Power Plant Operation

IG/05 (Restricted (Restricted Circulation Circulation Only)

POWER PLANT OPERATION

Power Management Institute NOIDA

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CONTENTS

S.No.

Description

Page Nos.

1.

Boiler Auxiliaries (210 MW)

1

2.

Boiler

9

3.

Turbine Auxiliaries

46

4.

Turbine

57

5.

Generator Auxiliaries (210 MW)

91

6.

Generator

97

7.

General Operating Instructions

119

8.

500 MW Operations

136

9.

10.

General Guidelines for Unit Load Changes and Hot Restart

500 MW Turbine Operation (KWU)

147

157













































1.

Boi Boi l er Auxil uxi uxil i arie ri ess (21 (210 MW M M W)

1

MILLING SYSTEM

1.1

Most efficient way of utilising coal for steam generation is to burn it in pulverised form. The coal is pulverised to a fineness such that 70-80% passes through a 200 Mesh sieve. Normally low speed ball mills or medium speed vertical spindle mills are employed in power station for this purpose. The factors that affect the operation of the mill (whereby reducing the output) are as follows:

1.1.1

Grindability of coal: If harder coal is fed to the mill (i.e. coal having lower hardgrove index) then mill output gets reduced and vice versa.

1.1.2

Moisture content of coal: More the moisture content in coal, due to limitation in drying capacity lesser will be the mill output & vice versa.

1.1.3

Fineness of output: If output desired is of more fineness then there is corresponding capacity reduction of mill.

1.1.4

Size of coal input: If the raw coal size fed to the mill is of larger size then mill output will reduce.

1. 1.5

Mill wear: More wear and tear of grinding elements reduce the output from mill.

1.2

The trend normally, these days, is to use medium speed vertical spindle mills with pressurised system. The typical checks for starting a milling system are













































2.

PRE START CHECKS (Typical: Raymond Bowl Mill)

2.1

Local: (to be made by local operator)

2.1.1

-

Ensure R.C. Bunker level satisfactory.

2.1.2

-

R.C.

feeder and mill properly boxed up and no maintenance staff

working.

2.1.3 2.1. 3

-

Gear box oil level normal.

2.1.4

-

Lub. oil coolers charged.

2.1.5

-

Tramp iron gate open.

2.1.6

-

Cold air gate open. Hot air gate closed.

2.1.7

-

Mill outlet valve open

2.1.8

-

2.1.9

-

2.2

Take Tak e out out emergency push button and give clearance to UCB for

Seal air valve open.

Mill fire fighting system ready.

starting.

2.3

U.C.B.: U.C. B.: (to be made by desk operator)

2.3.1 2.3. 1

-

Ensure no PTW pending.

2.3.2

-

Ensure at least one P.A. fan and a seal air fan is in service. Check the header pressure for both primary and seal air is normal.













































2.3.4

-

Check that mill start permissives as per FSSS are satisfied (for the help of operator these permissives are written on FSSS panel and when the condition is satisfied it is indicated by a glowing bulb).

2.3.5

-

Ensure E.P. zones have been charged (for first mill) .

2.3.6

-

Ensure attemperation valves are ready for operation.

2.3.7

-

Inform turbine operator of mill start up.

2.3.8

-

Get Get the electrical supply for the mill.

2.3.9

-

Inform the local operator to be near mill for start up.

2.4

Start the mill

3.

POST START CHECKS

3.1

Local

3.1.1 3.1. 1

-

Check no abnormal sound from mill.

3.1.2

-

Check return oil flow fl ow from upper bearing is satisfactory. satisfacto ry.

3.1.3

-

Check all the rollers are rotating and the rate of reject is normal (after the mill is loaded).

3.2 3.2.1

3.2.2

U.C.B. -

-

Check mill starting time and current. Ensure that they are normal.

Open hot air gate.













































3.2.4

-

Start the RC feeder and load the mill gradually

3.2.5

-

Keep the air flow through mill - 54 T/hr .

3.2.6

-

Keep watch watch on mill differential to avoid mill choking.

3.2.7

-

Maintain mill outlet temperature between 75°C to 80°C.

3.3

-

As the pressure, temperature of main steam shoots up with coal firing proper check should be kept on these parameters. (Especially for first mill).

DRAFT SYSTEM 4.

FAN OPERATION

4.1 4.1

The Operation of fan depends on the type of fan to be started but there are several common prestart checks.

4.2

For large units, the fan start up is invariably sequence controlled, wh ich means that once the button is pressed, an automatic checking system ensures that all systems associated with the fan are in good working order. Nevertheless a considerable number of 'on line' interlocks must be satisfied before the main motor is energised. (Refer fig.1 for typical fan operation).

4.3

The common prestart checks which are essential are as follows:

5.

LOCAL CHECKS (to be made by local operator)

5.1

Generally Generally inspect the fan. Ensure no maintenance staff working and all manholes etc. closed. closed.















































5. 3

Check Regulating vanes minimum.

5.4

Ensure lub oil tank level is normal. Start lub oil pump. Check auto operation of standby pump. Check lub oil pressure, flow and temperature. Charge lub oil coolers.

5.5

Check control oil pressure, adjust if necessary. (for reaction fans).

5.6

Charge motor cooler from water side (if provided).

5.7

Check fan/fan motor bearing temperatures are normal.

5.8

Take out emergency push button and given clearance to UCB for starting the fan.

6.

CHECKS IN UCB : (By desk Operator)

6.1

Ensure no PTW pending.

6.2

Line up the flue gas path.

6.3

Ensure discharge damper closed, regulating vanes minimum, lub-oil pressure O.K. (UCB indications).

6.4

Ensure interlocked auxiliary is in service

























































































6.9

Ask the local operator to be at site and inform him when the fan is to be actually started.

6.10

Start Start fan. fan. Not e down starting current and time.

6.11

Check that fan discharge damper opens on interlock after preset time delay. Check the operation o peration of o f interconnecting interconn ecting dampers. damp ers. (If dampers provided provide d are manual then the discharge damper is to be opened and interconnecting dampers to be closed manually).

6.12

Check locally for bearing vibrations, abnormal sounds etc., they should be within normal limits.

6.13

The above checks can only be regarded as examples, as fan operation vary from station to station and the correct operating procedure as suggested by Manufacturer must be followed.

6.14

It is important to note that the fans take heavy starting current and long starting times. So always allow the fan amperage to fall to minimum value before starting the next fan. Starting fans in rapid succession can result in transformer overload. o verload.

7. 7.1

ELECTROSTATIC PRECIPITATORS The boiler pressure will be raised initially on oil burners, as P.F. mills can not













































7.2.1

If EP bypasses are not fitted, the gas flow should be limited to one of the main passes during the initial oil firing stage of the pressure raising. The other passes should be kept isolated during this period. In this way we can ensure that at least remaining passes are not affected by oil vapour. But the E.P. rapping mechanism shall be put in service prior to commencement of oil firing. Anti-condensation heaters of the insulators be taken into service well before boiler light up is initiated. Also it is observed that main cause of poor E.P. performance is high hopper level and this thi s condition is aggravated aggrav ated by moisture when a cold boiler is being lighted up. The hopper heaters, if provided must also be taken in service. Sometimes the hoppers on modern plant are lined up with smooth materials such as fibre glass and ceramics to facilitate the flow. The practice of 'thumping' the hoppers with rods or bars to get the dust flowing should be discouraged as it can damage these linings.

7.3

The EP zones must be taken into service just before coal firing is started in the boiler. boi ler. The The frequency of rapping should sho uld be properly adjusted and a nd their operation must be locally checked.













































2.

Boiler Boiler

A.

PRE-START CHECKS, START-UP & LOADING

1.

PrePre- Start Checks

1.1

Check that all maintenance permits concerning the boiler pressure parts, flue gas and air side paths are cancelled.

1.2

Check that all the manholes, inspection doors of furnace, flue gas and air path, drum, deaerator, fuel storage tank, C.B.D. tank, I.B.D. tank, fans, mills etc. are tight closed,

1.3

Check that:

1.3.1

Reserve Power and D.C. control system supply is established to 6.6 KV station buses and unit auxiliary buses; 415 volts supply to station service switch gears, unit service switchgear, E.P. switch gear, off-site plant switch gears. Boiler M.C.C., compressor M.C.C., Miscellaneous service M.C.C., soot blower M.C.C., V.D.D.C., F.S.S.S. panels etc.

1.3.2

220 V.D.C. board, 220 volts DC supply to control panels relay panels, emergency lighting, FSSS etc. is established.

1.3.3

110 V.A.C. supply to FSSS panels is established. establishe d.















































1.7

Check Check that station air compressors are in service and air supply is established to Boiler and auxiliaries area and Air heaters air motors.

1.8

Check that clarified water pump (s) is/are in service and clarified water supply for cooling is available for all Boiler auxiliaries.

1.8.1

Check that clarified water booster pump is in service and cooling water supply to sample coolers, air heater lub. oil coolers is available.

1.9

Check that Hydrazine dosing and Phosphate dosing system are ready for taking in service.

1.10

Check that adequate D.M. water is stored in D.M. water tanks.

1.11

Check that Auxiliary steam supply header is charged through interconnection from running Units. (Care should be taken to inform adjacent unit from which steam is being taken prior to charging the header)













































1.18

Check that Boiler Drum level gauge glasses and remote drum level indicators indicator s are in service.

1.19

Check that furnace temperature probe is available.

1.20

Check that all the controls and interlock circuits have been checked and are ready for operation. Check that all protection circuits have been checked and are OK.

1.21

Check that bottom ash hopper and seal trough have been filled and constant over flow is maintained.

1.22

Check that all fly ash hoppers have been evacuated and ash handling water supply is established to all the fly ash hoppers.

1.23

Check that E.I.Ps have been cleaned and are ready for operat ion.

1.24

Check that coal bunker filling has started.













































2.3

B.F.P. on Recirculation.

2.4

Boiler air & flue gas system is lined up and start A.P.H.'s. Both the Air heaters should be taken into service if available.

2.5

Take lube oil system of I.D. Fans in service and take oil systems of F.D. fans in service.

2.6

Start one I.D. fan and start one F.D. fan. Start second set of fans if available. avail able. (follow the fan start-up procedure as explained earlier).

2.7

Maintain 30% Air flow and -5 to -10mm WCL furnace draft. Airflow shall not be more than 40%.

2.8

Put secondary air damper control system on "Auto" & check that auxiliary air dampers are modulating to maintain 35-40 mm WC Windbox to furnace differential pressure, check fuel air dampers are modulating with aux. air dampers.













































ix)

All the the warm warm up and heavy oil nozzle valves at all elevations are proven closed.

x)

All auxiliary air dampers modulating

to maintain

adequate

wind

box to furnace differential pressure.

2.13

xi)

All purvarizers purvarizer s are off.

xii)

All feeders are off.

xiii)

All hot air shut off gates are fully closed.

xiv)

All cold air dampers are less than 5% Open.

xv)

All elevation flame scanners show NO FLAME,

xvi)

No boiler trip command is present.

Check that atomising air lines for igniters & W.U. oil guns are lined up & charged and make ready each W.U. oil corner individually.

2.14

Start furnace purge by pressing start purge push button at F.S.S.S. console and after 5 minutes check that purge complete light comes on.

2.14.1

Open superheater start up vents vents and superheate super heaterr drains. drain s.







































































































































2.17

Start AB elevation elevation one pair of L.O. guns by depressing pair start P.B. on FSSS insert console, check associated AB elevation at least 3 out of 4 igniters are proven on, check that selected pair of L.O. guns are proven on in time sequence and maintain warm up oil pressure, through pressure regulating valve.

2.18

Start second pair of L.O. guns A.B. elevation by depressing depressin g start PB or FSSS console, maintain warm up pressure through regulating valve and check that at least 3 out of 4 L.O. guns are proven on in timed sequence.

2.19

Control firing rate during initial warming up such that boiler starts steaming













































3.

Boiler Loading

3.1

Boiler lighted up & main steam pressure pressure & temperatur temperatures es are 5 Kg/cm &

2

190°C.

3.2

Prepare for Heavy oil firing.

3.3

Check auxiliary steam header is charged through interconnection interconn ection and check auxiliary steam line F.O. heaters & tracing steam lines are charged.

3.4

Check H.O. system is in service on recirculation before H.O. pressure heaters

























































































3.12

Take H.P. and L.P. bypass system in service when Condenser vacuum = 540mm Hg. Main Mai n Steam Pr=6 ATA, M.S.Temp.=22 M.S.Tem p.=225°C, 5°C, ensure B.F.P. and condensate condensate pumps are in service.

3.13

Close start-up vent valves and when flow is established through bypass system give clearance to start turbine rolling.

3.14

Throttle Main Steam line drain valves, take drum level protection in service. Warm-up M.S. lines, C.R.H., H.R.H. line & transfer lines. Check M.S. 2

Parameters of E.S.V. are 12-14 Kg/cm (g) and 240-260°C. Check M.S. Pipe metal temp. is above 150°C and C.R. pipe metal above 100°C. H.P. transfer















































3.22

Prepare for coal firing, start one PA Fan and charge electrostatic precipitators fields.

3.23

Make S.H. spray control system ready and make R.H. spray control system















































3.32

Increase the feeder speed. Equalise the loading on both the feeders, boiler 2

parameters: M.S. Pressure = 82Kg/cm M.S. M.S. Temp = 475°C 4 75°C Load = 60MW.

3.33

When load on unit is 70MW check H.P. heaters are taken in service. M.S.





























































































3.43

Increase load on the generator and simultaneously increase Boiler firing rate 2

and boiler pressure 120 Kg/cm M.S. Temp 530°C Load 120MW, put M.S. & R.H. Steam temp, control system on Auto.















































B. 1.

NORMAL SHUT DOWN TO COLD Suitable for shut downs of medium duration when Boiler or Turbine inspection is planned when Unit is operating at 210 MW with combustion control, fuel











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































4.

ENSURE GENERATOR SEAL OIL & HYDROGEN COOLING SYSTEM ARE NORMAL

4.1

Ensure the Main oil tank level is normal and quality of oil to be O.K.

4.2

A.C. seal oil pump should be running and Check the availability availabili ty of D.C. seal oil pump.

4.3

Hydrogen pressure in Generator casing should be maintained at rated value and seal oil system and H2 cooling system running normal.

4.4

A.C. standby oil pump should be running. Lub. oil pressure at rated value at bearing header and also check the availability of D.C. oil pump.

4.5

Lube oil pump interlock switch should be 'ON' and oil temperature at bearing seal should be around 40°C.

4.6

Check protection and interlock of lub. oil system.

5.

ENSURE TURBINE ROTOR IS ON BARRING GEAR

5.1

Check the protection of Barring gear (barring gear should not start when lub. 2

oil pressure rails below 0.3 Kg/cm ) .

5.2

Ensure that turbine rotor is at stand still position and lub oil system running start the Barring gear motor.

5.3

Note down the amp. of the motor and check Barring gear protection and again restart Barring gear.

5.4

Keep a constant constant watch on lub. oil pressure and temp.

6.

ENSURE AUXILIARY AUXILIAR Y STEAM LINE IS CHARGED CHARG ED













































6.2

Keep Kee p the he drain valve near the Gland steam Cooler open and charge the steam line for ejector, gland steam cooler and steam seals by opening the valve.

6.3

After the line is heated up (for 15 minutes to 20 minutes) throttle the drain valve near Gland G land Steam cooler to avoid wastage of steam.

7.

VACUUM PULLING

7.1

Ensure CW pumps are in service

7.2

Ensure condensate system in service, Main ejectors, (both) L.P. heaters (all) are charged from water side, all valves subjected to vacuum should be sealed by condensate water.

7.3

Ensure that turbine is on Barring gear.

7.4

Ensure that Auxiliary steam is charged from 16 at header to turbine seal and ejector header.

7.5

Close the vacuum breaker valves near main ejector and fill the funnel with DM water for sealing.

7.6

Prior to charging the starting ejector. Open the drain valve at the isolating valve of steam line.

7.7

Start GSC ejector and admit steam to seals.

7.8

Open the drain valves the condenser from the first stage of the ejector.

7.9

Open the steam to ejector, through isolating valves when vacuum in condenser is 400 mm of Hg. and see the steam pressure to main ejector of rated value and see that vacuum is steadily rising in the condenser and stop













































B.

STARTING OF TURBINE FROM COLD STATE

1.

PRESTART OPERATION

1.1

Check that all prestart requirements are over.

1.2

Before HP/LP bypass stations are brought into operation check:

1.2.1

ESV, IV are closed.

1.2.2

Oil system of the bypass station is put into operation by switching on its motor.

1.2.3

Vacuum in the condenser is at rated roughly 600 mm of Hg.

1.2.4

Condensate Condensate flow to steam throw off devices in the condenser are established by opening of the valves.

1.3

Ensure that the valves of the bypass system are fully closed by reading the respective position indicators.

1.4

Set the temperature set point of HP bypass station at rated value with the help of push button.

1.5

Put the pressure controllers and slave positions of each HP bypass valves on manual mode with the help of push button.

1.6

Put the LP bypass valves ‘Auto’ ‘Auto’ mode and set the temperature set point of LP bypass station at rated value roughly 200°C with the help of push button by reading its value on the indicator.

1.7

Put the control of LP bypass valves on 'auto' mode with pressure loop in circuit with the help of selector switch by making the contact in 'R position and













































1.8

Check that the HPT evacuating valves and bypass valves across NRV cold reheat line are tightly closed.

1.9

After the internal superheater flow has been established through start up vent, open the drain valves before bypass and after bypass drain valves, open the drain valves of MS, CR & HR lines and also open after LP bypass drain valves.

1.10

Open fully the HP bypass bypass with the help of push button and then open the boiler outlet valves and check the temperature control loop is functioning normal.

1.11

Watch the rise of metal temperature of MS, CR & HR lines and after 50°C superheat is available at the superheater outlet open the bypass valves of MSV for heating the pipe lines upto turbine.

1.12

Open the ESV to CVS drain valves and Open ESV by about 10-20 mm as per the scale according to instruction and heat the steam admission pipe upto control valves to a temp. of 150°C as rated and rise of metal temp. should not be more than 4°C per minute.

1.13

Open the bypass valves across the NRVs in the cold reheat line and the Drain valves of HPT and heat the HP turbine upto 150°C.

1.14

2

Check the steam pressure in hot reheat line to be less than 1 Kg/cm (gauge) before starting the heating of steam admission pipe upto control valves of IPT and if the pressure exceeds limiting value adjust the set value at 1 Kg/cm 2 (gauge) with the help of push button and indicator of LP bypass station.

1.15

Open the IV to CVs drain valves and open the interceptor valve servomotor by about 10-15 mm as per the scale instructions and heat the steam admission pipes upto control valves to a specified temp, roughly 100°C.













































1.17

Close ESV & IV and bring the control of LP bypass valves on ‘Manual' mode with the help of push button.

1.18

Manually close the HP bypass valves with the help of push button and when the pressure in the reheat line comes to condenser pressure manually close the LP bypass with the help of push button.

1.19

After having accomplished the heating, check and note down the following readings in the log sheet before rolling the turbine.

1.19.1

Metal temp. of pipes before MSV, and also before ESV, while heating the main steam and reheat steam pipes, the difference in temperature of pipes should not exceed 15°C. But when the turbine is on load, this difference should not be more than 10°C.

1.19.2

Metal temp. of steam admission lines.

1.19.3

Metal temp. of hot reheat line. line .

1.19.4

Metal temp. of interceptor valve.

1.19.5

Metal temp. of HPT and IPT top/bottom.

1.19.6

Steam parameter before MSV.

1.19.7

Differential expansion of HP rotor, IP rotor and LP rotor.

1.19.8

Axial, shift, total expansion of HPT/IPT and condenser vacuum.

1.19.9

Eccentricity of turbine rotor on barring gear.

1.20

Open the drain valves of 'HPT, IPT, HP and LP extraction valves and open ESV, IV, control valves of HPT and IPT. completely with the help of control















































2.

RULLING INSTRUCTIONS INSTRU CTIONS

2.1

Slowly open the bypass valves of main steam valve before ESV.

2.2

Allow the steam to roll the turbine and check check during the process of raising the speed bearing vibration should not exceed 40 microns.

2.3

Check that barring gear has got disengaged and its motor gets switched off automatically.

2.4

At a speed of 500 rpm, stop the steam supply to the turbine by closing the bybypass valves of MSV and listen carefully for any rubbing sound. If any abnormality is found stop the rolling of the turbine.

2.5

If the turbine is in healthy state, again raise the speed to 500 rpm by opening the bypass valves of MS valve and soak the set for 5-10 5-10 mts.

2.6

It is prohibited prohibi ted to raise the speed of turbine turbine if the differential expansion of the turbine rotor reaches to the maximum permissible values.

2.7

At a speed of 1200 rom soak the set for about 20 mts. note that the control valves of HPT tend to close with the rise of speed.

2.9

At a speed of 3000 rpm. hold the turbine at 3000 rpm for about 20- 25 mts, carry out inspection and soaking of the turbine, perform the checking of protection and governing system and tightness test of ESV and control valves

























































































NOTE:

A.

At the speed of 500, 1200 and 3000 rpm note down the following readings in the log book:

B.

i)

Condenser vacuum.

ii )

Axial shift.

iii)

Differential expansion of HPT, IPT and LPT.

iv)

Overall total expansion of HPT, IPT.

v)

Bearing vibration.

vi)

Turbine LPT exhaust hood temp.

vii)

Steam parameter at MSV.

viii)

M.O.P. discharge pressure.

Watch that different metal temperatures have tendency to rise and note down the temperature. temperature .

3.

LOADING OF THE TURBINE

3.1

Synchronize the machine with the grid and take a load of 10 to 15 MW, constantly watch the Differential expansion Axial Shift, metal temp., difference













































3.5

At the load of 30 MW, close the drain valves in LP heater extraction lines, note the thermal expansion of the turbine and all the other readings, charge deaerator by opening the extraction steam valve close if pressure in 2

deaerator is less than 2 Kg/cm .

3.6

At the load of 60 to 70 MW, put the H.P. heaters in service, charge the HP heaters from water side and steam side, close the H.P. extraction drain valves.

3.7

Put the drip pump in service stop the flange and stud heating.

3.8

At about 80 MW load, start the second condensate Dumo 4 BFP and keep the third as standby.

3.9

At about 150 MW load, change over steam supply to deaerator from extraction opening. opening .

3.10

At the load of 210 MW set the point of H.P. bypass valves pressure control loop at 140 ata with the help of push button and change over the manual mode of pressure control loops of HP bypass valves to 'Auto' with the help of push buttons.

3.11

2

Set the L.P. bypass valve pressure set point to 6.0 Kg/cm (ata) and temp. set point to 200°C. Change over the L.P. bypass operation from manual mode to 'Auto' 'Auto' mode with pressure control loop in circuit.













































4.2

Process Chamber heating is required generally during hot start up of turbine. Chamber heating essentially consists of supplying live steam to the HP rotor and IP rotor through the gland seals at a low pressure. This will help in heating the HP rotor and IP rotor thus help in reducing differential expansion.

4.3

Steps to be taken for chamber heating

4.3.1

Chamber heating should be started only when HP differential expansion is more than -0.5 mm and IP differential expansion exceeds exceed s -1.5 - 1.5 mm.

4.3.2

Temperature of live steam should be raised as high as possible and should be higher than the hottest metal temp. of the turbine. 2

4.3.3

The pressure of steam for chamber heating should not exceed 4 Kg/cm .

4.3.4

Chamber heating is to be started while the machi ne is on barring gear. During the process of chamber heating if the barring gear stops chamber heating must be stooped immediately.

4.3.5

During the chamber heating process, shaft eccentricity should be watched carefully, which has a tendency to rise. The process is to be controlled in order to maintain the eccentricity within 0.07 mm.

4.3.6

The following parameters to be noted during the process: process :















































corresponding points. By doing so the turbine may be rolled quickly from cold or warm state.

5.2

Live steam is bled from main steam pipe line before main gate valves valv es of the turbine for heating flanges and studs. The device consists of jackets welded to side wall of casing flanges and special piping complete with fitting and measuring instruments for steam inlet, outlet and drains. Special recesses are provided in the horizontal flanges of the H.P. & I.P. casing joint plane for passage of heating steam to the studs. In the lower half flanges, recesses are provided and in the upper half of the casing along the height of studs there are baffles for guiding the steam flow over the studs.

5.3

The special pipe lines each delivering steam to two separate headers have been provided. Two headers are meant to supply steam to flanges and studs separately.

5.4

The header to the flange jackets supplies steamfor heating flanges. And the header to the recess in horizontal joint of HP & IP casing bottom flanges supplies steam for heating of studs through holes in the bottom flanges on the













































5.8

When starting the turbine from cold or warm (temp. of metal of the upper half of the H.P. casing being upto 250°C), heating of flange and studs is permitted provided differential expansion of the rotor is positive and not less than 1 mm. It is not permitted to operate the flange heating device.

i)

If the relative expansion of rotor compared to casing is less than 1 mm.

ii)

If the differential expansion indicating and recording instruments are either out of order or disconnected.

5.9

In order to maintain proper tightening of flange joints, it is necessary to first supply steam for heating flanges and only then after some time to studs.

NOTE

Due to special constructional features of KWU turbines both the chamber heating and flange and stud heating system is not provided.













































C.

WARM AND HOT START Depending upon the metal temperature of H.P.T. casing in the zone of regulating stage, the type of start can be chosen.

1.

1.1

1)

Metal temperature above 350°C - HOT STAR START T

2)

Metal Temp. between 150°C to 350°C - WARM WARM START START

3)

Metal temp. less than 150°C - COLD START

PRELIMINARIES PRELIMINARIES FOR WARM OR HOT START

Before warm/hot restart, the auxiliary equipment should be started in the same manner and order as in the case of cold start.

Before hot or warm start, the starting oil pump should have been working and supplying oil to bearings, the turbine shaft is rolling on barring gear, and one













































2.

HEATING AND ROLLING OF TURBINE DURING WARM START

Read the actual metal temperature of H.P. casing at the regulating stage and should be within 150°C to 350°C.

By using the temperature matching chart, determine the desired steam temperature and pressure for rolling the turbine. However, the steam temperature must be more (at least 25°C) than the hottest metal temperature of E.S.V. and steam admission pipes of H.P.T.

2.1

Select the operational operational mode of H.P. by-pass by-pa ss valve on 'Manual' and L.P. bypass on 'Auto' and select for pressure mode of operation, set the set point of L.P. by-pass station at 6 ata by push button.

2.2

Set the temperature control loop of H.P. by-pass by-pass station on 'Auto' and set the temp. set point as per the requirement on the down stream side of H.P. bypass station, temperature control loop of L.P. by-pass stations should be on 'Auto' and temperature should be set at 200°C and ensure that the evacuating valves and by-pass valves of NRVS in the cold reheat lines are closed.













































2.6

Manually close the HP by-pass by-pass valves with the help of push button.

2.7

Bring the control of L.P by-pass valves op 'Manual mode' with the help of push button, open the L.P. by-pass valves, with the help of push button when the pressure in the reheat line comes to condenser vacuum close the LP bypass valves.

2.8

Check that the eccentricity and differential expansion of the rotor are within limit.

2.9

With the help of the speeder gear fully open IV, ESV, CVS of IPT and HPT. And slowly open the by pass valves of MSV and roll the turbine as per guide lines given, to the synchronising speed.

2.10

Checking should be made during rolling as in the case of cold start-up.

2.11

Synchronise the set and load the set to 20-30 MW. All the drains must be closed after some load has been taken on the turbine, the raising of steam parameters and loading of the set is to be carried out as per the curve and















































a)

Metal temp. of body of ESV.

b)

Steam admission pipes of HPT and IPT.

c)

HPT in the zone of regulating stage.

d)

Steam admission chamber at IPT.

e)

Body of IV.

Now with the help of steam matching chart, determine the desired steam temperature and pressure for rolling the turbine. Steam temperature before ESV at the time of roll must be more (at least by 25°C) than the hottest metal temperature of elements mentioned above.













































pressure set point, p oint, but the set point valve should be 2-3% 2-3% lower than the value indicated in the instrument, after attaining the desired steam temperature and pressure, suitable for rolling of the turbine, hold the firing rate of boiler.

3.7

Heat the transfer pipes between IV and CV of IPT by opening IV by 5-10 mm as per scale, the valves in the drains of these pipes should be kept full open, prior to the opening of IV, after heating these pipes corresponding to the available steam temperature. Close IV fully.

3.8

Open fully MSV's and IV with the help of the control gear.

























































































D.

TURBINE SHUTTING DOWN FROM FULL LOAD.

1.

PLANNED PLANNE D SHUT DOWN

1.1

Inform the boiler house that the turbine would soon be shut down.

1.2

Check the starting oil pump and also availability of A.C. & D.C. lub. oil pumps.

1.3

Reduce the load at a rate of 3 MW per minute at rated parameters by operating control gear motor.













































1.11

After closure of the Control valves immediately close the main steam valves near Boiler outlet and check that bypass of main steam valves are also closed.

1.12

Stop the other BF pump depending upon the level of the Boiler drum.

1.13

At 2800 rpm, start AC lub oil pump and AC seal oil pump, check the Lub oil press and A.C. seal oil press is normal.

1.14 1.14

When the rotor comes to a stop, start the barring gear and roll the rotor continuously on BG till temp. of lower part of HP casing at regulating stage drops to 170°C, engage the barring gear lever at stand still condition of rotor















































E. 1

IMPORTANT INSTRUCTIONS DURING TURBINE RUNNING ROUTINE CHECKS















































1.7

If any of the control valves gets closed accidentally the load on the turbine would get reduced. Trace out the valve by comparing the pressure reading after all control valves.















































1.12

Turbine operation on load limiter is not recommended for a longtime except in emergency. Such operation hampers control of network frequency.

1.13

General temperature rise in oil supplied to the bearings at constant pressure















































2.2

Do every week

1)

Take out oil tank filters one by one for routine check up and clean by blowing dry compressed air through through them.















































3.8

Do not allow hot rotor to stand without rolling (Barring gear).

3.9

Do not allow to rotate the rotor by hand if there is not at all oil supply to bearings.











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































left in the system then it can cause hindrance to fluid flow, and overheating of boiler tubes causing their failure. Care also must be taken while depressurising. depressu rising. The Th e air vents must be be opened as the pressure approaches approach es atmospheric air.

3.

CHARGING CHARGIN G AND FILLING

3.1

The operations of charging and filling are much the same regardless of the application. The procedure normally followed is:

3.1.1

Open the air vents

3.1.2

Open the drain valves

3.1.3

Start the pump (if the pumps is already in service, open the filling/charging line valve as follows).

3.1.4

Crack open pumps discharge or filling valve until a satisfactory charging flow is obtained (this is usually detected by the sound of the flow through the partially opened valve)

3.1.5

Check that the drain is free from any obstruction and close it.

3.1.6

Expel the air and close the air vent after a steady flow of water has been obtained from it.

3.1.7

While charging, care should be taken to avoid any water hammer. The air must be expelled gradually and completely. To ensure this the rate of charging should be low, this will also avoid overloading of fill pump. The slow charging charg ing is also also essential to avoid thermal stress where there are temperature differences between the water and the item filled.













































4.

WARMING

4.1

Warming differs from charging is that the admission of warming steam results in the production of large quantities of condensate arising from the warming process. This condensate must be drained away before the lower portion of the pipe can be warmed the precaution also must be taken to carry out this operation slowly to prevent large thermal stresses.

5.

DRAIN VALVE OPERATION

5.1

Due to the tremendous amount of damage which can be caused by maloperation, it is important to know the correct sequence in which drain valves must be operated. Almost invariably drain valves are filled in pairs, two valves in series on the same drain line. The upstream valve (valve nearest to source of pressure) is isolating valve and its companion is the regulating valve. Drain lines should be admission up judiciously, avoiding sudden admission of steam or not fluids which could result is large temperature gradients in the drain lines and possibly 'hammer' or thermal shock.

5.2

We avoid this by charging up slowly, throttling the flow of steam or fluid by restricting valve opening, unfortunately, this introduces another problem; as the passage of steam or fluid through the restricted valve opening, creates a phenomenon known as 'wire drawing' or cutting of the valve seats and over a period of time, the valve becomes damaged. To prevent this the valve operation sequence must be as follows : (Refer fig. 12)

FIG. 12













































5.3

Operation

5.3.1

To charge drain line.

i)

Crack open isolating valve. The small length of drain line between the two valves will be pressurised almost immediately. Wire drawing is virtually nil.

ii)

Open isolating valve fully.

iii)

Crack open regulating valve. This valve is subject to wire drawing charge drain line slowly. Regulate as required using regulating valve only.

5.3.2

To shut off drainage.

i)

Close the regulating valve. Wire-drawing Wire-drawing takes place as the regulating valve throttles the flow.

ii)

Close the isolating valve. Flow is already zero. So no wire drawing takes place.

iii)

Crack open the regulating valve to release the pressure trapped between the valves & the regulating valve.

5.3.3

As mentioned, the damage due to wire drawing is inevitable but, at least, by using correct operational techniques we can restrict the damage to regulating valve only. This means that we can reasonably expect the isolating valve to give tight isolation when closed, thus preventing losses via passing drains.

























































































6.

DRUM METAL DIFFERENTIAL The boiler drums are filled with water in the bottom and steam in the top due to which the cooling and heating rates vary between the top and the bottom. This results in temperature differences between the top and the bottom. Stress analyses show that the principal criterion for reliable rates of heating and cooling cooli ng should be b e based on the relationship relationship between betwee n the temperature differential through the drum wall and the temperature differential between the top and the bottom of the drum both measured in same circumferential plane stress analysis also show that the allowable temperature differentials are based on tensile strength, drum diameter, wall thickness, and pressure; therefore, each steam drum has its own allowable temperature differential curves, one set for cooling and one set for heating. To keep the thermal stress values within the limit, operation engineer must ensure that under all operating conditions the actual temperature differential is below the allowable temperature differential. Normally the temperature differential should not exceed 50°C. (Refer fig. 13).

7.

DRUM GAUGE GLASSES GLASSE S

7.1

These give direct measurement of drum level. Normally 2 gauge glasses (sometimes 3) are provided to boiler drum. It must be ensured prior to light up that gauge glasses are available for service and are in charged condition. 2

Especially, during cold start, the remote indication is above 10 Kg/cm . Also during light up operation there are large drum level fluctuations. An about 5 to 2

10 Kg/cm the gauge glasses should be blown from water and steam side to clear of any dirt blocking the ports. As per IBR boiler must not be operated with all the gauge glasses provided out of service.

8.

FLAME INSPECTION

8.1

In a unit operation, boiler is likely to give more trouble than turbine and















































inspection of boiler flame can give where as to whether the combustion is satisfactory or not.

8.2

An oil flame should be yellow and clear with no smoke. As the flame temperature increases the combustion efficiency increases. A yellow flame indicates that oil is releasing the greatest amount of heat energy. A short, white flame or a red, smoky flame indicates lower temperature and a lower efficiency. A white flame indicates too much air and a red flame indicates too little air. Therefore, for a good oil flame, air fuel ratio, air distribution and oil viscosity must be proper. The gun tip orifices must be kept clean.

8.3

The efficient coal combustion also produces a yellow flame, the flame should have an even, regular shape. An uneven flame indicates fouling of the burner nozzles.

9.

SCAPH - OPERATION

9.1

When lighting up the boiler from cold state, since most of the furnace is relatively cool large amount of heat is absorbed in the furnace. This reduces the flue gas temperature leading the boiler. The fuel oil which is fired for light up has 1.5 to 3.5% sulphur depending upon the quality. This sulphur forms SO3 after combustion and combines with H2 O to form highly corrosive Sulphuric acid when temperature falls likely when lighting up the boiler from cold state. Due to large % age of sulphur in oil, special care must be taken when oil is being fired. The sulphuric acid thus formed corrodes portion of an heater and sometimes economise tubes also to prevent this cold end













































10.

BOILER EXPANSION MEASUREMENT Normally for all utility boilers (i.e. power station boilers) the entire boiler, casing and insulation are suspended from top. The provision for free expansion for all parts of the boiler is important but in the case of furnace tubes it is vital. Since the boiler is suspended from the boiler house steel work, the expansion is mostly in downward direction. On a typical 500 MW boiler, the total expansion from cold to full load can be as high as 340 mm. Expansions, in other directions are also significant of the order of 70 to 80 mm. The boiler must be allowed to expand freely in all directions. Scales are provided at different elevations to measure the expansions. Readings must be taken and free expansion must be ensured. This is very important especially when the boiler is being taken into service after major shut down because it is likely that during shut down some temporary piping, scaffolding was welded with the boiler structure.

11.

ECONOMISER RECIRCULATION RECIRCU LATION VALVE During pressure raising period, very little amount of water passes through the economiser and there is a danger of the economiser overheating, and in extreme cases, vapour locking. To prevent this condition the economiser recirculation valve is kept open during the pressure raising period. The recirculation in economiser takes place in similar manner as in water wall tubes. Once a steady flow is established to the drum, economiser recirculation valve can be closed.













































chemicals that can be added to the boiler decrease with rising boiler pressures. (Refer fig. 14). Normally hydrazine is added to feed water to control its oxygen, content. Presence of oxygen beyond permissible limits leads to corrosion of the boiler tubes. Sodium phosphate (usually tri-sodiumphosphate, Na 3 PO4) is used to control the total dissolved solids in boiler water and its PH value. However, the care must be taken not to over doze these chemicals in boiler water as this will also prove harmful to boiler tubes. Maintaining dissolved solids at the level required to prevent foaming requires continuous or periodic blow down of boiler water. The proper treatment of boiler water for high pressure boilers will ensure safe and efficient operation of these boilers.

13.

BARRING GEAR When shutting down hot machine or before turbine start up the turbine must be on barring gear. When a turbine is shut down; due to its heavy weight, high temperature and uneven cooling the turbine rotor will have permanent deformation (hogging/bending). So the main function of the barring gear is to promote even cooling of the steam rotors and cylinders when turbine is shut down. The barring gear is engaged immediately after turbine becomes standstill following a trip. It is safe to carry out this operation locally, though remote start provision is usually provided. The barring speed is usually low (3 to 4 rpm) but high speed barring gears (about 200 rpm) are also common. The provisions of high speed barring gear enables to bring the turbine off barring gear with minimum steam admission while rolling the turbine.

























































































14.

SOAKING OF TURBINE Depending upon the type of the start up (cold, warm, hot), turbine is soaked at some particular RPM for predetermined time interval. During soaking period turbine speed is held constant and steam parameters kept steady. Care should be taken to see that soaking speed is not near critical speed (Turbine manufacturer's recommendations to be followed). Soaking helps in bringing differential expansions within limits, also the operator gets sufficient time to check up other turbovisory parameters like turbine expansion, turbine vibrations, bearing drain oil temp, drain oil flow etc. After satisfying himself of healthiness of turbine he can proceed for further rolling of turbine. The soaking time is more for cold start compared to warm and hot start.

15.

CRITICAL SPEED When shaft or rotor, revolving in bearings, speeds up to where centrifugal force tending to whip it sideways just balances the elastic stiffness tending to keep it straight, the slightest mechanical unbalance builds up a whirling motion, which may be of destructive amplitude. The rotor then is revolving at critical speed. this phenomenon is due to the resonance frequency when the rotation speed corresponds to the natural frequencies of lateral vibration of the rotor. It is inadvisable to run any rotor at or near critical speed for any length of time regardless of perfection of balance. The operation engineer must be well aware of exact critical speeds of the turbine. Care must be taken NOT to hold the turbine speed nearby critical speed value and the speed rise















































limits but close to these limits. Besides by monitoring parameters like make up water consumption, consu mption, auxiliary power consumption, fuel oil oil consumption consumptio n etc., operation engineer can drastically reduce the cost of generation. More make up water consumption not only results in loss of costly D.M. water but also the heat associated with it. More auxiliary power consumption and more fuel oil consumption normally takes place when the unit is operating at part load. The reasons for part loading must be identified and rectified immediately. The operation engineer has a big role to play here.

17.

USE OF COMMON AUXILIARIES

17.1

In a station consisting of number of units, there are many auxiliaries common to all the units. So far the operation engineer it is essential to know how the adjacent units will be affected by his operation. For example, aux. steam supply, fuel oil supply, compressed air supply, cooling water supply, reserve power supply etc. are common for the units. Now if a unit is to be started, before charging say aux. steam header from adjacent unit. They should be informed about this so that in case of any problem it can be immediately













































correct one and investigate the matter. If the result of such investigation proves that there is fault in the instrument, then it should be got rectified from maintenance department immediately. For other parameters also (where only one instrument is provided in UCB for indication) in case of any deviation from standard value, the matter must be investigated and instrument fault must be attended.

18.

SHIFT ROUTINE

18.1

It is observed that large number of mishaps in power station operation take place at the time of shift change over. This shift change over period is such that operator tends to take things easy after days work-out or he is busy in writing log book. So there are chances that he may overlook certain operational parameter going astray. Similarly when some operator takes over the charge, then he is busy in reading the logbook of previous shift. He also may overlook the faulty parameter. Under such circumstances emergency situation can arise. It is important for operation staff, therefore, to take care for avoiding such situation. The logging of each event should be done













































18.2.1

Main A.C. Circuits: Note the position of:

i)

220 KV/400 KV bus bar distribution, distribution distrib ution of feeders, generator and station station transform transformers ers / such questions should be asked: Does one unit feed any particular grid line?

What happens if any grid line feeder on machine trips to the overall position?

ii)

Auxiliary supply position. The position of interconnectors of H.T. and L.T. supply. suppl y.

iii)

Note whether whether the the unit unit is on station or unit supply for HT and LT systems.

18.2.2

Boiler Feed System: Note the feed pumps on load and if the standby pumps are available. Observe whether they are selected to auto or manual.













































ii)

Note mill temperature and see whether controls are on auto or manual.

iii)

Examine P.A. fan differentials differentia ls and see whether they are on auto or manual.

iv)

18.2.5

18.2.6

Check R.C. feeder controllers - see whether on auto or manual.

Combustion Control: i)

Check whether furnace draft is an auto or manual.

ii)

Check whether oxygen control is an auto or manual.

iii)

Check furnace draft reading.

Turbogenerator: Note: i)

Which ejector/air pumps is in service and the position of standby.













































18.2.7

Efficiency Control: Particular attention should be given to following item to monitor efficiency.

(i)

Ensure that all parameters are at their correct valves. Load in particular must not be lower than suggested by grid contro1.

18.2.8

(ii)

Examine milling and combustion. Ensure that they are in good order.

(iii)

Examine D.M. water consumption.

(iv)

Check total total auxiliary power consumption.

(v)

Check condenser vacuum.

Statutory Requirements: i)

Check static condition for grit emission and smoke density. Where these are continuously monitored and each fitted with alarms, this problem is eased.















































vii)

Check state of lighting - particularly emergency lighting.

viii)

Attend to steam, water and coal leaks wherever possible.













































8. 8. 5 500 00 MW M M W W Boi l er O Ope perat i on 1.

INTRODUCTION The modern 500MW unit steam generator is equipped with a comprehensive FSSS which allows the furnace purging and starting of fuel firing system at a predetermined sequence when the set preconditions, as outlined in FSSS logic diagrams, are satisfied. The exhaustive preconditions, if not satisfied, does not allow equipment to be started hence safeguarding the equipment along with the safety of the operating personnel. Following procedures for lighting up and loading the boiler has been discussed keeping in mind all













































6.

Ensure that the two secondary air-preheaters are in service with their gas and air side dampers open. It should be noted that for starting purposes one air preheater is also sufficient but that will allow only upto 5 mill operation.

7.

Start up the two primary air preheaters, if both are available. One air preheater will only allow upto 5 mills to be started.

8.

Check that both ID and FD fans are in service. The furnace draught should be maintained at about-8mmwc and the total air flow should be adjusted by controllling the FD fan blade pitch angle until the flow is 30% MCR. (about 630t/hr.)













































14.

Check that the burner tilts are in the horizontal position.

15.

Select the first oil burner burn er to be fired and start up the burner. Normally when starting from cold, bottom level oil burner (level AB) are taken into service.

16.

After firing any burner check for satisfactory ignition as follows:

i)

Check flame monitor indication shows "Flame in”

ii)

Visually check flame through local viewing doors using suitable eye protection until four oil burners are established. If ignition is found unsatisfactory take out the burner from service.













































If it is necessary to add water to the boiler use the running feed pump and low load feedwater line for feeding.

23.

During the boiler pressure raising and initial loading period carefull carefully y monitor the relative operating parameters of the plant.

24.

Monitor the rate of boiler pressure increase. This must not exceed a corresponding increase in saturation temperature of 100° K/h.

25.

Monitor the drum, superheater and reheater tube metal temperatures. They do not exceed the given limits.















































TEMPERATURE LIMIT OF 540°C. Modulating the steam pressure and temperature by this method permits the unit to attain the highest possible superheater outlet temperature approaching the turbine metal temperature on a hot restart or 55° of superheat during a cold start.















































39.

After the turbine has been synchronised continue raising the boiler load and main steam and reheater pressure and temperature to suit the turbine requirements. At about 20% BMCR drum level 3 element control may be put on auto.















































47.

When boiler load and operating conditions are satisfactory, the first coal mill should be made ready for starting. Ensure that all mill starting requirements have been checked. The first mill will be started when turbine load above 22% and other parameters as per the startup curves.















































iii)

Check the flue gas oxygen, this varies with load as follows :

100% to 80% BMCR

:

3.5% 3.5 %















































The second mill to be started should be preferably adjacent to the first mill in service or the firing oil burners, eg. mill B.

57.

When the mill is in normal operation and furnace combustion has stabilised











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































¶

SHAFT-LIFT-OIL-PUMPS 2

¶

AND 3 DEPENDING ON SHAFT-

¶

LIFT-OIL-PRESSURE.

¶

SHAFT-LIFT-OIL-PUMP 2 (ON)

< 100 KG/CM

¶

SHAFT-LIFT-OIL-PUMP 3 (ON)

< 100 KG/CM

¶

SHAFT-LIFT-OIL-PUMP 3 MUST

¶

ONLY BE OPERATED IF SHAFT

¶

TO OPERATE F. E. DUE TO LACK

¶

OF ACAC- POWER-SUPPL POWER-SUPPLY. Y.

¶

DO NOT SWITCH OFF SUBLOOP

¶

CONTROL OF SHAFT-LIFT-OILSHAFT-LI FT-OIL-

¶

PUMP TO MAKE SURE SHAFT-

¶

LIFT-OIL-PUMP STARTS DURING

¶

COASTING-DOWN COASTING- DOWN AFTER SHUT DOWN

¶

OF THE TURBINE

¶

NOTE!

¶

DO NOT STOP SHAFT-LIFT-OILSHAFT-LIFT- OIL-

¶

PUMP DURING TURNING GEAR

¶

OPERATING UNLESS THE SHAFT

¶

HAS COME TO A COMPLETE STANDSTAND-

¶

STILL AFTER CLOSING THE

¶

TURNING GEAR OIL-VALVE OIL- VALVE

¶

INTENTIONALLY.

2 2

TEMPERATURE CRITERIA The admission steam temperatures should meet the metal temperatures as shown below in order to start and load the turbine in shortest possib le time.

Note:

The criteria above represent approximate values, which can be optimized by operational experience.

Turbines with Functional Group Automatic (FGA) for the start-up must under













































When opening the main stop-valves the main steam parameters should meet the following recommended values.

Steam with 50°C superheat

-

Minimum Mini mum Main Steam Temperature Temperatu re

MS

>

S + 50°C 50° C

MS

=

Main Steam at Steam generator Outlet

S

=

Temperature of saturated steam (depending on main steam pressure)

and MS

>

(MCV 50%)

MS

=

Main Steam temperature temperatur e at Steam generator outlet

MS 50% =

Middle wall temperature of main control valve casing.

MS

>

(MCV 50%)

MS

=

Main Steam temperature temperatur e at Steam generator outlet

MCV 50% =

Middle wall temperature of main control valve

-

Maximum main steam pressure ahead of the turbine

Pmax.

=

(MCV 50%)

Pmax.

=

Maximum main steam pressure ahead of the turbine.













































If the control valve temperatures MCV 50% exceed the temperature of the saturated steam belonging to the main steam pressure the pressure criteria must not be observed.

STARTING CRITERIA When the main control valves are opened the main steam and reheat temperatures temperatures should fulfill the following criteria: criteria:

-

Minimum main steam-te steam-temper mperatur ature e

MS

>

S + 50°C 50° C

MS

=

Main Main Steam Steam temperature ahead of the turbine

S

=

Temperature of aturated steam (depending on main Steam Pressure)

MS

>

(HT 50%)

MS

=

Main Steam temperature ahead of the turbine

HT 50% =

Middle wall temperature of HP-Casing or simulated middle phase Shaft temperature. temperatu re.

-

Minimum reheat temperature.

Reh

>

(IT 50%)

Reh

=

Steam temperature in the hot reheat line

IT 50% =

Simulated middle phase temperature of the IP-shaft.













































SPEEDING UP CRITERIA Before the turbine is brought to rated speed the main Steam temperature MS ahead of the turbine should fulfil the following criteria:

MS

>

(HT 50%)

MS

=

Main Steam temperature ahead of the turbine

HT 50% =

Middle wall temperature of HP-Casing or simulated middle phase Shaft temperature.

LOADING CRITERIA Before the turbine is loaded the reheat temperature ahead of the turbine should fulfil the following criteria:

Reh

>

(IT 50%)

Reh

=

Steam temperature in the hot reheat line

IT 50% =

Simulated middle phase temperature of the IP- turbine shaft.













































WARMING UP AND STARTING UP THE TURBINE CONTROLLERS

1.

Operating modes of the control systems and of the starting and load limit device

Electrical speed control

The turbine generator unit is accelerated accelera ted

- Warm-up operation

and maint maintaine ained d at constant consta nt warm-up warm-up speed

- Running up the turbine/ generator unit

accelerate unit to rated speed maintain unit

high speed governor

at rated speed spee d

Hydraulic governor

The turbine generator unit is accelerated

- Warm-up operation

and maintained at constant warm-up speed by manual actuation of the starting and load limit device.

- Running up the turbine generator unit

When the reference speed setter is in the 0% position, the hydraulic governor takes over speed control at approx. 80% rated speed. So, run-up of the turbine generator unit from approx. 80 to 100% rated speed is

controlled

by

the

hydraulic

speed

governor.

- Rated speed operation

Maintain unit at rated speed acceleration to

- Overspeed trip test

107% of rated speed by the governor; speed is increased to trip speed using acceleration lever on casing of hydraulic governor; During overspeed trip test, the electrical















































Starting and load limit device

- Setting operating con figuration of main trip valves

The main trip valves are brought into operating position when the starting and load limit device is in the 0% position.

- Opening the stop valves

When the starting and load limit device is in approx 40% open position, the stop valves should be open; the test valves must be in the operating position for the opening procedure.

- Warm-up Warm-up operation

2.

see Hydraulic speed governor.

Electrical Elect rical Speed Control Control

Control range in % rated speed

0-107% (limitation by hydra ulic speed

Setpoint control

governor)

- Target setpoint/actual setpoint

The actual setpoint follows the target setpoint along preset gradients.

- Limitation of setpoint by turbine stress evaluator (TSE)

The preset gradient is reduced according to

a

predetermined

characteristic

to

conform to the margin generated by the TSE.













































turbine components must be figured out by comparing the actual temperatures and their

differences

with

the

curves

for

permissible temperature margins.

Limitation by higher - level or alternative controllers or other devices

- Minimum value selection

Effective controller = controller contro ller with the lowest setpoint setting at any time (also applies to other devices influencing the opening characteristic) characteristic)

- Hydraulic speed governor (speed setting device approx. 80%)

- Starting and load limit device

Limits setpoint by hydraulic minimum value selection;

Limits setpoint by hydraulic minimum value selection; excessive control valve opening can be prevented by using the starting and load limit device to limit valve travel.

Operation

see arrangement of control desk release

- Operating elements and monitoring

push button.

instruments













































stress evaluator). During operation with the hydraulic speed governor, the thermal stresses in the turbine components must be figured out on the basis of the TSE display or, if the TSE is faulted, by comparing the actual temperatures and their

difference

with

the

curves

for

permissible temperature margins.

Limitation by higher - level or alternative controllers or other devices - Minimum Minimum value selection

Effective controller = controller with lower set-point setting at any time (Also applies to other devices influencing the control characteristic)

- Electro - hydraulic controller < 100%

Limits setpoint by hydraulic minimum value selection

- Starting and load limit device

Limits setpoint by hydraulic minimum value selection.













































OPERATION

+

Turbine generator unit

=

Turning gear speed

speed +

Stop valve position

=

0%

+

Control valve position

=

0%

+

Main trip valves

=

depressurized

+

Starting and load limit

=

40% open

+

Reference speed setter

=

0%

+

Electrical speed

=

0%

reference

(1)

(2)

(3)

(4)

+

Electrical Electrical speed reference

=

raise raise

+

Electrical speed reference

=

0%

+

Plunger coil

deenergise

+

Plunger coil

deenergised

+

Starting Startin g and load limit device

+


=

+

Main trip valves

in operating configuration

+

Starting and load limit devic e

Raise Raise

lower lowe r

0%













































(5)

+


Raise Raise

+

Control valve

Open

+

Turbine Generator

=

Warm-up Warm-up speed

Unit

(6)

+

Using starting and load limit device

maintain constant speed

(B)

+

Turbine

Warm-up

+

Run-up criteria

=

fulfilled fulfil led

+

Steam generator output

=

adequate adequa te

+

Starting and load limit Device

+

Control valve

=

Open

+

Turbine Generator

>

Warm-up Warm-up speed

=

75% Rated speed

(7)

Raise Raise

Unit Speed +

Turbine Generator Unit Speed

(8)

+


+


Raise Raise

=

100% Open O pen















































Warming up the Main Steam Line B see Warming up and Starting up the Turbine.

+

(1)

(2)

Turbine generator unit speed

>

turning gear speed and 75% rated

<

speed

+


=

turbine generator unit speed

+


=

100%

+


=

56 to 100%

+

Starting Startin g and load limit device

Lower Low er

+


effective

+


Raise Raise

+


=

100% 100 %













































+

Turbine generator unit speed

>

Turning gear speed and 75% rated speed

(1)

(2)

(3)

+


<

100%

+

Plunger coil

=

deenergised

+


=

0%

+


=

effective

+

Plunger Plun ger Coil

energise

+

Plunger Coil

energised

+


lower lowe r

+

Turbine Generator Unit

+


=

electrical speed reference

raise raise













































SYNCHRONIZATION SYNCHRONIZATION AND LOADING (01) (01 )

+

GENERATOR READY TO BE SYNCHRONIZED

CHECK CHECK

+

SPEED OF TURBINE/

3000 RPM

GENERATOR +

DRAIN OF SEAL STEAM HEADER

NORMAL

+

H2-SUPPLY SYSTEM

NO ALARM

+

SEAL-OIL PLANT PLANT

NO ALARM

+

PRIMARY WATER SYSTEM

NO ALARM

+

LIQUID IN GENERATOR

NO ALARM













































+

(04)

AUTOMATIC AUTOM ATIC SYNCHRONIZE SYNCHR ONIZER R

ON

------------------------------------------------

----------------

+

GENERATOR VOLTAGE CONTROL

CLOSED

+


SWITCHED ON

OR WITH (AUTOMATIC SYNCHRONIZER)

(04/S)*+

(05) (05 )

+


SWITCHED ON

------------------------------------------------

----------------

SYNCHRONOCOPE SYNCHRON OCOPE

SWITCHED ON


+

SYNCHRONOCOPE SYNCHRON OCOPE

SWITCHED ON

------------------------------------------------------------

-----------------------------------














































(08/S)*+

GENERATOR / LINE- FREQUENCY FREQUENC Y ¶

GENERATOR FREQUENCY

¶

MUST BE ADJUSTED IN SUCH A WAY

¶

THAT THE NEEDLE OF THE

¶

SYNCHRONOSCOPE SYNCHRONOSCOPE TURNS

¶

SLOWLY IN THE DIRECTION

¶

GENERATOR FREQUENCY HIGHER

¶

THAN LINE FREQUENCY=

¶

FAST SYNCHRONIZING.

¶

FAST SYNCHRONIZING ENSURES

¶

THAT THE GENERATOR WILL

¶

BE LOADED IMMEDIATELY

¶

AFTER SYNCHRONISING THUS

¶

PREVENTING REVERSE POWER

¶

RELAY TO BE ACTUATED. ACTUATED.

MET















































(10) (10 )

(11) (11 )

+

SPEED REFERENCE VALUE

SET HIGHER

+

GENERATOR GENERATO R LOAD

> 10%

------------------------------------------------------------

-----------------------------------

+

STARTING AND LOAD LIMIT DEVICE

SET HIGHER

+

STARTING AND LOAD LIMIT DEVICE DEV ICE

100% 100 %

OR WITH FGA (TURBINE CONTROL)













































(13) (1 3)

+

(13/S) *+

WAIT

LIMITED LOAD REFERENCE VALUE ¶

THE LIMITED LOAD REFERENCE

¶

VALUE FOLLOWS THE TARGET LOAD

¶

REFERENCE VALUE WITH THE

¶

ADUSTED LOAD GRADIENT.

¶

THE LOAD GRADIENT WILL BE

¶

REDUCED, IF REDUCTION OF THE

¶

TSE-ALLOWANCE OCCUR.

¶

THE TSE INFLUENCE WILL BE

HIGHER













































+

+

¶

CRITERIUM:

¶

TEMP. TEMP. HP-CASING TOP

DRAIN AHEAD OF SWING-CH SWING-CHECK ECK CRH ¶

CRITERIUM:

¶

NON RET. CHECK VLV COLD REH.

> 320 CEL CEL

CLOSED

OPEN

DRAIN UPSTREAM RCV

CLOSED

¶

CRITERIUM:

AND

¶

VALVE CASING TEMPERATURE

> 50 CEL

¶

MINUS SATURATION TEMPERATURE

¶

OF STEAM

Power Plant Operation

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