Pre commissioning steam turbines load trial

BY:NAGESH H

PRE COMMISSIONING : The activities carried out before passing steam to the turbine is called pre commissioning.

COMMISSIONING: The activities carried out to ensure turbine performance is as per design is known as commissioning.

TECHNICAL DATA

SUBBURAJ PAPER PVT LTD

PRE COMMISSIONING

STEAM BLOWINGCONDENSER TESTBEARING CLEARANCE, FLOAT, DUMP OF ROTOR,GEAR

AND PINIONTHROTTLE VALVE SETTINGALL SAFETY TRIP FUNCTIONING AND RESPONSE OF SEV

STEAM BLOWINGThe purpose of blowing the steam lines prior to starting

up a new unit is to remove any foreign particle remaining in steam inlet pipeline.

The principle behind steam blowing is thermal cycling i.e heating of pipe lines by blowing steam & cooling. This will tend to break mill scale / weld slag away from the pipe wall due to difference in co-efficient of thermal expansion.

EQUIPMENTSTemporary pipingTemporary piping supportSilencerTarget plate

PROCEDURE FOR STEAM BLOWING….1. Disconnect steam inlet pipe

from turbine emergency stop valve

2. Arrange for target plate of mirror finished aluminum of thickness 10 to 12 mm to be fitted at 1 meter away in the temporary blowing line. which is placed in the main steam line by making a fixture

3. During the blowing down process open all the drain lines from boiler to inlet pipe flange

4. Steam blows should be carried out by fully opening the isolating valve.

SUPPORTING PLATE

STEAM INLET

TARGET PLATE

PROCEDURE FOR STEAM BLOWING5. Bring the boiler press. up to 70 to 80% of

working press. & temp., blow down the steam line until press. drops to 20 to 30% of working press./temp. recommended by boiler manufacturer and then allow the line to get cooled(~40°C ) and then hammer the steam pipe line near joints .

6. Repeat this procedure for three times.7. Now place the target plate in the fixture

& blow down the steam line and allow it to cool.

8. This cycle is repeated till we get acceptance value , In each cycle continue hammering and Stamp the cycle no. on the receiving face of the target plate.

Indentation is acceptable when there are no more than 2 dents of 0.2mm in a 50X50 mm section of target plate.

ACCEPTANCE CRITERIA

PRECAUTIONS1. Check that all pipes are supported properly during blow down.2. Necessary safety precautions must be taken such as fencing of the area

and providing ear protection against the inevitable noise generated during blow down process.

3. No one should move around the blowing area

CONDENSER MASS FLUSHINGDummy flange

•Objective: To clean the cooling water inlet and outlet pipe lines of condenser from cooling pond to cooling tower.

•Procedure:• Place the dummy flanges in cooling water inlet and outlet line of the condenser.•Prepare a temporary pipe line for flushing•Pump the water from cooling pond till water flows out on top of cooling tower and then switch off the pump.•Drain the water .•Repeat this procedure until the water is clean.

Dummy flange

To cooling tower at 12 m height

Chemically treated water from cooling pond

2 to 2.5 kg/sq .cm

Drain

condenser

CONDENSER TESTS1.WATER LEAK TEST:

•Pipe line is made from DM water pump to condenser shell.

•Fill the condenser with DM water up to the bottom of exhaust casing until water leaks from the exhaust thermo well of turbine.

•Ensure that all the pipe lines are filled with water which are connected in the vacuum system.

•Hold the water up to one hr and observe any leakage from the flange and welded joints.

• Ensure that there is no leakage in the system

•Drain the water completely from the system after the completion of test

EXHAUST STEAM

COOLING WATER INLET

COOLING WATER OUTLET

HOTWELL

CONDENSER TESTS

2. VACUUM DROP TEST

•Isolate the turbine from condenser by providing a ms plate of approximate 10 to 15 mm thickness between condenser flange and bellow flange provided at turbine exhaust flange along with turbine .

•Fill the condenser hot well to normal level

•Start hogger ejector and create vacuum to the designed value of 0.1 ATA and close the hogger ejector

•Check the rate of vacuum drop

•Drop in vacuum should not exceed 0.01 kg/sq.cm in 30 minutes.

EXHAUST STEAM

COOLING WATER INLET

COOLING WATER OUTLET

HOTWELL

•Place the bottom bearing shells and load the rotor on bearings.•Place a lead wire of 0.7mm thick with a coat of grease circumferentially around the top half of the journal.•Place the top half of bearing shell with its bearing cap and tighten it.•Remove the crushed lead wire and measure the thickness of the crushed lead wire which gives the existing bearing diametrical clearance

BEARING CLEARENCE

DESCRIPTION OBSERVED(mm) REQUIRED(mm)

Rotor fore 0.21 0.18-0.23

Rotor after 0.21 0.22-0.26

Pinion fore 0.37 0.37-0.42

Pinion after 0.37 0.37-0.42

Gear fore 0.27 0.25-0.30

Gear after 0.26 0.25-0.30

Dump check is done to ensure minimum clearance b/w rotor & nozzle chest and diaphragm nozzle.

Place the rotor on journal bearing. Assemble the top bearing shells

into the bottom bearings and place the bearing cap.

Insert the active thrust pad into its position.

Description (Dump) Observed Required

Rotor 0.72 0.7-0.8

Gear 0.65 0.40-0.75

Dial indicator position

To check the float of the rotor ,the same procedure has to be followed but the rotor movement is restricted by using non active thrust pad.

Description Observed Required

Rotor 0.35 0.30-035

THROTTLE VALVE LIFT

First valve is adjusted by feeler gauge and other two valves are set by vernier caliper

MAX.LIFT

PRESSURE SETTING

Control oil pressure 14kg/sq.cm

Bearing oil pressure 1.9 kg/sq.cm

Accumulator pre-charge pressure 12kg/sq.cm

(80% of control oil pressure)

Trip circuit oil pressure 1.5 kg/sq.cm

VERIFY ALL INTERLOCKS AND ALARMS

MANUAL TRIP

L P TRIP

SOLENOID TRIP

CHECK ALL SAFETY TRIPS

ITEM SETTING VALUE

SET VALUE

LP TRIPTRIP PR.RESET PR.

0.5-0.8

0.8-1.2 0.80.9

SOLENOID TRIP

0.5 0.5

ENSURE THAT SEV AND TV CLOSES IN ALL TRIPPINGOVER SPEED

TRIP

VIBRATION PROBE SETTING

PROBES HAS TO BE SET FOR 9 to 12VOLTS

1.TURBINE FORE 7.ALTERATOR FORE2.TURBINE AFTER 8.ALTERNATOR AFTER3.PINION FORE 9.AXIAL 4.PINION AFTER5.GEAR FORE6.GEAR AFTER

9

To check various pressure settings with in the lube oil and control oil system

To check vibration level with in limitsGovernor take overTo check the over speed trip and electrical trips are functioning correctlyTo prove performance of machine and to satisfy customer

COMMISSIONING AND LOAD TRIAL

OBJECTIVES:

COMMISSIONING PROCEDURE FOR SOLO RUN TEST AND LOAD RUN TEST

• Open all drains of steam in turbine

•SEV drain

•Nozzle chest drain

•Wheel case drain

•Casing drain

•Throttle valve drain

•Check oil level in oil tank through oil level gauge and temperature of the oil should be minimum 35deg c

• Ensure that cooling water to oil cooler, condenser,GVC is flowing

• Start AOP

•Start the motor driven barring gear. An interlock ensures that the baring gear can not be started before bearing oil pressure is established i.e 1.5kg/sq.cm

• Run barring gear for a period of 12 hours, if turbine is started first time for an SCG 3 turbine.

•Check the vibration level are with in limits•Allow sealing steam for laby packing's

START EJECTOR SYSTEM

HOGGER

COOLING WATER INLET AND OUTLET

MOTIVE STEAM

VAPOUR FROM CONDENSER

BASIC PRINCIPLE

Entrapped gases

MOTIVE STEAM

START MOTOR DRIVEN CEP

BLO

DISCHARGE

SUCTION

DELIVERY

To ejector tubes

Suction from hot well

Balancing leak off

P=6kg/cm sq

• RESET ALL SAFETY TRIPS

Solenoid trip

Manual trip

LP trip

MANUAL TRIP

L P TRIP

SOLENOID TRIP

CONTROL OIL LINES

DRAIN LINE

PUSH TO TRIP

PULL TO RESET

•Crack open the steam supply isolating valve and warm up the steam pipe line to turbine SEV

•Reasons for warm up :

To avoid uneven expansion of pipe line, rotor and casing

To avoid water hammering effect

•Start GVC blower

•Initially lift the HP actuator lever

•Gradually open the SEV, which should be sufficient for warming nozzles and casing.

•After few minutes, when the turbine warmed through and all water has been expelled, then partially close the turbine drains

TURBINE START UP CURVE TO BE FOLLOWED

1st cs-2600 rpm

Sudden jump 2300-2900

• CHECK FOR OVER SPEED TRIP AND SET ELECTRICAL TRIPSET OVER SPEED TRIP WITH IN THE RANGE OF 110-115% OF RATED SPEED 7829rpm

TO INCREASE TRIP SPEED

Valve

Remove material on this opposite face if os trip is less

TURBINE START UP CURVE TO BE FOLLOWED

TURBINE START UP CURVE TO BE FOLLOWED

CHECK FOR VIBRATION LEVELS AND TEMPARATURE

ITEM POSITION READINGS

MILS/PP

ROTOR FORE BRG

X

Y

0.8

0.7

ROTOR AFTER BRG

X

Y

0.73

0.42

PINION FORE BRG

X

Y

1.75

1.48

PINION AFTER BRG

X

Y

0.74

0.46

GEAR FORE BRG

X

Y

0.25

0.27

GEAR AFTER

BRG

X

Y

0.33

0.42

AXIAL X (TOP)

Y (BOTTOM)

5.3

4.2

VIBRATION READINGS IN SOLO RUN TEST

LOAD CURVE DURING STABLE OPERATION

ITEM POSITION READINGSMILS/PP

ROTOR FORE BRG X

Y

0.8

0.64

ROTOR AFTER BRG

X

Y

0.51

0.4

PINION FORE BRG X

Y

1.8

1.5

PINION AFTER BRG

X

Y

0.68

0.43

GEAR FORE BRG X

Y

0.28

0.38

GEAR AFTER BRG X

Y

0.37

0.58

AXIAL X

Y

5.3

4

DRIVEN MACHINE FORE BRG

X

Y

0.9

1.63

DRIVEN MACHINE AFTER BRG

X

Y

0.69

0.55

VIBRATION READINGS WITH LOAD RUN TEST

SPEED RPM 6822

LOAD MW 1.5

STEAM INLET PRESSURE kg/Sq.cm 33.8436TEMP. °C

STEAM FLOW TPH 14.3

WHEEL CASE PR. kg/Sq.cm 4

EXTRACTION PR. kg/Sq.cm 0.75TEMP °C 203FLOW TPH 3.3

EXHAUST PRESSURE PRE. kg/Sq.cm -0.83TEMP °C 84

HOT WELL TEMP °C 45

COOLING WATER

INLET PR kg/Sq.cm 1.6INLET TEMP °C 19OUT LET PR. kg/Sq.cm 1.3OUT LET TEMP °C 28

EJECTOR STEAM INLET PR. kg/Sq.cm 10INLET TEMP °C 330VACCUM PR. kg/Sq.cm -0.85

OIL PRESSURE LUBE OIL kg/Sq.cm 2.1CONTROL OIL kg/Sq.cm 14D.P ACROSS FILTER kg/Sq.cm 0.1

BRG TEMP. °C ROTOR FORE 65.8AFTER 82.1

PINION FORE 69.1AFTER 56.6

GEAR FORE 51.2AFTER 46.2

ALTERNATER DE 65NDE 67

COOLER OIL TEMP. INLET °C 45OUT LET °C 32

LOAD TRIAL(PARAMETERS)

COMPARISION OF SPECIFIC STEAM CONSUMPTION

OF MACHINE AT SITE WITH RESPECT TO PERFORMANCE CURVE

STEAM CONSUMPTION*CORRECTION FACTORS(A,B,C,D)*AGE FACTOR

POWER GENERATIONSSC =

SSC = Kg/kwh

SL NO

PARAMETERS PROJECTED VALUES

AVERAGE VALUE

UNITS

A Inlet steam pressure.

Kg/sq.Cm

B Inlet steam temperature

° C

C Exhaust steam pressure

Kg/sq.Cm

D Turbine speed RpmE Electrical load Mw

ACTUAL STEAM CONSUMPTION

F Total power consumption Kwh

G Total steam consumption Kg

Inlet steam pressure

Inlet steam temperature

Exhaust steam pressure

Turbine speed

Age factor

Correction factors

STEAM CONSUMPTION*CORRECTION FACTORS(A,B,C,D)*AGE FACTOR

POWER GENERATIONSSC =

ACTUAL SSC = 5.73 kg/kWH at average load of 12.5 mw

Sl no

parameters Projected values

Average value

units

A Inlet steam pressure. 66 57 Kg/sq.Cm

B Inlet steam temperature 490 502 Degc

C Exhaust steam pressure 1.54 0.8 Kg/sq.Cm

D Turbine speed 7055 6693 Rpm

E Electrical load 15 12.5 Mw

ACTUAL STEAM CONSUMPTION

F Total power consumption 25000 Kwh

G Total steam consumption 165000 Kg

Inlet steam pressure

0.9

Inlet steam temperature

1.0

Exhaust steam pressure

1.0

Turbine speed 0.965

Age factor 1.0

Correction factors

PROJECTED SSC = 6.17 kg/kWH at average load of 12.5 mw

Example: FR 1

PROBLEM FACED IN SITE

SITE:SUBBURAJ PAPERS

•Dump was found 0.37 instead of 0.75Cause: High points in the nozzle chest seam welding. Corrective action: The seam welding in the nozzle chest was blue matched with the shrouding of moving blade and some high point was found in welding. welding high points were corrected by filing and finally dump was achieved.

•CEP was consuming more than rated currentCause: Misalignment of pump and motor