BOILER

SABARI GIRISH N

SR. ENGINEER (O)

SESSION PLAN

Boiler fundamentals

Principle of Combustion

Classification of Boilers

Arrangement of main boiler

WHAT IS A BOILER?

“BOILER” means any closed vessel exceeding 22.75 litres in capacity which is used expressly for generating steam under pressure and includes any mounting or other fitting attached to such vessel, which is wholly or partly under pressure when steam is shut off. As per INDIAN BOILER REGULATIONS

COAL FLUE GAS

CO, CO2, H2, H2O, 02 AIR ASH

BOILER

STEAM

WATER

BOILER FUNDAMENTALS…

COMBUSTION EQUATIONS..

C +O2 CO2 33820 KJ/Kg

2C+O2 2CO 10200 KJ/Kg

2H+O2 H2O

S +02 SO2

COMBUSTION EQUATIONS..

AIR REQUIRED =4.31[(8/3)C – 8(H-0/8)-S]

ATMOSPHERIC AIR = N2 - 77% O2 - 23% by weight

N2 -79% O2- 21% by volume

EXCESS AIR FOR COMPLETE COMBUSTION- 15 TO 20%

REQUIREMENTS FOR GOOD COMBUSTION

3Ts temperature time Turbulance

COMBUSTION EFFICIENCYDesign of the boilerFuel usedSkill of obtaining combustion with minimum excess air ( CO monitoring)

EFFICIENCY CALCULATION METHODS

DIRECT METHOD IN-DIRECT METHOD

CLASSIFICATION OF BOILERS

BASED ON ARRANGEMENT

FIRE TUBE

WATER TUBE

CLASSIFICATION OF BOILERS

FIRING ARRANGEMENT FRONT FIRED CORNER /TANGENTIAL FIRED GRATE FIRED PULVERIZED FUEL FIRED

CIRCULATION NATURAL CIRCULATION FORCED CIRCULATION

CLASSIFICATION OF BOILERS

APPLICATION UTILITY BOILERS INDUSTRIAL BOILERS

CONSTRUCTION TOWER TYPE TWO PASS BOILERS

MANUFACTURERS CE-BHEL ANSOLDO LMZ

COMPONENTS OF A BOILER ECONOMISER BOILER DRUM DOWN COMERS WATER WALL PRIMERY SUPER HEATER PLATEN SUPER HEATER FINAL SUPER HEATER RE-HEATER BURNER OIL GUNS IGNITORS BUCK STAYS

STAGE-I

ECONOMISER

FORMS PART OF FEED WATER

CIRCUIT

PRE HEAT BOILER FEED WATER

RECOVERY OF HEAT FROM FLUE GAS

LOCATED IN BOTTOM OF REAR PASS

NO STEAM FORMATION

BOILER DRUM

TO SEPARATE WATER FROM STEAM

TO REMOVE DISSOLVED SOLIDS

TO PROTECT WATER WALLS FROM

STARVATION

ACTS AS TEMPORARY PRESSURE RESERVOIR

DURING TRANSIENT LOADS

WATER WALL

FORMS FURNACE ENCLOSURE

GENERATION OF STEAM

PROVIDES SEALING TO FURNACE

SUPER HEATER

RAISE STEAM TO HIGHER TEMPERATURE

ARRANGED IN 3 STAGES

LTSH LOCATED ABOVE ECONOMISER

RADIANT PENDENT TYPE (DIV PANEL)

ABOVE FURNACE

CONVECTIVE FINAL SUPER HEATER

ABOVE FURNACE IN CONVECTIVE PATH

RE HEATER RE HEAT THE STEAM FROM HP TURBINE TO 540 DEG

COMPOSED OF THREE SECTIONS

RADIANT WALL REHEATER ARRANGED IN FRONT &

SIDE WATER WALLS

REAR PENDANT SECTION ARRANGED ABOVE GOOSE

NECK

FRONT SECTION ARRANGED BETWEEN UPPER HEATER

PLATEN & REAR WATER WALL HANGER TUBES

BURNERS

32 COAL BURNERS & 16 OIL BURNERS IN ALL

IN CE TYPE BOILERS OF STAGE-II 500 MW

24 COAL BURNERS & 24 OIL GUNS IN STAGE-I

ANSALDO BOILER ARRANGED ON THE FRONT

IN 500 MW BOILERS BURNERS CAN TILTED +30

TO -30. DENPENDING ON THE REQUIREMENT

NO SUCH PROVISION IN STAGE- 1 BURNERS

IGNITORS

EACH GUN IS PROVIDED WITH AN IGNITOR

HIGH ENERGY ARC, EDDY CURRENT IGNITORS

OUT PUT VOLTAGE 2500V DC

SPARKS 4 SPARKS PER SECOND

DUTY CYCLE 15 MIN ON , 30 MIN OFF

CONTROL CIRCULATION PUMPS

THREE PUMPS PER BOILER(2X50%)

ASSIST IN CIRCULATING WATER THROGH

WATER WALL TUBES

EACH PUMP CAPACTY 2879.4 T/HR

DIFFERENTIAL PRESSURE 1.948 KSC

SPECIFIC GRAVITY .5993@362

DEG

BUCKSTAYS

MECHANICAL SUPPORT BEAMS

SUPPORTS BOILER ENCLOSURE

TO SAFE GUARD FURNACE

GEOMETRY , EXPECIALLY FURNACE

EXPLOSION /IMPLOSIONS

BOILER AUXILIARIES COAL FEEDERS MILLS PRIMARY AIR FANS SEAL AIR FAN FORCED DRAFT FANS WIND BOX SCANNER FAN AIR PRE HEATERS ESP INDUCED DRAFT FANS CHIMNEY SOOT BLOWERS

COMBUSTION

Constituents of coal (%) Carbon 36.54 Volatile matter

21.6 Moisture 10 Ash 32 Sulphure .38

500 MW RSTPS BOILER

MANUFACTURER BHEL-(CE DESIGN)

TYPE BALANCED DRAFT, DRY BOTTOM, SINGLE DRUM, CONTROLLED CIRCULATION PLUS, TILTING TANGENTIAL

NO OF MILL WITH OUT OIL SUPPORT

2 ADJACENT MILLS @ 50% OF CAPACITY

EXPLOSION/IMPLOSION CAPACITY

+660 OR -660 mmwc

VOLUME 14820 M3

SIZE 62.456MTR (FROM BA HOPPER TO FURNACE ROOF) X 15.289 X 18.034

TUBES OD -51MM THICKNESS-5.6MM, PITCH 63.5 DSGN PR 208.8 SA 210CWT 583.2 TONS

DRUM 22070X2130X1778 END THICKNESS 152.4mm CYCLONES 96 SA 299 WT 246 T, ( 224 T WITHOUT INTRNL)

CAPACITY 10 SEC FROM NORMAL TO LO-LO TRIP

SAFTEY VALVES DRUM -6 SUP HEATER 6 (2+4), CRH -4, HRH -8 (4+4)

TUBE LENGTH 350 KM approx( FOR 500 MW BOILER) , 58000 BUTT WELLDS approx

PARAMETERS

Flow MCR NCR

S H steam 1725 1384

RH steam 1537 1527

Feed water 1725 1527.3

Spray 22.7

Secondary 1464 1337

Primary air 558 477

Total Air 2021 1814

COAL( 4300 kcal/kg)

296 266

COMPARISONSL. NO

PARAMETER ST.-1 ST.-2

1 FIRING FRONT FIRED CORNER FIRED

2 CIRCULATION NATURAL CONTROLLED

3PF

TRANSPORTATIONPA FAN TO EACH MILL

COMMON PA FANS-2NOs.

4 OIL LFO/HFO LSHS or HFO

5 REHEATERS IN CONVECTIVE ZONEIN CONV. &

RADIATION ZONE

6 APHsCOMMON TO SEC. AND

PRIMARY AIRSEPARATE APHs

7 FLY ASHING CONTINUOUS(u#2 & 3) INTERMITTENT

8 BOILER CONTROL BMS FSSS

9 COAL MILL BALL AND RACE BOWL

Contd.SL. NO

PARAMETER ST.-1 ST.-2

10SH/RH TEMP.

CONTROLGAS BY PASS &

ATTEMPERATIONATTEMPERATION &

BURNER TILT

11 DOWN COMERS 7 6

12SECONDARY AIR

CONTROLNOT POSSIBLE POSSIBLE

13MILL CHANGE

OVERREQUIRE GUNS’

SUPPORT

ADJACENT MILL SUPPORT IS SUFFICIENT

14 IGNITORSREQUIRES LFO

SUPPORTHIGH ENERGY ARC.

NO OIL.

15 OIL GUN TIP Y J

16 AIRPRIMARY AIR,

SECONDARY AIRPA, SA, AUX. AIR, END

AIR, OVER FIRE

Contd.

SL. NO

PARAMETER ST.-1 ST.-2

17 FD FAN CONTROLVANE

CONTROLBLADE PITCH

CONTROL

18 PA FAN CONTROLVANE

CONTROLBLADE PITCH

CONTROL

SAFETY VALVES ( STAGE-II) BOILER DRUM 6 SPRING LOADED SUPER HEATER 2 SPRING LOADED, 4 ERVs CRH 4 SPRING LOADED HRH 4 SPRING LOADED, 4 ERVs

NO SET PR RESET PR %BLOWDOWN

B1 200 191 4

B2-B6 202- 206 192-196 5

SH 184 178 3

SH ERVs 180-182 176-178 4.8

CRH 55-56 53-55 3

HRH 48.5-49 47-47.5 3

HRH ERVs 47.5-48 46.6-47 1.97

SOOT BLOWING SYSTEM NO BLOWERS 104+34+4

WALL BLOWER LRSB TRAVEL 305 9200 mm NOZZLE DIA 26 32 mm BLOWING PRESSURE 12 12.5 ksc TIME 1.44 MIN (PER PAIR) RATE 833 KG/HR (PER PAIR) 293 CONSUMPTION 116.62 KG (PER PAIR)

3349 (PER GROUP)

ELECTRO STATIC PRECIPITATOR COLLECTION EFFICIENCY 99.9% TREATMENT TIME 33.33 SEC DUST CONCENTRATION 115mg / M3 (LIMIT) COLLECTING RAPPER FREQUECY 15- 2 RAPS/ HR EMITTING RAPPER FREQUECY 10 RAPS /HR HOPPERS 96 HOPPER CAPACITY 8HRS +10% HOPPER HEATERS 96X6 FIELD CURRENTS ( mA) 150 250 325 450 600 750 VOLTAGE 70 KV PEAK