3.boiler operation

7/30/2019 3.Boiler Operation

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Vung Ang No.1 Thermal Power Plant

BOILER TrainingOperation


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content1. Overview.

-

3. Various kinds of the boiler start-up curves.

4. Valves operation in the various stages.

. .

6. normal operation adjustment.

7. combustion tuning.

. rou es oo ng.

9. Operation control picture.

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1. Overview

1.1 Boiler start-up division.

1.2 The ways of the boiler start-up and shutdown.

. -

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1.1 Boiler start-up divisionGenerally the sub-critical unit, according to the temperature of the

high-pressure cylinder, boiler start-up is divided as follows:zCold boiler start-u : tm180.zWarm boiler start-uptm180-350 .zHot boiler start-uptm350 .zVery hot boiler starttm 450

It is also divided into different kinds according to the boiler downtime.zVery hot boiler start-up:t1h.

zHot boiler start-up:t8h .

zWarm boiler start-up: 8h t 72h.

zCold boiler start-up:t72h

Boiler cold start-up there is no pressure in the boiler and its.

Other kinds of the boiler start-up are similar to the cold boiler start-up. There is pressure and temperature in the boiler. They can beconsidered as the cold boiler start-up with starting certain periods and

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before the point, the work can be omitted or simplified.

Tua bin cao ap


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1.2 The ways of the boiler start-upIt will be used by the method of the turbine-boiler united sliding parameter to start

and stop.

According to the turbine design, there are two kinds of ways to start the boiler: steamgo n o g pressure an me um pressure cy n ers a e same mes. s eam go n omedium pressure cylinder.

The main valves of the turbine will be shut down before the ignition and certain timeafter the i nition. However s eed steam valves are full o en. The steam that is su lied

by the boiler through the high and low pressure bypass is sent into the condenser. Thesteam volume will controlled by the valves fixed on the bypass system.

In the process of the turbine-in turn, speed up, warm and synchronization of,

condenser through the pressure bypass. When main steam valves is fully opening, closethe bypass. The unit entered the sliding pressure operation. In the end the boiler

arrives the rated parameters and the turbine achieves the rated power.s ng e s ng pressure opera on, can ea e ur ne y e ow-vo age, ow-

temperature steam. It can reduce heat stress and start-up heat losses. At the same timethe superheater and reheater cooling has been improved. It shorts the start-up time. Itreduces heat loss.

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1.3 Securit and efficienc in the start-u

Compared with the normal operation, due to the work pressure andtemperature changes at any time, the boiler conditions is more complex. Sot e our areas t at we s ou not ce s as o ows: The temperature of the components and working substance change at anytime. As heating can not be completely uniform and the variouscom onents in different arts of different tem eratures it will inevitabl

produce thermal stress. In this period we must protect the drum, headers,pipes, valves, etc from damage. The water cycle is not normal. The water wall is heated relatively largely.,

the flow is partial and small in the short time. If the heat is too strong,parts of the water wall, superheater, reheater might exceed the

temperature that is allowed to use. or sma amount o ue nput, ow temperature, unsta e com ust on, tneed to prevent fire and explosion to prevent equipment from damage. Except heating the surface, there is some loss in the exhaust steam,draina e and heat loss. In low load sta e the loss in the combustion is also

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large.


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2. Boiler cold start-up process

2.1 Start-bypass system.

2.2 Cold start-up procedures.

2.3 Necessity to control the rising speed of the temperatureand pressure.

2.4 The preparatory work for cold start-up.

2.5 Ignition2.6 Turbine rolling, raising speed, synchronization

2.7 Risin u to the s ecified load.

2.8 Raising load.

2.9 Attentions

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2.1 Start-bypass systemstart-bypass system is assembled by boiler steam and water emission

system, and turbine I, II-bypass system.Start-b ass s stem: It will be used when the ower units start andshutdown or have emergency. Its function is to balance the steam between theboiler and turbine, to coordinate with the boiler combustion, to protect andregulate the power unit.Boiler emission system:

In the boiler, emission ports and valves are set on all the headers, forexample superheater headers, reheater headers. Ports for other boiler steamflowing are set in the bottom water headers in addition.Turbine I, II-bypass system:I-bypass is high pressure steam bypass and it matches the high pressurecylinder of the turbine. II-bypass is low pressure steam bypass and it matchesthe low pressure of the turbine.

Before the turbine runnin the steam flows into the condensers throu h I-bypass system, reheater system, II-bypass system. This will regulate thevolume of steam that flows into the turbine and protect the reheater system.Through opening the I-bypass system, it can improve the reheatertemperature and cool the reheater system.

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2.1 Turbine I, II-bypass system

The steam supplied by the boiler will not pass through superheater system

or turbine partly or completely. It will flow into the condensers passing.

volume of the steam between the boiler and turbine. At the stage of starting,it can also coordinate the steam temperature between the boiler and metaltemperature of the turbine.

en tur ne runn ng, ensure certa n open ng o , - ypass system, sothat the pressure and temperature of the steam will achieve or be close tothe design, will decrease the stress and lifetime of the turbine and willreduce the start time.

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2.1 Turbine I, II-bypass system

When the load changes greatly in the short time, the rate of the boiler is

smaller than the rate of the turbine. The steam flows through the bypass,

condition.

It can recycle the working substance and decrease noise of putting out thesteam.

When the rate of the turbine is changing, it can stop the turbine withboiler running to use the bypass.

When the power units only supply electricity for itself, it can reduce the.

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2.2 Cold start-up procedures

The sequence of cold start-up includes: to complete the all preparation workbefore startup to fill up water to blow the furnace igniting and warming

up turbine rolling starts and increase the turbine speed Electric Generator

synchronization to shut down the bypass system, start to burn coal and

ncrease t e o er oa o er ow own to operate.

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2.2 Cold start-u rocedures

The general procedure of boiler start-up

(1) To i nite and setu the initial coal consum tion, drain vales for each heatinsurface should be controlled, which will be used to warming up and drain outall deposit water.

(2) Before TBS system put into operation, steam generated by boiler should be,

shall be drained by the water during ignition. The exhaust valve and drain valvewill be close when the turbine bypass is in running, the steam flow will beadjusted by the turbine bypass at this time. In order to maintain the required

, ,the exhaust steam flow, drain and bypass flow should be controlled.

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(3) Attention should be paid to the water circulation, drum water level and t ofdrum wall during the startup. The water quality should also be inspected, and

quality.

(4) In case that the steam parameter meets the requirement, turbine will be started,and gradually increase the turbine speed, warming up and connect to the powergr or n a oa . s e me o s ar e coa supp y sys em an ncrease e

coal input gradually.(5) While the steam flow from boiler outlet is same as that of the turbine inlet, the

o erator shall increase the coal flow rate. The unit will start to follow slidinoperation model to increase pressure, temperature and load, and get the BMCRload finally (or the required load).

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(6) While the boiler load is stable and furnace combustion is well, auxiliary oilsystem will be shutdown, and the combustion will wholly relay on coal.

(7) The steam temperature at SH outlet should not be higher than the allowablemaximum temperature of IP turbine inlet and not lower than that of allowableminimum.

(8) It should try to increase the RH steam temperature since it is normally low. ,

temperature should not be higher than the allowable maximum temperatureof MP turbine inlet, and not be lower than that of allowable minimum.

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After all required general preparation has been done, the boiler water

will be filled up to the startup level, which is little lower than the

Oil ignition and furnace purge could not be taken until the auxiliarysystem parameter of neighboring boiler meet the start up

.

The boiler startup procedure normally includeswarming upboilerturbine rollingynchronization and load increasing

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2.3 Necessity to control the rising speed of

the temperature and pressure

Must control the temperature and pressure rising speed,Because of:1In the process of the boiler cold start-up, the boiler changes from cold to hot.There will be a lot of the stress in certain parts of the boiler and turbine,especially thick parts. So it is necessary to control the rising speed of the

, .2If the temperature and pressure rising too quickly, the combust rate will

increase. So at the beginning of the cold start-up, the condition is as follows:

- .

The quantity of the steam in the superheater and reheater is still smal.

The flowing in economizer is zero sometimes (stop water supply).o oo g com us ra e w cause oo g empera ure n cer a n par s owater wall, the big stress, also too high temperature in certain parts of thesuperheater, reheater and economizer. So it is necessary to control the risings eed.

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The allowance Temperature increase rate

atureIncreaseRat

SaturationTe

m

e

Temperature increase oCAllo

Initial temperature

17Initial drum pressure Mpa


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The allowance Wall temperature difference During Operation

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Drum pressure rising curve19

The Curve Of Relationship

Between Allowance Boiler1516

17

Pressure and Time Cold Start-up

12

13

14

aPlease work in the

8

910

DrumpressureM

curve right side.

the curve is based on the allowance5

6

7

saturated temperature increasing

ratio 111/h1

2

3

19

0

0 20 40 60 80 100 120 140 160 180Time-minute


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2.4 The preparatory work for cold start-up

1) Examine and ensure all the systems have the start-up conditions.

2) If possess the condition of the water supply, start the water pumps and pumpwater into drum through the water supply bypass system. Monitor the water levelwhen the drum has the lowest level. Pay attention to monitor temperaturecontrast between the upper drum wall and below drum wall, not exceeding 50.

.

level have reached -100mm, stop the supplying water and open the recycle valvesof the economizers.

4) Air blow in the furnace has been completed.

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2.4 The preparatory work for cold start-up

5) All the meters is qualified, for example, flame meters. The power unit connect,

MFT (main fuel trip), OFT (Oil fuel trip) and other protect set are qualified.e ore e o er gn on, us ng e s eam supp e y aux ary o er o ea

the water, so that it can reduce the start-up time and save the oil for starting.The parameters of the steam are about 350, 0.98MPa and flow is about 50t/h.It can raise the pressure to 0.49MPa.

7) After satisfying the ignition condition, close the beside boiler and ignite with oil.The process of the heating should be slow. The temperature rising speed of thedrum wall should be less than 1.5 /min. The allowed temperature contrastbetween the u er drum wall and the lower drum wall is accordin to dia ram .

8) Prevent that steam temperature is too low and water flows into the heating pipe.

9) Start the air heater, and use hot wind recycle system to protect the air heater.

10) Re ulate the furnace air ressure, re are to i nite.

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.

Get the ignition picture of the FSSS from DCS, check the ignition condition..

After ignition, monitor the water level and water quality. Start the systems ofthe blow-off, medicating and sampling. Control the combust and ensure thefurance outlet air tem erature is lower than 538 the tem erature difference ofthe upper and lower drum wall is less than 50

.

Control the valves for drainage fixed on the heat surfaces to warm the pipes anddrain the water. After all water has been drained, shut the valves timely to protectheat surfaces. But the valves for the drainage fixed on the superheater system canbe closed late because they can low the pressure.

Stop boiler water supply, start the recirculating system to protect theeconom zer.

Control the combustion rate and turbine bypass systems to regulate the steam flow.Thus it can control the speed of the steam pressure and temperature.

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down


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2.6 Turbine rolling, raising speed,

synchronization

Along with combustion rate increasing, the steam parameters achieve the parameters requested by theur ne ma n eam empera ure s . e pressure s . a. e s eam ow s re ea erSteam temperature is 300.the pressure is 1.01MPa). Before the turbine running, ensure the steam isqualified and the level protect system has been started.

Control the steam tem erature and combustion rate and use the hi h and low b ass s stems to control thesteam parameters. If necessary, start the temperature reducing system and drain valves fixed on the

superheater to control the steam. Pay attention to water level and pressure in the drum.

After the turbine rolling, gradually turn off the valves fixed on the bypass systems. The steam will passroug e ur ne. can sa s y e ur ne runn ng an pr mary oa a ou avo ng oo muc

adjustment in combustion.

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2.6 Turbine rolling, raising speed,

synchronization

,of the steam. The turbine maintain the running speed and the generator is on

synchronization. When the opening of the turbine valves is 90%, usually completely

c ose e va ves o e ypass.

After on synchronization, increase combustion and pressure in the drumaccording to P19 . Control the temperature rate of the main steam at about

0.73/min until it achieves desigh value 541. Control the temperature rate of thereheater steam at about 0.85 /min until it achieves specified value 541. After on s nchronization o en the dam er fixed at reheater side and then set itauto. Check the drain valves of the reheater have been closed. Make sure that the

probe for measuring the wind temperature has been quitted.

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2.7 Rising up to the specified load

After the turbine has primary load, the steam completely flows into the turbine.e urnace an o w n empera ure ave een ra se g . s me, gn e

the burners with coal gradually.

Then regulate the boiler combustion. Power unit raise the temperature and loadaccordin to the start-u curve risin s eed of the tem erature is less than1.5/min and the pressure less than 0.1MPa/min). However, load rate is mainlycontrolled by the turbine, not by the boiler, so load rise up to the target valueaccording to the turbine request.

,steam pressure achieved. Steam pressure can achieve the specified value earlierthan the load (depending on the opening of the turbine regulating valves). If the

steam pressure achieves the specified earlier than the load, increase the opening of. ,raise the load to specified value.

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2.8 Raising load

During the load raising, start the primary air fan and make them auto-. .

z Start one mill, pay attention the drum water level and otherparameters, and control the combustion.

, .

properly.z Start the steam temperature control systems to avoid the temperatureof the su erheater and reheater too hi h.

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2.8 Raising load

zWhen rising to 10% BMCR, change the steam resource of AH

sootblower by boiler self.zWhen rising to 15% BMCR, run steam temperature control system

zWhen rising to 20% BMCR load, open the main water supply valvesrun the feedwater control system. Now water supply will according to

, .

control the drum level by feedwater bypass valve opening.zWhen rising to 40% BMER load, check the quality of water andsteam. If not good, stop raising load and increase the opening of blow-o va ve an e m na e e s con un e qua y o e s eam s goo .

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1

0.8

0.9

rve

0.6

0.7

(ppm)

tentC

tion

0.4

0.5

WaterSilicaConte

Con

Oper

0.2

0.3

ilico

u

ring

0.1

The

28

0

8.00 10.00 12.00 14.00 16.00 18.00 20.00 22

MPaDrum pressure Mpa


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2.8 Raising load

zWhen boiler load is more than 50%BMCR, start the boiler interlock systems and

alarm systems.en t e rst m oa ac eves - , start t e secon .

zWhen the two mills load achieves 60-70%BMCR, start the third and reduce the oil

guns gradually.

zWith boiler load rising, start the fourth and the fifth.

zWhen the combustion is stable, we can stop all the oil guns.

z

whole blowing.

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2.8 Raising load

zWhen superheater and reheater steam temperature is above 530, auto.z Base on the operating condition, BMS, CCS, and SCS will operateautomatically.

zAll the drain valves and vent air valves should be o ened before i nition.

zThe rising rate of temperature, pressure and boiler load must be strictlyaccording to the start-up curves.

zThe metal temperature difference between the upper and the lower ofrum s ou no e more an .

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2.9 Attentions

Maintain the water level at 0 +/- 100 mm

Set the regulation of the coal and air fully auto or manual so that it cancoor na e e coa w e w n an can avo e e ona on.

Maintain the oxygen: 8-10 at the time of the ignition. Boiler water is qualified.

When start the pulverized coal feeder, avoid temperature at the exports of the

pulverized coal feeder too high (not more than 130 . Forbid to ignite the burner with beside burner.

After coal on fire, pay attention to the pressure wave motion in the furnace,flame, and combustion stability.

According to the load and start-up condition, increase the fuel and air. Regulatee secon ary a r o ma n a n pressure con ras e ween e w n ox an e

furnace is about 1.5Kpa.

Timely start the reducing temperature systems to control the temperature.

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3. Various kinds of the boiler start-up curves

3.1 Boiler Cold Start-up curve

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3.2 Boiler Warm Start-up curve

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3. 3 Boiler Hot Start-up curve

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3. 4 Boiler Very Hot Start-up curve

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3.4 Valves operation in the various stages

Valves

Valves operation

e ore s ar -up ar -up n sync ron za on

Air valves in the drum Open When 0.180.34MPa,

close the valves

Close

Steam sampling If necessary, If possible, open the If possible, open the valves

open the valves valves

Water sampling If necessary,open the valves

If possible, open thevalves

If possible, open the valves

Blow off If necessar If ossible o en the If ossible o en the valves

open the valves

valves

Water meters Open Open Open

Water drain meters Close Close Close

Medicating If necessary,

open the valves

If possible, open the

valves

If possible, open the valves

Economizer import header drain valves Close Close Close

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= Blow down


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Economizer recycle pipes When water supply, close the Closepen valves

Focus downcomer drain valvesClose

Close Close

Ceiling import header drain

valvesOpen

When 0.180.34MPa, close the

valvesClose

Lower header at surrounding

i es and horizontal flue OpenWhen 0.180.34MPa, close the

valves Close

Shield superheater import

header drain valvesOpen

When 0.69MPa, turn down

the valve

When 5%, close

the valves

Su erheater im ort header When 0.69MPa turn down When 5% closedrain valves

Openthe valve

the valves

Superheater export header

drain valvesOpen

When 0.69MPa, turn down

the valve

When 5%, close

the valves

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Reheater import header If necessary, open If necessary, open the valves Closedrain valves the valves

Reheater export header

drain valves

If necessary, open

the valves

If necessary, open the valves Close

e super ea er expor

header deflation valves

pen en . a, urn own

the valve

en , c ose

the valvesSuperheater export header

deflation valves

Open When 0.69MPa, turn down

the valve

When 5%, close

the valves

Reheater export header

deflation valves

If necessary, open

the valves

If necessary, open the valves Close

Upper economizer header Close Close Closedeflation valves

Superheater connection

pipes

Open When 0.180.34MPa, close

the valves

Close

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5. The boiler shutdown

The boiler shutdown is divided into two types: normal shutdown

(planned examination or reserve) and accident shutdown. The latter is.

The time of planned examination is long and it requests the boiler coolsdown. However the time of the reserve is short and the boiler maintainshot.

All the planned examination, reserve or accident boiler shutdowns

adopt variable parameter means. The boiler and turbine combines sothat it can make the unit cool down fast.

Preparation. decrease the load. Turbine slowing down. Stop thecombust. decrease the pressure and cool down .

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5.1 Boiler operation in the shutdown

Preparation: blowing ash etc. Decrease the load: according to certain rate, for example: 1.5% MCR/min. The

burners also decrease and at the time we can use oil to assist. With the fuel reducing,

decrease the wind but the total of the wind not less than 30%.

Turbine slowin down: when turbine slowin down, start the b ass s stemsand continue to decrease the boiler load.

When the boiler load is about 5%, stop the combustion. Then we should controlthe ressure and coolin down s eed. The su erheater and reheater drain valves can

be opened for some time.

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5.1 Boiler o eration in the shutdown

When the boiler cools down, finish the furnace blow. Then the boiler can be.

For the reserve boiler, after blowing, stop all the fan and close the damper. If urgent shutdown, after blowing, start the fan to cool down the boiler. If the smoke temperature is less than specified value(150 ), we can stop the

air preheater.

er s opp ng e wa er supp y, s ar e econom zer recyc e va ves.

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5.2 Boiler storage after shutdown

Shutdown storage:

a er s u own, e c em ca epar men can a e re a e measures o

reduce and avoid internal corrosion of the heating surface according tothe duration and purpose of shutdown, and then carry out as required bychemical su ervision. Maintenance of the boiler is divided into wetstorage and dry storage

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5.2 Boiler storage after shutdowne s orage: s a e carr e ou as o ows accor ng o ma n enance

duration and maintenance requirements of each pressure part.

Maintenance periodEconomizer,

water wall

Superh

eatersteam Reheater

steam pipe of

Filled with

Short

-term

Within

one weekpressurization

=

withFilled with

nitrogen

No

treatmentNo treatment

NH3=10mg/l

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More than

one week

Filled with water+

nitrogen pressurizationFilled

with

Filled with

Filled

with Filled with

an w n

one month

2 4= mg

NH3=10mg/lnitrogen

n rogen n rogen

n rogen

More than Filled with water+

one monthand within

nitrogen pressurizationN2H4=700mg/l

Filled

with

nitro en

Filled withnitrogen

Filled

with

nitro en

Filled withnitrogen

ongte

rm

six months NH3=10mg/lL

Filled with water+Filled Filled with Filled

months N2H4=1000mg/l

NH3=10mg/l

with

nitrogen

nitrogen with

nitrogen

nitrogen

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.Operation methods for short-term maintenance: shutdown the boiler in normalway: after fire off, the chemical department shall add ammonia and diamine

solution, tightly close the furnace, keep the air valve at the outlet of HTsuperheater open, and maintain natural circulation inside by residual heat whenthe temperature of boiler water drops below 180. and then close it when thetemperature is lower than 150. The concentration of diamine solution in each

,

200mg/L and PH value is about 10 as controlled by the chemical department.When the drum pressure is lower than 0.2MPa, still close each air valve, open

nitro en b ass relief valve confirm that nitro en ressure is above 0. 30MPathen open nitrogen charge valves of the steam drum, the superheater and themain steam tube to fill nitrogen.

Keep 0. 034Mpa nitrogen pressure in the steam drum and the superheater duringmaintenance, see below.

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5.2 Boiler stora e after shutdown

Operation methods for long-term maintenance

Shutdown the boiler in normal way. After fire-off, the chemical department shall, ,

valve at the outlet of HT superheater open, and maintain natural circulationinside by residual heat when the temperature of boiler water drops below180. and then close it when the temperature is lower than 150. Theconcentration of diamine solution in each part of the boiler shall be even.

When the drum pressure is lower than 0.2MPa, still close each air valve, opennitrogen bypass relief valve, confirm that nitrogen pressure is above 0. 30MPa,

en open n rogen c arge va ves o e s eam rum, e super ea er an emain steam tube to fill nitrogen.

Keep 0.034MPa nitrogen pressure in the steam drum and the superheater.

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When the main steam temperature drops below 100, close nitrogen chargevalves of the steam drum and the superheater, open Level I attemperating

water valve, and slowly open the air valve of main steam tube to fillem nera ze water n t e super eater, re er to t e a ove st or

concentrations of diamine and ammonia. When water is overflowing from theair valve of main steam tube, then close it and Level I attemperating watervalve, stop water filling.

After the superheater and main steam tube are filled with water, still open the

nitrogen charge valve to maintain 0.034MPa nitrogen pressure in the steamdrum, the superheater and the main steam tube.

,water temperature and wall temperature of the main steam tube shall be50, pay attention to pressure of the superheater when filling water to avoidover pressure.

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5.2 Boiler after shutdown

Protection of the reheater

a) When pressure of the reheater drops to 0. 20MPa, still close the air valve of it,open n rogen ypass re e va ve, con rm a n rogen pressure s a ove0.30MPa, and then open nitrogen charge valve of the reheater to fill nitrogen.

b) When tube wall temperature of the reheater drops to 100, close nitrogen, ,

slowly open air valve of the reheater to fill demineralized water in the reheater,refer to the above list for concentrations of diamine and nitrogen in water.

cWhen water is overflowin from the air valve close it to sto water fillin .

d) After confirming that the reheater is filled with water, still open its nitrogencharge valve to fill nitrogen, and maintain above 0.034MPa nitrogen pressure in

the reheater system.

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Precautions for wet maintenance

Frequently check and ensure that nitrogen pressure in each system is above. a n ma n enance.

If the equipment has to be overhauled after shutdown, it only needs todischarge water in the overhaul part, which shall be filled withdemineralized water containin ammonia and diamine and nitro enafter overhaul.

As for short-term maintenance, test the water quality at the beginning. whilefor long-term maintenance, it needs to regularly test the water quality.

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Dry maintenance

In order to dry the reheater, DO NOT open HP/LP bypass, only open the air valve of

HT reheater after shutdown of the turbine. shutdown the boiler after continuousrunning for one hour, control gas temperature at the outlet of furnace


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After shutdown, when temperature of the boiler water is


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Maintenance during overhaul or repair:

If the boiler unit has to be overhauled after shutdown, wet or dry maintenance is unavailable, apply

passivation before shutdown to form a passivation protection film on the inner surface of the tube wall,so as o avo corros on o o er n over au . ass va on opera on s s own as o ows:

Shutdown the boiler in normal way, still keep one water pump running.

When temperature of the boiler water drops below 180, the chemical department shall addammonia and diamine solution, control 300400mg/L diamine in boiler water and PH value about

. . eep e am ne concen ra on, g y c ose e urnace, eep e a r va ve a e ou e o

superheater open, and maintain natural circulation inside by residual heat when the temperature of

boiler water drops below 180. and then close it when the temperature is lower than 150. Theconcentration of diamine solution in each part of the boiler shall be even.

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When pressure of the steam drum drops to 0.78MPand 0.39MPa, carry outintermittent blowdown respectively for half a minute.

eep . a pressure o e s eam rum or a ou wo ours n conven ence orforming a passivation protection film on the inner wall of tube.

When the pressure drops to 0.2MPa, open all air valves, discharge valves and drainvalves for water draina e of the hot boiler .

If the overhaul lasts for more than one month, on the basis to dry with surplus heat

during water drainage of the hot boiler, bibulous silica gel shall be installed inthe steam drum, lower water drum, economizer and superheater header.

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6. normal operation adjustment

The boiler operation refers to the motion which is after the power unit start-up. In

The main work in the boiler running is to monitor and regulate the various

parameters, to satisfy the demands that the turbine requests, and to make sure

.

In the boiler running, kinds of the parameters are changing all the time. Constant isrelative. Boiler running is a moving process. The boiler will be affected by

, .

running is to maintain the parameters changing in safe and economic areas.

The running is divided into two types: auto regulate and man hand regulate. The

plans.

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6.1 operation and control task

Make sure that the boiler parameters achieve the specified value and satisfy the

turbine request.

.

Make sure that the water and steam are qualified.

Balance the water supply, and maintain the water level in the drum.

Maintain the good combustion, reduce the heater loss, and improve the boiler

efficiency.

Timely regulate the boiler running, and make the boiler run in the safe and

economic condition.In the boiler running, auto equipment will be used to

monitor the parameters. If necessary, we can regulate the parameters by

manual.

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6.2 Monitor and adjustment contents

The main parameters in the boiler are as follows: primary steam pressure,primary steam temperature, reheater steam temperature, water level,furnace pressure, etc.

n or er o ensure e o er runs sa e y an econom ca y, var ousparameters should be monitored and controlled.

z Load

z Steam temperature

z Water and steam quality

z Boiler soot-blowin

z Water level and metal temperature in the drum

z Metal temperature in the heater surface

zWet e ui ment o eration

z Boiler running and prevention law

z Coordination control, interlock and alarms

z Combustion adjustment and furnace pressure

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6.3 normal operation adjustment

6.3.1. Adjustment of boiler load:

increase or reduce fuel amount, load change rate when the boiler is

loading on or loading down is shown as follows:

..50%70%BMCR: 3%/min..Above 70% BMCR: 5%/min.

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6.3.2 Steam pressure

When the boiler runs at the constant pressure, we should maintain theprimary steam pressure at various loads. If the steam pressure is too low, theheater loss of the power unit will grow. If the steam pressure is too high, it is.

When boiler running normally, maintain the steam pressure waves at designvalue: 0.138 Mpa. .

severely.

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6.3.3 Control of water level of the steam drum

During boiler operation, the normal drum water level will be at centre line of drum.The permitted fluctuate range of normal water level will be 100mm alarm and

blowaboveItem

Required-150LOW WATER ALARM

Automatic after 20 sec time delay-230BOILER TRIP LOW WATER LEVEL

Required+150HIGH WATER LEVEL ALARM

-

AUTOMATIC+230BOILER TRIP HIGH WATER LEVE

Automatic (after 20 sec time duration)+200BOILER TRIP HIGH WATER LEVE

59Optional+762BOILER FEEDPUMP TRIP


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Water level of the boiler shall be based on the indication of in-situ differential pressure. ,

drum water level sampling tester to check the in-situ water gauge under ratedsteam pressure when it is running. At least two accurate in-situ water levels are putinto use for monitoring the water level as the basis for adjustment in startup,

.

Try to put feedwater adjustment in auto mode and still strengthen the monitoring ofwater level. Refer to the adjustment of steam and feedwater flow when the automode fails and it switches to the manual mode. DO NOT increase or reducesuddenly and avoid great change of the water level.

Frequently pay attention to the feedwater pressure, if it influences water filling, contactthe turbine department to increase the feedwater pressure or startup the standby

supply.

In normal operation, DO NOT use the emergency drain valve to adjust the water level,close the recirculation valve of economizer tightly to avoid water entering the steam

60

.

In normal operation, each shift shall check the indication of water gauge of steam drum

in the master control room and the in-situ water gauge, and shall wash the watergauge if it is inexplicit or the water level is dull.


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Strengthen monitoring and adjustment of water level in the following cases:1.Supply pressure and flow change greatly.

2.The safety valve is activated or returned and the boiler is blowing down.

3.The load is changing and the HT heater trips.

4.Startup/shutdown the feed pump, carry out impulse starting and synchronization

when starting or stopping the boiler.5.The feed pump and regulation device are out of service.

. .

7.When switching the regulating valve control and rotation speed control of the feedpump, and two electric pumps.

8.Bearin arts are leakin .9.When opening or closing regulating valve and bypass valve of the turbine, as wellas drain valves of the superheater and main steam tube.

10.When the combustion is instable or in flame blackout.

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ay a en on o m sys em an e m na e e uncommon p enomenon, or

example, out of coal, coal block. Especially note the steam pressure changes

when the mill system is in uncommon condition, for example, start-up,

, , .

Pay attention to the steam pressure and timely regulate the pressure whenthe load changes.

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6.3.5 Adjustment of steam pressure and

evaporation. ,

it also can be realized through changing the evaporation of boiler or load of theunit. Outlet pressure of the superheater is controlled at 17.350.2 MPa.g, steampressure of the reheater changes with the main steam pressure, its outlet pressure

. .

2.When the boiler is running at sliding parameters (the speed regulating valve of theturbine is fully opened, steam temperature is ensured at specified value, steampressure and load for operation are adjusted through combustion of the boiler, thisis called as operation at sliding parameters.), the steam pressure shall changestably and slowly. Control of steam parameters at each stage is shown below:

Operation condition B-MCR 100%RO 75% RO 60% RO 45%RO 30% RO

Main steam pressure (MPa)17.43 17.29 13.48 10.66 8.25 5.97

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6.3.5Adjustment of steam pressure and evaporation

3When the steam ressure is under auto control, still stren then monitorin to avoid overmodulation or under modulation. when switching the failed auto mode into manual mode,pay attention to the smoothness and lead of adjustment as well as the mix proportion of airand coal.

4When HT heater of the turbine fails and stops, avoid over pressure of the reheater and overtemperature of the superheater. otherwise, properly reduce the load of boiler.

5

Pay attention to check HP/LP bypass to avoid over pressure of loss of pressure of the reheaterin normal operation.

6Avoid great increase or reduction of air quantity and coal in operation to avoid rapidfluctuation of steam pressure.

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7

Strengthen monitoring the operation of pulverizing system, care about coal

6.3.5Adjustment of steam pressure and evaporation

s oppage, c og o coa an pu ver ze coa as we as o er cases, rea n goo mefor any abnormality.

8When the load changes, activation or deactivation of the pulverized coal feeder,HT b ass switch coal ualit sudden chan e auto control device failureblowdown, soot blowing, slaging beating, superheater drain and emergency drain

switch is easy to bring about the changes of main steam pressure, so it shall beadjusted in good time. ,pressure operation mode under high load (the mode keeping stable superheatedsteam pressure and controlling load of the unit by adjusting the opening of speed-regulating steam valve is called as constant pressure operation), and apply

.certain value, recover constant pressure operation, i.e. the composite mode:constant pressure operation-operation at sliding parameters- constant pressureoperation.

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1.When the boiler is running normally, closely monitor and ensure that the temperatures of

6.3.6 Control and adjustment of steam temperature:

,+545, the temperature difference of them does not exceed 30, tube walls of thesuperheater and the reheater are not over temperature.

2.The temperature of superheated steam is controlled via changing water spray of the primaryand secondar attem eratin water of the su erheater. The rimar s ra desu erheatinacts as a master controller and can ensure no over temperature of the tube wall of plate

superheater. the secondary spray desuperheating is put in when spray amount of the primarydesuperheater is limited or the primary desuperheating amplitude is not satisfying, so as toensure no over temperature of the tube wall of HT superheater.

3.The control of reheated steam temperature is mainly realized via changing the opening of fluegas damper, the reheated steam temperature is controlled through changing the amount offlue gas flowing along LT reheater side by adjusting the opening of damper. in emergency,the emergency spray desuperheater on the reheater inlet tube in the LT section can be

,properly increased under low load as an assistant method for adjusting the reheated steamtemperature.

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4.Try to put the steam temperature in auto control, and closely monitor the changes of steam


.mode fails and then it switches to the manual mode, especially the reheated steamtemperature shall have enough aiming off, the operation shall be stable, spray changes shallbe even, and it must ensure that the steam temperature after desuperheating is not lowerthan the saturated temperature +11 under the pressure at any time.

5.regulating steam temperature via the flue gas damper, operate the damper in order, so as that

the sum of opening of flue gas dampers on the superheater side and the reheater side isalways more than 100%.

6.When the reheated steam temperature is higher than the specified value, the systemautomatically opens the emergency spray valve.

7.Close the spray valve tightly when it is under low load, the turbine trips and MFT activiates.

8.Steam temperature shall be controlled strictly as specified and it shall be treated according toaccident treatment s ecifications if it is out of limit so as to ensure safet of the e ui ment.

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9.Strengthen steam temperature monitoring in the following cases:


9.1Combustion is instable or it goes out.9.2The pulverizing system is started or stopped.9.3The steam pressure changes greatly.. .9.5Air quantity and air distribution mode change.9.6Fineness or quality of pulverized coal changes.9.7It has severe slaging and soot deposit inside or is under soot blowing.9.8Feedwater pressure is instable or its temperature changes greatly (such as

start/stop HT heater).

9.9Water seal at the bottom is damaged or the furnace and gas pass is leaking inquantity.

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10. Adjustment when the temperature of superheated steam is too high:


. .10.2Properly reduce excess air ratio.10.3Strengthen soot blowing of the water wall.

removal and soot blowing, temporarily stop doing so.

10.5If steam temperature on one side or the wall temperature is rising abnormallybecause of excessive deviation of gas temperature, try to adjust it and eliminate

.

10.6Stop some burners or the pulverizing system if necessary to reduce furnaceheat release rate.

10.7

If the steam tem erature is risin abnormall because that the attem eratinwater pipe is clogged, firstly try to reduce steam temperature, and then backwashthe desuperheater.

10.8If the quantity of attemperating water is influenced by its pressure, properly70

.


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11. Adjustment when the temperature of superheated steam is too low:


. desuperheater for a short time, temporarily open the operation desk ofattemperating water for drainage if necessary.

11.2Properly increase excess air quantity.11.3Strengthen soot blowing of the superheater.11.4When the steam temperature drops to 480, immediately open LT superheaterdrain valve, care about the changes of salinity in boiler water and steam. lower the

.

11.5If the steam pressure is high while its temperature is low, open PCV valve forpressure relief and improve the steam quality when superheat degree of steam is


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z Superheater steam temperature is regulated by ,attemperator systems.attemperator system roughly regulates the temperature. attemperatorsystem finely regulates the temperature. attemperator system controls thesaturation temperature 28 , however it is a recommendable value).attemperator system controls the final temperature

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z


can turn up the opening of the damper to change the smoke flow which passthrough the reheater system side. So the reheater steam temperature is regulated.As the superheater steam temperature, we can also start the attemperators whichare installed on the reheater export pipes to regulate the temperature. In addition,

changing the furnace wind is one of the assistance means.

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The attemperator system includes the following parts: steam line, spray nozzle,

Venturi mixing, thermal sleeve.


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Recommend Temperature


The Recommended

Temperature Value And

After Spray Attemperation

Alarm Tem erature

ature

Tempe

75Boiler Drum Work Pressure or RH Intel Pressure


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Gas temperature damper

Reheater flue Su erheater flue

Partitionwallcentre

Frontsurround wallcentre

Rear surroundwall centre

damper gas sga

damper

Supporter

supporter

Ash hooperDrive device

Support centre400

76

Linkage


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gas temperature damperAdvantages of the gas temperature damper:

) conversely, reasonably coordinating with the load , so the range load of thecontrol is wide.

) The reheater system has no middle header and is simple. It reducesres s ance an mprove e recyc e e c ency.

) No effect on the combustion.

) Little effect on the smoke temperature at the exports of the economizer ( running reliable. operation simple.

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regulate steam temperature by damper

) heat transference patterns:

-z Reheater-convection as main transference

) Process of regulating steam temperature and superheater and reheater steam

) Load down reheater temperature down flow down through the

reheaterreheater temperature up.

) flow down through the superheater superheater temperature down

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Curve about gas temperature damper

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6.3.7 Water and steam quality

In order to reduce the salt which is in the steam, we must control the quality ofthe water supply and purify the steam to satisfy the steam requirements.

In order to monitor the ualit of the su l water boiler water and steamsamplings and valves are installed on the supply pipes, ranked pipes, drum,

steam pipes, superheater inlet header, reheater inlet and outlet header. Thesampling for steam also has sampling head.

,of feed waterand boiler water to meet the requirements, steam quality will bein full compliance with standards and do not need to conduct regular sewage.

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6.3.7 Water and steam

qualityIf the quality of the boiler water is over the requirement, regular sewage can beac e on e con on a pr mary s eam pressure s ess an . a. on orthe water level of the drum. The time lasts less than 30 seconds. In high load, avoidthe regular sewage. In the following situation the regular sewage should be

rohibited:

Boiler anomalies (except high level)

When sewage system is out of work

When the power plant load is increasing or decreasing

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6.3 normal o eration ad ustment

Steam Qualit Index durin O eration


quality

Content Unit Value

H+ at 25s/cm


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Feedwater Quality Standard during Operation


quality

PHat 25 9.0-9.5*

Solved Oxygenug/L 7

Feug/L 20

Cuu /L 5

Total Hardnessumol/L 0

HydrazineN2H4ug/L 1050

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.


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Content Unit

CL- mg/L 1

PhosphatePO4 mg/L 0.53

o a a mg

Hardness umol/L 0

.SiO2 ug/kg 0.25

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6.3.8 Boiler blowdown

chemist. Regular blowdown shall try to be carried out under low load.

(2) Before blowdown, completely check the system, confirm that the equipment is in

,

its blowdown. in addition, lighting on the site is sufficient, and only special wrench

can be used when closing valves by hand as required.

, . ,

water deposit generates or the treatment effect is not good, high salinity may cause

carryover, so the blowdown can be carried out in the lower part of water wall,

.

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(4) Operation methods for program-controlled blowdown in the lower part of


4.1 Sludge deposit in the lower part of water wall shall be discharged viaintermittent blowdown at 24h interval in general. Properly raise the water levelof steam drum then, fully open the intermittent blowdown main valve andpr mary ow own va ve n regu ar, s ow y open t e secon ary va ve. ow ownof a single circulation loop must not exceed 30s. close the secondary valve, and

then close the primary loop, close the intermittent blowdown main valve afterblowdown of each loop. blowdown of two loops at the same time is not allowed.

4.2 Closely observe the change of silicon content in water duringstartup/shutdown and normal operation of the boiler, increase the blowdowncapacity if it is out of standard, and load down till the water is qualified if

(5) Adjust the continuous blowdown capacity according to chemical requirementsfor continuous blowdown of the boiler in operation.

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6 ualit of steam and water of the boiler deteriorates or continuous blowdown


capacity is insufficient or the continuous blowdown flash tank is failed andisolated, open electric adjustment angle valve from the continuous blowdownflash tank to the intermittent blowdown flash tank to increase continuousblowdown ca acit and close the valve in ood time after troubleshootin orquality of steam and water is acceptable.

(7) In blowdown, check whether the piping system and valve are clogged or leakingor not. completely check whether each blowdown valve is closed tightly or not. , .

(8) Blowdown is forbidden in the following cases:

8.1When the boiler fails (except when the water level is high).

. .

8.3When the feed pump is enabled/disenabled or is switching for failure.

8.4When the unit loads on or down.

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6.3.9 boiler soot-blowing

zSootblowin s stem includes decom ression sto s soot blowin i elines theirfixtures, guidance devices, soot-blowers, etc. In the boiler furnace, the level flue, therear shaft, air pre-heater, etc. are installed with steam soot-blowers.

z The steam of the soot-blowing comes from shield superheater, the steam parameter . .z When the sootblowings are working, pay attention to changes of the primary steam

temperature and pressure, furnace pressure. Ensure the steady combustion.z If sootblowers do not romote a osition to the limit, the are rohibited for back

operation.

z when the boiler load keeps stable at 70%BMCR, the boiler heating surface shouldbe cleaned completely by sootblowing. Further cleaning during the normal

.to run the sootblowing system once 8 (eight) hours.

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7. combustion tuning

7.1 purpose

stable combustion of the boiler is the key task for safe and economical

operation of the unit. When it is burning normally, ignition distance of

fuel is proper and it burns stably in the boiler, the flame shall not directly

scour the water wall, and its fullness is good, thermal load of the furnace

shall be even, and temperature difference at the outlet of furnace and flue

gas on both sides of each sections of gas pass must not exceed the designva ue no excee ng n genera no spec e n es gn , so as oreduce heat loss due to incomplete combustion, improve operation

economical efficiency of the boiler and ensure no over-temperature of the

.

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7.2 Key factors influencing combustion conditions

:

ea ures an com us on c arac er s cs o coa :

2 Air quantity required for complete combustion of fuel.

3. Reasonably organize the operation mode of burner.

4 Air quantity proportioning of the whole combustion system.

5 Maintain proper high furnace temperature, proper temperature of therimar and secondar air.

6 Reasonably adjust the coal pulverizing system and keep qualified coal

fineness.

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.

7.3.1 combustion systerm summary introduce

a pu ver zer s app e n s pro ec , oge er w pr mary a rdirect firing system. This PC system has the character of simple structure,few equipments, low resistance of coal pipes, low electricity consumption,convenient maintenance, reliable operation etc. Under boiler rated load(BRL), it can maintain a lower air/coal ratio compared to medium speedpulverizer and can achieve higher PC consistency as well. The system is

equipped with six (6) ball pulverizers. And each pulverizer supplies PCfor four burners. Each boiler is equipped with twenty four (24)concentrated HALF-PAX burners, which are located on boiler front archand rear arch (twelve nos of burners are arranged on each arch).

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7 3 b ti S t i t d


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7.3 combustion Systerm introduce

7.3.2 Primary air & vent air pipe

the PC-air first o throu h the

eccentric reducer to be accelerated,

most coal particles travel along the

outer radius of the elbow due to

centrifugal force, 50% PA and 10%

15% PC is extracted after the PCconcentrated-device, and be

transferred down to the vent air nozzle

by the vent pipe to burn in the furnace.

the minimum PA flow velocity at coal

pipe should not be less than 18m/s.

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7 3 b ti S t i t d


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7.3.3 Primary air & vent air pipe

boiler rated load capability.

The concentrated HALF-PAX burner is

equipped with a cylindrical sliding damper has

two SA zones with adjustable vanes located in

each zone which can enhance the ignition. Twoportions of SA pass through inner air zone and

outer air zone separately, A small portion of the

SA is admitted through the inner air zone and

swirled to aid the ignition. The outer SA passes

roug e ou er a r zone o supp y e requ reair for complete combustion.

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7 3 b ti S t i t d


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7.3.4 Sliding Air damper and air

zone disk

Through control the openning of

Sliding air damper,we can get

different total air for different burner.

Throngh control the openning of

air zone disk,we can change theportion of inner SA and outter SA

The recommend position:

cylindrical damper opening:80%

air zone disk opening :50%

"Cooling" position when the burner is out of service25%

94

"Coal firing" position, which is the balanced position during operation50%"Light-off" position80%.

7 3 combustion Systerm introduce


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7.3.5 Inner air & outer air vane control

The vortex strength of the inner SA can

be changed by the opening of the

The maximum opening of the innerSA adjustable vane is 60, the

the maximum o enin of the outer SA

minimum is 20 opening of the

inner SA adjustable vane is 45

adjustable vane is 80, the minimum

is 40, opening of the outer SA

Pulling the sliding ring outward closes the

95

vanes, and pushing the sliding ring inward

opens the vanes.


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. .

96

7 3 combustion Systerm introduce


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7.3.7 Windbox and Secondary Air Control

Open windbox is adopted in this boiler, which are located above and below

ron arc an rear arc . urner secon ary a r en ers e upper w n ox, anstaging air enters the lower windbox. The open windbox is designed to be ableto adjust the air distribution for combustion optimization, and makes theburning secondary air matching with coal flow from thePC exhauster , the airflow amount of burner secondary air and staging air can be adjusted by thewindbox inlet damper. To measure accurate flow amount, measuring device is

needed to mount at the upstream of each damper. Burner secondary airdamper and staging air damper can regulate the air amount as well as thestaging air .

One boiler is equipped with twenty four Vent Air nozzles, with eightnozzles on front wall, 12 nozzles on rear wall, they are located below

burners, and with 525mm horizontal offset to burners. The Vent Air pipe is equipped with pneumatic isolation valve, When some

burner needs to be out of service, close the pneumatic isolation valves,

97

valve.

7 3 7 Windbox and Secondary Air Control


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7.3.7 Windbox and Secondary Air Control

There are sta in air i es below each burner ever sta in air i e isequipped with electricdamper, which is split to two nozzles, each boiler hasfourty eight (48) such nozzles, with twenty four (24) on front wall, twentyfour (24) on rear wall. Staging air is extracted from bottom of windbox, anddamper has service position and cooling position, generally, it is onservice position when the corresponding burner is in service, and it is oncooling position when the corresponding burner is out of service. the flame

In virtue of the high designed velocity of staging air and reasonable angleenters furnace can benefits left up flame and control the flame shape, thestaging air chiefly functions at the addition air for complete combustion and

.

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7.3.8 Burner desi n fi ure desi n coal RO Boiler Rated ConditionITEMITEM UNITUNIT VALUEVALUE

Primar air tem eraturePrimar air tem erature 130130

Second air temperatureSecond air temperature 349.5349.5

Air temperature enter millAir temperature enter mill 280280

Pr mary a r ve oc ty at nozz ePr mary a r ve oc ty at nozz e m sm s 19.519.5

Second air velocity (inner zone)Second air velocity (inner zone) m/sm/s 19.619.6

Second air velocity (outer zone)Second air velocity (outer zone) m/sm/s 38.538.5

Vent air velocityVent air velocity m/sm/s 22.222.2

Staging air velocityStaging air velocity m/sm/s 47.4547.45

r mary a r ra o a nozz er mary a r ra o a nozz e ..

Secondary air ratioSecondary air ratio %% 54.954.9

Vent air ratioVent air ratio %% 9.79.7

99

Staging air ratioStaging air ratio %% 24.1924.19

Coal fineness RCoal fineness R9090 %% 44

7 4 Combustion tuning


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7.4 Combustion tuning

1.Try to put into related auto burning device in CCS, such as induced draft fan, forceddraft fan, primary air, secondary fan and fuel control devices are put into autooperation. in addition, strengthen the monitor of combustion, switch into manualcontrol in good time if the auto mode fails, and contact thermal personnel forrea men .

2. In normal operation of the boiler, load-on and load-down rate of the unit shall beadjusted according to load change rate specified. pay attention to keeping normalme um temperature n t e process. en oa ng on, rst y ncrease t e a rquantity, and then the fuel amount. whereas, firstly reduce fuel amount and then

the air quantity.

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7 4 Combustion tuning


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3. Observe the flame profile in the boiler when it is running. the flame shall bebright golden yellow, and evenly fill in the furnace if it is normal. Maintain

,sides are close to each other, temperature of flue gas on both sides of theheating surface of each section is also close. Adjusting secondary air damper,off-gas damper of burner and regulating lever/blade in the wind box can

,of the burner can change the shape of coal flow at the outlet of nozzles. when

the regulating lever/blade retracts, the coal flow diffuses. when the regulatinglever/blade extends, the coal flow contracts. Together with other dampers, itcan a us e pos on o ame n e urnace an ame pro e o avounfavorable flame scouring. The ignition point close to furnace arch cannotbe too high to avoid damage to burner nozzles because of overheating. Flameshall penetrate through the lower part of the furnace, and then turn upwards

rom e cen er. requen y c ec e opera on o eac urner n opera onto ensure its stable ignition.

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4. Adjust induced draft and forced draft quantity, maintain furnace pressurebetween -20-50Pa, furnace pressure alarm value at 980Pa, furnace

.quantity to ensure 1.5kPa wind box/furnace pressure as required,increase fuel amount and air quantity according to the load.

5. Oxygen content in flue gas shall be kept within 36%, so as to avoidslaging, incomplete combustion and secondary burning of rear gaspass

arising from oxygen deficiency, as well as avoid instable burning, exhaustloss and ower consum tion increase of fan because of excessive ox encontent. The changes of air quantity and oxygen content in flue gas shallbe closed monitored in operation, air quantity must not be less than 25%at any time.

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6. Regularly check the combustion of boiler, adjust and maintain properair/coal ratio to reach good burning condition. An ideal operation

con t on s t at t e num er o urners put nto operat on sat s es oarequirement of the boiler. When it loads down to lower than the minimumstable output of burner, stop some burners and pulverized coal feeders,

thermal load on furnace section shall be kept even when stopping burners.

fuel, it is preferable to put into some or all ignition oil guns of the coalburner.

8. Coal fineness shall be satisfying, convey speed in pulverized coal pipe mustbe more than 18m/s.

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9. When the quality of coal becomes bad, properly adjust the off-gas damper,reduce the speed at the outlet of coal nozzle, improve the coal

. ,adjust the anti-vortex blade and increase the intensity of vortex at theoutlet of the primary air coal nozzle, which are helpful for coal ignitionand stable combustion. Feed oil in good time to support combustion and

.

10. In normal operation of the boiler, frequently check air leak of the properand as ass check the ti htness of each art. each valve and hole shall beclosed tightly, and the bottom ash hopper shall be sealed well.

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recommended solution

TROUBLE PROBABLE CAUSE CORRECTION

1Abnormali ty of lighter f lame.2Lean coal-air mixture to burner. 1To adjust the flame conf iguration orposition.

Ignition difficulty3Inadequate burner swirl or high

transition zone air f low

4Low temperature of PA and SA.2.To increase coal-air ratio

3 Check/reset inner/outer vane and /or innertransition zone damper setting.

4To increase the temperature of SA and PA.Flame failure

after startupIgniters removed too early

Leave igniters in service until furnace and

secondary air temperature are sufficient

based on experience

Flame failure

during the

normal

e o er opera ng oa sbelow design minimum firing

rate.

2 Interrupted PC feeding to1To increase the PC flow for higher burner

heat input.

2Check PC feeders and PC supply.3NO soot blowin to the burner area when the

105

opera on urner.

3Flame failed by soot blowing

boiler load is lower than 50% BRL.


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recommended solution

Uneven Flame Poor secondary air dist ribution To check air damper and vanes,

-

burner thtoat

throatIncrease opening of outer spin vane.

Sparklers in thePulverized coal to coarse To adjust the pulverizer classif ier

Ignition far away

from the

burner nozzle

Higher SA or PA velocity

To reduce the opening of inner/outer

vanes, and re-calibrate the PA flow

rate

Furnace pressure

1Poor PC feeding2Unstable igni tion at nozzle3 Poor furnace draft control

1Refers to the PC Feeder Manual2Check primary air flow and pc

temperature.

106

3To increase the induced draft offurnace

7.6 Oxygen control


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The Curve About Economizer Outlet Oxygen Content And Boiler

Load (Design Coal)

107

8 Troubleshooting


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Troubleshooting principle

When accident happening, the captain should be under the unified leadership in

u y- ea er naccor ance w e prov s ons o s regu a on, promp y a eall possible measures to lift the accident on the threat to the security of persons

and equipment, correct handling of accidents to prevent the accident further.

Uuder ensuring the premise of personal and equipment safety, should make

every effort toquickly restorehe normal run quickly, with meeting the

system load requires.

After treated a accident, operating personnel should faithfully record the time of

the accident happened, the phenomenon and the measures taken. And keep the

printing records, recording curves etc. in a saft place for the accident analysis

If the accident occurred at shift changes, the treatment should be completed bycurrent shift, then proceeding shift change.

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8.1 lost flame


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1.Phenomena:

MFT action, primary fan as well as the following auxiliary euipment tripped, thepower of the powder feeder and powder feeder tripped, oil tripped valve and oilangle valve closed, and accompanied with sound and light alarms.

.

Dark in boiler, can not see flames from the watching fire hole, fire inspection lights all

out, no flame display on CRT screen.Drum water level increased after the instantaneous drop, steam temperature, steampressure drop.

As a result of burst pipes caused by fire, the watching fire hole and the other partcould has emitted flue gas and steam, the water level continued to decline

.

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8.1 lost flame


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2.Reasons:The negative pressure in furance pressure is too high.

The automatic process procedure unnormal when occurs the process exception RB.

oa a y or coa n mu a ons, com us on e er ora on.The heated surface in furance serious blow off.

Long-term low load running, the furance temperature low caused due to the surplus airvolume overlage

When Low-load operating, the adjustment operation improper, oil is not stable combustion.

Fuel oil System Failure, such as poor fuel atomization, oil mixed with water, fuel pressure loss,

etc..Boiler soot blowin sla removal o eration without rior contact or im ro er o eration.

Bottom seal has been damaged to a lot of moisture or cold air leakage into the furance.

The primary and secondary air imbalance.

Fineness of PCis too thick.

om us on con ro a ure or pro ec on ev ce ma unc on.

When the load lower, gas shutter opening is too large.

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8.1 lost flame


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3 Treatment:Sure to check MFT action when fire have been extingished, or immediate

manual MFT immediate, strictly prohibited to restore burning usingKnock method.

All the unit control wa shoula be switched to manual for the boiler. re ort

duty leader to call for reducting unit load rapidly.

Manually maintain the normal level in the drum, confirme the warm waterwithdrawn.

After extingished causes identified, try to remove and make purging. MFT

reversion, then re-igniting in according with the requirement of the hot

state to restore the normal o eration.

If the fire of unknown cause or a short period of time is difficult to remove,

regard as hot standby shutdown for processing.

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8.2 drum excess water


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1.Phenomena:

The water level hi h alarm si nal, indicatiin at hi h water level of the water.

Water flow unnormally greater than the steam flow.

When full water Seriously, the main steam temperature decline sharply in themain steam tem erature, occurrin water im act in main steampipe ,flange joints to take out white steam.

When water level protection put into, the emergency drainage gates openautomatically.

When the water level high to three values, MFT action.

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8.2 drum excess water


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2.Reasons:

-, , ,

seat gate opened, so that the pressure drop of drum too fast, resulting in

rapid vaporization of boiler water to form a false water level.

abnormal to make water flow is much greater than the steam flow.

Working conditions change too much, do not adjust in time.

auge n ca on s no correc , so a opera ng personne ncorrec u ge.

Lax monitoring of the water level, adjust the improper or misoperation.

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8.2 drum excess water.


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If the water level instruction is incorrect, contact maintenance or thermal personnel forhandling rapidly.

If inade uate surveillance when drum water level more than three values but the MFT

is not action, should contrasting with the water level gauge, after identified as full ofwater, immediately MFT manually for handling. After manual MFT , the waterlevel control change to manual immediately, to reduce water volume. At the

identifiing as drum excess water .

Where is the water supply pump governor failure, manual can not reduce waterflowrate, should stop the fault pumps and start standby pump with linkage or

.

If the water level continues to rise to three values, MFT should be action, or elsemanually MFT.

After MFT check reducted warm waterthat has been automaticall closed or or else

manually shut down, at the same time open the superheateroutlet steam trap.Identify and eliminate causes of failures. After the drum water level up to normal

water level, ready for re-igniting.

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causes o rum excess wa er un nown or can no e e m na e , e regar as ostandby shutdown for processing.

8.3 Lack of water


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1.Phenomena:

,

lower level.

Water flow is less than the steam flow (in the case of water levels caused by

,

opposite).

When a serious water shortage, the overheated steam temperature rise,- .

The water level as low as three values, MFT action.

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8.3 Lack of water


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2.Reason:Feed water automatically failure.

Feed water motor-operated valve errors.Feed water pressure low, feed water flow rate inadequate or water system

severe leakage caused by water supply pump or water supply system.

A serious leak of sewage gate strictly.

Accident release valve misopen or serious leak.-

off.

Water cooling wall, economizer piping severe leakage.

Unit load reduced sharply to result in vapor pressure escalating sharply,resu t ng n s ort-term ow- eve a se.

Water level indication is not correct, so that operating personnel having aincorrect diagnosis.

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, , .

8.3 Lack of water.


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If the water level instruction is incorrect, contact maintenance or thermalpersonnel for handling rapidly

After Proofreadin the water level au e and confirmin the water level lower

the water level control immediately is chang to manual , increasing thewater volume.

Where is the water supply pump governor failure, manual can not increase, , ,

and stop failed pump as necessary.

Less combustion, appropriate to reduce the load, but load can not reduce toofast to avoid pressure increases, causing a false low level, resulting in MFT.

Immediate stop the periodic discharge and continuous discharge.

Check water supply, sewage systems and the emergency drain valve position iscorrect, whether the leak.

wa er au oma c a ure cause y ow uc ua on o empera ure re ucewater, should be out of temperature reduced water and feedwaterautomatically , by mannul to maintain drum level.

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8.3 Lack of water


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If the drum water level continues to drop to three values, MFT should be action,else or manuall MFT.

After MFT, may continue to increase to the amount of water until the waterlevel back to normal, water shortage to be identified and eliminated, canready for re-igniting.

causes o wa er s or age un nown or can no e e m na e , e regar ashot standby shutdown for processing.

If operating staff negligence, not found in the process of water level reducting,the water level have reached the three values when found, should make anemergency shutdown. Not allow to the unauthorized water after shutdown .it be regard as hot standby shutdown for processing.. And reporting to dutyleader. re-water supply and starting boiler is decied by the Chief Engineer.

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8.4 water wall priming


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1.Phenomena:

. ,

can not see the water level.

Main steam temperature is dropped rapidly

er ous y, s eam p pe, wa er ammer occurs n s eam p pe, ange run ou s eam.

Salinity in saturated steam and boiler water increases.

2.Reason:

Boiler water quality is poor, excessive suspended solids, or salt, containing oil.

Failing to excessive sewage or chemical dosing too much.

oa surge, s eam pressure roppe s gn can y.

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8.4 water wall priming


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3.Treatment:

A ro riate to reduce the boiler load, and maintain stabilit .

Turn the automatic feedewater to manual, appropriate to reduce the water level,while strengthening to wash control for the water level meter .

Full o en with row of ates and door accident draina e ate, and enhance tofeedwater, to improve the boiler water quality and to preventwater level toolow.

Control of steam temperature will be changed from automatic to manual.reduce the volume of temperature reducture water until the splittingdesuperheater. Try to maintain steam temperature normal.

Stop dose into boiler, and strengthen the boiler water sampling and analysis,.

Before the boiler water quality improving, not allowed to increase the load.

Fault elimination should be back to normal o eration.

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8.5 Water wall damage


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1.Phenomena:

, , ,

boiler extinguished, MFT action , and having abnormal sound from

boiler. flue gas were emitted from the unsealing places of boiler.

, .

Wicket Fan abnormal, current increase.

.

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2.Reasons:Water supply, boiler water quality failure, improper boilerwater so that the

nner wa sca ng, corros on.Combustor, soot blower installed improperly, causing water wall tube is

worn, blowing loss.

,poor, materials failure, welding quality problem.

Combustion unreasonable, long-term low-load run, local severe slaging inboiler , steam pressure dropped drastically, the water level is too lowan regu ar sewage ea ng ou a o o excess ve e c. resu n poor wa ercirculation.

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The pipe was blocked by foreign objects when maintenace so that poor water

, .

Pipes were in high temperature zone,hapenning high temperature corrosion

or the uneven distribution of the heat load so that cause the pipe

- .

Boiler severe water shortage, suddenly a lot of water entering into.

A large slaging falled smash the ash bucket or water ccoling wall

Improper operation, so that uneven heated or boiler running with super-

pressure .

Happening explosion in boiler, damage to water wall tube.

Neighboring pressure pipe leakage, damage to water wall tube.

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3 Treatment


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3.TreatmentReporting to duty leader,the operation mode will be turn to the boiler manual

mode.When leaka e is not serious manuall increased the water su l flowrate

to maintain the normal water level. Simultaneously, less burning. As necessary,puting into fuel oil to stabilize burning. And reducing load to maintain run inshort time, then shutdown.

, ,Make preparations and take safety measures to prevent the accident furtherenlarge.

If a serious leak, unable to maintain normal operation, should press MFT in hand toemergency shutdown. Keep a inducted draft fan operation, maintain thenegative pressure infurance.stop the run after exhausting steam within the boiler.

After boiler shutdown, should be shut down the recirculation valve on coaleconomizer when water enterin . As far as ossible maintain water level.Should

can not maintain the water level, should stop water entering.Other operations after boiler shutdown are same as the normal shutdown operations.

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8.6 Economizer tube damage


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1.Phenomena:

,

decline in severe or even difficult to maintain.

The negative pressure in furance and the stack is smaller or positive pressure.

e n uce s a an gu e vane open ng arge, a curren ncrease.

Economizer has abnormalsound nearby, spray steam outside at the unsealing

locations.

Temperature difference increase on both sides of Economizer,the flue gas

temperature damaged side , exhaust gas temperature as well as primary

and secondary air temperature of the air pre-outlet ofthe side decreased.

Serious, economizer ash bucket overflow occurs.

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8.6 Economizer tube damage2.Reasons:


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Water quality failed so that pipe wall corrosion.

Water suplly flowrate, temperature changes too large and too frequent sothat metal fatigue damage.

Pipe material Unqualified, poor welding quality , poor installation and

maintenance techniques.

Fly ash abrasion or Economizer recombustion occured.

In startu and shutdown rocess not o en water recirculation valve when

stop water entering.

Neighboring pressure pipe leakage, loss of economizer tube blowing.

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8.6 Economizer tube damage3.Treatment:


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When Leakage is not serious, the water supply control mode turn from automaticto manual, then increasethe amount of the water , and stop all sewage and

drainage work to maintain the water level. Simultaneously, by reducing the unitload maintain short run, and apply for shutdown.

Strengthen to examine damaged parts, close attention to its developping closely, Make

If a serious leak, unable to maintain normal operation, should press MFT in hand toemergency shutdown. Keep a inducted draft fan operation, maintain the

negative pressure infurance.stop the run after exhausting steam within the stack.e rum eve ou e ma nta ne a ter t e s ut own . c ose a t e sewage , waterdischarge gates and economizer recirculation gata. If unable to maintain the waterlevel, should stop the water entering.

Contact Auxiliar e ui ment attendant sto ESP run.the ash within the economizer

air preheater and ESP hopper exhausted .Other operations after boiler shutdown are same as the normal shutdown operations.

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8.7 superheater tube damage

1 Ph


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1 Phenomena:Overheated steam pressure and flowrate decreased, water flow is abnormally

greater t an t e steam ow.The pressure in furance and the stack increased or positive pressure.When aserious explosion the upper furance superheater tube will cause acombustion instabilit and even extin uished. There is abnormal sound atthe locations defected and spray steam outside at the unsealing locations..

Drum water level rose instantaneous and then drop down.

Overheated steam temperature varies with the leakage area. And when highempera ure sec on amage , s eam empera ure ec ne. en ow

temperature section damaged, steam temperature rise.

The temperature difference at both sides behind superheaterincrease ,the gastem erature on one side dama ed decline .

The openning of g

3.boiler operation

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