pedestal vibration pick -up Hand barring arrangement Differential expansion measurement device

The bearing pedestal is aligned on the foundation by means of hexagon headscrews that are screwed into it at several points. On completion of alignment, thespace beneath the bearing pedestal is filled in with special non-shrinking grout.The bearing pedestal is anchored to the foundation by means of anchor bolts.The anchor bolt holes are filled with gravel, which gives a considerable vibration

damping effect.

IP TURBINEREAR BEARING PEDESTAL ARRANGEMENT


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CASING SUPPORTS & FIXED POINTS

The turbine casing is supported on the support horns such as to make allowance forthermal expansion. It is essential for the casing to retain concentric alignment with the

rotor, which is supported independently .

The turbine casing is supported with its two front and two rear support horns on thehorn supports of the bearing pedestals at the turbine centreline level. This arrangementdetermines the height of the casing and also allows thermal expansion to take place inthe horizontal plane by the support horns sliding on the sliding pieces of the bearingpedestals.

The fixed point f or the turbine casing is located at the front horn support at the turbinecentreline level and is formed by the parallel keys . Axial expansion of turbine casingoriginates from this point.

IP TURBINE


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LP TURBINE

The LP turbine casing consists of a double flow unit and has a triple shell welded

casing.Steam admitted to the LP turbine from the IP turbine flows into the inner casing fromboth sides.The LP casing has a double-flow inner casing. This inner casing is a double shellconstruction and consists of the outer part and the inner part. The inner shell is

suspended in the outer shell to allow thermal movement and carries the front guideblade rows.

The rear guide blade rows of the LP stage are bolted to the outer shell of -the innercasing. The complete inner casing is supported in the LP outer casing in a mannerpermitting free radial expansion, concentric with the shaft, and axial expansion from a

fixed point.


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LP TURBINEThe drum blading stages 1 to 3 of the double flow LP turbine are of thereaction type with 50 % reaction. They are located in the inner shell of theinner casing and thus form the front part of the LP blading.

All guide and moving blades have integral shrouds which, after insertion,provide continuous shrouding. The moving blades of the last stages are-twisted and have thinned tips. All guide and moving blades have T-roots.which also determine the distance between the blades. They are inserted intogrooves of corresponding design in the turbine shaft and inner casing andsecured by caulking material.

The last three stages of the LP turbine are designed as reaction stages.

The stationary blade rows are made into segments by welding the inner

rings, blades and outer rings together and bolting them to the inner casing.The blades of rows are made of steel sheet and are hollow. Drainage slotsare provided in the blades of row. Through these slots, any water on thesurface of the blades may be drawn away to the condenser.

The moving blades have curved fir-tree roots which are inserted in axial

grooves in the turbine shaft and :secured by means of caulking pieces.


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LP TURBINE

Shaft Seals : The function of the shaft seals, arranged between the bearing pedestals

and the LP turbine, is to seal the interior of the LP turbine casing against theatmosphere at the shaft penetrations.Sealing between the rotating and stationary elements of the turbine is achieved bymeans of seal strip caulked into seal rings. The pressure gradient across the seal isreduced by conversion of pressure energy into velocity energy which is thendissipated as turbulence as the steam passes through the numerous compartments.

Seal Rings: The seal rings are divided into several segments and mounted ingrooves in the shaft seal casing such that they are free to move radially. Eachsegment is held in position against a shoulder by 3 helical springs.Steam Spaces

Steam spaces are provided within the shaft seals. During start-up and on-line turbineoperation, seal steam is fed into space to prevent the penetration of air into thevacuum region of the system. The slight amounts of leakage steam which are still ableto pass the middle seal rings are conducted from the space into the seal steamcondenser.


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Rear Bearing Pedestal: The bearing pedestal is situated between the

LP turbine and generator. Its function is to bear the LP rotor.The bearing pedestal contains the following turbine components:

Journal bearingShaft vibration pick-up

Bearing pedestal vibration pick-up

LP TURBINE


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COUPLING & BARRING GEAR

There is limit to the length of turbine shaft that can be economically made.So there is need for coupling to join the individual rotors together to transmit the

driving torque to each other and generator rotor. Due to high torque flexiblecoupling can not be used ,otherwise thrust bearing is required for each looselyconnected shaft. So rigid coupling is used between turbine shafts so that entireshaft behaves as one continuous rotor.

Turning gear is provided to rotate turbine shafts slowly during the pre run up

operation and after shut down, to prevent uneven heating or cooling of shafts. Thatlead to bending between the fixed and moving with possible fouling between fixedand moving parts. Another advantage of turning gear is that the necessity forsuddenly admitting a large flow of steam, in order start turbine from rest is avoidedand therefore prevents sever temperature gradients occurring in turbine metal.

During turning gear operation, the shaft system is rotated by double row bladewheel which is driven by oil provided by AOP. This oil passes into nozzle box tonozzle which conduct the oil jet in front of the blading. After passing the bladingoil drains into bearing pedestal and flows with the bearing oil into return flowpiping.


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TURNING GEARA manual turning gear is provided in addition to hydraulic turning gear which

enables the combined shaft system to be rotated manually in the event of a

failure of normal hydraulic turning gear.

Steps to operate manual turning gear

1. Remove cover2. Then latch and attach a bar to lever

3. Barring lever will rotate the combined turbine shaft.


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TECHINICAL DATAThree cylinders reheat condensing turbine

Single flow HP turbine with 17 reaction stages Type: H30-100-2

Double-flow IP turbine with 12 reaction stages per flow Type:M30-63

Double-flow LP turbine with 6 reaction stages per flow Type: N30-2X10

2 main stop and control valves Type:EV320-1

2-reheat stop and control valves Type:IV560

1 swing check valve in cold reheats line DN-800 make BHEL Tiruchy

2 bypass stop and control valves DN-400

Extraction swing check valves: Extraction 1: No valve

Extraction 2 and 1 swing check valve without actuator 1 swing checkvalve with actuator

DN 800 make BHEL Tiruchy

Extraction 3: 1 swing check valve with actuator and 1 swing checkvalve without actuator

DN 500 make BHEL Tiruchy

Extraction 4.12 swing check valves with actuator DN 500 make BHEL Tiruchy

Extraction 4.2 2 swing check valves with actuator DN 500 make - BHEL Tiruchy

Extraction 5 1 swing check valve with actuator DN 400

and 1 swing check valve without actuator make BHEL Tiruchy

Extraction 6 no valve


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Speed

Rated speed 50.0 /s

Speed limitation in load and station auxiliaryload operation

Max. Speed, no time limitation 51.5 /s

Min. Speed, no time limitation 47.5 /s

Permissible for a maximum of 2 hours duringthe life of LP blading

Speed below 47.5 /s

Speed above 51.5 to 60 /s

Speed exclusion range at operation without

load

6.7 to 47.5/s

Standard over speed trip setting max. 55.5/s

This speed range should be passed through in one smooth operation to avoid endangering the blades due to resonanceSteam Pressures


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Steam Pressures

Rated Operation Long time Operation Short time

Initial Steam Bar 166.7 171.7 213.2

Before1 st HP drum stage 154.0 167.9 184.8 HP cylinder exhaust 44.1 51.1 56.5 * *

IP cylinder stop valve inlet 39.7 46.1 54.4 * *

Extraction 6 44.1 51.1 56.5

Extraction 5 17.3 22.4 22.4

Extraction 4 7.2 8.7 8.7

Extraction 3 2.56 3.23 3.23

Extraction 2 1.33 1.66 1.66

Extraction 1 0.256 0.41 0.41

LP cylinder exhaust 0.1013 0.3 0.3


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Low vacuum trip, standard setting

Hydraulic low vacuum trip 0.3 bar

Electrical low vacuum trip 0.3 bar

Hydraulic low vacuum trip bypass operation 0.6 bar

Seal Steam Supply System Pressure in seal steam header (aboveatmospheric)

35 mbar

Axial Shift

Alarm: 0.5 mm

Trip:

1 mm

Direction of rotation Anti clock wise when viewed from Front Pedestal towards the Generator


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Casing Temperatures

Wall TemperaturesAlarm at Machine must be shut

down at

HP turbine casingexhaust

480 500 C

Outer casing of LPcylinder 90

90 110 C

Permissible differential temperature between parallel steam supply lines:

No time limitation 17

CShort time period (1 5 min) 28 CIn the honest line the limitations indicated for initial steam and reheat temperature must not beexceeded.Spray water to LP turbine must be switched on at 90C.

Casing Temperatures

Temperature Difference Alarmat

Machine must be shutdown at

Difference between upper and lower casing halves HPturbine, middle

90 100 C

IP turbine, front 30 45 C

IP turbine, rear 30 45


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Motoring

Motoring is the condition in which the turbine is driven by the generator atrated speed with the stop and control valves closed, in this operating mode,certain turbine components are heated up by windage power in the blading.To prevent heat-up beyond permissible temperatures, motoring must not beallowed to continue for longer than one minute. If the condenser low vacuumlimit of 0.3 bars is exceeded, motoring must not be allowed to continue formore than 4 seconds.


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Bearing Metal Temperatures vibration weights

Bearing Temperatures Alarm at Machine must be shut down

at

Operation temperature below 756C

90 C 120 C

Operation temperature 75 to 85OC

100 C 120 C

Operation temperature 85 to 90OC

110 C 120 C

Operation temperature above 90OC

115 C 120 C Vibration

Absolute bearing housingvibration

Absolute Shaft Vibration

Standard alarm setting 30 M above normal level

Maximum alarm setting 35 m 120 m

Limit value for tripping 45 m 200 m

* The normal level is the reproducible vibration behaviour typical for the machine


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Weights

HP turbine, completely assembled94.6 T

IP turbine, top half outer casing 125.7 T

IP turbine, top half inner casing, complete with blading 15.5 T

LP turbine, top half outer casing complete 42.6 T

LP cylinder, top half outer shell of inner casing, complete with blading stationary blade carriers& diffuser

38.5 T

HP turbine rotor, complete with blading 16.3 T

IP turbine rotor, complete with blading 2 3.1 T

LP turbine rotor, complete with blading 85.8 T

Main stop and control valve, complete with Servo motors, without bend & pipe section 20.9 T

Reheat stop and control valve, complete servo motors, without bend & pipe section 32.2T

All weights have been calculated with safety


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Estimated oil requirements of bearings:

Bearing 1 (HP turbine, front pedestal)0.8 dM3/S

Bearing 2 15.4

Bearing 3 4.1 Bearing 4 8.6

Generator front bearing 7.92

Generator rear bearing 7.92

Exciter bearing 0.70

1 Duplex Oil filter for bearing oil (Full Flow) 150 mm

Duplex oil filter, Type - 2.68.2, Size 355/750, Make Boll & Kirch Filtration particle size of Duplex filter element 37 micro M

Filtration particle size of main oil tank filter element 250 micro M

Safety valve in jacking oil system, setting

Max 200 bar

Pressure limiting valve in jacking oil system, setting 180 bar

1 Duplex Oil Filter for Jacking Oil 25 mm

Filtration Particle size of Jacking Oil Filter

37 micro M


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Jacking oil pump, cut-in and out speeds

Jacking oil pump must be in operation at turbine speeds below approx. 51 0 rpm to avoid damageto bearings.

Jacking oil pump should be cut out at speeds above approx. 540 rpm

Oil PUMPS

Main Oilpump

Auxiliaryoil pump

DC EmergencyOil pump

Jacking oilpump

Quantity 1 2 1 AC-2

DC-1

Maker BHEL KSB KSB Tushako

Type 97.22dm3/s

ETA- 1 50-50VL

ETA-100-33VLSDF80

Sdf80

Capacity(rated)

75 dm3/s 89.25 30 dm3/s 1.53 dm3/s

Dischargepressure

8.6 Bar 6.2 Bar 2.3 178 bar

Speed 50 24.75 24.3 49.42 /S

Drive Turbine AC Motor DC Motor ACMotor

DC Motor


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Steam Purity Required values for main steam condensateThe deposits which occur in turbines due to impurities in the steam can lead to thermodynamicand mechanical inefficiencies and, with the presence of salts, especially chlorides, and sodiumhydroxide also cause damage to turbine parts. The corrosion stressing caused by active

deposits, f or example, has an adverse effect on the fatigue strength of the blade material whenthe steam is in the transition zone between the superheated and the saturated state.Compliance with the target values is mandatory in continuous operation, with the values in thenormal operation column preferable. With the commissioning of a new plant and starting-upoperation, however, these values ran not be attained with an economical outlay. The valueslisted in the column "starting-up operation" are then valid.It should be pointed out that adherence to the target values does not rule out deposition in theturbine with absolute certainty. Wherever possible every effort should be made to achieve thevalues in the normal operation column.A recording instrument may be used to continuously monitor the electrical conductivity of themain steam and turbine condensate following a strongly acid cation exchange unit. In order todetermine slight impurities, the sodium concentration should be measured in addition to this.Should saline contamination occur, the turbine is to be immediately washed with saturatedsteam to remove salt deposits.Whether an alkaline, neutral or combined method is used for conditioning, the water-steamcirculation is for the customer to decide. If an alkaline method is used, the oxygen content inthe main steam condensate can be max. 0.02 mg/kg and the pH value in the turbinecondensate max. 9.3 with brass condenser piping. When the condenser piping is of cooper-nickel alloys, the pH value must not exceed 9.5. There is no limitation f or the pH value withnon-corroding steel or titanium .


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QUANTITYTARGET VALUENORMAL OPERATION START UP Conductivity at2,5'C, down stream of highly acidic sampling cation exchanger, continuousmeasurement. at sampling pointS/cm< 0.20.1

Presentation Main Turbine

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